Clinical Features and Outcomes of Immune Checkpoint Inhibitor–Associated AKI: a Multicenter Study

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Clinical Features and Outcomes of Immune Checkpoint Inhibitor–Associated AKI: A Multicenter Study

Frank B. Cortazar,1,2 Zoe A. Kibbelaar,3 Ilya G. Glezerman ,4 Ala Abudayyeh,5 Omar Mamlouk,5 Shveta S. Motwani,3,6 Naoka Murakami ,3 Sandra M. Herrmann,7 Sandhya Manohar ,7 Anushree C. Shirali,8 Abhijat Kitchlu,9 Shayan Shirazian,10 Amer Assal ,11 Anitha Vijayan,12 Amanda DeMauro Renaghan,13 David I. Ortiz-Melo,14 Sunil Rangarajan,15 A. Bilal Malik,16 Jonathan J. Hogan,17 Alex R. Dinh,17 Daniel Sanghoon Shin,18,19 Kristen A. Marrone,20 Zain Mithani,21 Douglas B. Johnson,22 Afrooz Hosseini,3 Deekchha Uprety,3 Shreyak Sharma ,3 Shruti Gupta ,3 Kerry L. Reynolds,23 Meghan E. Sise,1 and David E. Leaf 3

Due to the number of contributing authors, the afﬁliations are listed at the end of this article.

ABSTRACT Background Despite increasing recognition of the importance of immune checkpoint inhibitor–associated AKI, data on this complication of immunotherapy are sparse. Methods We conducted a multicenter study of 138 patients with immune checkpoint inhibitor–associated AKI, defined as a $2-fold increase in serum creatinine or new dialysis requirement directly attributed to an immune checkpoint inhibitor. We also collected data on 276 control patients who received these drugs but didnotdevelopAKI. Results Lower baseline eGFR, proton pump inhibitor use, and combination immune checkpoint inhibitor therapy were each independently associated with an increased risk of immune checkpoint inhibitor– associated AKI. Median (interquartile range) time from immune checkpoint inhibitor initiation to AKI was 14 (6–37) weeks. Most patients had subnephrotic proteinuria, and approximately half had pyuria. Extrarenal immune-related adverse events occurred in 43% of patients; 69% were concurrently receiving a potential tubulointerstitial nephritis–causing medication. Tubulointerstitial nephritis was the dominant lesion in 93% of the 60 patients biopsied. Most patients (86%) were treated with steroids. Complete, partial, or no kidney recovery occurred in 40%, 45%, and 15% of patients, respectively. Con- comitant extrarenal immune-related adverse events were associated with worse renal prognosis, whereas concomitant tubulointerstitial nephritis–causing medications and treatment with steroids were each associated with improved renal prognosis. Failure to achieve kidney recovery after immune checkpoint inhibitor–associated AKI was independently associated with higher mortality. Immune checkpoint inhibitor rechallenge occurred in 22% of patients, of whom 23% developed recurrent associated AKI. Conclusions This multicenter study identifies insights into the risk factors, clinical features, histopathologic findings, and renal and overall outcomes in patients with immune checkpoint inhibitor–associated AKI.

JASN 31: ccc–ccc, 2020. doi: https://doi.org/10.1681/ASN.2019070676

Received July 9, 2019. Accepted November 21, 2019. Immune checkpoint inhibitors (ICPis) are a novel class of immunotherapy that have revolutionized F.B.C. and Z.A.K. contributed equally to this work. 1,2 the treatment of a number of malignancies. Published online ahead of print. Publication date available at By targeting inhibitory receptors expressed on www.jasn.org. T lymphocytes, other immune cells, and tumor Correspondence: Dr. Frank B. Cortazar, New York Nephrology cells, these monoclonal antibodies enhance tumor- Vasculitis and Glomerular Center, 62 Hackett Boulevard, Albany, directed immune responses, and have been dem- NY 12209. Email: [email protected] onstrated to be highly effective in treating a broad Copyright © 2020 by the American Society of Nephrology

JASN 31: ccc–ccc,2020 ISSN : 1046-6673/3102-ccc 1 CLINICAL RESEARCH www.jasn.org spectrum of malignancies.3 However, the increased antitumor Signiﬁcance Statement activity achieved with these agents comes at the cost of a unique spectrum of autoimmune phenomena known as immune- Kidney toxicity from use of immune checkpoint inhibitors is being related adverse events (irAEs).4 The incidence of irAEs in recognized as an increasingly frequent complication of treatment. – patients receiving ICPis ranges from 60% to 85%, with the However, existing data on immune checkpoint inhibitor associated AKI have been limited to small, mostly single-center studies. In this skin, gastrointestinal tract, and liver being the most common multicenter study of 138 patients with immune checkpoint in- organs affected.1,5 Renal complications of ICPis, although less hibitor–associated AKI and 276 controls, the authors characterize common, are becoming increasingly recognized as the use of the clinical features of this complication and identify risk factors these agents continues to expand.6 associated with its development, clinicopathologic features, and The estimated incidence of immune checkpoint inhibitor– determinants of kidney recovery after an episode. Failure to achieve kidney recovery was associated with worse overall survival, and a 7 associated AKI (ICPi-AKI) ranges from 1.4% to 4.9%. Initial minority (23%) of patients who were retreated with immune reports described tubulointerstitial nephritis (TIN) as the checkpoint inhibitors had a recurrence of AKI. The study provides most common renal lesion caused by ICPis,7,8 although other insights into immune checkpoint inhibitor–associated AKI, although immune-mediated pathologies have also been reported, further study is needed to inform the care of affected patients. including various glomerulonephritides.9 Despite increasing recognition of the importance of patient characteristics as potential risk factors for ICPi-AKI. ICPi-AKI, our current understanding of ICPi-AKI is limited The temporal distribution of ICPi initiation was similar be- to case reports and small case series, the largest of which in- tween cases and controls (Supplemental Table 2). cluded 16 patients.9 We therefore conducted a multicenter, retrospective study comprising 138 patients with ICPi-AKI to Data Collection determine the independent risk factors for development of We collected detailed clinical data on all patients using a secure, ICPi-AKI, the clinical and pathologic features associated with standardized, electronic case report form (REDCap). Data col- ICPi-AKI, the key factors associated with kidney recovery after lected from each patient included demographics, comorbidi- an episode of ICPi-AKI, the risk of recurrent AKI with ICPi ties, use of concomitant potential TIN-causing medications, rechallenge, and the effect of ICPi-AKI on overall survival. longitudinal SCr and other laboratory values, kidney biopsy data, treatment data, data on ICPi rechallenge, and data on renal and overall outcomes. Additional details on clinical data METHODS collected are in the Supplemental Appendix 1.

Overview Definitions of AKI Severity, Kidney Recovery, and We performed a multicenter, retrospective cohort study to assess Recurrent ICPi-AKI the clinical features and outcomes of ICPi-AKI. We contacted AKI severity was staged according to the Kidney Disease Im- nephrologists and oncologists at 26 major academic cancer proving Global Outcomes criteria.10 By definition, all cases centers across the United States and Canada to identify cases were stage 2 (doubling of SCr) or stage 3 (tripling of SCr or of ICPi-AKI. All protocols were approved by the Massachusetts need for RRT). We defined complete recovery of AKI as a re- General Hospital institutional review board, and by the insti- turn of SCr to ,0.35 mg/dl above the baseline value, whereas tutional review boards of all participating sites. we defined partial recovery as a return of SCr to .0.35 mg/dl but less than twice the baseline value, or liberation from RRT regard- Patients with ICPi-AKI less of the SCr value.7,11 Recurrent ICPi-AKI was defined as a Patients with ICPi-AKI were included if the AKI was attributed doubling of SCr or need for RRT after rechallenge with an ICPi. directly to the ICPi by the treating provider and the patient had at least a doubling of serum creatinine (SCr) or the require- Statistical Analyses ment for RRT. In total, 18 institutions (Supplemental Table 1) We performed the statistical analyses with Stata version 14 contributed 138 cases that met the above criteria for ICPi-AKI. (StataCorp., College Station, TX). Continuous and categorical data were compared using the Wilcoxon rank-sum and Fisher Control Patients exact tests, respectively. Univariate and multivariable logistic To identify risk factors for development of ICPi-AKI, we also regression were used to identify risk factors for incident collected data from 276 patients from contemporaneous ICPi-AKI, and, among those with ICPi-AKI, to identify factors registries at Dana Farber Cancer Institute (n=107) and associated with kidney recovery. We used the Kaplan–Meier Massachusetts General Hospital (n=169) who received ICPis method to estimate the cumulative death rate over time, and but did not develop AKI (case-to-control ratio of 1:2). All pa- Cox proportional hazards models to identify risk factors tients treated with ICPis were eligible to serve as controls except associated with increased mortality. Selection of covariates those who sustained an episode of AKI (defined as .50% in multivariable models was based on univariate associations increase in SCr). Random, rather than matched, selection of and biologic relevance. We used Schoenfeld residuals and controls was chosen to preserve the ability to investigate all ln-ln plots to verify that the proportional hazards assumption

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Table 1. Baseline characteristics for ICPi-AKI prior autoimmune disease (Table 2). The Variable ICPi-AKI (n=138) Controls (n=276) P Value magnitude of association was greatest for Age at ICPi initiation, yr 67 (58–74) 65 (56–73) 0.36 ICPi combination therapy (adjusted odds fi Female, n (%) 55 (40) 105 (38) 0.75 ratio, 3.88; 95% con dence interval, 2.21 Race, n (%) 0.15 to 6.81). White 116 (84) 248 (91) Among cases, baseline characteristics Black 10 (7) 10 (4) were similar in biopsied and nonbiopsied Asian 3 (2) 5 (2) patients (Supplemental Table 3). Likewise, Comorbidities, n (%) thesameriskfactorsforICPi-AKIwere Hypertension 77 (56) 171 (62) 0.24 identified in the subset of patients who un- Diabetes 23 (17) 47 (17) 1.00 derwent renal biopsy (Supplemental Table 4). CHF 3 (2) 11 (4) 0.40 COPD 6 (4) 36 (13) 0.005 Clinical Features of ICPi-AKI Cirrhosis 2 (1) 15 (5) 0.06 Baseline SCr, mg/dl 0.91 (0.80–1.21) 0.87 (0.70–1.06) 0.002 AKI developed at a median of 14 (interquartile – Baseline eGFR, ml/min 72 (55–89) 83 (63–99) ,0.001 range [IQR], 6 37) weeks after ICPi initiation CKD, n (%) 44 (32) 56 (20) 0.01 (Figure 1A), and 2 (IQR, 2–3) weeks after the CKD IV, n (%) 9 (7) 2 (1) 0.001 last ICPi dose (Figure 1B). The distribution Autoimmune disease, n (%) 17 (12) 30 (11) 0.74 of AKI severity was stage 2 in 43%, stage 3 in Malignancy, n (%) 0.007 57%, and RRT dependence in 9% of patients Melanoma 49(36) 82(30) (Figure 1C). SCr at baseline, AKI diagnosis, Lung 36 (26) 106 (38) peak, and nadir are shown in Figure 1D. An Genitourinary 23 (17) 21 (8) extrarenal irAE, most commonly rash, devel- Other 30 (21) 67 (24) oped before or concomitant with AKI in PPI, n (%) 75(54) 92(33) ,0.001 a 43% of cases (Figure 1E). ICPi n (%) Anti–CTLA-4b 44 (32) 48 (17) 0.001 Results of the diagnostic workup per- fi Anti–PD-1c 127 (92) 250 (91) 0.72 formed to evaluate ICPi-AKI, strati ed Anti–PD-L1 10 (7) 13 (4.7) 0.36 by AKI severity, are shown in Figure 2. Combo anti–CTLA-4+anti–PD-1/PD-L1d 39 (28) 35 (13) ,0.001 Most patients (69%) were receiving a Data are shown as median (IQR) and n (%). CHF, congestive heart failure; COPD, chronic obstructive concomitant medication known to cause pulmonary disease; IV, stage four; CTLA-4, cytotoxic T lymphocyte–associated antigen 4; PD-1, TIN, including antibiotics (9%), nonsteroi- programmed cell death 1; PD-L1, programmed death-ligand 1; Combo, combination. fl aDenotes all ICPis ever received. dal anti-in ammatory drugs (NSAIDs; bIpilimumab was the ICPi agent in 98% of those who received an anti–CTLA-4 antibody. 22%), and PPIs (54%) (Figure 2A). A con- cNivolumab or pembrolizumab was the anti–PD-1 antibody in 49% and 42% of patients. d comitant and potentially nephrotoxic che- Ipilimumab/nivolumab was the combination therapy regimen in 75% of cases and 66% of controls. motherapeutic agent was identified in 6% of patients; however, in each case the AKI was not violated. All comparisons are two-tailed, with P,0.05 was attributed to the ICPi (Supplemental Table 5). Most considered significant. patients (79%) did not have eosinophilia (Figure 2B). The urine protein-to-creatinine ratio was $0.3 g/g in 71% of patients (Figure 2C). Urine dipstick was positive for leuko- RESULTS cyte esterase and pyuria was noted on the urine sediment in approximately half of the patients (Figure 2, D and E). None Baseline Characteristics and Risk Factors for ICPi-AKI of these characteristics differed significantly according to Baseline characteristics for patients with ICPi-AKI (n=138) AKI severity. and controls (n=276) are shown in Table 1. The distributions Renal biopsy was performed in 60 (43%) patients, 56 (93%) of age and sex were similar in cases and controls. Most patients of whom had acute TIN as the dominant lesion. The remaining in both groups were receiving an ICPi for either melanoma or four patients had minimal change disease with acute tubular lung cancer. Compared with controls, patients with ICPi-AKI injury, ANCA-negative pauci-immune crescentic GN, anti– had a lower median baseline eGFR, were more likely to glomerular basement membrane disease, and C3 GN. Histologic be receiving a proton pump inhibitor (PPI), and were features of biopsied patients with TINare shown in Supplemental more likely to be receiving combination therapy with an Table 6. Biopsied and nonbiopsied patients had similar clinical anti-cytotoxic T lymphocyte–associated antigen 4 antibody features of ICPi-AKI (Supplemental Figures 1 and 2). and an anti-programed cell death 1 or anti-programmed death-ligand 1 antibody. Each of these risk factors remained Treatment of ICPi-AKI associated with development of ICPi-AKI in multivariable ICPi therapy was held at AKI diagnosis in 134 (97%) patients, models adjusted for each other along with age, sex, and and 119 (86%) received corticosteroids. Among those who

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Table 2. Risk factors for ICPi-AKI Odds Ratio (95% Conﬁdence Interval) Baseline Variables for ICPi-AKI Univariate Multivariate Forest Plot Age (per 10 years) 1.08 (0.92 to 1.26) 0.91 (0.75 to 1.11) Female 1.08 (0.71 to 1.64) 1.05 (0.67 to 1.65) Prior autoimmune disease 1.15 (0.61 to 2.18) 1.08 (0.55 to 2.11) eGFR, per 30 ml/min per 1.73 m2 decline 1.67 (1.27 to 2.17) 1.99 (1.43 to 2.76) PPI use 2.38 (1.57 to 3.62) 2.85 (1.81 to 4.48) Combination ICPi therapy 2.71 (1.62 to 4.53) 3.88 (2.21 to 6.81)

012345 The full multivariable model was adjusted for the covariates listed in the table. received steroids, the median time from doubling of SCr to initi- same ICPi agent implicated in the initial AKI episode, and 39% ation of steroids was 4 (IQR, 1–12) days. Intravenous pulse steroids of patients were receiving steroids at the time of rechallenge. were used in 36 (30%) patients. The median initial oral steroid Recurrent ICPi-AKI occurred in 23% of rechallenged patients dose in prednisone equivalent units was 60 (IQR, 60–80) mg/d. (Figure 4). Patients who developed recurrent ICPi-AKI had a Eleven (9%) patients received additional immunosuppression shorter latency period between the initial AKI episode and beyond steroids. Additional treatment-related details are rechallenge (Table 4). shown in Table 3 and Supplemental Tables 7 and 8. Patient Survival Kidney Recovery after ICPi-AKI Patients with no kidney recovery had a higher mortality than Complete, partial, and no kidney recovery after ICPi-AKI those with complete or partial kidney recovery (Figure 5A). occurred in 40%, 45%, and 15% of patients, respectively, Because early death after AKI precludes kidney recovery, we and the distribution did not differ significantly on the basis also performed a sensitivity analysis limited to patients who of AKI severity (Figure 3A). Similarly, there was no difference survived more than 2 weeks after ICPi-AKI, and found similar in recovery between biopsied and nonbiopsied patients results (Figure 5B). In multivariable models, the absence of (Supplemental Figure 3). Among the 13 patients who required kidney recovery remained an independent predictor of in- RRT, partial (n=4) or complete (n=2) kidney recovery occurred creased mortality (Figure 5, C and D). Absence of kidney re- in six (46%) patients. covery was also independently associated with mortality in the In a multivariable model, the presence of a concomitant subgroup of renal biopsied patients (Supplemental Figure 5). extrarenal irAE was associated with a lower odds of achieving complete kidney recovery (Figure 3B). Conversely, simultaneous receipt of a TIN-causing medication and treatment with steroids DISCUSSION were each associated with a greater odds of complete recovery. Similar results were obtained in the subgroup of patients who In this multicenter, retrospective cohort study of 138 patients underwent renal biopsy, although treatment with steroids did with ICPi-AKI, the largest conducted to date, we provide several not reach statistical significance (Supplemental Figure 4). key insights into the clinical features and outcomes of ICPi-AKI. The more favorable outcome observed in patients taking a First, we identified lower baseline eGFR, PPI use, and combi- concomitant TIN-causing medication was driven predomi- nation therapy with anti-cytotoxic T lymphocyte–associated nantly by antibiotics and NSAIDs (Supplemental Table 9). antigen 4 and anti-programed cell death 1/anti-programmed Although treatment with steroids was associated with a greater death-ligand 1 antibodies as independent risk factors for odds of complete kidney recovery, no discernable differences in development of ICPi-AKI. Second, we confirm and expand the steroid regimen were observed between patients who achieved on initial observations by our group7 and others8,9,12 on the complete recovery versus those who did not (Table 3). Finally, clinical features of ICPi-AKI, including the variable and often among patients with biopsy-confirmed TIN, no histologic prolonged delay between ICPi initiation and development of feature was associated with kidney recovery, including the AKI, and the frequent rate of extrarenal irAEs occurring con- presence/severity of granulomatous features, tissue eosinophilia, comitantly or immediately preceding the AKI. Third, we con- interstitial fibrosis, or glomerulosclerosis (Supplemental Table 10). firm that TIN is the dominant lesion in patients with ICPi-AKI, occurring in 93% of biopsied patients. Fourth, we found that Rechallenge of Patients with ICPi-AKI patients who have concomitant extrarenal irAEs have a lower Rechallenge with an ICPi was attempted in 31 (22%) patients likelihood of kidney recovery, whereas those receiving treat- at a median of 1.8 (IQR, 1.2–11.0) months after the diagnosis ment with a concomitant TIN-causing medication, as well as of ICPi-AKI. Most patients (87%) were rechallenged with the those treated with steroids, have a higher likelihood of recovery.

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ABWeeks Between ICPi Initiation Weeks Between Last ICPi Cycle and AKI Diagnosis and AKI Diagnosis 35 100 60 100 90 90 30 50 80 80 25 Frequency Frequency 70 70 40 Cumulative Cumulative 60 20 60 50 30 50 15 40 40

Frequency (%) 20 Frequency (%) Cumulative (%) 10 30 Cumulative (%) 30 20 20 5 10 10 10 0 0 0 0 ≤ ≤ 1 1-2 2-4 4-6 6-8 8-10 >10 1 1-5 5-10 >90 10-1515-2020-3030-4040-5050-6060-7070-8080-90 Time (weeks) Time (weeks)

CDAKI Severity Serum Creatinine Trend 5 60

50 4

40 3

30 2

Frequency (%) 20

Serum Creatinine (mg/dl) 1 10

0 0 Stage 2 Stage 3 RRT Baseline Diagnosis Peak Nadir

E Non–Renal Immune Related Adverse Events 50 Prior to AKI 45 Concomitant with AKI 40 35 30 25 20

Frequency (%) 15 10 5 0 ≥ 1 irAE Rash Colitis Hepatitis Pneumonitis Thyroid Hypophysitis Other Disease

Figure 1. Clinical features of ICPi-AKI. (A) The number of weeks between ICPi initiation and AKI diagnosis. (B) The number of weeks between the last ICPi cycle and AKI diagnosis. (C) The distribution of AKI severity according to the Kidney Disease Improving Global Outcomes criteria. (D) The SCr trend (mean6SEM). Baseline SCr refers to the value immediately preceding ICPi initiation; diagnosis SCr refers to the value when the patient ﬁrst fulﬁlled criteria for ICPi-AKI (doubling of SCr or need for RRT); peak SCr refers to the highest value during the AKI episode; and nadir SCr refers to the lowest value achieved within 3 months after the AKI episode (excluding values obtained during RRT). (E) The frequency of extrarenal irAEs occurring before (.14 days before) or concomitantly (within 14 days before or after) with the AKI.

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A Concomitant Medications D Blood on UA 70 70 Stage 2 AKI (n=59) Stage 2 AKI (n=51) 60 Stage 3 AKI (n=79) 60 Stage 3 AKI (n=70) All (n=138) All (n=121) 50 50

40 40

30 30 Frequency (%) 20 Frequency (%) 20

10 10

0 0 ≥ 1 Abx NSAIDs PPIs ≥1+ Neg/Trace 1+ 2+ ≥3+

B Eosinophilia (cells per µL) E Leukocyte Esterase on UA 60 90 Stage 2 AKI (n=57) Stage 2 AKI (n=51) 80 Stage 3 AKI (n=77) 50 Stage 3 AKI (n=70) 70 All (n=134) All (n=121) 60 40 50 30 40

30 Frequency (%) 20 Frequency (%) 20 10 10 0 0 ≥500 <500 500– 1000– >1500 ≥1+ Neg/Trace 1+ 2+ ≥3+ 1000 1500

C UPCR (g/g) F Pyuria (#WBCs per HPF) on UA 80 70 Stage 2 AKI (n=48) 70 Stage 2 AKI (n=35) 60 Stage 3 AKI (n=49) Stage 3 AKI (n=67) 60 All (n=84) 50 All (n=115) 50 40 40 30 30 Frequency (%) Frequency (%) 20 20

10 10

0 0 ≥0.3 <0.3 0.3-1.0 1.1-3 >3 ≥5 <5 5 - 20 >20

Figure 2. Clinical features of ICPi-AKI, stratiﬁed by AKI severity. (A) The frequency of concomitant potential TIN-causing medications taken within 2 weeks preceding ICPi-AKI. (B–F) The distribution of eosinophilia, proteinuria, dipstick hematuria, leukocyte esterase, and pyuria in patients with ICPi-AKI, respectively. Abx, antibiotic; HPF, high-power ﬁeld; Neg, negative; UA, urinalysis; UPCR, urine protein-to- creatinine ratio; WBCs, white blood cells.

Fifth, we found that most patients rechallenged with an ICPi Our ﬁndings are consistent with and expand on prior stud- did not develop recurrence of ICPi-AKI. Finally, we found that ies of ICPi-AKI. We identiﬁed three independent risk factors failure to achieve kidney recovery after an episode of ICPi-AKI for ICPi-AKI: lower baseline eGFR, combination ICPi ther- is associated with increased mortality. apy, and PPI use. CKD is a well recognized risk factor for AKI

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Table 3. Treatment of ICPi-AKI with glucocorticoids, stratified by renal recovery Complete Recovery Partial or No Recovery Treatment Variable All (n=119) P Value (n=53) (n=66) SCr at GC initiation, mg/dl 3.01 (2.25–4.48) 3.34 (2.29–4.63) 2.89 (2.24–3.81) 0.44 Required RRT at GC initiation, n (%) 3 (3) 1 (2) 2 (3) 0.99 Treatment delay, da 3(0–8) 3 (1–8) 3 (0–8) 0.70 Received IV pulse GC, n (%) 36(30) 19(36) 17(26) 0.32 Grams of solumedrol 1.00 (0.38–2.03) 1.00 (0.38–1.50) 1.0 (0.41–2.88) 0.99 Initial daily oral GC dose (mg of prednisone) 60 (60–80) 60 (60–80) 60 (60–80) 0.97 Days at initial oral GC dose 7 (5–12) 7 (5–10) 7 (5–13) 0.73 Days at .20 mg oral prednisone 28 (16–47) 26 (16–39) 31 (17–49) 0.52 Cumulative oral GC dose in first 2 wk (mg of prednisone) 780 (600–980) 775 (658–955) 780 (570–980) 0.78 Days of oral GC 63 (32–107) 62 (35–98) 67 (28–119) 0.96 Received non-GC immunosuppressant, n (%)b 11 (9) 4 (8) 7 (11) 0.75 Nadir SCr after treatment, mg/dlc 1.40 (1.06–1.73) 1.08 (0.9–1.40) 1.6 (1.40–1.90) ,0.001 Data are shown as median (IQR) and n (%). GC, glucocorticoids; IV, intravenous. aDenotes time from doubling of SCr to initiation of GCs. bNon-GC immunosuppression included mycophenolate mofetil (n=7), rituximab (n=2), cyclophosphamide (n=1), and eculizumab (n=1). cDefined as the lowest value achieved within 3 months after the AKI episode (excluding values obtained during RRT). across a variety of settings.13,14 Although relatively few pa- reserve rather than a true increased propensity to immuno- tients in our study had advanced CKD, these patients appeared logic injury. Nonetheless, patients with advanced CKD receiv- to be at greatly increased risk of ICPi-AKI (Tables 1 and 2). It is ing ICPi therapy should have renal function monitored likely that this finding was a consequence of reduced renal closely. Our finding that combination ICPi therapy was

60 A Stage 2 AKI (n=59) Stage 3 AKI (n=79) 50 Entire cohort (n=138)

Frequency (%) 20

0 Complete Recovery Partial Recovery No Recovery B Odds Ratios (95% CIs) for Complete Renal Recovery Variable Univariate Multivariable Forest Plot Age (per 10 yrs) 1.04 (0.77–1.39) 1.19 (0.87–1.66) Female 0.89 (0.44–1.79) 0.94 (0.44–2.01) Combination ICPi therapy1 1.44 (0.68–3.04) 1.95 (0.83–4.63) Fold increase in baseline SCr 1.00 (0.86–1.16) 0.96 (0.81–1.13) Concomitant irAE with AKI 0.41 (0.17–0.95) 0.32 (0.12–0.80) Concomitant Drug2 2.51 (1.13–5.56) 2.66 (1.14–6.19) Treated with glucocorticoids 4.14 (1.14–14.97) 5.55 (1.41–21.81)

0246810

Figure 3. Renal recovery after ICPi-AKI. (A) The frequency of complete, partial, and no kidney recovery after an episode of ICPi-AKI. Complete recovery was defined as a return of SCr to ,0.35 mg/dl of the baseline value, and partial recovery was defined as a return of SCr to .0.35 mg/dl but less than twice the baseline value, or liberation from RRT. (B) Univariate and multivariable adjusted odds ratios (and 95% confidence intervals) for achievement of complete kidney recovery. 1Combination ICPi therapy refers to treatment with both an anti–CTLA-4 and an anti–PD-1/PD-L1 antibody. 2Refers to concomitant use of potential TIN-causing medications, including antibiotics, NSAIDs, and PPIs within 2 weeks prior to the diagnosis of ICPi-AKI. 95% CI, confidence interval; CTLA-4, cytotoxic T lymphocyte–associated antigen 4; PD-1, programmed cell death 1; PD-L1, programmed death-ligand 1.

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138 AKI

9 improved 4 unknown 119 (86%) steroids 19 (14%) no steroids 3 hospice 2 contraindicated 1 lost to follow-up

16 (13%) 51 (43%) 52 (44%) 5 (26%) 11 (58%) 3 (16%) no partial complete no partial complete recovery recovery recovery recovery recovery recovery

31 (22%) re-challenged

24 (77%) no AKI 7 (23%) AKI

1 (14%) 1 (14%) 5 (71%) no partial complete recovery recovery recovery

Figure 4. Flow chart indicating rates of treatment with steroids, kidney recovery, rechallenge, and recurrence of ICPi-AKI. associated with an increased incidence of AKI was also noted in More interesting is the association we detected between our prior analysis of clinical trial data.7 The paradigm of in- ICPi-AKI and PPI use. PPIs are known to cause TIN, albeit creased risk of irAEs with combination therapy extends to ex- rarely.16,17 However, given the high prevalence of their use, trarenal organs as well, including the skin, liver, and endocrine PPIs are now one of the most common causes of drug-induced system,1,15 and likely reﬂects enhanced stimulation of autor- TIN.18 There is likely a complex interplay between drugs eactive T cells induced by dual immune checkpoint blockade. known to cause TIN, like PPIs, and ICPis. ICPis alone are

Table 4. Rechallenge with an ICPi after ICPi-AKI Variable All Rechallenged (n=31) Recurrent AKI (n=7) No AKI (n=24) P Value Months from AKI to rechallenge 1.80 (1.23–10.97) 1.4 (0.73–1.63) 2.05 (1.48–13.95) 0.03 Complete response, n (%) 16 (52) 2 (29) 14 (58) 0.22 SCr at rechallenge, mg/dl 1.30 (1.11–2.00) 1.30 (1.22–1.60) 1.39 (1.11–2.01) 0.98 On GC at rechallenge, n (%) 12 (39) 3 (43) 9 (38) 0.99 Prednisone dose, mg/d 10 (5–15) 10 (5–10) 10 (5–20) 0.91 Rechallenged with same ICPi, n (%) 27 (87) 7 (100) 20 (83) 0.55 Months from rechallenge to AKI NA 1.53 (0.60–4.93) NA NA SCr at recurrent AKI, mg/dl NA 2.70 (1.71–4.80) NA NA Age at ICPi initiation, yr 61 (57–71) 59 (58–61) 68 (56–71) 0.29 Female, n (%) 8 (26) 1 (14) 7 (29) 0.64 Autoimmune disease, n (%) 2 (6) 0 (0) 2 (8) 0.99 Extrarenal irAE, n (%) 17 (55) 5 (71) 12 (50) 0.41 Stage 3 AKI, n (%) 13 (42) 2 (29) 11 (46) 0.67 Biopsied, n (%) 12 (39) 3 (43) 9 (38) 0.99 Data are shown as median (IQR) and n (%). GC, glucocorticoids; SCr, serum creatinine; irAE, immune-related adverse event.

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A B 100 100 Renal recovery Renal recovery 80 80

60 60 No renal recovery

40 No renal recovery 40 Survival (%) Survival (%)

20 20 P<0.001 by log–rank test P=0.004 by log–rank test 0 0 02460246 Time (months) Time (months) No. at risk No. at risk R 117 98 79 65 R 112 98 79 65 NR 21 10 8 6 NR 15 10 8 6

C D Hazard Ratio (95% CIs) for Survival following AKI Hazard Ratio (95% CIs) for Survival following AKI Variable Univariate Multivariable Forest Plot Variable Univariate Multivariable Forest Plot

Age (per 10 yrs) 0.89 (0.71–1.12) 0.94 (0.74–1.20) Age (per 10 yrs) 0.89 (0.70–1.14) 0.93 (0.71–1.21)

Female 0.91 (0.52–1.59) 1.06 (0.60–1.89) Female 1.00 (0.55–1.83) 1.10 (0.59–2.03)

eGFR1 1.08 (0.75–1.57) 0.93 (0.64–1.34) eGFR1 1.17 (0.77–1.76) 1.03 (0.68–1.56)

Stage 3 (vs. 2) AKI 1.41 (0.81–2.44) 1.34 (0.75–2.37) Stage 3 (vs. 2) AKI 1.31 (0.72–2.35) 1.23 (0.67–2.27)

Non–recovery of AKI2 4.08 (2.22–7.49) 3.99 (2.12–7.51) Non–recovery of AKI2 2.81 (1.34–5.87) 2.69 (1.26–5.78)

0123456 0123456

Figure 5. Kidney recovery status predicts overall survival. (A) Kaplan–Meier 6-month overall survival curves, stratified by kidney recovery status, starting at the time of development of ICPi-AKI (median duration of follow-up was 29 [IQR, 10–67] weeks). (B) Similar Kaplan–Meier survival curves but limited to patients who survived for at least 2 weeks after the development of ICPi-AKI. (C and D) Univariate and multivariable adjusted hazard ratios for 6-month mortality. 1Refers to per 30 ml/min per 1.73 m2 decline. 2The reference group is partial or complete recovery of AKI. 95% CI, 95% confidence interval; NR, no recovery; R, recovery. sufficient to induce autoimmunity (including TIN) in humans7; leukocyte esterase on urine dipstick) were absent in 29% and however, it is notable that a large proportion of previously 45% of cases, respectively. Finally, an extrarenal irAE occurred reported patients with ICPi-AKI were also receiving drugs before or concomitantly with the AKI in 43% of cases. Thus, known to cause TIN, including NSAIDs, antibiotics, and no clinical features reliably distinguish ICPi-AKI from other PPIs.7,8 Similarly, we found that nearly 70% of the patients with causes of AKI. These findings are of particular importance in ICPi-AKI in this study were receiving a potential TIN-causing patients with cancer, where AKI commonly occurs because medication, including PPI use in over 50% of the patients. of ischemic or nephrotoxic acute tubular injury/necrosis.20 These findingssuggestthatICPitreatmentcanleadtolossof Guidelines published by the American Society of Clinical tolerance via activation or reactivation of drug-specific T cells Oncology discourage renal biopsy in lieu of empirical glu- in some patients. Thus, PPIs should be used with caution in cocorticoid treatment when ICPi-AKI is suspected.21 Given patients receiving ICPi treatment, and should likely be discon- the lack of specific clinical features to distinguish ICPi-AKI tinued in those who develop ICPi-AKI. from other causes of AKI, this approach runs the risk of We found that the clinical features of ICPi-AKI largely mir- inappropriately exposing patients with other histologic lesions ror those of other causes of drug-associated TIN,18,19 with the to glucocorticoids. Underscoring this notion is a recent case notable exception of the variable and often prolonged latency series in which five out of ten patients with suspected ICPi-AKI between drug initiation and AKI. The majority of patients had were found to have acute tubular injury/necrosis on biopsy.12 An subnephrotic proteinuria and pyuria at the time of ICPi-AKI. additional and likely greater risk is that ICPi therapy may be Neither finding, however, was highly sensitive for the diagno- inappropriately discontinued in cases where AKI was errone- sis: proteinuria ($0.3 g/g) and pyuria (more than a trace of ously attributed to the ICPi. The clinician must weigh the risks

JASN 31: ccc–ccc,2020 Immune Checkpoint Inhibitor–Associated AKII 9 CLINICAL RESEARCH www.jasn.org and benefits of renal biopsy each patient. Patients treated with among those who developed recurrent AKI (three out of ICPis are often ill with multiple comorbidities, which can make seven; 43%) versus those who did not (nine out of 24; 38%); biopsy challenging and higher risk. However, given the lack however, because of the low event rate of recurrent AKI, these of specific clinical and laboratory features, we and others22 findings should be interpreted cautiously. Patients developing feel that biopsy should be strongly considered when feasible, recurrent ICPi-AKI were rechallenged sooner after the initial particularly when alternative causes of AKI exist. ICPi-AKI episode, suggesting reinitiating of ICPis should be We found that TIN was the dominant histologic lesion, delayed if feasible. occurring in 93% of biopsied patients. These findings are Failure to recover from ICPi-AKI was associated with re- consistent with prior reports.7,8 Importantly, other im- duced survival. Although this may not be unexpected,27 it mune-mediated lesions have also been reported, including stands in contrast to the experience with irAEs in general. In podocytopathies and pauci-immune GN.9 In this study, we patients with melanoma, neither development of an irAE re- document four additional cases of ICPi-AKI due to glomeru- quiring immunosuppression nor the need to discontinue ICPi lar disease. These findings further highlight the importance of therapy because of a severe irAE was associated with decreased obtaining a renal biopsy in patients with suspected ICPi-AKI. survival.28,29 However, ICPi-AKI, unlike most other irAEs, can Most patients with ICPi-AKI had partial (45%) or com- result in irreversible organ damage even after immunosuppres- plete (40%) recovery of renal function. The presence of a con- sion has led to cessation of immunologic activity. This may be comitant irAE was associated with a worse renal prognosis. partly attributable to the indolent nature of TIN and the poor This may be the result of a greater state of immune activation sensitivity of SCr for early kidney damage, which together often in these patients that was less responsive to discontinuation of allow TIN to continue unabated for extended periods before ICPi therapy and immunosuppression. It is also possible that being recognized. The increased mortality associated with fail- complications from extrarenal irAEs (e.g., volume depletion ure to recover from ICPi-AKI may reflect the limited cancer from colitis, or impaired renal perfusion owing to myocardi- therapeutic options for patients with persistently impaired re- tis) led to additional tubular injury and impaired kidney renal function, and stresses the importance of early recognition covery. Interestingly, ICPi-AKI cases that occurred in patients and treatment of this entity before irreversible kidney damage receiving a concomitant TIN-causing medication had a greater occurs. probability of complete kidney recovery. This may reflect T cell Although our study is the largest to date and provides reactivity to the drug rather than to endogenous autoantigens, several key insights into ICPi-AKI, we acknowledge several in which case cessation of the offending NSAID, antibiotic, or limitations. We focused on patients who had at least a doubling PPI would lead to a more rapid attenuation of immunologic of SCr or the need for RRT because we were interested in the activity.23 most clinically relevant episodes of ICPi-AKI. However, our The treatment of drug-induced TIN with glucocorticoids is findings may not be generalizable to patients with more mild controversial, with data limited to conflicting observational ICPi-AKI. Additionally, it is possible that some nonbiopsied studies.19,24 The unique proposed mechanisms of ICPi-AKI,25 patients had alternative causes of AKI not directly attributable in which the effects of immune stimulation persist after ICPi to the ICPi (e.g., acute tubular necrosis), and were misadjudicated discontinuation, along with the experience of managing extra- by the treating clinicians as having ICPi-AKI. It is, however, renal irAEs,21 provides the rationale for glucocorticoid therapy reassuring that clinical features were similar among biopsied in ICPi-AKI. In our study, treatment with glucocorticoids was and nonbiopsied patients. Potential TIN-causing medications independently associated with complete kidney recovery. were only reported if administered within 2 weeks of the AKI However, we were not able to identify any specific features of episode. It is therefore possible that in a small number of the glucocorticoid regimen that were associated with greater patients a medication discontinued more than 2 weeks before treatment efficacy. This is not unexpected, as glucocorticoid AKI could have initiated the TIN episode. Cases and controls dosing and tapering are intrinsically linked to and confounded were not selected from the same at-risk population because by comorbidities, disease severity, and response to treatment. control patients were selected from two sites in Boston, whereas Such confounding factors have precluded the ability to define cases were selected from 18 sites from across the country. How- the optimal glucocorticoid regimen for drug-induced TIN in ever, the two sites from which control patients were selected general.26 are each large academic cancer centers that treat highly diverse The decision to rechallenge with an ICPi after an episode of patient populations. Further, control patients initiated ICPis ICPi-AKI, particularly when the AKI is severe, carries enor- contemporaneously with cases and were selected at random mous weight. This decision is currently rendered more diffi- and without any inclusion or exclusion criteria applied other cult because of limited data on the risk of recurrent AKI. Our than the absence of AKI. Finally, although our hypotheses were study provides outcomes on 31 patients with ICPi-AKI who prespecified, we cannot exclude the possibility of a type 1 error underwent ICPi rechallenge. Despite 87% of patients receiving because of the large number of tests performed. the same ICPi implicated in the initial AKI episode, 77% of In conclusion, we provide new data of interest to both cli- those rechallenged did not develop recurrent AKI. We found nicians and researchers, including risk factors for ICPi-AKI no difference in the frequency of steroid use at rechallenge development, determinants of treatment response, and the

10 JASN JASN 31: ccc–ccc,2020 www.jasn.org CLINICAL RESEARCH recurrence rate of AKI after ICPi rechallenge. Further ad- Supplemental Appendix 1. Data collected on cases. vancement in the care of patients with ICPi-AKI will require Supplemental Table 1. List of collaborating institutions. multicenter collaboration to collect biologically relevant samples Supplemental Table 2. ICPi initiation by year, cases versus that can be interpreted in the context of clinical outcomes. Dis- controls. covery of biomarkers for ICPi-AKI could lead to early diagnosis, Supplemental Table 3. Baseline characteristics of biopsied and assist in discriminating ICPi-AKI from other causes of AKI, and nonbiopsied patients with ICPi-AKI. help inform the risk of recurrent ICPi-AKI with rechallenge. Supplemental Table 4. Risk factors for ICPi-AKI among biopsied patients. Supplemental Table 5. Concomitant chemotherapeutic nephrotoxins. ACKNOWLEDGMENTS Supplemental Table 6. Histologic features of biopsied patients with TIN. Concept and design: all authors. Acquisition, analysis, or interpretation Supplemental Table 7. Treatment of ICPi-AKI, stratified by biopsy of data: all authors. Drafting of the manuscript: Dr. Cortazar and status. Dr. Leaf. Critical revision of the manuscript for important intellectual Supplemental Table 8. Clinical features of patients receiving im- content: all authors. Statistical analysis: Dr. Cortazar, Ms. Kibbelaar, munosuppression in addition to steroids (n=11). fi and Dr. Leaf. Preparation of gures and tables: Dr. Cortazar, Supplemental Table 9. Odds ratios for complete kidney recovery fi Ms. Kibbelaar, and Dr. Leaf. All authors approved the nal version of according to concomitant potential TIN-causing medications. the manuscript, and all are accountable for all aspects of the submitted Supplemental Table 10. Odds ratios for complete kidney recovery work. according to histologic features in patients with TIN. The authors thank Dino Mazzarelli, J.D., from Partners Healthcare Supplemental Figure 1. Clinical features of ICPi-AKI in biopsied Research Management, for his invaluable assistance coordinating the patients with TIN. respective data transfer and use agreements with each institution. Supplemental Figure 2. Clinical features of ICPi-AKI in patients with and without biopsy-proved TIN. DISCLOSURES Supplemental Figure 3. Kidney recovery after ICPi-AKI among biopsied versus nonbiopsied patients. Supplemental Figure 4. Factors associated with kidney recovery Dr. Assal reports grants from NIH/NCI Cancer Center, during the conduct of the study; personal fees from Alpha Insights, personal fees from Boston after ICPi-AKI among biopsied patients. Biomedical, personal fees from Incyte Corporation, grants from Incyte Cor- Supplemental Figure 5. Kidney recovery status predicts overall poration, outside the submitted work. Dr. Glezerman reports other from Pfizer survival in biopsied-only patients. Inc., outside the submitted work. Dr. Gupta reports grants from NIH, during the conduct of the study. Dr. Johnson reports other from Array Biopharma, grants and other from BMS, grants and other from Incyte, other from Merck, REFERENCES other from Novartis, outside the submitted work. Dr. Leaf reports grants from BioPorto Diagnostics, outside the submitted work. Dr. Marrone reports other 1. Larkin J, Chiarion-Sileni V, Gonzalez R, Grob JJ, Cowey CL, Lao CD, from AstraZeneca, other from Compugen, other from Takeda, outside the et al.: Combined nivolumab and ipilimumab or monotherapy in un- fi submitted work. Dr. Vijayan reports personal fees from Sano -Aventis, outside treated melanoma. NEnglJMed373: 23–34, 2015 the submitted work. All other authors report no relevant disclosures. 2. Gandhi L, Rodríguez-Abreu D, Gadgeel S, Esteban E, Felip E, De Angelis F, et al.; KEYNOTE-189 Investigators: Pembrolizumab plus chemotherapy in metastatic non-small-cell lung cancer. 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AFFILIATIONS

1Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts; 2New York Nephrology Vasculitis and Glomerular Center, Albany, New York; 3Division of Renal Medicine, Brigham and Women’s Hospital, Boston, Massachusetts; 4Renal Service, Memorial Sloan Kettering Cancer Center and Weil Cornell Medical College, New York, New York; 5Section of Nephrology, The University of Texas MD Anderson Cancer Center, Houston, Texas; 6Dana Farber Cancer Institute, Boston, Massachusetts; 7Division of Nephrology, Mayo Clinic, Rochester, Minnesota; 8Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut; 9Division of Nephrology, University of Toronto, University Health Network, Ontario, Canada; 10Division of Nephrology and 11Division of Hematology-Oncology, Columbia University Medical Center, New York, New York; 12Division of Nephrology, Washington University in St. Louis, St. Louis, Missouri; 13Division of Nephrology, University of Virginia School of Medicine, Charlottesville, Virginia; 14Division of Nephrology, Duke University Medical Center, Durham, North Carolina; 15Divisions of Nephrology and Hematology-Oncology, The University of Alabama at Birmingham, Birmingham, Alabama; 16Division of Nephrology, University of Washington, Seattle, Washington; 17Division of Nephrology, Hypertension and Electrolytes, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania; 18Division of Hematology and Oncology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California; 19Division of Hematology and Oncology, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; 20Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland; 21Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida; 22Division of Hematology-Oncology, Vanderbilt University Medical Center, Nashville, Tennessee; and 23Division of Oncology, Massachusetts General Hospital, Boston, Massachusetts

12 JASN JASN 31: ccc–ccc,2020 Supplemental Material

Cortazar et al. Clinical Features and Outcomes of Immune Checkpoint Inhibitor-associated AKI: a multicenter study

Table of Contents

Supplemental Appendix Data collected on cases

Supplemental Table 1 List of Collaborating institutions

Supplemental Table 2 ICPi initiation by year, cases vs. controls

Supplemental Table 3 Baseline characteristics of biopsied and non-biopsied patients with ICPi-AKI

Supplemental Table 4 Risk factors for ICPi-AKI among biopsied patients

Supplemental Table 5 Concomitant chemotherapeutic nephrotoxins

Supplemental Table 6 Histologic features of biopsied patients with TIN

Supplemental Table 7 Treatment of ICPi-AKI, stratified by biopsy status

Supplemental Table 8 Clinical features of patients receiving immunosuppression in addition to steroids ( n=11)

Supplemental Table 9 Odds ratios for complete renal recovery according to concomitant potential TIN-causing medications

Supplemental Table 10 Odds ratios for complete renal recovery according to histologic features in patients with TIN

Supplemental Figure 1 Clinical features of ICPi-AKI in biopsied patients with TIN

Supplemental Figure 2 Clinical features of ICPi-AKI in patients with and without biopsy-proved TIN

Supplemental Figure 3 RenaI recovery following ICPi-AKI among biopsied versus nonbiopsied patients

Supplemental Figure 4 Factors associated with renaI recovery following ICPi-AKI among biopsied patients.

Supplemental Figure 5 Renal recovery status predicts overall survival in biopsied-only patients

Supplemental Appendix – Data collected on cases

Data collected from each case included age; gender; race; comorbidities, including pre-existing autoimmune disease; baseline serum creatinine (SCr), defined as the value immediately preceding initiation of ICPi therapy; malignancy type; ICPi regimen; occurrence of extrarenal immune-related adverse events (irAEs) prior to or concomitant with ICPi-AKI; concomitant use of tubulointerstitial nephritis-causing medications, including proton pump inhibitors, antibiotics, and nonsteroidal anti-inflammatory drugs within 2 weeks preceding the diagnosis of ICPi-AKI; longitudinal SCr values; urinalysis, urine microscopy, and quantification of proteinuria at the time of AKI; need for renal replacement therapy; glucocorticoid regimen; alternative immunosuppressants administered; and survival status at last follow-up. We also collected pathology reports from all patients who underwent a kidney biopsy. We classified the degree of interstitial fibrosis/tubular atrophy and glomerulosclerosis as none/mild (0-25%), moderate (26- 50%), or severe (>50%). We also collected data on the presence of granulomatous features and tissue eosinophilia. Patients were considered to have tissue eosinophilia if the pathologist noted that eosinophils comprised a prominent component of the interstitial infiltrate.

Collaborating Institution (# patients contributed) Brigham and Women's Hospital/Dana Farber Cancer Institute (14) Boston, MA Columbia University Medical Center (7) New York, NY Duke University (6) Durham, NC Johns Hopkins University (3) Baltimore, MD Massachusetts General Hospital (13) Boston, MA Mayo Clinic (11) Rochester, MN MD Anderson Cancer Center (13) Houston, TX Memorial Sloane Kettering Cancer Center (20) New York, NY University of Alabama Birmingham (5) Birmingham, AL University of California, Los Angeles (3) Los Angeles, CA University of Miami (3) Miami, FL University of Pennsylvania (5) Philadelphia, PA University of Toronto (8) Toronto, ON University of Virginia (6) Charlottesville, VA University of Washington (5) Seattle, WA Vanderbilt University (1) Nashville, TN Washington University in Saint Louis (7) Saint Louis, MO Yale University (8) New Haven, CT

Supplemental Table 1. Collaborating institutions. Eighteen total institutions contributed to patients to the study.

Year of ICPi initiation Cases ( n=138) Control ( n=276) 2011-2012 10 (7.2) 4 (1.4) 2013-2014 17 (12.3) 20 (7.2) 2015-2016 45 (32.6) 144 (52.2) 2017-2018 66 (47.8) 108 (39.1)

Supplemental Table 2. ICPi initiation by year, cases vs. controls

Variable Biopsied Non -biopsied P Value (n=60) (n=78) Age at ICPi initiation (yrs) 64 (58-73) 69 (60-75) 0.047 Female, n (%) 21 (35) 34 (44) 0.38 Race, n (%) 0.90 White 50 (83) 66 (85) Black 4 (7) 6 (8) Asian 1 (2) 2 (3) Comorbidities, n (%) Hypertension 30 (50) 47 (60) 0.30 Diabetes 9 (15) 14 (18) 0.82 CHF 0 (0) 3 (4) 0.26 COPD 2 (3) 4 (5) 0.70 Cirrhosis 0 (0) 2 (2.6) 0.51 Baseline SCr (mg/dL) 0.94 (0.80-1.34) 0.91 (0.80-1.20) 0.34 Baseline eGFR (ml/min) 74 (55-91) 72 (55-88) 0.92 CKD, n (%) 19 (32) 25 (32) 1.00 CKD IV, n (%) 4 (7) 5 (6) 1.00 Autoimmune Disease, n (%) 11 (18) 6 (8) 0.07 Malignancy, n (%) 0.88 Melanoma 20 (33) 29 (37) Lung 15 (25) 21 (27) Genitourinary 10 (17) 13 (17) Other 15 (25) 15 (19) Proton pump inhibitor, n (%) 33 (55) 42 (54) 1.00 ICPi 1, n (%) Anti-CTLA-4 19 (32) 25 (32) 1.00 Anti-PD-1 56 (93) 71 (91) 0.76 Anti-PD-L1 5 (8) 5 (6) 0.75 Combo anti-CTLA-4 + anti-PD-1/ PD-L1 18 (30) 21 (27) 0.71

Supplemental Table 3. Baseline characteristics of biopsied and non-biopsied patients with ICPi-AKI. 1Denotes all ICPis ever received. Abbreviations: Combo, combination; CTLA-4, cytotoxic T-lymphocyte-associated protein 4; ICPi, immune checkpoint inhibitor; PD-1, programmed cell death 1; PD-L1, programmed death-ligand 1; SCr, serum creatinine.

Supplemental Table 4. Risk factors for ICPi-AKI among biopsied patients. The multivariable model was adjusted for all covariates listed in the table. Abbreviations: ICPi, immune checkpoint inhibitor; PPI, proton pump inhibitor.

Concomitant Nephrotoxins n (%) Cisplatin 0 (0) VEGF/TKI 1 7 (5) Other 2 2 (1)

Supplemental Table 5. Concomitant chemotherapeutic nephrotoxins. This table shows the number of patients who received cisplatin, a VEGF/TKI agent, or other potentially nephrotoxic chemotherapeutic agents with 2 weeks prior to ICPi-AKI. Data were available for the entire cohort ( n=138). 1Alectinib ( n=1), bevacizumab ( n=2), bosutinib ( n=1), crizotinib ( n=1), osimertinib ( n=1), and vemurafenib ( n=1); 2Carboplatin ( n=1), dabrafenib ( n=1). Abbreviations: VEGF, vascular endothelial growth factor; TKI, tyrosine kinase inhibitor.

Histologic Feature n (%) Granulomatous Features 11 (20) Tissue Eosinophilia 32 (57) Interstitial Fibrosis/Tubular Atrophy 1 None/Mild 43 (80) Moderate 9 (17) Severe 2 (4) Glomerulosclerosis None/Mild 47 (84) Moderate 5 (9) Severe 4 (7)

Supplemental Table 6. Histologic features of biopsied patients with TIN. n=56. 154 patients with available data on interstitial fibrosis/tubular atrophy. Abbreviations: TIN, tubulointerstitial nephritis.

Treatment Variable All Biopsied Not Biopsied P Value (n=119) (n=53) (n=66) SCr at GC initiation (mg/dL) 3.01 (2.25–4.48) 3.19 (2.53–5.11) 2.81 (2.13–3.97) 0.13 Required RRT at GC initiation, n (%) 3 (3) 3 (6) 0 (0) 0.09 Treatment delay 1 (days) 3 (0–8) 6 (2–14) 2 (0–6) <0.001 Received IV pulse GC, n (%) 36 (30) 15 (28) 21 (32) 0.69 Grams of solumedrol 1.00 (0.38–2.03) 0.75 (0.44–1.75) 1.50 (0.38–2.75) 0.98 Initial daily oral GC dose (mg of 60 (60–80) 60 (60–61) 60 (60–90) 0.63 prednisone) Days at initial oral GC dose 7 (5–12) 7 (5–12) 7 (5–11) 0.38 Days at > 20 mg oral prednisone 28 (16–47) 28 (20–47) 30 (14–44) 0.25 Cumulative oral GC dose in first 2 780 (600–980) 790 (665–951) 780 (570–980) 0.50 weeks (mg of prednisone) Days of oral GC 63 (32–107) 69 (42–102) 54 (28–94) 0.02 Received non-GC immuno- 11 (9) 7 (13) 4 (6) 0.21 suppressant 2, n (%) Nadir SCr after treatment 3 (mg/dL) 1.40 (1.08–1.73) 1.47 (1.09–1.81) 1.39 (1.05–1.64) 0.39

Supplemental Table 7. Treatment of ICPi-AKI, stratified by biopsy status. Data are shown as median (interquartile range) and n (%). 1Denotes time from doubling of SCr to initiation of GCs. 2Non-GC immunosuppression included mycophenolate mofetil ( n=7), rituximab ( n=2), cyclophosphamide ( n=1), and eculizumab ( n=1). 3Defined as the lowest value achieved within 3 months following the AKI episode (excluding values obtained during RRT). Abbreviations: GC, glucocorticoids; RRT, renal replacement therapy; SCr, serum creatinine.

Age/ Cancer Type ICPi Biopsy Alternative Renal Recovery 6 Month Sex Regimen Findings Immuno- Status Survival suppression Status 58F GBM Pembro MMF Partial Deceased 64F Liver Nivo Rituximab Complete Alive 75M Melanoma Ipi+Nivo TIN MMF Partial Deceased 41M Squamous Nivo Pauci-Immune Rituximab Complete Deceased cell lung GN 51F Melanoma Ipi+Nivo+ TIN MMF, Infliximab Partial Alive Pembro 57M Melanoma Ipi+Nivo Anti-GBM GN Cyclophosphamide None Alive 54M Squamous Pembro MMF Complete Alive cell lung 56F Melanoma Pembro + Plasma Exchange, Partial Deceased Durvalumab Eculizumab 63M RCC Nivo TIN MMF Partial Alive 66M RCC Nivo TIN MMF Partial Alive 63M Melanoma Nivo TIN MMF Partial Alive

Supplemental Table 8. Clinical features of patients receiving immunosuppression in addition to steroids ( n=11). Patients with glomerular disease received the immunosuppressant as initial therapy concomitantly with steroids, while patients with biopsy- proven or suspected TIN received the immunosuppressant for resistant disease. Abbreviations: F, female; GBM, glioblastoma multiforme; GC, glucocorticoids; GN, glomerulonephritis; Ipi, Ipilimumab; M, male; MMF, mycophenolate mofetil; Nivo, Nivolumab; Pembro, Pembrolizumab; RCC, renal cell carcinoma; TIN, tubulointerstitial nephritis.

Drug Univariate Odds Ratio (95% CI) Antibiotic 1.87 (0.59–5.90) NSAID 2.02 (0.89–4.58) PPI 1.14 (0.58–2.27)

Supplemental Table 9. Odds ratios for complete renal recovery according to concomitant potential TIN-causing medications. Abbreviations: NSAID, nonsteroidal anti-inflammatory drug; PPI, proton pump inhibitor; TIN, tubulointerstitial nephritis.

Histologic Feature Univariate Odds Ratio (95% CI) Granulomatous TIN 1.73 (0.46-6.56) Tissue Eosinophilia 1.01 (0.34-2.98) Moderate/Severe IFTA 0.47 (0.12-1.74) Moderate/Severe GS 1 1.69 (0.40-7.10)

Supplemental Table 10 . Odds ratios for complete renal recovery according to histologic features in patients with TIN. 1Sum of global and segmental glomerulosclerosis. Abbreviations: GS, glomerulosclerosis; IFTA, interstitial fibrosis and tubular atrophy.

Supplemental Figure 1. Clinical features of ICPi-AKI in patients with biopsy-proven TIN (n=56).

Supplemental Figure 2. Clinical features of ICPi-AKI in patients with and without biopsy- proven TIN. Panel A shows the frequency of concomitant potential TIN-causing medications taken within two weeks preceding ICPi-AKI in patients with and without biopsy-proven TIN. Panels B, C, D, E, and F show the distribution of eosinophilia, proteinuria, hematuria, leukocyte esterase, and pyuria, respectively, in patients with and without biopsy-proven TIN. For all analyses, chi-square testing demonstrated similar distributions between biopsy-proven vs. non- biopsy-proven TIN. Abbreviations: Abx, antibiotic; Bx, biopsy; HPF, high-power field; NSAIDs, nonsteroidal anti-inflammatory drugs; PPIs, proton pump inhibitors; TIN, tubulointerstitial nephritis; UA, urinalysis; UPCR, urine protein-to-creatinine ratio; WBCs, white blood cells.

Supplemental Figure 3. RenaI recovery following ICPi-AKI among biopsied versus nonbiopsied patients . The frequency of complete, partial, and no renal recovery following an episode of ICPi-AKI was similar in biopsied versus non-biopsied patients.

Supplemental Figure 4. Factors associated with renaI recovery following ICPi-AKI among biopsied patients . Univariate and multivariable adjusted odds ratios (and 95% CIs) for achievement of complete renal recovery in biopsied patients only ( n=60). 1Combination ICPi therapy refers to treatment with both an anti-CTLA-4 and an anti-PD-1/PD-L1 antibody. 2Refers to concomitant use of potential TIN-causing medications, including antibiotics, NSAIDs, and PPIs within 2 weeks prior to the diagnosis of ICPi-AKI. Concomitant irAE with AKI was not included in the model due to being a perfect predictor of failure to achieve complete renal recovery among biopsied patients. Abbreviations: CI, confidence interval; CTLA-4, cytotoxic T- lymphocyte-associated protein 4; irAE, immune-related adverse event; NSAID, nonsteroidal anti-inflammatory drug; PD-1, programmed cell death 1 protein; PD-L1, programmed death- ligand 1; PPI, proton pump inhibitor; RRT, renal replacement therapy; SCr, serum creatinine.

Supplemental Figure 5. Renal recovery status predicts overall survival in biopsied-only patients ( n=60). Panel A shows Kaplan-Meier 6-month survival curves, stratified by renal recovery status, starting at the time of development of ICPi-AKI. Panels B shows univariate and multivariable adjusted hazard ratios for 6-month mortality. 1Refers to per 30 ml/min/1.73m 2 decline. Abbreviations: NR, no recovery; R, recovery.