Minimal Residual Disease in Multiple Myeloma

Multiple Myeloma – Pathophysiology and Epidemiology

Multiple myeloma (MM) is a plasma cell malignancy in which abnormal, clonal plasma cells proliferate and accumulate within the bone marrow. These abnormal cells, referred to as myeloma cells, disrupt normal bone marrow function and invade the surrounding bone. Myeloma cells produce and secrete significant quantities of monoclonal protein (M-protein) into the blood and/or urine.1 This increases M-protein and calcium levels, and leads to renal dysfunction, anemia and bone disease. Bone pain is the most common symptom of MM.2

• MM is the second most common hematologic malignancy and accounts for approximately 17% of all hematologic cancers.3 • Every year, an estimated 159,985 new cases of MM are diagnosed globally and 106,105 deaths can be attributed to the disease.4 • MM predominantly affects elderly people; it is most frequently diagnosed in those aged between 65–74 years. MM is more common in males and African Americans compared to females and Caucasians, respectively.5 • The incidence of MM increased by 126% between 1990 and 2016, with the highest rates in Western Europe, North America and Oceania.6 • Overall, the 5-year survival among adults with MM is 50.7%.5

Complete Response Categories in MM7-10 Minimal Residual Disease – Why Assess It? Improvements in therapeutic agents and regimens have driven The treatment of MM has improved significantly over the last decade, the evolution of the International Myeloma Working Group (IMWG) resulting in many patients exhibiting a CR to front-line therapy.10,11 response criteria to include deeper measures of response. The Unfortunately, the disease course of MM is characterized by a pattern definition of a complete response (CR) was first introduced in1998 of recurrent remissions and relapses.1 After an initial CR, many patients and refined in2006 to include stringent CR.7,8 Definitions for molecular inevitably relapse; therefore, MM remains an incurable disease.6,11 and immunophenotypic CR (not shown) were introduced in 2011.9 In 2016, the IMWG was updated to include measurements of minimal Relapses in MM may be attributed to the persistence of minimal residual residual disease (MRD).10 disease (MRD) below the limits of detection by morphological exami- nation.10,12 MRD refers to the persistence of small numbers of myeloma cells that remain in the body after therapy and contribute to relapse and Negative immunofixation on the serum disease progression.10,13 In recent years, increasingly sensitive assays to and urine and disappearance of any soft detect MRD have been developed.13 CR* tissue plasmacytomas and <5% plasma cells in bone marrow aspirates In a retrospective analysis of 3 clinical trials, 40% of patients with MM relapsed within 4 years of achieving a CR14 CR plus normal FLC ratio and absence of clonal cells in bone marrow biopsy by sCR* immunohistochemistry (κ/λ ratio ≤4:1 or Hypothetical Correlation Between Depth of Response and Risk of Relapse ≥1:2 for κ and λ patients, respectively, after counting ≥100 plasma cells) Presentation Relapse 109 108 TTP short Absence of aberrant clonal plasma cells 107 on bone marrow aspirate, ruled out by 6 MRD-negative‡ an assay† with a minimum sensitivity of 10 1 in 105 nucleated cells or higher 105 -5 (i.e. 10 sensitivity) 4 10 Late relapse due 103 to undetectable levels of MRD MRD negativity as defined by NGF 102 or NGS plus disappearance of every TTP long area of increased tracer uptake found 101 ‡ Total number of malignant cells Imaging-positive MRD-negative at baseline or a preceding PET/CT or 10 Lower risk of relapse decrease to less mediastinal blood pool SUV or decrease to less than that of 0 surrounding normal tissue Diagnosis End of TTP therapy MRD negativity in the marrow (NGF or TTP: time to progression NGS, or both) and by imaging as defined Adapted from Paiva B, et al. Blood. 2015;125:3059-3068. ‡ above, confirmed minimum of 1 year Sustained MRD-negative apart. Subsequent evaluations can be used to further specify the duration of negativity (eg, MRD-negative at 5 years)

CR: complete response; sCR: stringent complete response; FLC: free light chain; MRD: minimal residual disease; NGF: next-generation flow; NGS: next-generation sequencing; PET: positron emission tomography; CT: computed tomography; SUV: standardized uptake values

*Response categories require two consecutive assessments before starting any new therapy † Based on flow cytometry (EuroFlow standard operating procedure for MRD detection in multiple myeloma or other validated equivalent method) or next-generation sequencing (LymphoSIGHT platform or validated equivalent method) ‡ Requires a complete response, as defined above Overall PFS hazard ratio forest plot15 Overall OS hazard ratio forest plot15 MRD MRD MRD MRD Study Negative Positive Study Negative Positive

Rawstron et al, 2002 Rawstron et al, 2002 San Miguel et al, 2002 Ferrero et al, 2014 Ferrero et al, 2014 Bakkus et al, 2004 Bakkus et al, 2004 Dal Bó et al, 2013 Dal Bó et al, 2013 Paiva et al, 2011 (CR) Paiva et al, 2011 Paiva et al, 2008 Paiva et al, 2008 Korthals al, 2012 Korthals et al, 2012 Korthals et al, 2013 Korthals et al, 2013 Swedin et al, 1998 (CR) Swedin et al, 1998 (CR) Rawstron et al, 2013 Rawstron et al, 2013 Ludwig et al, 2015 (CR) Roussel et al, 2014 Fukumoto et al, 2016 Fukumoto et al, 2016 Overall HR, 0.57 95% CI, 0.46-0.71, P< .001 Sarasquete et al, 2005 Overall HR, 0.41 95% CI, 0.36-0.48, P< .001

0 0.5 1.0 1.5 2.0 0 1.0 2.0 3.0 4.0 Hazard Ratio for PFS Hazard Ratio for OS

Overall PFS by MRD status15 Overall OS by MRD status15 100 100 2 2 χ1 = 134.4 χ1 = 25.27 P<.001 P<.001 80 80

60 60 MRD- n=599

PFS, % 40 40 MRD- n=660

20 Cumulative Surviving, % 20 MRD+ MRD+ n=613 n=501 0 0 0 2 4 6 8 10 12 0 2 4 6 8 10 12 Time, y Time, y

No. at risk No. at risk MRD Negative 457 214 70 12 1 MRD Negative 508 359 139 26 4 MRD Positive 308 113 28 4 1 MRD Positive 390 250 105 17 5

Hypothetical CorrelationHypothetical Between Correlation MRD Between and Clinical MRD and Outcomes Clincial Outcomes

100 100

MRD-

MRD- Overall Survival, %

MRD+ Progression-Free Survival, % MRD+ 0 0 Time Time

Adapted from Munshi NC, et al. JAMA. 2017;3:28-35 There is a growing body of data that suggests that MRD is prognostic for improved clinical outcomes.15 As such, a patient’s MRD status is now being used as an endpoint in multiple myeloma clinical trials and may potentially guide treatment decisions.10 Features of MRD Detection Methods10,14,16,17

Method Process Sensitivity Important Considerations

• Applicability: 90-100% • Fresh sample necessary Differentiates between normal • Widely available • Less expensive and abnormal plasma cells MFC 10-5–10-6 • Quantitative • Not applicable to extramedullary disease through detection of cell-surface (≥ 8-color) • Fast turnaround time • Not yet standardized marker expression

• Applicability: 43%-75% • Fresh sample not necessary Analysis of VDJ heavy chain • Intermediate availability • More expensive regions for detection of myeloma 10-5–10-6 ASO–PCR • Indirect quantitation • Not applicable to extramedullary disease specific Ig rearrangements • Longer turnaround time • Standardized (EuroMRD)

• More expensive, but costs decreasing • Applicability: ~90% Use of high throughput • Fresh sample not necessary • Limited availability sequencing to detect clonal Ig 10-6 • Not applicable to extramedullary disease NGS • Indirect quantitation VDJ gene rearrangements • Not yet standardized • Longer turnaround time

Automatically identifies • Applicability: 100% • More expensive plasma cells by comparing • Limited availability • Fresh sample necessary NGF 10-6 against reference databases of • Quantitative • Not applicable to extramedullary disease bone marrow • Longer turnaround time • Standardized (EuroFlow)

Permits detection of lesions • Applicability: ~100% • More expensive demonstrating metabolic activity • Intermediate availability • Detects extramedullary disease together with morphologic Variable sensitivity PET/CT • Fast turnaround time • False-negative and false-positive results information and has advantage of with coexisting infection or inflammation detecting extramedullary disease

MRD: minimal residual disease; MFC: Multiparametric flow cytometry; ASO: Allele-specific oligonucleotide; Q-PCR: quantitative polymerase chain reaction; NGS: Next-generation sequencing; PET: positron emission tomography; CT: computed tomography; VDJ: variable diversity joining

Future applications and clinical potential

Relapses in MM may potentially indicate the presence of residual disease. Recently, technological advances in molecular testing, particu- larly in NGF and NGS, and imaging techniques, such as PET/CT, have enabled the detection of myeloma cells with greater sensitivity14, 15 and provided a means to quantitatively assess MRD in MM.

Ongoing studies will continue to define MRD’s value and its role in improving long-term outcomes for patients with MM.10,15,18

Numerous studies have demonstrated the prognostic importance of MRD; however, the standardization of MRD testing, as well as the role of MRD status in driving treatment decisions, is ongoing.15 Large clinical trials that incorporate response-based treatment strategies based on MRD status will be informative and have the potential to define the depth of response required for sustained benefit.10 Future standardized MRD testing techniques may therefore become part of the standard of care for patients with MM.18

References

1. Durie BGM. Multiple Myeloma - Concise Review of the Disease and Treatment Options. 2018 Second Edition. 10. Kumar S, Paiva B, Anderson KC, et al. Lancet Oncol. 2016;17:e328-e346. International Myeloma Foundation. https://www.myeloma.org/sites/default/files/resource/ConciseReview.pdf 11. Fernandez de Larrea C, Jiménez R, Rosiñol L, et al. Bone Marrow Transplant. 2014;49:223-227. Accessed April 11 2019 12. Sarasquete ME, García-Sanz R, González D, et al. Haematologica. 2005;90:1365-1372. 2. Palumbo A and Anderson K. N Engl J Med. 2011;364:1046-1060. 13. Mailankody S, Korde N, Lesokhin AM, et al. Nat Rev Clin Oncol. 2015;12:286-295. 3. Kumar SK, Callander NS, Alsina M, et al. NCCN Guidelines Insights. Multiple Myeloma, Version 3.2018. Paiva B, van Dongen JJ, Orfao A. Blood. 2015;125:3059-3068. Featured Updates to the NCCN Guidelines. J Natl Compr Canc Netw. 2018;16:11–20 14. Munshi NC, Avet-Loiseau H, Rawstron AC, et al. 2017;3:28-35 4. Bray F, Ferlay J, Soerjomataram I, et al. Global Cancer Statistics 2018: GLOBOCAN Estimates of Incidence 15. JAMA Oncol. and Mortality Worldwide for 36 Cancers in 185 Countries. Ca Cancer J Clin. 2018;68:394–424 16. Bai Y, Orfao A, Chim CS. Br J Haematol. 2018;181:11-26 5. NIH SEER Fact Sheet Myeloma. https://seer.cancer.gov/statfacts/html/mulmy.html. Accessed April 11 2019 17. Berger N, Kim-Schulze S, Parekh S. Advances in Experimental Medicine and Biology 1100. 2018. Chapter 9:141-159 6. Cowan AJ, Allen C, Barac A, et al. JAMA Oncol. 2018;4:1221-1227 18. Landgren O, Lu SX, Hultcrantz M. Semin Hematol. 2018;55:44-50 7. Bladé J, Samson D, Reece D, et al. Br J Haematol. 1998;102:1115-1123. 8. Durie BG, Harousseau JL, Miguel JS, et al. Leukemia. 2006;20:1467-1473. 9. Rajkumar SV, Harousseau JL, Durie B, et al. Blood. 2011;117:4691-4695. USA-171-80782