Safety and Efficacy of Rilzabrutinib (PRN1008), an Oral Bruton
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#S316 Safety and Efficacy of Rilzabrutinib (PRN1008), an Oral Bruton Tyrosine Kinase Inhibitor, in Relapsed/Refractory Patients With Primary or Secondary Immune Thrombocytopenia: Phase I/II Adaptive Study David J. Kuter,1 Ralph V. Boccia,2 Eun-Ju Lee,3 Merlin Efraim,4 Nikolay Tzvetkov,5 Jiri Mayer,6 Marek Trněný,7 Milan Kostal, MD,8 Roman Hajek,9 Vickie McDonald,10 Olga Bandman,11 Regan Burns,11 Ann Neale,11 Dolca Thomas,11 and Nichola Cooper12 1Massachusetts General Hospital Cancer Center, Boston, MA, USA; 2Center for Cancer and Blood Disorders, Bethesda, MD, USA; 3Department of Medicine, Weill Cornell Medical College-New York, Presbyterian Hospital, New York, NY, USA; 4Multiprofile Hospital for Active Treatment Sveta Marina EAD, Bulgaria; 5MHAT Dr. Georgi Stranski, Clinic of Hematology, Pleven, Bulgaria; 6Department of Internal Medicine, Hematology and Oncology, Masaryk University Hospital, Brno, Czech Republic; 7Charles University Hospital, Prague, Czech Republic; 8Faculty of Medicine Hradec Kralove, Charles University, Prague, Czech Republic; 9Department of Haemato-Oncology, University Hospital Ostrava and Faculty of Medicine University of Ostrava, Ostrava, Czech Republic; 10Barts Health NHS Trust, The Royal London Hospital, London, United Kingdom; 11Principia Biopharma Inc, South San Francisco, CA, USA; and 12Department of Medicine, Hammersmith Hospital, London, United Kingdom Disclosures: David J. Kuter . Employment: Massachusetts General Hospital . Consultancy: Actelion (Syntimmune), Agios, Alnylam, Amgen, Argenx, Bristol Myers Squibb (BMS), Caremark, Daiichi Sankyo, Dova, Kyowa-Kirin, Merck Sharp Dohme, Momenta, Novartis, Pfizer, Platelet Disorder Support Association, Principia, Protalex, Protalix, Rigel, Sanofi, Genzyme, Shionogi, Shire, Takeda (Bioverativ), UCB, Up-To-Date, Zafgen . Research funding: Actelion (Syntimmune), Agios, Alnylam, Amgen, Argenx, Bristol Myers Squibb (BMS), Kezar, Principia, Protalex, Rigel, Takeda (Bioverativ) . Honoraria: Actelion (Syntimmune), Agios, Alnylam, Amgen, Argenx, Bristol Myers Squibb (BMS), Caremark, Daiichi Sankyo, Dova, Kyowa-Kirin, Merck Sharp Dohme, Momenta, Novartis, Pfizer, Platelet Disorder Support Association, Principia, Protalex, Protalix, Rigel, Sanofi, Genzyme, Shionogi, Shire, Takeda (Bioverativ), UCB, Up-To-Date, Zafgen . Patents and royalties: Up-to-Date 2 Bruton Tyrosine Kinase (BTK) Inhibition Targets Both Adaptive and Innate Drivers of Immune-Mediated Disease1,2 B cells, Monocyte, Mast cells, T cells Neutrophils plasma cells macrophage basophils Blocks B-cell receptor Blocks IgG-mediated FcγR Blocks IgE-mediated FcεR Inhibits activation, Inhibits plasma cell activation, phagocytosis, activation and adhesion, recruitment, No effect differentiation and antibody inflammatory mediators degranulation oxidative burst production BTK inhibition BTK BTK BTK BTK BTK BTK Adaptive Innate FcγR, Fcγ receptor; FcεR, Fcε receptor; Ig, immunoglobulin. 3 1. López-Herrera G, et al. J Leukoc Biol. 2014;95:243-250. 2. Langrish C, et al. JID (ESDR). 2019;139:S216 (abstract 011). Rilzabrutinib (PRN1008) is Specifically Designed for Immune-Mediated Diseases BTK Desired Inhibition Range RLK TEC BMX BLK Durable Occupancy With Selectivity Reversibility Low Exposure Precise Inhibition Safety Efficacy 4 BLK, B lymphoid tyrosine kinase; BMX, bone marrow kinase on chromosome X; BTK, Bruton tyrosine kinase; RLK, resting lymphocyte kinase; TEC, Tec protein tyrosine kinase. Rilzabrutinib Does Not Impact Platelet Aggregation Ibrutinib has significant effects Rilzabrutinib does not alter platelet aggregation in on platelet aggregation in HV blood taken from healthy volunteers or ITP patients 1 µM Ibrutinib − 1 µM Rilzabrutinib − 1 µM Rilzabrutinib − Healthy Volunteers Healthy Volunteers ITP Patients Platelet-Rich Plasma (PRP) was adjusted to 200,000-300,000 in healthy volunteers. Platelet count >125,000 in ITP patients was required for inclusion in the study. 5 Langrish C, et al. Blood (ASH). 2017;130:suppl 1 (abstract 1052). Adaptive, Open-Label, Dose-Finding, Phase I/II Study of Oral Rilzabrutinib in Relapsed/Refractory ITP Key inclusion criteria Rilzabrutinib intrapatient dose escalation . Adults age 18-80 y with relapsed/refractory ITP Doses* (24 wk): 200 and 400 mg qd, 300 and 400 mg bid . Primary or secondary to other diseases (eg, SLE, CLL) Oral treatment Higher Dose . No other available/approved treatment options . 3+3 design No response; . ≥ 2 platelet counts < 30,000/μL at study entry escalate to higher dose . Adequate hematologic, hepatic, and renal function Initial Rilzabrutinib Continue at . Stable concomitant CS or TPO-RA was allowed Dose Response Initial Dose Primary Endpoint Two or more consecutive platelet counts ≥ 50,000/μL without requiring rescue medication Additional endpoints . Any 2 platelet counts ≥ 50,000/µL . Stable response (platelet counts ≥ 50,000/μL at ≥ 50% visits for . Platelet responses over time, by duration of treatment, and clinical 4 of 8 last weeks of active treatment) benefit (≥ 30,000/μL) . Safety NCT03395210; EudraCT 2017-004012-19. bid, twice daily; CLL, chronic lymphocytic leukemia; qd, once daily; SLE, systemic lupus erythematosus. 6 *Dose escalation part of the study was completed with all patients currently treated with the 400 mg bid dose. ITP Patient Characteristics Were Similar Across All Treatment Groups In a Difficult-to-Treat Population All Patients 400 mg bid (N = 47) (n = 32) Median age, y (range) 50 (21-74) 50 (21-74) . Patients were heavily pretreated Female, n (%) 27 (57) 20 (63) − Median of 6 prior therapies − ITP classification, n (%) Median duration of ITP of 7+ years − 28% had undergone prior Primary ITP 44 (94) 31 (97) splenectomy Secondary ITP 3 (6) 1 (3) Median duration of ITP, y (range) 7.8 (0.4-52.5) 7.3 (0.4-52.5) . 31 (66%) patients were on ≥ 1 concomitant ITP medication Median baseline platelet count, 14 (3-33) 13 (4-33) (CS and/or TPO) and were considered x109/L (range) inadequate responders Median number of prior 6 (1-54) 6 (1-54) ITP therapies (range) Splenectomy, n (%) 13 (28) 9 (28) At least one prior ITP therapy 100% 100% 7 Data cut-off 22Apr2020. Oral Rilzabrutinib Achieved Primary Endpoint in 50% Patients Treated > 12 weeks and Responses were Maintained Over Time Patients Achieving Platelet Counts ≥ 50 × 109/L (80% CI) Primary Endpoint* Treatment Duration and Dose 2 consecutive 50% of Counts 4 of Final 6 All patients enrolled (N = 47) 43% (34, 52) 34% (26, 43) 28% (20, 37) ≥ 12 wk treatment (n = 36) 50% (40, 60) 39% (29, 50) 33% (24, 44) Includes patients escalated to 400 mg bid Initiated 400 mg bid (n = 32) 44% (33, 55) 38% (27, 49) 31% (22, 42) ≥ 12 wk treatment (initial 400 mg bid) 50% (38, 62) 42% (31, 55) 35% (24, 47) (n = 26) . Rilzabrutinib treatment for ≥ 12 weeks further improved platelet responses Data as of 05May2020. 8 *Primary endpoint was defined as 2 consecutive platelet counts ≥ 50,000/μL without requiring rescue medication. Platelet Responses Had a Fast Onset and Were Maintained in the Majority of Patients Who Started on Rilzabrutinib 400 mg bid Dose Starting Dose 400 mg bid (n = 32) Fast onset . By day 8: platelets ≥ 30×109/L* − 53% of patients initiating 400 mg bid − 79% of primary endpoint responders . By week 4: 57% of responders achieved the primary endpoint† Responses were maintained . Responders maintained platelet counts − 71% of time (weeks) at ≥ 50×109/L − 88% of time (weeks) at ≥ 20×109/L above baseline Responded within 4 weeks (orange) Data cut-off 22Apr2020. Responders (colored dots/lines) *Day 8 is the first platelet count taken after the start of treatment. 9 †Primary endpoint was defined as 2 consecutive platelet counts ≥ 50,000/μL without requiring rescue medication. Non-responders (gray) Rilzabrutinib at All Doses and Treatment Times Achieved Significant, Consistent Responses Across Subgroups Primary Response (N = 47) 43% . Overall, 43% of patients met the primary endpoint*, Completed ≥12 Wk Rilzabrutinib (n = 36) 50% which increased with ≥12 weeks of rilzabrutinib Baseline Platelets ≤15K . Rilzabrutinib showed 15/38 (40%) heavily pretreated 40% (n = 25) patients responding (≥ 4 prior therapies) Heavily Pretreated . 40% Similar responses were achieved in patients receiving (≥4 Prior Therapies) (n = 38) rilzabrutinib monotherapy (n=7/16) and inadequate responders on concomitant therapy (n=13/31) Rilzabrutinib Monotherapy (n = 16) 44% Rilzabrutinib + Concomitant Therapy (n = 31) 42% 0% 25% 50% 75% 100% Platelet Response Data cut-off 22Apr2020. 10 *Primary endpoint was defined as 2 consecutive platelet counts ≥ 50,000/μL without requiring rescue medication. Rilzabrutinib Was Well-Tolerated in ITP Patients . Median treatment duration (range) − All patients: 17.7 wk (0.6-41.9) All Patients 400 mg bid (N = 47) (n = 32) − 400 mg bid: 18.0 wk (1.4-24.6) Related TEAEs (≥ 10%), n (%) Grade 1 Grade 2 Grade 1 Grade 2 . Related TEAEs were reported in 21 patients (45%); all were transient and grade 1 or 2 All related TEAEs 10 (21) 11 (23) 15 (47) 11 (34) − No related SAEs Diarrhea 14 (30) 2 (4) 11 (34) 2 (6) . No treatment-related bleeding or thrombotic events Nausea 12 (26) 1 (2) 8 (25) 1 (3) . No significant changes in the ITP-BAT Fatigue 5 (11) 1 (2) 3 (9) 1 (3) bleeding scale from baseline to last visit . Safety profile is consistent with safety observed to date in pemphigus1 Data cut-off 22Apr2020. TEAEs, treatment-emergent adverse events. 11 1. Murrell D, et al. AAD. 2018:LBA 10086. Conclusions . 50% of patients achieved the primary endpoint response when initiated on rilzabrutinib 400