Yannakou, Costas K.

Introduction MM is characterized by the proliferation of abnormal clonal plasma cells, causing destructive bone lesions, kidney injury, anemia, and hypercalcemia. Treatment of MM involves immunomodulatory agents, proteasome inhibitors, and anti-CD38 monoclonal antibodies to achieve disease remission. AL amyloidosis comprises disorders of abnormal extracellular deposition of misfolded proteins in various organs with resultant damage, and the key strategy of treatment is to prolong the time to or reverse organ dysfunction. However, many patients will relapse from the standard triplet or quadruplet therapies, necessitating additional treatments with novel mechanisms of action. Lisaftoclax is a novel investigational BCL-2 inhibitor with strong antitumor activity in hematologic malignancies. Here, we report clinical trial data on lisaftoclax combined with novel therapeutic regimens in pts with R/R MM or R/R AL amyloidosis. Methods Eligible patients had an ECOG performance status ≤ 2, ≥ 1 prior line of therapy, and adequate organ function. Patients with R/R AL amyloidosis had confirmed symptomatic organ involvement, purpura, and/or carpal tunnel syndrome. Lisaftoclax was administered orally daily at doses assigned in repeated 28-day cycles. Pomalidomide, daratumumab, and lenalidomide were administered per label use. Dexamethasone 40 mg (20 mg, pts > 75 years old) was administered on days 1, 8, 15, and 22 of 28-day cycles. This study evaluated the safety and efficacy of lisaftoclax combined with pomalidomide and dexamethasone (Pd; Arm A) or daratumumab, lenalidomide, and dexamethasone (DRd; Arm B) in R/R MM and lisaftoclax combined with Pd in R/R AL amyloidosis (Arm C). Intensive blood samples were collected for pharmacokinetic (PK) analyses. Results As of May 29, 2024, 52 pts were enrolled, including 42 with R/R MM and 10 with AL amyloidosis. In Arm A (n = 35), lisaftoclax was administered orally at dose assigned: 400 mg (n = 3), 600 mg (n = 4), 800 mg (n = 15), 1,000 mg (n = 7), and 1,200 mg (n = 6). In Arm B (n = 7), all pts were treated with lisaftoclax 600 mg. In Arm C (n = 10), lisaftoclax was administered at 400 mg (n = 1), 600 mg (n = 4), 800 mg (n = 3), and 1,000 mg (n = 2). The median (range) age of all patients was 69.5 (24-88) years, of whom 63.5% were male and 63.5% were ≥ 65 years of age. The enrolled patients were heavily treated, with a median (range) number of treatment cycles of 4 (1-26), and a median (range) number of prior therapy lines of 3 (1-19). In Arm A, out of 31 evaluable patients, 3 (9.7%) achieved complete remission (CR), 7 (22.6%) reached very good partial remission (VGPR), and 9 (29.0%) achieved partial response (PR). The overall response rate (ORR) was 19 (61.3%), and the ≥ VGPR rate was 10 (32.3%). In Arm B, of 4 evaluable patients, 2 (50%) achieved CR and 2 (50%) ≥ VGPR. In Arm C, of 7 assessed patients, 1 (14.3%) achieved CR, 4 (57.1%) VGPR, 1 (14.3%) PR, and 5 (71.4%) ≥ VGPR, for an ORR of 6 (85.7%); 2 pts had cardiac response. Among 49 pts in the safety population, 34 (69.4%) reported any-grade lisaftoclax treatment-related AEs (TRAEs; ≥ 5% incidence), including neutropenia (20.4%), thrombocytopenia (6.1%), leukopenia (10.2%), nausea (16.3%), abdominal distension (10.2%), diarrhea (12.2%), and constipation (8.2%). A total of 11 pts experienced grade ≥ 3 TRAEs, including neutropenia (14.3%) and febrile neutropenia (2%), and 3 pts experienced lisaftoclax-related serious AEs (1 each): febrile neutropenia, acute kidney injury, and diarrhea with electrolyte imbalance. In Arm B, 1 pt experienced a dose-limiting toxicity (prolonged QT interval). Pharmacokinetic analyses showed no drug-drug interaction (DDI) in all pts treated with lisaftoclax at all doses in combination with other therapeutic agents used in 3 arms. Conclusions Our findings suggest that lisaftoclax improves the depth of response in pts with R/R MM or AL amyloidosis when combined with Pd or DRd. These combination therapies demonstrated a favorable safety profile with no drug-drug interactions, particularly in hematologic side effects. ClinicalTrials.gov registration: NCT04942067; internal study identifier: APG2575MU101.

*Drs. Yifan Zhai and Sikander Ailawadhi are co-corresponding authors Background R/R MM is an incurable condition, with virtually inevitable relapse. AL amyloidosis is a rare disease that may cause serious illness and even death. Lisaftoclax is a novel, potent, selective BCL-2 inhibitor under clinical development for treatment of patients with hematologic malignancies or solid tumors, and has shown clinical antitumor benefits. In a previous study on chronic lymphocytic leukemia, lisaftoclax was shown to require only a short (daily vs weekly) dose ramp-up to mitigate tumor lysis syndrome and was associated with a low incidence of adverse events (AEs) (Ailawadhi et al. J Clin Oncol 2021;39:abstract 7502; Davids et al. Blood 2022;140[suppl 1]:2326-2328). Methods This multicenter study evaluated lisaftoclax combined with pomalidomide and dexamethasone (Arms A and C) or daratumumab, lenalidomide, and dexamethasone (Arm B) in patients with R/R MM (Arm A and B) or R/R amyloidosis (Arm C). Eligible patients had an ECOG performance status ≤ 2; ≥ 1 prior line of therapy; and adequate organ function. Patients with R/R amyloidosis also needed confirmed symptomatic organ involvement, in addition to purpura and/or carpal tunnel syndrome. Lisaftoclax was administered orally daily (QD) at 5 dose levels (400, 600, 800, 1,000, and 1,200 mg) without ramp-up in repeated 28-day cycles. Pomalidomide, daratumumab, and lenalidomide were administered per label use. Dexamethasone 40 mg (20 mg for patients aged > 75 years) was administered on Days 1, 8, 15, and 22 of 28-day cycles. Study objectives were safety and efficacy assessments of the combination treatments. Results As of July 3, 2023, a total of 30 patients were enrolled: 22 in Arm A at dose levels of 400 (n = 3), 600 (n = 4), 800 (n = 3), 1,000 (n = 6), and 1,200 mg (n = 6); 3 in Arm B at 600 mg; and 5 in Arm C at 400 (n = 1) and 600 mg (n = 4). A total of 66.7% of patients were male, and the median (range) age was 70.5 (24-88) years, with 66.7% of patients above the age of 65. The median (range) lines of prior therapies was 4 (1-19), and median (range) time from diagnosis to first dose was 5.2 (1-29) years. The median (range) number of treatment cycles was 4 (1-19). A total of 18 patients were triple-class-exposed, 7 had received pomalidomide, and 3 harbored t(11;14) at baseline. A total of 19 patients reported experiencing any-grade lisaftoclax treatment-related adverse events (TRAEs), including neutropenia or nausea (16.7% each); and thrombocytopenia, leukopenia, abdominal distension, constipation, or diarrhea (6.7% each). Seven patients experienced grade ≥ 3 TRAEs, including neutropenia (10%) and febrile neutropenia, iron deficiency anemia, thrombocytopenia, prolonged electrocardiogram QT interval, and acute kidney injury (3.3% each). Two patients experienced lisaftoclax-related serious AEs, of which 1 was febrile neutropenia and 1 acute kidney injury. In Arm B, 1 patient experienced a dose-limiting toxicity (prolonged QT interval). A total of 12 patients discontinued treatment because of disease progression (n = 8), an AE (n = 1), noncompliance (n = 1), and investigator/patient decision (n = 2). In Arm A, 21 patients with R/R MM were evaluable, of whom 9 experienced a partial response (PR) and 5 a very good PR (VGPR). The overall response rate (ORR [PR or better]) was 66.7%, with a median (range) time to response of 1.2 (1-3) months. After a median (range) time to response of 1.4 (1-2) months, 2 patients with R/R MM in Arm B achieved a PR (n = 1) or VGPR (n = 1). In Arm C, 3 patients with R/R amyloidosis achieved a hematologic VGPR; the ORR was 60%; the median (range) time to response was 0.9 (1-1) month; and 1 patient experienced organ function improvement. Conclusion Lisaftoclax, combined with novel therapeutic regimens, was well tolerated and has demonstrated preliminary antitumor activity in patients with AL amyloidosis or R/R MM. Internal study identifier: APG-2575-MU101; clinical trial registration: NCT04942067.

Abstract Purpose: This global phase I trial investigated the safety, efficacy, pharmacokinetics, and pharmacodynamics of lisaftoclax (APG-2575), a novel, orally active, potent selective B-cell lymphoma 2 (BCL-2) inhibitor, in patients with relapsed or refractory chronic lymphocytic leukemia or small lymphocytic lymphoma (R/R CLL/SLL) and other hematologic malignancies (HMs). Patients and Methods: Maximum tolerated dose (MTD) and recommended phase II dose were evaluated. Outcome measures were safety and tolerability (primary) and pharmacokinetic variables and antitumor effects (secondary). Pharmacodynamics in patient tumor cells were explored. Results: Among 52 patients receiving lisaftoclax, MTD was not reached. Treatment-emergent adverse events (TEAEs) included diarrhea (48.1%), fatigue (34.6%), nausea (30.8%), anemia and thrombocytopenia (28.8% each), neutropenia (26.9%), constipation (25.0%), vomiting (23.1%), headache (21.2%), peripheral edema and hypokalemia (17.3% each), and arthralgia (15.4%). Grade ≥ 3 hematologic TEAEs included neutropenia (21.2%), thrombocytopenia (13.5%), and anemia (9.6%), none resulting in treatment discontinuation. Clinical pharmacokinetic and pharmacodynamic results demonstrated that lisaftoclax had a limited plasma residence and systemic exposure and elicited rapid clearance of malignant cells. With a median treatment of 15 (range, 6–43) cycles, 14 of 22 efficacy-evaluable patients with R/R CLL/SLL experienced partial responses, for an objective response rate of 63.6% and median time to response of 2 (range, 2–8) cycles. Conclusions: Lisaftoclax was well tolerated, with no evidence of tumor lysis syndrome. Dose-limiting toxicity was not reached at the highest dose level. Lisaftoclax has a unique pharmacokinetic profile compatible with a potentially more convenient daily (vs. weekly) dose ramp-up schedule and induced rapid clinical responses in patients with CLL/SLL, warranting continued clinical investigation.

7502 Background: The BCL-2i venetoclax is active in certain HMs but can increase the risk of tumor lysis syndrome (TLS), requiring a 5-week dose ramp-up for CLL patients. Cases of severe neutropenia with venetoclax treatment have also been reported. Lisaftoclax is a novel, potent, selective BCL-2i that is active against HMs and is under clinical development. Methods: This first-in-human global phase I dose study assessed the safety, PK, PD, efficacy, and MTD/RP2D of lisaftoclax in patients with R/R CLL and other HMs. Lisaftoclax was orally administered daily in a 28-day cycle. Patients with CLL or intermediate-high TLS risk were initiated on a daily ramp-up schedule until the assigned dose before the study cycles. Results: On January 7, 2021, 35 pts had been enrolled and treated with lisaftoclax at doses ranging from 20 to 1,200 mg, with a median (range) of 2 (1-13) prior lines of treatment, and had diagnoses of R/R CLL or SLL (n = 15), MM (n = 6), FL (n = 5), WM (n = 4), and either AML, MCL, DLBCL, MDS, or HCL (n = 1 each). No DLT has been observed, even though 1,200 mg was considered as the highest dose treated. The MTD has not been reached, and no laboratory or clinical TLS has been reported. Any grade TRAEs in > 10% of pts included neutropenia (22.9%) and anemia (17.1%; hematologic), and fatigue (28.6%), diarrhea (17.1%), and nausea (11.4%; nonhematologic). Grade >3 TRAEs were neutropenia (14.3%) and thrombocytopenia, leukopenia, lymphopenia, fatigue, and nausea (2.9% of pts each). In CLL/SLL pts, grade 3-4 TRAEs included neutropenia (13.3%) and thrombocytopenia (6.7%), which did not cause treatment-related discontinuation. In all, 12 of 35 pts (34.3%) had non-treatment-related SAEs, and only two pts experienced > 1 SAE. With a median (range) treatment of 7 (3-20) cycles, 12 of 14 evaluable R/R CLL/SLL pts achieved PR, for an ORR of 85.7% and a median (range) time to response of 3 (2-7) cycles. Absolute lymphocyte counts (ALCs) were reduced at lisaftoclax doses as low as 20 mg/day. The preliminary PK profile showed that exposures increased with lisaftoclax doses from 20 to 1,200 mg (average half-life: 4-5 hours). On BH3 profiling, lisaftoclax rapidly triggered changes in BCL-2 complex in CLL/SLL pt samples, which were consistent with rapid clinical reductions in ALCs. Conclusions: Lisaftoclax was well tolerated up to 1,200 mg/day. No TLS was observed, even with the daily ramp-up schedule. There were no significant new or unmanageable safety findings, and the ORR in R/R CLL/SLL pts was 85.7%. Grade 3-4 TRAEs were infrequent, even at dose levels of 800 mg and above. BCL-2i lisaftoclax offers a treatment alternative for patients with R/R CLL/SLL and other HMs, with a daily ramp-up schedule that may be more pt “user friendly” and a favorable preliminary safety profile. Internal study identifier APG2575-001. Clinical trial information: NCT03537482.