Paulus, Aneel

Abstract Purpose: Development of B-cell lymphoma 2 (BCL-2)–specific inhibitors poses unique challenges in drug design because of BCL-2 homology domain 3 (BH3) shared homology between BCL-2 family members and the shallow surface of their protein–protein interactions. We report herein discovery and extensive preclinical investigation of lisaftoclax (APG-2575). Experimental Design: Computational modeling was used to design “lead” compounds. Biochemical binding, mitochondrial BH3 profiling, and cell-based viability or apoptosis assays were used to determine the selectivity and potency of BCL-2 inhibitor lisaftoclax. The antitumor effects of lisaftoclax were also evaluated in several xenograft models. Results: Lisaftoclax selectively binds BCL-2 (Ki < 0.1 nmol/L), disrupts BCL-2:BIM complexes, and compromises mitochondrial outer membrane potential, culminating in BAX/BAK-dependent, caspase-mediated apoptosis. Lisaftoclax exerted strong antitumor activity in hematologic cancer cell lines and tumor cells from patients with chronic lymphocytic leukemia, multiple myeloma, or Waldenström macroglobulinemia. After lisaftoclax treatment, prodeath proteins BCL-2‒like protein 11 (BIM) and Noxa increased, and BIM translocated from cytosol to mitochondria. Consistent with these apoptotic activities, lisaftoclax entered malignant cells rapidly, reached plateau in 2 hours, and significantly downregulated mitochondrial respiratory function and ATP production. Furthermore, lisaftoclax inhibited tumor growth in xenograft models, correlating with caspase activation, poly (ADP-ribose) polymerase 1 cleavage, and pharmacokinetics of the compound. Lisaftoclax combined with rituximab or bendamustine/rituximab enhanced antitumor activity in vivo. Conclusions: These findings demonstrate that lisaftoclax is a novel, orally bioavailable BH3 mimetic BCL-2–selective inhibitor with considerable potential for the treatment of certain hematologic malignancies.

Despite considerable advances in the treatment of multiple myeloma over the past decade, progression of disease is inevitable, and patients ultimately succumb to relapsed and refractory disease. Efficacious therapeutic regimens that target the key biological pathways that are essential for malignant plasma cell survival are necessary in the efforts to improve patient survival outcomes. The Bcl-2 family of proteins comprise oncogenes that promote myeloma cell survival by conferring resistance to apoptosis. These proteins are frequently upregulated in myeloma cells, thus making them attractive therapeutic targets. Several small molecule inhibitors of Bcl-2-family proteins are currently in clinical development for the treatment of relapsed/refractory multiple myeloma. Venetoclax, a Bcl-2-specific inhibitor, has generated the most clinical data and has shown promising results in patients with multiple myeloma harboring the t (11;14) translocation. Venetoclax has shown efficacy when combined with anti-CD38 monoclonal antibodies, immunomodulatory drugs, and proteasome inhibitors. Several other Bcl-2 inhibitors are in clinical development, as are inhibitors of Mcl-1, a Bcl-2-family oncoprotein that is perhaps more critical for myeloma cell survival than Bcl-2. This review will summarize the latest clinical data regarding the clinical development of Bcl-2-family protein inhibitors in the treatment of relapsed/refractory multiple myeloma.

Abstract Therapeutic strategies that target novel pathways are urgently needed for patients with relapsed/refractory multiple myeloma (RRMM). Ibrutinib is an oral covalent inhibitor of Bruton tyrosine kinase, which is overexpressed in MM cells. This phase 1 dose‐escalation study examined various doses of ibrutinib in combination with standard doses of lenalidomide (25 mg) and dexamethasone (40 mg) using a standard 3 + 3 design in RRMM patients. The primary objective was to determine the maximum tolerated dose (MTD) of ibrutinib in combination with lenalidomide and dexamethasone. Patients ( n = 15) had received a median of 4 prior regimens, 53% were triple‐class exposed, 33% were penta‐exposed, and 54% were lenalidomide‐refractory. The MTD of ibrutinib was 840 mg ( n = 6) and only 1 dose‐limiting toxicity; a grade 3 rash possibly related to ibrutinib was noted. The most common ≥ grade 3 adverse events were rash in 2 (13%), lymphopenia in 2 (13%), leukopenia, neutropenia, thrombocytopenia, and anemia all occurring in 3 (20%) patients each. One patient achieved a partial response for an overall response rate of 7%. The clinical benefit rate was 80%. The median time to progression was 3.8 months. Ibrutinib, lenalidomide and dexamethasone appears to be a safe and well‐tolerated regimen with reasonable efficacy in heavily pretreated RRMM patients.

Abstract Background: Concern exists that the clinical trial populations differ from respective cancer populations in terms of their age distribution affecting the generalizability of the results, especially the underrepresented minorities. We hypothesized that the clinical trials that do not report race are likely to suffer from a higher degree of age disparity as well and the issue should be addressed in conjunction with each other. Methods: Food and Drug Administration (FDA) drug approvals from 7/2007-6/2019 were reviewed to identify oncology approvals, and trials with age details were selected. The primary outcome was the weighted mean difference in age between the clinical trial population and realworld population for various cancers. The secondary outcomes were the prevalence of race reporting and association of age and race reporting with each other. Group comparisons for proportions were performed using the χ2 test while continuous variables were compared using multiple analysis of variance (MANOVA) test or students t-test as appropriate. P values < .05 were considered significant. Results: Of the 261 trials, the race was reported in 223 (85.4%) of the trials while 38 trials (14.6%) had no mention of race. Race reporting improved minimally over time – 29 (85.3%) in 2007-2010 vs. 49 (80.3%) in 2011-2014 vs. 145 (85.4%) during 2015-2019 (p-value=0.41). No significant association between type of cancer and race reporting was noted – 147 (86.5%) of solid cancer trials vs. 76 (83.5%) of hematological cancer trials reported race (p-value=0.52). Age discrepancy between the clinical trial population and the real-world population was present for several cancer types. The discrepancy was higher for studies that did not report race, mean difference - 8.8 years 4 (95% CI -12.6 to -5.0 years) vs. studies that did report the race, mean difference -5.1 years, (95% CI -6.4 to -3.7 years), p-value=0.04. Conclusion: The study demonstrates that a significant number of clinical trials leading to cancer drug approvals suffer from racial and age disparity when compared to real-world populations and that the two factors may be interrelated. We recommend continued efforts to recruit diverse populations. In the meantime, reporting these characteristics for these crucial trials should be mandated. Citation Format: Thejus Jayakrishnan, Sonikpreet Aulakh, Mizba Baksh, Kianna Nguyen, Meghna Ailawadhi, Ayesha Samreen, Ricardo Parrondo, Taimur Sher, Vivek Roy, Rami Manochakian, Aneel Paulus, Asher Chanan-Khan, Sikander Ailawadhi. Disparity in race and age reporting in landmark cancer clinical trials: Underrepresentation of the traditionally underserved U.S. population [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-104.

Background: Concern exists that the clinical trial populations differ from respective cancer populations in terms of their age distribution affecting the generalizability of the results, especially in underrepresented minorities. We hypothesized that the clinical trials that do not report race are likely to suffer from a higher degree of age disparity. Methods: Food and Drug Administration (FDA) drug approvals from July 2007 to June 2019 were reviewed to identify oncology approvals, and trials with age details were selected. The outcomes studied were the weighted mean difference in age between the clinical trial population and real-world population for various cancers, the prevalence of race reporting and association of age and race reporting with each other. Results: Of the 261 trials, race was reported in 223 (85.4%) of the trials, while 38 trials (14.6%) had no mention of race. Race reporting improved minimally over time: 29 (85.3%) in 2007–2010 vs. 49 (80.3%) in 2011–2014 vs. 145 (85.4%) during the period 2015–2019 (p-value = 0.41). Age discrepancy between the clinical trial population and the real-world population was higher for studies that did not report race (mean difference −8.8 years (95% CI −12.6 to −5.0 years)) vs. studies that did report it (mean difference −5.1 years, (95% CI −6.4 to −3.7 years), p-value = 0.04). Conclusion: The study demonstrates that a significant number of clinical trials leading to cancer drug approvals suffer from racial and age disparity when compared to real-world populations, and that the two factors may be interrelated. We recommend continued efforts to recruit diverse populations.