Search

Acalabrutinib, a next-generation Bruton’s tyrosine kinase inhibitor (BTKi), associates with dramatic efficacy against B-cell malignancies. Recently, unexplained ventricular arrhythmias (VAs) with next-generation BTKi-therapy have been reported. Yet, whether acalabrutinib associates with VAs in long-term follow-up is unknown. Leveraging a large-cohort of 290 consecutive B-cell malignancy patients treated with acalabrutinib from 2014 to 2020, we assessed the incidence of VAs. The primary-endpoint was incident VA development (ventricular fibrillation, ventricular tachycardia, and symptomatic premature ventricular contractions). Probability-scores were assessed to determine likelihood of acalabrutinib-association. Incident rates as function of time-on-therapy were calculated. Weighted average observed incidence rates were compared with expected population rates using relative-risks. Absolute excess risk (AER) for acalabrutinib-associated VAs was estimated. Over 1063 person-years of follow-up, there were 8 cases of incident-VAs, including 6 in those without coronary disease (CAD) or heart failure (HF) and 1 sudden-death; median time-to-event 14.9 months. Among those without prior ibrutinib-use, CAD, or HF, the weighted average incidence was 394 per 100 000 person years compared with a reported incidence of 48.1 among similar-aged non–BTKi-treated subjects (relative risk, 8.2; P

BACKGROUND: B-Chronic Lymphocytic Leukemia (CLL) is still uncurable but very powerful new tools are available with the use of chemoimmunotherapy (CIT). Purine nucleoside-based regimens that incorporate rituximab have generated very high levels of overall responses (OR) with significant percentage of those complete responses (CR) in previously untreated CLL. Here we report and update our experience with a phase 2 pentostatin-based CIT regimen for previously untreated CLL as conducted at 2 medical centers. We also studied the association of outcome based on risk stratification parameters and achievement of minimal residual disease. METHODS: Building on prior work of pentostatin in CLL by us (Kay ASH, 2004) and others, we initiated a trial of combined pentostatin (P)(2 mg/m2), cyclophosphamide (C)(600 mg/m2) and rituximab (R)(375 mg/m2) for symptomatic, previously untreated patients (n=65). This PCR regimen is given on a 21-day, 6-cycle schedule. However, the initial cycle of treatment uses thrice weekly rituximab as described by us earlier. In brief, this was rituximab at 100 mg/m2 on day 1, 375 mg/m2 on days 3 and 5 of the first week only. Prophylactic Sulfamethoxazole/Trimethoprim and Acyclovir were given to all patients for 1 year starting on the first cycle of therapy with PCR. All patients were risk stratified using CD38, ZAP-70, immunoglobulin heavy chain variable region gene (IgVH) and FISH panel assessments at entry. RESULTS: These patients were characterized as mostly in high-risk categories. Of 64 evaluable patients, 34 (53%) were high Rai risk (stage 3–4), 71% were non mutated for the IgVH gene, 34% were CD38+ and 34% were ZAP-70+. Thirty patients (52%) had one FISH anomaly, and 21 (36%) had complex FISH defects. Thirty-eight patients (58%) had grade 3+ hematologic toxicity but minimal transfusion needs, and no major infections. NCI Working Group Criteria Responses occurred in 58 (91%) with 26 (41%) complete responses (CR), 14 (22%) nodular partial responses (nodular PR), and 18 (28%) partial responses (PR) patients. Outcome for all 64 patients demonstrates a median progression-free survival of 32.6 months. Importantly, no high risk factor (i.e., age, FISH, IgVH status, CD38+, ZAP-70+) except for del (17p) defect (n=3) precluded attaining a CR or NPR. In contrast, we found this regimen was equally effective in young vs. elderly (>70 yrs) patients and in del(11)(q22.3) vs. other favorable prognostic FISH factors. Examination of outcome among CR and nodular PR patients for PFS by flow cytometry status (negative vs. positive, i.e., ≤ 1 % CD5+/CD19+ vs. ≥ 1 % CD5+/CD19+) demonstrated improvement in progression free survival for patients who attained flow cytometry negativity (p = 0.009). Conclusion: This novel regimen of pentostatin, cyclophosphamide and rituximab for previously untreated CLL demonstrated significant clinical activity despite poor risk-based prognoses with minimal toxicity in terms of bone marrow suppression and/or infections. The additional feature of this approach is the ability to have durable responses for all age groups and even CLL patients with a del(11)(q22.3).

Chronic lymphocytic leukemia (CLL) is an incurable adult leukemia characterized by disrupted apoptosis. While the majority of patients with CLL are asymptomatic at diagnosis, most progress and require therapy. Identification of new targets and therapeutic agents is therefore a high priority for the treatment of CLL. Synthetic chemistry yielded derivatives of the COX-2 inhibitor, celecoxib, with increased ability to induce apoptosis in the 1–10 μ M range in prostate cancer cells, a similar proposed mechanism of action, and increased in vivo activity in a murine prostate cancer xenograft model. Based upon these data, a Rapid Access to Intervention Development (RAID) proposal is underway to generate OSU03012 for clinical studies in prostate cancer. In addition, we are examining the biologic effects of these new agents in primary CLL cells and lymphoblastic cell lines, showing a novel mechanism of cell killing independent of caspase activation and bcl-2 over-expression. To determine the in vitro activity against CLL cells, 11 CLL patient PBMCs were incubated in various concentrations of OSU03012. The LC50 at 24 hrs was 7.12μM and decreased to 5.45μM at 72 hrs. We show both early (annexin-V positive) and late (both annexin-V/PI positive) apoptosis concurrent with loss of mitochondrial membrane potential typical of apoptosis. These data suggest OSU03012 is highly cytotoxic toward CLL cells in vitro at doses well below those attainable without toxicity in a murine model. Additionally, we show that OSU03012 mediates apoptosis by activation of the intrinsic, mitochondrial pathway of apoptosis but also activates alternative caspase independent cell death pathways. CLL cells from 8 patients were incubated in 10μM OSU03012 for 24 hrs and assessed for caspase-3 and PARP. Immunoblots reveal a dose dependent increase in active caspase-3 concurrent with a decrease in the pro-form. This occurred concurrently with the appearance of the 85 kD cleaved product of PARP that is a known downstream target of caspase-3. In the same 8 patient lysates we saw no change in the inactive pro-form of caspase-8, but consistent processing of caspase-9. These data suggest that OSU03012 in part utilizes the intrinsic pathway of apoptosis to promote CLL cell death. Incubation of CLL cells with z-VAD-fmk and OSU03012 did not abrogate cell death, but eliminated processing of caspase-9, caspase-3 and PARP, suggesting that this agent also activates caspase independent mechanisms of cell death. Given the caspase dependent and independent pathways utilized by OSU03012, we assessed the dependence of cell death on bcl-2 expression. Here we show that bcl-2 over-expression in the 697 lymphoblastic cell line greatly diminishes the apoptosis observed with fludarabine, but potent apoptosis is equally observed with OSU03012 compared to the empty vector cell line. Furthermore, in the bcl-2 over-expressing cell line, caspase-3 and PARP cleavage was not observed despite equivalent apoptosis supporting further multiple mechanisms of cell killing induced by OSU03012. In summary, OSU03012 is an oral bioavailable therapeutic agent that has potent in vitro activity against primary CLL cells. This cytotoxicity is mediated by both caspase dependent and independent pathways and can overcome bcl-2 over-expression. These data provide support for further investigation of the mechanism of action of OSU03012 in CLL cells and performance of early Phase I studies in CLL as part of the RAID process.