A phase IIA clinical trial to evaluate a reversible Bruton’s tyrosine kinase inhibitor (BTKi) HBW-3220 capsules in patients with relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma (B-NHL).

e19042 Background: This clinical study is to evaluate HBW-3220, a novel BTKi with an improved in vitro profile than the existing non-covalent drugs pirtobrutinib (approved) and nemtabrutinib (Phase III). HBW-3220 shows superior inhibition against BTK wild-type and several common mutants, such as C481S, C481R, T474I, T316A, and L528W (enriched in pirtobrutinib resistance), and hematopoietic cell kinase (HCK, a key contributor to BTKi resistance due to kinase-defective BTK). Methods: This phase IIA clinical study is conducted in R/R B-NHL patients who had received two or more prior lines of treatment. The dose escalation study adopts accelerated titration and a "3+3" design, with a daily single dose of 15, 30, 60, 90, 120, or 150 mg. During the dose escalation phase, the sponsor and investigators determine whether to expand the cohort of the previous dose based on the existing data. Adverse events (AEs) are assigned according to NCI Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Response assessment is based on iwCLL 2018 guidelines for chronic lymphocytic leukemia (CLL), IWWM-7 consensus for Waldenstrom macroglobulinemia (WM), and Lugano 2014 guidelines for all other lymphomas, including small lymphocytic lymphoma (SLL), diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), and follicular lymphoma (FL). Results: 29 patients have been enrolled, and the dose escalation study has been completed. No dose-limiting toxicity (DLT) occurred in any patient, implicating good tolerability. Adverse events (AEs), similar to other BTKis, were mostly Grade 1 or 2, including fever (36%), diarrhea (32%), headache (18%), anemia (39%), infectious pneumonia (18%), decreased neutrophils count (39%), decreased platelet count (29%), increased alanine aminotransferase (21%), etc. Drug-related Grade 3 AEs included decreased neutrophil count (n=3, 11%), increased lymphocyte count (n=2, 7%), and infectious pneumonia (n=2, 7%). 23 patients underwent at least 1 response assessment. The overall response rate (ORR) in CLL/SLL (all with prior irreversible BTKi treatment, and 4 of them with additional BCL2 inhibitor treatment), MZL, MCL, and DLBCL patients were 83% (5/6), 50% (2/4), 40% (2/5) and 33% (1/3), respectively. Among the ORR, 90% (9/10) were in the 90 mg and above dose group, regardless of previous BTKi treatment history or mutation status of p53 and BTK. After oral administration, the drug exposures showed dose-dependent increases. The time to maximum plasma concentration (Tmax) was 2 hours, and the elimination half-life (T1/2) was 19 hours. Conclusions: The current data show that HBW-3220 is well tolerated with no DLT occurred at daily doses up to 150 mg, displaying most promising efficacy in patients with CLL/SLL, MZL, and MCL. Clinical trial information: ChiCTR2200062537.