Phase 1 Dose-Finding Study Investigating CA-4948, an IRAK4 Kinase Inhibitor, in Patients with R/R NHL: Report of Initial Efficacy and Updated Safety Information

Introduction and Purpose

IRAK4 kinase activity is essential for signaling downstream of toll-like receptors (TLR) and the interleukin-1 receptor (IL-1R) family in a variety of myeloid and lymphoid cell types. Dysregulated signaling in these pathways is frequently observed in NHL, particularly in ABC-subtype of Diffuse Large B-Cell Lymphoma (DLBCL) and Waldenström macroglobulinemia (WM). A phase 1 trial in patients with NHL is being conducted to determine safety, pharmacokinetics, and preliminary efficacy of CA-4948 as monotherapy.

Patients and Methods

At the 18-Jul-2019 data cut-off date, 22 patients have been treated with single-agent CA-4948. Five dose-escalation cohorts from 50 mg QD to 200 mg BID have been tested and cleared; a cohort of patients treated at 400 mg BID dose is currently being evaluated. Patients were diagnosed with relapsed or refractory NHL, including DLBCL (n=13), FL (n=5), HGBL with MYC and BCL2 and/or BCL6 rearrangement (n=1), WM (n=1), LPL (n=1) and MCL (n=1), had a performance status of 0 or 1 (ECOG) at baseline, and were treated in 21-day cycles until progression of disease or unacceptable toxicity, lost to follow-up or death. 5 patients had prior autologous bone marrow transplants.

Results

CA-4948 has been generally well tolerated. Grade 3/4 treatment-related adverse events included amylase/lipase increased, diarrhea, neutrophil count decreased, rash, rhabdomyolysis. Pharmacokinetics has shown favorable characteristics with dose-proportional increases in exposure. Five patients have been on treatment through the end of Cycle 4, including one patient in Cycle 10 on study for over 7 months. Five patients experienced overall tumor burden decreases of ≥20% from baseline, including at least 2 of 4 patients treated at 200 mg BID. Downstream pharmacodynamic markers of IRAK4 activity are being evaluated. Molecular characteristics including cell-of-origin will be presented.

Conclusion

CA-4948 demonstrates preliminary clinical activity. Enrollment is on-going and the MTD has not been reached. These encouraging results warrant further clinical testing in patients with advanced hematological malignancies. Clinical trial: NCT03328078.