ORIC Pharmaceuticals, Inc. announced initial data from the ongoing ORIC-533 Phase 1 dose escalation trial in patients with relapsed/refractory multiple myeloma at the 65thAmerican Society of Hematology (ASH) Annual Meeting. ORIC-533 is being evaluated in a Phase 1 dose escalation trial in patients with relapsed/refractory multiple myeloma. The primary objectives of the trial are safety and determination of the recommended Phase 2 dose (RP2D).

Additional objectives include characterization of the pharmacokinetics, pharmacodynamics, and preliminary antitumor activity. As of November 28, 2023, a total of 23 patients with multiple myeloma received doses ranging from 400 mg to 2400 mg once daily. The study included a heavily pretreated patient population where 100% of patients were triple-class refractory, 91% were penta-refractory, and 57% also received prior anti-BCMA bispecific antibody and/or CAR-T therapy.

ORIC-533 demonstrated a favorable pharmacokinetic profile with an estimated plasma half-life of ~24 hours, which supports QD dosing. ORIC-533 clinical exposures achieved concentrations associated with efficacy in ex vivo models. ORIC-533 also demonstrated strong inhibition of soluble CD73 enzymatic activity across all dose levels, highlighting good target engagement, including in the bone marrow.

ORIC-533 was well tolerated with only Grade 1 and 2 treatment-related adverse events (TRAEs), without any specific recurrent toxicity. There were no dose limiting toxicities, dose reductions or treatment-related serious adverse events. ORIC-533 exhibited clear evidence of immune activation in the majority of patients dosed at = 1200 mg, as evidenced by an increased abundance and fraction of activated CD8+ T cells and NK cells.

At the 1600 mg dose, there were notable reductions in soluble BCMA levels in serum, indicating that ORIC-533 was having a measurable antimyeloma effect. Soluble BCMA levels have been reported to correlate with clinical response on treatment and predict progression free survival of various therapies. Finally, there were multiple examples of clinical activity, including a confirmed minor response in a patient with penta-refractory myeloma who had progressed on an anti-BCMA bispecific antibody 3 months before study entry.

Next Steps: The company intends to complete dose escalation for ORIC-533 in the first quarter of 2024. Given the overall profile of ORIC-533, it is an ideal candidate for development in combination with other immune-based antimyeloma therapies, and the company intends to evaluate strategic partnerships to enable such development.