A Phase I/IIa Trial of HMBD-001 in Advanced HER3 Positive Solid Tumours

Participants with advanced solid tumours will receive their assigned dose level of HMBD-001 diluted in 0.9% sodium chloride, administered once a week as a 120-minute intravenous (IV) infusion. Cycles are 28 days with no break in between; administration may continue for up to 6 cycles but may continue for longer if the participant is deemed to be benefitting.

Participants with metastatic castration resistant prostate cancer (mCRPC) confirmed as HER3 positive with no PTEN loss or with a NRG1 fusion rearrangement will receive the HMBD-001 recommended Phase 2 dose (RP2D) as determined in Part A, diluted in 0.9% sodium chloride and administered once a week as a 120-minute IV infusion, in combination with enzalutamide administered at a fixed dose of 160 mg once daily, in 28-day cycles with no break between cycles. Immediately before commencing combination therapy, participants may receive one 28-day cycle of enzalutamide monotherapy to confirm that their disease does not respond to enzalutamide alone. HMBD-001 may be administered for up to 6 cycles; enzalutamide may be continued until disease progression or unacceptable toxicity.