A Phase 1 Trial of ZN-A-1041 Enteric Capsules or Combination in Participants With Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Advanced Solid Tumors

This study is composed of three parts designed to evaluate the safety and efficacy of ZN-A-1041 in participants with HER2-positive advanced solid tumors.

Phase 1a (Monotherapy Dose Escalation): In this first phase, participants will receive ZN-A-1041 alone. The study will begin with a low dose of ZN-A-1041, which will be gradually increased in new groups of participants to find the highest dose that can be given safely. This will establish the recommended dose for further study.

Phase 1b (Combination Dose Escalation): In the second phase, the study will evaluate the safety of giving ZN-A-1041 together with established standard-of-care therapies for HER2-positive breast cancer. Participants will be enrolled into one of three combination arms to receive ZN-A-1041 with either T-DM1, T-DXd, or a pertuzumab/trastuzumab-based regimen. This phase will identify the recommended dose for these combination therapies.

Phase 1c (Combination Dose Expansion): In the final phase, additional participants will be enrolled to receive ZN-A-1041 at the recommended combination doses identified in Phase 1b. This will allow for a more thorough evaluation of the safety and preliminary efficacy of these treatment regimens.

Throughout the study, participants will undergo screening, treatment, and follow-up periods to collect comprehensive data on the safety, tolerability, pharmacokinetics, and anti-tumor activity of ZN-A-1041, both as a single agent and in combination.