Objective:
Phase 1a Monotherapy Dose Escalation (Part A)
Primary Objectives:
- To assess the safety of OKI-219, and to identify the maximum tolerated dose (MTD) and one or more pharmacologically active dose (PAD) levels of OKI-219 as a single agent in participants with advanced solid tumors with the PI3KαH1047R mutation
Secondary Objectives:
- To characterize additional measures of the safety and tolerability of OKI-219 in participants with advanced solid tumors with the PI3KαH1047R mutation
- To assess the plasma PK of OKI-219 following single and multiple doses as monotherapy
- To assess the effect of food on the PK of OKI-219
- To estimate the preliminary antitumor activity of OKI-219 as monotherapy
- To assess the dose-response impact of OKI-219 on PI3KαH1047R circulating tumor DNA (ctDNA) levels
- To determine the impact of OKI-219 dosing on blood glucose and insulin
- To assess the PDx activity of OKI-219 and its association with PK, safety, and efficacy
Phase 1b Combination Dose Escalation and Dose Optimization (Parts B and C)
Primary Objectives:
- Fulvestrant Combination (Part B)
Phase 1b
To assess the safety of OKI-219 when combined with fulvestrant and identify 2 PAD levels of OKI-219 + fulvestrant to evaluate in the Dose Optimization arms in participants with HR+/HER2–/PI3KαH1047Rmutated metastatic breast cancer
- Dose Optimization
To compare 2 PAD levels of OKI-219 + a fixed dose of fulvestrant and identify the recommended Phase 2 dose (RP2D) for OKI-219 combined with fulvestrant in participants with HR+/HER2–/PI3KαH1047Rmutated metastatic breast cancer
- Trastuzumab Combination (Part C)
Phase 1b
To assess the safety of OKI-219 when combined with trastuzumab and identify 2 PAD levels of OKI-219 + trastuzumab to evaluate in the Dose Optimization arms in participants with HR±/HER2+/PI3KαH1047Rmutated metastatic breast cancer
- Dose Optimization
To compare 2 PAD levels of OKI-219 + a fixed dose of trastuzumab and identify the RP2D for OKI-219 combined with trastuzumab in participants with HR±/HER2+/PI3KαH1047R-mutated
metastatic breast cancer
Secondary Objectives:
- To characterize additional measures of the safety and tolerability of OKI-219 in combination with fulvestrant or trastuzumab in participants with metastatic breast cancer with the PI3KαH1047R mutation
- To assess the plasma PK of OKI-219 following single and multiple doses in combination with fulvestrant or trastuzumab
- To estimate the preliminary antitumor activity of OKI-219 in combination with fulvestrant or trastuzumab
- To assess the dose-response impact of OKI-219 in combination with fulvestrant or trastuzumab on PI3KαH1047R ctDNA levels
- To determine the impact of OKI-219 dosing in combination with fulvestrant or trastuzumab on blood glucose and insulin
- To assess the PDx activity of OKI-219 in combination with fulvestrant or trastuzumab and its association with PK, safety, and efficacy