Open-Label Study of BBO-10203 in Subjects With Advanced Solid Tumors

Inclusion Criteria: * Locally advanced and unresectable or metastatic HER2-positive advanced breast cancer (aBC), HR-positive/HER2-negative advanced breast cancer, KRAS mutant advanced colorectal cancer (aCRC), or KRAS mutant advanced non-small cell lung cancer (aNSCLC) * Measurable disease by RECIST v1.1 (except for HR-positive HER2-negative aBC where evaluable bone-only disease is permitted) * Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-1 * Adequate LVEF assessed by ECHO or MUGA (BBO-10203 + Trastuzumab cohorts only) * Stable brain metastases * Patients with HER2-positive aBC: Must have had at least 2 prior lines of anti-HER2-directed therapy. Only 1 prior line is acceptable where there is no other regionally available standard of care (SoC) * Monotherapy Cohort patients with HR-positive, HER2-negative aBC, KRAS mutant aCRC or aNSCLC: Must have progression on, or disease recurrence after at least one line of SOC treatment or in the opinion of the investigator, would be unlikely to tolerate or derive clinically meaningful benefit from SoC therapy * BBO-10203 + Fulvestrant combination cohort patients with HR-positive, HER2-negative aBC: confirmed PIK3CA mutation, must have been treated with a CDK4/6i * BBO-10203 + Fulvestrant + ribociclib combination cohort patients with HR-positive, HER2-negative aBC: confirmed PIK3CA mutation, no prior systemic therapy in the aBC setting permitted * BBO-10203 + FOLFOX + Bevacizumab combination cohort patients with K…