A Phase 1/1b Study of IAM1363 in HER2 Cancers

Key Inclusion Criteria:

* Age ≥ 18 years
* Have relapsed/refractory HER2-altered malignancy; for selected cohorts, prospective confirmation of HER2 alteration by central testing is required
* Have progression of disease after the last systemic therapy, or be intolerant of last systemic therapy
* Have radiographically measurable disease by RECIST v1.1 and/or RANO-BM
* Eastern Cooperative Oncology Group (ECOG) performance score 0-1
* Have adequate baseline hematologic, liver and renal function
* Have left ventricular ejection fraction (LVEF) ≥ 50%
* Able to swallow oral medication

Key Exclusion Criteria:

* Clinically significant cardiac disease
* Infection with human immunodeficiency virus (HIV)-1 or HIV-2. Exception: Participants with well-controlled HIV (e.g., CD4 \>350/mm3 and undetectable viral load) are eligible
* Current active liver disease including hepatitis A, hepatitis B , or hepatitis C
* Refractory nausea and vomiting, malabsorption, external biliary shunt, or significant small bowel resection that would preclude adequate absorption
* Uncontrolled diabetes
* History of solid organ transplantation
* History of Grade ≥2 CNS hemorrhage, or any CNS hemorrhage within 28 days before C1D1
* Prior history of non-infectious interstitial lung disease (ILD). (Exceptions: participants with prior grade 1 ILD that has completely resolved are eligible)
* Participants requiring immediate local therapy for brain metastases