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, prospectiveconfirmation of HER2 alteration by central testing is required

• Have progression of disease after the last systemic therapy, or be intolerant oflast 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 viralload) are eligible

• Current active liver disease including hepatitis A, hepatitis B , or hepatitis C

• Refractory nausea and vomiting, malabsorption, external biliary shunt, orsignificant 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