A Study to Learn About Study Medicine ALTA2618 in Adults With AKT1 E17K-Mutant Solid Tumors

Inclusion Criteria:

• Histologically confirmed diagnosis of a solid tumor malignancy harboring AKT1 E17Kmutation identified through molecular testing (NGS- or PCR-based) with a ClinicalLaboratory Improvement Amendments-certified (or equivalent) diagnostic test.

• Unresectable or metastatic disease

• Progressed on, intolerant to, or declined prior standard-of-care therapy (includingtargeted therapy, if applicable) appropriate to tumor type and stage

• Evaluable or measurable disease per RECIST v1.1

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

• Adequate organ function.

Exclusion Criteria:

• Prior treatment with PI3K and/or mTOR inhibitors

• Patients known to have KRAS, NRAS, HRAS, or BRAF genomic alterations in their tumor

• Known condition that prohibits ability to swallow or absorb an oral medication

Other inclusion/exclusion criteria may apply.