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

* Histologically confirmed diagnosis of a solid tumor malignancy harboring AKT1 E17K mutation identified through molecular testing (NGS- or PCR-based) with a Clinical Laboratory Improvement Amendments-certified (or equivalent) diagnostic test.

* Unresectable or metastatic disease

* Progressed on, intolerant to, or declined prior standard-of-care therapy (including targeted 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.

* 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