PHARMACEUTICAL FORMULATIONS, PROCESSES, SOLID FORMS AND METHODS OF USE RELATING TO 1-ETHYL-7-(2-METHYL-6-(1H-1,2,4-TRIAZOL-3-YL)PYRIDIN-3-YL)-3,4-DIHYDROPYRAZINO[2,3-b]PYRAZIN-2(1H)-ONE

A method for treating a cancer, comprising administering to a patient having a cancer a crystal form of Compound 1

• wherein the cancer is glioblastoma multiforme, head and neck squamous cell carcinoma, castration-resistant prostate cancer, Ewing's sarcoma, chronic lymphocytic leukemia or small lymphocytic lymphoma.

A pharmaceutical composition comprising a crystal form of Compound 1

• and one or more pharmaceutically acceptable excipients or carriers, each independently selected from carboxymethyl cellulose, cellulose, lactose, magnesium stearate, starch, and stearic acid.