Olanzapine for the Management of Cancer Associated Appetite Loss in Patients With Advanced Esophagogastric, Hepatopancreaticobiliary, Colorectal or Lung Cancer

PRIMARY OBJECTIVE: I. To assess the impact of olanzapine 2.5 mg versus (vs) placebo on the proportion of patients with locally advanced or metastatic EG, HPB, or lung cancers receiving first-line systemic standard-of-care (SOC) therapy with \>5% weight gain over 12 weeks. (Part A) SECONDARY OBJECTIVE: I. To evaluate the impact of olanzapine 2.5 mg and placebo vs olanzapine 5 mg on the proportion of patients with \>5% weight gain over 12 weeks. (Part A) II. To evaluate the impact of olanzapine 2.5 mg vs olanzapine 5 mg vs placebo on additional cancer cachexia-associated endpoints over 12 weeks (anorexia, nutritional status, physical function, patient-reported symptoms, QOL, safety and toxicity, and healthcare utilization) over 12 weeks. (Part A) OUTLINE: PART A: Patients are randomized to 1 of 3 arms. All three arms have an optional baseline computed tomography (CT) scan (timed with standard-of-care imaging) at baseline and optional monthly blood sample collections. ARM I: Patients receive a lower (2.5 mg) dose of olanzapine orally (PO) nightly for 12 weeks in the absence of unacceptable toxicity. Patients may choose to enroll in an additional 12 weeks of treatment (Part B). Patients may choose to participate to undergo CT scan and collection of blood samples on study. ARM II: Patients receive a higher (5 mg) dose of olanzapine PO nightly for 12 weeks in the absence of unacceptable toxicity. Patients may choose to enroll in an additional 12 weeks of treatment. Patients may choose to participate to undergo CT scan and collection of blood samples on study. ARM III: Patients receive placebo PO nightly for 12 weeks in the absence of unacceptable toxicity. Patients may choose to enroll in an additional 12 weeks of treatment. Patients may choose to participate to undergo CT scan and collection of blood samples on study. PART B: All patients receive a lower (2.5mg) dose of olanzapine PO nightly for 12 additional weeks in the absence of unacceptable toxicity. Patients may choose to participate in additional blood sample collections. After completion of study treatment, patients are followed up at 1 week.