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

Inclusion Criteria: * Willingness to provide written informed consent * Individuals \>= 18 years of age * Histologically confirmed advanced local or metastatic esophogastric, hepatopancreaticobiliary, colorectal, or lung cancer diagnosis within 12 weeks of screening * Patients with weight loss as defined by international consensus criteria (documented or patient-reported): * ≥ 5% weight loss over the past 6 months * ≥ 2% weight loss with body mass index (BMI) \<20 kg/m\^2 or sarcopenia * Planned or ongoing first-line palliative antineoplastic therapy (cytotoxic chemotherapy, targeted therapy, immunotherapy, combinations) with or without radiation therapy and have not started the second cycle of first-line palliative antineoplastic therapy. Patients may have received adjuvant antineoplastic therapy at least 6 months prior to screening * Able to ambulate independently with or without assistive devices (e.g., cane, walker) * In the case of brain metastases, the individual must be asymptomatic or previously treated with a full cycle of therapy with recovery from any acute effects of radiation therapy or surgery before screening. Such individuals must have discontinued corticosteroid treatment and be neurologically stable for at least 4 weeks before screening * Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 * Able and willing to discontinue the use of any drug or over-the-counter (OTC) product that may interact with the study drug (within a period suffic…