Patient description: The patient is a 47-year-old Asian woman complaining of persistent feelings of sadness. She lost interest in activities she used to enjoy. She states that her mood is mostly depressed for the past 3 weeks. She also lost her appetite , which led to about 5kg weight loss. She complains of loss of energy and feelings of worthlessness nearly every day. She is not using any drugs and she does not smoke. She doesn't drink alcohol. She used to exercise every day for at least 30 min. But she doesn't have enough energy to do so for the past 3 weeks. She also has some digestive issues recently. She is married and has 4 children. She is menopausal. Her husband was recently diagnosed with colon cancer and he is starting his chemotherapy. There is nothing remarkable in her past medical history and her drug history is only positive for Vit D3 1000 units daily. Her family history is negative for any psychologic problems. Her HAM-D score is 20.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Advanced Colorectal Carcinoma Advanced Digestive System Carcinoma Advanced Gastric Carcinoma Advanced Gastroesophageal Junction Adenocarcinoma Clinical Stage III Gastric Cancer AJCC v8 Clinical Stage III Gastroesophageal Junction Adenocarcinoma AJCC v8 Clinical Stage IV Gastric Cancer AJCC v8 Clinical Stage IV Gastroesophageal Junction Adenocarcinoma AJCC v8 Clinical Stage IVA Gastric Cancer AJCC v8 Clinical Stage IVA Gastroesophageal Junction Adenocarcinoma AJCC v8 Clinical Stage IVB Gastric Cancer AJCC v8 Clinical Stage IVB Gastroesophageal Junction Adenocarcinoma AJCC v8 Metastatic Colorectal Carcinoma Metastatic Digestive System Carcinoma Metastatic Gastric Carcinoma Metastatic Gastroesophageal Junction Adenocarcinoma Pathologic Stage III Gastric Cancer AJCC v8 Pathologic Stage III Gastroesophageal Junction Adenocarcinoma AJCC v8 Pathologic Stage IIIA Gastric Cancer AJCC v8 Pathologic Stage IIIA Gastroesophageal Junction Adenocarcinoma AJCC v8 Pathologic Stage IIIB Gastric Cancer AJCC v8 Pathologic Stage IIIB Gastroesophageal Junction Adenocarcinoma AJCC v8 Pathologic Stage IIIC Gastric Cancer AJCC v8 Pathologic Stage IV Gastric Cancer AJCC v8 Pathologic Stage IV Gastroesophageal Junction Adenocarcinoma AJCC v8 Pathologic Stage IVA Gastroesophageal Junction Adenocarcinoma AJCC v8 Pathologic Stage IVB Gastroesophageal Junction Adenocarcinoma AJCC v8 Postneoadjuvant Therapy Stage III Gastric Cancer AJCC v8 Postneoadjuvant Therapy Stage III Gastroesophageal Junction Adenocarcinoma AJCC v8 Postneoadjuvant Therapy Stage IIIA Gastroesophageal Junction Adenocarcinoma AJCC v8 Postneoadjuvant Therapy Stage IIIB Gastroesophageal Junction Adenocarcinoma AJCC v8 Postneoadjuvant Therapy Stage IV Gastric Cancer AJCC v8 Postneoadjuvant Therapy Stage IV Gastroesophageal Junction Adenocarcinoma AJCC v8 Postneoadjuvant Therapy Stage IVA Gastroesophageal Junction Adenocarcinoma AJCC v8 Postneoadjuvant Therapy Stage IVB Gastroesophageal Junction Adenocarcinoma AJCC v8 Stage III Colorectal Cancer AJCC v8 Stage IIIA Colorectal Cancer AJCC v8 Stage IIIB Colorectal Cancer AJCC v8 Stage IIIC Colorectal Cancer AJCC v8 Stage IV Colorectal Cancer AJCC v8 Stage IVA Colorectal Cancer AJCC v8 Stage IVB Colorectal Cancer AJCC v8 Stage IVC Colorectal Cancer AJCC v8 For Dose Escalation: Patients must have histologically or cytologically confirmed advanced or metastatic gastrointestinal (GI) cancers with Response Evaluation in Solid Tumors 1.1 (RECIST1.1) measurable disease who have progressed on at least one prior treatment for metastatic disease and for whom is considered a reasonable treatment option For Dose Expansion: Patients must have either Colorectal cancer who have previously progressed on irinotecan and tolerated an irinotecan dose equal to or greater than the RP2D OR Gastroesophageal cancer who have progressed on at least one first-line therapy for metastatic disease For Dose Expansion: Patients be willing to undergo biopsies for research purposes only. The accessible tumor can be the primary or metastatic tumor site. Both research biopsies should be taken from the same tumor site Patients must have progressive disease on at least first-line therapy for metastatic disease. Previous treatment with irinotecan is allowed Patients must be >= 3 weeks since completion of the previous chemotherapy regimen Eastern Cooperative Oncology Group (ECOG) performance status =< 1 Leukocytes >= 3,000/mcL Absolute neutrophil count >= 1,500/mcL  Patients with a history of prior treatment with an ATR inhibitor Patients with a history of other malignancy that could affect compliance with the protocol or interpretation of the results Patients who have had chemotherapy or radiotherapy within 4 weeks (6 weeks for nitrosoureas or mitomycin C) prior to entering the study Patients who have not recovered from adverse events due to prior anti-cancer therapy (i.e., have residual toxicities > grade 1) with the exception of alopecia Patients who are receiving any other investigational agents History of hypersensitivity or allergic reactions attributed to compounds of similar chemical or biologic composition to BAY 1895344, 5-FU, leucovorin, or irinotecan Patients receiving any medications that are substrates of CYP3A4 with a narrow therapeutic window or strong inhibitors/inducers of CYP3A4 are ineligible, if they cannot be transferred to alternative medication. Because the lists of these agents are constantly changing, it is important to regularly consult a frequently-updated medical reference. As part of the enrollment/informed consent procedures, the patient will be counseled on the risk of interactions with other agents, and what to do if new medications need to be prescribed or if the patient is considering a new over-the-counter medicine or herbal product Patients with uncontrolled intercurrent illness Patients with psychiatric illness/social situations that would limit compliance with study requirements Gastrointestinal pathology or history that adversely impact the ability to take or absorb oral medication