A Study of ALRN-6924 for the Prevention of Chemotherapy-induced Side Effects (Chemoprotection)

Phase 1b, Part 2 NSCLC Inclusion Criteria: * Histopathological confirmation of Stage IV NSCLC of adenocarcinoma histology. Cytological diagnosis of NSCLC is acceptable if sufficient tumor tissue is available for p53 mutation analysis. FDA approved liquid biopsies are also acceptable. * Presence of one or more p53 mutations. * Measurable disease using RECIST 1.1. * Eastern Cooperative Oncology Group (ECOG) Performance Status 0-1. * Adequate hematological status. * Adequate hepatic and renal function. Phase 1b, Part 2 NSCLC Exclusion Criteria: * Advanced NSCLC tumors with EGFR mutations or ALK re-arrangement or other actionable genetic aberrations for which an approved targeted treatment is available. Patients who received prior treatment with EGFR or ALK inhibitors or other systemic drugs or immunotherapy for NSCLC are not eligible. * Patients who are candidates for anti-PD-1 monotherapy in 1st line advanced NSCLC (e.g. tumors with high PD-L1 expression). * Presence of active central nervous system metastases and/or carcinomatous meningitis. * Significant weight loss (≥15% body weight) within the 4 weeks prior to enrollment. Phase 1b, Part 1 SCLC Inclusion Criteria: * Histopathological confirmation of ED SCLC that has recurred or been refractory to one line of treatment with standard platinum-based chemotherapy or immuno-chemotherapy. Patients who received immunotherapy after platinum-based chemotherapy are eligible. * Presence of one or more p53 mutations. * Measurable disease using RECIST 1.1. * Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2. * Adequate hematological status. * Adequate hepatic and renal function. Phase 1b, Part 1 SCLC Exclusion Criteria: * More than one line of prior chemotherapy for ED SCLC (prior immunotherapy is permitted, concurrent with or subsequent to first line chemotherapy). * Presence of active central nervous system metastases and/or carcinomatous meningitis. * Significant weight loss (≥15% body weight) within the 4 weeks prior to enrollment.