Testing the Combination of an Anti-cancer Drug, Iadademstat, With Other Anti-cancer Drugs (Atezolizumab or Durvalumab) at Improving Outcomes for Small Cell Lung Cancer

Inclusion Criteria: * Patients must have histologically or cytologically confirmed small cell lung cancer (SCLC) * Patients who have been treated with platinum etoposide chemotherapy plus either atezolizumab or durvalumab immunotherapy for at least 4 cycles, and no more than 6 cycles, with either a radiographic response or stable disease. Patients are eligible if a maximum of 2 cycles of atezolizumab or durvalumab were omitted with initial treatment * Age ≥ 18 years. Because no dosing or adverse event data are currently available on the use of iadademstat in combination with atezolizumab and durvalumab in patients \<18 years of age, children are excluded from this study * Body weight ≥ 50 kg * Patient is able to swallow oral medications * Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2 (Karnofsky ≥ 60%). This assessment for eligibility will take place after patients have received 4 cycles of standard of care (SOC) chemotherapy-ICI * Leukocytes ≥ 2,000/mcL * Lymphocyte count ≥ 500/mcL * Absolute neutrophil count ≥ 1,500/mcL * Hemoglobin ≥ 9 g/dL * Platelets ≥ 100,000/mcL * Albumin ≥ 3 g/dL * Total bilirubin ≤ 1.5 institutional upper limit of normal (ULN) * Aspartate aminotransferase (AST)(serum glutamic oxaloacetic transaminase \[SGOT\])/ alanine aminotransferase (ALT) (serum glutamic pyruvic transaminase \[SGPT\]) ≤ 3 × institutional ULN unless liver metastases are present, in which case it must be ≤ 5 × ULN * Glomerular filtration rate (GFR) ≥ 45 mL/min * H…