Niraparib and Dostarlimab for the Treatment of Small Cell Lung Cancer and Other High-Grade Neuroendocrine Carcinomas

Inclusion Criteria

• •Participant must have unresected or locally advanced small cell lung cancer (Cohort 1) or high-grade neuroendocrine carcinoma (Cohort 2) confirmed by staff pathologist. High-grade neuroendocrine carcinoma of prostate (e.g. aggressive variant prostate cancer, small cell of prostate, etc.) are excluded
• •Patients must have had at least one prior line of systemic therapy directed at their malignancy
• •Participant must have an Eastern Cooperative Oncology Group (ECOG) performance status of =\< 1
• •Participant must be \>= 18 years of age
• •Absolute neutrophil count \>= 1,500/uL
• •Platelets \>= 100,000/uL
• •Hemoglobin \>= 9 g/dL
• •Serum creatinine =\< 1.5 x upper limit of normal (ULN) or calculated creatinine clearance \>= 60 mL/min using the Cockcroft-Gault equation
• •Total bilirubin =\< 1.5 x ULN (=\< 2.0 in patients with known Gilberts syndrome) OR direct bilirubin =\< 1 x ULN
• •Aspartate aminotransferase and alanine aminotransferase =\< 2.5 x ULN unless liver metastases are present, in which case they must be =\< 5 x ULN
• •International normalized ratio (INR) or prothrombin time (PT) =\< 1.5 x ULN unless patient is receiving anticoagulant therapy as long as PT or partial thromboplastin (PTT) is within therapeutic range of intended use of anticoagulants. Activated partial thromboplastin time (aPTT) =\< 1.5 x ULN unless patient is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants
• •Participant receiving corticosteroids may continue as long as their dose equivalent to 10 mg prednisone or less and is stable for least 4 weeks prior to initiating protocol therapy
• •Participant must agree to not donate blood during the study or for 90 days after the last dose of study treatment
• •Female participant has a negative serum pregnancy test within 7 days prior to taking study treatment if of childbearing potential and agrees use an adequate method of contraception from screening through 180 days after the last dose of study treatment, or is of nonchildbearing potential. Nonchildbearing potential is defined as follows (by other than medical reasons):
• •* \>= 45 years of age and has not had menses for \> 1 year
• •* Patients who have been amenorrhoeic for \< 2 years without history of a hysterectomy and oophorectomy must have a follicle stimulating hormone value in the postmenopausal range upon screening evaluation
• •* Post-hysterectomy, post-bilateral oophorectomy, or post-tubal ligation. Documented hysterectomy or oophorectomy must be confirmed with medical records of the actual procedure or confirmed by an ultrasound. Tubal ligation must be confirmed with medical records of the actual procedure, otherwise the patient must be willing to use an adequate barrier method throughout the study, starting with the screening visit through 180 days after the last dose of study treatment. Information must be captured appropriately within the site's source documents. Note: Abstinence is acceptable if this is the established and preferred contraception for the patient
• •* Pelvic irradiation
• •Participant must agree to not breastfeed during the study or for 180 days after the last dose of study treatment
• •Male participant agrees to use an adequate method of contraception starting with the first dose of study treatment through 180 days after the last dose of study treatment. Note: Abstinence is acceptable if this is the established and preferred contraception for the patient
• •Participant must be able to understand the study procedures and agree to participate in the study by providing written informed consent
• •Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial