To assess how CD38 expression is modulated by ICB, we utilized pre-clinical of SCLC derived from genetically engineered mouse models (GEMM)with conditional loss of Rb1, Trp53 (RP), Rb1, Trp53 and p130 (RPP) or Rb1, Trp53, and MYCT58A (RPM) closely resembling the human disease (9, 10). The gene discussed is CD38; the disease is small cell lung carcinoma.