In SCLC models, our findings highlighted that absence of expression of the product of RB1 (the retinoblastoma protein, pRB) as a consequence of deletion, mutation, chromosomal loss or other mechanisms, as is the case in almost 90% of SCLC patients, might be a resistance marker for BET inhibition in SCLC. This evidence concerns the gene DNER and small cell lung carcinoma.