The phase Ib expansion evaluated BI 894999 in patients with advanced solid tumors, including CRC, NUT carcinoma, metastatic castration-resistant prostate cancer (mCRPC), and small-cell lung cancer (SCLC), using the MTD of schedule B and schedule C. BET inhibitors were developed as a potential treatment for NUT carcinoma, which is driven by BRD-NUT fusion oncoproteins, most commonly BRD4-NUT. The gene discussed is DNER; the disease is small cell lung carcinoma.