The combination was tested at the RP2D of Taselisib (2 mg) and Palbociclib (125 mg given 3 weeks on, 1 week off). Patients had a median of 4 prior treatments. There was modulation in pRb, pAKT, pGSK3β levels analyzed in the plasma and in tumor biopsies post-treatment. The combination was well tolerated, with promising anti-tumor activity and efficacy in these patients (n = 20). The gene discussed is RB1; the disease is neoplasm.