We report the case of a 78-year-old man with mCRPC and Rai stage 0 CLL who sustained a 12-month decline in both PSA and white blood cell (WBC) count following treatment with APC8015-2 (an investigational form of sipuleucel-T), as part of the phase II ProACT clinical trial. Here, KLK3 is linked to B-cell chronic lymphocytic leukemia.