Naptumomab Estafenatox in Combination With Pembrolizumab Preceded by Obinutuzumab in Patients With Urothelial Cancers

Recommended Phase 2 Dose (RP2D) of the combination of NAP/pembrolizumab preceded by obinutuzumab to find the

The main purpose of this study is to test the safety and tolerability of naptumomab
 estafenatox (NAP), the planned experimental (investigational) drug, in combination with
 pembrolizumab following a single pretreatment with Obinutuzumab (Obi), and determine its side
 effects and effects on urothelial cancer. It is hypothesized that adding NAP will make
 pembrolizumab more effective. Participants will receive 2 infusions of Obi prior to the
 treatment of NAP in combination with pembrolizumab. This treatment is given in 21-day cycles
 for 6 cycles with NAP administered daily for 4 consecutive days, Days 1-4, + pembrolizumab
 given on day 2 of each cycle. After these six cycles of therapy, participants will continue
 to receive pembrolizumab every 3 weeks, without NAP, for a total number of up to 34
 pembrolizumab administrations since cycle 1. After the treatment of Obi is completed,
 participants will start NAP in combination with pembrolizumab and continue that treatment in
 a 28 day cycle period. NAP will be given for a total of 6 cycles and pembrolizumab will be
 given every 21 days for a total of up to 2 years. After stopping treatment, participants have
 follow-up visits or phone calls about every 12 weeks until the study is closed.