A Phase 1/1b of RNDO-564 Single Agent or in Combination With Pembrolizumab in Bladder Cancer and Other Solid Tumors Associated With Nectin-4

Inclusion Criteria: 1\) Eligible tumor types: Histologic documentation of incurable, locally advanced or metastatic solid tumors for which established standard systemic therapies are no longer effective (participant must have experienced progressive disease), are not tolerated, or in the opinion of the Investigator have been considered ineligible for a particular form of standard therapy on medical grounds or have been declined by the participant, with these tumor subtypes: A. Monotherapy and Combination Dose Escalation Arms: * RR la/mUC: Participants with urothelial cancer (transitional cell) with squamous differentiation or mixed cell types are eligible. Participants with upper tract disease, e.g., involving ureters, or renal pelvis, are eligible. Participants may have had up to 2 prior monomethyl auristatin E (MMAE)-containing therapies, assuming any existing peripheral neuropathy is Grade 2 or less. * NSCLC * HNSCC * CC * GC and GEJ * EC * TNBC B. Dose Optimization (Monotherapy and Combination Arms): * Limited to participants who have RR la/mUC, * Participants may have had up to 2 prior MMAE-containing therapies, assuming any existing peripheral neuropathy is Grade 2 or less 2. Participants must have measurable disease per response evaluation criteria in solid tumors (RECIST) v1.1. 3\. Adequate organ function Exclusion Criteria: 1. For Nectin-4 targeted agents (approved or investigational) * \> one prior Nectin-4 targeted agents 2. Peripheral neuropathy \> Grade 2 3. Participants with a history of, or with active, inflammatory skin disease, such as eczema, psoriasis that required or currently require biologics or oral steroids to control disease are ineligible.