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

The study will consist of four stages: 1) single agent dose escalation, 2) single agent dose optimization, 3) combination dose escalation and 4) combination dose optimization.

Stages 1 and 3 are dose escalation to investigate the safety and tolerability of increasing doses of RNDO-564 as a single agent and in combination with standard pembrolizumab treatment. Participants will be enrolled who have one of the following advanced solid tumors associated with Nectin-4: locally advanced/metastatic urothelial cancer (la/m UC), cervical cancer (CC), head and neck cancer (HNSCC), esophageal cancer (EC), gastric (GC) and gastroesophageal junction cancer (GEJ), triple negative breast cancer (TNBC), and non-small cell lung cancer (NSCLC). The cancer must not have responded well to previous cancer treatments. Stages 1, and 3 will be non-randomized.

Stages 2 (i.e., RNDO-564 single agent) and 4 (i.e., RNDO-564 in combination with pembrolizumab) are dose optimization and proof-of-concept stages to further investigate the safety and tolerability of at least 2 doses of RNDO-564 as a single agent and in combination with standard pembrolizumab treatment, and to investigate preliminary anti-tumor activity. Stages 2 and 4 will enroll participants with advanced urothelial cancer only. The cancer must not have responded well to previous cancer treatments. Participants will be randomized (1:1) into one of two arms which will evaluate two dose levels (as selected from Stages 1 and 3).

The study consists of a screening period, a treatment period, an end of treatment visit, a safety follow-up visit, and 60 and 90 days telephone follow-up after ending treatment. The treatment period will last for a maximum of 2 years.

Inclusion criteria

• 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.

• Adequate organ function

Exclusion criteria

• For Nectin-4 targeted agents (approved or investigational)

• > one prior Nectin-4 targeted agents
• Peripheral neuropathy > Grade 2
• 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.