This is a Phase 1a/1b, first time in human (FTIH), open-label, dose escalation and expansion study to evaluate the safety, tolerability, and preliminary efficacy of CT-202 (study drug), a humanized T cell engaging bispecific antibody targeting nectin-4, in participants with nectin-4 expressing recurrent, unresectable or metastatic refractory/resistant TNBC, CRC, or UC. Results of the study including PK, PD, efficacy, and safety will be used in the RP2D determination.

Phase 1a Dose Escalation: Will follow a Bayesian Optimal Interval (BOIN) design (Liu, 2015) with step up dosing (i.e. priming followed by full doses of CT-202), Q2W administration schedule, and approximately 6 dose levels. Participants will continue study treatment until confirmed disease progression, the occurrence of unacceptable toxicity, withdrawal from the study or decision to discontinue treatment by the investigator.

Phase 1b Dose Expansion: Upon completion of the dose escalation Phase 1a, CT-202 may be evaluated at 2 or more dose levels and 2 or more dosing schedules in at least 4 but up to 6 expansion cohorts. The population(s) will include participants with the same tumor indications, or subsets, evaluated in the dose escalation phase (TNBC, CRC, or UC). Up to 15 participants will be assigned to each dosing cohort.

Based on the totality of data from Phase 1b, a RP2D for future clinical studies will be determined.

Inclusion Criteria:

• Participants with nectin-4-positive triple negative breast cancer, colorectal cancer, or urothelial cancer that have received standard therapies
• Participants with measurable disease per RECIST 1.1
• ECOG 0, 1, or 2 and life expectancy of ≥ 12 weeks
• Participants have adequate organ function.

Exclusion Criteria:

• History of severe skin toxicity
• Uncontrolled significant active infection or any medical or other condition that in the opinion of the Investigator would preclude the participant's participation in the study.
• Concurrent participation in another investigational clinical trial.