Corbus Pharmaceuticals Holdings, Inc. announced that data from the first-in-human clinical study of CRB-701 (SYS6002) is being presented as a poster by the Company?s development partner CSPC Pharmaceutical Group at the 2024 American Society of Clinical Oncology Genitourinary Cancers Symposium(ASCO GU). The Phase 1 dose escalation study is being conducted in China and is enrolling participants with metastatic urothelial cancer (mUC) as well as participants with other solid tumors prospectively confirmed to have nectin-4 positive tumors. The study opened for enrollment in January 2023 and data through December 2023 from the first eighteen participants reflective of the first six dose cohorts (0.2-3.6mg/kg) will be shared.

Safety: CRB-701 was well-tolerated with the majority of adverse events being grade one or two and reversible. No adverse events above grade three were observed. There have been no dose discontinuations or reductions in the study to date.

There has been a singular participant that experienced a temporary dose interruption. The dose escalation is ongoing at cohort 7 (4.5 mg/kg). No cases of drug-related peripheral neuropathy or skin rash have been reported to date.

PK: Single dose PK suggested that TAb, ADC and MMAE increase in an approximate dose proportional manner. No obvious accumulation was observed on cycle 3, day 1. When compared to the exposures achieved with enfortumab vedotin (EV) at 1.25 mg/kg Q1W x21 days, CRB-701 (SYS6002) consistently demonstrated lower free MMAE concentrations. Efficacy: Dose level 5 (2.7 mg/kg) and above represents the predicted therapeutically relevant doses based on allometric scaling.

A mixed tumor population (n=7) receiving doses of 2.7 mg/kg or 3.6 mg/kg demonstrated an ORR of 43% (3 partial responses -2 unconfirmed and one non-responding participant with no-nectin-4 expression) and a disease control rate of 71%. The longest observed response to date is 11 cycles (~10 months) and ongoing. All nectin-4 positive mUC and cervical patients at doses = 2.7 mg/kg that were assessable at the time of the December 2023 data-cut off demonstrated levels of disease control and represent the CRB-701 (SYS6002) responsive population to date.

CRB-701 (SYS6002) is a next-generation antibody-drug-conjugate (ADC) targeting nectin-4, that contains a site-specific, cleavable linker and a homogenous drug antibody ratio of 2, using MMAE as the payload. Nectin-4 is a clinically validated, tumor-associated antigen in urothelial cancer. The Nectin-4 ADC PADCEV® (enfortumab vedotin-ejfv) is approved for use in late metastatic urothelial cancer and recently received an expanded label under an accelerated approval from the Food and Drug Administration for use in combination with KEYTRUDA® for patients with locally advanced or metastatic urothelial carcinoma who are ineligible for cisplatin-containing chemotherapy.