On Friday, Corbus Pharmaceuticals Holdings, Inc. (NASDAQ:CRBP) announced that data from its US and UK first-in-human dose escalation clinical study of CRB-701 (SYS6002) were presented at the American Society of Clinical Oncology Genitourinary Cancers Symposium.

The Phase 1 Western dose escalation study enrolled participants with metastatic urothelial cancer (mUC) and other solid tumors associated with Nectin-4 expression. These included several tumor types not previously explored in China. 

A December 2024 data cut (n=38) is being presented, of whom 26 participants were evaluable for efficacy.

The Western study enrolled participants in the top four dose cohorts used in China (1.8, 2.7, 3.6, and 4.5 mg/kg) and adopted the same Q3W regimen. 

Safety

• No dose-limiting toxicities were encountered during the dose escalation phase of both studies.
• CRB-701 was well tolerated, with most treatment-emergent adverse events being grade 1 or 2 in both studies.
  • Notably, few cases of peripheral neuropathy or skin rash have been reported to date in either study:Peripheral neuropathy: Western study (Grade 1-2: 5% (n=2/38), (Grade 3 or above: zero) was comparable to China study (Grade 1: 3% (n=1/37), Grade 2 or above: zero).
  • The combined peripheral neuropathy rate for both studies was 4% (n=3/75). 
  • Skin and subcutaneous disorders: 24% (n=9/38) in the Western study compared to 8% (n=3/37) in the China study. The combined rate for both studies was 16% (12/75) across all dose groups.
• Implementation of a proactive, preventative ocular toxicity protocol in the Western study yielded a lower incidence of ocular adverse events in the 2.7 mg/kg and 3.6 mg/kg (doses selected for optimization) in the Western study (38%) compared to the China study (66%).

The PK profile seen in the Western study was comparable to that generated in the China study. CRB-701 demonstrated a longer ADC half-life and lower free-MMAE exposure relative to enfortumab vedotin (EV).

Responses were observed in several tumor types, including previously unexplored HNSCC tumors.

The dose optimization phase of the Phase 1 Western study has commenced. Participants in HNSCC, cervical, and mUC tumors are being randomized to the 2.7 mg/kg and 3.6 mg/kg cohorts.

Price Action: CRBP stock is down 8.23% at $8.70 at the last check on Friday.

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