Dr Gillenwater on Phase 1 Data for ASP-1929 Plus Pembrolizumab in HNSCC

Ann M. Gillenwater, MD, professor, the Department of Head and Neck Surgery, the Division of Surgery, The University of Texas MD Anderson Cancer Center, discusses safety and efficacy data from the phase 1b/2 ASP-1929-181 trial (NCT04305795) evaluating the antibody-dye conjugate ASP-1929 in combination with pembrolizumab (Keytruda) in patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC).

ASP-1929 consists of the antibody cetuximab (Erbitux) and the light-activatable dye, IRDye® 700DX and is activated using an investigational photoimmunotherapy platform. After ASP-1929 binds to EGFR on cancer cells, illumination with 690 nm red light locally activates the agent to cause selective necrosis of cancer cells.

Regarding safety, the combination was well tolerated, Gillenwater begins, adding that no grade 5 adverse effects (AEs) were observed. The most prominent AEs that were recorded included swelling and pain immediately after the treatment. However, these AEs tended to resolve within a few days, she explains. 

Regarding efficacy, evaluable patients (n = 17) experienced an overall response rate (ORR) of 29.4% (95% CI, 10.3%-56.0%), including a complete response rate of 17.6% and a partial response rate of 11.8%. Additionally, the 18-month overall survival (OS) rate was 53.5% (95% CI, 18.5%-79.3%). Notably, the median OS was not yet reached, and Gillenwater explains that this was a heavily pretreated patient population.

Looking forward, a phase 3 trial (NCT03769506) is evaluating ASP-1929 alone vs standard-of-care chemotherapy in patients with HNSCC who have received at least 2 prior lines of treatment. Although there has been difficulty recruiting patients onto the clinical trial, it is this phase 3 trial could lead to an FDA approval for ASP-1929, Gillenwater explains, adding that this approach was previously approved in Japan.