Incyte lands priority review for PD-1 inhibitor in anal cancer

The FDA has accepted Incyte’s PD-1 inhibitor retifanlimab for priority review in patients with locally advanced or metastatic squamous cell carcinoma of the anal canal (SCAC).

Incyte secured global rights to retifanlimab, then known as MGA012, from MacroGenics for $150 million upfront in 2017. Having seen PD-1 rivals corner many major indications, Incyte picked out a clutch of niche tumors in which to validate retifanlimab and get it registered while exploring its use in some more common diseases and in combination with its other oncology drugs.

The approach has landed Incyte an FDA priority review in locally advanced or metastatic SCAC patients who have progressed on, or who are intolerant of, platinum-based chemotherapy, teeing it up to win its first approval for retifanlimab by July 25.

Incyte is putting a bigger emphasis on SCAC than the clutch of companies that have already won FDA approval for PD-1/L1 drugs did. Checkpoint inhibitors are already used as second-line treatments of metastatic anal cancer, with the National Comprehensive Cancer Network adding Merck’s Keytruda and Bristol Myers Squibb’s Opdivo to its guidelines in 2018, but the data to support them are limited.  

Keytruda and Opdivo secured their positions on the treatment guidelines on the strength of clinical trials that enrolled 24 and 37 patients, respectively. Merck went on to test Keytruda in 112 more patients, but Incyte still sees an opportunity for retifanlimab.

Incyte positioned itself to seize the opportunity by running a phase 2 clinical trial in 94 subjects. The study linked retifanlimab to an objective response rate (ORR) of 14%. There were 12 partial responses and one complete response. The median overall survival was 10.1 months. While the ORR is similar to the results of studies of rival checkpoint inhibitors, Incyte has framed the choice to enroll HIV patients in its trial as a differentiator.

“There's a subgroup of patients who are HIV positive with this that have that unmet need and were addressed in our study, which hasn't been addressed in other studies. So we're very encouraged obviously by the data set and thus initiated a phase 3,” Incyte Executive Vice President Barry Flannelly told investors late last year. 

Incyte began the 300-subject phase 3 clinical trial in November. The study is advancing in parallel to efforts to get retifanlimab approved on the basis of midphase data and preparations to test the PD-1 drug in combination with IDO1 inhibitor epacadostat and FGFR inhibitor Pemazyre.