Increasing neoadjuvant pembrolizumab from one to two cycles prior to surgery improved pathological response rates in patients with surgically resectable locally advanced, HPV-negative head and neck squamous cell carcinoma, reported Ravindra Uppaluri, MD, PhD, Dana-Farber/Brigham and Women's Cancer Center.

A previous study in which patients (36 total) received one neoadjuvant cycle of pembrolizumab followed by surgery two to three weeks later yielded a 22% rate of >50% pathologic response (tumour cell death and other evidence of response designated as pTR-2) and a 22% pTR-1 rate (10-49% pathologic response).

The new report was on a 28-patient phase 2 trial in which patients received two cycles of pembrolizumab 42 and 21 days prior to surgery.

Twelve of 28 patients (43%) experienced a pTR-2 and four (16%) of these patients had a major pathologic response including 1 complete response at the primary site.

Neoadjuvant therapy was well tolerated and clinical outcomes in this advanced disease population were excellent with only one recurrence noted to date.

The researchers said the data suggest that the frequency of pathologic responses to neoadjuvant pembrolizumab can be improved by increasing the number of cycles and the treatment interval.

Source: Dana-Farber Cancer Institute