New research suggests that some patients with head and neck cancers can benefit by continuing treatment with an immunotherapy drug after their tumors show signs of enlargement according to investigators at Dana–Farber Cancer Institute and other organizations.

The researchers will report the findings at a poster session at the American Association for Cancer Research Annual Meeting.

The findings, from CheckMate 141, a phase 3 clinical trial, represent the first time that continued use of an immune checkpoint inhibiting drug has been shown to extend survival in patients whose head and neck tumors have grown during initial treatment with the drug.

The trial involved 139 patients with recurrent or metastatic squamous cell cancer of the head and neck that had progressed after treatment with nivolumab, a Food and Drug Administration–approved drug that works by blocking a molecule that deters immune system T cells from attacking tumor cells. Patients who were doing well clinically and were strong enough to handle further treatment – were given the opportunity to continue taking nivolumab. The others received no further nivolumab.

The 57 patients who continued with nivolumab had a median survival period of 12.7 months, compared to 6.1 months for the 82 patients did not. Almost one quarter of the patients in the first group had their tumors shrink – by more than 30 percent in two cases.

Adverse side effects of the treatment were similar in both groups, although patients who received nivolumab after progression of their disease had higher rates of disorders of the skin or tissue below the skin.

The results underscore that for nivolumab, as for some other immunotherapy drugs, “the benefit is often seen with increased survival, not necessarily tumor shrinkage an response rate,” said study lead author Robert Haddad, MD, leader of the Head and Neck Oncology Program at Dana–Farber. “Our findings suggest that for patients with head and neck cancer who are doing well enough, continuing nivolumab therapy after disease progression can often lengthen survival. For such patients, it can be a mistake to give up on these drugs too early, and clinical judgment should be exercised to determine whether it would be beneficial to continue therapy.”