A 132-patient study indicates that pembrolizumab immunotherapy is effective for patients with recurrent or metastatic head and neck cancer (HNC).

The findings may fill a large unmet need for better treatments in this disease.

Overall, 57% of patients experienced some tumour shrinkage, and 24.8% had a marked decrease in tumour size known as partial or complete response.

Pembrolizumab was active across a wide range of patient subgroups including those with HPV-positive and HPV-negative HNC.

“The efficacy we saw was remarkable – pembrolizumab seems to be roughly twice as effective, when measured by response, as our only targeted therapy cetuximab. Unlike EGFR-inhibitors, where data at this meeting suggest potentially less efficacy in HPV-positive tumours, pembrolizumab showed similar levels of activity in both HPV-positive and HPV-negative tumours,” said lead study author Tanguy Seiwert, MD, an assistant professor of medicine, and associate HNC program leader at the University of Chicago in Chicago.

“We have high hopes that immunotherapy will change the way we treat head and neck cancer.”

HNC is the sixth most common cancer in the United States and worldwide.

Recurrent/metastatic HNC is incurable and carries a poor prognosis with a median overall survival of approximately 10-12 months.

Standard initial treatment involves platinum based doublet chemotherapy with or without cetuximab, the only approved targeted therapy for HNC.

Second-line options include methotrexate, docetaxel, and cetuximab.

Only 10-13 percent of patients respond to single-agent cetuximab, and recent data suggest that efficacy of cetuximab in HPV-positive tumours may differ from efficacy in HPV-negative tumours.

While chemotherapy can be effective, it also causes significant side effects.

In the present study, 132 patients with recurrent or metastatic squamous cell carcinoma of the head and neck received a fixed dose of pembrolizumab of 200 mg given as an infusion every three weeks.

Of these patients, 59% had received two or more lines of prior therapy.

Patients were not selected for this study based on PD-L1 status (a candidate biomarker that predicts response to PD-1/PD-L1 immunotherapy, such as pembrolizumab).

The majority (57%) of patients experienced some decrease in tumour size.

The overall objective response rate was 24.8% (26.3% in HPV-negative patients and 20.6% in HPV-positive patients).

“It is important to note that response rate may underestimate the rate of benefit in patients, and ultimately we need to assess survival. We know from other diseases where the experience with immunotherapy is larger, that patients who have disease stabilisation or even initially experience disease progression upon receiving immunotherapy ultimately may derive significant benefit that can translate into longer survival,” stated Dr. Seiwert.

Pembrolizumab was well tolerated, with serious side effects occurring in less than 10% of patients.

The most common side effects were fatigue, rash, and itching; more serious immune-related side effects such as inflammation of lungs (pneumonitis) and colon (colitis) were observed in a small number of patients.

Two ongoing phase III studies are evaluating pembrolizumab versus standard treatment in patients with recurrent/metastatic head and neck cancer.

Watch the press conference video or see comment from Dr Lynn Schuchter.

Source: ASCO