Reduced RT Feasible in Chemo-Sensitive HPV-Associated Head and Neck Cancer

Patients with human papillomavirus (HPV)-associated head and neck cancers who respond well to induction therapy can receive substantially lower doses of radiation therapy (RT) and still achieve good safety and efficacy outcomes, according to a new phase II trial.

“Head and neck tumors that are caused by HPV respond well to therapy and can be cured reliably,” said Tanguy Seiwert, MD, of the University of Chicago Medicine, in a press release. “In fact, the effectiveness of combined treatment with radiation and chemotherapy has been so well documented that newer studies… are focused on selecting patients who can safely receive less treatment.” He presented results of the new OPTIMA trial at the 2018 Multidisciplinary Head and Neck Cancers Symposium, held February 15–17 in Scottsdale, Arizona.

A total of 62 patients with HPV-associated head and neck cancer were enrolled, and classified as either high-risk (34 patients) or low-risk (28 patients) according to several baseline factors. All patients underwent induction chemotherapy with carboplatin and nab-paclitaxel; those with a good response (at least a 50% reduction in tumor size for high-risk patients, and 30% reduction for low-risk patients) went on to receive a reduced dose of radiation (45 Gy chemoradiation [CRT] for high-risk patients, 50 Gy radiation alone for low-risk disease). Patients without a good response to induction therapy received a standard dose of CRT.

The 2.5-year overall survival rate was 85.7% in low-risk patients and 97% in high-risk patients. For progression-free survival, the 2.5-year rates were 91% and 93.8%, respectively. Those who received low-dose RT had a pathologic complete response rate of 94.7%; for those receiving low-dose CRT, the rate was 89.3%.

Grade 3 or higher mucositis occurred in 15% of low-dose RT patients, in 46.7% of low-dose CRT patients, and 63.6% of standard CRT patients (P = .01). Similar results were seen for grade 3 or higher dermatitis, with 0% of low-dose RT patients, 10% of low-dose CRT patients, and 45.5% of standard CRT patients (P = .002).

“This degree of de-escalation with high-risk patients is novel, as is selection using induction as the key component to reduce radiation doses and subsequent toxicities to such low levels,” Seiwert said. “In my opinion, treatment for HPV-positive disease should be de-escalated when possible, and induction is an ideal method to identify HPV-related head and neck cancer biology.”

Danielle Margalit, MD, of the Dana-Farber Cancer Institute in Boston, offered some expert perspective during a press conference; she highlighted that this approach not only reduces the radiation dose but also reduces the volume of radiated tissue. “Ultimately, these efforts should translate to better outcomes for our patients as they go into the survivorship phase,” she said.