Study: Adding Pembrolizumab Strengthens Treatment for Head and Neck Cancer

Durable responses mark a significant advancement over chemotherapy, which may have only been effective for 9 to 10 months.

Research from a University of Cincinnati clinical trial has found that the addition of pembrolizumab (Keytruda) to standard of care treatment regimens for head and neck cancer increased survival rates.

Pembrolizumab is an antibody commonly used in immunotherapy regimens for a variety of cancers, including head and neck cancer. The drug targets receptors that typically work to turn off the human immune system after fighting off an illness-causing foreign substance.

“Once the virus or infection is cleared, you have to have a way to turn your own immune system off, to tell it that the infection is gone and it’s time to calm down,” said lead author Trisha Wise-Draper, MD, in the press release.

Tumor cells have evolved to kick these receptors into overdrive, which blocks immune cells from recognizing that tumor cells are foreign objects that should be attacked. Pembrolizumab, however, blocks the interaction and keeps immune cells working, which then leads the immune cells to attack the cancerous cells like they are supposed to.

Pembrolizumab has been developed as a treatment for a wide array of cancers and has shown early success as a treatment for head and neck cancers that have spread or returned after initial therapy. Early studies have shown efficacy for approximately 20% of patients treated, according to the study.

“And although we’re careful to say cure, it does result in what is called ‘durable responses,’” Wise-Draper said in the press release.

These durable responses mark a significant advancement over chemotherapy, which may have only been effective for 9 to 10 months, Wise-Draper said.

Based on these early data, the team of researchers aimed to determine whether pembrolizumab would work as an initial treatment that would prevent the cancer from recurring. Patients with head and neck cancer who usually receive standard of care treatments see the cancers return between 30% and 50% of the time, according to the study.

“So instead of waiting for them to come back, could we try to prevent them from coming back?” Wise-Draper said in the press release. “If the cancer came back, they were much harder to cure the second time and had a lot of failure in that group. So, we asked if we could add this immunotherapy, the pembrolizumab, and decrease that risk of cancer coming back.”

Patients enrolled in the trial received 1 dose of pembrolizumab before surgery and were evaluated for risk status before being grouped into intermediate- and high-risk groupings after surgery. Patients were considered high risk if part of the tumor was left behind after surgery or was not contained in a lymph node. All patients continued to receive the appropriate standard of care, with 6 more doses of pembrolizumab also administered after surgery.

In 50% of patients, treatment with pembrolizumab caused tumors to begin to die before surgery. Notably, this was a better rate than what was found when the drug was given for metastatic or recurrent head and neck cancer.

“We could see that a lot of these tumors were dying even after that first dose of pembrolizumab,” Wise-Draper said in the press release. “That was pretty exciting, because that was higher than expected.”

According to the study, fewer than 70% of patients in the intermediate group who were treated with radiation alone after surgery reported 1-year disease-free survival when treated with both radiation and pembrolizumab. Among the group of patients in whom the drug began to kill the tumor prior to surgery, 100% reported 1-year disease-free survival.

“It was a really strong predictor of patients who are going to do well on this treatment,” Wise-Draper said in the press release. “Hopefully that is going to help design trials to better understand who is going to respond and who is not.”

Identifying a reliable predictor could also help determine how treatments can be adjusted for patients who receive surgery, pembrolizumab, chemotherapy, and radiation, and who do not respond well to any of the treatments.

“That’s really where the research is going now, is trying to understand what are those biomarkers between the responders versus the non-responders and how we can develop new and better targeted therapies,” Wise-Draper said in the press release. “We have a couple of identified markers that will help us going forward, but we’re still doing a lot of research in that area.”

REFERENCE

Immunotherapy drug bolsters head and neck cancer treatment. News release. University of Cincinnati; February 28, 2022. Accessed March 2, 2022. https://www.uc.edu/news/articles/2022/02/immunotherapy-drug-shows-promise-in-clinical-trial.html