Source: MedPage Today
Author: Mark L. Feurst
Two new studies show the profound impact of a combined vaccine and anti-programmed death-1 (PD-1) antibody approach in the treatment of human papilloma virus (HPV)-related cancers.
HPV causes nearly all cervical cancers, as well as most oropharyngeal, anal, penile, vulvar, and vaginal cancers. HPV16 and HPV18 are the leading viral genotypes that increase cancer risk. Given the viral cause of these cancers, immunotherapy has been considered a strong potential approach.
Many patients with the HPV16 and HPV18 subtypes of head and neck squamous cell carcinoma have good outcomes from treatment that includes surgery or chemotherapy and radiation. Although anti-PD-1 therapy is approved for patients who do not respond to treatment or who develop metastatic disease, it benefits only about 15% of patients. The theory, therefore, is that a vaccine could potentially boost the immune systems of patients with HPV-related head and neck cancer, opening the door for better responses to other existing therapies.
Vaccine + Nivolumab in Phase II Study
In the first study, a phase II trial, a tumor-specific vaccine combined with the immune checkpoint inhibitor nivolumab was found to shrink tumors in patients with incurable HPV-related cancers.
“Ours are the first results with this particular approach,” Bonnie Glisson, MD, of the Department of Thoracic Head and Neck Medical Oncology at the University of Texas MD Anderson Cancer Center in Houston, told the Reading Room. “The rates of response and survival are approximately double what have been observed with nivolumab given alone to similar patients. These results will lead to larger, randomized clinical trials of this combination.”
Vaccines specific to HPV antigens found on tumors had previously sparked a strong immune response, but had not by themselves been active against established cancers, she noted.
“Vaccines are revving up the immune system, but the immunosuppressive tumor microenvironment probably prevents them from working. Our thinking was that inhibition of programmed death-1 (PD-1) would address one mechanism of immunosuppression, empowering the vaccine-activated T lymphocytes to attack the cancer.”
Glisson and colleagues combined the vaccine ISA101, which targets peptides produced by the strongly cancer-promoting HPV16 genotype of the virus, along with nivolumab, a checkpoint inhibitor that blocks activation of PD-1 on T cells.
The single-arm, single-center clinical trial included 24 patients with incurable HPV-16–positive cancer who were followed for 12.2 months. The vaccine was given subcutaneously on days 1, 22, and 50. A nivolumab dose of 3 mg/kg was given intravenously every 2 weeks beginning on day 8 for up to 1 year. Of the 24 patients with recurrent HPV16-related cancers, 22 had oropharyngeal cancer, one had cervical cancer, and one had anal cancer. The overall response rate was 33% (eight patients), and the median duration of response was 10.3 months. Five of eight patients remain in response, the team reported.
The overall median survival was 17.5 months, progression-free survival was 2.7 months, and 70% of patients survived to 12 months.
Grades 3 to 4 toxicity occurred in two patients (asymptomatic grade 3 transaminase level elevation in one patient and grade 4 lipase elevation in one patient), requiring discontinuation of nivolumab therapy. The researchers observed side effects expected from the two treatments separately, but said they were encouraged to see no sign of synergistic side effects caused by the combination.
“The combination was very well tolerated as opposed to other immunotherapy combinations such as combined blockade of PD-1 and CTLA-4,” Glisson said. “The vaccine did stimulate a strong HPV-specific immune response in peripheral blood T cells, although this was not correlated with response or survival. This suggests that other immune-suppressive factors in the tumor environment are contributing to immune evasion.”
Randomized clinical trials of the vaccine and anti-PD1 combinations for cervical and oropharyngeal cancer are ongoing, she added. “These are promising data that will be confirmed in a randomized trial. Positive results could lead to marketing of the first therapeutic HPV vaccine.”
Vaccine Helps T cells Infiltrate HPV-related Head and Neck Cancer
In the second study, another vaccine was shown to boost antibodies and T cells to help them infiltrate tumors and fight off HPV-related head and neck cancer. This approach might complement PD-1 or programmed death-ligand 1 inhibition in HPV-associated head and neck cancers to improve therapeutic outcomes, explained the study’s lead author, Charu Aggarwal, MD, MPH, of the Perelman School of Medicine at the University of Pennsylvania.
“We wanted to know if this vaccine can boost the immune systems of patients with HPV-related head and neck cancer, potentially opening the door for better response rates to other existing therapies. Our findings show that we can.”
Aggarwal and colleagues conducted a Phase Ib/II safety, tolerability, and immunogenicity study of immunotherapy with MEDI0457, a DNA immunotherapy targeting HPV16/18 E6/E7 with interleukin-12 encoding plasmids. The vaccine was delivered via electroporation to 21 patients. One group of patients received one dose before surgery, followed by three doses after surgery. The second group received four doses following chemotherapy and radiation.
Eighteen of the 21 patients (86%) showed elevated T cell activity that lasted at least 3 months after the final vaccine dose, the team reported. Five tumors were biopsied both before and after one dose of the vaccine, and there was evidence of T cells reacting with antigens contained in the vaccine in all five of these samples. One patient who developed metastatic disease and was treated with anti-PD-1 therapy developed a rapid and durable complete response that has lasted more than 2 years.
“We have not seen that kind of infiltration with just one dose of a vaccine before. These findings open the door for utilizing targeted immunotherapy approaches against specific cancer-causing targets like HPV,” said Aggarwal, adding that the vaccine was well tolerated, with no serious side effects reported.
“This response suggests that the vaccine may, in some manner, prime the immune system, potentially boosting the effects of subsequent anti-PD-1 therapy,” she explained, noting that a multi-site clinical trial is now open to patients with metastatic HPV-associated head and neck cancer, who will receive a combination of the vaccine with anti-PD-1 therapy.
Previously, the CheckMate-141 trial tested nivolumab in 361 patients with recurrent or metastatic, chemotherapy-refractory squamous cell head and neck cancer, and the results led to FDA approval in that setting. Sixty three of these patients were HPV16-positive, and the overall response rate among this group was 15.9%, with a median overall survival of 9.1 months.