COVID-19 Vaccine “Boosts” Effectiveness of Anti-Cancer Treatment

A collaborative study has found that immunization with the vaccine SinoVac might improve responses to treatment in patients with nasopharyngeal cancer (NPC). The research is published as a “Letter to the Editor” in the journal Annals of Oncology.

Fears that COVID-19 vaccination may interfere with cancer treatment

Cancer cells are clever. They can adapt methods to avoid or divert the body’s immune response to protect their growth and prevent being destroyed. One approach is to target a protein found on T cells called programmed cell death protein 1, or PD-1. When PD-1 is bound to its ligand, PD-L1, it prevents T cells from killing malignant cells. Drugs called immune checkpoint inhibitors can block PD-1, releasing the “brakes” on the immune response such that the T cells’ ability to kill cancer cells is unleashed.

This type of therapy is often the standard of care for patients with NPC, where malignant cells form in the nasopharynx – the upper part of the throat behind the nose.

Vaccines also stimulate the immune response – including the PD-1 receptor. Therefore, the advent of COVID-19 vaccines in 2020 led to some concern from clinicians that vaccination against SARS-CoV-2 might also interfere with cancer treatment.

"It was feared that the vaccine would not be compatible with anti-PD-1 therapy," explains Dr. Jian Li, bioinformatics scientist at the Institute of Molecular Medicine and Experimental Immunology (IMMEI) at the University Hospital Bonn, in a news release. "This risk is especially true for NPC, which, like the SARS-CoV-2 virus, affects the upper respiratory tract."

Li and colleagues, in collaboration with partners from the People’s Republic of China, sought evidence regarding this fear. The researchers screened a total of 2,134 patients with NCP from 35 hospitals in late January 2021. Participants were required to meet the following criteria to enroll in the study:

• Confirmed NCP
• Received at least one dose of anti-PD-1 treatment
• Availability of medical records and willingness to follow up.

All clinical data was gathered at the point of enrolment, and the last date of follow-up for the study was June 25, 2022.

Subset of cancer patients receiving a COVID-19 vaccine responded better to cancer treatment

In total, 1,537 NCP patients were recruited to the study from 23 hospitals, with an average age of 45 years. Approximately 24% of the participants were female. From this cohort, a subset of 373 participants received a COVID-19 vaccine, SinoVac. “Surprisingly, they responded significantly better to anti-PD-1 therapy than the unvaccinated patients," explains Professor Christian Kurts, director of IMMEI and co-author of the study. "Furthermore, they did not experience severe side effects more often."

At this stage, the researchers cannot state why the treatment was more successful for patients after receiving a SinoVac vaccine. Their hypothesis is that immunization against SARS-CoV-2 activates specific immune cells that can enhance the attack of the tumor. “We will now investigate this hypothesis further,” says Professor Qi Mei from Shanxi Universital Hospital, co-author of the study.

Reference: Hua YJ, Liu YL, Wen K, et al. Potentially improved response of COVID-19 vaccinated nasopharyngeal cancer patients to combination therapy with anti-PD-1 blockade and chemotherapy. Ann. Oncol. doi: 10.1016/j.annonc.2022.10.002.

This article is a rework of a press release issued by the University of Bonn. Material has been edited for length and content.