image of lungs with SARS-CoV-2 particles on them to indicate infection and lung damage from COVID-19
Credit: Peter Zelei Images / Getty Images

Drugs for nasopharyngeal cancer worked better in patients who received the Chinese vaccine SinoVac than in unvaccinated patients, according to a recent study by the Universities of Bonn, Germany, and Shanxi in the People’s Republic of China. These results are published as a “Letter to the editor” in the journal Annals of Oncology.

Patients with nasopharyngeal cancer are often treated with drugs that activate their immune system against the tumor. Until now, it was feared that vaccination against COVID-19 could reduce the success of cancer treatment or cause severe side effects.

“It was feared that the vaccine would not be compatible with anti-PD-1 therapy,” explains Jian Li of the Institute of Molecular Medicine and Experimental Immunology (IMMEI) at the University Hospital Bonn. “This risk is especially true for nasopharyngeal cancer, which, like the SARS-CoV-2 virus, affects the upper respiratory tract.”

Cancer cells can subvert the body’s immune response by effectively shutting down endogenous defense forces. That’s led to use of drugs that block PD-1 receptors. This enables the immune system to fight the tumor more effectively.

The Bonn and Shanxi team investigated whether COVID-19 vaccination impedes the effects of PD-1 inhibitors.

A total of 1537 NPC patients from 23 hospitals were included in the study. All patients were in a recurrent metastatic (RM) stage and received first-line anti-PD-1 therapy at the time of relapse or diagnosis of metastasis, with most receiving combination anti-PD-1 therapy and chemotherapy.

The study found that vaccinated patients responded better to cancer therapy.

A subset of 373 affected individuals had been vaccinated with the Chinese Covid vaccine SinoVac. “Surprisingly, they responded significantly better to anti-PD-1 therapy than the unvaccinated patients,” explains Christian Kurts, Director of IMMEI and member of the Transdisciplinary Research Area “Life & Health” and the Cluster of Excellence ImmunoSensation. “Furthermore, they did not experience severe side effects more often.”

The outcomes showed that 140 (9.1%) patients achieved complete remission, 503 (32.7%) partial remission, 526 (34.2%) stable disease, and 337 (21.9%) progressive disease. In this cohort, 373 (24.3%) patients were vaccinated with SinoVac, and were defined as the vaccinated subgroup.

Compared with the non-vaccinated subgroup, vaccinated patients showed a higher objective response rate and disease control rate following anti-PD-1 treatment, were more likely to experience mild treatment and vaccine-related adverse effects.

The researchers cannot say why the treatment was more successful after vaccination. “We assume that vaccination activates certain immune cells, which then attack the tumor,” says Qi Mei of Shanxi University Hospital. “We will now investigate this hypothesis further.”

The authors note that NPC is characterized by peritumoral immune infiltration in the upper respiratory tract and that the tumor microenvironment (TME) in nasopharyngeal cancer may recruit myeloid-derived suppressor cells (MDSCs) to escape immunotherapy. Researchers had wondered if this might also reduce the effect of COVID-19 vaccination.

They suggest reasons vaccination actually supports immunotherapy treatment include the possibility that CD4+ T cells might be activated and enter into the TME during vaccination, preventing MDSCs or regulatory T cells recruitment. It’s also possible that exhausted CD8+ T cells might be reactivated in the TME during vaccination, facilitating immunotherapy.

Nasopharyngeal cancer is quite rare, except in southern China and other countries in Southeast Asia, where the disease is widespread. In Taiwan, nasopharyngeal cancer is now considered one of the leading causes of death among young men.

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