The Pfizer-BioNTech vaccine appears effective for preventing COVID-19 in patients with solid tumors receiving active cancer treatment, according to research published in JAMA Oncology.

Researchers observed “durable cellular and humoral responses” to the vaccine as well as no confirmed cases of COVID-19 in the patients studied.

The researchers did note that this study was conducted before the omicron wave of the pandemic, which may be a limitation. 

For this study, researchers evaluated responses to COVID-19 vaccination in 169 patients with solid tumors who were receiving anticancer treatment at the time of their first vaccination. 

The researchers assessed humoral responses at 6 months post-vaccination using an S1/S2 immunoglobulin G assay, and they assessed T-cell responses using an ELISA assay. The researchers also assessed COVID-19 status at 1 year.

All patients had received at least 2 doses of the Pfizer-BioNTech COVID-19 vaccine, and a subgroup had received a booster dose. The patients’ mean age was 66 years, 57% of them were men, and 81% had metastatic disease. 

The most common cancers were gastrointestinal (33%), lung (23%), breast (17%), and genitourinary (12%) cancers. Patients were receiving chemotherapy (57%), a biological agent (36%), immunotherapy (37%), or a combination of treatment types.

The researchers found that patient age, sex, and tumor type did not predict cellular response to vaccination. Chemotherapy was associated with humoral response, but there was no association between spot-forming units (SFUs) and treatment type. 

Serological response was significantly associated with cellular response. However, 5 of the patients who were seronegative had SFU levels that were equal to or greater than the mean SFU level of the seropositive patients.

After receiving a booster dose, 67% of patients had a significant cellular immune response (P =.02), and 100% had an increase in antibody levels (P <.001).

At 1 year after vaccination, no cases of COVID-19 had been reported. 

“Taken together, these results suggest that, in patients with solid tumors, the BNT162b2 vaccine exerts a cellular and humoral sustainable response that is manifested by a low infectivity rate,” the researchers wrote.

Reference

Waldhorn I, Holland R, Goshen-Lago T, et al. Long-term immunogenicity of BNT162b2 vaccine in patients with solid tumors. JAMA Oncol. Published online April 22, 2022. doi:10.1001/jamaoncol.2022.1467