Efficacy of the mRNA-Based BNT162b2 COVID-19 Vaccine in Patients with Solid Malignancies Treated with Anti-Neoplastic Drugs

SIMPLE SUMMARY: Cancer patients undergoing active treatment may be more vulnerable to COVID-19 due to the effects of the malignant disease and the anti-cancer treatment. Assessing COVID-19 vaccine efficacy in protecting these patients from SARS-CoV-2 infection, is important due to the worldwide pandemic reaching an unprecedented third surge. Cancer patients on active neoplastic treatment had a reduced antibody response following immunization with the BNT162b2 vaccine, manifested as significantly more seronegative results and lower antibody levels compared with those of non-cancer individuals. The risk of a negative serological response was 7.35 times higher in patients on active anticancer treatment. This impaired serological response was mostly attributed to chemotherapy treatment. Cancer patients receiving non-chemotherapy treatments had a similar serologic response as those without cancer. Vaccinated cancer patients treated with chemotherapy might not be protected against SARS-CoV-2 infection and may need to continue exercising precautionary measures such as social distancing and facial masking. ABSTRACT: The BNT162b2 vaccine was shown to be highly effective in reducing the risk of COVID-19 infection in healthy individuals and patients with chronic disease. However, there are little data regarding its efficacy in patients treated for cancer. We analyzed the humoral response following vaccination with the second dose of BNT162b2 in 140 patients with solid malignancies who were receiving anti-cancer therapy at the time of vaccination and 215 participants who had not been diagnosed with cancer. Multivariate analysis was performed, followed by matching the two groups by age, gender and days from vaccination. The humoral response in the cancer patient group was significantly lower than in the non-cancer group: 20/140 seronegative (14.3%) vs. 3/215 (1.4%), p < 0.001; median IgG levels 2231 AU/mL (IQR 445-8023) vs. 4100 (IQR 2231-6774) p = 0.001 respectively. The odds ratio for negative serology results in cancer patients adjusted by age and gender was 7.35 compared to participants without cancer. This effect was observed only in chemotherapy treated patients: 17/73 seronegative (23.3%) vs. 3/215 (1.4%), p < 0.001; median IgG 1361 AU/mL vs. 4100, p < 0.001 but not in patients treated with non-chemotherapeutic drugs. Reduced immunogenicity to COVID-19 vaccine among chemotherapy-treated cancer patients, raises the need to continue exercising protective measures after vaccination in these patients.