“It is very important for cancer patients and their practitioners worldwide to know that they can be vaccinated against the coronavirus during their treatment and that this vaccination is safe,” says Liesbeth de Vries, professor of Medical Oncology at the UMCG and research leader of the VOICE-study (Vaccination against cOvid in CancEr).
In total, 503 patients with solid tumors and 240 controls, all partners of the patients, were vaccinated with two doses of the Moderna mRNA vaccine, four weeks apart. The participants received the first vaccination within three months after their most recent immunotherapy administration, or within four weeks after their most recent chemotherapy administration. The virus antibody response after two vaccinations was chosen as the primary endpoint in the study design. A positive response to the virus (seroconversion) was defined as a serum concentration of more than 10 binding antibody units per milliliter.
The results show that there were no differences between patients and controls 28 days after the second vaccine dose. All controls showed seroconversion, and this was also high for patients: 99.3% for immunotherapy, 97.4% for chemotherapy and 100% for chemo-immunotherapy. However, this was the result of seroconversion and the investigators were interested in a response that could predict protection from getting COVID-19. Based on the neutralizing capacity of the antibodies, a cut-off level at 300 binding antibody units per milliliter was considered to discriminate between a suboptimal and adequate response.
After two vaccinations, an adequate response was seen in 93.1% of immunotherapy treated patients, 83.8% of chemotherapy treated patients, and 88.8% of chemo-immunotherapy treated patients. In the control group, an adequate response was observed in 99.6% of controls. In most patients, the concentration of antibodies increased after the second vaccine dose. Therefore, in the small group of patients who did not reach the cut-off level of 300 binding antibody units after two vaccinations, a third vaccination might well result in an adequate response. This will be investigated in an extension of the study. Only one patient contracted COVID-19 in the period ending 28 days after the second vaccination. No unexpected side effects of vaccination were observed during the study.
The VOICE-study was set up when it became clear that COVID-19 can seriously impact patients with cancer. This raised the question whether COVID-19 vaccination is effective and safe for these patients. Chemotherapy can lower the immune response to vaccines, while little was known about immunotherapy, which potentially increases the immune response and might lead to side effects.
The participants in this study continue to be followed. Currently, data are collected at six months after vaccination. Moreover, T-cell response to vaccination will be studied, as the T cells may also confer protection against COVID-19.
The publication ‘A prospective multicentre COVID-19 vaccination trial in patients receiving chemotherapy, immunotherapy, or chemo-immunotherapy for solid tumours’ is soon expected to be published in Lancet Oncology (in press.) Co-researcher Sjoukje Oosting, medical oncologist at the UMCG, is presenting the results of the study on Monday 20 September in the presidential symposium at the congress of the European Society of Medical Oncology.
The study was funded by The Dutch Organisation for Health Research and Development (ZonMw).