Individuals with solid tumors had an appropriate, protective immune response to vaccination against SARS–CoV-2, at least with the mRNA-1273 vaccine, and side effects were no more common than in the general population, according to a large Dutch study.1 The study was reported during the European Society for Medical Oncology (ESMO) Congress 2021 by Sjoukje Oosting, MD, PhD, of the University Medical Center Groningen, the Netherlands.
The findings send a reassuring message to patients and their providers. “Vaccination with mRNA-1273 is safe in patients receiving immunotherapy, chemotherapy, or chemoimmunotherapy for a solid tumor. The seroconversion rate is very high after two vaccinations and is noninferior to controls,” said Dr. Oosting.
However, there is more concern with vaccination for patients with hematologic cancers, according to another study reported during the ESMO Congress, sponsored by The Royal Marsden and NHS Foundation Trust.2
Most patients have an antibody concentration increase after the second vaccination. Therefore, an additional booster may turn inadequate responders into adequate responders.— Sjoukje Oosting, MD, PhD
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Details of VOICE Study
Patients with cancer have been typically excluded from clinical trials conducted to develop and then approve current vaccines for COVID-19. Thus, there have been questions as to their true effectiveness as well as safety in the cancer population, explained Dr. Oosting.
The VOICE study attempted to explore the potential impact of chemotherapy and immunotherapy on the protection afforded by vaccination (Moderna’s two-dose mRNA-1273 vaccine) against COVID-19. It enrolled 791 patients (743 of whom were evaluable) from hospitals in the Netherlands. Within the population were four groups: one of people without cancer and three of patients with cancer treated with immunotherapy, chemotherapy, or both immunotherapy and chemotherapy. The most common malignancies varied according to the treatment received, but overall, they were lung, breast, gastrointestinal, skin, and urinary tract cancers.
In the study, participants received two mRNA-1273 vaccinations 28 days apart. The primary endpoint was SARS–CoV-2 spike S1-specific IgG serum antibody response, defined as at least 10 binding antibody units (BAU)/mL on day 28 after the second vaccination. Investigators also assessed the virus neutralizing capacity of these antibodies, SARS–CoV-2 spike-specific interferon-gamma T-cell response, and adverse events. To discriminate between suboptimal and adequate responders, the researchers defined a cutoff level at 300 BAU/mL, based on neutralizing capacity.
Two Doses Important
The study confirmed the importance of ensuring a complete, two-dose vaccination series. “Only one-third of patients had an adequate antibody response after just one vaccination,” reported Dr. Oosting. In healthy controls, about two-thirds had an adequate antibody response.
Testing 28 days after the second dose showed a SARS–CoV-2-binding antibody response in 99.6% of controls, 93.1% of the immunotherapy group, 88.8% of the combined-therapy group, and 83.8% of the chemotherapy group. This means that the proportion of “inadequate responders” was 0.4%, 6.9%, 11.2%, and 16.2%, respectively. In contrast, 28 days after the first dose, the antibody response was considered adequate in 66.0% of controls, 37.1% of the immunotherapy group, 33.3% of the chemoimmunotherapy group, and 32.5% of the chemotherapy group.
“Most patients have an antibody concentration increase after the second vaccination. Therefore, an additional booster may turn inadequate responders into adequate responders,” she suggested.
It was somewhat reassuring as well, Dr. Oosting noted, that even in participants with no response or a suboptimal response, spike-specific T-cell responses could be detected, suggesting this second line of defense may offer some protection. Spike-specific T-cell responses were detected in 42.9% of nonresponders, 47.3% of suboptimal responders, and 70.5% of adequate responders.
Systemic adverse events were not unusual and were more common after the second vaccination. They were not appreciably more common in the patients with cancer than in the healthy subjects, however, Dr. Oosting noted.
No serious grade ≥ 3 adverse events were observed among controls; they were seen in 10 of 544 patients treated for cancer. Grade ≥ 3 adverse events of special interest considered related to treatment included two thromboembolic events and one case of Stevens-Johnson syndrome in the patients with cancer. Grade ≥ 3 immune-related adverse events (chiefly, pruritus) were observed in two patients given immunotherapy and seven patients given chemoimmunotherapy.
DISCLOSURE: Dr. Oosting reported no conflicts of interest.
1. Oosting S, Van der Veldt AAM, GeurtsvanKessel CH, et al: Vaccination against SARS–CoV-2 in patients receiving chemotherapy, immunotherapy, or chemo-immunotherapy for solid tumors. ESMO Congress 2021. Abstract LBA8. Presented September 20, 2021.
2. Shepherd STC, Fendler A, Au L, et al: Adaptive immunity to SARS–CoV-2 infection and vaccination in cancer patients: The CAPTURE study. ESMO Congress 2021. Abstract 1557O. Presented September 20, 2021.