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22-09-2021 | ESMO 2021 | Conference coverage | News

Adequate response to COVID-19 vaccine in people receiving anticancer therapy

Author: Shreeya Nanda


medwireNews: Administration of two doses of the Moderna (mRNA-1273) vaccine against COVID-19 elicits an adequate immune response in most, but not all, patients with a solid tumor treated with chemotherapy, immunotherapy, or both, indicate findings.

Speaking at the ESMO Congress 2021, Sjoukje Oosting (University Medical Center Groningen, the Netherlands) explained that the VOICE investigators examined the efficacy of SARS-CoV-2 vaccines in people receiving anticancer treatment as “chemotherapy and immunotherapy may impact the ability to mount an effective immune response to vaccination and could increase the risk of adverse events.”

Oosting reported that the study included four cohorts as outlined below:

  • 131 patients treated with PD-1 or PD-L1 inhibitor monotherapy;
  • 229 patients who had received cytotoxic chemotherapy, as monotherapy, in a combination, or alongside radiotherapy;
  • 143 patients treated with a PD-1 or PD-L1 inhibitor in combination with chemotherapy;
  • 240 cancer-free controls.

The most recent immunotherapy administration needed to have been within 3 months prior to the first vaccine dose, while this interval was 4 weeks for chemotherapy, she explained.

At day 28 after the second dose, an antibody response – defined as IgG antibody levels against the SARS-CoV-2 spike protein of 10 binding antibody units (BAL)/mL or higher – was achieved by a comparable proportion of participants in the immunotherapy, chemotherapy, chemoimmunotherapy, and control groups, at 99.2%, 97.4%, 100%, and 100%, respectively.

However, as the threshold at which binding antibodies provide protection against symptomatic COVID-19 infection is unknown, Oosting and colleagues used the neutralizing capacity of the antibodies to establish a cutoff of 300 BAU/mL for an adequate antibody response.

Application of this threshold identified 93.1% of immunotherapy-treated patients, 83.8% of those given chemotherapy, and 88.8% of chemoimmunotherapy-treated patients as adequate responders after receipt of both vaccine doses, compared with 99.6% of controls.

This meant that a respective 6.9%, 16.2%, and 11.2% of patients in the immunotherapy, chemotherapy, and chemoimmunotherapy groups had an inadequate response despite receiving two doses.

Of note, the proportion of participants with an adequate response – based on the 300 BAU/mL cutoff – after one dose was 37.1%, 32.5%, 33.3%, and 66.0% in the immunotherapy, chemotherapy, chemoimmunotherapy, and control cohorts, respectively.

Oosting and colleagues also assessed spike-specific T-cell responses, using the interferon-γ ELISpot assay, in all nonresponders (≤10 BAU/mL) and suboptimal responders (>10 to <300 BAU/mL) as well as a selection of the adequate responders. They found that that 42.9% of the seven nonresponders, 47.3% of the 55 suboptimal responders, and 70.5% of the 149 adequate responders had a T-cell response, as defined by at least a twofold increase in spots and at least 50 spot-forming cells per million peripheral blood mononuclear cells.

“Longer follow-up of our study will indicate if there is a difference in the duration of immune response between the patients and the controls,” commented the investigator.

Reporting on the safety, she noted that systemic adverse events, such as fever, headache, and myalgia, tended to occur more frequently and were more likely to be moderate or severe after the second than the first dose, with “no striking differences” between the cohorts.

Local adverse events, such as pain at injection site, “were infrequent and mostly mild,” Oosting added.

She pointed out that there were 16 serious adverse events, all in the cancer patient groups and most related to infection and fever, as would be expected in such a patient cohort, and 20 adverse events of special interest, including 10 deaths (primarily due to cancer progression) and four cases of thromboembolic events, of which two were deemed related to the vaccine.

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group

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ESMO Congress 2021; 16–21 September