The following article features coverage from the European Society for Medical Oncology (ESMO) Congress 2021. Click here to read more of Cancer Therapy Advisor’s conference coverage.

Most patients with solid tumors mount an “adequate” response to 2 doses of the Moderna COVID-19 vaccine, regardless of recent anticancer treatment, according to a presentation at the European Society for Medical Oncology (ESMO) Congress 2021.

The findings, from the VOICE trial ( Identifier: NCT04715438), were presented by Sjoukje Oosting, MD, PhD, of the University Medical Center Groningen in the Netherlands.

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The prospective, multicenter, noninferiority trial enrolled adults with and without solid tumor malignancies, all of whom had a life expectancy of more than 12 months. Patients with hematologic malignancies and those who previously had COVID-19 were excluded.

The patients were divided into 4 cohorts:

  • Individuals without cancer (n=240)
  • Cancer patients who received an anti-PD1/PD-L1 antibody (n=131)
  • Cancer patients treated with cytotoxic chemotherapy alone, in combination regimens, or with radiotherapy (n=229)
  • Cancer patients treated with an anti-PD1/PD-L1 antibody in combination with cytotoxic chemotherapy (n=143).  

The most recent immunotherapy administration had to be within 3 months before the first vaccination, and the most recent chemotherapy administration had to be within 4 weeks before the first vaccination.

Participants received 2 doses of the Moderna COVID-19 vaccine (mRNA-1273) 28 days apart.


The primary endpoint was SARS-CoV-2 spike S1-specific immunoglobulin G serum antibody response, defined as more than 10 binding antibody units (BAU) per ml, 28 days after the second vaccination.

This endpoint was met in 100% of control individuals, 99.2% of the immunotherapy group, 97.4% of the chemotherapy group, and 100% of the chemo-immunotherapy group.

The cancer patients’ responses were noninferior to the response in the control individuals, Dr Oosting said.

She noted, however, that the concentration of binding antibodies needed to provide protection from COVID-19 isn’t known. On the other hand, neutralizing antibody levels are known to be predictive of protection from symptomatic COVID-19.

Therefore, the researchers assessed the correlation between neutralizing antibody titers and binding antibody concentrations. To distinguish between suboptimal and adequate responders, the researchers defined a cutoff of 300 BAU per ml, based on neutralizing capacity.

“We found this an acceptable threshold because only 3% of the participants had a binding antibody concentration of more than 300 while they were neutralization negative,” Dr Oosting explained.

Applying this threshold, the antibody response was considered adequate after the first vaccination in 66% of the control individuals, 37.1% of the immunotherapy group, 32.5% of the chemotherapy group, and 33.3% of the chemo-immunotherapy group.

At 28 days after the second vaccination, the proportion of patients with an adequate response increased to 99.6% in the control group, 93.1% in the immunotherapy group, 83.8% in the chemotherapy group, and 88.8% in the chemo-immunotherapy group.

“Most patients have an adequate response after 2 vaccinations, but there is a significant minority that does not reach that,” Dr Oosting pointed out.

She added that spike-specific T-cell responses were detected in 42.9% of nonresponders, 47.3% of suboptimal responders, and 70.5% of adequate responders.


There were no significant differences in systemic adverse events (AEs) between the groups, but systemic AEs were more common after the second vaccination in all groups.

There were 16 serious adverse events, most related to infection or fever.

There were 14 immune-related adverse events, which is in line with what would be expected in cancer patients who have not been vaccinated, Dr Oosting said.

There were 10 deaths — 8 due to progressive disease, 1 due to pneumonitis, and 1 due to acute myeloid leukemia.

“Vaccination with mRNA-1273 is safe in patients receiving immunotherapy, chemotherapy, or the combination for a solid tumor,” Dr Oosting said. “The seroconversion rate is very high after 2 vaccinations, and the study met its primary endpoint. It’s not inferior compared to the controls.”

Longer follow-up will reveal whether the duration of response differs between patients with and without cancer, Dr Oosting said.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Read more of Cancer Therapy Advisor’s coverage of ESMO 2021 by visiting the conference page.


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. Presented at: European Society for Medical Oncology (ESMO) Congress 2021; September 16-21, 2021. Abstract LBA8.