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.

All patients with cancer should be considered for further booster vaccination against COVID-19, particularly those with hematologic malignancies, according to researchers.

Patients with cancer are known to have an increased risk of severe outcomes from COVID-19, but humoral and cellular immunity following SARS-CoV-2 infection or COVID-19 vaccination have not been well characterized.

CAPTURE (ClinicalTrials.gov Identifier: NCT03226886) is a prospective, longitudinal cohort study of COVID-19 vaccine or SAR-CoV-2 infection-induced immunity in patients with cancer.

SARS-CoV-2 infections were confirmed by RT-PCR (reverse transcription-polymerase chain reaction) and ELISA (enzyme-linked immunoassay). Neutralizing antibody titers (NAbTs) against wild-type SARS-CoV-2 and variants of concern (Alpha, Beta, Delta) and SARS-CoV-2 specific T cells (SsT cells) were quantified.

Dr Scott Shepherd, of the Royal Marsden Hospital-NHS Foundation Trust in the United Kingdom, reported the study’s results at the European Society for Medical Oncology (ESMO) Congress 2021.

The study included an infection cohort of 118 patients, 89% with solid malignancy, who were SARS-CoV-2-positive after a median follow-up of 154 days. The majority (82%) had S1-reactive antibodies or had neutralizing antibodies (Nabs; 89%). NAbTs were lower against all variants of concern.

While S1-reactive antibody levels declined over time, NAbTs remained stable up to 329 days. Most patients had detectable SsT-cells (76% CD4-positive, 52% CD8-positive). Patients with hematologic cancer had impaired immune responses that were disease- and treatment-specific, but with evidence suggestive of compensation from T cells.

“SARS-CoV-2 infection leads to durable neutralizing antibody responses in solid cancer patients, but [antibody responses] are reduced in patients with hematologic malignancies,” Dr Shepherd reported. “Neutralizing responses to Beta and Delta variants of concern are reduced compared to wild-type SARS-CoV-2.”

The majority of patients with cancer have detectable cellular response to infection, but this was reduced in patients with hematologic malignancies. “Anticancer treatments do not generally impact immune response to SARS-CoV-2, with the exception of anti-CD20 monoclonal antibodies,” Dr Shepherd explained.

The researchers also evaluated a vaccine cohort of 585 patients after 2 doses of BioNTech-Pfizer’s BNT162b and Oxford/AstraZeneca’s AZD1222 vaccines, administered 12 weeks apart. Seroconversion rates after 2 doses were 85% and 54% in patients with solid malignancies and hematologic malignancies, respectively. A smaller proportion of patients had detectable Nabs against SARS-CoV-2 (Alpha, 62%; Beta, 54%; Delta, 49%) vs wild-type (84%), with corresponding significantly lower NAbTs. Patients with hematologic malignancies were more likely to have undetectable NAb and had concordance with NAbts against variants of concern.

Prior SARS-CoV-2 infection boosted NAbTs, including variants of concern. Anti-CD20 treatment was associated with severely diminished NAbTs. Vaccine-induced T-cell responses were detected in 80% of patients, with no differences between vaccines or cancer types.

“Patients with hematologic malignancies had reduced or absent neutralizing activity against variants of concern, whereas patients with solid cancers are comparable to age-matched controls. Previous SARS-CoV-2 infection boosts vaccine-induced responses, lending support for a third dose,” Dr Shepherd concluded.

He added, “Assessing seroconversion may overestimate protection against variants of concern. SARS-CoV-2 specific T-cell responses, including in variants of concern, were seen in the majority of patients with cancer. Ongoing efforts to define precise correlates of protection from breakthrough infections are needed to individualize patient management.”

Disclosures: This research was supported by The Royal Marsden Charity: The National Institute for Health Research Biomedical Research Centre at Royal Marsden Hospital and Institute for Cancer Research. 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.

Reference

Shepherd STC, Fendler A, Au L, et al. Adaptive immunity to SARS-CoV-2 infection and vaccination in cancer patients: The CAPTURE study. Presented at: European Society for Medical Oncology (ESMO) Congress 2021; September 16-21, 2021. Abstract 1557O.

This article originally appeared on Cancer Therapy Advisor