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29-10-2021 | Oncology | News | Article

Active cancer treatment linked to reduced seroconversion rate after COVID-19 vaccination

Hannah Kitt

medwireNews: A prospective cohort study suggests that patients with cancer on active treatment have a higher risk for poor seroconversion after two doses of the Pfizer–BioNTech (BNT162b2) COVID-19 vaccine than those undergoing active surveillance.

Specifically, the risk was increased for people receiving chemotherapy, targeted therapy, or hormone therapy, report Andrea DeCensi (EO Ospedali Galliera, Genova, Italy) and fellow investigators in the European Journal of Cancer.

These findings have “important clinical and public health implications,” highlighting “the need for a third dose and long-term serological testing in non-responders,” they add.

The study included 291 patients who received two doses of the vaccine between March and July 2021 at an Italian hospital. The most common tumor sites were gastrointestinal (34.0%), genitourinary and gynecologic (27.1%), breast (24.8%), and lung (10.3%).

Over a third (39.5%) of the participants were receiving chemotherapy, 24.1% hormone therapy, 7.9% targeted therapy, and 7.2% immune checkpoint inhibitor (ICI) therapy. The remaining 21.3%, who had completed treatment more than 6 months ago and were on active surveillance, served as the control group.

At 42 days after the first vaccine dose, 10.7% of the cohort had an antibody titer reactogenicity below 25 AU/mL, indicating poor seroconversion.

The likelihood of poor seroconversion was higher for people receiving chemotherapy, targeted therapy, or hormone therapy than those on active surveillance, at 13.9%, 21.7%, and 11.4% versus 1.6%, respectively, although the between-group difference for hormone therapy was only borderline statistically significant.

The association between chemotherapy and targeted therapy and poor seroconversion remained significant after adjusting for factors such as age, sex, and tumor site and stage, with respective relative risks (RR) of 8.81 and 16.99 versus active surveillance. And again, the association for hormone therapy was borderline significant, with an RR of 7.91.

There was no significant association for ICI use, with a poor seroconversion rate at day 42 of just 4.8%.

Other factors significantly associated with a poor seroconversion rate included a baseline lymphocyte count below 1 x 109/L versus a count equal to or above this threshold (RR=2.17).

DeCensi et al also looked at the rate of adverse events (AEs) following immunization, with 14.8% of patients reporting multiple events, of which 69.0% were mild and 31.0% were moderate in severity. The most common moderate AE was pain (10.0%), followed by headache and fatigue (6.0% each).

The risk for AEs of any grade was significantly greater among women versus men (odds ratio [OR]=4.41), nonsmokers versus smokers (OR=3.15), and people aged 68 or younger versus older participants (OR=2.64) in a multivariable model adjusted for age, sex, and smoking status.

DeCensi and team therefore suggest that these patients “may benefit from preventive medications such as paracetamol and antihistamines.”

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

29 October 2021: The coronavirus pandemic is affecting all healthcare professionals across the globe. Medicine Matters’ focus, in this difficult time, is the dissemination of the latest data to support you in your research and clinical practice, based on the scientific literature. We will update the information we provide on the site, as the data are published. However, please refer to your own professional and governmental guidelines for the latest guidance in your own country.

Eur J Cancer 2021; doi:10.1016/j.ejca.2021.09.030        

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