The study reinforces the need to prioritize these patients for vaccination, the authors say.
By Mike Bassett
The Pfizer-BioNTech COVID-19 mRNA vaccine achieved satisfactory levels of seropositivity in patients undergoing cancer treatment, although protection occurred later compared to a healthy population, Israeli researchers found.
Only 29% of cancer patients were seropositive after the first vaccine dose compared to 84% of controls, with median titer scores of 42.3 and 72.0, respectively. However, the seropositivity rate increased to 86% among cancer patients after the second dose, reported Irit Ben-Aharon, MD, PhD, of the Rambam Health Care Campus in Haifa, Israel, and colleagues.
“Although the pattern of immunogenicity was gradual and slower than in the non-cancer population, after the second dose most patients were seropositive and no documented cases of COVID-19 infection were identified,” they wrote in JAMA Oncology . “Our study lends credence to the widely adopted recommendation to prioritize cancer patients for SARS-CoV-2 vaccination.”
Although real-world data have reported on the efficacy and safety of the COVID-19 vaccine in the general population, such data are lacking for cancer patients. The aim of this study was to evaluate the serological status and safety of the Pfizer-BioNTech vaccine in patients with solid tumors who were receiving active cancer treatments.
The study included 232 patients (median age 68 years) who received treatment at the Rambam Health Care Campus and 261 healthy controls of the same age.
The cancer types treated included gastrointestinal (27%), breast (18%), genitourinary (21%), lung (19%), gynecological (5%), head and neck (5%), melanoma (2%), neurological (2%), and sarcoma (1%). The majority of patients (74.1%) had metastatic disease.
The types of treatment included chemotherapy (58%), biological agents (35%) and immunotherapy (36%), and some patients received more than one type of treatment.
When divided by age group, 30% of cancer patients over 60 years of age were seropositive after the first dose compared to 80% of the control group. In the group under 60 years of age, 27% of cancer patients were seropositive compared to 94% of controls.
Ben-Aharon and colleagues observed that breast cancer patients made up 29% of the seronegative group, and 74% of these patients were treated with chemotherapy, using various treatments. "Therefore, we cannot assume that a specific class of drugs can hinder immunogenicity, but rather that lymphosuppressive agents may induce a lack of effective seroconversion," they wrote.
Pain at the injection site was the most frequently reported local reaction (69%). Other local reactions included warmth at the injection site (9%), redness (8%), and swelling (4%). Systemic reactions included fatigue (24%), muscle and joint pain (13%), and headache (10%).
The authors also observed elevated liver enzyme levels of more than 1.5 times compared to baseline levels in 24 patients up to 6 weeks after the first vaccine dose, as well as newly documented regional lymphadenopathy that was observed in 5% of routine CT or PET scans throughout the study period.
"It has been previously demonstrated in vaccination studies of other viruses that the temporary redistribution of lymphocytes from the systemic circulation to lymphoid tissues can be induced by the immune stimulation produced by the vaccine," they noted.
Any intention to forgo a second vaccine dose in some jurisdictions due to vaccine shortages "justifies reassessing unique populations, such as cancer patients, in view of lagging immunogenicity," Ben-Aharon and colleagues concluded.
From: https://www.medpagetoday.com/infectiousdisease/covid19vaccine/93477