The Pfizer-BioNTech COVID-19 vaccine induces similar levels of COVID-19 antibodies in patients with solid cancer compared with people without cancer.
Study results recently published in Cancer Discovery indicate that 6 months following the second dose of the Pfizer-BioNTech COVID-19 vaccine, patients with solid tumors and individuals without cancer displayed similar levels of COVID-19 antibodies in their blood. 1
Results from the study showed that 79% of those with solid tumors were seropositive for the antibodies compared with 84% of healthy controls at 6 months after their second dose of the vaccine. However, antibody levels in both groups decreased significantly from the time of vaccination.
“In our study we saw that in all outcomes, including immunogenicity, infectivity rate throughout the 6-month period, and safety, patients with solid tumors depicted a similar trend as the general population,” said lead study author Irit Ben-Aharon, MD, PhD, director of the oncology division at Rambam Health Care Campus in Israel.2
Though the available COVID-19 vaccines have shown high efficacy in the general population, their long-term safety and efficacy among patients with cancer had been underrepresented. Moreover, patients with cancer receiving cytotoxic therapy or immune modifying agents were not able to participate in other vaccine studies, and as such, there remains an unmet need to examine the efficacy of the vaccines in this group.
Although it had been suggested that all patients with cancer were at increased risk for COVID-19 infection, recent studies have shown that outcomes and manifestations differ significantly depending on the malignancy type and treatment. Furthermore, data on vaccine efficacy in patients with cancer have shown similar short-term efficacy and safety among patients with when compared with healthy controls.
In this study, investigators sought to examine the long-term safety and efficacy of the COVID-19 vaccine in this population at 6 months after vaccination.
The study enrolled patients with solid tumors receiving active anti-cancer therapy and followed their progress for 6 months after the administration of the second dose of the vaccine. Patients must have been receiving their cancer therapy throughout 6-month duration, as well.
In the study cohort overall, investigators enrolled 154 patients with solid tumors, in addition to 135 age-matched healthy controls. Of the original cohort, 88 patients were enrolled; 64 who met the inclusion criteria were subsequently added.
In the solid tumor cohort, the median age was 66 years (range, 32-87), and more than half of patients were male (55%). In the control cohort, 56% of individuals were women and the median age was 63 years old (range, 50-87).
Most of the patients with cancer enrolled presented with metastatic disease (84%), and the most common cancer types were gastrointestinal (36%), lung (23%), breast (17%), and genitourinary cancers (11%). Moreover, the most common anti-cancer treatment among patients was chemotherapy (62%), followed by biological agents (36%) and immunotherapy (30%).
Additional data showed that chemotherapy was more highly associated with seronegative serologic status vs other treatment modalities (27% vs 10%; odds ratio [OR], 0.31; P = .02), and women were more likely to be seropositive than men (93% vs 75%; OR, 0.21; P = .004).
Furthermore, there was 1 documented case of severe COVID-19 infection that required hospitalization in the cohort of patients with cancer.
In terms of safety, elevation of liver enzyme levels was reported in 10% of patients with cancer up to 6 weeks after receiving the first dose of the vaccine. Moreover, newly documented regional lymphadenopathy was reported on 5% of CT/PET scans. However, all adverse effects were resolved in all patients throughout the course of the study period.
Additionally, the vaccination led to anti-cancer treatment delays for 6% of patients with cancer, all of whom were receiving chemotherapy. Delays were most commonly due to neutropenia, mild thrombocytopenia, and neutropenia with herpes labialis.
“Our study indicates that the pattern of immunogenicity and efficacy of the [Pfizer-BioNTech COVID-19 vaccine] in patients with solid tumors on active intravenous anti-cancer treatment 6-months post vaccination resemble the pattern of the general population,” the study authors concluded. “Former subtle differences which were evident between the 2 cohorts shortly after vaccination disappeared throughout time. Nonetheless, due to uncertainty of the extended efficacy of the vaccine in the general population and recent reports on rising infection rates among vaccinated individuals, adherence to health care risk reduction recommendations is cardinal.”