Immunogenicity of BNT162b2 COVID-19 vaccine in melanoma patients receiving immunotherapy

In a recent study under review at the Scientific Reports journal and posted to the Research Square* preprint server, researchers evaluated the immunogenicity of messenger ribonucleic acid (mRNA)-based coronavirus disease 2019 (COVID-19) vaccine BNT162b2 in cancer patients under treatment with immune checkpoint inhibitors (ICIs).

Study: Immunogenicity and safety of the BNT162b2 mRNA Covid-19 vaccine in patients with melanoma treated with immunotherapy. Image Credit: CI Photos / ShutterstockStudy: Immunogenicity and safety of the BNT162b2 mRNA Covid-19 vaccine in patients with melanoma treated with immunotherapy. ​​​​​​​Image Credit: CI Photos / Shutterstock

Background

Some studies have raised concern, although only theoretically, that vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could trigger immune-related adverse events (irAEs) in adult patients with melanomas receiving ICIs. A vaccine's efficacy is determined by investigating how well it prevents disease, whereas immunogenicity measures the type of immune responses the vaccine generates along with their magnitude over time.

In the general population, the Pfizer/BioNTech BNT162b2 vaccine induces highly effective humoral and cell-mediated immune responses, including the production of neutralizing immunoglobulin G (IgG) antibodies and cytokines such as interferon-gamma (IFNγ), tumor necrosis factor-alpha (TNF-α), and interleukin (IL)-2. Additionally, BNT162b2 activates SARS-CoV-2-specific cluster of differentiation (CD)4+ and CD8+ T cells.

Overall, studies exclusively examining COVID-19 vaccine efficacy and safety in patients with cancer and under treatment with immunotherapy are scarce.

About the study

In the current study, researchers enrolled 40 patients who willingly received two 30 mcg doses of the BNT162b2 vaccine intramuscularly at a 21 days interval. The team assessed vaccine immunogenicity at baseline, i.e., from day 0 to four days before the first vaccine dose and between 12 and 21 days after the second dose. They followed the standard venipuncture procedure for the collection of blood samples. 

The researchers tested the patient’s sera for the presence of anti-SARS-CoV-2 spike (S) IgG antibodies using an enzyme-linked immunosorbent assay (ELISA). The cut-off value of 10 arbitrary units (AU)/mL in a real-time reverse-transcription-polymerase chain reaction (RT-PCR) denoted seroconversion.

The team also extracted peripheral blood mononuclear cells (PBMCs) from blood samples. The fluorescence-activated cell sorting (FACS) helped the researchers categorize PBMCs into five lymphoid subtypes - CD4+ T cells, CD25+/- T cells, regulatory T cells (Treg), CD8+ T cells, and programmed cell death protein 1 (PD1)+ cells.

They recorded AEs within seven days after each dose of the vaccine, and follow-up continued for two months. The researchers derived associations between the blood cell populations before and after the vaccination using a paired t-Test. Likewise, they used the Pearson Chi-Square test to find correlations between other categorical variables.

Study findings

Previous studies have shown that the efficacy of the BNT162b2 vaccine in melanoma patients and the general population is comparable in terms of the induced humoral and cellular immune responses, although irAE rates remained low. In fact, the vaccine efficacy of influenza vaccines is reportedly higher in patients treated with ICIs.

In the present study, 97.3% of ICI-treated melanoma patients had a high seroconversion rate. The ICIs are typically non-immunosuppressive. Hence, the factors resulting in low seroconversion rates and antibody titers, such as old age, did not impact vaccine immunogenicity in ICI-treated patients.

There were only two patients on corticosteroids in the study cohort; thus, the authors could not draw conclusive inferences on why these patients with previously diagnosed irAEs had lower antibody titers. Notably, these patients had a non-statistically significant trend of lower antibody titers for irAEs.

Nevertheless, the authors noted no correlation between AE prevalence and vaccine immunogenicity. Moreover, AEs were insignificant and short-lived and ensued more often after the second vaccine dose. The majority of the AEs were either local or low-grade systemic. Accordingly, four of 10 and six of 15 patients after the first and second dose, respectively, exhibited local AEs. After the first vaccine dose, systematic AEs, viz., fever, malaise, and headache, were prevalent in two, three, and one out of 10 patients.

According to the authors, a higher incidence of AEs in cancer patients receiving immunotherapy for a prolonged duration has not been reported previously. However, such prevalence most likely reflects a more robust immune system reaction and cytokine production in cancer patients. In the current study, AEs were more prevalent in patients with a longer duration of immunotherapy, 19.2 months vs. 5.1 months, respectively. Additionally, AEs were more prevalent in younger patients and patients with long-standing disease.

Conclusions

Overall, the present study's findings showed that the BNT162b2 vaccine was highly efficacious and safe in ICI-treated melanoma patients. It also investigated the potential effects of the COVID-19 vaccination on the subpopulations of T cells and myeloid cells, which showed no significant differences before and after vaccination.

In the future, studies should investigate whether the incidence rate of irAEs increases after COVID-19 vaccination. Similarly, the authors could not interpret a significantly higher mean fluorescence intensity (MFI) of PD1+ on CD4+CD25+ T cells before vaccination which warrants further investigation. In this context, studies investigating the influenza vaccine immunogenicity in patients receiving ICI therapy could give some cues.

*Important notice

Research Square publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:
Neha Mathur

Written by

Neha Mathur

Neha is a digital marketing professional based in Gurugram, India. She has a Master’s degree from the University of Rajasthan with a specialization in Biotechnology in 2008. She has experience in pre-clinical research as part of her research project in The Department of Toxicology at the prestigious Central Drug Research Institute (CDRI), Lucknow, India. She also holds a certification in C++ programming.

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