Clinical Research Assistant City of Hope Comprehensive Cancer Center Yorba Linda, California, United States
Background: Whereas the short-term effectiveness of COVID-19 vaccination has been widely demonstrated, emerging real-world data suggest that immunity may wane over time (Levin et al. NEJM 2021). The current study examined the long-term efficacy of the COVID-19 vaccination among patients with RCC.
Methods: In this study, patients diagnosed with RCC with no prior COVID-19 vaccination were included. Blood was collected prior to and after one dose of the COVID-19 vaccine at 2- and 6-month timepoints. Antibody titers were assessed using the SCoV-2 Detect IgG ELISA assay and results were reported as immune status ratio (ISR). T-cell receptor (TCR) repertoire sequencing was performed using the MiXCR software (MiLabs) and custom strips were used to assess TCR abundance and homology clustering.
Results: A total of 32 patients provided baseline, 2-, and 6-month blood samples by the 1/30/2022 data cut-off. In this subset, the median age was 62 (range 44-81) years, with the majority being male (71.9%) and white (81.3%). Nearly all (96.9%) patients were receiving systemic treatment, with 58.1% receiving immune checkpoint inhibitors and 41.9% receiving other targeted agents. The most frequently administered vaccines were Pfizer (68.8%) and Moderna (31.2%). The mean ISR values at baseline and 2 months were 0.72±1.67 and 6.51±2.23, respectively. At the 6-month timepoint, mean ISR was 4.93±1.77; this was significantly lower than 2-month antibody titers (p < 0.0001), reflecting a reduction of 24.2%. Further TCR data will be presented at the meeting.
Conclusions: To our knowledge this is the first study to assess the long-term serologic outcomes of COVID-19 vaccination in patients with cancer. Our results suggest waning immunity over time in cancer patients. Strategies to prolong host immunity against SARS COV-2 (e.g., booster vaccination) are warranted.