Seroconversion after SARS-CoV-2 mRNA booster vaccine in cancer patients
Ce dossier présente un ensemble d'articles concernant la prise en charge des cancers durant la crise sanitaire liée au COVID-19
In the SINFONIA-V study published in the December 2021 edition of the European Journal of Cancer, we sowed that a 5.8% fraction of patients with solid tumors undergoing anticancer treatment do not achieve seroconversion after primary (2 doses) SARS-CoV-2 mRNA vaccination with BNT162b2 or mRNA-1273 (10/171 individuals); this was significantly different as compared with 0.2% of controls without cancer (p <0.001) . We report here updated data with the analysis of post-booster serological status in these patients (n=10), Interestingly, we found that among 6 evaluable individuals with pre-boosting confirmed seronegativity, 2 (33%) developed anti-spike antibodies after boosting, whereas the remaining showed persistent seronegative status (Table 1). Median follow-up from booster to sampling was 21 days [8–35]. A percentage of rescue by boosting has been demonstrated other studies, but with higher incidence3. Indeed, Ligumsky et al. recently reported that, in patients with solid tumors who lacked immunization after primary SARS-CoV-2 vaccination, seroconversion took place after booster in 85% of 20 initially seronegative patients 3. It should be acknowledged that no conclusions can be drawn based on such limited sample size. However, since the two cohorts were similar in terms of cancer type (100% solid tumors), median primary-to-booster time (200 vs 210 days), proportion receiving anticancer treatment (83% vs 100%), and prevalence of cytotoxic drugs in therapeutic regimens (67% vs 63%), we estimated the probability of seroconversion after booster in the pooled vaccine-refractory solid tumor population. In particular, our study leads to an estimate of 35.7% of seroconversion probability (95% CI 7.7-71.4%), while combined data with Ligumsky as a prior show a final estimate posterior of 73.1% (95% CI 54.9-87.9%). In light of the few data available, such seroconversion probability has a wide uncertainty. However, both studies point in the same direction, showing an additional, although incomplete, efficacy of booster vaccination in this population. Further, such data are consistent with another recently published report in a mixed onco-hematologic population, showing 56% seroconversion 4. In conclusion, even though a variable percentage of patients with solid tumors display immunization after booster despite seronegativity after previous primary vaccine, there is a subpopulation who persistently fails to achieve seroconversion (roughly one third of those who remained seronegative after primary vaccination) . This finding is concerning, as boosters are the leading strategy to enhance immunization. Further investigation is warranted in this population. In particular, pooling data into consortium efforts would allow to better characterize immune responses in patients with cancer, since individual analyses are underpowered to assess patient and treatment subgroups in detail. This would also support the sharing of knowledge and resources on immunological and computational analyses to better dissect this vulnerable population.
European Journal of Cancer , éditorial, 2021