Author: By Lynda Williams, Senior medwireNews Reporter
medwireNews: Cancer patients are less likely than healthy individuals to achieve an antibody response to their first BNT162b2 vaccine and should be prioritised to receive their second dose within 21 days, indicate two sets of study findings from the UK and France.
Both studies assessed seroconversion to the SARS-CoV-2 spike (S) protein in patients who had not previously been exposed to the virus.
Sheeba Irshad, from King’s College London, and co-workers recruited 151 patients with solid or haematological tumours and 54 healthy controls who received their first BNT162b2 vaccination from December 2020.
Approximately 21 days after vaccination, 38% of the 56 patients with solid cancer and 18% of the 44 haematological cancer patients had a positive anti-S immunoglobulin (Ig)G titre compared with 94% of 34 healthy individuals.
And analysis of IgG titres suggested that “the main difference between healthy controls and patients with cancer was a failure to produce a response, rather than the magnitude of the response”, the investigators remark in The Lancet Oncology.
Among patients who received a second dose on day 21, assessment 2 weeks later showed that 95% of the 19 solid cancer patients and 60% of five haematological cancer patients were seropositive, whereas among patients who did not receive the 21-day booster, just 30% of 33 solid tumour patients and 11% of 36 haematological cancer patients were seropositive.
Seropositive rates at this time among the 12 healthy individuals with and the 21 without a second booster were 100% and 86%, respectively.
The significant boost in response “included seroconversion of patients with advanced-stage cancers or receiving treatments, or both, that can hinder immune responsiveness”, the authors comment, but they admit that the patient numbers in the analysis for haematological cancer response were “insufficient to assess the impact of boosting.”
Jérôme Barrière, from Clinique Saint Jean in Cagnes-Sur-Mer, and co-workers describe their findings for 122 patients with solid cancer – the majority (86%) of whom were undergoing chemotherapy with or without targeted therapy – and 29 healthy volunteers.
In a letter to the Annals of Oncology, the team reports that 3–4 weeks after a first BNT162b2 vaccination in early 2021, 47.5% of cancer patients were seropositive, rising to 95.2% at 3–4 weeks after their booster dose.
All the healthy volunteers were seropositive after both their first and second vaccination, the researchers say.
Although both patients and healthy individuals had a significant increase in their median anti-S antibody levels after their second vaccination, the titre remained significantly lower in the patient group at both timepoints.
“Considering the high proportion of weakly- or unresponsive patients in this setting after a single dose, patients should be informed of the need to maintain strict social protection measures for at least 6-8 weeks after the first dose of the vaccine and we strongly recommend not to shift the booster dose schedule in patients under [chemotherapy]”, advise Jérôme Barrière and co-authors.
And Sheeba Irshad and colleagues emphasize that the lack of protection after a single dose “is of particular concern given our and others’ observations that immunocompromised patients have a higher incidence of harbouring persistent SARS-CoV-2 infections, possibly providing an important reservoir for the emergence of novel viral variants.”
They add that the BNT162b2 vaccine was “well tolerated” – neither study reported serious adverse events with vaccination.
Monin L, Laing AG, Muñoz-Ruiz M, et al. Safety and immunogenicity of one versus two doses of the COVID-19 vaccine BNT162b2 for patients with cancer: interim analysis of a prospective observational study. Lancet Oncol; Advance online publication 27 April 2021. DOI: 10.1016/S1470-2045(21)00213-8
Barrière J, Chamorey E, Adjtoutah Z, et al. Impaired immunogenicity of BNT162b2 anti SARS-CoV-2 vaccine in patients treated for solid tumors. Ann Oncol; Advance online publication 27 April 2021. DOI: 10.1016/j.annonc.2021.04.019
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