Abstract 1611P
Background
Adults with cancer are susceptible to severe SARS-CoV-2 disease. Emerging data show initial response to COVID-19 vaccination in most patients (pts) with solid cancer, many with haematological (haem) cancer remain vulnerable. Data beyond initial response and regarding effect of booster doses are lacking.
Methods
SerOzNET (ACTRN 12621001004853) is a prospective study of SARS-CoV-2 vaccine response in pts with cancer. Pts are recruited prior to dose 1 and receive standard of care BNT162b2 or ChadOx1-S vaccine. Blood is taken at baseline and after each dose; and analysed for neutralising antibody (Nab) titre, absolute antibody titre (spike & nucleocapsid, Abbott), T cell response and epigenetics. Demographics, diagnosis, treatment, comorbidity and toxicity data are collected. Pts are followed for up to 3 months beyond dose 5 (if eligible).
Results
399 pts were enrolled. Median age was 58. 59% were female. 65% had solid and 35% haem cancer. 353 (89%) had primary vaccination with BNT162b2; 43 (11%) with ChadOx1-S. 203 (51%) received cytotoxic chemotherapy. 95% were ECOG 0-1. NAb results are available for 307 pts post dose 2 and 184 pts post dose 3. Post dose 2, 40% of haem pts and 87% of solid pts responded. Predictors of non-response were ChadOx1-S vaccine (OR 3 p=0.02), haem cancer (OR 14 p<0.001), ECOG ≥1 (OR 2.6 p=0.01) and steroids (OR 5 p=0.01). Age, Charlson comorbidity index, chemotherapy and time post last treatment were not predictive. Post dose 3, 70% of haem pts and 97% of solid pts responded. Only haem cancer remained a significant predictor of non-response (OR 16). Factors associated with non-response amongst haem pts were highly immunosuppressive drugs (e.g. anti CD20, anti Bcl-2), lymphoma (vs. myeloma) and steroids. T cell response (IFN-γ to spike) is available for 62 pts post dose 2 (9 haem, 53 solid). 48 (77%) had detectable response (55% of haem pts, 81% of solid pts). 27/30 (90%) of patients responded post dose 3. Analysis and follow up are ongoing.
Conclusions
An early third vaccine dose is essential to ensure adequate SARS-CoV-2 immunity in pts with cancer. It is especially important for pts with haem cancer, initial ChadOx1-S vaccine, ECOG ≥1 and pts on steroids. Longer follow up will elucidate patterns in T cell response.
Clinical trial identification
ACTRN 12621001004853.
Editorial acknowledgement
Legal entity responsible for the study
Monash Health.
Funding
Cancer Australia, Leukaemia Foundation (Australia), Victorian Cancer Agency (Australia).
Disclosure
C..R. MacIntyre: Financial Interests, Personal and Institutional, Advisory Board: Janssen, AstraZeneca, Seqirus. All other authors have declared no conflicts of interest.