ABSTRACT
Background: Adults and childrenwith cancer are susceptible to severe SARS-CoV-2 disease. Vaccination is protective;data beyond initial response and regarding effect of booster doses are lacking in cancer patients. Method(s): The SerOzNET study assesses SARS-CoV-2 vaccine response in haematological and solid cancer patients aged 5 and older. Patients are recruited pre dose 1 and receive standard BNT162b2 (Pfizer) or ChadOx1-S (AstraZeneca) vaccine. Blood is taken at baseline and after each dose. Neutralizing antibody (NAb) titre, absolute antibody titre (Abbott), T cell response (IFN-gamma) and epigenetics are analysed. Clinical data are collected. Patients are followed for up to 3 months beyond dose 5. Result(s): 105 children (64% haem, 36% solid cancers) and 399 adults (35% haem, 65% solid cancers) were enrolled. In adults, NAb response rate increased after dose 3 (Post 2: 40% haem, 87%solid;Post 3:70%haem,97%solid). Post dose 2, predictors of nonresponse were ChadOx1-S vaccine (OR 3 p = .02), haem cancer (OR 14 p < .001), ECOG >=1 (OR 2.6 p = .01) and steroids (OR 5 p = .01). Post dose 3, only haem cancer predicted non-response (OR 16). IFN-gamma response is available for a subset, detectable in 41/90 (46%) postdose 1, 78/96 (81%) post-dose 2 and 35/42 (83%) post-dose 3;without significant difference between haem and solid cancer. In children, NAb response post dose 2 is available for 50 patients. Response rate between haem (19/31, 61%) and solid patients (13/19, 68%) was similar. IFN-gamma response post dose 2 was also similar: (14/22, 63%) vs solid patients (12/14, 85%) (p = .25). Analysis is ongoing. Conclusion(s): Response to two doses of SARS-CoV-2 vaccine is suboptimal in patients with cancer. The third priming dose is integral, with significantly higher response rates observed. 36% of children did not develop neutralizing antibodies post dose 2;subsequent doses are likely to be important for young patients.
ABSTRACT
Background: COVID-19 infection has poor outcomes for patients (pts) with cancer. Understanding vaccine response as a correlate of protection from severe infection is essential to advise pts regarding protective behaviours and optimal vaccine schedule. This Australian cohort is unique due to low rates of COVID-19 exposure at study entry (July-November 2021). and use of a 3 dose schedule. Pts initially received 2 doses of either BNT162b2 (Pf) at a 3 week interval, or ChadOx1-S (AZ) at a 6 week interval, all then received a 3rd dose, either mRNA-1273 (Mod) or Pf after 2-4 months, and finally a 4th dose at an interval of a further 3 months, for a subset. Methods: SerOzNET (ACTRN12621001004853) has enrolled pts with solid and haematological (haem) cancers prior to initial vaccination. Serial blood samples were processed for serum, PBMC and PMN at timepoints: 0, then 3-4 weeks post dose 1 then 2 then 3 then 4 (where administered). We report here neutralizing antibodies (nAb) against wild type (wt) and delta and omicron variants of concern (VOC);quantitative S-protein IgG antibody (Abbott);Tcell correlates measured by levels of interferon-g (IFN g), tumour necrosis factor-a, interleukins (IL-) 2/ 4/5/13;and epigenetic profiling of T cells. Results: The cohort consists of 401 pts with median age 58 (range 18-85);59% female;128 (32%) haem cancers. 377 (94%) are on current or recent (< 12 months) systemic therapy: 162 (43%) chemotherapy, 62 (16%) immunotherapy, 40 (10%) combined chemo/immunotherapy, 113 (29%) hormonal or targeted therapy. 42 (10%) received anti-CD20 therapy < 12 months, 6 (1.4%) had allogeneic stem cell transplant. NAb levels against wt are available for 256 pts post dose 1, 245 pts post dose 2 and 159 pts post dose 3 (will be updated). Response rates post dose were respectively 27%, 77% and 88%. Pts with haem cancer were less likely to respond to vaccination at any time compared to pts with solid cancer (p < 0.001, chi-squared test). After 3 doses, 3.8% of pts with solid cancer and 27.8% with haem cancer lacked NAb. NAb results to VOC delta are available for 92 pts post dose 2: 25/92 (27%) were negative, compared with a non-response rate to wt of 15% at same time in same pts. IFN-γ-Spike response was detectable in 18/31 (58%) and 24/30 (80%) pts post dose 1 and 2 respectively. 101 pts to date have received a 4th dose;data will be available at the meeting, as will epigenetic profiles and detailed clinicopathological correlations. Conclusions: This interim analysis shows that a significant proportion of pts with haem cancers (27.8%) lack protective Sars-CoV-2 antibodies following 3 vaccinations, whereas only 3.8% of solid cancer pts lack detectable response. Results from other B and T cell parameters may also be important in identifying pts less well protected by vaccination. Follow up is ongoing, response rate post 4th dose will be presented at the meeting.