Antibody response to SARS-CoV-2 WT and Omicron BA.4/5 of inactivated COVID-19 vaccine in patients with lung cancer after second and booster immunization

Since SARS-CoV-2 spread all over the world, patients with lung cancer (LCs) had an estimated case fatality rate of more than 30%, compared with 0.7% to 8.0% in general population [1]. As the median age of LCs diagnosis was 70 years, and immune dysregulation because of the need to receive anticancer therapy for the remainder of their lives [2, 3], antibody responses to two-dose inactivated vaccine in LCs were low [4]. In addition, blunted humoral responses to two-dose and booster mRNA vaccination were found in LCs [5, 6]. However, scarcely anything was known about the magnitude, quantity and duration of antibody response of booster dose of inactivated vaccine in LCs.

In addition, the Omicron variant harboring 30–40 mutations in the viral spike protein produced high immune evasion [7]. Homologous inactivated vaccine BBIBP-CorV booster improved neutralizing activity against Omicron variant in general population [8]. However, inactivated vaccine-induced immune responses to current predominant variants BA.5 in LCs remain unknown.

To address these key issues, we studied the humoral responses to inactivated vaccines in 260 LCs (Table 1), 140 age, sex and vaccination period matched healthy controls (HCs) after the second and booster vaccines (Additional file 1: Methods, Additional file 2: Table S1). Total antibodies against SARS-CoV-2 were 3.5-fold higher in HCs than LCs after the second dose. It showed > threefold increment post-booster vaccine (P < 0.05) than the second in LCs. A durability of total antibodies was found (14–90 days vs. > 180 days, P = 0.1890) (Fig. 1A). IgG anti-SARS-CoV-2 spike RBD antibodies results supporting increased response post-booster shot with a 2.8-fold increment in 14–90 days (P = 0.0422) in LCs, but it decreased faster than HCs and the result showed it was 3.8-fold higher in HCs than LCs after 180 days post-booster vaccine (P = 0.0003) (Fig. 1B). We further examined the neutralizing antibody (NAb) against the SARS-CoV-2 WT and Omicron. Overall, booster recipients exhibited increased NAb to WT in LCs, although it was lower than HCs. The waning tendency of NAb against WT and BA.4/5 post-third dose was found in both LCs and HCs (Fig. 1C, D; Additional file 2: Table S2), which had also been confirmed in other 40 LCs with serial samples (Additional file 2: Table S3, Additional file 3: Fig. S1). By comparison, ancestral SARS-CoV-2 neutralization ability was 1.3–2.8-fold higher compared with Omicron (P < 0.05) in LCs (Additional file 4: Fig. S2 and Additional file 2: Table S4).

Next, we explored factors influenced the humoral response in these 260 LCs with single sampling and performed logistical analysis in 144 LCs received booster vaccines. Consisting with Ramasamy’s report in healthy people [9], the age did not influence expression of binding antibody in LCs (Fig. 1E). By contrast, in line with that NAb response to mRNA vaccination was age-dependent decline [2, 10], we did observe a statistically significant correlation between age and NAb toward WT in LCs and predictive value of LCs aged over 65 for lack of immunization (OR = 0.322, 95% CI 0.134–0.773, P = 0.0112) (Fig. 1E, Additional file 2: Table S5 and Table S7). This finding suggested that the elderly patients should be given more attention while planning vaccination programs.

Moreover, our results suggested undergoing various anticancer therapies influenced the antibody response of post-booster vaccine. LCs received radiotherapy generated lower level of total antibodies than other therapeutic strategies post-booster inactivated vaccines. The IgG anti-RBD antibodies titer, NAbs against WT and Omicron BA.4/5 were significantly lower in patients receiving various therapies than those without (Fig. 1F, Additional file 2: Table S6). Notably, the undergoing radiotherapy was an risk factor for immunization of NAb toward WT (OR = 0.082, 95% CI 0.011–0.617, P = 0.0151) in LCs (Additional file 2: Table S7). This reduced humoral response may be due to the immunosuppressive conditions and lymphocytes decrement induced by chemotherapy or radiotherapy [11]. Further research revealed that the lymphocyte counts were indeed significant lower in the LCs (1.56[1.213–2.018]) than HC (1.76[1.428–2.198]) (P = 0.0017) (Additional file 5: Fig. S3). In addition, the lymphocyte counts showed a positive correlation with the IgG anti-RBD antibodies (P = 0.0266) and Omicron BA.4/5 in LCs (P = 0.0339). The lower immunization may be explained by lower number total B cells, CD4⁺T cells and CD8⁺T counts in LCs as their correlation to the humoral response (Additional file 6: Fig. S4).

Overall, our study revealed strengthened humoral responses post-booster vaccine among LCs, albeit lower than HCs. However, the booster dose failed to establish a potent and durable antibody response for Omicron BA.4/5, which gives rise to the risk of breakthrough infections of Omicron variants, especially in those old and undergoing anticancer therapies. Given the lower antibodies in LCs receiving various active anticancer therapies, further studies are needed to determine whether increased dosage, mixing vaccine types or additional doses enhance immunogenicity.