Immunogenicity and the nature of antigens

Impact of influenza vaccination on survival of patients with advanced cancer receiving immune checkpoint inhibitors (INVIDIa-2): final results of the multicentre, prospective, observational study

Background

The prospective multicentre observational INVIDIa-2 study investigated the clinical effectiveness of influenza vaccination in patients with advanced cancer receiving immune checkpoint inhibitors (ICI). In this secondary analysis of the original trial, we aimed to assess the outcomes of patients to immunotherapy based on vaccine administration.

Methods

The original study enrolled patients with advanced solid tumours receiving ICI at 82 Italian Oncology Units from Oct 1, 2019, to Jan 31, 2020. The trial's primary endpoint was the time-adjusted incidence of influenza-like illness (ILI) until April 30, 2020, the results of which were reported previously. Secondary endpoints (data cut-off Jan 31, 2022) included the outcomes of patients to immunotherapy based on vaccine administration, for which the final results are reported herein. A propensity score matching by age, sex, performance status, primary tumour site, comorbidities, and smoking habits was planned for the present analysis. Only patients with available data for these variables were included. The outcomes of interest were overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and disease-control rate (DCR).

Findings

The original study population consisted of 1188 evaluable patients. After a propensity score matching, 1004 patients were considered (502 vaccinated and 502 unvaccinated), and 986 of them were evaluable for overall survival (OS). At the median follow-up of 20 months, the influenza vaccination demonstrated a favourable impact on the outcome receiving ICI in terms of median OS [27.0 months (CI 19.5-34.6) in vaccinated vs. 20.9 months (16.6-25.2) in unvaccinated, p = 0.003], median progression-free survival [12.5 months (CI 10.4-14.6) vs. 9.6 months (CI 7.9-11.4), p = 0.049], and disease-control rate (74.7% vs. 66.5%, p = 0.005). The multivariable analyses confirmed the favourable impact of influenza vaccination in terms of OS (HR 0.75, 95% C.I. 0.62-0.92; p = 0.005) and DCR (OR 1.47, 95% C.I. 1.11-1.96; p = 0.007).

Interpretation

The INVIDIa-2 study results suggest a favourable immunological impact of influenza vaccination on the outcome of cancer patients receiving ICI immunotherapy, further encouraging the vaccine recommendation in this population and supporting translational investigations about the possible synergy between antiviral and antitumour immunity.

Funding

The Federation of Italian Cooperative Oncology Groups (FICOG), Roche S.p.A., and Seqirus.

INfluenza Vaccine Indication During therapy with Immune checkpoint inhibitors: a transversal challenge. The INVIDIa study

AIM

Considering the unmet need for the counseling of cancer patients treated with immune checkpoint inhibitors (CKI) about influenza vaccination, an explorative study was planned to assess flu vaccine efficacy in this population.

METHODS

INVIDIa was a retrospective, multicenter study, enrolling consecutive advanced cancer outpatients receiving CKI during the influenza season 2016-2017.

RESULTS

Of 300 patients, 79 received flu vaccine. The incidence of influenza syndrome was 24.1% among vaccinated, versus 11.8% of controls; odds ratio: 2.4; 95% CI: 1.23-4.59; p = 0.009. The clinical ineffectiveness of vaccine was more pronounced among elderly: 37.8% among vaccinated patients, versus 6.1% of unvaccinated, odds ratio: 9.28; 95% CI: 2.77-31.14; p < 0.0001.

CONCLUSION

Although influenza vaccine may be clinically ineffective in advanced cancer patients receiving CKI, it seems not to negatively impact the efficacy of anticancer therapy.

Relationship of epitope glycosylation and other properties of blood group proteins to the immunogenicity of blood group antigens

BACKGROUND

The intrinsic properties of polypeptide blood group antigens that determine their relative immunogenicities are unknown. Because size, composition, charge, dose, and epitope glycosylation affect the immunogenicity of other polypeptides, we examined whether similar properties were related to the immunogenicity of blood group antigens.

STUDY DESIGN AND METHODS

Amino acid (AA) sequences of antithetical blood group antigens were searched for N- and O-glycosylation sites. Regression analysis was carried out to determine whether blood group protein properties, including total and ectodomain size, red blood cell (RBC) antigen site density, number of mismatched AAs between an antigen and its closest homolog, and differences in mass, charge, and hydrophobicity of the mismatched AAs, were related to immunogenicity.

RESULTS

The immunogenicities of non-RhD polypeptide antigens were directly related to the total and ectodomain sizes of their carrier proteins. A negative power relationship existed between RBC antigen site density and immunogenicity, such that the most immunogenic antigens had the lowest site density. The strong immunogenicity of RhD was related to the number of AA mismatches between RhD and RhCE, to their cumulative hydrophobicity and electrostatic mismatch scores, and the cumulative AA mass difference. No N- or O-glycosylation differences were predicted for antithetical or homologous antigens, other than a previously known N-glycosylation difference between K and k.

CONCLUSION

Epitope glycosylation appeared not to be a determinant of immunogenicity for blood group antigens, except possibly for K. The immunogenicity of blood group antigens was positively related to total and ectodomain sizes of blood group proteins and negatively related to antigen site density. Such findings should be considered hypothesis generating for future, more definitive studies.

Structural and functional impacts of amino acid substitutions that create blood group antigens: implications for immunogenicity

BACKGROUND

The immunogenicities of polypeptide blood group antigens vary widely. One possible determinant of immunogenicity is antigenic foreignness. The goal was to employ alternative ways of assessing foreignness and determine whether foreignness was related to immunogenicity.

STUDY DESIGN AND METHODS

Foreignness was assessed as the extent of protein functional disruption caused by the exofacial amino acid (AA) substitutions that create blood group antigens, using AA substitution prediction algorithms such as Meta-SNP and according to whether those substitutions were radical or conservative.

RESULTS

AA substitutions that create the most immunogenic antigens had the highest Meta-SNP scores, predictive of greater protein structure and function changes. Four of the 11 exofacial AAs that distinguish the most immunogenic antigen, RhD, from RhCE, and substitutions creating four of the five next most immunogenic antigens had the highest Meta-SNP scores (0.293-0.649). Excluding the outlier Jk^a , the mean Meta-SNP score of the four most immunogenic non-RhD antigens (K, Lu^a , E, c) was 3.7-fold higher than the mean of the four least immunogenic (M, Fy^a , C, S), 0.459 versus 0.123 (p = 0.0026). Regression analysis revealed a relationship between immunogenicity and Meta-SNP score (R²  = 0.953). Actual protein functional disruption was predicted for the AA substitution creating the E antigen. An AA cluster at Positions 350, 353, and 354 of RhD was unique, containing radical substitutions according to two classification schemes and relatively high Meta-SNP scores (0.351-0.432).

CONCLUSION

The immunogenicity of blood group antigens was related to the functional disruption caused by the AA substitutions that create the antigens, as measured by Meta-SNP score.