Immunogenicity and Safety of COVID-19 Vaccine BNT162b2 for Patients with Solid Cancer: A Large Cohort Prospective Study from a Single Institution

Patients with cancer (CP) are at higher risk of severe COVID-19 manifestations (1) and thus have been considered as a high-priority group for COVID-19 vaccination (2, 3), although the evidence regarding the immunogenicity and safety of COVID-19 vaccines for this frail population is very limited. In fact, in the phase III trial of the BNT162b2 vaccine (4), CP were mostly excluded and only small cohort studies enrolling CP have been available to date (5–9).

Regina Elena National Cancer Institute was the first Italian institution to start vaccination of CP afferent to its units on March 2021. Early results of the trial regarding the effectiveness of BNT162b2 among the health care workers (HCW) employed in the hospital, showed that 99.5% of participants developed a humoral immune response (10). Herein we report on the immunogenicity and safety of the BNT162b2 vaccine in the large cohort of patients affected by solid tumors, included in the ongoing study.

This prospective cohort study included CP afferent to Medical Oncology 1 of Regina-Elena National Cancer Institute in Rome who were eligible for COVID-19 vaccination, according to the recommendation of the Minister of Health (11), if they were receiving systemic immunosuppressive antitumor treatment or received it in the last 6 months (since the start of the study) or had an uncontrolled advanced disease. A cohort of vaccinated HCW employed at the same institution was considered as a control group.

All participants enrolled received two 30 μg/0.3 mL doses of BNT162b2 (Comirnaty, BioNTech/Pfizer), administered intramuscularly 21 days apart, without delaying the prefixed schedule of the active anticancer therapy.

Written informed consent was obtained by all the participants before any study procedures. The study protocol was reviewed and approved by the local Institutional Review Board and Ethical Committee (protocol RS1463/21), registered to a Clinical Trial registry ISRCTN55371988, and conducted according to the principles of the Declaration of Helsinki and EU General Data Protection Regulation (GDPR, 25.05.18). Patients' data were anonymized before analysis.

Blood samples for the assessment of IgG antibodies (Ab) against S1/S2 antigens of SARS-CoV-2 (anti-S IgG) were collected prevaccination [timepoint (TP) 0], and at 3 (TP1) and 7 weeks (TP2) after the first dose. Neutralizing Abs (NAb) were also measured at TP2.

Quantitative measurement of anti-S IgG Abs was performed using the Liason chemiluminescent immunoassay (DiaSorin) according to the manufacturer's instruction. The concentrations of both 15 and 80 AU/mL were adopted as the cutoffs to define the response because, as reported in the manufactory study, these levels were correlated with the presence of NAbs and used to select donors of hyperimmune plasma, respectively (12). The ACE2-RBD Neutralization Assay (DIA.PRO) was used at TP2 to detect NAbs. According to the manufacturer's instruction, development of a Co/S > 10 was adopted to define responders.

Serial nasopharyngeal SARS-CoV-2 RT-PCR swab-tests (Anatolia GeneWorks) were performed at TP0, TP1, and subsequently at the time of each access to Hospital for anticancer treatment or however if symptoms possibly related to COVID-19 occurred.

The primary endpoint was the evaluation of humoral immunity to SARS-CoV-2 Spike (S) protein.

The serologic response rate (RR) and serologic protection rate were defined as the proportion of responders according to the fixed cutoffs of anti-S IgG and NAb titres, respectively. Geometric mean concentration (GMC) was also used to report the anti-S IgG titre.

The safety of the vaccine in CP was assessed until one month after the boost by using a multiple-item questionnaire or telephone consultations. Adverse events (AE) were graded according to a patient-reported scale (very mild/mild/moderate/severe). The differences between groups and the associations of variables with outcomes were evaluated by Student t test, χ², and Spearman correlation, as appropriate. Odds Ratios (OR) were estimated with a logistic regression model. A multivariate analysis approach using Wald-statistic was also adopted. When comparing outcomes between the cohorts, a propensity score approach was used to match the two groups according to sex and age. Statistical analysis was done using SPSS Statistics software v.21 and R v.4.0.5. P < 0.05 was considered statistically significant.

From March 1, 2021 to March 20, 2021, the BNT162b2 was proposed to 914 CP, of whom 816 (89.3%) accepted to get vaccinated (13) and 786 of 816 (96.3%) received both fixed doses (Fig. 1). Characteristics of patients are reported in Table 1. The median age was 62 years (range, 21–97). Breast cancer [250 (30.6%)] and lung cancer [168 (20.6%)], were the most common tumor subtypes. Most of the patients [738 (90.4%)] were under active antitumor treatment, and chemotherapy (alone or with other agents) represented the most used therapy [295 (36.1%)]. Chronic steroid therapy, defined as the daily assumption of glucocorticoids at any dosage started at least 30 days before the vaccination, was reported in 103 (12.6%) patients.

Of the 781 CP (95.7%) tested for seroprevalence at baseline, 29 (3.7%) had a value of anti-S IgG >15 AU/mL, of whom 11 had a known history of COVID-19. The serologic RR significantly increased from TP0 (2.6%) to TP1 (59.8%; P < 0.0001) and from TP1 to TP2 (59.8% vs. 94.2%; P < 0.0001), using 15 AU/mL as cutoff (Fig. 2A). Adopting the higher cutoff of 80 AU/mL, the RR significantly increased from 14.2% after the first dose to 86% following the booster (P < 0.0001; Fig. 2B). There was also a statistically significant increase of anti-S IgG across time-points for both absolute concentration (Fig. 3A) and GMC (Supplementary Table S1). Only 42 (5.8%) patients were non-responders (IgG <15 AU/mL) after the booster. The median age was 62 (33–80) years, males were 18 (42.9%), and Eastern Coopeartive Oncology Group performance status (ECOG PS) was 0 in 32 (73.8%) nonresponder patients. Breast (38.1%) and lung cancer (14.3%) were the most common tumors among nonresponders. Active chemotherapy and chronic steroid use were reported in 31 (73.8%) and 17 (40.5%) of nonresponders, respectively.

Univariate and multivariate analyses of serologic RR in the whole CP cohort according to clinical characteristics were reported in Table 2 and Supplementary Table S2. Chronic use of steroids and chemotherapy-based treatment resulted as independent predictors of low RR both at TP1 and TP2, adopting 15 UI/mL as the cutoff (Table 2), and at TP2, only using 80 AU/mL as threshold (Supplementary Table S2). Multivariate analysis also confirmed the statistically significant association between the incidence of any AEs after the booster and higher RR, irrespective of the cutoffs adopted (Table 2; Supplementary Table S2).

In HCW control group, evaluable patients were 274 at TP0, 271 (98.9%) at TP1, and 251 (91.6%) at TP2. The median age was 47 years (range, 21–69) and females were 158 (57.6%). The proportion of responders significantly increased from TP0 (2.9%) to TP1 (93.7%) and was quite similar between TP1 and TP2 adopting 15 AU/mL as cutoff (93.7% vs. 100%; Fig. 2A), in contrast to the statistically significant increase of serologic RR from TP1 (33.6%) to TP2 (99.2%), observed with 80 UI/mL as threshold for response (Fig. 2B). Also in the HCW, both the anti-S-IgG GMC and the absolute value significantly increased across the different TPs (P < 0001; Supplementary Table S1; Fig. 3A).

The comparison between the matched cohorts revealed a lower serologic RR in CP than in HCW both at TP1 (61.2% vs. 93.2%, P < 0.0001) and at TP2 (93.3% vs. 100%, P < 0.0001; Table 3). Similar results were also found using 80 AU/mL as the threshold for the comparison (Table 3). The GMC of IgG (Table 3), as well as the absolute concentration (Fig. 3B) of IgG, were significantly lower in CP than in HCW after the first dose (at TP1). No significant differences of IgG titres were found between the two cohorts after the second dose.

According to NAbs levels, responders (Co/S > 10) were 240/301 (79.7%) in CP cohort and 131/175 (74.9%) in HCW group. Comparing the two matched cohorts, a trend of higher serologic protection rate was found in CP group (83%) than in HCW (71.9%; P = 0.05). The titre of NAbs and anti-S IgG were significantly associated in the whole CP cohort (Spearman rho = 0.79; P < 0.0001; Supplementary Fig. S1).

The safety profile was detailed in Supplementary Tables S3 and S4. AE occurred in 359 (44%) and in 301 (38.3%) patients after the first and second dose, respectively. Severe-grade toxicity was reported in 29 (3.3%) patients after the first inoculum and in 10 (1.4%) patients after the booster.

After the first dose, local side effects were observed in 29.8% of cases. Among the systemic effects, fatigue (8.3%), headaches (3.9%), and arthralgia/myalgia (3.7%) were the most common. One patient experienced tongue edema associated with dyspnea after 2 hours of vaccine administration, followed by a spontaneous resolution. One sudden death occurred 5 days after vaccine administration in a hospitalized patient who received active chemotherapy for advanced bladder cancer. The postmortem examination revealed pulmonary embolism.

After the second dose, the most common AE reported was fever (14.1%) followed by local reactions (12.6%), fatigue (10.4%), and arthralgia/myalgia (5.2%).

Overall, five cases of asymptomatic and laboratory-confirmed COVID-19 were recorded, three after the first inoculation and two after the booster. SARS-CoV-2 variants B.1.1.7 (UK) and P.1 (Brazil) were identified by viral genome sequencing in 2 and 1 patients, respectively.

We found that the BNT162b2 vaccine stimulated antigen-specific humoral response compared with baseline levels, and generally was well tolerated in a large cohort of CP. However, the serologic RR was lower among CP than in HCW, with the largest difference observed after the first dose, while the level of anti-S IgG reached after the second dose was similar between the two groups. No additional safety alarms arose among CP, including patients who were on active treatment, such as immunotherapy, as reported previously (14). Interestingly, the occurring of any AE after the booster was associated with a higher likelihood of serologic response, in line with previous findings regarding inactivated vaccines, for which high levels of inflammatory cytokines after administration were associated with stronger immune responses and systemic side effects (15).

To our knowledge, this is the study on COVID-19 vaccination in CP with the largest sample size which gives reliability to the results and also allows for a real-world assessment of the vaccine effects in this frail population. Other available studies focused on CP are strongly limited by the small sample size (5–9).

In our study, CP showed a serologic RR of 59.8% and a low titre of antibodies after a single dose (21.02 AU/mL), which largely increased only after the booster, in contrast with HCW, who reached a good level of immunization just after a single dose. Accordingly, in the UK observational study (5), including 56 CP, only 38% of CP versus 94% of HCW (34 subjects) had an immune response with a single inoculum. On the basis of these findings, the second dose is fundamental to develop an adequate immunization specifically in CP and thus any delay of second dose administration, as authorized by the Italian Government on May 5, 2021, could have been dangerous for this frail population. The studies from Israel (6) and United States (8) evaluated the serologic response only after the two doses of COVID-19 vaccine, thus data after a single dose are lacking. Furthermore, these studies are also characterized by limited cohorts of CP (102 and 134 patients, respectively), which were compared with a smaller control group of vaccinated family members/caregivers or patients without cancer, without the adoption of any statistical approach to control the effect of potential confounding clinical factors. In the current study, we used the propensity score analysis for sex and age to minimize the risk of bias potentially related to these clinical features in the cross-comparison between the study cohorts.

Interestingly, we found that active chemotherapy and prolonged use of steroids were strong predictors of lower serologic response due to their immunosuppressive effects. The potential negative influence of active chemotherapy on the response to COVID-19 vaccination could be conceivable because it was previously reported, also for other vaccines, reduced immunogenicity in patients affected by hematologic malignancies and undergoing treatment with intense immunosuppression, such as recipients of allogeneic hematopoietic stem cell transplantation (HSCT), CAR-T, or other B-cell depleting agents (16, 17). Nevertheless, our study could be considered as one of the few studies to report on the negative role of glucocorticoids on COVID-19 mRNA vaccine efficacy in CP, which was previously demonstrated only for patients affected by chronic inflammatory diseases requiring chronic treatment with steroids (18).

Another recent Israeli study (9) evaluated the serologic response in 232 CP under active treatment and 264 age-matched HCW, using the same assay and cutoff (15 AU/mL) employed in our analysis. Similar to our study, they found, in addition to the reaching of a relevant proportion of responders only after the second dose, a lower rate of serologic positive status in patients under chemotherapy. However, in contrast to the current study, no information was reported on the use of steroids and the serologic status of participants was not assessed before vaccination, introducing the risk of a not negligible bias in the assessment of subsequent serologic response.

Regarding the evaluation of NAbs, we surprisingly found a higher proportion of responders in CP than in HCW, although the statistical significance was not reached. It is very difficult to understand the biological basis of this observation also because the NAbs have not been extensively studied in CP, so far. Although the role of NAbs to SARS-CoV-2 needs to be better clarified, measurement of serum neutralizing activity is commonly accepted to be a functional biomarker of in vivo disease protection (19). This assumption was also confirmed in our study, considering the high proportion of responders with NAbs and the very low prevalence of overall laboratory-confirmed COVID-19 cases (5/816 patients, 0.61%) found in CP cohort. Moreover, the strong correlation found between the titre of binding Abs and the NAbs level, if confirmed in further studies, would allow for a wider use of anti-S IgG as a surrogate of NAbs, saving the cost of the more sophisticated and expensive neutralization assays.

Despite the relevant points of strength such as the large sample size, the prospective design and comparison with an age- and sex-matched control group, our study has some flaws.

At this interim analysis, T cells' response to the vaccine has not been yet evaluated. Furthermore, the short duration of follow-up (1 month after the booster) does not reveal potential issues on the long-term safety and immunogenicity of the vaccine. Cutoffs of antibody titres to evaluate serologic response were adopted on the basis of the results of a study promoted by the manufacturer (12), which need to be confirmed by further trials. The mono-institutional design of the study requires external validation of the results to minimize the risk of bias. Finally, a right control group including unvaccinated CP is lacking. However, the study is still ongoing allowing for enlargement of specific study subgroups and for the evaluation of T-cell response and serologic response (IgG and NAbs) in a long-term period to address the interesting question of the duration of immunogenicity in CP under active treatment.

In conclusion, BNT162b2 seems to assure serologic immunization without clinically significant toxicity also in CP population, characterized by a wide range of tumor subtypes and anticancer treatments. In absence of randomized trials on vaccine immunogenicity including this frail population, large observational studies, like the current trial, may provide a further scientific evidence for a strong recommendation of the vaccine administration in the vulnerable CP (20).

V. Di Noia reports grants from Roche, as well as personal fees from AstraZeneca, MSD, BMS, Istituto Gentili, and Boehringer Ingelheim outside the submitted work. F. Cognetti reports personal fees from GSK, Roche, AstraZeneca, Lilly, Novartis, Amgen, Pfizer, MSD, BMS, and Astellas outside the submitted work. No disclosures were reported by the other authors.

V. Di Noia: Conceptualization, data curation, supervision, investigation, methodology, writing–original draft, project administration, writing–review and editing. F. Pimpinelli: Resources, formal analysis, funding acquisition. D. Renna: Conceptualization, data curation, formal analysis, investigation, visualization, methodology. V. Barberi: Data curation, investigation, methodology, writing–review and editing. M.T. Maccallini: Data curation, investigation. L. Gariazzo: Data curation, investigation. M. Pontone: Resources, formal analysis. A. Monti: Resources, formal analysis. F. Campo: Conceptualization, data curation, investigation. E. Taraborelli: Investigation. M. Di Santo: Investigation. F. Petrone: Resources. C. Mandoj: Formal analysis, investigation, methodology. V. Ferraresi: Conceptualization, investigation. G. Ferretti: Formal analysis, investigation, writing–original draft, writing–review and editing. P. Carlini: Formal analysis, investigation, writing–original draft, writing–review and editing. O. Di Bella: Supervision. L. Conti: Resources, formal analysis, investigation. A.M. La Malfa: Resources, formal analysis, investigation. R. Pellini: Resources, investigation, project administration. D. Bracco: Supervision, project administration. D. Giannarelli: Data curation, software, formal analysis, supervision, methodology. A. Morrone: Conceptualization, supervision, funding acquisition, project administration. F. Cognetti: Conceptualization, resources, data curation, supervision, funding acquisition, validation, investigation, visualization, methodology, writing–original draft, project administration, writing–review and editing.

We thank medical oncologists (Fabiana Letizia Cecere, Elvira Colella, Consuelo D'Ambrosio, Emanuela Dell'Aquila, Simona Gasparro, Paola Malaguti, Domenicangela Pellegrini, Michelangelo Russillo, Antonella Savarese, Sabrina Vari, Massimo Zeuli, Maria Bassanelli), residents (Mattia Di Civita, Federica Riva), research nurses (Stefano Pacilli, Giulia Costantini), nurses of Medical Oncology 1 Unit, hospital pharmacists, medical direction member (Ludovica Malaguti Aliberti), and data managers (Elisabetta Bozzoli, Alessandra Zambardi, Viviana Cangiano, Barbara Conforti) of IRCCS Regina Elena National Cancer Institute in Rome, Italy for their commitment to the COVID-19 vaccination campaign for patients with cancer. We thank the patients afferent to our Unit and their families.

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