Citrullinated Epitopes Identified on Tumour MHC Class II by Peptide Elution Stimulate Both Regulatory and Th1 Responses and Require Careful Selection for Optimal Anti-Tumour Responses

BackgroundSomatic mutations or post-translational modifications of proteins result in changes that enable immune recognition. One such post-translational modification is citrullination, the conversion of arginine residues to citrulline. Citrullinated peptides are presented on MHC class II (MHCII) via autophagy which is upregulated by cellular stresses such as tumourigenesis.MethodsPeptides were eluted from B16 melanoma expressing HLA-DP4 and analysed by mass spectrometry to profile the presented citrullinated repertoire. Initially, seven of the identified citrullinated peptides were used in combination to vaccinate HLA-DP4 transgenic mice. Immune responses were characterised from the combination and individual vaccines by ex vivo cytokine ELISpot assay and assessed for tumour therapy.ResultsThe combination vaccine induced only weak anti-tumour therapy in the B16cDP4 melanoma model. Immune phenotyping revealed a dominant IFNγ response to citrullinated matrix metalloproteinase-21 peptide (citMMP21) and an IL-10 response to cytochrome p450 peptide (citCp450). Exclusion of the IL-10 inducing citCp450 peptide from the combined vaccine failed to recover a strong anti-tumour response. Single peptide immunisation confirmed the IFNγ response from citMMP21 and the IL-10 response from citCp450 but also showed that citrullinated Glutamate receptor ionotropic (citGRI) peptide stimulated a low avidity IFNγ response. Interestingly, both citMMP21 and citGRI peptides individually, stimulated strong anti-tumour responses that were significantly better than the combined vaccine. In line with the citGRI T cell avidity, it required high dose immunisation to induce an anti-tumour response. This suggests that as the peptides within the combined vaccine had similar binding affinities to MHC-II the combination vaccine may have resulted in lower presentation of each epitope and weak anti-tumour immunity.ConclusionWe demonstrate that tumours present citrullinated peptides that can stimulate Th1 and regulatory responses and that competition likely exists between similar affinity peptides. Characterisation of responses from epitopes identified by peptide elution are necessary to optimise selection for tumour therapy.

Influenza viral particles harboring the SARS-CoV-2 spike RBD as a combination respiratory disease vaccine

Vaccines targeting SARS-CoV-2 have gained emergency FDA approval, however the breadth against emerging variants and the longevity of protection remains unknown. Post-immunization boosting may be required, perhaps on an annual basis if the virus becomes an endemic pathogen. Seasonal influenza virus vaccines are already developed every year, an undertaking made possible by a robust global vaccine production and distribution infrastructure. To create a seasonal combination vaccine targeting influenza viruses and SARS-CoV-2 that is also amenable to frequent reformulation, we have developed a recombinant influenza A virus (IAV) genetic platform that reprograms the virus to package an immunogenic domain of the SARS-CoV-2 spike (S) protein onto IAV particles. Vaccination with this combination vaccine elicits neutralizing antibodies and provides protection from lethal challenge with both pathogens. This technology may allow for leveraging of established influenza vaccine infrastructure to generate a cost-effective and scalable seasonal vaccine solution for both influenza and coronaviruses.

A combined Globo H-OCT4-T7 immunotherapy restrains colorectal tumor growth

Background: Malignant tumors express multiple common markers that might constitute targets for tumor immunotherapy. Methods: Here we performed antigen epitope screening and molecular docking to design a new combination vaccine based on covalently linking Globo H and Oct 4 with a TLR7 agonist. We mainly use flow cytometry to analyze the changes in lymphocyte differentiation after the vaccine is applied. Use Elisa technology to detect the antibodies produced by the vaccine and the changes in lymphokines. In order to supplement the immunological data, RNA sequencing was performed on untreated and vaccine-treated tumors to define the interference of the vaccine on the genome-wide gene expression profile.Results: Our results demonstrated that the Globo H-OCT4-T7 conjugate vaccine effectively induced cellular uptake, maturation and antigen presentation of BMDCs. The combination vaccine enhanced cytokine production, CTLs activity elicited high levels of IgG. Importantly, the tumor immune microenvironment was significantly improved in tumor-bearing mice treated by Globo H-OCT4-T7 conjugate vaccine, demonstrated by increased the ratio of M1 to M2 TAMs, reduced number of Tregs in PBMCs and promoted the infiltration of tumor-specific IFN γ-producing CD8+ T cells. Prophylactic vaccination of Globo H-OCT4-T7 significantly reduced tumor growth by >80 % in both CT26 transplanted mice and in a human PDX mouse model when exposing mice to the combined vaccine compared to control. Our novel, combination vaccine is safe and effective at preventing tumor growth in mice. Conclusions: This combination vaccine is more effective than the single vaccine, and thus has the potential to prevent OCT4 and Globo H from expressing cancer.

Impact of combination MMRV vaccine on first-dose coverage for measles and varicella: a population-based study

Aim Combination vaccines decrease the number of needles required, addressing a common concern of parents. However, some parents are hesitant about combination vaccines and/or want to opt out of certain vaccine components. This study assessed whether introduction of the combination MMRV vaccine influenced coverage levels for measles- and varicella-containing vaccines. Study and methods This was a population-based study of children born in Alberta, Canada between 2006 and 2012. We utilized administrative health data to evaluate coverage for the first dose of measles- and varicella-containing vaccines at the age of 24 months (i.e. between 2008 and 2014) before and after introduction of the combination MMRV vaccine in 2010. Among those who were vaccinated, we assessed whether any children continued to receive separate vaccines after the combination vaccine was introduced. Results Of 308,212 children, 272,345 (88.36%) were vaccinated with measles- and/or varicella-containing vaccines at the age of 24 months. Although coverage for measles-containing vaccines did not change overall between 2008 and 2014, coverage for varicella vaccine increased in the years following the introduction of MMRV. After the combination vaccine introduction, 96.55% of vaccinated children (n = 121,131) received MMRV vaccine. Conclusion Vaccine coverage for varicella increased after the introduction of the combination MMRV vaccine, and there was a narrowing in the gap between MMR and varicella coverage. Very few children received separate vaccines after the introduction of the combination MMRV vaccine. These findings suggest that combination vaccines are acceptable to most parents and increase coverage for varicella in our setting.

1400. Physician Attitudes towards Combination Vaccine Use in Infants up to 24 months of age in the United States (US)

Background Combination vaccines reduce the number of injections and improve the timeliness of vaccination coverage. US Advisory Committee on Immunization Practices (ACIP) recommendations state that combination vaccines are generally preferred over equivalent individual component vaccines. Healthcare providers strongly influence parental decisions about vaccination. We sought a contemporary understanding of physician’s attitudes towards combination vaccine use in infants. Methods We conducted an online survey of US physicians (70 pediatricians and 30 family practitioners) who administer vaccines to infants aged 0-24 months and spend at least 2 days a week providing patient care. Information was collected on attitudes towards combination vaccines and factors that influence the choice of combination vaccine used in clinical practice. Descriptive analyses were performed. Results Physicians (mean age=50.2 years, range 30.0-70.0; 66% white; 37% women) reported a median of 4 injections (range 2-9) as the maximum that parents would accept at a single visit, and 71% routinely explained what combination vaccines are to parents. When deciding which pentavalent vaccine to use, physicians considered how the brand fits into the current vaccine schedule (71%); upfront purchase costs (64%); and availability as a prefilled syringe (61%). The main reasons for using combination vaccines were to reduce the number of injections (96%); ensure the infant is up-to-date with vaccinations (86%); and reduce the pain that the infant experiences with multiple injections (68%). More than half reported that their institution or practice has a program to incentivize infant vaccination according to schedule. If a hexavalent vaccine-based schedule was available, 76% of physicians said they would choose it over their current schedule comprising pentavalent or equivalent component vaccines. Conclusion Choice of pentavalent combination vaccine among pediatricians and family practitioners was largely dependent on convenience and cost-related factors. Over three-quarters would be inclined to use a hexavalent vaccine schedule if available. Disclosures Ya-Ting Chen, PhD, Merck & Co., Inc. (Employee, Shareholder) Xinyi Ng, PhD, Merck & Co., Inc. (Consultant) Tanaz Petigara, PhD, Merck & Co., Inc. (Employee, Shareholder) Jyoti Aggarwal, MHS, Merck & Co., Inc. (Consultant) Jenna Bhaloo, MPH, Merck & Co., Inc. (Consultant) Michelle Goveia, MD, Merck & Co., Inc (Employee, Shareholder) David Johnson, MD, MPH, Sanofi Pasteur (Employee, Shareholder) Gary S. Marshall, MD, GlaxoSmithKline (Consultant, Scientific Research Study Investigator)Merck (Consultant, Scientific Research Study Investigator)Pfizer (Consultant, Scientific Research Study Investigator)Sanofi Pasteur (Consultant, Grant/Research Support, Scientific Research Study Investigator, Honorarium for conference lecture)Seqirus (Consultant, Scientific Research Study Investigator)

1388. DTaP-containing combination vaccines use and adherence to the recommended infant-toddler vaccination series among privately insured children in the US

Background Despite universal recommendation of the 3 + 1 diphtheria, tetanus, and pertussis (DTaP) vaccine series in infants and toddlers, adherence (i.e. coverage and timeliness) remain suboptimal in the US. DTaP-containing combination vaccines are presumed to improve vaccine coverage rates and timeliness, but research on this topic is limited. The purpose of this study was to compare adherence to the recommended infant-toddler vaccination series between recipients of DTaP-containing combination vaccines (i.e. quadrivalent/pentavalent) and stand-alone vaccines (i.e. trivalent). Methods We used the Optum de-identified Clinformatics Data Mart database to create a cohort of children born between 2009 and 2016 with > 24 months of continuous enrollment from birth, and records of > 1 DTaP vaccine receipt. Patients were classified by DTaP-containing vaccine receipt: combination vaccines only, stand-alone vaccines only, or a mixture of both. The primary adherence outcome was completion of the 4-dose series within 20 months of life. We adjusted outcomes for gender, birth year, race, and socioeconomic status via a logistic regression model. Results The cohort contained 200,568 female (48.6%) and 211,882 male (51.4%) children. Of these children, 167,091 received combination vaccines only (40.5%), 61,342 received stand-alone vaccines only (14.9%), and 184,017 received a mixture of both (44.6%). Completion of the 4-dose series was highest among children who received combination vaccines only (75.5%), followed by those who received a mixture of vaccines (72.7%) and those who received stand-alone vaccines only (54.5%). Relative to those who received stand-alone vaccines only, adjusted odds of completion were approximately 2.9 times higher among combination vaccine recipients (odds ratio, OR = 2.93 [95% CI: 2.87, 2.98]) and 2.5 times higher among those who received a mixture of vaccines (OR = 2.54 [2.49, 2.59]). Conclusion DTaP-containing combination vaccine use was associated with significantly greater adherence. Although these results warrant further investigation to better understand the determinants of infant vaccination adherence, such evidence may further support preferential recommendations for combination vaccine use. Disclosures Matthew M. Loiacono, MSc, Sanofi Pasteur (Employee) Vitali Pool, MD, Sanofi Pasteur (Employee) Robertus Van Aalst, MSc, Sanofi Pasteur (Employee)