Yuvaraj, Padhmavathy

Abstract Background: HPV16 (human papillomavirus) is a leading cause of oropharyngeal cancer (OPC) in the US. Antibodies to HPV16 early antigens are detectable in serum samples up to two decades before diagnosis and are potential biomarkers for early detection. In this study, we have developed and compared three custom HPV16 serology platforms for detection of OPC: MSD (Meso Scale Discovery) electrochemiluminescent detection, RAPID ELISA, and a novel semi-quantitative lateral flow assay (LFA) using a custom android application. Methods: For the MSD platform, recombinant HPV 16 antigens (E1, E2, E6, E7) were synthesized in mammalian cells and printed on multiplexed arrays. In RAPID ELISA, GST-tagged antigens (E1, E2, E6, E7) were expressed using mammalian in vitro transcription and translation and bound IgG detected. For the LFA, His-tagged recombinant proteins (HPV16 CE2 184-365aa and HPV16 E7) were synthesized, printed, and antibodies detected with protein G conjugated nanoparticles. Archived serum samples drawn from newly-diagnosed OPC patients (n = 60), with matching saliva samples (n=54, MSD assay only) were obtained from Mayo Clinic. Unmatched controls (n = 46) were obtained from AT Still. For the lateral flow assay, colorimetric image analysis was done using a titration curve of known concentration of monoclonal antibody. We optimized the biomarker panel (E2, E6, and E7 for MSD and ELISA, and for LFA E2, and E7) by using multiparametric analysis and plotting the receiver operating curves to the test performance, and assays were compared using the Cohen’s kappa statistic. Results: At 98% specificity, the MSD HPV16 serologic assay achieved 88% sensitivity, similar to RAPID ELISA, and the LFA assay at 85% sensitivity. The signal intensities for saliva samples were weaker at 24% sensitivity. The Cohen’s kappa value ranged from 0.74 to 0.78 for the comparison between all three assays. There was only one sample among all the cases that was negative by all three serology tests. Conclusion: All three assays have strong concordance for the detection of HPV16 early antigen serology. All the tests can facilitate large scale HPV serology research. Citation Format: Akshansh Kaushik, David Routman, Tej Patel, Joshua Eger, Padhmavathy Yuvaraj, Kathleen R. Bartemes, Marisa D. Griesel, Danielle E. Hunter, Katie Van Abel, Anu Mathew, Mingyue Wang, Leonid Dzantiev, Martin Stengelin, Jacob N. Wohlstadter, Ann Spolarich, Kristina R. Dahlstrom, Jennifer Blain Christen, Erich Sturgis, Karen Anderson. HPV serology for rapid detection of HPV positive oropharyngeal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5099.

Abstract Vaccines to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induce antibody responses against the spike (S) protein. However, the continued emergence of variants such as Omicron (B.1.1.529), with 30 amino acid changes in the S protein, underscores the need to find conserved targets that induce adaptive immunity. Natural infection induces CD8+ T cell activation against the viral proteins S, membrane (M), and nucleocapsid (N) as well as NSPs (non-structural proteins). Our study seeks to find conserved and immunogenic MHC class I epitopes throughout the SARS-CoV-2 peptidome. We used Ensemble MHC, a novel consensus predictive algorithm to select highly immunogenic CD8+ T cell epitopes presented by 52 of the most common HLA-I alleles, covering > 98% of the world’s population. We selected 658 high confidence predicted peptides from the SARS-CoV-2 immunopeptidome and prioritized testing 108 structural epitopes derived from the S, M, N, and E proteins. We collected PBMCs from unexposed, healthy, and convalescent individuals (n=31) covering ~ 85% of HLA alleles in the population, and measured T cell immunity by IFNγ secretion ELISpot and Activation Induced Marker (AIM) flow cytometry. In convalescent individuals, all predicted epitopes tested so far (n=36) were immunogenic (IFNγ response >2 fold than background) but 3/19 tested donors were unreactive. Samples from pre-pandemic (2017–19) unexposed healthy donors are reactive to 42% of tested epitopes, which indicate cross-reactivity to common cold coronaviruses (CCC) and possibly pre-existing protection against SARS-CoV-2. In summary, we have identified 45 highly conserved and immunogenic SARS-CoV-2 CD8+ T cell epitopes as potential targets for vaccine design. Supported by a grant from the Arizona Department of Health Services (AZDHS)

Abstract Introduction: Preclinical data suggests that priming T cell immunity to mutated or overexpressed proteins can induce tumor rejection, and may potentiate the effects of checkpoint blockade. PIK3CA and p53 are the most commonly mutated genes in breast cancer, and are enriched in high-grade and metastatic tumors. Here, we evaluated the immunogenicity of neo-epitopes derived from common PIK3CA and p53 mutations. Methods: We applied a custom informatics pipeline, EpitopeHunter, to predict neo-epitopes (8-11mers) from twelve PIK3CA and ten p53 mutations restricted to thirty-nine MHC class I alleles. We selected high affinity neo-epitopes (IEDB score < 500) with predicted poor binding of the matched wild type epitope. We used the predicted peptides to stimulate PBMC from healthy donors in vitro, and measured T cell immunity by interferon-γ ELISPOT. We compared the T cell specificity of mutant vs wild type epitopes. A positive response to an epitope was defined as a response that met both of the following criteria: 1) net number of spots (after subtracting background) was >5 spots/50,000 cells and 2) net number of spots exceeded the background spots plus two SDs. Results: In total, 1,824 PIK3CA and 1,520 p53 derived peptide sequences were generated. Of these, 42 PIK3CA (2%) and 45 p53 (3%) peptides were predicted to bind to the HLA class I molecules included in our study. Over 90% of the neo-epitopes were 9- and 10-mers, and the predicted neo-epitopes varied across mutations (range 2-10 per mutation). PIK3CAH1047L and p53R248W had the highest number of potential binding neo-epitopes (n=10 each). We successfully generated T cell lines specific for A*0201 PIK3CAH1047L, A*1101 PIK3CAH1047L, A*1101 PIK3CAE542K and A*0201 p53R248W. Conclusions: Common mutations of PIK3CA and p53 can lead to the generation of potential HLA class I restricted neo-epitopes. We identified four immunogenic neo-epitopes, which may serve as candidates for targeted immunotherapy in breast cancer. Citation Format: Chen M, Yuvaraj P, Sharma AA, Narang P, Wilson Sayres MA, Anderson KS. Targeting neo-epitopes from PIK3CA and p53 mutations for immunotherapy of breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-04.