No abstract

Cancer treatment with immune checkpoint blockade (ICB) often induces immune-related adverse events (irAEs). We hypothesized that proteins coexpressed in tumors and normal cells could be antigenic targets in irAEs and herein described DITAS (discovery of tumor-associated self-antigens) for their identification. DITAS computed transcriptional similarity between lung tumors and healthy lung tissue based on single-sample gene set enrichment analysis. This identified 10 lung tissue–specific genes highly expressed in the lung tumors. Computational analysis was combined with functional T cell assays and single-cell RNA sequencing of the antigen-specific T cells to validate the lung tumor self-antigens. In patients with non–small cell lung cancer (NSCLC) treated with ICB, napsin A was a self-antigen that elicited strong CD8 + T cell responses, with ICB responders harboring higher frequencies of these CD8 + T cells compared with nonresponders. Human leukocyte antigen (HLA) class I ligands derived from napsin A were present in human lung tumors and in nontumor lung tissues, and napsin A tetramers confirmed the presence of napsin A–specific CD8 + T cells in blood and tumors of patients with NSCLC. Napsin A–specific T cell clonotypes were enriched in lung tumors and ICB-induced inflammatory lung lesions and could kill immortalized HLA-matched NSCLC cells ex vivo. Single-cell RNA sequencing revealed that these T cell clonotypes expressed proinflammatory cytokines and cytotoxic markers. Thus, DITAS successfully identified self-antigens, including napsin A, that likely mediate effective antitumor T cell responses in NSCLC and may simultaneously underpin lung irAEs.

Biomarkers for predicting response to anti-programmed death-1 (PD-1) immune checkpoint blockade (ICB) in non-small cell lung cancer (NSCLC) remain in demand. Since anti-tumor immune activation is a process, early dynamic changes of the acute-phase reactant C reactive protein (CRP) may serve as a predictive on-treatment biomarker. In a retrospective (N=105) and prospective (N=108) ICB-treated NSCLC cohort, early CRP kinetics were stratified after the start of immunotherapy until weeks 4, 6, and 12 as follows: an early doubling of baseline CRP followed by a drop below baseline (CRP flare-responder), a drop of at least 30% below baseline without prior flare (CRP responders), or those who remained as CRP non-responders. In our study, we observed characteristic longitudinal changes of serum CRP concentration after the initiation of ICB. In the prospective cohort, N=40 patients were defined as CRP non-responders, N=39 as CRP responders, and N=29 as CRP flare-responders with a median progression-free survival (PFS) of 2.4, 8.1, and 14.3 months, respectively, and overall survival (OS) of 6.6, 18.6, and 32.9 months (both log-rank p<0.001). Of note, CRP flare-responses, characterized by a sharp on-treatment CRP increase in the first weeks after therapy initiation, followed by a decrease of CRP serum level below baseline, predict ICB response as early as 4 weeks after therapy initiation. Of note, early CRP kinetics showed no predictive value for chemoimmunotherapy or when steroids were administered concurrently. On-treatment CRP kinetics had a predictive value for both major histological NSCLC subtypes, adenocarcinoma and squamous cell carcinoma. The results were verified in an independent retrospective cohort of 105 patients. In conclusion, CRP flare predicted anti-PD-1 monotherapy response and survival in two independent cohorts including a total of 213 patients with NSCLC, regardless of histology. Due to its wide clinical availability, early CRP kinetics could become an easily determined, cost-efficient, and non-invasive biomarker to predict response to checkpoint inhibitors in NSCLC within the first month.

No abstract

Complications affecting the lung are hallmarks of severe coronavirus disease 2019 (COVID-19). While there is evidence for autoimmunity in severe COVID-19, the exact mechanisms remain unknown. Here, we established a prospective observational cohort to study lung specific autoantibodies (auto-Abs). Incubation of plasma from severe COVID-19 patients with healthy human lung tissue revealed the presence of IgA antibodies binding to surfactant-producing pneumocytes. Enzyme-linked immunosorbent assays (ELISA) and protein pull-downs using porcine surfactant confirmed the presence of auto-Abs binding to surfactant proteins in severe COVID-19 patients. Mass spectrometry and ELISAs with recombinant proteins identified IgA auto-Abs that target human surfactant proteins B and C. In line with these findings, lungs of deceased COVID-19 patients showed reduced pulmonary surfactant. Our data suggest that IgA-driven autoimmunity against surfactant may result in disease progression of COVID-19.