Abstract 5387: Discovery of plasma protein biomarkers associated with overall survival in R/R DLBCL patients treated with loncastuximab tesirine
Authors: Vallania Francesco , Cheung Victoria , Tripathi Anupriya , Louie Maggie , Snyder Thomas , Lin Jimmy , Havenith Karin , Qin Yajuan , Pantano Serafino , Wuerthner Jens , van Berkel Patrick H. 
Published: June 2023

Abstract
Plasma proteomics is a non-invasive source of potential biomarkers associated with cancer treatment outcomes, including disease progression and overall survival (OS). Loncastuximab tesirine (lonca) is an antibody-drug conjugate, composed of a humanized anti-CD19 antibody conjugated to a pyrrolobenzodiazepine dimer cytotoxin, for the treatment of relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL). Here, we investigated the association of plasma protein biomarkers with OS of R/R DLBCL patients prior to treatment with lonca (phase 2 trial, NCT3589469, LOTIS-2). Abundances of 888 plasma proteins, including inflammation, cancer and DNA repair associated markers, were measured for 69 patients with R/R DLBCL from plasma samples collected at baseline. Protein markers predictive of OS were selected using a L1 regularized Cox proportional hazards model (CoxPH) incorporating survival time and censoring status. Protein modules associated with OS were discovered by performing principal component analysis (PCA) on scaled protein abundances. Gene Set Enrichment Analysis (GSEA) was performed using Molecular Signatures Database (MSigDB) sets. We initially applied a regularized COX proportional hazards model to our proteomics dataset to identify proteins associated with OS, which revealed 5 protein markers (associated with decreased survival = REG3A, LAP3; associated with increased survival = NPTXR, C1QTNF1, FLT3) which stratified patients into distinct survival groups (p = 2.3e-4). As a complement to this approach and to extend our biological understanding of this cohort, we then applied PCA to the proteomics data to reveal underlying protein modules associated with survival. Our analysis identified principal component 3 (PC3) to have the strongest association to OS (rho= -0.63, FDR = 8.7e-07); with its top loadings consisting of known markers of cancer progression (top 3 proteins: SIGLEC10, IL6, TNFRSF6B). GSEA on PC3 loadings identified 68 significantly enriched gene sets (FDR &lt; 5%). Gene sets reflective of changes in immune activation, increased cytokine activity and interleukin mediated activation (IL6, IL10) were negatively associated with OS, including activation of the following Hallmark pathways: IL6/JAK/STAT3 signaling and inflammatory response pathways.Overall, our results identify proteomics markers associated with DLBCL survival upon treatment with lonca, highlighting the potential of plasma proteins as a source of relevant biomarkers pending additional validation.
[FV and VC contributed equally to this work]
Citation Format: Francesco Vallania, Victoria Cheung, Anupriya Tripathi, Maggie Louie, Thomas Snyder, Jimmy Lin, Karin Havenith, Yajuan Qin, Serafino Pantano, Jens Wuerthner, Patrick H. van Berkel. Discovery of plasma protein biomarkers associated with overall survival in R/R DLBCL patients treated with loncastuximab tesirine. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5387.