Abstract 5183: Retrospective analysis of CCNG1 expression in tumors, a novel biomarker in development for partnering with DRG-101, a tumor targeted retrovector encoding a CCNG1 inhibitor gene
Authors: Omelchenko Nadezhda , Kumar Vaishali , Jeffrey Samantha , Haroun Grace , Brigham Don , Isacoff William H. , Chawla Sant 
Published: March 2024

Background: CCNG1, a non-canonical cyclin, is a novel biomarker in development for partnering with DRG-101 (DeltaRex-G), a tumor targeted retrovector encoding a CCNG1 inhibitor gene. Expanded access using DRG-101 is currently open for an intermediate-size population of advanced pancreatic cancer, sarcoma and carcinoma of breast (NCT04091295). Therefore, it is important to identify patients who might respond favorably to DRG-101 gene therapy. Previously, we reported that CCNG1 expression is enhanced in sarcoma tumors (Ann Oncol 34, 1980P, 2023). In this report, we have expanded the analysis to 137 patients with all cancer types and describe patients with known CCNG1 expression levels who have been treated with DRG-101.

Methods: Archived formalin-fixed paraffin-embedded (FFPE) tumor specimens (n=137) from patients who were followed at the Sarcoma Oncology Research Center were collected, processed, and subjected to RNA sequencing. Briefly, RNA-seq libraries were sequenced to generate 50 million reads, aligned using Kallisto v0.42.4 to GENCODE v23 transcripts with default parameters. Only protein-coding, IGH/K/L- and TCR-related transcripts were retained for downstream processing, resulting in 20,062 protein-coding genes. Gene expression levels in patients of the reference cohorts are categorized as low/medium/high, defined by Low = &lt; 17%; Medium-high = 50%-83%; Medium-low = 17%-49%; High = &gt;83%.

Results: Seventy women and sixty-seven men, ranging in age from 16 to 87 years, were studied. All tumors showed enhanced CCNG1 expression. Thirty (22%) tumors exhibited high CCNG1 expression, 53 (39%) showed medium-high CCNG1 expression, 48 (35%) displayed medium-low CCNG1 expression, and six (4%) had low CCNG1 expression. One hundred (73%) patients had metastatic disease, and 37 (27%) had localized disease. There was no correlation between CCNG1 expression and disease stage. As a result of these findings, the FDA-CBER authorized the use of DRG-101 in an Expanded Access program as platform therapy upon which one or more FDA approved cancer drugs/immunotherapies may be added. Historically, one patient with metastatic pancreatic cancer, one with early stage, HR+ HER2+ invasive breast cancer and one with early stage triple negative breast cancer are alive 15, 3 and 2.5 years in sustained remission with DRG-101 therapy, and had 24%, 23% and 74% CCNG1 tumor expression levels respectively. Five patients with advanced pancreatic cancer, sarcoma and breast cancer and known CCNG1 expression levels are currently being treated with DRG-101.

Conclusions:(1) 100% of tumors tested showed enhanced CCNG1 expression at varying levels, and (2) the use of DRG-101 in combination with FDA approved cancer drugs/immunotherapies is on-going for an intermediate size population of advanced pancreatic cancer, sarcoma and carcinoma of breast.

Citation Format: Nadezhda Omelchenko, Vaishali Kumar, Samantha Jeffrey, Grace Haroun, Don Brigham, William H. Isacoff, Sant Chawla. Retrospective analysis of CCNG1 expression in tumors, a novel biomarker in development for partnering with DRG-101, a tumor targeted retrovector encoding a CCNG1 inhibitor gene [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5183.