Abstract 3379: Comprehensive circulating tumor DNA and CTC profiling of treatment naïve early-stage head and neck cancer patients reveals early signature of disease progression

Comprehensive CtDNA and CTC profiling of treatment naïve early-stage head and neck cancer patients reveals early signatures of disease progressionBackground: We performed comprehensive ctDNA analysis on early-stage HNC patients in a pilot study to determine the mutational landscape in HNC patients with a known tobacco history. Methods: We analysed ctDNA of 18 early-stage HNC patients for genomic landscapes using the illumina NextSeq 2000 NGS. A custom-designed OncoIndex gene panel was used for the hybrid capture target-enrichment of critical cancer genes. Panel was designed to detect cancer targeting exonic sequence of 600 genes reporting SNVs and indels along fusions and copy number amplification. The gene panel detected genome-wide signatures including bTMB, MSI (microsatellite instability), HRD (homologous recombination deficiency) prediction and calculate cfDNA tumor fraction. Results: 80 % patients showed presence of at least one CTC in peripheral blood, possibly indicating the progressive disease at the time of presentation. Comprehensive genomic profile obtained from plasma cfDNA of early-stage HNC cancer patients predominantly had low bTMB and MSI Scores (99 % patients). However, HRD and LOH matrix was high for 60 % patients indicating highly dysregulated DNA repair activities. Concurring to these observations, 98 % patients had mutations in key tumor suppressor and DNA damage response (DDR) genes possibly resulting in their loss of function. Besides DNA damage pathway, 60% patients harboured alterations in RTK genes including FGFR, EGFR and PDEGFR family and 32% patients showed activating mutations in Erk1 and its upstream regulators. MSH2 was the most prominently mutated gene (37%) followed by FGFR (32%). Surprisingly, unlike HPV positive advanced HNC cases, TP53 mutations were not detected in any patient, though alterations in TS genes were most prevalent in the study population. 51% alterations resulted into truncated proteins possibly impairing their functions, while 42% alterations were point mutations, 6 % were frameshift and 1 % indels. Presence of mutations in BRAF, PDGFR, FGFR and KIT genes suggested for the potential therapy resistance. Tumor fraction representing ctDNA showed elevated range from 20 % to 45 % with a corresponding ploidy between 2 to 4. Conclusions: Comprehensive ctDNA profile showed major gene alterations in TS and DDR response pathway genes besides mutations in proliferative signaling members. TP53 mutation was not detected, although critical tumor suppressor and DDR genes were predominantly mutated, suggesting for a unique mutation pattern associated with early-stage HNC due to tobacco etiology. Our results suggest that comprehensive ctDNA analysis along CTC profiling can predict the disease progression beforehand and may offer new treatment options to early-stage HNC patients.

Citation Format: Gowhar Shafi, Atul Bharde, Fauzul Moubeen, Kanchan Hariramani, Alain D’Souza, Trupti Kad, Bhagwat Jadhav, Sangita Prajapati, Aditi Rani, Madhura Basavalingegowda, Mohan Uttarwar, Gourishankar Aland, Sreeja Jayant, Aravindan Vasudevan, Pankaj Chaturvedi, Jayant Khandare. Comprehensive circulating tumor DNA and CTC profiling of treatment naïve early-stage head and neck cancer patients reveals early signature of disease progression [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 3379.

Abstract PR007: Comprehensive ctDNA profiling reveals potential metastatic genomic signatures in treatment-naive early-stage breast cancer patients

Background: Genomic profiling has revolutionized precision oncology impacting the diagnosis, prognosis, and therapy decisions. Considering high spatiotemporal diversity and heterogenicity of breast tumor-cell genomes, small-gene panels often fail to capture rare but important genomic alterations. Conversely, comprehensive ctDNA sequencing approaches enable the identification of under characterized ‘long tailed driver’ genomic alterations and capture Intra and inter metastatic heterogeneity. Here, we demonstrate the clinical utility of comprehensive genome profiling with higher sensitivity to predict the possibility of metastasis in early-stage breast cancer patients. Methods: We retrospectively analyzed ctDNA and genomic DNA (gDNA) from FFPE samples as well as circulating tumor cells (CTC) in 10 treatment-naive hormone positive and HER2 negative, primary-stage breast cancer patients [GS1] using the OncoIndx comprehensive 600 gene panel. The panel captures all important cancer-relevant genomic alterations including Tumor Mutation Burden (TMB), Micro Satellite Instability (MSI), homologous recombination deficiency (HRD) prediction, and cfDNA tumor fraction (TF). CTCs were enumerated from 1.5 ml of blood using the OncoDiscover platform approved by the Drug Controller General of India having anti-EpCAM antibody-mediated immunomagnetic nanoparticles. CTCs were confirmed for cytokeratin 18+ and DAPI + markers and the absence of CD45. Results: Comprehensive genomic profile obtained from ctDNA and gDNA from FFPE of early-stage breast cancer patients predominantly exhibited the presence of alterations in PIK3CA and ESR1 signaling pathways. PIK3CA mutations were present in 77% and 44% of baseline ctDNA and gDNA samples, while ESR1 mutations were present in 44% and 22% of baseline ctDNA and gDNA, respectively. In addition, we observed about 70% additional driver mutations in ctDNA samples suggesting shedding of ctDNA together with CTC (80% positive), a likely positive biomarker of metastasis. About 50% of the patients showed higher TMB and HRD. Notably, TF representing ctDNA varied between 13% to 27% in blood samples with a corresponding ploidy range of 2.9 to 4.7. Surprisingly, ~50% of the patient population matched the mutation profile of clinically confirmed metastatic patients. All the patients harboring potential metastatic driver alterations showed the presence of CTCs in peripheral blood. Conclusions: Comprehensive ctDNA genomic profiling showed potential metastasis driving alterations suggesting the role of ctDNA-based liquid biopsy to predict metastasis in early breast cancer patients. We observed enhanced TF at the time of diagnosis, possibly due to the presence of distant metastasis, high disease burden, and aggressive tumor biology. Our results suggest that ctDNA dynamics at the time of disease presentation can predict early metastasis, and may demonstrate the divergent response of tumor heterogeneity to treatment in early-stage breast cancer.

Citation Format: Gowhar Shafi, Manoj Dongare, Atul Bharde, Moubeen Fauzul, Kanchan Hariramani, Alain D’Souza, Bhagwat Jadhav, Trupti Kad, Sangeeta Prajapati, Vikas Jadhav, ManojKumar Kumaran, Sumit Haldar, Vatsal Mehra, Sujit Joshi, Gourishankar Aland, Richa Dave, Sreeja Jayant, Aravindan Vasudevan, Mohan Uttarwar, Jayant Khandare. Comprehensive ctDNA profiling reveals potential metastatic genomic signatures in treatment-naive early-stage breast cancer patients [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR007.