Landscape of metastatic colorectal cancer (CRC) using comprehensive circulating tumor DNA (ctDNA) next-generation sequencing (NGS) in India: Expanding beyond RAS and RAF.

49 Background: Traditional testing in mCRC primarily focuses on RAS and RAF mutations. However, a broader range of emerging biomarkers, collectively termed the "Pressing panel" (PP), identifies patients with RAS/RAF wild-type (wt) tumors who may particularly benefit from anti-EGFR therapy. Comprehensive liquid biopsies provide a non-invasive method for identifying traditional and emerging biomarkers. Limited genomic data, including the prevalence of PP alterations (alts), is available for mCRC patients in India tested by ctDNA NGS. Methods: We reviewed the results of Guardant360 (Guardant Health, Inc.) ordered for patients with mCRC as part of routine clinical practice in India through July 2024. NGS analyzed plasma samples at a CLIA-certified, CAP-accredited central laboratory. Guardant360 analyzes ctDNA for mutations (mts), insertions and deletions, amplifications (amps), and fusions in up to 83 genes, including PP genes, i.e., KRAS, NRAS, BRAF, ERBB2, PIK3CA, PTEN, AKT1, ALK, ROS1, NTRK, RET, and MSI status. The Indian cohort's prevalence of PP mts was compared to that from other countries in Asia and Middle East (AME). Timing of testing relative to line of therapy was unknown. Results: Among 145 samples from India, ctDNA was detected in 92% (n=134). Median age was 59 years, with women comprising 40%. The median turnaround time from blood collection to result was 7 days. The mean mts count per sample was 5, and the median variant allele frequency was 1.5%. Frequent mts were in APC (53%), KRAS (56%), and SMAD4 (13%), while amps of EGFR (16%) and FGFR1 (9%) were common. Clinically relevant fusions were observed in 3% of patients. KRAS, NRAS, and/or BRAF V600E alterations were found in 63% of both India and AME samples. PP alts were identified in 24% and 27% of Indian and AME patients, respectively. Most frequent PP alts included PIK3CA (15%), PTEN (3%), and MET amp (2%). The prevalence of most of the PP alts was similar between the Indian and AME cohorts (Table), with minor differences observed in PIK3CA (15% vs 18%) and MSI-High (3% vs 1%). In patients with RAS/RAF wild-type lacking EGFR-amp, 9.5% (India) and 18% (AME) harbored at least one PP alt. Conclusions: This study highlights the role of liquid CGP for characterizing the mutational landscape and identifying PP mts for patients from India with advanced CRC. Pressing panel alterations. PP Alteration INDIA % (n=134) AME % (n=720) ERBB2 Amp 1% 2% MET Amp 2% 3% ALK Fusion 0% 0% ROS1 Fusion 0% 0% NTRK1 Fusion 1% 0% RET Fusion 0% 1% ERBB2 Mut 1% 2% PIK3CA Mut 15% 18% PTEN Mut 3% 3% AKT1 Mut 0% 1% MSI-High 3% 1%