Dr Balmaceda, a gastrointestinal medical oncologist at MD Anderson Cancer Center, opens with a patient who presented with abdominal pain, fatigue, and weight loss, and was found to have a pancreatic head mass with liver metastases and biopsy-confirmed pancreatic ductal adenocarcinoma. The patient responded to first-line combination chemotherapy before progressing, and comprehensive genomic profiling returned a KRAS mutation with a co-occurring TP53 alteration, microsatellite stable disease, and low tumor mutational burden. Dr Lee, a gastrointestinal medical oncologist at Stanford University, calls that a standard profile for the disease and notes that TP53 has no drug targeting it directly, while the microsatellite stable, low tumor mutational burden findings make immunotherapy unlikely to help. Dr Balmaceda then describes KRAS as an on and off switch that cycles between guanosine triphosphate and guanosine diphosphate bound states and stays locked on when mutated, and explains that molecular imaging revealed the pocket that finally made a long-standing undruggable target reachable.

Dr Lee, a gastrointestinal medical oncologist at Stanford University, gives a primer on reading KRAS results on a next-generation sequencing report, explaining that the letter, number, letter format identifies the codon and the amino acid change. Most pancreatic ductal adenocarcinoma mutations involve the same glycine residue, with G12D the most common, followed by G12V and G12R, while G12C, familiar from lung cancer, is uncommon here. He notes retrospective evidence that alleles differ prognostically, differing sensitivity to KRAS inhibitors, and active trial development around specific alleles. Dr Balmaceda, a gastrointestinal medical oncologist at MD Anderson Cancer Center, adds that co-mutations in TP53, CDKN2A, and SMAD4 affect genomic stability, cell cycle regulation, and the tumor microenvironment, but are not yet used to select standard therapy. Dr Lee closes by urging comprehensive sequencing at diagnosis, noting platinum sensitivity conferred by DNA repair gene mutations, and cautioning that a negative liquid biopsy cannot rule out mutations because pancreatic tumors shed little circulating tumor DNA.

KRAS Dr Balmaceda, a gastrointestinal medical oncologist at MD Anderson Cancer Center, frames the recent US Food and Drug Administration approval of daraxonrasib, a multi-selective inhibitor of the active form of RAS and the first pan-RAS targeted therapy cleared for metastatic pancreatic cancer, against the narrower allele-selective approach represented by sotorasib and adagrasib. Dr Lee, a gastrointestinal medical oncologist at Stanford University, says he cannot overstate the impact of the approval, calling it a paradigm shift that opens new treatment strategies and revives previously ineffective ones. He describes the registrational trial, which randomized patients with previously treated metastatic pancreatic cancer to daraxonrasib or investigator's choice chemotherapy and did not require a RAS mutation for entry, and reports that it met both its overall survival and progression-free survival endpoints while delivering more durable pain control and better quality of life. Dr Balmaceda previews first-line and adjuvant trials, KRAS vaccines, and known resistance mechanisms.