Knox, J J

PURPOSE EGFR alterations occur in a subset of biliary tract cancers (BTCs) and are often linked to disease progression and poor prognosis, yet targeted approaches remain underexplored. ERRFI1 , encoding the epidermal growth factor receptor (EGFR) inhibitor MIG6, is mutated in various cancers, including BTC, representing a potential predictive biomarker. We investigated whether loss of ERRFI1 function may enhance sensitivity to EGFR-targeted tyrosine kinase inhibitors (TKIs), presenting a potential therapeutic opportunity. METHODS This is a retrospective multicenter study of patients with BTC harboring ERRFI1 alterations. Data were extracted from electronic health records following institutional approval. ERRFI1 alterations were classified based on the alteration type, variant allele frequencies were documented, and coalterations were analyzed. Treatment outcomes including response, time to progression (TTP), overall survival (OS), safety profiles, and tumor marker kinetics were noted. RESULTS Fourteen BTC patients with ERRFI1 mutations were identified in our database; the median age was 50 years, 64% were males; all cases were intrahepatic cholangiocarcinomas. Common coalterations included IDH1 (36%), TP53 (29%), and ARID1A (29%). All patients received gemcitabine-cisplatin as first-line treatment, and 79% received immune checkpoint inhibitors. Eight patients (57%) received EGFR TKIs. Best responses to EGFR therapy included three partial responses (2 responses lasting >20 months), four stable diseases, and one progressive disease. The median TTP was 7 months (95% CI, 6 to 21 months). Treatment was well-tolerated: toxicities included rash (n = 2), transaminitis (n = 1), and diarrhea (n = 1). The median OS was 20 months (95% CI: 8-36 months); 50% remained alive at last follow-up. CONCLUSION ERRFI1 mutations represent actionable biomarkers in BTC, with EGFR-targeted therapy demonstrating meaningful clinical benefit in this heavily pretreated population. These findings support integration of ERRFI1 testing into routine molecular profiling of BTC and other EGFR-driven malignancies.

PURPOSE Cholangiocarcinoma is a rare cancer associated with poor prognosis. Pemigatinib was the first FGFR1-3 inhibitor approved for second-line therapy and beyond, on the basis of the phase II FIGHT-202 trial. Here, we assess efficacy and safety of first-line pemigatinib. METHODS FIGHT-302 is a phase III, randomized, global trial evaluating pemigatinib as first-line therapy (ClinicalTrials.gov identifier: NCT03656536 ). Adults with advanced cholangiocarcinoma with FGFR2 rearrangement were randomized 1:1 to receive pemigatinib (13.5 mg once daily) or chemotherapy (1,000 mg/m 2 gemcitabine plus 25 mg/m 2 cisplatin once per day on days 1 and 8 of every 3-week cycle for ≤8 cycles) and were stratified by prior receipt of chemotherapy, geographic region, and tumor burden. Pemigatinib crossover was allowed for patients progressing on chemotherapy. The primary end point was progression-free survival (PFS). Secondary efficacy, safety, and exploratory end points were also analyzed. RESULTS Overall, 4,563 patients were prescreened, 196 were screened, and 167 randomly assigned to receive pemigatinib (n = 83) or chemotherapy (n = 84) before early closure of the study because of a change in standard of care. The median PFS was 8.3 months in the pemigatinib group versus 6.8 months in the chemotherapy group (hazard ratio, 0.58 [95% CI, 0.39 to 0.87]; nominal P = .0078); objective response rate was 47% versus 15%, and the median duration of response was 14.2 versus 6.3 months. Median overall survival was similar (24.4 v 25.0 months, respectively). In the crossover group (n = 42, second-line pemigatinib), the median PFS was 8.1 months. Safety was consistent with the known profile of pemigatinib. CONCLUSION To our knowledge, this was the largest, first-line, randomized, phase III trial of a targeted therapy for advanced FGFR2- rearranged cholangiocarcinoma. Pemigatinib demonstrated prolonged median PFS compared with chemotherapy, with no new safety findings.