King, Gentry Teng

Background: Stromal hyaluronic acid (HA) poses a physical barrier and protects tumor cells from immune surveillance. Stroma targeting with pegylated human recombinant PH20 hyaluronidase (PEGPH20) demonstrated improved infiltration of cytotoxic T-lymphocytes and delivery of chemotherapy and PD1/PD-L1 antibodies in tumor models. This multicenter phase II study of PEGPH20 plus pembrolizumab evaluated the efficacy, safety and immune and stromal biomarkers in patients with HA-high refractory metastatic pancreatic ductal adenocarcinoma (mPDA). Patients and Methods: Patients were treated with PEGPH20 3 µg/kg IV weekly and pembrolizumab 200 mg IV in 3-week cycles. Tumor and blood samples were collected at baseline and on-study for biomarker analyses. Results: Between May and November 2019, 38 patients were screened and 8 treated, with median age 68 years (range 60–73) and median two (range 1–4) prior therapies. The study was closed to accrual early by pharmaceutical sponsor. Treatment was well tolerated, with expected grade 1/2 musculoskeletal toxicities. Best response was stable disease in 2 of 7 evaluable patients (29%). Median overall and progression-free survival were 7.2 months (95% CI 1.2–11.8) and 1.5 months (95% CI 0.9–4.4), respectively. Prolonged survival (range 10.2–27.6 months) occurred in patients treated with subsequent chemotherapy. Higher baseline tumor T cell receptor (TCR) clonality correlated with longer survival. Conclusions: Pembrolizumab with PEGPH20 was safe but did not have significant efficacy in refractory HA-high metastatic PDA.

567 Background: IDH2 mutation is rare (1%) in patients (pts) with cholangiocarcinoma and there are no data on prognosis in these pts and response to first line (1L) chemotherapy or off-label IDH2 inhibitor enasidenib. Methods: This IRB approved retrospective study included consecutive pts 18 years or older with IDH2 mutated biliary cancer identified between 2010-2024 at 4 large academic centers. Pt characteristics, systemic therapy(ies), next-generation sequencing (NGS) and survival data were obtained via review of electronic medical records. Survival probabilities were estimated using the product-limit method of Kaplan-Meier using SAS (v9.4, Cary, NC). Results: In 40 pts who met criteria, 9 (22.5%) underwent curative intent resection/ ablation, 34 (85%) had recurrent or de novo locally advanced or metastatic stage and of them 33 (82.5%) received any therapy for advanced cancer. Of these 33 pts, 25 (75.7%) were female, 29 (87.9%) non-Hispanic White and 32 (97%) had intrahepatic subtype with a median (range) age of 65 (28-82) years. NGS on tissue (51.5%), plasma (21.2%) or both tissue and plasma (27.3%) identified IDH2 R172* in 28 (84.8%), I98T in 1 (3%), F278fs in 1 (3%) pts and not reported/missing in 1 (3%) pt. Most common co-altered genes included TP53 (27.5%), ARID1A (17.5%), PBRM1 (12.5%), CDKN2A (10%), BAP1 (10%). FGFR2 fusion or N/KRAS mutation was present in 2 (5%) pts each. Of 33 pts with advanced stage, 1L therapy was gemcitabine/platinum +/- devimistat or durvalumab in 84.9%. Median (95% CI) progression-free survival (PFS) on 1L chemotherapy and overall survival were 6.6 (4.1-7.8) and 16.3 (12.1-28.9) months, respectively. Eight of 33 (24.2%) pts with advanced stage received off label enasidenib as Nth line therapy with median PFS (95% CI) 3.9 (1.1-5.1) months. Conclusions: Most pts with IDH2 mutation had advanced ds with median survival similar to those with IDH1 mutated advanced cholangiocarcinoma. Off label enasidenib had modest benefit in this rare subset of pts and should be investigated further.

PURPOSE SWOG S1815 was a randomized, open label phase III trial, evaluating gemcitabine, nab-paclitaxel, and cisplatin (GAP) versus gemcitabine and cisplatin (GC) in patients with newly diagnosed advanced biliary tract cancers (BTCs). METHODS Patients with newly diagnosed locally advanced unresectable or metastatic BTC, including intrahepatic cholangiocarcinoma (ICC) and extrahepatic cholangiocarcinoma (ECC) and gallbladder carcinoma (GBC), were randomly assigned 2:1 to either GAP (gemcitabine 800 mg/m 2 , cisplatin 25 mg/m 2 , and nab-paclitaxel 100 mg/m 2 intravenously once per day on days 1 and 8 of a 21-day cycle) or GC (gemcitabine 1,000 mg/m 2 and cisplatin 25 mg/m 2 intravenously once per day on days 1 and 8 of a 21-day cycle). RESULTS Among 452 randomly assigned participants, 441 were eligible and analyzable, 67% with ICC, 16% with GBC, and 17% with ECC. There was no significant difference in overall survival (OS) between GAP versus GC. Median OS with GAP was 14.0 months (95% CI, 12.4 to 16.1) and 13.6 months with GC (95% CI, 9.7 to 16.6); hazard ratio (HR), 0.91 (95% CI, 0.72 to 1.14); P = .41. Median progression-free survival (PFS) was similar between groups with median PFS for GAP being 7.5 months (95% CI, 6.4 to 8.5) versus 6.3 months for GC (95% CI, 4.4 to 8.2); HR, 0.89 (95% CI, 0.71 to 1.12); P = .32. In exploratory subset analyses, the OS and PFS benefits of GAP versus GC treatment were greater in locally advanced disease compared with metastatic disease, although not statistically significant (interaction P = .14 for OS and P = .17 for PFS). Moreover, GAP versus GC showed greater improvement in PFS among participants with GBC than those with ICC or ECC (interaction P = .01), but not OS (interaction P = .28). CONCLUSION The addition of a taxane in the GAP regimen to the standard gemcitabine-cisplatin regimen did not improve OS in newly diagnosed BTC. More toxicity was encountered with GAP versus GC.

Abstract Fibroblast growth factor receptors (FGFR) are emerging as an important therapeutic target for patients with advanced, refractory cancers. Most selective FGFR inhibitors under investigation show reversible binding, and their activity is limited by acquired drug resistance. This review summarizes the preclinical and clinical development of futibatinib, an irreversible FGFR1-4 inhibitor. Futibatinib stands out among FGFR inhibitors because of its covalent binding mechanism and low susceptibility to acquired resistance. Preclinical data indicated robust activity of futibatinib against acquired resistance mutations in the FGFR kinase domain. In early-phase studies, futibatinib showed activity in cholangiocarcinoma, and gastric, urothelial, breast, central nervous system, and head and neck cancers harboring various FGFR aberrations. Exploratory analyses indicated clinical benefit with futibatinib after prior FGFR inhibitor use. In a pivotal phase II trial, futibatinib demonstrated durable objective responses (42% objective response rate) and tolerability in previously treated patients with advanced intrahepatic cholangiocarcinoma harboring FGFR2 fusions or rearrangements. A manageable safety profile was observed across studies, and patient quality of life was maintained with futibatinib treatment in patients with cholangiocarcinoma. Hyperphosphatemia, the most common adverse event with futibatinib, was well managed and did not lead to treatment discontinuation. These data show clinically meaningful benefit with futibatinib in FGFR2-rearrangement-positive cholangiocarcinoma and provide support for further investigation of futibatinib across other indications. Future directions for this agent include elucidating mechanisms of resistance and exploration of combination therapy approaches.