Borad, Mitesh J.

463 Background: Molecularly targeted therapy is gaining traction in cholangiocarcinoma with the first FDA approval of a targeted agent in 2020, the FGFR inhibitor pemigatinib. Yet response rates and efficacy are modest, and most cholangiocarcinoma patients still lack targeted therapy options. The hippo pathway effector, YAP, is an oncogene that is activated in the majority of cholangiocarcinoma, yet attempts to develop YAP inhibitors have not yet been clinically successful. Recently, we described a novel mechanism of YAP regulation, via tyrosine phosphorylation by the Src-family kinase LCK. Therefore we hypothesized that LCK inhibition by may be therapeutic in cholangiocarcinoma through suppression of YAP activity. Methods: NTRC 0652-0 is a novel tyrosine kinase inhibitor with specificity for LCK. In vitro pharmacodynamics were defined. In cholangiocarcinoma cells, specificity for LCK inhibition was determined by mass spectrometry-based unbiased analysis of the tyrosine phosphoproteome following treatment with NTRC 0652-0 or genetic deletion of LCK. YAP phosphorylation and cotranscriptional activity, cell viability, and apoptosis were assessed. A panel of eight cholangiocarcinoma patient derived organoids (PDO) were characterized and tested for sensitivity to NTRC 0652-0. Two patient-derived xenograft (PDX) models bearing FGFR2-rearrangements were utilized for in vivo assessment of pharmacokinetics, toxicity, and efficacy. Results: NTRC 0652-0 demonstrated selectivity for LCK inhibition in vitro and in cholangiocarcinoma cells. NTRC 0652-0 treatment led to YAP inhibition and apoptotic cell death in cholangiocarcinoma cell lines, associated with inhibition of MCL1 expression. PDOs demonstrated variable sensitivity to NTRC 0652-0, correlated with basal YAP tyrosine phosphorylation and drug-induced suppression of YAP co-transcriptional activity. FGFR2-altered cholangiocarcinoma was also identified as a subset with enrichment of YAP target genes. Cells from an FGFR2-altered PDX were sensitive to NTRC 0652-0 despite being primarily resistant to pemigatinib. In two PDX models of FGFR2-altered cholangiocarcinoma, daily oral treatment with NTRC 0652-0 inhibited YAP tyrosine phosphorylation, and resulted in stable plasma and tumor drug levels, acceptable toxicity, and significantly decreased tumor growth. Conclusions: A novel LCK inhibitor, NTRC 0652-0, reduced YAP signaling and demonstrated preclinical efficacy in multiple patient-derived models of cholangiocarcinoma. LCK is a novel therapeutic target in cholangiocarcinoma, and YAP activation or FGFR2-alteration are potential biomarkers for response.

440 Background: Futibatinib, an irreversible FGFR1–4 inhibitor, is being investigated for the treatment of advanced intrahepatic cholangiocarcinoma (iCC) with FGFR2 fusions/rearrangements. We conducted an indirect treatment comparison to evaluate efficacy outcomes with futibatinib for advanced iCC patients from the FOENIX-CCA2 trial (NCT02052778) relative to published data for chemotherapy and FGFR inhibitors. Methods: A systematic literature review was conducted to identify clinical trials for FGFR inhibitors published 01/2015-02/2021, with additional targeted searches for chemotherapy data. A simulated treatment comparison was conducted using individual-level patient data from FOENIX-CCA2 and published aggregate data from comparator trials, applying regression models to adjust for between-trial differences in baseline characteristics. Population-adjusted Cox regression models were used for base case time-to-event outcomes (progression-free survival [PFS], overall survival [OS], duration of response [DOR]) and binomial-logistic regressions for binary outcomes (objective response rate [ORR]). Results: Two studies of FGFR inhibitors among previously treated patients with FGFR2 fusions/rearrangements were identified with sufficient data for analysis: FOENIX-CCA2 (n=103) and FIGHT-202 (n=107, pemigatinib). Two studies were identified for chemotherapy in this setting (an analysis of prior systemic therapy in the FIGHT-202 cohort [n=53] and a natural history study using a clinicogenomic database [n=71]). Comparisons of futibatinib with chemotherapy showed significantly lower risk of progression or death with futibatinib (table). Comparisons of futibatinib with pemigatinib showed similar outcomes between treatments (table), however, there was a numerical advantage for futibatinib in all efficacy parameters. Conclusions: Data suggest that futibatinib provides longer survival vs chemotherapy among previously treated advanced iCC patients with FGFR2 fusions/rearrangements. No statistically significant differences were observed in efficacy outcomes between futibatinib and pemigatinib, although numerical trends favored futibatinib. Molecular detail such as improved activity against co-mutated tumours and resistance mutations may explain such trends. [Table: see text]

427 Background: Derazantinib, a potent anti- FGFR1-3 oral kinase inhibitor, has shown clinically meaningful anti-tumor activity (21%), durable responses (median, 6.4 months), and progression-free survival (median, 8.0 months) in patients (pts) with FGFR2 fusion (FGFR2F)-positive intrahepatic cholangiocarcinoma (iCCA), and with a manageable toxicity profile. Herein, we report an interim analysis of the clinical efficacy data of derazantinib for pts with iCCA harboring FGFR2 mutations or amplifications (FGFR2M/A), a potential therapeutic option currently not addressed by FGFR inhibitors. Methods: Study FIDES-01 enrolls in a dedicated cohort pts with FGFR2M/A+ advanced iCCA who received previous chemotherapy. Pts receive 300 mg derazantinib daily until disease progression, death or intolerance. The primary endpoint is the proportion of pts alive and free of disease progression at 3 months (PFS3; RECIST 1.1, central imaging review) using a Simon’s two-stage sample-size minimizing statistical design. The interim analysis population comprises 23 pts dosed (intention to treat) who had at least one post-baseline tumor assessment (or clinical progression, or died) by June 3, 2021, using investigator assessments based on RECIST 1.1. Results: To date, 28 pts have been enrolled and dosed. FGFR2M/A observed in these pts included missense point mutations (78%), other short variants (11%) and amplifications (11%). Transition from stage 1 to stage 2 of the study was achieved earlier than planned after 8 (67%) of 12 pts were assessed as PFS3 based on central imaging review. In 23 pts included in this interim analysis for efficacy, the best overall response (investigator assessment) was confirmed partial response in two (8.7%) and stable disease in additional 15 pts (65.2%), resulting in a disease control rate of 73.9% (95% CI, 51.6–89.8). Using Kaplan-Meier analyses, the median PFS was 7.3 months (95%CI, 3.5–16.7) and the probability of being progression-free at 3 months and at 6 months were 76.3% (95%CI, 51.9–89.4) and 50.3% (95%CI, 21.7–73.4), respectively. Clinically meaningful anti-tumor efficacy was observed across all types of genetic aberrations. The safety profile of derazantinib in FGFR2M/A+ iCCA pts was consistent with that previously reported for FGFR2F+ iCCA pts. Conclusions: This interim data in study FIDES-01 suggest that derazantinib treatment provides clinical benefit to pts with advanced iCCA harboring FGFR2M/A who progressed after at least one line of standard chemotherapy. To our knowledge, this is the first report of clinically meaningful anti-tumor efficacy in a prospectively planned cohort of iCCA pts harboring FGFR2M/A. The study is ongoing to accrue 43 patients, assessing derazantinib as a therapeutic option for FGFR2M/A+ iCCA pts after disease progression on first-line treatment. Clinical trial information: NCT03230318.

190 Background: Metastatic colorectal (CRC), pancreatic (PANC), and gastroesophageal (GE) cancers are the leading causes of GI cancer–related mortality (5-yr survival rate, 14%, 3% and ̃5-6%, respectively). T-cell immunotherapy targeting GI-associated tumor antigens has been attempted, but efficacy has been constrained by on-target off-tumor toxicity, limiting the therapeutic window. The Tmod (TM) platform is an AND-NOT logic-gated CAR T modular system, versions of which have a CEA- or MSLN-targeting CAR activator and a separate HLA-A*02-targeting blocker receptor to protect normal cells. Tmod CAR T exploits HLA LOH, common in GI malignancies (10-33% in primary solid tumors [TCGA]) and can kill tumor cells without harming healthy cells in vitro and in vivo. However, the prevalence of HLA LOH across GI tumors is unknown in the real-world setting. We utilized the Tempus xT oncology NGS database of patients with multiple GI tumors. From a standard-of-care NGS assay, GI cancer patients can be readily identified for HLA LOH and future treatment with Tmod CAR T therapy. Methods: The occurrence of HLA LOH in GI tumors of 1439 patients was assessed using paired germline and somatic DNA sequencing using a research assay [6]. CRC, PANC and GE patients with ≥ stage 3 were then extracted, and rates of HLA LOH were identified (ie, whether loss occurred across high-frequency HLA-A alleles). In addition, mutations in KRAS and BRAF, as well as MSI status were stratified to determine any association with HLA-A LOH. Results: HLA-A LOH was detected in 830 (17.3%) of all solid tumor records, and a similar proportion when all GI cancer records were analyzed (17.0%). For GI subtypes, these values ranged from 13.5% to 23.1% (Table). No high-frequency HLA-A allele (A*01, A*02, A*03, A*11) was more likely to be lost. Clinical biomarkers ( KRAS, BRAF and MSI status) were not associated with HLA-LOH. Conclusions: The frequency of HLA LOH among advanced solid tumor cancers in this dataset is 17.3%, with a range of 13.5-23% between CRC, PANC and GE. The HLA LOH frequency observed in these GI tumors is consistent with that in primary tumors from TCGA, which also used germline-matched and tumor samples. Clinical biomarkers were not associated with HLA LOH. Tempus NGS was able to identify HLA LOH, which can be used for Tmod CAR T therapy to an enhanced therapeutic window. Identification of these patients in BASECAMP-1 (NCT04981119) will enable novel Tmod CAR T therapy. [Table: see text]

Purpose Clinical-pathologic features and natural history of patients with isocitrate dehydrogenase ( IDH)-mutant intrahepatic cholangiocarcinoma (CCA) are not well characterized. Here, we sought to describe the natural history, clinical phenotype, and prognostic impact of advanced, IDH-mutated CCA. METHODS We conducted a multicentric, retrospective analysis of patients with IDH-mutated (IDH1 or IDH2) CCA between 2010 and 2020. Median overall survival (OS) and progression-free survival (PFS) analyses were performed using the Kaplan-Meier method. Chi-square test was used to analyze disease control rate (DCR) and overall response rate (ORR). Matched controls were used for comparing survival between patients with and without IDH mutations (mIDH). RESULTS Sixty-five patients with IDH-mutated CCA were included. All patients had intrahepatic CCA. On first-line chemotherapy, median OS and median PFS were 21.2 months and 8.3 months, respectively. Notably, median OS (32.4 v 19.5 months, P = .12) and PFS (18.0 v 8.0 months, P = .12) were not significantly affected by disease status at presentation (locally advanced v metastatic, respectively). Median OS was significantly longer in patients with mIDH (21.2 v 10.5 months; P < .01). First-line gemcitabine-containing regimens had a significantly higher DCR and ORR than non–gemcitabine-containing regimens (DCR: 75% v 33%, P = .01; ORR: 39% v 0%, P = .02). In patients receiving IDH inhibitor therapy, median PFS was 4.6 months with a DCR of 29%. CONCLUSION CCA with m IDH confers a unique subtype resulting in a better survival compared with that of counterparts. IDH inhibitors represent a promising therapeutic option in later lines of therapy in this subgroup.