EGFR Inhibition Potentiates FGFR Inhibitor Therapy and Overcomes Resistance in FGFR2 Fusion-Positive Cholangiocarcinoma.

FGFR inhibitors are approved for the treatment of advanced cholangiocarcinoma harboring FGFR2 fusions. However, the response rate is moderate, and resistance emerges rapidly due to acquired secondary FGFR2 mutations or due to other less-defined mechanisms. Here, we conducted high-throughput combination drug screens, biochemical analysis, and therapeutic studies using patient-derived models of FGFR2 fusion-positive cholangiocarcinoma to gain insight into these clinical profiles and uncover improved treatment strategies. We found that feedback activation of EGFR signaling limits FGFR inhibitor efficacy, restricting cell death induction in sensitive models and causing resistance in insensitive models lacking secondary FGFR2 mutations. Inhibition of wild-type EGFR potentiated responses to FGFR inhibitors in both contexts, durably suppressing MEK/ERK and mTOR signaling, increasing apoptosis, and causing marked tumor regressions in vivo. Our findings reveal EGFR-dependent adaptive signaling as an important mechanism limiting FGFR inhibitor efficacy and driving resistance and support clinical testing of FGFR/EGFR inhibitor therapy for FGFR2 fusion-positive cholangiocarcinoma. We demonstrate that feedback activation of EGFR signaling limits the effectiveness of FGFR inhibitor therapy and drives adaptive resistance in patient-derived models of FGFR2 fusion-positive cholangiocarcinoma. These studies support the potential of combination treatment with FGFR and EGFR inhibitors as an improved treatment for patients with FGFR2-driven cholangiocarcinoma. This article is highlighted in the In This Issue feature, p. 1171.

Wu Q ，Zhen Y ，Shi L ，Vu P ，Greninger P ，Adil R ，Merritt J ，Egan R ，Wu MJ ，Yin X ，Ferrone CR ，Deshpande V ，Baiev I ，Pinto CJ ，McLoughlin DE ，Walmsley CS ，Stone JR ，Gordan JD ，Zhu AX ，Juric D ，Goyal L ，Benes CH ，Bardeesy N ... -  《-》

Convergent MAPK pathway alterations mediate acquired resistance to FGFR inhibitors in FGFR2 fusion-positive cholangiocarcinoma.

There is a knowledge gap in understanding mechanisms of resistance to fibroblast growth factor receptor (FGFR) inhibitors (FGFRi) and a need for novel therapeutic strategies to overcome it. We investigated mechanisms of acquired resistance to FGFRi in patients with FGFR2-fusion-positive cholangiocarcinoma (CCA). A retrospective analysis of patients who received FGFRi therapy and underwent tumor and/or cell-free DNA analysis, before and after treatment, was performed. Longitudinal circulating tumor DNA samples from a cohort of patients in the phase I trial of futibatinib (NCT02052778) were assessed. FGFR2-BICC1 fusion cell lines were developed and secondary acquired resistance mutations in the mitogen-activated protein kinase (MAPK) pathway were introduced to assess their effect on sensitivity to FGFRi in vitro. On retrospective analysis of 17 patients with repeat sequencing following FGFRi treatment, new FGFR2 mutations were detected in 11 (64.7%) and new alterations in MAPK pathway genes in nine (52.9%) patients, with seven (41.2%) patients developing new alterations in both the FGFR2 and MAPK pathways. In serially collected plasma samples, a patient treated with an irreversible FGFRi tested positive for previously undetected BRAF V600E, NRAS Q61K, NRAS G12C, NRAS G13D and KRAS G12K mutations upon progression. Introduction of a FGFR2-BICC1 fusion into biliary tract cells in vitro sensitized the cells to FGFRi, while concomitant KRAS G12D or BRAF V600E conferred resistance. MEK inhibition was synergistic with FGFRi in vitro. In an in vivo animal model, the combination had antitumor activity in FGFR2 fusions but was not able to overcome KRAS-mediated FGFRi resistance. These findings suggest convergent genomic evolution in the MAPK pathway may be a potential mechanism of acquired resistance to FGFRi. NCT02052778. We evaluated tumors and plasma from patients who previously received inhibitors of fibroblast growth factor receptor (FGFR), an important receptor that plays a role in cancer cell growth, especially in tumors with abnormalities in this gene, such as FGFR fusions, where the FGFR gene is fused to another gene, leading to activation of cancer cell growth. We found that patients treated with FGFR inhibitors may develop mutations in other genes such as KRAS, and this can confer resistance to FGFR inhibitors. These findings have several implications for patients with FGFR2 fusion-positive tumors and provide mechanistic insight into emerging MAPK pathway alterations which may serve as a therapeutic vulnerability in the setting of acquired resistance to FGFRi.

DiPeri TP ，Zhao M ，Evans KW ，Varadarajan K ，Moss T ，Scott S ，Kahle MP ，Byrnes CC ，Chen H ，Lee SS ，Halim AB ，Hirai H ，Wacheck V ，Kwong LN ，Rodon J ，Javle M ，Meric-Bernstam F ... -  《-》

Efficacy of FGFR Inhibitors and Combination Therapies for Acquired Resistance in FGFR2-Fusion Cholangiocarcinoma.

The fibroblast growth factor receptor (FGFR) signaling pathway is aberrantly activated in approximately 15% to 20% of patients with intrahepatic cholangiocarcinoma. Currently, several FGFR kinase inhibitors are being assessed in clinical trials for patients with FGFR-altered cholangiocarcinoma. Despite evidence of initial responses and disease control, virtually all patients eventually develop acquired resistance. Thus, there is a critical need for the development of innovative therapeutic strategies to overcome acquired drug resistance. Here, we present findings from a patient with FGFR2-altered metastatic cholangiocarcinoma who enrolled in a phase II clinical trial of the FGFR inhibitor, infigratinib (BGJ398). Treatment was initially effective as demonstrated by imaging and tumor marker response; however, after 8 months on trial, the patient exhibited tumor regrowth and disease progression. Targeted sequencing of tumor DNA after disease progression revealed the FGFR2 kinase domain p.E565A and p.L617M single-nucleotide variants (SNV) hypothesized to drive acquired resistance to infigratinib. The sensitivities of these FGFR2 SNVs, which were detected post-infigratinib therapy, were extended to include clinically relevant FGFR inhibitors, including AZD4547, erdafitinib (JNJ-42756493), dovitinib, ponatinib, and TAS120, and were evaluated in vitro Through a proteomics approach, we identified upregulation of the PI3K/AKT/mTOR signaling pathway in cells harboring the FGFR2 p.E565A mutation and demonstrated that combination therapy strategies with FGFR and mTOR inhibitors may be used to overcome resistance to FGFR inhibition, specific to infigratinib. Collectively, these studies support the development of novel combination therapeutic strategies in addition to the next generation of FGFR inhibitors to overcome acquired resistance in patients.

Krook MA ，Lenyo A ，Wilberding M ，Barker H ，Dantuono M ，Bailey KM ，Chen HZ ，Reeser JW ，Wing MR ，Miya J ，Samorodnitsky E ，Smith AM ，Dao T ，Martin DM ，Ciombor KK ，Hays J ，Freud AG ，Roychowdhury S ... -  《-》

TAS-120 Overcomes Resistance to ATP-Competitive FGFR Inhibitors in Patients with FGFR2 Fusion-Positive Intrahepatic Cholangiocarcinoma.

ATP-competitive fibroblast growth factor receptor (FGFR) kinase inhibitors, including BGJ398 and Debio 1347, show antitumor activity in patients with intrahepatic cholangiocarcinoma (ICC) harboring activating FGFR2 gene fusions. Unfortunately, acquired resistance develops and is often associated with the emergence of secondary FGFR2 kinase domain mutations. Here, we report that the irreversible pan-FGFR inhibitor TAS-120 demonstrated efficacy in 4 patients with FGFR2 fusion-positive ICC who developed resistance to BGJ398 or Debio 1347. Examination of serial biopsies, circulating tumor DNA (ctDNA), and patient-derived ICC cells revealed that TAS-120 was active against multiple FGFR2 mutations conferring resistance to BGJ398 or Debio 1347. Functional assessment and modeling the clonal outgrowth of individual resistance mutations from polyclonal cell pools mirrored the resistance profiles observed clinically for each inhibitor. Our findings suggest that strategic sequencing of FGFR inhibitors, guided by serial biopsy and ctDNA analysis, may prolong the duration of benefit from FGFR inhibition in patients with FGFR2 fusion-positive ICC. SIGNIFICANCE: ATP-competitive FGFR inhibitors (BGJ398, Debio 1347) show efficacy in FGFR2-altered ICC; however, acquired FGFR2 kinase domain mutations cause drug resistance and tumor progression. We demonstrate that the irreversible FGFR inhibitor TAS-120 provides clinical benefit in patients with resistance to BGJ398 or Debio 1347 and overcomes several FGFR2 mutations in ICC models.This article is highlighted in the In This Issue feature, p. 983.

Goyal L ，Shi L ，Liu LY ，Fece de la Cruz F ，Lennerz JK ，Raghavan S ，Leschiner I ，Elagina L ，Siravegna G ，Ng RWS ，Vu P ，Patra KC ，Saha SK ，Uppot RN ，Arellano R ，Reyes S ，Sagara T ，Otsuki S ，Nadres B ，Shahzade HA ，Dey-Guha I ，Fetter IJ ，Baiev I ，Van Seventer EE ，Murphy JE ，Ferrone CR ，Tanabe KK ，Deshpande V ，Harding JJ ，Yaeger R ，Kelley RK ，Bardelli A ，Iafrate AJ ，Hahn WC ，Benes CH ，Ting DT ，Hirai H ，Getz G ，Juric D ，Zhu AX ，Corcoran RB ，Bardeesy N ... -  《-》

Combination therapies for targeting FGFR2 fusions in cholangiocarcinoma.

Fibroblast growth factor receptor 2 (FGFR2) fusion proteins (FFs) are oncogenic drivers in 10-15% of intrahepatic cholangiocarcinoma (iCCA). FGFR-specific inhibitors provide temporary benefit in FF+ unresectable patients. Recent work with mouse iCCA models has documented the necessary role of RAS-ERK downstream to FFs and provided examples of preclinical experimentation aimed at improving FF targeting in iCCA.

Saborowski A ，Vogel A ，Segatto O 《-》