Fibroblast Growth Factor Receptor Aberrations Research Articles

A selective Fibroblast Growth Factor Receptor 1/2 PROTAC degrader with antitumor activity.

The aberrant activation of fibroblast growth factor receptor (FGFR) acts as a potent driver of multiple types of human cancers. Despite the development of several conventional small-molecular FGFR inhibitors, their clinical efficacy is largely compromised due to low selectivity and side effects. Here, we report the selective FGFR1/2-targeting proteolysis targeting chimeric (PROTAC), BR-cpd7 that displays significant isoform specificity to FGFR1/2 with DC50 values around 10 nM, while sparing FGFR3. The following mechanistic investigation reveals the reduced FGFR signaling, through which BR-cpd7 induces cell cycle arrest and consequently blocks the proliferation of multiple FGFR1/2-dependent tumor cells. Importantly, BR-cpd7 has almost no anti-proliferative activity against cancer cells without FGFR aberrations, furtherly supporting its selectivity. In vivo, BR-cpd7 exhibits robust antitumor effects in FGFR1-dependent lung cancer at well-tolerated dose schedules, accompanied by complete FGFR1 depletion. Overall, we identify BR-cpd7 as a promising candidate for developing a selective FGFR1/2-targeted agent, thereby offering a new therapeutic strategy for human cancers in which FGFR1/2 plays a critical role.

Futibatinib (Lytgobi®)

Futibatinib (Lytgobi®)

LGG-14. TREATMENT OF TWO PEDIATRIC FGFR-ALTERED LOW-GRADE GLIONEURONAL TUMORS WITH MEK INHIBITION

Abstract Somatic alterations in the fibroblast growth factor receptor (FGFR) gene family (FGFR1/2/3) have been implicated in tumorigenesis across pediatric low-grade glioneuronal neoplasms and represent a potential therapeutic target. FGFR rearrangements and internal tandem duplication (ITD) cause constitutive receptor tyrosine kinase activation, thereby promoting tumor cell growth, differentiation, and survival through complex downstream signaling, including via the mitogen activated protein kinase (MAPK) pathway. With increasing safety and efficacy data in pediatric neuro-oncology, MEK inhibitors may be considered to target MAPK pathway activation in FGFR-altered low-grade glioneuronal tumors, although clinical evidence within this specific molecular subgroup is lacking. Herein, we describe two cases of pediatric low-grade glioneuronal tumors harboring FGFR aberrations with encouraging clinical and radiographic response to MEK inhibition. The first patient has a multiply recurrent left parietal dysembryoplastic neuroepithelial tumor (DNET) with an FGFR1 ITD, diagnosed at eight years of age after presenting with seizures. Despite two surgical resections (with identical pathology), his disease slowly progressed. Oral MEK inhibitor therapy with trametinib was initiated, which he has remained on for the past 9+ months, with stable residual tumor without continued radiographic progression. The second patient was diagnosed at three years of age with focal epilepsy, prompting imaging demonstrating an infiltrative T2/FLAIR-hyperintense right temporal mass. Subtotal resection was performed, with pathology consistent with pediatric-type diffuse low-grade glioma. Molecular profiling identified an FGFR3-TACC3 fusion, with suspected enrichment for MAPK-pathway activation by preliminary RNA-sequencing analyses. Adjuvant therapy with trametinib was started, with small reduction in residual disease burden observed radiographically three months into treatment. Both patients continue on MEK inhibitor therapy with minimal toxicity and adequate control of underlying seizures. Though further research in larger, prospective cohorts with comprehensive biology data is necessary, oral MEK inhibitors represent a feasible and rational treatment consideration for pediatric FGFR-altered low-grade glioneuronal tumors.

Characterization of the cholangiocarcinoma drug pemigatinib against FGFR gatekeeper mutants

Fibroblast growth factor receptor (FGFR) dysregulation is involved in a variety of tumorigenesis and development. Cholangiocarcinoma is closely related with FGFR aberrations, and pemigatinib is the first drug approved to target FGFR for the treatment of cholangiocarcinoma. Herein, we undertake biochemical and structural analysis on pemigatinib against FGFRs as well as gatekeeper mutations. The results show that pemigatinib is a potent and selective FGFR1–3 inhibitor. The extensive network of hydrogen bonds and van der Waals contacts found in the FGFR1-pemigatinib binding mode accounts for the high potency. Pemigatinib also has excellent potency against the Val-to-Ile gatekeeper mutation but less potency against the Val-to-Met/Phe gatekeeper mutation in FGFR. Taken together, the inhibitory and structural profiles exemplified by pemigatinib may help to thwart Val-to-Ile gatekeeper mutation-based resistance at earlier administration and to advance the further design and improvement for inhibitors toward FGFRs with gatekeeper mutations.

Fibroblast Growth Factor Receptor 1-4 Genetic Aberrations as Clinically Relevant Biomarkers in Squamous Cell Lung Cancer.

Fibroblast growth factor receptor (FGFR) inhibitors (FGFRis) are a potential therapeutic option for squamous non-small cell lung cancer (Sq-NSCLC). Because appropriate patient selection is needed for targeted therapy, molecular profiling is key to discovering candidate biomarker(s). Multiple FGFR aberrations are present in Sq-NSCLC tumors—alterations (mutations and fusions), amplification and mRNA/protein overexpression—but their predictive potential is unclear. Although FGFR1 amplification reliability was unsatisfactory, FGFR mRNA overexpression, mutations, and fusions are promising. However, currently their discriminatory power is insufficient, and the available clinical data are from small groups of Sq-NSCLC patients. Here, we focus on FGFR aberrations as predictive biomarkers for FGFR-targeting agents in Sq-NSCLC. Known and suggested molecular determinants of FGFRi resistance are also discussed.

Abstract P238: Derazantinib, an inhibitor of fibroblast growth factor receptors 1-3, synergises with paclitaxel in pre-clinical gastric tumor models

Abstract Background: Derazantinib (DZB) is an oral fibroblast growth factor receptor (FGFR) inhibitor with clinical activity in intrahepatic cholangiocarcinoma. Kinase assays indicate activity against other important targets in oncology, including CSF1R and VEGFR2. We have shown that DZB can inhibit phosphorylation of CSF1R upon ligand stimulation in mouse macrophages ex vivo (GI50=100 nM); suggesting tumor-associated macrophages (TAMs) as an important target for DZB. Paclitaxel also reduces M2-TAM function, suggesting a potential synergy when combined with DZB. DZB monotherapy showed strong efficacy in some gastric (GA) PDX tumor models, so we have investigated the combination of DZB and paclitaxel in several GA-models in vivo. Materials and Methods: Four human tumor GA cell lines were studied in vitro: SNU-16, Fu97, AGS and KATOIII. SNU-16 (FGFR2-fusion) was grown s.c. in Balb/c mice as a xenograft (CDX), and 5 different patient-derived xenografts (PDX) with various FGFR-aberrations (fusion, amplification, over-expression or mutation) were grown in the same host. Mice were treated with different doses of DZB (p.o., qd) alone, and/or with paclitaxel (15 mg/kg, i.v., qw) for 3-4 weeks when tumors were 150 mm3. At the endpoint, tumors were ablated and snap-frozen or paraffin-embedded (FFPE) for western-blot/qPCR or immunohistochemistry (IHC), respectively. Efficacy was summarized as the endpoint dT/C, and the interaction assessed formally as synergy/additivity/antagonism by the Clarke-Combination-Index (CCI). The statistical significance of M2-TAMs was assessed using a one-tailed Fisher contingency test. The tumor models were run by CrownBio Inc, which also provided data on the FGFR-aberrations. Results: In vitro, DZB showed synergy with paclitaxel in SNU-16 and Fu97 models at concentrations known to be achievable in mouse plasma. In vivo, three experiments with the SNU-16 model showed reproducible synergy (mean CCI = -0.64) with the combination causing at least stasis and some complete-regressions. A PD-study after 3-days treatment showed a significant decrease in Ki67 and increase in the M1-TAMs in the combination group. Plasma PK showed no indication of a drug-drug interaction between the two compounds. In the 5 PDX-models, the combination showed synergy in three models and additivity in two. IHC analysis of M2-TAM levels in vehicle-treated mice of all 6 models showed that the two additive models had M2-TAM levels ≤0.8%, while synergy was seen in the 4 models with M2-TAMs of 1.1-8.7%. (p=0.03, using a cut-off of 1%). Conclusions: DZB combined with paclitaxel in vivo showed synergy/additivity in GA-tumor models with FGFR aberrations including FGFR2-fusions/amplifications, and FGFR1-3 over-expression or mutations. Additionally, the number of M2-TAMs may also play a role in sensitivity to the combination, which is consistent with the CSF1R kinase being an important target for DZB. Citation Format: Paul M. McSheehy, Mahmoud El Shemerly, Felix Bachmann, Laurenz Kellenberger, Heidi Lane. Derazantinib, an inhibitor of fibroblast growth factor receptors 1-3, synergises with paclitaxel in pre-clinical gastric tumor models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P238.

A Phase 2 Study of Futibatinib (TAS-120) in Patients with Myeloid or Lymphoid Neoplasms Harboring Fibroblast Growth Factor Receptor (FGFR) 1 Rearrangements

▪Background: Myeloid and lymphoid neoplasms (MLNs) with FGFR1 rearrangements are very rare but aggressive myeloproliferative malignancies, characterized by eosinophilia, lymphoid aggregates, and often myelofibrosis, and are recognized as a distinct disease group by the World Health Organization (WHO). In these neoplasms, FGFR1 rearrangements drive oncogenesis via dysregulation of downstream FGFR signaling. Allogenic hematological stem cell transplant (HSCT) is the recommended treatment for patients with FGFR1-rearranged MLNs, as these malignancies are often refractory to chemotherapy and tyrosine kinase inhibitors. Currently, no effective molecularly targeted treatments are available for these patients. Futibatinib is an oral, highly selective, irreversible inhibitor of FGFR1-4 that has shown antitumor activity against FGFR-deregulated tumors in preclinical experiments and in phase 1 studies. Recent results from a phase 2 study demonstrated the efficacy (42% objective response rate) and manageable safety of futibatinib in patients with FGFR2 fusion/rearrangement-positive intrahepatic cholangiocarcinoma. In addition to cholangiocarcinoma, futibatinib treatment resulted in objective responses across tumor types harboring various FGFR aberrations in the phase 1 study. In a separate report, a patient with an FGFR1-driven myeloid neoplasm treated with futibatinib achieved complete hematologic and cytogenetic remission. Based on these data, a multicohort phase 2 study (NCT04189445) was designed to evaluate the efficacy and safety of futibatinib in patients with tumors harboring specific FGFR aberrations. Here, we describe the cohort of patients with MLNs harboring FGFR1 rearrangements.Study Design and Methods: In this global, open-label, multicohort phase 2 study, patients (≥18 years, with Eastern Cooperative Oncology Group performance status 0-1 and adequate organ function) will be enrolled into 1 of 3 cohorts by type of tumor and/or FGFR aberration. The cohort of patients with MLNs harboring FGFR1 rearrangements (as defined by WHO criteria) will include patients who are not candidates for HSCT or other therapies or who have disease progression following HSCT. Patients with clinically significant alterations in calcium-phosphorus homeostasis, ectopic mineralization/calcification, clinically significant retinal/corneal disorder, untreated or clinically/radiologically unstable brain metastases, or prior FGFR inhibitor treatment will be excluded. Approximately 20 patients will be enrolled in this cohort (sample size considerations based on differentiating a ≤10% historical control complete response [CR] rate with a 50% target CR rate with 95% power). Patients will receive futibatinib 20 mg once daily in a continuous 28-day cycle until disease progression, unacceptable toxicity, or other discontinuation criterion is met. The primary endpoint is CR rate. Secondary endpoints include objective response rate, CR with incomplete hematological recovery (CRi) rate, complete or partial cytogenetic response rate, and safety. Additional secondary endpoints are duration of CR, CR+CRi, and response; as well as event-free (leukemia presentation only), progression-free, relapse-free, and overall survival. The study was initiated in August 2020, and patient enrollment is ongoing. DisclosuresKiladjian: AOP Orphan: Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Taiho Oncology, Inc.: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; PharmaEssentia: Other: Personal fees; AbbVie: Membership on an entity's Board of Directors or advisory committees. Shitara: Lilly, Ono Pharmaceutical, Dainippon Sumitomo Pharma, MSD, Daiichi Sankyo, Taiho Pharmaceutical, Chugai Pharm, Astellas Pharm, Medi Science, Eisai, Taiho Oncology: Research Funding; Astellas Pharma, Lilly, Bristol-Myers Squibb, Takeda, Pfizer, Ono Pharmaceutical, Taiho, MSD, Novartis, Abbvie, GlaxoSmithKline, Daiichi Sankyo, Amgen, Boehringer Ingelheim: Consultancy; Novartis, Abbvie, Yakult: Other: Speaker fee. Rosen: Taiho Oncology: Research Funding. Rha: Taiho Oncology, Inc.: Research Funding. He: Taiho Oncology, Inc.: Research Funding. Oh: Taiho Oncology, Inc.: Research Funding; AstraZeneca, Novartis, Array, Eli Lilly, Servier, BeiGene, MSD, Handok: Other: Grants or contracts from any entity; AstraZeneca, Novartis, Genentech/Roche, Merck Serono, Bayer, Taiho, ASLAN, Halozyme, Zymeworks, BMS/Celgene, BeiGene, Basilea, Turning Point: Other: Participation on a data safety monitoring board or advisory board. Melisi: Taiho Oncology, Inc.: Research Funding. Iwasa: Taiho Oncology, Inc.: Honoraria, Research Funding. Jiang: Taiho Oncology, Inc.: Research Funding. Liu: Taiho Oncology, Inc.: Current Employment. Takahashi: Taiho Oncology, Inc.: Current Employment. Ribrag: Roche: Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Membership on an entity's Board of Directors or advisory committees; MSD Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; GSK: Research Funding; PharmaMar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Nanostring: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Astex Pharmaceuticals: Research Funding; Infinity Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Argen-X: Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Epizyme: Honoraria, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees.

P53.03 The Characteristics of FGFR Genetic Aberrations in Chinese Lung Cancer Patients

There are more than a dozen fibroblast growth factor receptor (FGFR) inhibitors in a variety of cancer types in development, including lung cancer. The frequency and types of FGFR aberrations in Chinese NSCLC patients may have great value for clinical therapeutic application.

Targeting the Fibroblast Growth Factor Receptor (FGFR) Family in Lung Cancer.

Lung cancer is the most common cause of cancer-related deaths globally. Genetic alterations, such as amplifications, mutations and translocations in the fibroblast growth factor receptor (FGFR) family have been found in non-small cell lung cancer (NSCLC) where they have a role in cancer initiation and progression. FGFR aberrations have also been identified as key compensatory bypass mechanisms of resistance to targeted therapy against mutant epidermal growth factor receptor (EGFR) and mutant Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) in lung cancer. Targeting FGFR is, therefore, of clinical relevance for this cancer type, and several selective and nonselective FGFR inhibitors have been developed in recent years. Despite promising preclinical data, clinical trials have largely shown low efficacy of these agents in lung cancer patients with FGFR alterations. Preclinical studies have highlighted the emergence of multiple intrinsic and acquired resistance mechanisms to FGFR tyrosine kinase inhibitors, which include on-target FGFR gatekeeper mutations and activation of bypass signalling pathways and alternative receptor tyrosine kinases. Here, we review the landscape of FGFR aberrations in lung cancer and the array of targeted therapies under clinical evaluation. We also discuss the current understanding of the mechanisms of resistance to FGFR-targeting compounds and therapeutic strategies to circumvent resistance. Finally, we highlight our perspectives on the development of new biomarkers for stratification and prediction of FGFR inhibitor response to enable personalisation of treatment in patients with lung cancer.

Targeting FGFR in non-small cell lung cancer: implications from the landscape of clinically actionable aberrations of FGFR kinases.

Objective:Dysfunction in fibroblast growth factor receptor (FGFR) signaling has been reported in diverse cancer types, including non-small cell lung cancer (NSCLC). The frequency of FGFR aberrations in Chinese NSCLC patients is therefore of great clinical significance.Methods:A total of 10,966 NSCLC patients whose tumor specimen and/or circulating cell-free DNA (cfDNA) underwent hybridization capture-based next-generation sequencing were reviewed. Patients’ clinical characteristics and treatment histories were also evaluated.Results:FGFR aberrations, including mutations, fusions, and gene amplifications, were detected in 1.9% (210/10,966) of the population. FGFR abnormalities were more frequently observed in lung squamous cell carcinomas (6.8%, 65/954) than lung adenocarcinomas (1.3%, 128/9,596). FGFR oncogenic mutations were identified in 19 patients (∼0.17%), of which, 68% were male lung squamous cell carcinoma patients. Eleven out of the 19 patients (58%) had concurrent altered PI3K signaling, thus highlighting a potential combination therapeutic strategy of dual-targeting FGFR and PI3K signaling in such patients. Furthermore, FGFR fusions retaining the intact kinase domain were identified in 12 patients (0.11%), including 9 FGFR3-TACC3, 1 FGFR2-INA, 1 novel FGFR4-RAPGEFL1, and 1 novel fusion between the FGFR1 and SLC20A2 5′-untranslated regions, which may have caused FGFR1 overexpressions. Concomitant EGFR mutations or amplifications were observed in 6 patients, and 4 patients received anti-EGFR inhibitors, in whom FGFR fusions may have mediated resistance to anti-EGFR therapies. FGFR amplification was detected in 24 patients, with the majority being FGFR1 amplifications. Importantly, FGFR oncogenic mutations, fusions, and gene amplifications were almost always mutually exclusive events.Conclusions:We report the prevalence of FGFR anomalies in a large NSCLC population, including mutations, gene amplifications, and novel FGFR fusions.

A comprehensive pan-cancer study of fibroblast growth factor receptor aberrations in Chinese cancer patients.

BackgroundThe prevalence and types of fibroblast growth factor receptor (FGFR) mutations vary significantly among different ethnic groups. The optimal application of FGFR inhibitors depends on these variations being comprehensively understood. However, such an analysis has yet to be conducted in Chinese patients.MethodsWe retrospectively screened the genomic profiling results of 10,582 Chinese cancer patients across 16 cancer types to investigate the frequency and distribution of FGFR aberrations.ResultsFGFR aberrations were identified in 745 patients, equating to an overall prevalence of 7.0%. A majority of the aberrations occurred on FGFR1 (56.8%), which was followed by FGFR3 (17.7%), FGFR2 (14.4%), and FGFR4 (2.8%). Further, 8.5% of patients had aberrations of more than 1 FGFR gene. The most common types of aberrations were amplification (53.7%), other mutations (38.8%), and fusions (5.6%). FGFR fusion and amplification occurred concurrently in 1.9% of the patients. FGFR aberrations were detected in 12 of the 16 cancers, with the highest prevalence belonging to colorectal cancer (CRC) (31%). Other FGFR-aberrant cancer types included stomach (16.8%), breast (14.3%), and esophageal (12.7%) cancer. Breast tumors were also more likely than other cancer types to have concurrent FGFR rearrangements and amplifications (P<0.001). In comparison with the public dataset, our cohort had a significantly higher number of FGFR aberrations in colorectal (P<0.001) and breast cancer (P=0.05).ConclusionsAmong the Chinese cancer patients in our study, the overall prevalence of FGFR aberrations was 7.0%. FGFR1 amplification was the most common genetic alteration in CRC, breast cancer, and lung cancer; while FGFR2 amplification was more commonly observed in gastric cancer than in other cancers in our cohort. Our study advances the understanding of the distribution of FGFR aberrations in various cancer types in the Chinese population, which will facilitate the further development of FGFR inhibitors.

Abstract 661: Synergistic antitumor activity of futibatinib, an FGFR1-4 inhibitor, and TAS-117, a selective AKT inhibitor, in FGFR-deregulated cancer models

Abstract Background: TAS-117 is a potent oral allosteric non-ATP inhibitor selective for AKT. A phase 1 study with TAS-117 is ongoing in patients with endometrial cancer and ovarian clear cell carcinoma. Futibatinib (TAS-120) is a selective, irreversible small-molecule fibroblast growth factor receptor (FGFR) 1-4 inhibitor, with potent antiproliferative activity in preclinical models with FGFR aberrations. Phase 2 studies are ongoing in patients with various FGFR-deregulated cancers. We evaluated the antitumor activity of futibatinib plus TAS-117 in FGFR-aberrant cancer models. Methods: Effects of futibatinib plus TAS-117 were investigated in human endometrial FGFR2-N549K-mutated AN3CA cancer cells and small-cell lung cancer FGFR1-amplified DMS114 cells. Activation of RAS and PI3K pathways was assessed by detecting phosphorylation of ERK1/2, AKT, and S6. Antitumor combination indices (CI) for cell viability over time were determined with the Chou-Talalay median-effect method and CalcuSyn software; a CI&amp;lt;0.9 indicates synergy. Antitumor effects of futibatinib (15 mg/kg/d) plus TAS-117 (4 or 8 mg/kg/d) or monotherapy were also evaluated in a mouse AN3CA xenograft model. FGFR signaling, apoptosis (via caspase activity and PARP cleavage), and relative tumor volume (RTV; compared with Day 0) were assessed. Results: Futibatinib and TAS-117 synergistically increased cell death and decreased cell growth in AN3CA (CI&amp;lt;0.40) and DMS114 (CI&amp;lt;0.40) cells, respectively. Apoptosis induction was readily detected with futibatinib plus TAS-117 in AN3CA cells, but low activity was observed with monotherapy. In both AN3CA and DMS114 cells, futibatinib suppressed ERK1/2, but not AKT phosphorylation; the futibatinib plus TAS-117 combination suppressed phosphorylation of both ERK1/2 and AKT. In AN3CA xenografts, combination therapy inhibited the FGFR, PI3K, and MEK pathways. Futibatinib plus TAS-117 increased PARP cleavage more than monotherapy. Compared with Day 0, RTV on Day 15 was 60.71 in the control, 13.40 with futibatinib monotherapy, and 33.63 with TAS-117 (8 mg/kg/d) monotherapy. Treatment with 3 different futibatinib plus TAS-117 combination dosing regimens resulted in marked reductions in RTVs on Day 15 (2.16, 0.53, and 0.22). Conclusions: Our findings suggest that futibatinib plus TAS-117 has synergistic antitumor effects in FGFR-aberrant tumors. A phase 1/2 study of this combination in advanced solid tumors (JapicCTI-194864) is ongoing. Citation Format: Junya Iwasaki, Takuya Kuramoto, Toshiharu Komori, Hitoshi Saito, Hiroshi Hirai. Synergistic antitumor activity of futibatinib, an FGFR1-4 inhibitor, and TAS-117, a selective AKT inhibitor, in FGFR-deregulated cancer models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 661.

Abstract 745: Landscape of FGFRactivating aberrations in Chinese non-small cell lung cancer

Abstract Background Dysfunction in fibroblast growth factor receptor (FGFR) signaling has been reported in non-small cell lung cancer (NSCLC), particularly in lung squamous cell carcinoma (LUSC). We hereby assessed the frequency of FGFR aberrations in a large Chinese NSCLC population. Methods A total of 10,966 NSCLCs whose tumor specimen and/or circulating cell-free DNA (cfDNA) underwent hybridization capture-based next-generation sequencing (NGS) of 400+ cancer-related genes were retrospectively reviewed. Patients' clinical characteristics and treatment histories were further evaluated. Results FGFR aberrations, including mutations, fusions, and gene amplifications, were detected in approximately 1.9% (210/10,966) of the population. FGFR abnormalities were more frequently observed in LUSCs (6.8%, 65/954) than lung adenocarcinomas (1.3%, 128/9596). Previously reported FGFR oncogenic mutations were identified in 19 patients (~0.17%), of which, 68% were male LUSC patients. Eleven out of the 19 patients (58%) had concurrent altered PI3K signaling, thus, highlighting an intriguing molecular characteristic and potential combination therapeutic strategy of dual-targeting FGFR and PI3K signaling in those patients. Furthermore, FGFR fusions retaining the intact kinase domain were identified in 12 patients (0.11%), including nine FGFR3-TACC3 cases, one FGFR2-INA fusion, one novel FGFR4-RAPGEFL1 rearrangement event, and one novel gene fusion between FGFR1 and the SLC20A2 5'-untranslated region, which may result in FGFR1 overexpression. Concomitant EGFR mutations or EGFR amplifications were observed in six patients, four of whom were previously treated with EGFR tyrosine kinase inhibitors, suggesting that FGFR fusions may act as acquired resistance to anti-EGFR therapies. In addition, FGFR amplification was detected in 24 patients, with FGFR1 amplification being the most common event. Notably, FGFR oncogenic mutations, fusions, and gene amplifications were almost always mutually exclusive events. Conclusion We herein report an incidence of FGFR anomalies in a large Chinese NSCLC population, including mutations, gene amplifications, and previously characterized and novel FGFR fusions involving TACC3, INA, RAPGEFL1, and SLC20A2. Keywords: FGFR, activating mutation, fusion, gene amplification, NSCLC, FGFR inhibitors Citation Format: Zhen Zhou, Zichuan Liu, Qiuxiang Ou, Xue Wu, Xiaonan Wang, Yang Shao, Hongyan Liu, Yu Yang. Landscape of FGFRactivating aberrations in Chinese non-small cell lung cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 745.

Abstract 564: Futibatinib (TAS-120) plus chemotherapy demonstrates a synergistic effect across various FGFR-deregulated cancer cell lines and xenograft models

Abstract Introduction: Futibatinib, a selective, irreversible fibroblast growth factor receptor (FGFR) 1-4 inhibitor, has antitumor activity in FGFR-deregulated cancer models. The potential synergistic antitumor effects of targeted therapy plus chemotherapy (chemo) was evaluated by combining futibatinib with cytotoxic agents in in vitro and in vivo models. Methods: Gastric, breast, lung, endometrial, and bladder cancer cell lines with various FGFR aberrations were treated with futibatinib and cytotoxic agents (5-FU, paclitaxel, cisplatin, or gemcitabine) individually or in combination. In vitro cytotoxicity of futibatinib was assessed by PARP cleavage activity. Any combination effect on cell growth was determined by the Bliss independence method, combination index (CI; CalcuSyn software), or isobologram analysis. The antitumor effects of futibatinib plus S-1 or paclitaxel and futibatinib plus gemcitabine or cisplatin were evaluated in gastric FGFR2-amplified SNU-16 and endometrial FGFR2-N549K-mutated AN3CA mouse xenograft models, respectively, by measuring relative tumor volume (RTV). Results: A synergistic effect on cell growth inhibition was observed with futibatinib plus chemo in SNU-16 cells (CIs at ED90 were 0.50 [5-FU], 0.71 [paclitaxel], 0.76 [cisplatin], and 0.29 [gemcitabine]). Increased PARP cleavage and decreased cell growth were observed in SNU-16 cells treated with futibatinib plus 5-FU vs monotherapy. Synergized cell growth inhibition occurred in various FGFR-deregulated cancer cell lines. In xenograft models, vs monotherapy, a significant reduction (P&amp;lt;0.01) in RTV occurred with futibatinib plus S-1, paclitaxel (Table), or cisplatin and a numerically greater reduction with futibatinib plus gemcitabine. Table.Relative tumor volume in SNU-16 mouse xenografts treated with futibatinib or paclitaxel or combination therapyTreatment (mg/kg/d)Relative tumor volumeDay 0Day 4Day 8Day 11Day 15Control11.562.373.344.58Futibatinib (5)a11.321.952.773.83Futibatinib (15)a11.211.822.453.16Paclitaxel (60)b10.480.410.410.59Futibatinib + paclitaxel (5 + 60)c10.470.270.170.14Futibatinib + paclitaxel (15 + 60)c10.440.220.120.07aDays 1-14 (oral).bDay 1 (intravenous).cDays 1-14 + Day 1. Conclusions: Futibatinib showed a synergistic antitumor effect in vitro and in vivo when combined with various cytotoxic agents. These data are promising and warrant further investigation. Citation Format: Hiroshi Sootome, Akihiro Miura, Toshiharu Komori, Hiroshi Hirai. Futibatinib (TAS-120) plus chemotherapy demonstrates a synergistic effect across various FGFR-deregulated cancer cell lines and xenograft models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 564.

INCB054828 (pemigatinib), a potent and selective inhibitor of fibroblast growth factor receptors 1, 2, and 3, displays activity against genetically defined tumor models.

Alterations in fibroblast growth factor receptor (FGFR) genes have been identified as potential driver oncogenes. Pharmacological targeting of FGFRs may therefore provide therapeutic benefit to selected cancer patients, and proof-of-concept has been established in early clinical trials of FGFR inhibitors. Here, we present the molecular structure and preclinical characterization of INCB054828 (pemigatinib), a novel, selective inhibitor of FGFR 1, 2, and 3, currently in phase 2 clinical trials. INCB054828 pharmacokinetics and pharmacodynamics were investigated using cell lines and tumor models, and the antitumor effect of oral INCB054828 was investigated using xenograft tumor models with genetic alterations in FGFR1, 2, or 3. Enzymatic assays with recombinant human FGFR kinases showed potent inhibition of FGFR1, 2, and 3 by INCB054828 (half maximal inhibitory concentration [IC50] 0.4, 0.5, and 1.0 nM, respectively) with weaker activity against FGFR4 (IC50 30 nM). INCB054828 selectively inhibited growth of tumor cell lines with activation of FGFR signaling compared with cell lines lacking FGFR aberrations. The preclinical pharmacokinetic profile suggests target inhibition is achievable by INCB054828 in vivo with low oral doses. INCB054828 suppressed the growth of xenografted tumor models with FGFR1, 2, or 3 alterations as monotherapy, and the combination of INCB054828 with cisplatin provided significant benefit over either single agent, with an acceptable tolerability. The preclinical data presented for INCB054828, together with preliminary clinical observations, support continued investigation in patients with FGFR alterations, such as fusions and activating mutations.

FGFR aberrations increase the risk of brain metastases and predict poor prognosis in metastatic breast cancer patients.

Background:The survival status of patients with breast cancer and brain metastasis (BCBM) receiving current treatments is poor.Method:We designed a real-world study to investigate using patients’ clinical and genetic aberrations to forecast the prognoses of BCBM patients. We recruited 146 BCBM patients and analyzed their clinical features to evaluate the overall survival (OS). For genetic testing, 30 BCBM and 165 non-brain-metastatic (BM) metastatic breast cancer (MBC) patients from Hunan Cancer Hospital, and 86 BCBM and 1416 non-BM MBC patients from the Geneplus database who received circulating tumor DNA testing, were compared and analyzed.Results:Ki67 >14% and >3 metastatic brain tumors were significant risk factors associated with poor OS, while chemotherapy and brain radiotherapy were beneficial factors for better OS. Compared with non-BM MBC patients, BCBM patients had more fibroblast growth factor receptor (FGFR) aberrations. The combination of FGFR, TP53 and FLT1 aberrations plus immunohistochemistry HER2-positive were associated with an increased risk of brain metastasis (AUC = 77.13%). FGFR aberration alone was not only a predictive factor (AUC = 67.90%), but also a significant risk factor for poor progression-free survival (Logrank p = 0.029). FGFR1 aberration was more frequent than other FGFR family genes in BCBM patients, and FGFR1 aberration was significantly higher in BCBM patients than non-BM MBC patients. Most FGFR1-amplified MBC patients progressed within 3 months of the late-line (>2 lines) treatment.Conclusion:A group of genetic events, including FGFR, TP53 and FLT1 genetic aberrations, and HER2-positivity, forecasted the occurrence of BM in breast cancers. FGFR genetic aberration alone predicted poor prognosis.

FGFR Aberrations Increase the Risk of Brain Metastases and Predict Drug Resistance in Metastatic Breast Cancer Patients

The survival status of patients with breast cancer with brain metastases (BCBM) receiving current treatments is poor. We designed a real-world study to investigate patient clinical and genetic aberrations to determine appropriate treatment regimens and forecast the prognoses of BCBM patients. 146 BCBM patients were recruited and their clinical features were analyzed for evaluating overall survival (OS). For genetic testing, 30 BCBM and 165 non-BM BC patients from Hunan Cancer Hospital, and 86 BCBM and 1416 non-BM BC patients from Geneplus database received ctDNA testing was compared and analyzed. Ki67 >14% and >3 metastatic brain tumors were significant risk factors associated with poor OS, while chemotherapy and brain radiotherapy were beneficial factors for better OS. Compared with non-BM metastatic breast cancer (MBC) patients, BCBM patients had significantly more fibroblast growth factor receptor (FGFR) aberrations. The combination of FGFR, TP53 and FLT1 aberrations plus immunohistochemisty (IHC) HER2-positive could effectively predict brain metastases (AUC=77.13%). FGFR aberration alone was not only a prediction factor (AUC=67.90%), but also a significant risk factor for poor PFS (Logrank p=0.029). Among FGFR family members, FGFR1 was the most frequent aberration and significantly higher in BMBC patients. Most FGFR1-amplified MBC patients progressed within 3 months. In conclusion, a group of clinical and genetic events, including FGFR, TP53 and FLT1 genetic aberrations, and HER2-positivity, could forecast the occurrence of BM in breast cancers. Moreover, FGFR genetic aberration alone could predict poor prognosis; FGFR aberrations, especially FGFR1 amplification, resulted in drug resistance and disease progression. Funding Statement: Hunan Provincial Health and Sanitation Committee Project No. 2019070 (Recipient: Zhe-Yu Hu); Hunan Provincial Natural Science Youth Foundation Project No.20190988 (Recipient: Zhe-Yu Hu). Declaration of Interests: The authors declare that they have no conflict of interests. Ethics Approval Statement: The study was approved by the Ethics Committee at Hunan Cancer Hospital, the Affiliated Cancer Hospital of Xiangya School of Medicine / Central South University. Patients consented to participate.

Establishment of Risk Prediction Model for Brain Metastasis with Breast Cancer by Using ctDNA Genetic Profile and Clinical Features from Real-World Data

Background: The survival status of patients with breast cancer with brain metastases (BCBM) is not optimistic, thus understanding of the patient clinical and genetic aberrations is critical for offering appropriate treatment regimens and forecasting the prognoses of the BCBM patients. Methods: The trial was designed as a real-world study. 146 BCBM patients were recruited and their clinical features were analyzed for evaluating overall survival (OS). For genetic testing, 30 BCBM and 165 non-BM BC patients from Hunan Cancer Hospital, and 86 BCBM and 1416 non-BM BC patients from Geneplus database received ctDNA testing was compared and analyzed. Results: For 146 BCBM patients, Ki67 >14% and >3 metastatic brain tumors were significant risk factors associated with poor overall survival (OS), while chemotherapy and brain radiotherapy were beneficial factors for better OS. Compared to non-BM metastatic breast cancer (MBC) patients, BCBM patients had significantly more fibroblast growth factor receptor (FGFR) genetic aberrations. The combination of FGFR, TP53 and FLT1 genetic aberrations plus immunohistochemisty (IHC) HER2-positive could effectively predict brain metastases (AUC=77.13%). FGFR aberration alone was not only a prediction factor (AUC=67.90%), but also a significant risk factor for poor PFS in MBC patients (Logrank p=0.029). Among FGFR family members, FGFR1 was the most frequent aberration and significantly higher in BMBC patients. When further evaluating the genetic response of anti-cancer treatment by ctDNA testing, the frequency of FGFR genetic aberrations could be suppressed by capecitabine-based treatment. Conclusion: A group of clinical and genetic events could forecast the occurrence of brain metastases in breast cancers, including FGFR, TP53 and FLT1 genetic aberrations, and IHC HER2-positive. Moreover, FGFR genetic aberration alone could predict poor prognosis. Funding Statement: Development and Reform Commission of Hunan Province (CN) Hunan Key Research Project No. 2018SK2124 (Recipient: Quchang Ouyang); Hunan Provincial Health and Sanitation Committee Project No. 2019070 (Recipient: Zhe-Yu Hu); Hunan Provincial Natural Science Youth Foundation Project No.20190988 (Recipient: Zhe-Yu Hu). Declaration of Interests: The authors declare that they have no conflict of interests. Ethics Approval Statement: The study was approved by the Ethics Committee at Hunan Cancer Hospital, the Affiliated Cancer Hospital of Xiangya School of Medicine/Central South University.

TAS-120 Cancer Target Binding: Defining Reactivity and Revealing the First Fibroblast Growth Factor Receptor 1 (FGFR1) Irreversible Structure.

1-[(3S)-3-[4-Amino-3-[2-(3,5-dimethoxyphenyl)ethynyl]-1H-pyrazolo[3,4-d]pyrimidin-1-yl]-1-pyrrolidinyl]-2-propen-1-one (TAS-120) is an irreversible inhibitor of the fibroblast growth factor receptor (FGFR) family, and is currently under phase I/II clinical trials in patients with confirmed advanced metastatic solid tumours harbouring FGFR aberrations. This inhibitor specifically targets the P-loop of the FGFR tyrosine kinase domain, forming a covalent adduct with a cysteine side chain of the protein. Our mass spectrometry experiments characterise an exceptionally fast chemical reaction in forming the covalent complex. The structural basis of this reactivity is revealed by a sequence of three X-ray crystal structures: a free ligand structure, a reversible FGFR1 structure, and the first reported irreversible FGFR1 adduct structure. We hypothesise that the most significant reactivity feature of TAS-120 is its inherent ability to undertake conformational sampling of the FGFR P-loop. In designing novel covalent FGFR inhibitors, such a phenomenon presents an attractive strategy requiring appropriate positioning of an acrylamide group similarly to that of TAS-120.

Abstract CT121: Phase I dose-escalation study of TAS-120, a highly selective, covalently bound FGFR inhibitor, in patients with advanced solid tumors

Abstract Background: Fibroblast growth factor receptor (FGFR) gene abnormalities are present in hard to treat cholangiocarcinoma (CCA), glioblastoma, and urothelial carcinomas. TAS-120 is a highly potent and selective, covalently bound small-molecule inhibitor of FGFR1-4. This Phase I dose-escalation study investigated the safety, dose-limiting toxicity (DLT), maximum tolerated dose (MTD), and/or recommended Phase II dose (RP2D) of TAS-120 in patients (pts) with advanced solid tumors (NCT02052778). Methods: Pts aged ≥18 years with advanced solid tumors (without FGFR abnormalities in lower doses and with FGFR abnormalities in higher doses) who had failed all standard therapies were enrolled. TAS-120 was administered 3 times a week (QOD; escalating dose levels, 8-200 mg) or once daily (QD; escalating dose levels, 4-24 mg) continuously in 21-day cycles. Primary objective was to evaluate the safety and determine the MTD and/or RP2D of TAS-120; secondary objective was preliminary antitumor activity. Results: Of 86 enrolled pts, 42 were in the 9 QOD cohorts and 44 in the 5 QD cohorts; 34 pts (17 in each cohort) had ≥4 prior lines of anticancer therapy. The most common tumor types were CCA (7 QOD pts [16.7%]; 18 QD pts [40.9%]) and breast cancer (7 QOD pts [16.7%]; 5 QD pts [11.4%]). Grade ≥3 treatment-emergent AEs (TEAEs) were reported in 24 QOD pts (57.1%) and 27 QD pts (61.4%). The most common TEAEs (≥30%) in any of the QOD and QD cohorts were hyperphosphatemia (50.0% and 68.2%), diarrhea (40.5% and 31.8%), nausea (31.0% and 27.3%), dry mouth (33.3% and 25.0%), constipation (26.2% and 38.6%), and anemia (33.3% and 18.2%), respectively. Treatment-related grade ≥3 TEAEs were reported in 10 QOD pts (23.8%) and 17 QD pts (38.6%). The most common treatment-related TEAEs (≥20%) in QOD and QD cohorts were hyperphosphatemia (50.0% and 68.2%), diarrhea (33.3% and 25.0%), and dry mouth (26.2% and 22.7%), respectively. DLTs were reported in 3 of 9 evaluable pts at 24 mg QD (1 each had grade 3 elevated ALT, elevated ALT and AST, blood bilirubin increase) and 1 of 6 evaluable pts at 8 mg QOD (grade 4 creatinine kinase increase). Median treatment duration was 49.0 days (range 8-359) and 68.5 days (range 1-414) in the QOD and QD cohorts, respectively. Stable disease was reported for 22 QOD pts (52.3%) and 20 QD pts (45.4%), with partial response in 3 QD pts (all had CCA with FGFR2 fusions, 2 pts were in 16 mg, and 1 pt in 24 mg cohorts). Based on these data, the MTD and RP2D for TAS-120 is 20 mg QD. Conclusions: In the dose-escalation phase, TAS-120 demonstrated a very tolerable safety profile and preliminary antitumor activity in heavily pretreated pts with CCA harboring FGFR2 fusions. The dose-expansion phase in pts with tumors harboring FGFR aberrations is ongoing and a Phase II study at 20 mg QD will be initiated in CCA pts with FGFR2 fusions. Citation Format: Rastislav Bahleda, Funda Meric-Bernstam, Lipika Goyal, Ben Tran, Helen He, Robert Winkler, Cinta Hierro, Hendrik-Tobias Arkenau. Phase I dose-escalation study of TAS-120, a highly selective, covalently bound FGFR inhibitor, in patients with advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT121.