Mutations In Fibroblast Growth Factor Receptor Research Articles

603TiP Phase II, open-label study of erdafitinib in adult and adolescent patients (pts) with advanced solid tumours harboring fibroblast growth factor receptor (FGFR) gene alterations

The pan-FGFR tyrosine kinase inhibitor erdafitinib is approved by the US Food and Drug Administration for adults with locally advanced or metastatic urothelial carcinoma and susceptible FGFR3/2 alterations who have progressed during or after ≥ 1 line of platinum-containing chemotherapy. FGFR alterations are potential oncogenic drivers that have been reported in many solid tumours in adult and pediatric pts. Because of limited response to standard of care options in patients failing systemic therapy, there is strong rationale to assess the safety and efficacy of erdafitinib in adolescent and adult pts with advanced solid tumours and FGFR alterations. This phase II open-label study (RAGNAR/42756493CAN2002; NCT04083976) will include pts aged ≥ 12 years with histologically confirmed unresectable locally advanced or metastatic solid tumours (except urothelial) harboring predefined FGFR mutations or fusions. Eligibility screening includes molecular screening for FGFR alterations by central or local next-generation sequencing assays and other clinical criteria. Pts will enroll into either a broad panel cohort (BPC) of target FGFR alterations or an exploratory cohort (EC) for FGFR alterations not meeting BPC criteria. ∼280 pts (BPC, n = 240; EC, n = 40) will be enrolled. The primary efficacy end point is overall response rate (ORR) per Independent Review Committee. Secondary end points include investigator-assessed ORR, duration of response, disease control rate, progression-free survival, overall survival, safety, pharmacokinetics, and health-related quality of life. Safety assessments include adverse events, vital signs, electrocardiograms, physical examinations, laboratory tests, performance status assessment, growth assessments in adolescents, and ophthalmologic examination. Starting in December 2019, pts will be enrolled at ∼158 sites in 15 countries. Results of this study will provide efficacy and safety data for erdafitinib across multiple solid tumours with FGFR alterations and evaluate potential benefit of targeting underlying altered biology of FGFR irrespective of tumour histology in adult and adolescent pts. NCT04083976. Writing assistance was provided by Sally Hassan, PhD, of Parexel, and was funded by Janssen Global Services, LLC. Janssen Research & Development, LLC.

Combined in vitro and in silico analyses of FGFR1 variants: genotype-phenotype study in idiopathic hypogonadotropic hypogonadism.

Fibroblast growth factor receptor 1 (FGFR1) is an idiopathic hypogonadotropic hypogonadism (IHH)-associated gene, mutated in approximately 10% of the patients with this condition. Through targeted gene sequencing of 153 males with IHH and 100 healthy controls, we identified 10 mutations in FGFR1 from IHH patients with a frequency of 5.9% in the Chinese population of central China. These included nine missense mutations(NM_023110.2, p.Gly687Arg, p.Ala608Asp, p.Gly348Glu, p.Asn296Ser, p.Gly226Asp, p.Arg209Cys, p.Gly97Arg, p.Val71Met, p.Gly70Arg) and a splicing mutation c.1430 + 1G > T. in vitro and in silico analyses of FGFR1 variants were conducted to study the impact of the identified mutations. Our findings indicated that the splicing mutation dramatically affected premRNA processing, causing exon 10 and 6 nucleotides in the 3' end of exon 9 to be completely skipped. Two variants (p.Gly687Arg and p.Ala608Asp) markedly impaired tyrosine kinase activity, while the other variants had limited impact on the mitogen-activated protein kinase (MAPK) signaling pathway. However, the functional impairment of the mutant receptors was not always consistent with the phenotypes, indicating that FGFR1 mutations might cause IHH in conjunction with other mutant genes. In this study, we expanded the knowledge on the mutation spectrum of FGFR1 in IHH patients and explored the genotype-phenotype relationship.

Abstract B23: FGFR3 mutations and their relation to FGFR3 expression and clinical outcome in a large radical cystectomy cohort: Implications for anti-FGFR3 bladder cancer treatment?

Abstract Objective: Fibroblast growth factor receptor 3 (FGFR3) is a potentially actionable target in bladder cancer (BC). FGFR3 mutations are associated with favorable prognosis in non-muscle invasive (NMI) BC and MIBC. Overexpression of FGFR3 was reported in up to 40% of FGFR3 wild-type MIBC. p53 alterations rarely coincide with FGFR3 mutations. We analyzed FGFR3 mutations and protein-expression of FGFR3 and p53 and assessed their prognostic value in a multicenter, multilaboratory setting. Methods: We included 1,000 cN0M0, chemotherapy-naive patients who underwent radical cystectomy (RC) with pelvic node dissection. Specimens were reviewed by eight uropathologists. At seven laboratories, FGFR3 mutation status was examined using PCR-SNaPshot. p53 and FGFR3 expression were determined by immunohistochemistry (IHC). FGFR3 mutation status, p53 and FGFR3 protein expression were correlated to each other, clinicopathologic parameters, and disease-specific survival (DSS). Results: FGFR3 mutations were found in 107/1,000 RCs (11%), of which 67 were S249C. Overexpression of FGFR3 was found in 279/1,000 (28%) of tumors. p53 overexpression (cut-off>10%) was found in 638/926 (69%) of available cases. Among FGFR3 mutant tumors, 73% had FGFR3 overexpression. Among FGFR3 wild-type tumors, 22% had FGFR3 overexpression. FGFR3 mutations were associated with lower pT-stage (P<0.001), lower grade (G2-WHO 1973) (P<0.001), absence of CIS (P=0.009), pN0 (P<0.001), normal p53 (P<0.001), and prolonged DSS (Plog-rank=0.001). FGFR3 overexpression was associated with lower pT-stage (P<0.001) and G2 (P<0.001) but not with absence of CIS (P=0.860), pN0 (P=0.230), normal p53, (P=0.330) nor prolonged DSS (Plog-rank=0.204). We found no significant difference in DSS for patients with FGFR3 mutant tumors comparing normal vs. overexpression of FGFR3 (Plog-rank=0.444). Furthermore, we also found no significant difference in DSS for patients with FGFR3 wild-type tumors comparing normal vs. overexpression of FGFR3 (Plog-rank=0.754). Conclusions: FGFR3 mutations identified patients with favorable BC with fewer p53 alterations at RC. FGFR3 overexpression was not associated with DSS in patients with FGFR3 wild-type tumors. Our results suggest that FGFR3 mutations (driver effect) have a distinct functional role than FGFR3 overexpression (passenger effect). Hence, patients with FGFR3 mutations may be more likely to benefit from anti-FGFR3 therapy than patients with only overexpression of FGFR3. Citation Format: Bas van Rhijn, Laura Mertens, Roman Mayr, Peter Bostrom, Mirari Marques, Geert van Leenders, Stefanie Gotz, Michiel van der Heijden, Michael Jewett, Francisco Real, Robert Stohr, Alexandre Zlotta, Markus Eckstein, Yanish Soorojebally, Max Burger, Wolfgang Otto, Francois Radvanyi, Damien Pouessel, Theo van der Kwast, Nuria Malats, Arndt Hartmann, Yves Allory, Deric van der Schoot, Ellen Zwarthoff, Tahlita Zuiverloon. FGFR3 mutations and their relation to FGFR3 expression and clinical outcome in a large radical cystectomy cohort: Implications for anti-FGFR3 bladder cancer treatment? [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr B23.

Abstract IA03: Molecular subtypes of bladder cancer: Toward a more granular description of cancer heterogeneity

Abstract Whole-transcriptome mRNA expression profiling studies have established that muscle-invasive bladder cancers (MIBCs) can be subdivided into “basal/squamous” and “luminal” molecular subtypes that are associated with distinct biologic and clinical properties. In general, basal/squamous tumors tend to be more highly enriched in canonical cancer stem cell and epithelial-to-mesenchymal transition (EMT) biomarkers, and perhaps as a consequence, they are associated with advanced stage and metastatic disease at presentation. On the other hand, luminal tumors are enriched with breast cancer luminal biomarkers, peroxisome proliferator activator receptor (PPARG) expression and pathway activation, members of the miR-200 family of EMT repressors, and activating mutations and fusions targeting fibroblast growth factor receptor-3 (FGFR3). Past studies demonstrated that subsets of both basal and luminal MIBCs respond to neoadjuvant chemotherapy as measured by downstaging to <pT2 at cystectomy, although clinical benefit is greatest in patients with basal tumors, perhaps because they are associated with more subclinical metastatic disease. Completed phase II clinical trials employing small-molecule FGFR inhibitors have confirmed that some patients whose tumors contain activating mutations in FGFR3 obtain clinical benefit, confirming that FGFR3 is a viable target in luminal tumors. As the available datasets grow larger, it has become possible to further subdivide the basal/squamous and luminal tumors into additional molecular subtypes. A fraction of basal/squamous tumors lose expression of basal keratins, TP63, and E- and P-cadherins and exhibit molecular features of “complete” EMT. These tumors are similar to claudin-low breast cancers and appear to be more aggressive, exemplified in the observation that patients with claudin-low tumors fail to benefit from neoadjuvant chemotherapy. It appears likely that sarcomatoid tumors represent a phenotypic conversion to the extreme end of the EMT spectrum. Likewise, neuroendocrine and small cell bladder cancers also appear to evolve from basal/squamous tumors via mechanisms that involve combined inactivation of TP53 and RB1. Although the general determinants of basal/squamous molecular heterogeneity appear relatively straightforward, the extent of the heterogeneity that exists in luminal tumors is still emerging. The Lund group's overall dichotemization of luminal tumors into “genomically unstable” and “urothelial” is extremely attractive, but the determinants of heterogeneity within the urothelial tumors await definition. TCGA and the molecular subtypes consensus group identified a small but clinically aggressive luminal subtype that seems somewhat similar to carcinoma in situ (CIS), but precisely how it corresponds to the other luminal subtypes is also unclear. Finally, micropapillary tumors are enriched in luminal biomarkers and overexpression of ERBB2, but their biologic determinants are also unknown. Because non-muscle invasive bladder cancers (NMIBCs) are highly enriched with luminal tumors, it seems likely that the luminal subtypes will become more granular as larger NMIBC datasets are merged with the MIBCs. Citation Format: David J. McConkey, Woonyoung Choi, Colin P.N. Dinney, Arlene Siefker-Radtke, Bogdan Czerniak. Molecular subtypes of bladder cancer: Toward a more granular description of cancer heterogeneity [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr IA03.

Fibroblast Growth Factor Receptor 3 Alteration Status is Associated with Differential Sensitivity to Platinum-based Chemotherapy in Locally Advanced and Metastatic Urothelial Carcinoma

BackgroundAlterations in fibroblast growth factor receptor 3 (FGFR3) occur in ∼15% of muscle-invasive bladder cancers (MIBCs) and metastatic urothelial carcinomas (mUCs). ObjectiveTo determine the association between FGFR3 status and response to platinum-based chemotherapy in patients with MIBC or mUC. Design, setting, and participantsThe authors conducted a retrospective review and comparison of patients having (1) MIBC treated with neoadjuvant chemotherapy (NAC), (2) mUC treated with first-line platinum-based chemotherapy (M1 cohort), and (3) MIBC who were from The Cancer Genome Atlas (TCGA). InterventionPlatinum-based chemotherapy. Outcome measurements and statistical analysisPathologic response, recurrence-free (RFS) or progression-free (PFS) survival, and overall survival (OS) were compared between patients with FGFR3 alteration (FGFR3alt) and those without it (FGFR3wild type [FGFR3wt]) in the three cohorts. Results and limitationsNine of 72 NAC patients (13%) had FGFR3alt, of whom none had pathologic complete response and three had residual non-MIBC (carcinoma in situ, n = 1; pT1, n = 2). FGFR3alt was associated with shorter RFS (hazard ratio, 2.74; p = 0.044) but not OS. Among TCGA patients who underwent adjuvant chemotherapy (n = 74), FGFR3alt patients had shorter RFS as well. Conversely, among chemotherapy-naive TCGA patients, FGFR3alt was associated with longer RFS and OS. In the M1 cohort (FGFR3alt, n = 27; FGFR3wt, n = 81), FGFR3alt was associated with higher rates of pulmonary metastases and nonregional lymphadenopathy. Despite lower response rates among FGFR3alt patients (37% vs 49%; p = 0.056), PFS and OS were not significantly different from FGFR3wt patients. ConclusionsFGFR3 status is associated with lower responses to platinum-based chemotherapy, which may prompt exploration of nonchemotherapeutic approaches for perioperative management of FGFR3alt urothelial cancers. Patient summaryApproximately 15% of bladder cancers harbor mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. Our findings suggest that FGFR3 mutations might be associated with lower responses and shorter time to recurrence among patients with muscle-invasive bladder cancer who received perioperative platinum-based chemotherapy. FGFR3 status does not significantly impact response to chemotherapy among those with metastatic urothelial cancers.

FGFR3 Mutation Status and FGFR3 Expression in a Large Bladder Cancer Cohort Treated by Radical Cystectomy: Implications for Anti-FGFR3 Treatment?†

Fibroblast growth factor receptor 3 (FGFR3) is an actionable target in bladder cancer (BC). FGFR3 mutations are common in noninvasive BC and associated with favorable BC prognosis. Overexpression was reported in up to 40% of FGFR3 wild-type muscle-invasive BC. We analyzed FGFR3 mutations, FGFR3, and p53 protein expression and assessed their prognostic value in a cohort of 1000 chemotherapy-naive radical cystectomy specimens. FGFR3 mutations were found in 11%, FGFR3 overexpression was found in 28%, and p53 overexpression was found in 69% of tumors. Among FGFR3 mutant tumors, 73% had FGFR3 overexpression versus 22% among FGFR3 wild-type tumors. FGFR3 mutations were significantly associated with lower pT stage, tumor grade, absence of carcinoma in situ, pN0, low-level p53, and longer disease-specific survival (DSS). FGFR3 overexpression was associated only with lower pT stage and tumor grade. Moreover, FGFR3 overexpression was not associated with DSS in patients with FGFR3 wild-type tumors. In conclusion, FGFR3 mutations identified patients with favorable BC at cystectomy. Our results suggest that FGFR3 mutations have a driver role and are functionally distinct from FGFR3 overexpression. Hence, patients with FGFR3 mutations would be more likely to benefit from anti-FGFR3 therapy. Ideally, further research is needed to test this hypothesis. Patient summaryOncogenic fibroblast growth factor receptor 3 (FGFR3) mutations are very common in bladder cancer. In this report, we found that these FGFR3 mutations were associated with favorable features and prognosis of bladder cancer compared with patients with FGFR3 overexpressed tumors only. As a consequence, patients with FGFR3 mutant tumors would be more likely to benefit from anti-FGFR3 therapy than patients with FGFR3 protein overexpression only.

1656-P: FGF-21 Receptor Variants Demonstrate Severe Insulin Resistance in a Mouse Model of Insulin Mediated Pseudoacromegaly

Insulin mediated pseduoacromegaly (IMPA) is a rare insulin resistance syndrome characterized by tall stature, acanthosis nigricans, obesity, and acromegaloid features. Subjects with IMPA have normal growth hormone and IGF-1. However, their insulin levels are markedly elevated. To date, no molecular or genetic etiology has been demonstrated as a definitive cause of IMPA. We previously described an adolescent female diagnosed with IMPA. Exome sequencing identified 2 rare, predicted deleterious, variants in Fibroblast Growth Factor Receptor 1 (FGFR1) and beta-Klotho (KLB) which form the receptor for fibroblast growth factor 21 (FGF-21). Due to FGF-21’s role in insulin signaling, we hypothesized that these mutations may be contributing to our proband’s condition. Our study aimed to knock-in these FGFR1/KLB variants into a mouse model using CRISPR/Cas9 gene editing technology. After embryo microinjection, we were able to generate 4 pups mosaic for the missense mutations in FGFR1 or KLB. The resulting founder mice were backcrossed to wild type mice, and then bred to recapitulate the same digenic geneotype found in our adolescent proband with IMPA. When exposed to a high fat diet, double mutant (FGFR1/KLB) mice demonstrate hyperglycemia (158.0 compared to 125.3 mg/dL, p=<0.0001). At 9 weeks-old, the double mutant mice weighed 40.9 g compared to 25.4 g (p=0.0177). These mice underwent a 2 g/kg intraperitoneal glucose tolerance test. While fasting, both the double mutant and wild type mice had normal glucose (87 and 76 mg/dL). However fasting insulin was elevated in the double mutant mice (1246.1 to 231.5 pg/mL). 30 minutes post glucose, the double mutant mice demonstrated hyperglycemia (414 to 274 mg/dL) and marked hyperinsulinemia (2,358.0 to 884.3 pg/mL). Although further characterization of these mice is required, thus far, these studies suggest that our proband’s digenic variants in FGFR1/KLB are likely to be pathogenic and are a potential cause of IMPA. Disclosure S.I. Stone: Research Support; Self; National Institutes of Health. Speaker’s Bureau; Self; Rhythm Pharmaceuticals. T. Lupu: None. F. Urano: Stock/Shareholder; Self; CytRx Corporation. Other Relationship; Self; AETAS Pharma, Amylyx Pharmaceuticals, Mitochon, National Center for Advancing Translational Sciences, Novus Biologicals?. D.M. Ornitz: None. Funding National Institutes of Health (R21HD098872); Washington University (P30DK020579); National Center for Advancing Translational Sciences (UL1TR002345)

MSK-ACCESS for the detection of fibroblast growth factor receptor-3 (FGFR3) mutations in plasma cell-free (cf)DNA of metastatic urothelial carcinoma (mUC) patients (pts) pre- and on erdafitinib (erda) therapy.

e17034 Background: The pan-FGFR inhibitor erda was recently FDA-approved for pretreated mUC pts harboring FGFR2/3 alterations. We explored concordance of FGFR3 mutation profiles between the primary tumor and cfDNA using the MSK-ACCESS platform. We also correlated changes in FGFR3 cfDNA mutant allele fraction (MAF) with response to drug. Methods: Plasma samples were collected from mUC pts started on erda at baseline, on treatment (tx), and at progression. Demographic and clinical characteristics were obtained. Baseline tumors were sequenced with MSK-IMPACT (ref) and plasma samples were sequenced using MSK-ACCESS, a cfDNA platform that sequences 129 genes using unique molecular indexes to generate > 15,000x coverage and detection of somatic mutations down to 0.1% MAF. Results: Between 08/2019-1/2020, 11 pts received erda 8mg daily. Of these, 3 pts increased dose to 9mg daily based on phosphorus level, 4 required dose reductions and 6 dose interruptions. In 5 pts, erda was discontinued for disease progression. FGFR3 S249C was the most frequent alteration detected (64%) followed by Y373C (18%), R248C and S371C (both 9%). Pre-treatment plasma FGFR3 profiles were concordant with tissue in 91% (10/11) of pts and additional FGFR3 mutations were detected in 3 cases (27%, Table), including 1 pt with an FGFR3-TACC3 fusion and hotspot mutations only in cfDNA. In 2 responding pts, the mutant allele was undetectable on erda. Conclusions: A high degree of concordance between primary tumor and cfDNA FGFR3 mutation detection was observed. FGFR3 mutations exclusive to cfDNA were found in a subset of pts. Further pt accrual and follow-up are ongoing to assess for correlations between erda response and tx-related changes in cfDNA MAF, and to assess whether cfDNA can identify resistance mechanisms. [Table: see text]

Safety and efficacy of pemigatinib plus pembrolizumab combination therapy in patients (pts) with advanced malignancies: Results from FIGHT-101, an open-label phase I/II study.

3606 Background: Pemigatinib (INCB054828) is a selective fibroblast growth factor receptor (FGFR) 1–3 inhibitor with demonstrated efficacy as monotherapy in phase 1/2 (FIGHT-101) and phase 2 (FIGHT-201, -202, -203) trials in pts with advanced cancer. Here, we present preliminary safety, efficacy, and pharmacokinetic (PK) data for pemigatinib (PEMI) combined with pembrolizumab (PEMBRO), a programmed cell death protein-1 (PD-1) inhibitor, in pts with refractory advanced malignancies enrolled in the ongoing FIGHT-101 trial (NCT02393248). Methods: FIGHT-101 includes monotherapy (part 1 and 2) and combination therapy (part 3) cohorts. This analysis is based on pts enrolled in the PEMI + PEMBRO combination dose finding (3a) and dose expansion (3b) cohorts. Eligible adults had advanced malignancies who had progressed after prior therapy and for whom PEMBRO treatment was relevant; pts in part 3b had FGF/FGFR alterations. Pts received oral PEMI at 9 mg or 13.5 mg QD on an intermittent dosing (ID) schedule (21-day cycle, 14-day on/7-day off), or 13.5 mg QD on a continuous dosing (CD) schedule, plus PEMBRO 200 mg IV on day 1 of each 21-day cycle. Results: At data cutoff (August 30, 2019), 23 pts had received PEMI + PEMBRO; 22 (96%) had discontinued therapy (disease progression, 70%). Most frequent tumors were NSCLC (n = 3), bladder (n = 3), pancreatic, testicular, and sarcoma (each n = 2). Of 19 enrolled pts with baseline FGF/FGFR data; 5 had FGFR mutations or rearrangements. No dose-limiting toxicities occurred with PEMI + PEMBRO. The recommended PEMI dose combined with PEMBRO was 13.5 mg QD. Most frequent all-cause, all-grade (Gr) adverse events for ID (n = 17) were hyperphosphatemia (n = 14 [82%]; Gr ≥3, n = 0), anemia (n = 9 [53%]; Gr ≥3, n = 3 [18%]), and decreased appetite (n = 9 [53%]; Gr ≥3, n = 0); for CD (n = 6), hyperphosphatemia (n = 5 [83%]; Gr ≥3, n = 0), and dry mouth (n = 4 [67%]; Gr ≥3, n = 0). One pt discontinued, 2 reduced dose, and 13 interrupted dose due to AEs (none for hyperphosphatemia; dose interruption mainly for gastrointestinal AEs [n = 5]). One fatal AE occurred (suicide, not treatment-related). PK parameters for PEMI in the PEMI + PEMBRO combination were comparable with those for PEMI monotherapy. Five pts had partial response (3 had FGFR rearrangements or mutations); 5 pts had stable disease. Conclusions: PEMI + PEMBRO combination therapy was tolerable with no new safety signals, and demonstrated preliminary antitumor activity in pts with advanced malignancies including those with FGF/FGFR alterations. Clinical trial information: NCT02393248 .

SUN-101 Support for a New Therapeutic Approach of Using a Low-Dose FGFR Tyrosine Kinase Inhibitor (Infigratinib) for Achondroplasia

Background: Achondroplasia (ACH) is the most common non-lethal skeletal dysplasia. Fibroblast growth factor receptor 3 (FGFR3) plays a crucial role in bone elongation, demonstrated by FGFR3 gain-of-function mutations in individuals with ACH and hypochondroplasia. Multiple therapeutic strategies have been considered for ACH, the most advanced is to employ an analog of C-type Natriuretic Peptide (CNP), which antagonizes the MAP kinase (MAPK) pathway. Here, we evaluated a therapeutic strategy that targets all pathways downstream of FGFR3 (e.g., STAT1), not just MAPK. We hypothesized that a very low dose of the oral selective FGFR1-3 tyrosine kinase inhibitor (TKI) infigratinib (BGJ398) would be able to improve defective bone elongation. We also hypothesized that infigratinib would have greater potency at lower concentrations in an ACH cell line than a CNP analog (e.g., vosoritide) given its effects on multiple downstream pathways. Methods: A mouse model (Fgfr3Y367C/+) mimicking ACH was treated with subcutaneous injections of infigratinib daily (0.2 or 0.5 mg/kg/day) or intermittently (1 mg/kg, every 3 days) for a treatment duration of 15 days (PND1-15). In vivo results were compared with vehicle-treated mutant mice. TAN 4-18-chondrocytes, a human chondrocyte line expressing a heterozygous Y373C FGFR3 mutation, were treated with multiple concentrations of infigratinib and vosoritide and MAPK levels were measured. Results: We observed a significant improvement of the upper (humerus +7%, ulna +11%) and lower (femur +11%, tibia +16%) limbs at 0.5 mg/kg/day, and improvement in the foramen magnum. The effect of infigratinib on bone elongation was reduced with a lower dose (0.2 mg/kg), confirming a dose-response relationship. With intermittent injections of infigratinib (1 mg/kg, every 3 days), gain of growth was significant for all the long bones (+7%) and the size of the foramen magnum was increased. Modification of the growth plate structure, displaying better organization, was also seen. In cell line data, compared with FGF18-treated TAN 4-18-chondrocytes, concentrations of 10-6M to 10-10M infigratinib led to statistically significant (p<0.05) improvements. With vosoritide treatment, a concentration of 10-4M led to statistically significant improvements compared with FGF18-treated chondrocytes (p<0.05), although this was not seen at 10-5M. Conclusions: Preclinical ACH mouse model data indicate that low, as well as intermittent, doses of infigratinib promote growth and can improve the foramen magnum. No apparent toxicity of infigratinib was observed, suggesting that TKI therapy has the potential to be a valuable and relevant option for children with ACH. Furthermore, cell line data indicate that infigratinib showed superior potency over a CNP analog, suggesting that inhibition of multiple FGFR3-related pathways vs MAPK inhibition alone may lead to increased efficacy.

New developments in the management of achondroplasia

SummaryAchondroplasia is the most common form of disproportionate short stature. A dominantly inherited FGFR3 mutation permanently activates the fibroblast growth factor receptor 3 (FGFR3) and its downstream mitogen-activated protein kinase (MAPK) signalling pathway. This inhibits chondrocyte differentiation and puts a break on growth plate function, in addition to causing serious medical complications such as foramen magnum and spinal stenosis and upper airway narrowing. A great deal has been learned about complications and consequences of FGFR3 activation and management guidance is evolving aimed to reduce the increased mortality and morbidity in this condition, particularly deaths from spinal cord compression and sleep apnoea in infants and small children. To date, no drugs are licensed for treatment of achondroplasia. Here, we report on the various substances in the drug development pipeline which target elements in molecular disease mechanism such as FGF (fibroblast growth factor) ligands, FGFR3, MAPK signalling as well as the C‑type natriuretic peptide receptor NPR‑B (natriuretic peptide receptor B).

Urine cytology suspicious for urothelial carcinoma: Prospective follow-up of cases using cytology and urine biomarker-based ancillary techniques.

Urine cytology results that are suspicious for urothelial carcinoma (UC) are challenging. The objective of this study was to elucidate the clinical significance of such results in patients who have a negative cystoscopy. In this prospective study, 83 patients who had urine cytology that was suspicious of UC and a negative cystoscopy underwent a second cystoscopy and urine evaluation by cytology, UroVysion fluorescence in situ hybridization (FISH) assay, FGFR3 (fibroblast growth factor receptor 3) and TERT (telomerase reverse transcriptase) mutations and an 8-gene expression classifier (GEC). Results from all techniques were compared with patients' clinical outcomes. The presence of tumor was identified in 41% of patients; of these, 82% had tumors identified at their second evaluation (76% high-grade [HG] tumors), and 18% had tumors identified at a later follow-up (50% were HG tumors). After The Paris System for Reporting urinary Cytology (TPS) reclassification, 53 cytology results still had an indeterminate diagnosis (13 were suspicious for HGUC, and 40 had atypical urothelial cells (AUCs)]. Complete results from second evaluations using urine cytology, cytology-TPS, FISH, and GEC were available for 6 cases that were suspicious for HGUC and 34 cases that had AUCs. The sensitivity of these techniques to detect HG tumors in cases that were suspicious for HGUC was 100%, except for cytology-TPS, for which the sensitivity was 50%. The sensitivity of cytology and cytology-TPS to detect HG tumors in cases with AUCs was 33%, whereas the sensitivity of fluorescence in situ hybridization and GEC in these cases was 83% and 75%, respectively, to detect HG tumors at the second evaluation. The current results indicate the relevant clinical significance of indeterminate urine cytology findings and strongly suggest the use of complementary evaluations by urine biomarker-based, ancillary techniques to elucidate their significance.

Comprehensive targeted gene profiling to determine the genomic signature likely to drive progression of high-grade nonmuscle invasive bladder cancer to muscle invasive bladder cancer.

568 Background: Bladder cancer is the fifth most common cancer and eighth leading cause of cancer related-death in North America. It can present as non-muscle invasive bladder cancer (NMIBC) and/or muscle invasive bladder (MIBC). Although genomic profiling studies have established that low-grade NMIBC and MIBC are genetically distinct, high-grade NMIBC can recur and progress to MIBC [ Knowles, M.A. and C.D. Hurst, 2015]. Low grade, non-invasive bladder cancers are characterized by activating mutations in fibroblast growth factor receptor 3 (FGFR3), HRAS or other pathways of receptor kinase activation. High-grade disease, which is often becomes invasive, is characterized by inactivation of TP53 and Rb pathways [Kim, J., et al.]. Finding a subtype of invasive carcinoma with FGFR3 mutation may suggest an alternate pathway by which low grade, non-invasive pathology could transform into invasive disease [Knowles, M.A. and C.D. Hurst, 2015]. Methods: In this study, using a total of 30 bladder cancer (NMIBC and MIBC) patient samples from Windsor Regional Hospital Cancer Program, we performed comprehensive targeted gene sequencing to identify single nucleotide variants, small insertions / deletions, copy number variants and splice variants in over 500 common tumor genes panel. Results: Preliminary data from our study correlates with previously published mutation landscape for NMIBC and MIBC, and includes mutations in EGFR, FGFR3, FGFR4, PIK3CA, CDK6, ALK, JAK, as well as RET. While mutations in AKT1, BRCA1, CCND1, ERBB2, FGFR1, FGFR2, HRAS, and MET appear to be prevalent in NMIBC, mutations in IDH1 and MAP2K2 appear to be more common in MIBC. Three of the samples used in the study are from patients who progressed from high-grade NMIBC to MIBC. Conclusions: Therefore, have the genomic profiling performed at these two stages, which provides a unique ability to identify the potential “genomic triggers” for the transition.

A phase Ib study of alofanib, an allosteric FGFR2 inhibitor, in patients with advanced or metastatic gastric cancer.

TPS466 Background: Fibroblast growth factor receptor 2 (FGFR2) is amplified or overexpressed in 3% to 61% of patients with gastric cancer and associated with a poor prognosis. Acquired mutations in FGFR2 develop resistance to multikinase inhibitors. Besides, resistance to monoclonal antibodies depends on the type of FGFR2 isoforms IIIc or IIIb expressed by cancer cells. Alofanib (RPT835) is a novel selective allosteric inhibitor of FGFR2. Alofanib could bind to the non-active site of FGFR2 extracellular domain and had an inhibitory effect on FGF2-induced phosphorylation of FRS2α. On preclinical models no severe organ and function test changes were observed. Based on these results, alofanib has advanced into clinical evaluation. Methods: RPT835GC1B is a Phase 1b study, being conducted in at least four sites in Russia, evaluating the safety and preliminary efficacy of alofanib in patients with advanced and metastatic gastric adenocarcinoma pretreated with ≥ 1 previous lines of therapy. This trial consists of two parts. The standard dose-escalation part (design 3+3) aims to establish the maximum tolerated dose (MTD) or recommended phase 2 dose (R2PD) as a primary endpoint. The first part of the study includes a 28-day period when alofanib is administered daily intravenously for 5-days followed by a 2-day interval (rest). There are five dose levels: 50, 100, 165, 250, and 350 mg/m2. The dose-expansion phase accrues additional 20 patients, where comprehensive information to be collected. Secondary endpoints include pharmacokinetic parameters, rate of adverse events, progression-free survival, overall survival, and objective response rate. All patients will receive alofanib until disease progression or unacceptable toxicity. FGFR2 amplification, fusion, and overexpression will be assessed as well. Clinical trial information: NCT04071184.

Different FGFS Stimulate FGFR1 in Different Ways

Fibroblast Growth Factor Receptor 1 (FGFR1) is a Receptor Tyrosine Kinase (RTK) that is important for cell proliferation, survival, and motility. It is critical for embryonic skeletal development, and genetic mutations in FGFR1 can result in abnormalities such as Osteoglophonic dysplasia and Pfeiffer Syndrome. FGFR1 is found in the mesoderm of the developing limb bud, while its cognate ligands are expressed in the limb bud ectoderm. It is believed that the ligands can diffuse through the mesoderm to activate the protein. Knockouts in mouse embryos of three specific ligands, Fibroblast Growth Factor (FGF) 4, FGF 8, and FGF 9, alone and combined, all result in distinctive skeletal phenotypes. How FGFR1 can recognize and respond to each unique ligand is currently unclear. The current model postulates that the three ligands are functionally the same, but each ligand has a unique spatial and temporal expression. We have found, however, that the current paradigm is not correct. In fact, each ligand stimulates distinctly different downstream signaling pathways. We proved this by using fluorescence and western blotting to quantitatively study FGFR1 association and FGFR1 signaling in response to the three ligands. The new knowledge about FGF-FGFR interactions, gained here, can change how RTK signaling is viewed and can greatly affect future drug development endeavors.

TERT Promoter Mutation as a Potential Predictive Biomarker in BCG-Treated Bladder Cancer Patients.

Telomerase reverse transcriptase gene promoter (TERTp) mutations are recognized as one of the most frequent genetic events in bladder cancer (BC). No studies have focused on the relevance of TERTp mutations in the specific group of tumors treated with Bacillus Calmette–Guérin (BCG) intravesical therapy. Methods — 125 non muscle invasive BC treated with BCG therapy (BCG-NMIBC) were screened for TERTp mutations, TERT rs2853669 single nucleotide polymorphism, and Fibroblast Growth Factor Receptor 3 (FGFR3) hotspot mutations. Results — TERTp mutations were found in 56.0% of BCG-NMIBC and were not associated with tumor stage or grade. FGFR3 mutations were found in 44.9% of the cases and were not associated with tumor stage or grade nor with TERTp mutations. The TERT rs2853669 single nucleotide polymorphism was associated with tumors of higher grade. The specific c.1-146G>A TERTp mutation was an independent predictor of nonrecurrence after BCG therapy (hazard ratio—0.382; 95% confidence interval—0.150–0.971, p = 0.048). Conclusions — TERTp mutations are frequent in BCG-NMIBC and -146G>A appears to be an independent predictive marker of response to BCG treatment with an impact in recurrence-free survival.

Prenatal diagnosis of fetal thanatophoric dysplasia type 1 with de novo c.2419T &gt; G (p. Ter807Gly) (X807G) gene mutation in fibroblast growth factor receptor 3 (FGFR3) showing increased nuchal translucency at the first trimester of gestation: A case report with review of the literature

Thanatophoric dysplasia (TD) is a rare form of lethal skeletal dysplasia with underdevelopment of skeleton and dwarfism. The femur is curved in subtype 1, and straight in subtype 2 TD. Other characteristics include a narrow chest, small ribs and hypoplastic lungs. TD is due to activating mutations in fibroblast growth factor receptor 3 (FGFR3), which result in increased receptor activation and alterations in the process of endochondral ossification in all long bones. The aim of the present study was to present the perinatal ultasonographic findings at the 1st and 2nd trimester of a pregnancy and the underlying molecular defect in a fetus with TD type 1, due to a rare mutation in the FGFR3 gene. Ultrasonography performed at the 12w2d of gestation showed increased nuchal translucency (NT). Prenatal karyotype was normal for the XX fetus. Ultrasonography at 17 weeks and 5 days of gestation revealed narrow thorax, abdominal protrusion and a decreased rate of development of the femur (Femur Length, FL &lt; 5th percentile). Molecular genetic analysis to exclude possible overlapping syndromes was performed and revealed de novo c.2419T &gt; G (p. Ter807Gly) (X807G) gene mutation in FGFR3. Fetal autopsy confirmed the prenatal prediction of lethality. We conclude that a fetus with a heterozygous c.2419T &gt; G mutation in FGFR3, presented characteristic biometric parameters and ultrasonographic and autopsy findings consistent with the diagnosis of TD type 1. In addition, the combination of ultrasonography, molecular genetic analysis and autopsy is helpful for the appropriate genetic counselling and perinatal management.

MRNA Expression of FGFR1 as Potential Marker for Predicting Prognosis of Surgical Resection of Small Cell Lung Cancer may be better than Protein Expression and Gene Amplification.

Purpose: Fibroblast growth factor receptor 1 (FGFR1) alterations have been described in many cancers, including lung cancer, but the role has not been elucidated specifically in small cell lung cancer (SCLC). The present study aimed to identify the frequency of FGFR1 alterations among Chinese patients with surgically resected SCLC and the association with the clinicopathological characteristics and the survival were also investigated.Methods: FGFR1 protein expression, FGFR1 amplification, FGFR1 mutations, and messenger RNA (mRNA) levels, were determined by immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), polymerase chain reaction (PCR) and reverse transcription-polymerase chain reaction (RT-PCR), respectively in primary tumors from 33 patients with resected SCLC.Results: 7/33(21.2%) of the specimens were positive for FGFR1 protein expression. FGFR1 amplification was identified in 4/28 cases (14.3%). If the cut-off value was determined to be 3.5, FGFR1 mRNA positivity was considered in 7/33 cases (21.2%). However, no mutation was detected in the 33 SCLC postoperative tissue specimens. No significant association was observed between FGFR1 protein expression or amplification and clinicalcharacteristics or prognosis. There was a distinct trend for mRNA level and poor prognosis, including recurrence-free survival (RFS) (p = 0.07) and overall survival (OS) (p= 0.08), but they did not reach statistical significance.Conclusions: As novel FGFR1-targeted therapies are developed, FISH, IHC, especially mRNA were detected, which should be considered as biomarkers of FGFR1 pathway dysregulation in SCLC.

Abstract C071: Pharmacokinetics and pharmacodynamics of pemigatinib, a potent and selective inhibitor of FGFR 1, 2, and 3, in patients with advanced malignancies

Abstract Pemigatinib is a potent inhibitor of fibroblast growth factor receptors (FGFR) 1, 2, and 3 with selectivity against other kinases and is currently being studied in solid tumors expressing FGFR translocations and/or mutations. A first-in-man phase 1 study (FIGHT-101) was conducted in patients with solid tumors who are refractory to approved treatments, to establish the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of pemigatinib. The study was conducted in 3 parts to allow dose escalation, dose expansion, and food-effect and combination treatments, respectively. Both intermittent (2 wks on/1 wk off) and continuous daily dosing were evaluated. A total of 116 patients have received monotherapy and 44 received combination therapy, as of February 19, 2019. Serial blood samples were collected to enable PK/PD analyses, and plasma samples were assayed for pemigatinib by a validated LC-MS/MS method with a linear validated range of 1 to 1000 nM in human plasma. With multiple-dose administration in the fasted state, pemigatinib plasma concentrations attained peak values (Cmax) typically at 1–2 hours (median Tmax) post-dose, and subsequently exhibited a bi-exponential decay, with a steady-state geometric mean terminal-phase disposition half-life (t½) of approximately 15 hours that was not dose-dependent. The geometric mean accumulation ratio was approximately 1.6 for area under the curve from time 0 to 24 hours (AUC0-24). Within the dose range of 1 to 20 mg once daily (QD), increases in the pemigatinib steady-state Cmax and AUC0-24 were proportional to dose; that is, pemigatinib exhibited linear PK over the dose range studied. Pemigatinib exhibited a low steady-state oral clearance with geometric mean of 9.88–11.7 L/h and moderate volume of distribution with geometric mean of 173–244 L. At the recommended part 2 dose of 13.5 mg QD, the geometric mean (CV%) of t½, steady-state Cmax, and AUC0-24 were 15.4 h (51.6%), 236 nM (56.4%), and 2620 h*nM (54.1%), respectively. The PK parameters of pemigatinib following combination therapy were similar to that of monotherapy. Administration of a standardized high-fat and high-calorie breakfast prolonged the median pemigatinib Tmax to 4 hours, decreased the geometric mean steady-state Cmax by 18%, and increased the geometric mean steady-state AUC0-24 by 11%. The 90% CI of geometric mean ratio for steady-state Cmax and AUC0-24 were (0.648–1.03) and (0.935–1.31), respectively. The effect of food on pemigatinib plasma exposures was considered as modest and not clinically meaningful. Therefore, pemigatinib can be administered without regard to food. The geometric mean fraction of pemigatinib excreted in urine was 1.19% (range, 0.226–7.24%) with a geometric mean renal clearance of 0.133 L/h based on exploratory urine excretion data, indicating minor contribution from renal clearance towards total systemic clearance. Hyperphosphatemia is an expected on-target pharmacologic effect of FGFR inhibition. The increase in serum phosphorus observed after treatment with pemigatinib was exposure-dependent and followed a sigmoidal relationship. In conclusion, pemigatinib exhibits rapid absorption, linear PK, and a t½ consistent with QD dosing. Pemigatinib is predominantly cleared by metabolism and there are no active metabolites. Citation Format: Tao Ji, Christine Lihou, Ekaterine Asatiani, Luis Féliz, Heather Overholt, Robert Landman, Xuejun Chen, Swamy Yeleswaram. Pharmacokinetics and pharmacodynamics of pemigatinib, a potent and selective inhibitor of FGFR 1, 2, and 3, in patients with advanced malignancies [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C071. doi:10.1158/1535-7163.TARG-19-C071

Abstract A077: FIGHT-207: Phase 2 study of pemigatinib in patients with previously treated, locally advanced/metastatic or unresectable solid tumor malignancies harboring activating fibroblast growth factor receptor (FGFR) gene alterations

Abstract Introduction: Activating mutations, rearrangements, and amplifications of FGFR, resulting in either ligand-independent or aberrant ligand-dependent FGFR signaling have been identified in many tumor types. A recent large-scale sequencing study across tumor types identified FGFR alterations in 7.1% of cancers, including gene amplification (66%), mutations (26%), and rearrangements (8%) (Helsten CCR 2016). Pemigatinib (INCB054828) is a selective, potent, oral inhibitor of FGFR1–3 that has demonstrated antitumor activity in FGFR-driven tumors in phase 1/2 (FIGHT-101) and phase 2 (FIGHT-201, -202, and -203) studies. FIGHT-207 is a phase 2, open-label, single-arm, tumor-agnostic study that will evaluate the efficacy and safety of pemigatinib monotherapy in patients with advanced/metastatic or surgically unresectable solid tumor malignancies with activating FGFR mutations, fusions or rearrangements (NCT03822117). Methods: Eligible patients (aged ≥18 years) have histologically or cytologically confirmed solid tumor malignancy that is advanced/metastatic or is surgically unresectable; radiographically measurable disease (per Response Evaluation Criteria in Solid Tumors version 1.1 [RECIST v1.1] or Response Assessment in Neuro-Oncology [RANO] for primary brain tumors); documented FGFR1–3 mutation or translocation; objective progression after at least 1 prior therapy, and no therapy available that is likely to provide clinical benefit; Eastern Cooperative Oncology Group performance status 0 to 2; and no prior receipt of a selective FGFR inhibitor. Patients are assigned to 1 of 3 cohorts based on FGFR status: Cohort A (n ~ 60): FGFR1–3 in-frame fusions or FGFR2 intron 17 rearrangements; Cohort B (n ~ 90): known/predicted activating point mutations in FGFR1–3; and Cohort C (n ~ 20): any FGFR1–3 point mutations in the kinase domain, variants of unknown significance or FGFR1/FGFR3 rearrangements without an identified partner gene. All patients receive a starting dose of pemigatinib 13.5 mg once daily on a 21-day cycle. Patients with no grade ≥2 treatment-related adverse events and no hyperphosphatemia (serum phosphate &amp;gt;5.5 mg/dL) during cycle 1 are allowed to increase dose to pemigatinib 18 mg from cycle 2. Treatment continues as long as patients are receiving benefit or until treatment withdrawal criteria are met. Hyperphosphatemia is managed with diet modifications, phosphate binders, and diuretics, or pemigatinib dose reduction/interruption. The primary endpoint is objective response rate (assessed by independent review committee [IRC] per RECIST v1.1 or RANO) in Cohorts A and B. Secondary endpoints are progression-free survival, duration of response, and overall survival in Cohorts A and B; safety and tolerability in all cohorts. Biopsies will be obtained for select tumors at screening, on-treatment, and at end of treatment. Additional biomarkers that may be indicative of clinical response, resistance, and safety may also be investigated. The study is currently recruiting. Citation Format: Luis Féliz, Ekaterine Asatiani, Christine Lihou, Huiling Zhen, Ian Silverman, Jordi Rodon Ahnert. FIGHT-207: Phase 2 study of pemigatinib in patients with previously treated, locally advanced/metastatic or unresectable solid tumor malignancies harboring activating fibroblast growth factor receptor (FGFR) gene alterations [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A077. doi:10.1158/1535-7163.TARG-19-A077