FGFR redundancy limits the efficacy of FGFR4-selective inhibitors in hepatocellular carcinoma.

Aberrant fibroblast growth factor 19 (FGF19) signaling mediated by its receptor, FGF receptor 4 (FGFR4), and coreceptor, klotho ß (KLB), is a driver of hepatocellular carcinoma (HCC). Several potent FGFR4-selective inhibitors have been developed but have exhibited limited efficacy in HCC clinical trials. Here, by using HCC cell line models from the Cancer Cell Line Encyclopedia (CCLE) and the Liver Cancer Model Repository (LIMORE), we show that selective FGFR4 inactivation was not sufficient to inhibit cancer cell proliferation and tumor growth in FGF19-positive HCC. Moreover, genetic inactivation of KLB in these HCC cells resulted in a fitness defect more severe than that resulting from inactivation of FGFR4. By a combination of biochemical and genetic approaches, we found that KLB associated with FGFR3 and FGFR4 to mediate the prosurvival functions of FGF19. KLB mutants defective in interacting with FGFR3 or FGFR4 could not support the growth or survival of HCC cells. Genome-wide CRISPR loss-of-function screening revealed that FGFR3 restricted the activity of FGFR4-selective inhibitors in inducing cell death; the pan-FGFR inhibitor erdafitinib displayed superior potency than FGFR4-selective inhibitors in suppressing the growth and survival of FGF19-positive HCC cells. Among FGF19-positive HCC cases from The Cancer Genome Atlas (TCGA), FGFR3 is prevalently coexpressed with FGFR4 and KLB, suggesting that FGFR redundancy may be a common mechanism underlying the de novo resistance to FGFR4 inhibitors. Our study provides a rationale for clinical testing of pan-FGFR inhibitors as a treatment strategy for FGF19-positive HCC.

Pemigatinib, a selective FGFR inhibitor overcomes ABCB1-mediated multidrug resistance in cancer cells.

P: -glycoprotein (P-gp/ABCB1) overexpression is one of the primary causes of multidrug resistance (MDR). Therefore, it is crucial to discover effective pharmaceuticals to combat multidrug resistance mediated by ABCB1. Pemigatinib is a selective the fibroblast growth factor receptor (FGFR) inhibitor that is used to treat a variety of solid tumors, Clinical Trials for Urothelial Carcinoma (NCT02872714) completed its research on Pemigatinib. This study aimed to determine whether Pemigatinib can reverse ABCB1-mediated multidrug resistance, as well as its mechanism of action. Pemigatinib substantially reversed ABCB1-mediated multidrug resistance, as determined by a CCK8 assay, and immunofluorescence experiments revealed that Pemigatinib had no effect on the intracellular localization of ABCB1. Pemigatinib was discovered to increase intracellular drug accumulation, thereby reversing multidrug resistance. In addition, Docking analysis revealed that Pemigatinib and ABCB1 have a high affinity for one another. This study concludes that Pemigatinib is capable of reversing the multidrug resistance mediated by ABCB1, offering ideas and references for the clinical application of Pemigatinib.

A phase 1/1b, open-label, dose-escalation study of PD-1 inhibitor, cetrelimab alone and in combination with FGFR inhibitor, erdafitinib in Japanese patients with advanced solid tumors.

Immune checkpoint inhibitors are the leading approaches in tumor immunotherapy. The aim of the study was to establish recommended phase 2 doses (RP2Ds) of intravenous cetrelimab, a checkpoint inhibitor, alone and with oral erdafitinib in Japanese patients with advanced solid tumors. This open-label, non-randomized, dose-escalation phase 1/1b study enrolled adults with advanced solid tumors who were ineligible for standard therapy. Study was conducted in two parts: phase 1a assessed cetrelimab at three dosing levels (80 mg every 2 weeks [Q2W], 240 mg Q2W, and 480 mg Q4W); phase 1b assessed cetrelimab+erdafitinib at two dosing levels (240 mg Q2W + 6 mg once daily [QD] and 240 mg Q2W + 8 mg QD). Primary endpoint was frequency and severity of dose-limiting toxicities (DLTs) of cetrelimab ± erdafitinib. In total 22 patients (phase 1a, n = 9; phase 1b, n = 13) were enrolled. Median duration of follow-up was 8.64 months in phase 1a and 2.33 months in phase 1b. In phase 1a, DLTs weren't reported while in phase 1b, 1 patient who received 240 mg cetrelimab + 6 mg erdafitinib reported Stevens-Johnson syndrome (grade 3, immune-related). Overall, 88.9% patients in phase 1a (grade ≥ 3: 44.4%) and 100.0% in phase 1b (grade ≥ 3: 53.8%) experienced ≥ 1 treatment-related adverse events (TEAEs); 33.3% in phase 1a and 38.5% in phase 1b reported serious TEAEs, of which 11.1% patients in phase 1a and 15.4% in phase 1b had TEAEs which led to treatment discontinuation. Cetrelimab alone and in combination with erdafitinib showed manageable safety in Japanese patients with advanced solid tumors. RP2Ds were determined as 480 mg cetrelimab Q4W for monotherapy, and cetrelimab 240 mg Q2W + erdafitinib 8 mg QD for combination therapy.

Erdafitinib in Asian patients with advanced solid tumors: an open-label, single-arm, phase IIa trial.

BACKGROUND: FGFR genomic aberrations occur in approximately 5-10% of human cancers. Erdafitinib has previously demonstrated efficacy and safety in FGFR-altered advanced solid tumors, such as gliomas, thoracic, gastrointestinal, gynecological, and other rare cancers. However, its efficacy and safety in Asian patients remain largely unknown. We conducted a multicenter, open-label, single-arm phase IIa study of erdafitinib to evaluate its efficacy in Asian patients with FGFR-altered advanced cholangiocarcinoma, non-small cell lung cancer (NSCLC), and esophageal cancer. METHODS: Patients with pathologically/cytologically confirmed, advanced, or refractory tumors who met molecular and study eligibility criteria received oral erdafitinib 8 mg once daily with an option for pharmacodynamically guided up-titration to 9 mg on a 28-day cycle, except for four NSCLC patients who received erdafitinib 10 mg (7 days on/7 days off) as they were recruited before the protocol amendment. The primary endpoint was investigator-assessed objective response rate per RECIST v1.1. Secondary endpoints included progression-free survival, duration of response, disease control rate, overall survival, safety, and pharmacokinetics. RESULTS: Thirty-five patients (cholangiocarcinoma: 22; NSCLC: 12; esophageal cancer: 1) were enrolled. At data cutoff (November 19, 2021), the objective response rate for patients with cholangiocarcinoma was 40.9% (95% CI, 20.7-63.6); the median progression-free survival was 5.6 months (95% CI, 3.6-12.7) and median overall survival was 40.2 months (95% CI, 12.4-not estimable). No patient with RET/FGFR-altered NSCLC achieved objective response and the disease control rate was 25.0% (95% CI, 5.5-57.2%), with three patients with stable disease. The single patient with esophageal cancer achieved partial response. All patients experienced treatment-emergent adverse events, and grade ≥ 3 treatment-emergent adverse events were reported in 22 (62.9%) patients. Hyperphosphatemia was the most frequently reported treatment-emergent adverse event (all-grade, 85.7%). CONCLUSIONS: Erdafitinib demonstrated efficacy in a population of Asian patients in selected advanced solid tumors, particularly in those with advanced FGFR-altered cholangiocarcinoma. Treatment was tolerable with no new safety signals. TRIAL REGISTRATION: This trial is registered with ClinicalTrials.gov (NCT02699606); study registration (first posted): 04/03/2016.

Targeting the RAS/MAPK pathway in children with glioma.

PURPOSE: Pediatric gliomas are the most common brain tumor in children, encompassing both low-grade glioma (pLGG) and high-grade glioma (pHGG). Alterations in the RAS/MAPK pathway are the driver event in the majority of pLGG and account for a subset of pHGG. Identification of these alterations has resulted in the transition to targeted therapy as a treatment option. RESULTS: In pLGG, multiple trials have demonstrated superior outcomes using targeted therapy compared to traditional chemotherapy regimens. This has transformed care for these patients over the past decade with targeted therapy moving into front-line treatment regimens in certain scenarios. Despite these advances, novel targeted therapy approaches continue to present unique challenges to patient care, including optimal duration of therapy, distinct toxicity profiles and the unknown potential impact on the natural history of disease. While targeted therapy has revolutionized treatment of pLGG, additional questions remain in regard to pHGG including the role of targeted therapy in combination with other treatments, such as chemotherapy/radiation, and mechanisms of resistance. These developments are promising treatment options for pediatrics gliomas, enabling a move towards precision medicine. CONCLUSION: Herein, we review the role of RAS/MAPK targeted therapy for treatment of pediatric glioma along with the current controversies and outstanding questions.

Plain language summary: an analysis of the safety of futibatinib treatment in people with different types of cancer.

WHAT IS THIS SUMMARY ABOUT?: Researchers combined information from three separate phase 1 and 2 clinical trials, including over 400 people who had one of 33 different cancer types and who all received futibatinib in their clinical trial. This type of study is called a pooled analysis. Futibatinib is taken orally (by mouth) as a tablet and works by reducing the activity of a group of proteins called fibroblast growth factor receptors (FGFRs). FGFRs drive the growth of some cancers, especially cancer cells with changes in FGFR genes that make the proteins more active. Researchers wanted to look at how common some side effects were in people treated with futibatinib, how soon the side effects happened after taking futibatinib, and how they could be managed. Researchers also wanted to provide recommendations to other health care professionals on how to manage these side effects in people with cancer. WHAT WERE THE RESULTS?: In this analysis, the researchers focused on side effects that they had seen in previously completed trials of futibatinib. Overall, futibatinib was safe and tolerable. Most people (82%) had a high phosphate level in their blood (hyperphosphatemia), 27% had nail disorders, 27% had liver side effects (changes in liver-related laboratory tests), 19% had a sore mouth (stomatitis), 13% had hand-foot syndrome (palmar-plantar erythrodysesthesia syndrome), 9% had a rash, 8% developed changes in the back of the eye (retinal disorders), and 4% of people developed cataracts. Most side effects were mild/moderate and reversible. The median time it took from starting treatment to experiencing a severe side effect ranged from 9 days (hyperphosphatemia) to 125 days (cataracts). Some side effects tended to occur early, while others developed later. Only 2% of people stopped taking futibatinib due to treatment-related side effects, and futibatinib caused no deaths. WHAT DO THE RESULTS MEAN?: The side effects from taking futibatinib were manageable and similar in people with different types of cancer. To fully understand the safety of futibatinib, researchers will need to look at what side effects are reported in people taking futibatinib over a longer time in the real-world setting (outside of clinical trials).

Futibatinib, an Irreversible FGFR1-4 Inhibitor for the Treatment of FGFR-Aberrant Tumors.

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

Novel parameter for cancer chemosensitivity to fibroblast growth factor receptor inhibitors.

Fibroblast growth factor receptor inhibitors (FGFRi) were introduced into clinical trials on several cancer types and found to be particularly efficacious on urothelial cancer and cholangiocarcinoma. Although many enrolled patients responded well in clinical trials, there were some patients who did not respond to FGFRi even though their tumors carried the genomic changes that met the enrollment criteria. As already established, fibroblast growth factor receptor (FGFR) and epidermal growth factor receptor (EGFR) share the downstream signaling pathway of MAPK activation. Accordingly, it is conceivable that targeted inhibition of FGFR alone could leave the MAPK signaling unaffected when the signaling through EGFR is relatively strong. To test this hypothesis, we calculated here the FGFR to EGFR mRNA ratio (F/E for short) of biliary tract and urothelial cancer cell lines utilized in preclinical studies. In six biliary tract cancer cell lines, two responsive lines had an F/E of 9.5 and 9.0, whereas the F/E of four nonresponsive lines was 0.1-1.8. In 22 urothelial cancer cell lines, four of the five responsive lines showed an F/E of 2.8-4.9 (median, 3.6), whereas the F/E range of 17 nonresponsive lines was 0.01-2.7 (median, 0.6) (p = 0.004). We further investigated our 47 patient-derived colorectal cancer-stem cell spheroid lines. The 18 responsive lines showed relatively high F/E (median, 16.4), whereas 29 nonresponsive lines had low F/E (median, 9.2) (p = 0.0006). These results suggest that F/E is another strong predictor of responses to FGFRi that is as useful as the current genomic criteria based solely on the FGFR genomic changes.

Ipatasertib (GDC-0068) and erdafitinib co-treatment for inducing mitochondrial apoptosis through Bim upregulation in bladder cancer cells.

Bladder cancer (BC) is a common malignancy of the urological system that still lacks effective treatment. It is frequently characterised by dysregulation of fibroblast growth factor receptor (FGFR) signalling. FGFR inhibitors have been proven as a promising treatment for BC in clinical settings. Besides the FGFR signalling, the therapeutic effects of FGFR inhibitors are often limited owing to various mechanisms, such as the activation of the Akt signalling pathway. Therefore, this study aimed to examine the synergistic effects of ipatasertib, a FGFR inhibitor, and erdafitinib, an Akt inhibitor, in BC cells. Ipatasertib and erdafitinib co-treatment synergistically inhibited cell proliferation and induced BC cell death. Mechanically, ipatasertib and erdafitinib induced the activation of Bax, an essential protein for cell death. Moreover, erdafitinib, which inhibited the Akt signalling pathway, is responsible for Bim upregulation, a condition critical to achieving the synergistic effects. Therefore, our data suggest that ipatasertib and erdafitinib co-treatment is a promising strategy for BC.

Evaluation of the pharmacokinetics of pemigatinib in patients with impaired hepatic or renal function.

AIMS: Pemigatinib, an inhibitor of the fibroblast growth factor receptor (FGFR) family of receptor tyrosine kinases, is approved for previously treated, unresectable locally advanced or metastatic cholangiocarcinoma. Pemigatinib is predominantly metabolized by CYP3A4 with minimal renal elimination. METHODS: Separate hepatic and renal impairment studies were conducted to evaluate the effect of these impairments on pemigatinib pharmacokinetics (PK). Each study was of open-label, parallel-group design, conducted in participants with normal organ function and with hepatic or renal impairment. Plasma concentrations of pemigatinib were quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS) and pemigatinib PK parameters were derived by noncompartmental analysis. Geometric mean ratios and two-sided 90% confidence intervals of Cmax , AUC0-t , and AUC0-∞ were compared by analysis of variance (ANOVA). RESULTS: Compared with healthy matched participants: Cmax and AUC0-∞ ratio (90% confidence interval) in participants with moderate hepatic impairment were 96.7% (59.4%, 157%) and 146% (100%, 212%), respectively; Cmax and AUC0-∞ ratio in participants with severe hepatic impairment were 94.2% (68.9%, 129%) and 174% (116%, 261%), respectively; Cmax and AUC0-∞ ratio in participants with severe renal impairment were 64.6% (44.1%, 94.4%) and 159% (95.4%, 264%), respectively; Cmax and AUC0-∞ ratio in participants with end-stage renal disease (ESRD) before haemodialysis (HD) were 77.5% (51.2%, 118%) and 76.8% (54.0%, 109%), respectively; Cmax and AUC0-∞ ratio in participants with ESRD after HD were 90.0% (59.3%, 137%) and 91.3% (64.1%, 130%), respectively. CONCLUSION: Pemigatinib dose should be reduced for patients with severe hepatic or renal impairment, and no dose adjustment is required for patients with moderate hepatic impairment or in ESRD patients undergoing HD.

Targeting FGFR3 alterations with adjuvant infigratinib in invasive urothelial carcinoma: the phase III PROOF 302 trial.

PROOF 302 is an ongoing randomized, double-blind, placebo-controlled, adjuvant phase III trial (NCT04197986) in approximately 218 patients from 120 centers worldwide. Eligibility criteria include post-surgical high-risk muscle-invasive upper tract urothelial cancer (85% of patients) or urothelial bladder cancer (15%), susceptible FGFR3 alterations (activating mutations, gene fusions or rearrangements), ≤120 days following radical surgery and ineligible for/or refusing cisplatin-based (neo)adjuvant chemotherapy. Patients receive either oral infigratinib 125 mg or placebo daily on days 1-21 of a 28-day cycle for up to 52 weeks or until recurrence, unacceptable toxicity or death. Primary end point: centrally determined disease-free survival (DFS); secondary end points: investigator-assessed DFS, metastasis-free survival, overall survival and safety/tolerability; exploratory end points: correlative biomarker analysis, quality-of-life and infigratinib pharmacokinetics.

Cancers of the bladder and other parts in the urinary system, especially those that are invasive and grow into the muscle layer, may need extra treatment after surgical removal of the tumor, particularly if there is a high risk of the cancer coming back. Chemotherapy regimens that include cisplatin are often used postoperatively, although some patients are unable to tolerate this treatment or refuse it. FGFR3, a protein that is encoded by the FGFR3 gene, is often changed in these cancers. This helps the tumor grow. Infigratinib is an investigational drug that targets FGFR3 and inhibits the abnormal growth of the tumor. In the PROOF 302 study, patients are randomly assigned to treatment with infigratinib or a placebo pill for 1 year after surgery to see if the drug is effective. The aim is to see if patients who take infigratinib have a longer time free from the disease than those who receive a placebo. The study will also look at how long patients remain free from cancer spread and how long they live overall. The study will also investigate how safe the treatment is and how easy it is to live with it. PROOF 302 is an important study as it will define the role of infigratinib in patients with cancers of the bladder and urinary system who also have FGFR3 changes, for whom more treatment choices are needed. Clinical Trial Registration: NCT04197986 (ClinicalTrials.gov).

FGFR1-4 RNA-Based Gene Alteration and Expression Analysis in Squamous Non-Small Cell Lung Cancer.

While fibroblast growth factor receptors (FGFRs) are involved in several biological pathways and FGFR inhibitors may be useful in the treatment of squamous non-small cell lung cancer (Sq-NSCLC), FGFR aberrations are not well characterized in Sq-NSCLC. We comprehensively evaluated FGFR expression, fusions, and variants in 40 fresh-frozen primary Sq-NSCLC (stage IA3−IV) samples and tumor-adjacent normal tissues using real-time PCR and next-generation sequencing (NGS). Protein expression of FGFR1−3 and amplification of FGFR1 were also analyzed. FGFR1 and FGFR4 median gene expression was significantly (p < 0.001) decreased in tumors compared with normal tissue. Increased FGFR3 expression enhanced the recurrence risk (hazard ratio 4.72, p = 0.029), while high FGFR4 expression was associated with lymph node metastasis (p = 0.036). Enhanced FGFR1 gene expression was correlated with FGFR1 protein overexpression (r = 0.75, p = 0.0003), but not with FGFR1 amplification. NGS revealed known pathogenic FGFR2,3 variants, an FGFR3::TACC3 fusion, and a novel TACC1::FGFR1 fusion together with FGFR1,2 variants of uncertain significance not previously reported in Sq-NSCLC. These findings expand our knowledge of the Sq-NSCLC molecular background and show that combining different methods increases the rate of FGFR aberrations detection, which may improve patient selection for FGFRi treatment.

Ribociclib enhances infigratinib-induced cancer cell differentiation and delays resistance in FGFR-driven hepatocellular carcinoma.

BACKGROUND & AIMS: Infigratinib is a pan-FGFR (fibroblast growth factor receptor) inhibitor that has shown encouraging activity in FGFR-dependent hepatocellular carcinoma (HCC) models. However, long-term treatment results in the emergence of resistant colonies. We sought to understand the mechanisms behind infigratinib-induced tumour cell differentiation and resistance and to explore the potential of adding the CDK4/6 inhibitor ribociclib to prolong cell differentiation. METHODS: Nine high and three low FGFR1-3-expressing HCC patient-derived xenograft (PDX) tumours were subcutaneously implanted into SCID mice and subsequently treated with either infigratinib alone or in combination with ribociclib. Tumour tissues were then subjected to immunohistochemistry to assess cell differentiation, as indicated by the cytoplasmic-to-nuclear ratio and markers such as CYP3A4, HNF4α and albumin. Western blot analyses were performed to investigate the signalling pathways involved. RESULTS: Infigratinib induced cell differentiation in FGFR1-3-dependent HCC PDX models, as indicated by an increase in the cytoplasmic/nuclear ratio and an increase in CYP3A4, HNF4α and albumin. Resistant colonies emerged in long-term treatment, characterised by a reversal of differentiated cell morphology, a reduction in the cytoplasmic-to-nuclear ratio and a loss of differentiation markers. Western blot analyses identified an increase in the CDK4/Cdc2/Rb pathway. The addition of ribociclib effectively blocked this pathway and reversed resistance to infigratinib, resulting in prolonged cell differentiation and growth inhibition. CONCLUSIONS: Our findings demonstrate that the combined inhibition of FGFR/CDK4/6 pathways is highly effective in providing long-lasting tumour growth inhibition and cell differentiation and reducing drug resistance. Therefore, further clinical investigations in patients with FGFR1-3-dependant HCC are warranted.

Evaluation of drug-drug interactions of pemigatinib in healthy participants.

PURPOSE: Pemigatinib (INCB054828), a potent and selective oral fibroblast growth factor receptor 1-3 inhibitor, is a Biopharmaceutical Classification System class II compound with good permeability and pH-dependent solubility that is predominantly metabolized by cytochrome P450 (CYP) 3A. Two drug-drug interaction studies, one with acid-reducing agents, esomeprazole (proton pump inhibitor [PPI]) and ranitidine (histamine-2 [H2] antagonist), and the other with potent CYP3A-modulating agents, itraconazole (CYP3A inhibitor) and rifampin (CYP3A inducer), were performed. METHODS: Both were open-label, fixed-sequence studies conducted in up to 36 healthy participants each, enrolled into two cohorts (n = 18 each). Pemigatinib plasma concentration was measured, and pharmacokinetic parameters were derived by non-compartmental analysis. RESULTS: There was an 88% and 17% increase in pemigatinib area under the plasma drug concentration-time curve (AUC) and maximum plasma drug concentration (Cmax), respectively, with itraconazole, and an 85% and 62% decrease in pemigatinib AUC and Cmax with rifampin coadministration. There was a 35% and 8% decrease in pemigatinib AUC and Cmax, respectively, with esomeprazole, and a 2% decrease in Cmax and 3% increase in AUC with ranitidine coadministration. In both studies, all adverse events reported were grade ≤ 2. CONCLUSION: Coadministration with itraconazole or rifampin resulted in a clinically significant change in pemigatinib exposure. Therefore, coadministration of strong CYP3A inducers with pemigatinib should be avoided, and the dose of pemigatinib should be reduced if coadministration with strong CYP3A inhibitors cannot be avoided. The effect of PPIs/H2 antagonists on pemigatinib exposure was modest, and pemigatinib can be administered without regard to coadministration of PPIs/H2 antagonists.

Pemigatinib, a potent inhibitor of FGFRs for the treatment of cholangiocarcinoma.

The prognosis of patients affected by cholangiocarcinoma is classically poor. Until recently, chemotherapeutic drugs were the only systemic treatment option available, leading to an overall survival lower than 1 year. In recent decades, different genetic alterations have been identified as playing a key role in the oncogenic signaling. A subgroup of intrahepatic cholangiocarcinoma is characterized by FGFR family mutations, more frequently represented by gene fusions of FGFR2. Based on the results of FIGHT-202 trial, in April 2020 the US FDA approved the FGFR inhibitor pemigatinib in advanced previously treated cholangiocarcinoma patients with FGFR2 rearrangements, opening the way to targeted therapy in this disease. This review summarizes the body of evidence about the efficacy of pemigatinib in cholangiocarcinoma.

DW14383 is an irreversible pan-FGFR inhibitor that suppresses FGFR-dependent tumor growth in vitro and in vivo.

Fibroblast growth factor receptor (FGFR) is a promising anticancer target. Currently, most FGFR inhibitors lack sufficient selectivity and have nonnegligible activity against kinase insert domain receptor (KDR), limiting their feasibility due to the serious side effects. Notably, compensatory activation occurs among FGFR1-4, suggesting the urgent need to develop selective pan-FGFR1-4 inhibitors. Here, we explored the antitumor activity of DW14383, a novel irreversible FGFR1-4 inhibitor. DW14383 exhibited equivalently high potent inhibition against FGFR1, 2, 3 and 4, with IC50 values of less than 0.3, 1.1, less than 0.3, and 0.5 nmol/L, respectively. It is a selective FGFR inhibitor, exhibiting more than 1100-fold selectivity for FGFR1 over recombinant KDR, making it one of the most selective FGFR inhibitors over KDR described to date. Furthermore, DW14383 significantly inhibited cellular FGFR1-4 signaling, inducing G1/S cell cycle arrest, which in turn antagonized FGFR-dependent tumor cell proliferation. In contrast, DW14383 had no obvious antiproliferative effect against cancer cell lines without FGFR aberration, further confirming its selectivity against FGFR. In representative FGFR-dependent xenograft models, DW14383 oral administration substantially suppressed tumor growth by simultaneously inhibiting tumor proliferation and angiogenesis via inhibiting FGFR signaling. In summary, DW14383 is a promising selective irreversible pan-FGFR inhibitor with pan-tumor spectrum potential in FGFR1-4 aberrant cancers, which has the potential to overcome compensatory activation among FGFR1-4.

Metabolism and disposition in rats, dogs, and humans of erdafitinib, an orally administered potent pan-fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor.

This article describes in vivo biotransformation and disposition of erdafitinib following single oral dose of 3H-erdafitinib and 14C-erdafitinib to intact and bile duct-cannulated (BC) rats (4 mg/kg), 3H-erdafitinib to intact dogs (0.25 mg/kg), and 14C-erdafitinib to humans (12 mg; NCT02692677). Peak plasma concentrations of total radioactivity were achieved rapidly (Tmax: animals, 1 h; humans, 2-3 h). Recovery of drug-derived radioactivity was significantly slower in humans (87%, 384 h) versus animals (rats: 91-98%, 48 h; dogs: 81%, 72 h). Faeces was the primary route of elimination in intact rats (95%), dogs (76%), and humans (69%); and bile in BC rats (48%). Renal elimination of radioactivity was relatively low in animals (2-12%) versus humans (19%). Unchanged erdafitinib was major component in human excreta (faeces, 17%; urine, 11%) relative to animals. M6 (O-desmethyl) was the major faecal metabolite in humans (24%) and rats (intact, 46%; BC, 11%), and M2 (O-glucuronide of M6) was the prevalent biliary metabolite in rats (14%). In dogs, besides M6, majority of radioactive dose in faeces was composed of multiple minor metabolites. In humans, unchanged erdafitinib was the major circulating entity. O-demethylation of erdafitinib was the major metabolic pathway in humans and animals.

Increased interdigitation zone visibility on optical coherence tomography following systemic fibroblast growth factor receptor 1-3 tyrosine kinase inhibitor anticancer therapy.

BACKGROUND: To describe ocular adverse events and retinal changes during fibroblast growth factor receptor (FGFR) inhibitor (AZD4547) anticancer therapy. METHODS: This is a sub-study examining ocular adverse effects from AZD4547 therapy (single-centre, open-label, single arm phase II clinical trial). Comprehensive ocular examinations were performed 3 weekly in 24 patients. Macular optical coherence tomography (OCT) scan (300 × 250 ) was obtained at each visit and OCT parameters [central 1 mm retinal thickness (CRT) and total macular volume in central 6 mm] extracted. OCT scans were subdivided into outer (ELM to RPE) and inner (ELM to ILM) layers to compare outer and inner retinal changes. RESULTS: In 24 patients, AZD4547 was associated with eyelash elongation (n = 5, 21%) and punctate corneal erosion (n = 2, 8%). One patient developed clinically significant posterior capsular opacification during the study. OCT data were available in 23 patients, retinal changes ranged from an asymptomatic increased visibility of the interdigitation zone (IDZ) (n = 10, 43%) to multilobular subretinal fluid pockets (n = 5, 22%), which was associated with mild visual acuity loss. In a subset of patients (n = 9) with pre-AZD4547 dosing OCT baseline, CRT increased by mean (SD) of 9 (4) µm in those with IDZ change only compared with 64 (38) µm in those with other retinal changes. Retinal changes tended to be bilateral, self-limiting and improved over time without medical intervention. CONCLUSIONS: The ocular signs and symptoms did not result in dose cessation. Posteriorly, FGFR inhibition leads to outer retinal changes ranging from increased visibility of IDZ to distinct, multiple fluid pockets.

Phase I, first-in-human study of futibatinib, a highly selective, irreversible FGFR1-4 inhibitor in patients with advanced solid tumors.

BACKGROUND: Futibatinib is an oral, irreversible, highly selective fibroblast growth factor receptor (FGFR)1-4 inhibitor with potent preclinical activity against tumors harboring FGFR aberrations. This first-in-human, phase I dose-escalation trial (NCT02052778) evaluates the safety and pharmacokinetics/pharmacodynamics of futibatinib in advanced solid tumors. PATIENTS AND METHODS: Following a standard 3+3 dose-escalation design, eligible patients with advanced solid tumors refractory to standard therapies received 8-200 mg futibatinib three times a week (t.i.w.) or 4-24 mg once daily (q.d.). RESULTS: A total of 86 patients were enrolled in the nine t.i.w. (n = 42) and five q.d. cohorts (n = 44); 71 patients (83%) had tumors harboring FGF/FGFR aberrations. Three of nine patients in the 24-mg q.d. cohort experienced dose-limiting toxicities, including grade 3 increases in alanine transaminase, aspartate transaminase, and blood bilirubin (n = 1 each). The maximum tolerated dose (MTD) was determined to be 20 mg q.d.; no MTD was defined for the t.i.w. schedule. Across cohorts (n = 86), the most common treatment-emergent adverse events (TEAEs) were hyperphosphatemia (59%), diarrhea (37%), and constipation (34%); 48% experienced grade 3 TEAEs. TEAEs led to dose interruptions, dose reductions, and treatment discontinuations in 55%, 14%, and 3% of patients, respectively. Pharmacokinetics were dose proportional across all q.d. doses but not all t.i.w. doses evaluated, with saturation observed between 80 and 200 mg t.i.w. Serum phosphorus increased dose dependently with futibatinib on both schedules, but a stronger exposure-response relationship was observed with q.d. dosing, supporting 20 mg q.d. as the recommended phase II dose (RP2D). Overall, partial responses were observed in five patients [FGFR2 fusion-positive intrahepatic cholangiocarcinoma (n = 3) and FGFR1-mutant primary brain tumor (n = 2)], and stable disease in 41 (48%). CONCLUSIONS: Futibatinib treatment resulted in manageable safety, pharmacodynamic activity, and preliminary responses in patients with advanced solid tumors. The results of this phase I dose-escalation trial support 20 mg q.d. futibatinib as the RP2D. CLINICAL TRIAL REGISTRATION: FOENIX-101 (ClinicalTrials.gov, NCT02052778).

Sequencing Endocrine Therapy for Metastatic Breast Cancer: What Do We Do After Disease Progression on a CDK4/6 Inhibitor?

PURPOSE OF REVIEW: Cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors have revolutionized the treatment landscape for patients with hormone receptor-positive (HR+) and HER2-negative (HER2-) metastatic breast cancer (MBC). However, optimal therapy after CDK4/6 inhibitors is unknown. This review provides an update on recent understanding of potential resistance mechanisms to CDK4/6 inhibitors and therapeutic strategies. RECENT FINDINGS: CDK4/6 inhibitors are broadly effective for HR+/HER2- MBC. However, intrinsic and acquired resistance is inevitable. Although there are no established clinical predictors of response aside from ER positivity, several cell cycle-specific and non-specific mechanisms have emerged as potential resistance biomarkers and therapeutic targets in recent studies. Examples include loss of function mutations in RB1 or FAT1, overexpression or amplification of CDK6 and CCNE1, alterations of FGFR, and PI3K/mTOR-mediated CDK2 activation. Biomarker studies and clinical trials targeting CDK4/6 inhibitor resistance are critical to improve treatments for HR+/HER2- MBC.