Pharmacology: Mechanism of Action: Erdafitinib is a kinase inhibitor that binds to and inhibits enzymatic activity of FGFR1, FGFR2, FGFR3 and FGFR4 based on
in vitro data. Erdafitinib inhibited FGFR phosphorylation and signaling and decreased cell viability in cell lines expressing FGFR genetic alterations, including point mutations, amplifications, and fusions. Erdafitinib demonstrated antitumor activity in FGFR-expressing cell lines and xenograft models derived from tumor types, including bladder cancer.
Pharmacodynamics: Cardiac Electrophysiology: Based on evaluation of QTc interval in an open-label, dose escalation and dose expansion study in 187 patients with cancer, erdafitinib had no large effect (i.e., >20 ms) on the QTc interval.
Serum Phosphate: FGFR inhibition by BALVERSA increases serum phosphate level [see Dose Modifications for Adverse Reactions under Dosage & Administration and Interactions].
Clinical Studies: Urothelial Carcinoma with Susceptible FGFR3 Genetic Alterations: The efficacy of BALVERSA was evaluated in Study BLC3001 (NCT03390504) Cohort 1, a randomized, open-label, multicenter study in which 266 patients with advanced urothelial cancer harboring selected FGFR3 alterations were randomized 1:1 to receive BALVERSA (8 mg with titration up to 9 mg) versus chemotherapy (docetaxel 75 mg/m
2 once every 3 weeks or vinflunine 320 mg/m
2 once every 3 weeks) until unacceptable toxicity or progression. Randomization was stratified by region (North America vs. Europe vs. rest of world), Eastern Cooperative Oncology Group (ECOG) performance status (0 or 1 vs. 2) and visceral or bone metastases (yes vs. no). All patients needed to have had disease progression after 1 or 2 prior treatments, at least 1 of which included a PD-1 or PD-L1 inhibitor. FGFR3 genetic alterations were identified from tumor tissue in a central laboratory by the QIAGEN
therascreen FGFR RGQ RT-Polymerase Chain Reaction (PCR) kit in 75% of patients while the remainder (25%) were identified by local next generation sequencing (NGS) assays.
The major efficacy outcome measures were overall survival (OS), progression-free survival (PFS), and objective response rate (ORR) assessed by investigator using RECIST (Response Evaluation Criteria in Solid Tumors) Version 1.1.
The median age was 67 years (range: 32 to 86 years) and 71% were male; 54% were White, 29% Asian, 0.4% Black, 0.4% multiple races, 16% not reported; 2% were Hispanic/Latino; and baseline ECOG performance status was 0 (43%), 1 (48%), or 2 (9%). Eighty-one percent of patients had FGFR3 mutations, 17% had fusions, and 2% had both mutations and fusions. Ninety-five percent of patients had pure transitional cell carcinoma (TCC) and 5% had TCC with other histologic variants. The primary tumor location was the upper tract for 33% of subjects and lower tract for 67%; 74% of patients had visceral or bone metastases. Eighty-eight percent of patients received platinum-containing chemotherapy previously. PD-1 or PD-L1 inhibitor therapy was received only in the neoadjuvant or adjuvant setting in 7% of patients.
Statistically significant improvements in OS, PFS, and ORR were demonstrated for BALVERSA compared with chemotherapy.
Table 1 and Figures 1 and 2 summarize the efficacy results for BLC3001 Cohort 1. (See Table 1, Figures 1 and 2.)
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Study BLC3001 Cohort 2: Study BLC3001 (NCT03390504) Cohort 2 was a multicenter, open-label, randomized study in 351 patients with locally advanced or metastatic urothelial carcinoma with selected FGFR3 alterations who received 1 prior line of systemic therapy and no prior PD-1 or PD-L1 inhibitor. Patients were randomized 1:1 to receive BALVERSA (8 mg with titration up to 9 mg) or pembrolizumab 200 mg every 3 weeks. The study did not meet its major efficacy outcome measure for superiority of OS at the pre-specified final analysis. The OS hazard ratio (HR) was 1.18 (95% CI: 0.92, 1.51; p=0.18), median 10.9 (95% CI: 9.2, 12.6) months for BALVERSA versus 11.1 (95% CI: 9.7, 13.6) months for pembrolizumab [see Indications/Uses].
Study BLC2001: Study BLC2001 (NCT02365597) was a multicenter, open-label, single-arm study to evaluate the efficacy and safety of BALVERSA in patients with locally advanced or metastatic urothelial carcinoma (mUC). FGFR mutation status for screening and enrollment of patients was determined by a clinical trial assay (CTA). The efficacy population consists of a cohort of eighty-seven patients who were enrolled in this study with disease that had progressed on or after at least one prior chemotherapy and that had at least 1 of the following genetic alterations: FGFR3 gene mutations (R248C, S249C, G370C, Y373C) or FGFR gene fusions (FGFR3-TACC3, FGFR3-BAIAP2L1, FGFR2BICC1, FGFR2-CASP7), as determined by the CTA performed at a central laboratory. Tumor samples from 69 patients were tested retrospectively by the QIAGEN
therascreen FGFR RGQ RT-PCR Kit, which is the validated test for selection of patients with mUC for BALVERSA.
Patients received a starting dose of BALVERSA at 8 mg once daily with a dose increase to 9 mg once daily in patients whose serum phosphate levels were below the target of 5.5 mg/dL between days 14 and 17; a dose increase occurred in 41% of patients. BALVERSA was administered until disease progression or unacceptable toxicity. The major efficacy outcome measures were ORR and duration of response (DoR), as determined by blinded independent review committee (BIRC) according to RECIST v1.1.
The median age was 67 years (range: 36 to 87 years), 79% were male, and 74% were Caucasian. Most patients (92%) had a baseline Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. Sixty-six percent of patients had visceral metastases. Eighty-four (97%) patients received at least one of cisplatin or carboplatin previously. Fifty-six percent of patients only received prior cisplatin-based regimens, 29% received only prior carboplatin-based regimens, and 10% received both cisplatin and carboplatin-based regimens. Three (3%) patients had disease progression following prior platinum-containing neoadjuvant or adjuvant therapy only. Twenty-four percent of patients had been treated with prior anti PD-L1/PD-1 therapy.
Efficacy results are summarized in Table 2 and Table 3. ORR was 32.2%. Responders included patients who had previously not responded to anti PD-L1/PD-1 therapy. (See Tables 2 and 3.)
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Pharmacokinetics: Following administration of BALVERSA 8 mg once daily, the mean (coefficient of variation [CV%]) erdafitinib steady-state maximum plasma concentration (C
max), area under the curve (AUC
tau), and minimum plasma concentration (C
min) were 1,399 ng/mL (51%), 29,268 ng·h/mL (60%), and 936 ng/mL (65%), respectively.
Following single and repeat once daily dosing of BALVERSA, erdafitinib exposure (C
max and AUC) increased proportionally across the dose range of 0.5 to 12 mg (0.06 to 1.3 times the maximum approved recommended dose). Steady state was achieved after 2 weeks with once daily dosing with a mean accumulation ratio was 4-fold.
Absorption: Median time to achieve peak plasma concentration (t
max) was 2.5 hours (range: 2 to 6 hours).
Effect of Food: No clinically meaningful differences in erdafitinib exposure was observed following administration of BALVERSA with a high-fat and high-calorie meal (800 calories to 1,000 calories with approximately 50% of total caloric content of the meal from fat).
Distribution: The mean apparent volume of distribution of erdafitinib was 29 L.
Erdafitinib protein binding was 99.7% in patients, primarily to alpha-1-acid glycoprotein.
Elimination: The mean total apparent clearance (CL/F) of erdafitinib was 0.362 L/h.
The mean effective half-life of erdafitinib was 59 hours.
Metabolism: Erdafitinib is primarily metabolized by CYP2C9 and CYP3A4. The contribution of CYP2C9 and CYP3A4 in the total clearance of erdafitinib is estimated to be 39% and 20%, respectively. Unchanged erdafitinib was the major drug-related moiety in plasma, there were no circulating metabolites.
Excretion: Following a single oral dose of radiolabeled erdafitinib, approximately 69% of the dose was recovered in feces (19% as unchanged) and 19% in urine (13% as unchanged).
Specific Populations: No clinically meaningful effects on erdafitinib exposure were observed based on age (21-92 years), sex, race (White, Hispanic or Asian), body weight (36-166 kg), mild (Child-Pugh A) or moderate (Child-Pugh B) hepatic impairment, or mild to moderate renal impairment (eGFR 30 to 89 mL/min/1.73 m²). Limited data are available in patients with severe (Child-Pugh C) hepatic impairment and in patients with severe renal impairment. The pharmacokinetics of erdafitinib in patients with renal impairment requiring dialysis is unknown.
Drug Interaction Studies: Clinical Studies: Effect of Other Drugs on Erdafitinib: Moderate CYP2C9 Inhibitors: Erdafitinib mean ratios for C
max and AUC
inf were 121% and 148%, respectively, when BALVERSA was co-administered with fluconazole, a moderate CYP2C9 and CYP3A4 inhibitor, relative to BALVERSA administered alone.
Strong CYP3A4 Inhibitors: Erdafitinib mean ratios for C
max and AUC
inf were 105% and 134%, respectively, when BALVERSA was co-administered with itraconazole (a strong CYP3A4 inhibitor and P-gp inhibitor) relative to BALVERSA alone.
CYP3A4/2C9 Inducers: Erdafitinib mean ratios for C
max and AUC
inf were 78% and 45%, respectively, when BALVERSA was co-administered with carbamazepine (a strong CYP3A4 and weak CYP2C9 inducer) relative to BALVERSA alone.
Effect of Erdafitinib on Other Drugs: CYP3A4 Substrates: No clinically meaningful effect on the exposure of midazolam (a CYP3A4 substrate) was observed following coadministration with BALVERSA.
OCT2 Substrates: No clinically meaningful effect on the exposure of metformin (an OCT2 substrate) was observed following coadministration with BALVERSA.
In Vitro Studies: CYP Substrates: Erdafitinib is a time dependent inhibitor and inducer of CYP3A4. Erdafitinib is not an inhibitor of other major CYP isozymes at clinically relevant concentrations.
Transporters: Erdafitinib is a substrate and inhibitor of P-gp. P-gp inhibitors are not expected to affect erdafitinib exposure to a clinically relevant extent. Erdafitinib is an inhibitor of OCT2.
Erdafitinib does not inhibit BCRP, OATP1B, OATP1B3, OAT1, OAT3, OCT1, MATE-1, or MATE-2K at clinically relevant concentrations.
Acid-Lowering Agents: Erdafitinib has adequate solubility across the pH range of 1 to 7.4. Acid-lowering agents (including antacids, H
2-antagonists and proton pump inhibitors) are not expected to affect the bioavailability of erdafitinib.
Pharmacogenomics: CYP2C9 activity is reduced in individuals with genetic variants, such as the CYP2C9*2 and CYP2C9*3 polymorphisms. Erdafitinib exposure was similar in subjects with CYP2C9*1/*2 and *1/*3 genotypes relative to subjects with CYP2C9*1/*1 genotype (wild type). No data are available in subjects characterized by other genotypes (e.g., *2/*2, *2/*3, *3/*3). Simulation suggested no clinically meaningful differences in erdafitinib exposure in subjects with CYP2C9*2/*2 and *2/*3 genotypes. The exposure of erdafitinib is predicted to be 50% higher in subjects with the CYP2C9*3/*3 genotype, estimated to be present in 0.4% to 3% of the population among various ethnic groups.
Toxicology: Preclinical Safety data: Carcinogenesis, Mutagenesis, and Impairment of Fertility: Carcinogenicity studies have not been conducted with erdafitinib.
Erdafitinib was not mutagenic in a bacterial reverse mutation (Ames) assay and was not clastogenic in an
in vitro micronucleus or an
in vivo rat bone marrow micronucleus assay.
Fertility studies in animals have not been conducted with erdafitinib. In the 3-month repeat-dose toxicity study, erdafitinib showed effects on female reproductive organs (necrosis of the ovarian corpora lutea) in rats at an exposure less than the human exposure (AUC) at maximum recommended human dose.