ERDAFITINIB Drug Interactions: What You Need to Know

INTERACTIONS Moderate CYP2C9 or strong CYP3A4 inhibitors: Consider alternative agents or monitor closely for adverse reactions. ( 7.1 ) Strong CYP3A4 inducers: Avoid concomitant use with BALVERSA. ( 7.1 ) Moderate CYP3A4 inducers: Administer BALVERSA at a dose of 9 mg. ( 7.1 ) Serum phosphate level-altering agents: Avoid concomitant use with agents that can alter serum phosphate levels before the initial dose modification period. ( 2.3 , 7.1 ) P-gp substrates: Separate BALVERSA administration by at least 6 hours before or after administration of P-gp substrates with narrow therapeutic indices. ( 7.2 )

7.1 Effect of Other Drugs on BALVERSA Table 7 summarizes drug interactions that affect the exposure of BALVERSA or serum phosphate level and their clinical management.

Table

7: Drug Interactions that Affect BALVERSA Moderate CYP2C9 or Strong CYP3A4 Inhibitors Clinical Impact Co-administration of BALVERSA with moderate CYP2C9 or strong CYP3A4 inhibitors increased erdafitinib plasma concentrations [see Clinical Pharmacology (12.3) ]. Increased erdafitinib plasma concentrations may lead to increased drug-related toxicity [see Warnings and Precautions (5) ].

Clinical Management

Consider alternative therapies that are not moderate CYP2C9 or strong CYP3A4 inhibitors during treatment with BALVERSA. If co-administration of a moderate CYP2C9 or strong CYP3A4 inhibitor is unavoidable, monitor closely for adverse reactions and consider dose modifications accordingly [see Dosage and Administration (2.3) ]. If the moderate CYP2C9 or strong CYP3A4 inhibitor is discontinued, resume the BALVERSA dose before dose modifications in the absence of drug-related toxicity. Strong CYP3A4 Inducers Clinical Impact Co-administration of BALVERSA with strong CYP3A4 inducers decreased erdafitinib plasma concentrations [see Clinical Pharmacology (12.3) ]. Decreased erdafitinib plasma concentrations may lead to decreased activity.

Clinical Management

Avoid co-administration of strong CYP3A4 inducers with BALVERSA. Moderate CYP3A4 Inducers Clinical Impact Co-administration of BALVERSA with moderate CYP3A4 inducers may decrease erdafitinib plasma concentrations [see Clinical Pharmacology (12.3) ]. Decreased erdafitinib plasma concentrations may lead to decreased activity.

Clinical

Management If a moderate CYP3A4 inducer must be co-administered at the start of BALVERSA treatment, administer BALVERSA at a dose of 9 mg daily. When a moderate CYP3A4 inducer is discontinued, continue BALVERSA at the same dose, in the absence of drug-related toxicity.

Serum Phosphate

Level-Altering Agents Clinical Impact Co-administration of BALVERSA with other serum phosphate level-altering agents may increase or decrease serum phosphate levels [see Pharmacodynamics (12.2) ]. Changes in serum phosphate levels due to serum phosphate level-altering agents (other than erdafitinib) may interfere with serum phosphate levels needed for the determination of initial dose increased based on serum phosphate levels [see Dosage and Administration (2.3) ].

Clinical Management

Avoid co-administration of serum phosphate level-altering agents with BALVERSA before initial dose increase period based on serum phosphate levels (Days 14 to 21) [see Dosage and Administration (2.3) ].

7.2 Effect of BALVERSA on Other Drugs Table 8 summarizes the effect of BALVERSA on other drugs and their clinical management.

Table

8: BALVERSA Drug Interactions that Affect Other Drugs P-glycoprotein (P-gp)

Substrates Clinical

Impact Co-administration of BALVERSA with P-gp substrates may increase the plasma concentrations of P-gp substrates [see Clinical Pharmacology (12.3) ]. Increased plasma concentrations of P-gp substrates may lead to increased toxicity of the P-gp substrates.

Clinical

Management If co-administration of BALVERSA with P-gp substrates is unavoidable, separate BALVERSA administration by at least 6 hours before or after administration of P-gp substrates with narrow therapeutic index.

None. None. ( 4 )

AND PRECAUTIONS Ocular disorders: BALVERSA can cause central serous retinopathy/retinal pigment epithelial detachment (CSR/RPED). Perform monthly ophthalmological examinations during the first four months of treatment, every 3 months afterwards, and at any time for visual symptoms. Withhold BALVERSA when CSR/RPED occurs and permanently discontinue if it does not resolve within 4 weeks or if Grade 4 in severity. ( 2.3 , 5.1 ) Hyperphosphatemia: Increases in phosphate levels are a pharmacodynamic effect of BALVERSA. Monitor for hyperphosphatemia and manage with dose modifications when required. ( 2.3 , 5.2 ) Embryo-fetal toxicity: Can cause fetal harm. Advise patients of the potential risk to the fetus and to use effective contraception ( 5.3 , 8.1 , 8.3)

5.1 Ocular Disorders BALVERSA can cause ocular disorders, including central serous retinopathy/retinal pigment epithelial detachment (CSR/RPED) resulting in visual field defect. In the pooled safety population <span class="opacity-50 text-xs">[see Adverse Reactions (6) ]</span> , CSR/RPED occurred in 22% of patients treated with BALVERSA, with a median time to first onset of 46 days.

In

104 patients with CSR, 40% required dose interruptions and 56% required dose reductions; 2.9% of BALVERSA-treated patients required permanent discontinuation for CSR. Of the 24 patients who restarted BALVERSA after dose interruption with or without dose reduction, 67% had recurrence and/or worsening of CSR after restarting. CSR was ongoing in 41% of the 104 patients at the time of last evaluation. Dry eye symptoms occurred in 26% of BALVERSA-treated patients. All patients should receive dry eye prophylaxis with ocular demulcents as needed. Perform monthly ophthalmological examinations during the first 4 months of treatment and every 3 months afterwards, and urgently at any time for visual symptoms. Ophthalmological examination should include assessment of visual acuity, slit lamp examination, fundoscopy, and optical coherence tomography. Withhold or permanently discontinue BALVERSA based on severity and/or ophthalmology exam findings [see Dosage and Administration (2.3) ] .

5.2 Hyperphosphatemia and Soft Tissue Mineralization BALVERSA can cause hyperphosphatemia leading to soft tissue mineralization, cutaneous calcinosis, non-uremic calciphylaxis and vascular calcification. Increases in phosphate levels are a pharmacodynamic effect of BALVERSA <span class="opacity-50 text-xs">[see Pharmacodynamics (12.2) ]</span>. In the pooled safety population <span class="opacity-50 text-xs">[see Adverse Reactions (6) ]</span>, increased phosphate occurred in 73% of BALVERSA-treated patients. The median onset time of increased phosphate was 16 days (range: 8–421) after initiating BALVERSA. Twenty-four percent of patients received phosphate binders during treatment with BALVERSA. Vascular calcification was observed in 0.2% of patients treated with BALVERSA. Monitor for hyperphosphatemia throughout treatment. Restrict dietary phosphate intake (600–800 mg daily) and avoid concomitant use of agents that may increase serum phosphate levels. If serum phosphate is above 7.0 mg/dL, consider adding an oral phosphate binder until serum phosphate level returns to &lt;7.0 mg/dL. Withhold, dose reduce, or permanently discontinue BALVERSA based on duration and severity of hyperphosphatemia according to Table 2 <span class="opacity-50 text-xs">[see Dosage and Administration (2.3) ]</span>.

5.3 Embryo-Fetal Toxicity Based on the mechanism of action and findings in animal reproduction studies, BALVERSA can cause fetal harm when administered to a pregnant woman. In an embryo-fetal toxicity study, oral administration of erdafitinib to pregnant rats during the period of organogenesis caused malformations and embryo-fetal death at maternal exposures that were less than the human exposures at the maximum human recommended dose based on area under the curve (AUC). Advise pregnant women of the potential risk to the fetus. Advise female patients of reproductive potential to use effective contraception during treatment with BALVERSA and for one month after the last dose. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with BALVERSA and for one month after the last dose <span class="opacity-50 text-xs">[see Use in Specific Populations (8.1 , 8.3) and Clinical Pharmacology (12.1) ]</span> .