warnings and cautions
5 WARNINGS AND PRECAUTIONS Hepatotoxicity: Monitor liver function tests prior to initiating, every 2 weeks during the first 2 months of treatment, then monthly thereafter as clinically indicated, with more frequent testing in patients who develop transaminase elevations. Based on severity and resolution, withhold and then resume at reduced dose, or permanently discontinue. ( 2.4 , 5.1 ) Interstitial Lung Disease (ILD)/Pneumonitis: Monitor patients for new or worsening pulmonary symptoms indicative of ILD/pneumonitis. Immediately withhold in patients with suspected ILD/pneumonitis. Based on severity and resolution, resume at the same or reduced dose, or permanently discontinue. ( 2.4 , 5.2 ) QTc Interval Prolongation: Monitor ECG and electrolytes prior to initiating and periodically during treatment. Based on severity and resolution, withhold and then resume at same or reduced dose, or permanently discontinue. ( 2.4 , 5.3 ) Hyperuricemia: Monitor serum uric acid levels prior to initiating and periodically during treatment. Initiate treatment with urate-lowering medications as clinically indicated. Withhold and resume at same or reduced dose or permanently discontinue based on severity. ( 2.4 , 5.4 ) Myalgia with Creatine Phosphokinase (CPK) Elevation: Monitor serum CPK levels during treatment in patients reporting unexplained muscle pain, tenderness, or weakness. Based on severity, withhold and resume at same or reduced dose upon improvement. ( 2.4 , 5.5 ) Skeletal Fractures: Promptly evaluate patients with signs or symptoms (e.g., pain, changes in mobility, deformity) of fractures. ( 5.6 ) Embryo-Fetal Toxicity: Can cause fetal harm. Advise patients of the potential risk to a fetus and to use effective contraception. ( 5.7 ) 5.1 Hepatotoxicity IBTROZI can cause hepatotoxicity, including drug-induced liver injury and fatal adverse reactions. In the pooled safety population [see Adverse Reactions ( 6.1 )], based on laboratory values, 88% of patients treated with IBTROZI experienced increased aspartate aminotransferase (AST), including 10% Grade 3 or 4. Increased alanine aminotransferase (ALT) occurred in 85% of patients treated with IBTROZI, including 13% Grade 3 or 4. The median time to first onset of AST or ALT elevation was 15 days (range: 3 days to 20.8 months). Increased AST or ALT each led to dose interruption in 7% of patients. Increased AST and ALT leading to dose reduction occurred in 5% and 9% of patients, respectively. Increased AST and ALT each led to permanent discontinuation of IBTROZI in 0.3% of patients. Other liver-related adverse reactions leading to permanent discontinuation of IBTROZI were hepatotoxicity (0.6% of patients) and increased bilirubin (0.3% of patients). Concurrent elevations in AST or ALT ≥3 times the upper limit of normal (ULN) and total bilirubin ≥2 times the ULN, with normal alkaline phosphatase, occurred in 2 (0.6%) patients treated with IBTROZI. Fatal liver events occurred in 2 (0.6%) patients. Monitor liver function tests (AST, ALT, and bilirubin) prior to administration of IBTROZI, every 2 weeks during the first 2 months of treatment, and then monthly thereafter as clinically indicated with more frequent testing in patients who develop transaminase elevations. Withhold, then resume at reduced dose upon improvement, or permanently discontinue IBTROZI based on severity [see Dosage and Administration ( 2.4 )] . 5.2 Interstitial Lung Disease/Pneumonitis IBTROZI can cause severe, life-threatening, or fatal interstitial lung disease (ILD) or pneumonitis. In the pooled safety population [see Adverse Reactions ( 6.1 )], interstitial lung disease (ILD)/pneumonitis occurred in 2.3% of patients treated with IBTROZI, including Grade 3 or 4 in 1.1% of patients. The median time to first onset of ILD/pneumonitis was 3.8 months (range: 12 days to 11.8 months). ILD/pneumonitis led to dose interruption of IBTROZI in 1.1% of patients. ILD/pneumonitis required dose reduction in 0.6% of patients and permanent discontinuation of IBTROZI in 0.6% of patients. One fatal ILD case occurred in a patient who received 400 mg once daily dose of IBTROZI. Monitor patients for new or worsening pulmonary symptoms indicative of ILD/pneumonitis. Immediately withhold IBTROZI in patients with suspected ILD/pneumonitis. Withhold, then reduce the dose or permanently discontinue IBTROZI if Grade ≥2 ILD/pneumonitis is confirmed [see Dosage and Administration ( 2.4 )] . 5.3 QTc Interval Prolongation IBTROZI can cause QTc interval prolongation, which can increase the risk for ventricular tachyarrhythmias (e.g., torsades de pointes) or sudden death. IBTROZI prolongs the QTc interval in a concentration-dependent manner [see Clinical Pharmacology ( 12.2 )] . In the pooled safety population [see Adverse Reactions ( 6.1 )], of the 351 patients who underwent at least one post baseline ECG assessment, 13% experienced an increase in QTcF of >60 msec compared to baseline after receiving IBTROZI and 2.6% had an increase in QTcF to >500 msec. Overall, 3.4% of patients had Grade ≥3 QTc interval prolongation. The median time from the first dose of IBTROZI to the onset of ECG QT prolongation was 22 days (range: 1 day to 38.7 months). QTc prolongation led to dose interruption and dose reduction, each in 2.8% of patients treated with IBTROZI. Monitor ECGs and electrolytes prior to administration of IBTROZI, and then periodically thereafter as clinically indicated during treatment. Adjust the frequency of monitoring based on risk factors such as known long QT syndromes, clinically significant bradyarrhythmias, severe or uncontrolled heart failure, and concomitant medications associated with QTc interval prolongation. Significant prolongation of the QTc interval may occur when IBTROZI is taken with food, strong and moderate CYP3A inhibitors, and/or drugs with a known potential to prolong QTc. Administer IBTROZI on an empty stomach. Avoid coadministration of IBTROZI with strong and moderate CYP3A inhibitors and/or drugs with a known potential to prolong QTc [see Dosage and Administration ( 2.3 ), Drug Interactions ( 7.1 , 7.2 )] . Withhold, then resume at the same or reduced dose, or permanently discontinue IBTROZI based on severity [see Dosage and Administration ( 2.4 )] . 5.4 Hyperuricemia IBTROZI can cause hyperuricemia. In the pooled safety population [see Adverse Reactions ( 6.1 )], 14% of patients treated with IBTROZI experienced hyperuricemia reported as an adverse reaction, with 16% of these patients requiring urate-lowering medication without pre-existing gout or hyperuricemia. Hyperuricemia Grade ≥3 occurred in one patient. The median time to first onset of hyperuricemia was 2.1 months (range: 7 days to 35.8 months). Hyperuricemia leading to dose interruption occurred in 0.3% of patients. Monitor serum uric acid levels prior to administration of IBTROZI and periodically during treatment. Initiate treatment with urate-lowering medications as clinically indicated. Withhold, then resume at the same or reduced dose, or permanently discontinue IBTROZI based on severity [see Dosage and Administration ( 2.4 )]. 5.5 Myalgia with Creatine Phosphokinase Elevation IBTROZI can cause myalgia with or without creatine phosphokinase (CPK) elevation. In the pooled safety population [see Adverse Reactions ( 6.1 )], myalgia occurred in 10% of patients treated with IBTROZI. The median time to first onset of myalgia was 11 days (range: 2 days to 10 months). Concurrent myalgia with increased CPK within a 7-day time period was observed in 0.9% of patients. IBTROZI was interrupted in one patient (0.3%) with myalgia, who also presented with concurrent CPK elevation. Advise patients to report any unexplained muscle pain, tenderness, or weakness. Monitor serum CPK levels during IBTROZI treatment every 2 weeks during the first month of treatment and then as clinically indicated in patients reporting unexplained muscle pain, tenderness, or weakness. Withhold, then resume at the same or reduced dose upon improvement [see Dosage and Administration ( 2.4 )]. 5.6 Skeletal Fractures IBTROZI can increase the risk of fractures. ROS1 inhibitors as a class have been associated with skeletal fractures. In the pooled safety population [see Adverse Reactions ( 6.1 )], 3.4% of patients experienced fractures including 1.4% Grade 3. Some fractures occurred in the setting of an accidental fall or other predisposing factors such as osteoporosis, bone metastasis, and age-related degenerative conditions. Fractures involved the ribs (1.4%), spine (0.9%), femur (0.6%), humerus (0.3%), and acetabulum (0.3%). The median time to first onset of fracture was 10.7 months (range: 26 days to 29.1 months). Dose interruption occurred in 0.3% of patients. Promptly evaluate patients with signs or symptoms (e.g., pain, changes in mobility, deformity) of fractures. There are no data on the effects of IBTROZI on healing of known fractures and risk of future fractures. 5.7 Embryo-Fetal Toxicity Based on literature reports in humans with congenital mutations leading to changes in tropomyosin receptor kinase (TRK) signaling, findings from animal studies and its mechanism of action, IBTROZI can cause fetal harm when administered to a pregnant woman. In animal reproduction studies, oral administration of taletrectinib to pregnant rats during the period of organogenesis caused structural abnormalities. Oral administration of taletrectinib to pregnant rabbits during the period of organogenesis resulted in embryo-fetal mortalities and structural abnormalities. Findings in both species occurred at doses resulting in exposures below or equal to the human exposure based on AUC at the recommended dose. Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with IBTROZI and for 3 weeks after the last dose. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with IBTROZI and for 3 weeks after the last dose [see Use in Specific Populations ( 8.1 , 8.3 )] .