IRINOTECAN Drug Interactions: What You Need to Know

INTERACTIONS

• Strong CYP3A4 Inducers: Do not administer strong CYP3A4 inducers with irinotecan hydrochloride injection. ( 7.2 )
• Strong CYP3A4 Inhibitors: Do not administer strong CYP3A4 inhibitors with irinotecan hydrochloride injection. ( 7.3 ) 7.1 5-Fluorouracil (5-FU) and Leucovorin (LV) In a phase 1 clinical study involving irinotecan, 5-fluorouracil (5-FU), and leucovorin (LV) in 26 patients with solid tumors, the disposition of irinotecan was not substantially altered when the drugs were co-administered. Although the C max and AUC 0 to 24 of SN-38, the active metabolite, were reduced (by 14% and 8%, respectively) when irinotecan was followed by 5-FU and LV administration compared with when irinotecan was given alone, this sequence of administration was used in the combination trials and is recommended [see Dosage and Administration ( 2 )] . Formal i n vivo or in vitro drug interaction studies to evaluate the influence of irinotecan on the disposition of 5-FU and LV have not been conducted

7.2 Strong CYP3A4 Inducers Exposure to irinotecan or its active metabolite SN-38 is substantially reduced in adult and pediatric patients concomitantly receiving the CYP3A4 enzyme-inducing anticonvulsants phenytoin, phenobarbital, carbamazepine, or St. John's wort. The appropriate starting dose for patients taking these or other strong inducers such as rifampin and rifabutin has not been defined. Consider substituting non-enzyme inducing therapies at least 2 weeks prior to initiation of irinotecan hydrochloride injection therapy. Do not administer strong CYP3A4 inducers with irinotecan hydrochloride injection unless there are no therapeutic alternatives.

7.3 Strong CYP3A4 or UGT1A1 Inhibitors Irinotecan and its active metabolite, SN-38, are metabolized via the human cytochrome P450 3A4 isoenzyme (CYP3A4) and uridine diphosphate-glucuronosyl transferase 1A1 (UGT1A1), respectively, <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.3) ]</span>. Patients receiving concomitant ketoconazole, a CYP3A4 and UGT1A1 inhibitor, have increased exposure to irinotecan and its active metabolite SN-38. Coadministration of irinotecan hydrochloride injection with other inhibitors of CYP3A4 (e.g., clarithromycin, indinavir, itraconazole, lopinavir, nefazodone, nelfinavir, ritonavir, saquinavir, telaprevir, voriconazole) or UGT1A1 (e.g., atazanavir, gemfibrozil, indinavir) may increase systemic exposure to irinotecan or SN-38. Discontinue strong CYP3A4 inhibitors at least 1 week prior to starting irinotecan hydrochloride injection therapy. Do not administer strong CYP3A4 or UGT1A1 inhibitors with irinotecan hydrochloride injection unless there are no therapeutic alternatives.

ONIVYDE is contraindicated in patients who have experienced a severe hypersensitivity reaction or anaphylaxis to ONIVYDE or irinotecan HCl. [see Warnings and Precautions (5.4) , Adverse Reactions (6.2) ]. Severe hypersensitivity reaction to ONIVYDE or irinotecan HCl. ( 4 , 5.4 )

AND PRECAUTIONS

• Diarrhea and Cholinergic Reactions: Early diarrhea (occurring during or shortly after infusion of Irinotecan hydrochloride injection) is usually transient and may be accompanied by cholinergic symptoms. Consider prophylactic or therapeutic administration of 0.25 mg to 1 mg of intravenous or subcutaneous atropine (unless clinically contraindicated). Late diarrhea (generally occurring more than 24 hours after administration of irinotecan hydrochloride injection) can occur. Monitor and replace fluid and electrolytes. Treat with loperamide. Use antibiotic support for ileus and fever. Interrupt irinotecan hydrochloride injection and reduce subsequent doses if severe diarrhea occurs. ( 5.1 )
• Myelosuppression: Manage promptly with antibiotic support. Interrupt irinotecan hydrochloride injection and reduce subsequent doses if necessary. ( 5.2 )
• Patients with Reduced UGT1A1 Activity: Individuals who are homozygous for the UGT1A1*28 allele are at increased risk for neutropenia following initiation of irinotecan hydrochloride injection treatment. ( 5.3 )
• Hypersensitivity: Hypersensitivity reactions including severe anaphylactic or anaphylactoid reactions have been observed. Discontinue irinotecan hydrochloride injection if this occurs. ( 5.4 )
• Renal Impairment/Renal Failure: Rare cases of renal impairment and acute renal failure have been identified, usually in patients who became volume depleted from severe vomiting and/or diarrhea. ( 5.5 )
• Pulmonary Toxicity: Interstitial Pulmonary Disease (IPD)-like events, including fatalities, have occurred. Interrupt for new or progressive dyspnea, cough, and fever pending evaluation. If IPD diagnosed, discontinue and institute appropriate treatment as needed. ( 5.6 )
• Toxicity of the 5 Day Regimen: Irinotecan hydrochloride injection should not be used in combination with a regimen of 5-FU/LV administered for 4-5 consecutive days every 4 weeks outside of a clinical study. ( 5.7 )
• Embryo-Fetal Toxicity: Irinotecan hydrochloride injection can cause fetal harm. Advise females of reproductive potential of the potential risk to a fetus and to use effective contraception. Advise male patients with female partners of reproductive potential to use condoms. ( 5.9 , 8.1 , 8.3 )
• Patients with Hepatic Impairment: In clinical trials, irinotecan hydrochloride injection has not been administered to patients with serum bilirubin >2.0 mg/dL, or transaminases >3 times ULN if no liver metastases, or transaminases >5 times ULN if liver metastases. With the weekly dosage schedule, patients with total bilirubin levels 1.0-2.0 mg/dL had greater likelihood of grade 3-4 neutropenia. ( 5.10 )

5.1 Diarrhea and Cholinergic Reactions Early diarrhea (occurring during or shortly after infusion of Irinotecan hydrochloride injection) is usually transient and infrequently severe. It may be accompanied by cholinergic symptoms of rhinitis, increased salivation, miosis, lacrimation, diaphoresis, flushing, and intestinal hyperperistalsis that can cause abdominal cramping. Bradycardia may also occur. Early diarrhea and other cholinergic symptoms may be prevented or treated. Consider prophylactic or therapeutic administration of 0.25 mg to 1 mg of intravenous or subcutaneous atropine (unless clinically contraindicated). These symptoms are expected to occur more frequently with higher irinotecan doses. Late diarrhea (generally occurring more than 24 hours after administration of irinotecan hydrochloride injection) can be life threatening since it may be prolonged and may lead to dehydration, electrolyte imbalance, or sepsis.

Grade

3-4 late diarrhea occurred in 23-31% of patients receiving weekly dosing. In the clinical studies, the median time to the onset of late diarrhea was 5 days with 3-week dosing and 11 days with weekly dosing. Late diarrhea can be complicated by colitis, ulceration, bleeding, ileus, obstruction, and infection. Cases of megacolon and intestinal perforation have been reported. Patients should have loperamide readily available to begin treatment for late diarrhea. Begin loperamide at the first episode of poorly formed or loose stools or the earliest onset of bowel movements more frequent than normal. One dosage regimen for loperamide is 4 mg at the first onset of late diarrhea and then 2 mg every 2 hours until the patient is diarrhea-free for at least 12 hours. Loperamide is not recommended to be used for more than 48 consecutive hours at these doses, because of the risk of paralytic ileus. During the night, the patient may take 4 mg of loperamide every 4 hours. Monitor and replace fluid and electrolytes. Use antibiotic support for ileus, fever, or severe neutropenia. Subsequent weekly chemotherapy treatments should be delayed in patients until return of pretreatment bowel function for at least 24 hours without anti-diarrhea medication. Patients must not be treated with irinotecan until resolution of the bowel obstruction. If grade 2, 3, or 4 late diarrhea recurs, subsequent doses of irinotecan hydrochloride injection should be decreased [ see Dosage and Administration (2) ]. Avoid diuretics or laxatives in patients with diarrhea.

5.2 Myelosuppression Irinotecan hydrochloride injection can cause severe myelosuppression. Bacterial, viral, and fungal infections have occurred in patients treated with irinotecan hydrochloride injection. Deaths due to sepsis following severe neutropenia have been reported in patients treated with irinotecan hydrochloride injection. In the clinical studies evaluating the weekly dosage schedule, neutropenic fever (concurrent NCI grade 4 neutropenia and fever of grade 2 or greater) occurred in 3% of the patients; 6% of patients received G-CSF for the treatment of neutropenia. Manage febrile neutropenia promptly with antibiotic support [ see Warnings and Precautions (5.2) ]. Hold irinotecan hydrochloride injection if neutropenic fever occurs or if the absolute neutrophil count drops &lt;1000/mm 3 . After recovery to an absolute neutrophil count ≥1000/mm 3 , subsequent doses of irinotecan hydrochloride injection should be reduced [ see Dosage and Administration (2) ]. When evaluated in the trials of weekly administration, the frequency of grade 3 and 4 neutropenia was higher in patients who received previous pelvic/abdominal irradiation than in those who had not received such irradiation (48% [13/27] versus 24% [67/277]; p=0.04). Patients who have previously received pelvic/abdominal irradiation are at increased risk of severe myelosuppression following the administration of irinotecan hydrochloride injection. Based on sparse available data, the concurrent administration of irinotecan hydrochloride injection with irradiation is not recommended. Patients with baseline serum total bilirubin levels of 1.0 mg/dL or more also had a greater likelihood of experiencing first-cycle grade 3 or 4 neutropenia than those with bilirubin levels that were less than 1.0 mg/dL (50% [19/38] versus 18% [47/266]; p&lt;0.001). Patients with deficient glucuronidation of bilirubin, such as those with Gilbert’s syndrome, may be at greater risk of myelosuppression when receiving therapy with irinotecan hydrochloride injection.

5.3 Patients With Reduced UGT1A1 Activity Individuals who are homozygous for the UGT1A1*28 allele (UGT1A1 7/7 genotype) are at increased risk for neutropenia following initiation of irinotecan hydrochloride injection treatment. In a study of 66 patients who received single-agent irinotecan hydrochloride injection (350 mg/m 2 once-every-3-weeks), the incidence of grade 4 neutropenia in patients homozygous for the UGT1A1*28 allele was 50%, and in patients heterozygous for this allele (UGT1A1 6/7 genotype) the incidence was 12.5%. No grade 4 neutropenia was observed in patients homozygous for the wild-type allele (UGT1A1 6/6 genotype). In a prospective study (n=250) to investigate the role of UGT1A1*28 polymorphism in the development of toxicity in patients treated with irinotecan hydrochloride injection (180 mg/m 2 ) in combination with infusional 5-FU/LV, the incidence of grade 4 neutropenia in patients homozygous for the UGT1A1*28 allele was 4.5%, and in patients heterozygous for this allele the incidence was 5.3%.

Grade

4 neutropenia was observed in 1.8% of patients homozygous for the wild-type allele. In another study in which 109 patients were treated with irinotecan hydrochloride injection (100 to 125 mg/m 2 ) in combination with bolus 5-FU/LV, the incidence of grade 4 neutropenia in patients homozygous for the UGT1A1*28 allele was 18.2%, and in patients heterozygous for this allele the incidence was 11.1%.

Grade

4 neutropenia was observed in 6.8% of patients homozygous for the wild-type allele. When administered in combination with other agents or as a single-agent, a reduction in the starting dose by at least one level of irinotecan hydrochloride injection should be considered for patients known to be homozygous for the UGT1A1*28 allele. However, the precise dose reduction in this patient population is not known and subsequent dose modifications should be considered based on individual patient tolerance to treatment [ see Dosage and Administration (2) ]. UGT1A1 Testing A laboratory test is available to determine the UGT1A1 status of patients. Testing can detect the UGT1A1 6/6, 6/7 and 7/7 genotypes.

5.4 Hypersensitivity Hypersensitivity reactions including severe anaphylactic or anaphylactoid reactions have been observed. Discontinue irinotecan hydrochloride injection if anaphylactic reaction occurs.

5.5 Renal Impairment/Renal Failure Renal impairment and acute renal failure have been identified, usually in patients who became volume depleted from severe vomiting and/or diarrhea.

5.6 Pulmonary Toxicity Interstitial Pulmonary Disease (IPD)-like events, including fatalities, have occurred in patients receiving irinotecan (in combination and as monotherapy). Risk factors include pre-existing lung disease, use of pneumotoxic drugs, radiation therapy, and colony stimulating factors. Patients with risk factors should be closely monitored for respiratory symptoms before and during irinotecan therapy.

In

Japanese studies, a reticulonodular pattern on chest x-ray was observed in a small percentage of patients. New or progressive, dyspnea, cough, and fever should prompt interruption of chemotherapy, pending diagnostic evaluation. If IPD is diagnosed, irinotecan and other chemotherapy should be discontinued and appropriate treatment instituted as needed [ see Adverse Reactions (6.1) ].

5.7 Toxicity of the 5 Day Regimen Outside of a well-designed clinical study, irinotecan hydrochloride injection should not be used in combination with a regimen of 5-FU/LV administered for 4-5 consecutive days every 4 weeks because of reports of increased toxicity, including toxic deaths. Irinotecan hydrochloride injection should be used as recommended in Table 2 [ see Dosage and Administration (2) ].

5.8 Increased Toxicity in Patients with Performance Status 2 In patients receiving either irinotecan/5-FU/LV or 5-FU/LV in the clinical trials, higher rates of hospitalization, neutropenic fever, thromboembolism, first-cycle treatment discontinuation, and early deaths were observed in patients with a baseline performance status of 2 than in patients with a baseline performance status of 0 or 1.

5.9 Embryo-Fetal Toxicity Based on its mechanism of action and findings in animals, Irinotecan hydrochloride injection can cause fetal harm when administered to a pregnant woman. In animal studies, intravenous administration of irinotecan during the period of organogenesis resulted in embryofetal mortality and teratogenicity in pregnant animals at exposures lower than the human exposure based on area under the curve (AUC) at the clinical dose of 125 mg/m 2 . Advise pregnant women of the potential risk to a fetus. Advise female patients of reproductive potential to avoid becoming pregnant and to use highly effective contraception during treatment with irinotecan hydrochloride injection and for 6 months after the final dose. Advise male patients with female partners of reproductive potential to use condoms during treatment and for 3 months after the final dose of irinotecan hydrochloride injection <span class="opacity-50 text-xs">[see Use in Specific Populations (8.1) , ( 8.3 ) and Nonclinical Toxicology (13.1) ]</span> .

5.10 Patients with Hepatic Impairment The use of irinotecan hydrochloride injection in patients with significant hepatic impairment has not been established. In clinical trials of either dosing schedule, irinotecan was not administered to patients with serum bilirubin &gt;2.0 mg/dL, or transaminase &gt;3 times the upper limit of normal if no liver metastasis, or transaminase &gt;5 times the upper limit of normal with liver metastasis. In clinical trials of the weekly dosage schedule, patients with modestly elevated baseline serum total bilirubin levels (1.0 to 2.0 mg/dL) had a significantly greater likelihood of experiencing first-cycle, grade 3 or 4 neutropenia than those with bilirubin levels that were less than 1.0 mg/dL (50% [19/38] versus 18% [47/226]; p&lt;0.001) [ see Dosage and Administration (2.1) , Use in Specific Populations (8.7) and Clinical Pharmacology (12.3) ].