Neratinib

Risk Summary

Based on findings from animal studies and the mechanism of action, neratinib can cause fetal harm when administered to a pregnant woman.

There are no available data in pregnant women to inform the drug-associated risk. In animal reproduction studies, administration of neratinib to pregnant rabbits during organogenesis resulted in abortions, embryo-fetal death and fetal abnormalities in rabbits at maternal exposures (AUC) approximately 0.2 times exposures in patients at the recommended dose (see Data). Advise pregnant women of the potential risk to a fetus.

The background risk of major birth defects and miscarriage for the indicated population is unknown. However, the background risk of major birth defects is 2%–4% and of miscarriage is 15%–20% of clinically recognized pregnancies in the U.S. general population.

Data

Animal Data

In a fertility and early embryonic development study in female rats, neratinib was administered orally for 15 days before mating to Day 7 of pregnancy, which did not cause embryonic toxicity at doses up to 12 mg/kg/day in the presence of maternal toxicity. A dose of 12 mg/kg/day in rats is approximately 0.5 times the maximum recommended dose of 240 mg/day in patients on a mg/m² basis.

In an embryo-fetal development study in rats, pregnant animals received oral doses of neratinib up to 15 mg/kg/day during the period of organogenesis. No effects on embryo-fetal development or survival were observed. Maternal toxicity was evident at 15 mg/kg/day (approximately 0.6 times the AUC in patients receiving the maximum recommended dose of 240 mg/day).

In an embryo-fetal development study in rabbits, pregnant animals received oral doses of neratinib up to 9 mg/kg/day during the period of organogenesis. Administration of neratinib at doses ≥6 mg/kg/day resulted in maternal toxicity, abortions, and embryo-fetal death (increased resorptions). Neratinib administration resulted in increased incidence of fetal gross external (domed head), soft tissue (dilation of the brain ventricles and ventricular septal defect), and skeletal (misshapen anterior fontanelles and enlarged anterior and/or posterior fontanelles) abnormalities at ≥3 mg/kg/day. The AUC_(0-t) at 6 mg/kg/day and 9 mg/kg/day in rabbits were approximately 0.5 and 0.8 times, respectively, the AUCs in patients receiving the maximum recommended dose of 240 mg/day.

In a peri- and postnatal development study in rats, oral administration of neratinib from gestation day 7 until lactation day 20 resulted in maternal toxicity at ≥10 mg/kg/day (approximately 0.4 times the maximum recommended dose of 240 mg/day in patients on a mg/m² basis) including decreased body weights, body weight gains, and food consumption. Effects on long-term memory were observed in male offspring at maternal doses ≥5 mg/kg/day (approximately 0.2 times the maximum recommended dose of 240 mg/day in patients on a mg/m² basis).

Risk Summary

No data are available regarding the presence of neratinib or its metabolites in human milk or its effects on the breastfed infant or on milk production. Because of the potential for serious adverse reactions in breastfed infants from neratinib, advise lactating women not to breastfeed while taking neratinib and for at least 1 month after the last dose.

A two-year carcinogenicity study was conducted in rats at oral neratinib doses of 1, 3, and 10 mg/kg/day. Neratinib was not carcinogenic in male and female rats at exposure levels >25 times the AUC in patients receiving the maximum recommended dose of 240 mg/day. Neratinib was not carcinogenic in a 26-week study in Tg.rasH2 transgenic mice when administered daily by oral gavage at doses up to 50 mg/kg/day in males and 125 mg/kg/day in females.

Neratinib was not mutagenic in an in vitro bacterial reverse mutation (AMES) assay or clastogenic in an in vitro human lymphocyte chromosomal aberration assay or an in vivo rat bone marrow micronucleus assay.

In a fertility study in rats, neratinib administration up to 12 mg/kg/day (approximately 0.5 times the maximum recommended dose of 240 mg/day in patients on a mg/m² basis) caused no effects on mating or the ability of animals to become pregnant. In repeat-dose toxicity studies in dogs with oral administration of neratinib daily for up to 39 weeks, tubular hypoplasia of the testes was observed at ≥0.5 mg/kg/day. This finding was observed at AUCs that were approximately 0.4 times the AUC in patients at the maximum recommended dose of 240 mg.

• Diarrhea
• Hepatotoxicity

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Extended Adjuvant Treatment of Early Stage Breast Cancer

ExteNET

The data described below reflect the safety data of neratinib as a single agent in ExteNET a multicenter, randomized, double-blind, placebo-controlled study of neratinib within 2 years after completion of adjuvant treatment with trastuzumab-based therapy in women with HER2-positive early-stage breast cancer. Patients who received neratinib in this trial were not required to receive any prophylaxis with antidiarrheal agents to prevent the neratinib-related diarrhea. Patients were treated with 240 mg of neratinib given orally once daily with food, continuously until disease recurrence or for up to one year. The median duration of treatment was 11.6 months in the neratinib arm and 11.8 months in the placebo arm. The median age was 52 years (60% were ≥50 years old, 12% were ≥65 years old); 81% were Caucasian, 3% Black or African American, 14% Asian, and 3% other. A total of 1408 patients were treated with neratinib.

Neratinib dose reduction due to an adverse reaction of any grade occurred in 31% of patients receiving neratinib compared to 2.6% of patients receiving placebo. Permanent discontinuation due to any adverse reaction was reported in 28% of neratinib-treated patients. The most common adverse reaction leading to discontinuation was diarrhea, accounting for 17% of neratinib-treated patients.

The most common adverse reactions (≥5%) were diarrhea, nausea, abdominal pain, fatigue, vomiting, rash, stomatitis, decreased appetite, muscle spasms, dyspepsia, AST or ALT increased, nail disorder, dry skin, abdominal distention, epistaxis, weight decreased, and urinary tract infection. The most frequently reported Grade 3 or 4 adverse reactions were diarrhea, vomiting, nausea, and abdominal pain.

Serious adverse reactions in the neratinib arm included diarrhea (1.6%), vomiting (0.9%), dehydration (0.6%), cellulitis (0.4%), renal failure (0.4%), erysipelas (0.4%), ALT (0.3%), AST increased (0.3%), nausea (0.3%), fatigue (0.2%), and abdominal pain (0.2%).

Table 1 summarizes the adverse reactions in ExteNET.

Table 1. Adverse Reactions Reported in ≥2% of Neratinib-Treated Patients in ExteNET:

* Includes abdominal pain, abdominal pain upper, and abdominal pain lower
^† Includes stomatitis, aphthous stomatitis, mouth ulceration, oral mucosal blistering, mucosal inflammation, oropharyngeal pain, oral pain, glossodynia, glossitis, and cheilitis
^‡ Includes rash, rash erythematous, rash follicular, rash generalized, rash pruritic, rash pustular, rash maculo-papular, rash papular, dermatitis, dermatitis acneiform, and toxic skin eruption
^§ Includes nail disorder, paronychia, onychoclasis, nail discoloration, nail toxicity, nail growth abnormal, and nail dystrophy

Advanced or Metastatic Breast Cancer

NALA

The data described below reflect the safety data of neratinib plus capecitabine in NALA, a randomized, multicenter, multinational, open-label, active-controlled study of HER2+ metastatic breast cancer in patients, with or without brain metastases, who have received two or more prior anti HER2-based regimens in the metastatic setting.

Patients were treated with NERLNX 240 mg orally once daily Days 1–21 of a 21-day cycle in combination with capecitabine (750 mg/m² given orally twice daily) Days 1–14 of a 21-day cycle or lapatinib 1250 mg orally once daily Days 1–21 of a 21-day cycle in combination with capecitabine (1000 mg/m² given orally twice daily) Days 1–14 of a 21-day cycle until disease progression. The median duration of treatment was 5.7 months in the neratinib plus capecitabine arm and 4.4 months in the lapatinib plus capecitabine arm.

Neratinib dose reduction due to an adverse reaction of any grade occurred in 10% of patients receiving neratinib plus capecitabine. Permanent discontinuation due to any adverse reaction was reported in 14% of neratinib plus capecitabine treated patients. The most common adverse reactions leading to discontinuation were vomiting (3.6%), diarrhea (2.6%), nausea (2.6%), and palmar-plantar erythrodysaesthesia syndrome (2.3%) of neratinib plus capecitabine -treated patients.

The most common adverse reactions of any grade (≥5%) in the neratinib plus capecitabine arm were diarrhea, nausea, vomiting, decreased appetite, constipation, fatigue/asthenia, weight decreased, dizziness, back pain, arthralgia, urinary tract infection, upper respiratory tract infection, abdominal distention, renal impairment, and muscle spasms. The most frequently reported Grade 3 or 4 adverse reactions were diarrhea, nausea, vomiting, fatigue, and decreased appetite.

Serious adverse reactions ≥2% in the neratinib plus capecitabine arm included diarrhea (7%), vomiting (3%), nausea (2.3%), and acute kidney injury (2.3%).

Table 2 summarizes the adverse reactions in NALA.

Table 2. Adverse Reactions Reported in ≥2% of Neratinib-Treated Patients in Combination with Capecitabine in NALA:

* Renal impairment includes acute kidney injury, blood creatinine increased, renal failure, and renal impairment

CONTROL

The CONTROL (NCT02400476) study was a multicenter, open-label, multi-cohort trial evaluating patients with early stage HER2-positive breast cancer treated with neratinib 240 mg daily for up to one year receiving loperamide prophylaxis with and without an additional anti-diarrheal treatment. All patients received loperamide 4 mg loading dose, followed by 4 mg three times a day from Days 1–14, followed by 4 mg twice a day on Days 15–56, followed by loperamide as needed through 1 year of treatment with neratinib. One cohort of patients received budesonide 9 mg once daily on cycle 1 Days 1–28, in addition to loperamide. At the interim analysis, the incidence of all grade diarrhea for patients receiving loperamide alone (n=109) was 78% compared to 86% of patients who received budesonide and loperamide (n=64). The incidence of Grade 2 diarrhea was 25% compared to 33%, respectively. The incidence of Grade 3 diarrhea was 32% compared to 28%, respectively. Diarrhea leading to treatment discontinuation occurred in 18% of patients treated with loperamide alone compared to 11% of the patients who received loperamide and budesonide.