Omacetaxine mepesuccinate

Risk Summary

Based on its mechanism of action and findings from animal studies, omacetaxine mepesuccinate can cause fetal harm when administered to pregnant women. In animal reproduction studies, subcutaneous administration of omacetaxine mepesuccinate to pregnant mice during organogenesis at doses approximately 0.25-0.5 times the maximum recommended human doses (MRHD) resulted in embryo-fetal mortality, structural abnormalities, and alterations to growth (see Data). There are no available data on omacetaxine mepesuccinate use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. Advise pregnant women of the potential risk to a fetus.

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.

Data

Animal Data

In an embryo-fetal development study, pregnant mice were administered omacetaxine mepesuccinate subcutaneously during the period of organogenesis at doses of 0.63 or 1.23 mg/m²/day (approximately 0.25-0.5 times the MRHD on a body surface area basis). Drug-related adverse effects included embryonic death, an increase in unossified bones/reduced bone ossification, and decreased fetal body weights. Fetal toxicity occurred at doses of 1.23 mg/m²/day, which is approximately half the recommended daily human dose.

Risk Summary

There are no data on the presence of omacetaxine mepesuccinate in either human or animal milk, the effects on the breastfed child, or the effects on milk production. Because of the potential for serious adverse reactions in the breastfed child, advise patients that breastfeeding is not recommended during treatment with omacetaxine mepesuccinate, and for 2 weeks after the final dose.

No carcinogenicity studies have been conducted with omacetaxine mepesuccinate.

Omacetaxine mepesuccinate was genotoxic in an in vitro chromosomal aberration test system in Chinese hamster ovary (CHO) cells, but was not mutagenic when tested in an in vitro bacterial cell assay (Ames test), and it did not induce genetic damage using an in vivo mouse micronucleus assay.

Omacetaxine mepesuccinate may impair male fertility. Studies in mice demonstrated adverse effects on male reproductive organs. Bilateral degeneration of the seminiferous tubular epithelium in testes and hypospermia/aspermia in the epididymides were reported in the highest dose group (2.33 mg/kg/day reduced to 1.67 mg/kg/day; 7 to 5 mg/m²/day) following subcutaneous injection of omacetaxine mepesuccinate for six cycles over six months. The doses used in the mice were approximately two to three times the recommended daily human dose based on body surface area.

The following clinically significant adverse reactions have been associated with omacetaxine mepesuccinate in clinical trials.

• Myelosuppression
• Bleeding
• Hyperglycemia

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.

The safety data for omacetaxine mepesuccinate are from 3 clinical trials which enrolled a total of 163 adult patients with TKI resistant and/or intolerant chronic phase (N=108) and accelerated phase (N=55) CML. All patients were treated with initial induction therapy consisting of a dose of 1.25 mg/m² administered subcutaneously twice daily for 14 consecutive days every 28 days (induction cycle). Responding patients were then treated with the same dose and a twice daily schedule for 7 consecutive days every 28 days (maintenance cycle).

Chronic Phase CML

The median duration of exposure for the 108 patients with chronic phase CML was 7.4 months (range 0 to 43 months). The median total cycles of exposure was 6 (range 1 to 41), and the median total dose delivered during the trials was 131 mg/m² (range 1.2 to 678). Among the patients with chronic phase CML, 87% received 14 days of treatment during cycle 1. By cycles 2 and 3, the percentage of patients receiving 14 days of treatment decreased to 42% and 16% respectively. Of the 91 patients who received at least 2 cycles of treatment, 79 (87%) had at least 1 cycle delay during the trials. The median number of days of cycle delays was greatest for cycle 2 (17 days) and cycle 3 (25 days) when more patients were receiving induction cycles.

Adverse reactions were reported for 99% of the patients with chronic phase CML. A total of 18% of patients had adverse reactions leading to withdrawal. The most frequently occurring adverse reactions leading to discontinuation were pancytopenia, thrombocytopenia, and increased alanine aminotransferase (each 2%). A total of 87% of patients reported at least 1 Grade 3 or Grade 4 treatment emergent adverse reaction (Table 1).

Table 1. Adverse Reactions Occurringa in at Least 10% of Patients (Chronic Myeloid Leukemia – Chronic Phase):

^a Occurred in the period between the first dose and 30 days after the last dose.
^b Includes infusion related reaction, injection site erythema, injection site hematoma, injection site hemorrhage, injection site hypersensitivity, injection site induration, injection site inflammation, injection site irritation, injection site mass, injection site edema, injection site pruritus, injection site rash, and injection site reaction.
^c Infection includes bacterial, viral, fungal, and non-specified.

Serious adverse reactions were reported for 51% of patients. Serious adverse reactions reported for at least 5% of patients were bone marrow failure and thrombocytopenia (each 10%), and febrile neutropenia (6%). Serious adverse reactions of infections were reported for 8% of patients.

Deaths occurred while on study in five (5%) patients with CP CML. Two patients died due to cerebral hemorrhage, one due to multi-organ failure, one due to progression of disease, and one from unknown causes.

Accelerated Phase CML

Median total cycles of exposure was 2 (range 1 to 29), and the median total dose delivered during the trials was 70 mg/m². The median duration of exposure for the 55 patients with accelerated phase CML was 1.9 months (range 0 to 30 months). Of the patients with accelerated phase CML, 86% received 14 days of treatment during cycle 1. By cycles 2 and 3, the percentage of patients receiving 14 days of treatment decreased to 55% and 44% respectively. Of the 40 patients who received at least 2 cycles of treatment, 27 (68%) had at least 1 cycle delay during the trials. The median number of days of cycle delays was greatest for cycle 3 (31 days) and cycle 8 (36 days).

Adverse reactions regardless of investigator attribution were reported for 100% patients with accelerated phase CML. A total of 33% of patients had adverse reactions leading to withdrawal. The most frequently occurring adverse reactions leading to withdrawal were leukocytosis (6%), and thrombocytopenia (4%). A total of 84% of patients reported at least 1 Grade 3 or Grade 4 treatment emergent adverse reaction (Table 2).

Table 2. Adverse Reactions Occurringa in at Least 10% of Patients (Chronic Myeloid Leukemia – Accelerated Phase):

^a Occurred in the period between the first dose and 30 days after the last dose.
^b Includes infusion related reaction, injection site erythema, injection site hematoma, injection site hemorrhage, injection site hypersensitivity, injection site induration, injection site inflammation, injection site irritation, injection site mass, injection site edema, injection site pruritus, injection site rash, and injection site reaction.
^c Infection includes bacterial, viral, fungal, and non-specified.

Serious adverse reactions were reported for 60% of patients. Serious adverse reactions reported for at least 5% of patients were febrile neutropenia (18%), thrombocytopenia (9%), anemia (7%), and diarrhea (6%). Serious adverse reactions of infections were reported for 11% of patients.

Death occurred while on study in 5 (9%) patients with AP CML. Two patients died due to cerebral hemorrhage and three due to progression of disease.

Laboratory Abnormalities in Chronic and Accelerated Phase CML

Grade ¾ laboratory abnormalities reported in patients with chronic and accelerated phase CML are described in Table 3. Myelosuppression occurred in all patients treated with omacetaxine mepesuccinate. Five patients with chronic phase CML and 4 patients with accelerated phase CML permanently discontinued omacetaxine mepesuccinate due to pancytopenia, thrombocytopenia, febrile neutropenia, or bone marrow necrosis. An event of hyperosmolar non-ketotic hyperglycemia was reported in one patient in the safety population and a similar case has been reported in the literature. Two patients with chronic phase CML permanently discontinued omacetaxine mepesuccinate due to elevated transaminases.

Table 3. Grade ¾ Laboratory Abnormalities in Clinical Studies in Patients with Chronic Phase and Accelerated Phase CML:

6.2 Additional Data from Safety Population

The following adverse reactions were reported in patients in the omacetaxine mepesuccinate clinical studies of patients with chronic phase and accelerated phase CML at a frequency of 1% to less than 10%. Within each category, adverse reactions are ranked on the basis of frequency.

Cardiac Disorders: tachycardia, palpitations, acute coronary syndrome, angina pectoris, arrhythmia, bradycardia, ventricular extrasystoles.

Ear and Labyrinth Disorders: ear pain, ear hemorrhage, tinnitus.

Eye Disorders: cataract, vision blurred, conjunctival hemorrhage, dry eye, lacrimation increased, conjunctivitis, diplopia, eye pain, eyelid edema.

Gastrointestinal Disorders: stomatitis, mouth ulceration, abdominal distension, dyspepsia, gastroesophageal reflux disease, gingival bleeding, aphthous stomatitis, dry mouth, hemorrhoids, gastritis, gastrointestinal hemorrhage, melena, mouth hemorrhage, oral pain, anal fissure, dysphagia, gingival pain, gingivitis.

General Disorders and Administration Site Conditions: mucosal inflammation, pain, chest pain, hyperthermia, influenza-like illness, catheter site pain, general edema, malaise.

Immune System Disorders: hypersensitivity.

Injury, Poisoning and Procedural Complications: contusion, transfusion reaction.

Metabolism and Nutrition Disorders: decreased appetite, diabetes mellitus, gout, dehydration.

Musculoskeletal and Connective Tissue Disorders: bone pain, myalgia, muscular weakness, muscle spasms, musculoskeletal chest pain, musculoskeletal pain, musculoskeletal stiffness, musculoskeletal discomfort.

Nervous System Disorders: dizziness, cerebral hemorrhage, paresthesia, convulsion, hypoesthesia, lethargy, sciatica, burning sensation, dysgeusia, tremor.

Psychiatric Disorders: anxiety, depression, agitation, confusional state, mental status change.

Renal and Urinary Disorders: dysuria.

Respiratory, Thoracic and Mediastinal Disorders: pharyngolaryngeal pain, nasal congestion, dysphonia, productive cough, rales, rhinorrhea, hemoptysis, sinus congestion.

Skin and Subcutaneous Tissue Disorders: erythema, pruritus, dry skin, petechiae, hyperhidrosis, night sweats, ecchymosis, purpura, skin lesion, skin ulcer, rash erythematous, rash papular, skin exfoliation, skin hyperpigmentation.

Vascular Disorders: hematoma, hypertension, hot flush, hypotension.