| toxicity summary | IDENTIFICATION AND USE: Pomalidomide is a solid yellow powder. Pomalidomide, a thalidomide analog, is an immunomodulatory agent with antineoplastic and antiangiogenic activity. It is used in patients with multiple myeloma who have received at least two prior therapies including lenalidomide and bortezomib and have demonstrated disease progression on or within 60 days of completion of the last therapy. HUMAN EXPOSURE AND TOXICITY: Pomalidomide may cause fetal toxicity; it is a structural analog of thalidomide, a known human teratogen. Therefore, pomalidomide is contraindicated during pregnancy. Acute myelogenous leukemia has been reported in patients receiving pomalidomide as investigational therapy for uses other than multiple myeloma. Serious venous thromboembolic events have also been reported in patients receiving pomalidomide. Pomalidomide did not induce chromosomal aberrations in human peripheral blood lymphocytes. ANIMAL STUDIES: Chronic administration of pomalidomide was well tolerated in rats at doses of 50, 250 and 1000 mg/kg/day for 6 months. However, monkeys exhibited greater sensitivity to pomalidomide in the studies reported. The primary toxicities observed in monkeys were associated with the hematopoietic/lymphoreticular systems. In the 9-month study in monkeys with doses of 0.05, 0.1, and 1 mg/kg/day, morbidity and early euthanasia of 6 animals were observed at the dose of 1 mg/kg/day and were attributed to immunosuppressive effects at high exposures of pomalidomide. These immunosuppressive effects resulted in early euthanasia of 4 monkeys due to poor health condition ; histopathological evaluation of these animals showed chronic inflammation of the large intestine and villous atrophy of the small intestine. Staphylococcal infection was observed in 4 monkeys; 3 of these animals responded to antibiotic treatment and 1 died without treatment. In addition, findings consistent with acute myelogenous leukemia led to euthanasia of 1 monkey; clinical observations and clinical pathology and/or bone marrow alterations observed in this animal were consistent with immunosuppression. Minimal or mild bile duct proliferation with associated increases in ALP and GGT were also observed at 1 mg/kg/day. Evaluation of recovery animals indicated that all treatment-related findings were reversible after 8 weeks of dosing cessation, except for proliferation of intrahepatic bile ducts observed in 1 animal in the 1 mg/kg/day group. Pomalidomide was teratogenic in rabbits when administered during the period of major organogenesis. Doses ranging from 10 to 250 mg/kg produced embryo-fetal developmental malformations and variations. Increased cardiac anomalies and skeletal malformations were seen at all dose levels. At 100 and 250 mg/kg/day, there were slight increases in post-implantation loss and slight decreases in fetal body weights. At 100 and/or 250 mg/kg/day, fetal malformations also included limb anomalies and associated skeletal deformities, moderate dilation of the lateral ventricle in the brain, abnormal placement of the right subclavian artery, absent intermediate lobe in the lungs, low-set kidney, altered liver morphology, incompletely or not ossified pelvis, an increased average for supernumerary thoracic ribs and a reduced average for ossified tarsals. Pomalidomide was also teratogenic in rats. Malformations such as the absence of urinary bladder, absence of thyroid gland, and fusion and misalignment of lumbar and thoracic vertebral elements sometimes associated with discontinuous and misshapen ribs were observed at all dosage levels . In a fertility and early embryonic development study in rats, pomalidomide was administered to male and female rats at doses of 25, 250, and 1000 mg/kg/day before, during, and after mating with animals at the same dose level. Uterine examination on Gestation Day 13 showed a decrease in mean number of viable embryos and an increase in postimplantation loss at all dose levels. Pomalidomide was not mutagenic in bacterial and mammalian mutation Ames assays, and did not induce micronuclei formation in polychromatic erythrocytes in bone marrow of rats administered doses up to 2000 mg/kg/day. |
