Midostaurin (Rydapt) is a new drug approved by the Food and Drug Administration (FDA) to treat adults with newly diagnosed acute myeloid leukemia (AML) who have a mutation in the FLT3 gene. It is to be used in combination with standard AML chemotherapy. The drug is also approved for use with a companion diagnostic, LeukoStrat CDx FLT3 Mutation Assay, which is used to detect the genetic mutation. Midostaurin is also approved to treat aggressive systemic mastocytosis, systemic mastocytosis with associated hematologic neoplasm, and mast cell leukemia, all rare blood disorders.
Midostaurin is an oral multiple receptor tyrosinekinase inhibitor. It inhibits FLT3-receptor signaling and cell proliferation and produces cell death in leukemic cells with the FLT3 mutation. Midostaurin also inhibits signaling, cell proliferation, and histamine release in mast cells, and induces mast cell death.
The most frequent adverse effects of midostaurin when used to treat AML are febrile neutropenia, nausea, mucositis, vomiting, headache, petechiae, musculoskeletal pain, epistaxis, device-related infections, hyperglycemia, and upper respiratory tract infection. The most frequent adverse effects of midostaurin when used in the treatment of rare blood disorders include nausea, vomiting, diarrhea, edema, musculoskeletal pain, abdominal pain, fatigue, upper respiratory tract infection, constipation, fever, headache, and shortness of breath. Pulmonary toxicity (interstitial lung disease and pneumonitis) has been noted in some patients treated with midostaurin. Some of the affected patients died. Nurses should monitor patients for pulmonary symptoms and consult with the prescribing clinician if patients demonstrate signs or symptoms of these respiratory toxicities, and the drug should be discontinued.
Regorafenib (Stivarga), a kinase inhibitor, is now approved to treat hepatocellular carcinoma that is no longer responding to treatment with sorafenib (Nexavar), the standard drug therapy. Regorafenib was previously approved to treat colorectal cancer and gastrointestinal stromal tumors that no longer respond to initial treatments.
The adverse effect profile for regorafenib is similar for all of its therapeutic applications. The drug carries a black box warning that severe and sometimes fatal hepatotoxicity has occurred in clinical trials. Other serious adverse effects listed as warnings and precautions for regorafenib therapy include infections, hemorrhage, gastro-intestinal perforation or fistula, dermatologic toxicity, hypertension (possibly severe and uncontrollable), cardiac ischemia and infarction, reversible posterior leukoencephalopathy syndrome, wound healing complications, and embryo-fetal toxicity. Complete prescribing information for midostaurin can be found at http://bit.ly/2rnVFNu. Complete prescribing information for regorafenib can be found at http://bit.ly/2sxeT3m.