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Mirna Releases Phase I Data Showing Manageable Safety Profile for microRNA Rx


NEW YORK (GenomeWeb) – Mirna Therapeutics this week released interim Phase I data showing that its microRNA mimic MRX34 has a manageable safety profile in patients with advanced primary hepatocellular carcinoma (HCC) and other solid tumors with liver involvement, as well as hematological malignancies.

Additionally, treatment was associated with early signals of clinical activity in patients with primary liver, neuroendocrine, colorectal and small cell lung cancers, as well as diffuse large B-cell lymphoma, the company said.

MRX34 is a synthetic version of miR-34a, an miRNA known to play a key role in the p53 tumor-suppressor pathway. Mirna has also said that its own work indicates that miR-34a represses the expression of more than 20 oncogenes and inhibits processes required for cancer cell viability, cancer stemness, metastasis, and chemoresistance.

In mid-2013, the intravenously administered drug entered a Phase I trial in which patients received treatment under one of two dosing schedules: either twice a week for three weeks with one week off in 28-day cycles, or daily for five days with two weeks off in 21-day cycles. Patients in both dosing regimens continue treatment until disease progression or intolerance.

In April, Mirna reported data on 26 patients with unresectable HCC or solid tumors with liver involvement who received treatment under the first dosing schedule, showing that MRX34 was generally safe, although there was one incident of a dose-limiting toxicity.

Now the company has released data from 52 patients showing a manageable safety profile in both dosing schedules. According to Mirna, treatment emergent adverse events primarily consisting of infusion reactions such as fever, chills, nausea, vomiting, and back and flank pain. Pretreatment with the corticosteroid dexamethasone was found to ameliorate these infusion reactions.

Other treatment emergent adverse events included fatigue, diarrhea, headache, dehydration, elevation of liver enzymes, decreased albumin, hyponatremia, lymphopenia, thrombocytopenia, and neutropenia.

The maximum tolerated dose under the trial's first dosing schedule was established at 110 mg/m2. Dose escalation is ongoing for the second regimen.

Although the study is designed to investigate MRX34's safety, tolerability, pharmacokinetics, and dosing regimens, Mirna said that there were preliminary signs of clinical activity. CEO Paul Lammers told GenomeWeb that the company intends to enroll additional HCC patients in the Phase I study, and that he now expects a Phase II trial to begin in the second half of next year.