Genzyme, Isis announce results of two mipomersen phase 3 studies

Aug 5 2010

Genzyme Corp. (NASDAQ: GENZ) and Isis Pharmaceuticals Inc. (NASDAQ: ISIS) today announced results of two phase 3 studies of mipomersen in patients who had high cholesterol levels while on maximally tolerated lipid-lowering therapy. In the study of patients with severe hypercholesterolemia, mipomersen reduced LDL-C, the primary endpoint, by 36 percent compared with a 13 percent increase for placebo. In the study of patients with high cholesterol at high cardiovascular risk, mipomersen reduced LDL-C by 37 percent compared with a 5 percent reduction for placebo. Both studies met all of their secondary endpoints. Frequently observed adverse events were injection site reactions, flu-like symptoms and elevations in liver transaminases, as seen in previous studies.

“For these high risk patients, there exists a tremendous need for additional lipid lowering therapies.”

With these studies, the companies have completed the four phase 3 studies that are planned to be included in the initial U.S. and E.U. regulatory filings for mipomersen. These filings, expected in the first half of 2011, will seek approval for the treatment of patients with homozygous familial hypercholesterolemia (FH), and may also include patients with severe hypercholesterolemia. The two previous phase 3 studies of mipomersen, which focused on patients with homozygous and heterozygous FH, also met their primary and secondary endpoints.

"We are pleased with the robust efficacy of mipomersen across all four phase 3 trials. These data, along with the emerging safety profile, support our focused approach on patients at highest cardiovascular risk who are in the greatest need of new treatments," said Genzyme Senior Vice President John Butler. "With completion of these studies, we remain on-track with our plans for mipomersen."

Phase 3 Study in Patients with Severe Hypercholesterolemia

This double-blind, placebo-controlled trial included 58 patients with severe hypercholesterolemia who were already taking maximally tolerated lipid-lowering medications. Severe hypercholesterolemia patients were defined as those who have LDL-C levels ≥ 200 mg/dL with baseline cardiovascular disease (CVD) or LDL-C levels ≥ 300 mg/dL without CVD. Patients were randomized 2:1 to receive a 200 mg dose of mipomersen or placebo weekly for 26 weeks. This study was conducted at 26 sites in North America, Europe and South Africa.

Patients treated with mipomersen had an average LDL-C at baseline of 276 mg/dL. At the end of the trial, these patients had an average LDL-C level of 175 mg/dL, representing an average LDL-C reduction of 101 mg/dL (36 percent). The reductions observed in the study were in addition to those achieved with the patients' existing maximally tolerated lipid-lowering regimens. The trial also met each of its three secondary endpoints with statistically significant reductions in apo-B, non-HDL-cholesterol and total cholesterol. Study results are based on an intent-to-treat analysis (full analysis set). Detailed results will be submitted for presentation at a medical meeting.

Of the 39 patients treated with mipomersen, 27 completed treatment; of the 19 patients treated with placebo, 18 completed treatment. Eight of the discontinuations in the mipomersen group were reported as being related to adverse events, the nature of which was generally similar to previous studies. The placebo discontinuation was reported as being related to an adverse event. There was one death in the study due to acute coronary syndrome in a patient treated with mipomersen that was reported as unrelated to treatment.

Elevations in liver transaminases (ALTs) in patients treated with mipomersen were observed that were generally similar in character with those seen in other studies. In this study, 15 percent of patients had persistent ALT elevations above 3X ULN (three times the upper limit of normal) during the treatment period. Persistent is defined as consecutive elevations at least one week apart. No patients had changes in laboratory tests indicative of clinically significant hepatic dysfunction, and there were no Hy's Law cases.

"There are patients, such as those with familial hypercholesterolemia, who are on maximally tolerated doses of currently available medications and still are very far from appropriate target goals," said James A. Underberg, M.D., of the New York University Center for Cardiovascular Disease Prevention. "For these high risk patients, there exists a tremendous need for additional lipid lowering therapies."

Phase 3 Study in Hypercholesterolemic Patients at High Risk of Developing Coronary Heart Disease

This double-blind, placebo-controlled trial included 158 patients with hypercholesterolemia (LDL-C ≥ 100 mg/dL) and at high risk of developing coronary heart disease (CHD) who were taking a maximally tolerated dose of a statin. Patients were randomized 2:1 to receive a 200 mg dose of mipomersen or placebo weekly for 26 weeks. This study was conducted at 43 sites in the United States and Canada. This was the first study of mipomersen designed to evaluate patients with diabetes. More than 50 percent of patients in the study had type 2 diabetes.

Patients treated with mipomersen had an average LDL-C at baseline of 123 mg/dL. At the end of the study, these patients had an average LDL-C level of 75 mg/dL, representing an average LDL-C reduction of 48 mg/dL (37 percent). Half of the mipomersen-treated patients achieved LDL-C levels of less than 70 mg/dL, a recognized treatment goal for high-risk patients. The reductions observed in the study were in addition to those achieved with the patients' existing maximally tolerated statin regimens. The trial also met each of its three secondary endpoints with statistically significant reductions in apo-B, non-HDL-cholesterol and total cholesterol. Study results are based on an intent-to-treat analysis (full analysis set). Detailed results will be submitted for presentation at a medical meeting.

Of the 105 patients treated with mipomersen, 60 completed treatment; of the 53 patients treated with placebo, 44 completed treatment. Twenty-six of the discontinuations in the mipomersen group were reported as being related to adverse events, the nature of which was generally similar to previous studies. Two of the discontinuations in the placebo group were reported as being related to adverse events. There was one death in the study due to acute myocardial infarction in a patient treated with placebo.

Elevations in ALTs in patients treated with mipomersen were observed that were generally similar in character with those seen in other studies. In this study, 10 percent of patients had persistent ALT elevations above 3X ULN during the treatment period. Persistent is defined as consecutive elevations at least one week apart. In many cases, these elevations were associated with increased hepatic fat content, as measured by MRI. No patients had changes in laboratory tests indicative of clinically significant hepatic dysfunction, and there were no Hy's Law cases.

"The completion of these phase 3 studies is a significant milestone for the mipomersen program, for antisense technology and for patients in need," said Isis Pharmaceuticals Chairman and CEO Stanley T. Crooke. "Mipomersen's lipid-lowering activity demonstrates the value antisense drugs can bring to patients. Our robust pipeline is evidence of the efficiency of our technology and the potential value we can create."

Late-Stage Development Plan

Genzyme's initial U.S. and E.U. regulatory filings for mipomersen will seek marketing approval for the treatment of patients with the genetic disease homozygous FH (hoFH). These initial filings may also include patients with severe hypercholesterolemia. In the first half of 2011, Genzyme expects to submit the initial U.S. and E.U. filings, and to have made progress toward filing in other major international markets.

As previously reported, the phase 3 study of mipomersen in hoFH patients met its primary endpoint with 25 percent LDL-C reduction, and results were presented at last year's American Heart Association meeting. Genzyme and Isis in February reported that the phase 3 study of mipomersen in heFH met its primary endpoint with a 28 percent LDL-C reduction, and data will be presented at the European Society of Cardiology meeting this month. In addition, studies are ongoing and planned to evaluate alternative dosing regimens.