JUNE 6 2009 13:28h
The phase II study involved patients aged 20 to 77 previously treated with standard chemotherapy for acute lymphoblastic leukemia, or ALL.
The phase II study involved patients aged 20 to 77 previously treated with standard chemotherapy for acute lymphoblastic leukemia, or ALL. It is a relatively rare cancer in which malignant immature white blood cells are overproduced and crowd out normal cells in the bone marrow. The disease can be fatal within weeks if left untreated.
The trial enrolled patients who had gone into remission after chemotherapy, but still had detectable levels of ALL cancer cells in their bone marrow.
Christian Itin, chief executive of Micromet, said elimination of the lingering cancer cells was the study goal because an estimated 61 percent to 94 percent of patients who have such detectable cells after chemotherapy typically relapse.
"The tumor builds up in the bone marrow and becomes visible in the blood and ultimately leads to death in a year or so for these patients," Itin said in an interview.
By contrast, the typical relapse rate for patients who have no detectable levels of tumor cells after traditional chemotherapy is only 0 to 6 percent, he said.
"These patients typically are considered cured," Itin said.
Patients in the trial were given several cycles of treatment with Micromet's drug, an antibody called blinatumomab that works by priming the immune system's killer T-cells to directly engage tumor cells.
Itin said 13 of 16 patients treated with blinatumomab and evaluated so far, or 81 percent, no longer have detectable tumor cells -- and the drug has therefore met its primary goal before completion of the study. The trial goal was for 22 percent of patients to achieve undetectable tumor levels, the CEO said.
The drug was well tolerated, with side effects seen mostly in the first 24 to 48 hours of treatment, researchers said, including fever and decrease in circulating white blood cells.
"These results are particularly important for these patients who are in a disease stage with extremely poor prognosis," said Dr. Ralf Bargou, the trial's lead investigator.
He said such patients currently have no treatment options, other than bone marrow transplants.
The results of the trial were presented in Berlin on Saturday at the Congress of the European Hematology Association.
Based on favorable results from the study, Itin said Micromet plans to begin a larger pivotal trial in the first half of 2010, which could evaluate the drug's response rate, response duration and time to relapse.
About 6,000 people in Europe and the United States are diagnosed every year with ALL, Itin said. They include an estimated 500 to 1,000 of the type evaluated in the study, meaning they have gone through multiple courses of chemotherapy and still have tumor cells left in the bone marrow.
The company has also seen encouraging results for the drug in trials against non-Hodgkin's lymphoma and Itin said the medicine could have big sales potential if larger trials against leukemia and lymphoma replicate trends seen to date.
"In ALL, we're looking at a peak (annual) sales potential of a few hundred million dollars," he said, with much bigger potential in the far-larger population of lymphoma patients.
Micromet is currently developing blinatumomab on its own. But Itin said the medicine's manufacturer, London-based AstraZeneca Plc, has an option to North American marketing rights if it is approved in the United States.
"If the option is exercised, we get a good double-digit royalty stream and significant payments at the exercise of the option," said Itin, who noted Micromet retains all rights outside of North America.