New antibody drug helps cells kill blood cancer

By Ben Hirschler

LONDON (Reuters) - A new kind of antibody drug that makes the body's own "killer" cells fight tumors has produced promising early-stage results in patients with a deadly form of blood cancer, researchers said on Thursday.

All seven patients with previously incurable non-Hodgkin's lymphoma (NHL) who were given the highest dose of Micromet Inc's experimental drug blinatumomab showed either complete or partial responses.

The results, which were published in the journal Science, are a boost for the concept of harnessing the power of the body's cytotoxic, or cell-destroying, T-cells against tumors.

Until now, scientists have struggled to find a way of triggering a T-cell attack. But blinatumomab works by binding them to cancer cells, allowing the T-cells to more effectively kill the tumor.

Importantly, it does so without setting off uncontrolled T-cell activity. Two years ago six men were left seriously ill when a clinical trial of another experimental drug made by TeGenero went badly wrong.

"It's a very different kind of response," Patrick Baeuerle, Micromet's chief scientific officer, told Reuters. "It does activate the T-cells but it only activates those in contact with a tumor cell, so it is very conditional."

If all goes well, German-U.S. firm Micromet hopes next year to conduct a pivotal clinical trial necessary to win regulatory approval.

The drug, for which AstraZeneca has marketing rights in North America, is also in mid-stage Phase II clinical tests against acute lymphocytic leukemia.

In the Phase I trial reported for NHL, 38 patients were given varying doses of the drug, with 11 of those receiving higher dosages showing major responses and tumor regression, despite being given no other supporting chemotherapy.

There were a number of side effects with the product, which targets a protein called CD19, but most occurred in the first week of treatment and usually normalized.

Significantly, the amount of drug needed was much lower than for existing antibody treatments such as Roche and Genentech's Rituxan/MabThera.

"With these low doses, cost of goods should not be much of an issue," said Baeuerle.

(Editing by Paul Bolding)