Merrimack Pharmaceuticals has stopped a phase 2 lung cancer trial after an interim review showed it was destined to fail. The setback, Merrimack’s second flop in four months, wiped 35% off the company’s stock and left the rebooted strategy it implemented last year in tatters.
MM-121, the drug in the latest failed trial, is one of three prospects Merrimack put its faith in when it sold its approved product and commercial infrastructure to Ipsen last year. The idea was to refocus as a clinical-phase biotech and use some of the cash from the Ipsen deal to get the drugs to clinical trial readouts. Merrimack has executed that strategy. The problem is two of the drugs didn’t work.
Investigators enrolled 109 non-small cell lung cancer patients in the phase 2 and randomized them to receive anti-HER3 antibody MM-121 and docetaxel or the old chemotherapy alone. A review of data on the first 67 patients whose disease progressed found no benefit to adding MM-121 to docetaxel.
Merrimack responded to the news by terminating the trial and initiating a review of its pipeline. The review will look at the implications of the failed study for another midphase trial of MM-121, which is assessing the antibody in combination with fulvestrant in breast cancer patients. Both trials limited enrollment to patients with heregulin-positive cancer cells.
The breast cancer trial, which got underway in February, could continue, but the lung cancer readout has significantly dampened expectations. Shares in Merrimack traded down 35% premarket.
If Merrimack kills off MM-121, it will have lost two of the three drugs it tied its future to last year. The third, MM-310, is being tested in a phase 1 solid tumor trial that is due to deliver data later this year.
MM-310, an EphA2-targeted docetaxel formulation, is a different type of drug than MM-121 or the now-abandoned MM-141. But the MM-310 side of the pipeline has had its share of setbacks, too. MM-302, an HER-2-targeted doxorubicin formulation, failed an interim phase 2 data review late in 2016 and was jettisoned from the pipeline.