Agios slips on mixed solid tumor data for its Celgene-partnered cancer drug

One of Agios Pharmaceuticals' ($AGIO) blood cancer treatments demonstrated promise in a Phase I study against solid tumors, but the results fell short of some investors' expectations, sending the company's share value down about 10%.

In the study, Agios pitted its AG-120 against a handful of tumor types in 62 patients, testing whether the therapy could duplicate its previously established promise in hematologic malignancies. On the whole, AG-120 demonstrated itself safe and well tolerated, Agios said, shrinking one patient's tumors and stabilizing tumor growth for about half of the volunteers.

However, picking apart the results, Leerink analyst Seamus Fernandez noted the results from the 20 glioma patients were less than impressive. Half of those patients had their disease stabilized, but only four stayed that way after 6 months, Agios said, marking a response rate of just 25%. Comparatively, AG-120 charted a 56% rate in participants with the cartilage cancer chondrosarcoma and 43% in those with a liver cancer called intrahepatic cholangiocarcinoma, or IHCC. That spells an uncertain future for the drug in brain cancer, Fernandez wrote.

But Agios found the results encouraging enough to move forward with AG-120 in solid tumors, planning to enroll another 100 patients in expansion cohorts of its Phase I trial and blueprinting a Phase II study in IHCC to begin next year.

AG-120, like all of Agios' cancer candidates, is designed to starve malignant cells by targeting the enzymes they need to metabolize nutrients. The oral drug targets the enzyme IDH1, which, when mutated, promotes cancerous growth. AG-120 has demonstrated impressive results in acute myeloid leukemia (AML), and Agios is planning to launch a Phase III trial in that indication in 2016. Celgene ($CELG), the company's frequent partner, has licensed the ex-U.S. rights to AG-120 in a deal worth up to $120 million plus royalties.

Agios and Celgene are working through a Phase III AML study with top prospect AG-221, which has racked up remissions in tough-to-treat blood cancers across a handful of trials. The pair is also developing the early-stage AG-881, which inhibits both IDH1 and 2 and could eventually best its predecessors.

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