CAMBRIDGE, Mass. (TheStreet) -- A second experimental drug from Agios Pharmaceuticals (AGIO) designed to attack the "metabolism" of cancer cells has demonstrated early but strong clinical responses in a study involving patients with advanced leukemia.
Of 14 patients with acute myeloid leukemia (AML) evaluable for response, seven patients achieved an objective response to treatment with four escalating doses of the Agios drug known as AG-120. Four of the responding patients had complete remissions, meaning their bone marrow was clear of all cancer cells. Another two patients had near complete remissions. Responses to AG-120 are all ongoing with durations ranging from 15 days to five months.
"With the multiple complete remissions and early suggestion of durability, we're seeing a clear proof of concept with AG-120 and the potential to change the way [AML] is treated," said Agios CEO David Schenkein, in a phone interview from Barcelona where the AG-120 data are being presented at a cancer research meeting.
Based on these early results, Agios plans to enroll significantly more AML patients into the phase I study, all to be treated using the same dose of AG-120. This expanded study will start in the first of 2015. Agios is also testing AG-120 in patients with solid tumors, with results expected next year.
Agios fell 1.3% to close on Tuesday at $83.81, ahead of the announcement of the AG-120 study results. Agio's AG-120 is a pill designed to block a mutated, metabolic enzyme known as IDH1. Normally, cells use IDH1 to help break down nutrients and generate energy. When mutated, IDH1 alters the genetic programming of cells, preventing them from maturing and causing them to grow uncontrollably.
Patients with AML have bone marrow crowded with undifferentiated, rapidly dividing blast cells. AG-120 blocks the mutated IDH1 enzyme and allows the leukemic cells in the bone marrow to mature into normal blood cells.
Agio is developing a second drug known as AG-221 which works by blocking a related, mutated enzyme known as IDH2. An early study of AG-221 in AML patients has also yielded durable complete remissions. Agios estimates that between 18-24% of AML patients harbor either the IDH1 or IDH2 mutations.
The ongoing phase I study being presented tomorrow at the EORTC-NCI-AACR Symposium enrolled 17 patients with AML relapsed or no longer responding to currently approved treatments. Patients were treated in four cohorts with escalating doses of AG-120. Fourteen patients were evaluable for response; three patients were too early in their treatment schedules for analysis.
Of the 14 patients, four patients achieved a complete remission, two patients had a marrow complete remission and one patient had a partial remission. There was one complete remission at each dose level of AG-120, the two marrow complete remissions occurred were recorded at the third highest dose of AG-120, 500 mg once a day. All responding patients remain on AG-120.
The patient achieving a complete remission at the highest dose of AG-120 experienced a serious heart rhythm abnormality which improved by reducing the dose of the drug. This patient remains on a lower dose of AG-120.
Other side effects reported in the study include nausea, fatigue and shortness of breath. Six patients have died in the study to date, all related to their AML and not AG-120, investigators concluded.
In a previously reported deal, Celgene (CELG) licensed development and marketing rights to AG-120 outside the U.S., while Agios retains all U.S. rights to the drug.