Monotherapy with the investigational agent RAD001 (proposed brand name AfinitorR) stops tumor growth in more than half of patients with advanced gastric cancer who have failed at least one earlier treatment, researchers announced here at the American Society of Clinical Oncology’s 2009 Gastrointestinal Cancers Symposium.

RAD001 is a once-daily oral inhibitor of mammalian target of rapamycin (mTOR), a key protein kinase regulating cell proliferation and angiogenesis.

Atsushi Ohtsu, MD, with the National Cancer Center Hospital East in Chiba, Japan, reported results in 53 patients with inoperable, recurrent or metastatic gastric cancer whose disease had progressed despite prior treatment and who were subsequently treated with RAD001, 10 mg/d, as part of a phase II trial.

All participants in the study were of Asian descent.

The primary efficacy endpoint was disease control rate (DCR), defined as complete response, partial response, or stable disease lasting at least eight weeks, according to RECIST criteria.

The median duration of therapy was 57 days, and nine patients remain on treatment.

Results showed a DCR of 55 percent at eight weeks, Dr. Ohtsu said.

Twenty nine (55%) of 53 evaluable patients had stable disease, 22 (41%) had progressive disease, and 2 (4%) had an unknown response. The objective response rate (ORR) was zero.

The median progression-free survival was 83 days, and nearly a third of patients were estimated to remain progression-free at four months. The median overall survival had not been reached at the time the data were analyzed.

The main adverse events were stomatitis, anorexia, fatigue, rash, peripheral edema, thrombocytopenia, diarrhea, pneumonitis, and hyperglycemia. The main grade ¾ adverse events thought to be related to RAD001 were stomatitis and hyponatremia, each occurring in three patients. Overall, the safety data observed in this trial were consistent with the known safety profile of RAD001.

Dr. Ohtsu said that he is encouraged by the results and added that treatment options for patients with advanced gastric cancer have been limited.

A spokesman for Novartis, which developed RAD001, said that a global phase III clinical trial program to test the efficacy and safety of RAD001 monotherapy in advanced gastric cancer will start recruitment this year. The target enrollment for the program is 500 patients.

Gastric cancer is the second most common cause of cancer-related deaths worldwide. The disease is highly prevalent among people of Asian descent, with more than half of new cases occurring in East Asian countries.

Written by Jill Stein
Jill Stein is a Paris-based freelance medical writer.
jillstein03(at)gmail.com