New experimental drug called TAS-114 was found to increase the anti-cancer properties of chemotherapy drugs without increasing the side effects in cancer patients, finds a phase 1 clinical trial study presented at the 28th EORTC-NCI-AACR (1) Symposium on Molecular Targets and Cancer Therapeutics in Munich, Germany.
Dr Takekazu Aoyama, a surgeon and vice president of clinical development at Taiho Oncology Inc, Princeton, USA, described how TAS-114 in combination with another chemotherapy caused tumors to shrink in patients with advanced non-small cell lung cancer, pancreatic cancer, colorectal cancer and breast cancer. In addition, some patients whose cancer had failed to respond to other therapies were able to continue with the treatment and their disease remained stable without progressing for more than six months.
TAS-114 inhibits deoxyuridine triphosphatase (dUTPase) -- a 'gatekeeper' protein that acts on FdUTP, a metabolite of the anti-cancer drug 5-fluorouracil (5-FU), and restricts its incorporation into the DNA of cancer cells, thereby enabling the cells to continue living and proliferating. Research has already shown that tumors with high levels of dUTPase are resistant to 5-FU chemotherapy, and so successful inhibition of dUTPase may be an important step in enhancing the activity of 5-FU.
TAS-114 and S-1 were given orally twice a day for 14 days before food, followed by seven days rest before repeating. The doses ranged from a starting dose of 5 mg/m2 (TAS-114) and 25 mg/m2 (S-1) up to 240 mg/m2 and 36 mg/m2 respectively. The trial aimed to determine the maximum tolerated dose and the recommended dose, while also looking at how well the drugs worked against the tumors and how they interacted with the body (pharmacokinetics and pharmacodynamics). In addition to the cancers already mentioned, patients with cancers of the liver, biliary tract, endometrium and stomach were included.
The most recent data from the trial presented at the Symposium showed that 15 of the patients were able to continue receiving the treatment for more than six months without their disease progressing. In addition, tumor responses were observed in three of the patients with non-small cell lung cancer, one with pancreatic cancer, one with breast cancer and one with colorectal cancer.
Dr Aoyama said: "These results show favourable responses across all the tumor types and they were particularly outstanding in patients with non-small cell lung cancer where we saw robust partial tumor responses and good disease control rates. We consider that to be able to control disease for a period as long as six months and beyond provides a significant clinical benefit to patients who had all been previously heavily treated.
"In addition, we saw no additional toxic side effects in patients who were given the drug combination above what is expected with S-1 alone. Patients tolerated the treatment well and the side effects were manageable. These findings warrant further investigation of the drug combination in a phase II clinical trial."