S-1 and Platinol Combo Shows Promise Against Cervical Cancer, Phase 3 Trial Indicates

Adding S-1 to Platinol (cisplatin) chemotherapy improved cervical cancer patients’ response to treatment and lengthened the time it took for their disease to progress, according to a Phase 3 clinical trial.

Taiho Pharmaceutical, which developed S-1, presented the results at the American Society of Clinical Oncology annual meeting in Chicago, June 2-6. The poster-session presentation was titled “A randomized phase III trial of cisplatin with or without S-1 in patients with FIGO IVB, recurrent, or persistent cervical cancer: An Asian study.”

S-1, also known as TS-1, is an oral fluoropyrimidine with a similar mechanism of action as the chemotherapy 5-FU. Taiho designed it to have improved anti-tumor activity, however.

The company said S-1 has shown punch against gastric, colorectal, breast and pancreatic cancers. A Phase 2 trial whose results were published in the Annals of Oncology reported that S-1 displayed anti-cancer activity in cervical cancer as well.

Taiho’s Phase 3 clinical trial (NCT00770874) covered 375 patients with recurrent or persistent advanced cervical cancer. Participants were randomized to receive either a combination of S-1 and Platinol, or Platinol only. The combo group received oral S-1 and Platinol daily for 14 days, followed by a seven-day break. The other group received only Platinol for the 14 days.

The trail failed to achieve its primary goal of the combo therapy significantly increasing patients’ overall survival. Those who received S-1 had a median survival of 21.9 months, compared with 19.5 months for the Plationol-only group. The 2.4-month difference was not statistically significant.

Although the combo failed to meet the trial’s primary goal, it achieved its secondary endpoints.

Forty-four percent of the S-1 group showed either a full or partial response to the combo, versus 20 percent of the Platinol-only group. Combo users had a significantly longer progression-free survival rate, or the time it takes for a disease to progress or a patient to die: 7.3 months, compared with  4.9 months in the Platinol-only group.

Although the combo was well tolerated, those who took it had a higher number of severe adverse events than the Platinol-only group. The most common side effects were low levels of immune cells called neutrophils, low levels of white blood cells, and anemia.