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Phase III Trial of Irinotecan and Gemcitabine Underway in Pancreatic Cancer

Phase III Trial of Irinotecan and Gemcitabine Underway in Pancreatic Cancer

TAMPA, Florida—Phase II studies have shown that the combination of
irinotecan (Camptosar) and gemcitabine (Gemzar) are well tolerated and active
in advanced or metastatic pancreatic cancer, and this combination is now being
tested in randomized phase II and phase III trials, said Caio Max S. Rocha
Lima, MD. Dr. Rocha Lima is assistant professor of medicine at the University
of South Florida’s H. Lee Moffitt Cancer Center in Tampa, Florida.

Dr. Rocha Lima said that two phase II trials have shown that irinotecan has
single-agent activity in pancreatic cancer. A trial conducted by the European
Organization for Research and Treatment of Cancer (EORTC) included 34 patients
who had advanced pancreatic cancer and no prior chemotherapy. They were treated
on the European schedule of irinotecan at 350 mg/m² given over 30 minutes every
3 weeks. Dr. Rocha Lima said that in 32 evaluable patients there were 3 partial
responses (PR, 9%) and 13 patients with stable disease (SD, 39%), for a
response rate of around 10%. Median survival was 5.2 months. "This is in
the same range as single-agent gemcitabine for pancreatic cancer," Dr.
Rocha Lima said.

Japanese researchers did a similar phase II trial in 61 patients with
advanced pancreatic cancer. Two regimens tested irinotecan 100 mg/m² weekly for
4 weeks on, 2 weeks off, or irinotecan 150 mg/m² every 2 weeks. Dr. Rocha Lima
said that in 35 patients evaluable for response there were 4 PRs (11.4%).

"Preclinical data suggest synergistic interactions for the combination
of irinotecan and gemcitabine," Dr. Rocha Lima said. "In the phase I
trial we had three previously untreated pancreatic cancer patients, and there
were partial responses in two of these patients. A third patient with
metastatic adenocarcinoma of unknown primary with distribution of disease below
the diaphragm and potentially another pancreatic cancer patient also had a
durable PR."

Dr. Rocha Lima’s group then pursued a phase II trial that has been
completed and submitted for publication. This trial included 45 patients with
previously untreated advanced and/or metastatic pancreatic cancer. The
treatment schema included gemcitabine 1,000 mg/m² over 30 minutes and
irinotecan 100 mg/m² over 90 minutes, both on days 1 and 8. The cycle repeated
every 21 days, as a 2 weeks on, 1 week off schedule. "Three fourths of the
population had metastatic disease. Only three patients had prior radiation
therapy and 5-FU," Dr. Rocha Lima said.

The combination produced 9 (20%) radiologically confirmed partial responses
(CI, 7%-29%). Twenty-five (66%) of the patients with elevated CA19-9 levels at
entry had a drop of at least 25%, and 31% had CA 19-9 decrease by more than
50%. Time to progression was 2.8 months, and 1-year survival was 27%.

Response rates were not affected by patient age, gender, extent of disease,
or number of involved organ sites. Only 6.7% of patients had grade 3 diarrhea,
and there was no grade 4 diarrhea. "The reason was probably the day 1 and
day 8, every 21-day cycle," Dr. Rocha Lima said. "There was little
nausea and vomiting (2.2% grade 3-4), and myelosuppression was
acceptable."

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