BioWorld International Correspondent
MUNICH, Germany - The U.S. FDA gave GPC Biotech AG written confirmation that it may start a Phase III registrational trial with its lead compound. The drug candidate, satraplatin, is a small-molecule platinum derivative, which will be tested on patients suffering from hormone-refractory prostate cancer (HRPC) who have failed prior treatment with chemotherapy.
The notification from the FDA is official culmination of the Martinsried, Germany, company's successful completion of both a special protocol assessment (SPA) and meetings with the FDA at the end of Phase II trials. The SPA program is a set of procedures, established in 2002, to encourage meaningful dialogue between the agency and drug developers before the beginning of a registrational trial. As part of the program, the FDA evaluates whether the protocol for a clinical trial is adequate to meet the scientific and regulatory requirements for FDA marketing approval.
GPC will model the trial on a smaller Phase III trial successfully conducted by the European Organization for Research and Treatment of Cancer, the results of which were presented at the American Society of Clinical Oncology annual meeting in June. The EORTC study followed patients who were treated with satraplatin plus prednisone, a standard synthetic hormone often used to treat advanced prostate cancer, and prednisone alone. Among 50 patients, the study found that the average time to disease progression was 5.2 months in those treated with satraplatin vs. 2.5 months in those without. The median overall survival time was 15 months for patients treated with satraplatin compared with 12 months for patients in the control arm.
"Moreover, after six months, 41 percent of those treated with satraplatin were progression-free, vs. 22 percent in the study's control arm," Bernd Seizinger, CEO of GPC, told BioWorld International. "With the small size of the trial, it's rewarding to have a statistically significant result. The most remarkable outcome is the doubling of the time" to progression.
The upcoming study will assess the safety and efficacy of satraplatin in combination with prednisone as a second-line chemotherapy regimen in patients with hormone-refractory prostate cancer. The primary endpoint will be time to disease progression.
"This approach will help us qualify for expedited approval," Martin Braendle, a spokesman for GPC, told BioWorld International. "Otherwise, taking patient survival as the endpoint would add on two years to the process." The study's objectives also will include evaluation of pain control and survival, as well as an assessment of drug safety in this particular patient population.
"At present, we expect to be able to file an NDA in 2006," Braendle said. "We also expect to find a partner for the drug in the next 12 to 24 months, which may also mean significant cash inflow for the company at that point." He declined to name specific potential partners or give concrete financial details.
Patients with HRPC have a fairly advanced form of prostate cancer, which is one of the most common cancers in the United States and Europe. At present, early stage prostate cancer typically is treated by radiotherapy or surgery, both of which have significant risks. Further treatment is usually synthetic hormones. "Most patients initially respond very well," said Seizinger, "but the vast majority eventually develop a hormone-resistant form of cancer." He added that prostate cancer is presently not often treated with chemotherapy, although that approach is becoming more common. "The situation is a little like breast cancer 10 years ago."
One advantage that satraplatin would have over existing treatments is that it is designed to be administered orally. That raises the possibility that it could be an outpatient treatment, reducing hospital time for patients with HRPC. Braendle said that this characteristic means the compound could actually benefit from pending changes to the German health care system, because cutting back on hospital stays would be an important part of overall cost-reduction measures.
Prostate cancer is the most common cancer among men in the United States. More than 220,000 new cases are projected for 2003, and an estimated one in six men is expected to develop prostate cancer in his lifetime. An estimated 100,000 patients in North America, Europe and Japan combined have hormone-refractory prostate cancer. For those patients failing hormone therapy, treatment currently involves a limited number of options, including chemotherapy. Those options are usually only marginally effective. For those patients who fail first-line chemotherapy, there are currently no approved treatment regimens.
Shares in GPC have soared on the news, rising more than 20 percent over two days, to close Tuesday at €7.96 on the Frankfurt exchange.