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CHINESE GENE THERAPY:
Gendicine's Efficacy: Hard to Translate
Clinical data supporting China's advances in gene therapy often appear in Chinese-language journals--which are inaccessible to many Western readers. To bridge the gap, James Wilson, editor of Human Gene Therapy (HGT), last year solicited a review in English summing up published clinical evidence behind China's first gene-therapy product, Gendicine, by Peng Zhaohui, CEO of SiBiono GeneTech in Shenzhen, the company that put Gendicine on the market.
Peng's review in the September 2005 issue of HGT has been cited at least a dozen times by experts as a definitive view of Chinese clinical trial results. However, Marshall Posner, medical director of the Head and Neck Oncology Program at the Dana-Farber Cancer Institute in Boston, says that, after reading translations of the original reports, the findings are hard to evaluate. The trials "were not done with a high degree of structure, and it is not clear what protocols were followed or how patients were randomized," Posner says. Others question the quality of the data.
Comparing Peng's summary with original Chinese-language reports, Science found that the summary did not include some information in the originals. For example, Peng described patients in a phase I (safety) clinical trial of Gendicine as having "advanced" cancers. But a Chinese-language report said seven of the 12 participants in this trial had limited primary tumors that had not spread to lymph nodes. Although the original paper reported that all 12 patients received surgery along with gene therapy, Peng's summary of therapeutic effects mentioned only treatment with Gendicine, noting that 11 patients who received it had a remission of cancer lasting more than 3 years. In a telephone interview, Peng said that he had inadvertently omitted data on the surgeries.
Peng's review discussed so-called phase II/III trials of Gendicine in 2001-2002, citing three primary publications. But the primary papers reported only phase II trials--relatively modest ones that had enrolled a total of 124 patients. (Phase III trials are larger and demonstrate efficacy.) Another flaw, says Anthony Chan, chair and chief of service of the Department of Clinical Oncology at Prince of Wales Hospital in Hong Kong, is that these trials--which compared Gendicine plus radiotherapy to radiotherapy alone for head and neck cancer--is that "the definition of complete response … was not provided," even though it is especially difficult to define in such cases.
China's State Food and Drug Administration (SFDA) approved Gendicine for production in 2004 without data from a standard phase III trial. Peng's explanation: SFDA did not require such trials for new drug approvals before May 1999, and because "our clinical trials were approved before 1999, we were not required to do phase III trials." Peng adds that this is "okay" because "the SFDA approved our drug on safety and efficacy."
(With reporting by Jerry Guo.)
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