LONDON ¿ Xenova Group plc, of Slough, said XR9576, for the prevention of drug resistance in cancer chemotherapy, has entered Phase II clinical trials.

The company, which specializes in the development of small-molecule drugs derived from microorganisms, also announced changes to the scientific advisory board to reflect the intention to focus on oncology, following the disposal of Xenova Discovery to Terragen Diversity Inc. in March.

Despite the commencement of the clinical trials, operating expenses for the first quarter ended March 31, 1999, fell to #3.97 million (US$6.4 million), compared to #4.7 million for the same quarter of 1998. Xenova said this was due to cost cutting at the end of 1998. Revenues for the quarter fell to #950,000 ($1.5 million), compared to #1.9 million in 1998. The profit for the three months was #115,000, up from a loss of #2.7 million, due to the disposal of the Discovery division.

Phase I results for XR9576, a P-glycoprotein inhibitor, were presented to the annual meeting of the American Society of Clinical Oncology last week, showing that XR9576 administered by either oral or intravenous route was well tolerated at all doses, and completely inhibited P-glycoprotein. The Phase IIa program, now in progress in centers in the U.S. in conjunction with the National Cancer Institute, and in the U.K., is studying the effect of intravenously administered XR9576 in combination with a variety of existing and approved cytotoxic drugs, such as doxorubicin, paclitaxel and vincristine. The trials are expected to be completed by the end of 1999.

The P-glycoprotein mechanism, by which drugs are pumped out of tumor cells, is believed to be responsible for between 30 percent and 90 percent of cases of chemotherapy failure due to multi-drug resistance. Xenova estimated it may affect 1 million new U.S. patients a year. n