LONDON ¿ Antisoma plc is to move Therex, an antibody treatment for cancer into Phase IIa, following completion of Phase I studies by the cancer charity, the Imperial Cancer Research Fund (ICRF). Therex, a humanized antibody (huHMFG1), targets most common epithelial cancers, including breast, lung, ovarian, gastric and colorectal cancer, stimulating the body¿s immune system to kill cancer cells. Preclinical studies in a mouse model demonstrated improved survival for Therex-treated mice.

Glyn Edwards, CEO, told BioWorld International, ¿We licensed this as part of a bundle at the same time as our lead compound, Theragyn. The ICRF had already progressed it to Phase I, but we were not happy that the preclinical package was good enough from a commercial point of view. For this reason we have not talked about it before because that would have implied it was further down the track than is the case.¿

Antisoma, based in London, has paid the ICRF to fill in the missing aspects of the preclinical file over the past two years. Meanwhile, the Phase I study of 18 patients with primary breast cancer conducted by ICRF at Guy¿s Hospital, London, showed the drug is well-tolerated at repeat doses.

¿The Phase I data is now complete. The ICRF may carry on recruiting more patients, but we don¿t need more to progress to Phase II,¿ Edwards said . There is no indication of efficacy from the Phase I because all patients had primary breast cancer in which existing treatments are usually effective.

Antisoma now is working out a strategy for Phase IIa, which will be in breast cancer patients with metastatic disease suffering a first relapse. However, the trial is unlikely to start before the first half of 2001 because the company wants to set up large-scale manufacturing of the antibody, rather than rely on the small-scale production system at the ICRF. ¿Going to full scale-up now means it will take longer to start the trial, but if successful, it will mean we can get to market faster,¿ said Edwards.

Antisoma¿s lead product, Theragyn, an antibody-directed radioisotope, is in Phase III in ovarian cancer, and Phase II in gastric cancer. Partnered to Abbott Laboratories, of Abbott Park, Ill., the drug has FDA orphan drug status in ovarian cancer.