Preliminary data from a Phase III trial of IDEC PharmaceuticalsCorp.'s monoclonal antibody against non-Hodgkin's B-celllymphoma showed at least partial tumor shrinkage in nearly 50percent of patients so far evaluated.

Officials of the San Diego company and clinical investigatorsdescribed the anti-tumor activity as encouraging and comparable toconventional chemotherapy with significantly less toxicity.

The antibody, called IDEC-C2B8, is being developed as a substitutefor chemotherapy and radiation. However, because it does not causethe same serious side effects as the conventional treatments, patientstaking IDEC-C2B8 also can receive chemotherapy.

Tumor reduction data from 48 of 166 patients enrolled in the open-label trial were released Tuesday at the American Society of ClinicalOncology (ASCO) annual conference in Philadelphia.

Investigators said the preliminary Phase III findings confirmedpositive results demonstrated in an earlier Phase II study in which 50percent of 34 patients treated experienced a complete or partialresponse to the antibody. Complete response is defined as 100percent tumor elimination and partial response is between 50 and 100percent shrinkage.

Full results, including the drug's ability to delay progression of thedisease, are expected to be available in December 1996. All 166patients finished treatment in March 1996.

Drug Approval Filing Next Year

IDEC earlier this month registered for a public offering of 1.5 millionshares to raise about $40 million. It anticipates filing for marketclearance of the lymphoma treatment with the FDA by mid-1997based on the agency's new guidelines for accelerated approval ofcancer drugs.

IDEC is developing the antibody in collaboration with GenentechInc., of South San Francisco _ which is 70 percent owned by RocheHolding Ltd., of Basel, Switzerland _ and Zenyaku Kogyo Co. Ltd.,of Tokyo.

IDEC's stock (NASDAQ:IDPH) closed Tuesday at $29.62, down 50cents. IDEC shares have jumped 8 percent since the companyregistered for its equity offering. (See BioWorld Today, May 7,1996, p. 1.)

When IDEC reported Phase II trial results in October 1994, thecompany's stock was trading at $2.94. Since then it has soared$26.68 in 19 months, a 900 percent increase. The Phase III trialbegan in April 1995.

Genentech (NYSE:GNE) ended Tuesday down 12 cents to $52.50.

IDEC's monoclonal antibody targets the CD20 antigen on the surfaceof B-cell lymphomas and mature B cells, stimulating a patient'simmune system to kill the malignant cells. Although normal mature Bcells also are destroyed, B-cell precursor cells are not affected,allowing the body to replenish its B cell supply.

Current treatments for non-Hodgkins B-cell lymphoma are off-labelchemotherapy and radiation, both of which have significant seriousside effects and must be administered over four to eight months.

IDEC's antibody is among the most advanced biological drugs indevelopment for non-Hodgkin's lymphoma.

IDEC-C2B8 is taken in four weekly infusions. Study results,including the Phase III preliminary findings, demonstrate themonoclonal antibody is well tolerated. Side effects in the Phase IItrial primarily were mild to moderate flu-like symptoms.

Safety data also have shown the antibody does not damage bonemarrow or produce other toxic effects of chemotherapy and radiation.

In the current Phase III trial, patients enrolled had relapsed low-gradenon-Hodgkin's lymphoma, which is the most severe form of thedisease and affects about 145,000 people in the U.S. Typicallypatients live an average of 6.6 years from diagnosis and experiencenumerous relapses.

The 166 patients in the pivotal study had received chemotherapy, butwere given only the monoclonal antibody during the trial, which isconducted at 30 medical centers.

Primary endpoints are achievement of at least partial responses in 35percent to 40 percent of the patients and a median time fromtreatment to progression of the disease of eight months.

In addition to the 50 percent response rate demonstrated in the PhaseII study, the 17 of 34 patients who experienced tumor shrinkage had amedian time to disease progression of 10.2 months.

Of the 48 patients evaluated in the Phase III trial, 23 (48 percent)experienced a response (6 with complete responses and 17 withpartial responses). Data for median time to disease progression wasnot yet available.

The trial's investigators said chemotherapy has produced 45 percentresponse rates and an average delay of disease progression of four toeight months.

In other ASCO presentations:

* Amgen Inc., of Thousand Oaks, Calif., and Genentech reportedtheir versions of thrombopoietin stimulated growth of platelets inearly clinical trials involving cancer patients undergoingchemotherapy. Amgen reported results of Phase I/II studies andGenentech released data from Phase I trials. The drugs are designedto restore platelets, which promote blood clotting, destroyed bychemotherapy and to reduce reliance on platelet transfusions. n

-- Charles Craig

(c) 1997 American Health Consultants. All rights reserved.