* Corixa Corp., of Seattle, said it signed a definitive agreement whereby it will acquire all outstanding shares of Anergen Inc., of Redwood City, Calif., in a stock-for-stock merger valued at $8.5 million. The acquisition is expected to close in January 1999.

* Diatide Inc., of Londonderry, N.H., said it withdrew its European marketing authorization application for AcuTect, a kit for preparing technetium 99m apcitide injection, after questions arose about reliability of contrast venography in evaluating efficacy. The product was approved by the FDA in September for imaging blood clots in lower extremities.

* ICN Pharmaceuticals Inc., of New York, said its licensing partner, Schering-Plough Corp., of Madison, N.J., was informed that the FDA approved Rebetron combination therapy for the treatment of chronic hepatitis C patients with compensated liver disease previously untreated with alpha interferon therapy. Rebetron includes Rebetol (ribavarin) capsules and Intron A (interferon alfa 2-b).

* Vysis Inc., of Downers Grove, Ill., said the FDA approved its PathVysion HER-2 DNA Probe Kit to detect and quantify the HER-2 gene in breast-cancer patients. Based on Vysis' Fluorescence In Situ Hybridization technology, the new test enables direct detection of both the HER-2 gene and the chromosome 17 on which the gene resides.

* Procept Inc., of Cambridge, Mass., and Pacific Pharmaceuticals Inc., of San Diego, signed a definitive merger agreement in a move first disclosed last month. The combined company will be called Procept and focus on anti-infectives and oncology. It has three products in the clinic. About 2.76 million Procept shares will be issued to Pacific shareholders.

* Quintiles Transnational Corp., of Research Triangle Park, N.C., and Hoechst Marion Roussel AG, of Frankfurt, Germany, have signed a letter of intent to negotiate an agreement under which Quintiles will acquire substantial assets of Hoechst's Kansas City-based Drug Innovation and Approval organization and open a Kansas City contract research facility. The agreement includes plans to employ about 540 current Hoechst employees based in Kansas City, and would guarantee Quintiles revenues of $436 million over five years for continued support and completion of Hoechst projects.

* Seattle Genetics Inc., of Bothell, Wash., began a Phase I trial using the single-chain immunotoxin SGN-10 in patients with carcinoma. Preclinical data suggested the fusion protein has activity against a variety of solid tumors.

* SuperGen Inc., of San Ramon, Calif., filed an abbreviated new drug application with the FDA for its Extra formulation of doxorubicin as a treatment for a variety of acute leukemias.

* TerraGen Diversity Inc., of Vancouver, British Columbia, and Schering-Plough Corp., of Madison, N.J., signed a collaboration to apply TerraGen's combinatorial biosynthesis capabilities to the discovery of anti-infective compounds. The deal was made between TerraGen and Schering-Plough Research Institute, of Kenilworth, N.J., the research and development arm of Schering-Plough. No terms were disclosed, although the agreement was said to include annual funding, milestone payments and royalties.

* Transkaryotic Therapies Inc., of Cambridge, Mass., began a Phase II trial of alpha-galactosidase A in patients with Fabry disease. The 24-patient trial is being conducted at the National Institutes of Health, and is expected to last about one year. The FDA has awarded the drug fast-track designation.