* Human Genome Sciences Inc., of Rockville, Md., increased its ownership stake in Vascular Genetics Inc., of Research Triangle Park, N.C., from 19.9 percent to 33.9 percent. The increased shares resulted from a redistribution of the original holdings of the founding shareholders and a cashless exercise of warrants held by Human Genome Sciences, based on services rendered to Vascular Genetics. Human Genome Sciences disclosed it was taking part in the formation of the company a year ago. (See BioWorld Today, Nov. 11, 1997, p. 1.)

* 3-Dimensional Pharmaceuticals Inc., of Exton, Pa., said DuPont Co., of Wilmington, Del., licensed its DirectedDiversity technology to discover and refine compounds for a specific agrochemical target. DuPont will have an exclusive license to all active compounds identified during the collaboration. 3-Dimensional gets licensing fees as well as milestone payments and royalties on resulting products.

* Trega Biosciences Inc., of San Diego, entered into an agreement to acquire NaviCyte Inc., of Sparks, Nev., a private company focused on drug selection through in vitro screening and PK-Informatics tools. NaviCyte will operate as a wholly owned subsidiary of Trega and is expected to relocate operations to Trega's headquarters. The terms calle for NaviCyte to receive 2.5 million shares of Trega common stock, plus about $350,000 in cash. The transaction is expected to close before the end of the year.

* Vertex Pharmaceuticals Inc., of Cambridge, Mass., began a Phase II clinical trial with Incel (biricodar dicitrate) for the treatment of relapsed small-cell lung cancer. Incel is designed to restore or enhance tumor sensitivity to chemotherapeutic agents by blocking P-glycoprotein and multidrug resistance protein. The study is an open-label, multicenter trial to evaluate the tolerability, pharmacokinetics and antitumor activity of Incel in combination with doxorubicin and vincristine in patients with progressive disease who responded to initial therapy and then relapsed.

* Vical Inc., of San Diego, disclosed expanded efficacy and survival data from clinical trials with Allovectin-7, a potential cancer treatment, in patients with advanced, unresectable squamous-cell cancer of the head and neck. The company also said it began a larger, multicenter Phase II trial with the gene-therapy treatment in up to 60 patients with head and neck cancer.