Business Notes BIOTECHNOLOGY

If at first you don't succeed, go back to the laboratory. That is what Genentech (1986 revenues: $134 million) must do now that the Food and Drug Administration has at least temporarily rejected t-PA, the company's revolutionary new, genetically engineered drug that dissolves blood clots, which often lead to heart attacks. The FDA asked South San Francisco-based Genentech to come up with further test data in support of the company's claim that the drug can increase the survival rate of heart-attack victims.

The decision was a shocker on Wall Street, where biotechnology stocks had been big winners. After the FDA ruling, the price of Genentech's shares plunged 11 1/2 points in one day, to 36 3/4. By the end of last week the price stood at 37 3/4. A domino effect also knocked down the stocks of rival biotech firms, some of which are developing drugs similar to t-PA. Such futuristic- sounding companies as Amgen, Biogen, Centocor, Cetus and Chiron saw their shares drop anywhere from 7% to 11% before recovering some of those losses.

The young industry's setback is likely to be short lived, however. Genentech is expected to win FDA authorization for t-PA, perhaps within a year or so. Says Robert Kupor, an industry analyst with the Seattle-based Cable, Howse & Ragen brokerage firm: "It's great stuff, and there's no doubt it will ultimately be approved." Once that happens, experts expect to see a $1 billion-a-year market for clot-dissolving drugs.