Questor shares tip: BTG's Varisolve clears another hurdle In 2010, Questor tipped shares in Biocompatibles, which had developed "drug-eluting bead technology." These are beads that are implanted in the body to block blood supply to areas of disease, and can be used to deliver drugs to a specific organ or tissue. Unusually, this biotechnology company was profitable and paying a dividend. Since Questor advised readers to take up BTG's offer, the shares have put in an impressive run. This was topped by some positive news yesterday on Varisolve. The treatment led to "a significant improvement" in symptoms in a late-stage clinical study - the second such trial to show this. BTG is now seeking US regulatory approval to launch the product next year. It will be the first non-surgical treatment for varicose veins. No serious or unexpected side effects were reported across the two late-stage studies, in which 590 patients received treatment. All of this looks very promising. Indeed, last year BTG said that peak annual sales of the drug could hit $500m (£310m). Questor first recommended shares in Biocompatibles in September 2010 at 270p. Excluding the 10p cash element, 1.6733 BTG shares are now worth 631.2p, some 134pc above the initial tip price. The share price is now above the average price target of the City analysts that are monitored by Bloomberg, which stands at 368.8p. There is still potentially much more upside from Varisolve, so investors should hold on to the equity. However, investors who bought into Biocompatibles are now sitting on some impressive profits in a notoriously risky sector and should consider "top slicing" the investment. This is where you sell half of your holding to bank some profits, but keep hold of the rest of the shares. Officially, however, the rating is now hold.