Fusion Antibodies PLC (AIM:FAB) tumbled by a quarter as it said an expected upturn in investment in new drug discovery and development programmes had not occurred.
Trading conditions remain very challenging, it added, with the result that revenue this half is behind current market expectations, at not less than £541,000.
Delays to contracts will also push some revenue into the second half of the year.
Even with the slower sales, Fusion Antibodies said that cost controls had kept its cash runway unchanged.
Shares were down 1.2p at 3.9p.