Stocks of Serono, Europe’s largest biotechnology firm, were down 4.8 percent by midmorning Wednesday after it was announced that it had been forced to stop late-stage trials on two of its drugs in development.

The trials were stopped upon recommendation of two separate data and safety boards.

Trials for the cancer drug Canvaxin in its function as a treatment for Stage IV melanoma were halted when data revealed that the drug had no greater effect on the cancer than did a placebo.

Trials, however, will continue for Canvaxin in the treatment of Stage III melanoma, an earlier stage of the skin cancer.

In a more serious development, Phase 3 trials of the drug onercept in the treatment of psoriasis were forced to be halted last year when two patients were diagnosed with sepsis and one of the patients subsequently died.

Sepsis is a recognized side-effect of the treatment of psoriasis with drugs, but in this case the risks were determined not to outweigh the possible benefits of treatment with the drug.

While these halted trials were a definite setback for Serono, analysts believe that the news sounds worse than it is and declined to revise profit estimates for the company.

The reasons cited for this include the sales numbers for another of Serono’s psoriasis drugs, the fact that trials of Canvaxin are ongoing in the treatment of Stage III melanoma, and the increased market for Serono’s Multiple Sclerosis drug, Rebif, in the wake of another company’s forced withdrawal of its MS drug from the market in February.