Bavarian gives cancer vaccines another booster jab

Another day, another set of trial results from a prostate cancer vaccine. But unfortunately for Bavarian Nordic, the market was not quite as enthusiastic about the fact that its newly acquired drug ProstVac demonstrated significantly longer survival times for the 125 patients taking it.

Notwithstanding patients on ProstVac reporting median overall survival of 8.5 months, compared with just 2 months for patients taking the current standard of care, shares in the group only rose 5% to DKr119. While this was no mean feat in the panicky European markets, it was nowhere near the 33% achieved yesterday by Dendreon on less impressive data.

By way of explanation, the more muted share price reaction could sensibly be ascribed to the fact that Provenge is more advanced and is in phase III trials. But that is the point where the logic stops. The massive rise in Dendreon's shares looks heavily over done, given that while the interim results showed that Provenge cut the risk of death by 20%, the drug will have to get that percentage up to 22% in the final analysis next year if it is to avoid clinical failure.

Bright side too bright?

Whether the drug will be able to do that is debatable (Dendreon rise looks overdone, October 6, 2008), and many analysts have cautioned about counting chickens too early. At the moment the market appears to be ignoring that advice and building an extension to the hen house. This optimism seems misplaced given the appalling track record cancer vaccines have in successfully completing phase III trials.

The numerous bodies littering the path to marketing have included Favrille’s SpecifId, and Genitope’s Myvax, both of which failed to show statistical clinical benefits. In July, Oxford BioMedica reported disappointing results for its TroVax trial in renal cancer and the most recent set back in the sector has affected Cell Genesys and Takeda, who halted trials of prostate cancer vaccine, GVAX, after a high number of deaths in the treatment arm of their phase III Vital-2 test.

Cell Genesys is now busily examining the data from the trial in an attempt to determine the cause of the disproportionate deaths, which they are hoping will be down to imbalances between the two treatment arms, rather than the vaccine itself. But while this analysis is going on, the future of the drug remains uncertain.

Illustrating just how difficult the therapy area is and the challenge facing ProstVac, the table below shows that despite some estimating that the prostate cancer market could be worth up to $5bn, prostate cancer vaccines are only forecast to achieve sales of $483m by 2014, and if GVAX’s contribution is taken out this the figure falls to $323m.

What is also telling is that many analysts have not ascribed any value to the earlier stage products, with the exception of Pfizer’s CDX-110.

However, alongside the ProstVac results today there was some other good news in the sector. Oxford BioMedica reported that the FDA had agreed to review data from the TroVax trials in renal cancer, albeit with a view to approval in a very small sub population. However, the 10% rise in the shares to 6¾p was caused by licensing partner Sanofi-Aventis announcing that it would continue development of the drug in larger colorectal trials.

But as these pieces of good news are far and few between, Bavarian Nordic investors should for now celebrate the success of the drug, which could help the company’s over reliance on unpredictable government bio-defence contracts (Bavarian Nordic struggling to inject confidence - September 8, 2008), whilst remembering there are still many hurdles to long-term success.