Therapy Analysis - Telomerase as a potential therapeutic target
The future
The early-stage status of the majority of these programmes
does not bode well for a telomerase therapy reaching the
market any time soon; this coupled with the 'background'
failure rate of 34% for all cancer therapies at Phase III means
that the future of Pharmexa's GV-1001 is not yet completely
assured, especially with the recent PrimoVax termination.
Graph 3 clearly illustrates how anticancer therapeutics tend to
stall in Phase III clinical trials, compared to the rapid progress
in enrolling new drugs into Phases I and II. The apparent
difficulty in progressing from Phase II to III is also
highlighted, as 67% of anticancers fail to demonstrate efficacy
at this critical stage. In addition, regardless of the huge
potential market available to an effective cancer therapy,
companies are still discouraged from developing agents due to
the controversy over the effectiveness of targeting telomerase
as a therapeutic target.
Another reason for companies being discouraged from investing in development programmes comes from patent issues. Geron holds a broad intellectual property portfolio on telomerase over many countries, including the gene itself, immunogenic telomerase peptides and scientific methods involving telomerase, including its detection and elements of the TRAP assay. Many developers fear moving into the field due to the potentially very expensive litigation which may ensue. This can be seen in recent legal battles being fought between Pharmexa and Geron over GV-1001. Thus far, Pharmexa has managed to retain rights to the intellectual property utilized in GV-1001 against fierce opposition, but failed in an attempt to obtain claims that would read on Geron's telomerase cancer vaccine, GRNVAC1.
As exciting as the therapeutic strategy appears, we can see that telomerase-based therapeutics have a long way to go before they may come into widespread clinical use. Specialist companies such as Geron and Pharmexa are however clearly making good progress in potentially exploiting the properties of telomerase, and so long as legal bureaucracy and scientific uncertainty are resolved in a fair and timely manner, one of these companies discussed could be on the verge of a veritable breakthrough; of which both the profitability and lifesaving potential could be highly significant.
Peter Ruscoe
