While we are all waiting for the approval of Provenge, it is worth noting that a research group at the University of Iowa has developed a very different type of prostate cancer treatment based on older technology.
Lubaroff et al. have just reported the results of a Phase I clinical trial of an adenovirus-based PSA vaccine in 32 men with metastatic, hormone-refractory disease. Each patient received a single, subcutaneous vaccine injection at one of three different dose levels, with the following outcomes:
- The vaccine appears to have been safe at all dose levels.
- There were no serious vaccine-related adverse events; the most common side effects were local skin reactions and cold/flu-like symptoms.
- 34 percent of patients produced anti-PSA antibodies.
- 68 percent of patients produced anti-PSA T-cell responses.
- PSA doubling times were increased in 48 percent of the patients
- 55 percent of patients survived longer than predicted by the Halabi nomogram.
The authors conclude that, “Although the … data are only derived from a small number of patients in this phase I trial, they are encouraging enough to pursue further studies.”
An article in U.S. News and World Report points out that this type of prostate cancer “vaccine” is based on technology that is very different from the technology used in the production of Provenge. At least in theory, this type of adenovirus-based therapy can be manufactured using methods similar to those used to produce vaccines like the so-called “swine flu” vaccine or the regular annual influenza vaccines. Furthermore, the fact that it can be given as a single injection has all sorts of implications for when it could be given to men, even with very early stage disease.
So far, this vaccine has been developed without commercial involvement of any of the large drug companies, but if it is to come to market there will need to be large-scale clinical trials, and that will start to raise questions about whether anyone can actually make money by commercializing a product of this type. Vaccines like the “swine flu” vaccines are developed with considerable government support. They would not be commercially viable without such support.
Filed under: Drugs in development Tagged: | adenovirus, PSA, vaccine
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Pretty interesting stuff to test vaccines on already dying patients. Looks promising to extend life.
We did a report on an adenovirus-based HIV vaccine tested in healthy people and it ended up giving them HIV.
Provenge sounds much more promising.
There is a huge difference between the use of “immunobiologic agents” such as Provenge to treat a patient who has a pre-existing condition and the use of true “vaccines” to prevent development of a clinical condition in a healthy individual.
Development of true vaccines for prevention of any clinical disorder does and certainly should come with a much higher need to prove that there is minimal risk (and preferably no risk at all) for any adverse impact on the health of the individuals being vaccinated.
By contrast, the use of immunotherapeutic agents to treat a specific disorder can take account of the inherent risks already facing the patient because s/he has a clinical condition that comes with definable outcomes if s/he receives no further treatment.