Re: Patents and drug delivery systems
You are focusing in on the essential value of Depotech. Yes, depofoam can extend the patent protection of many drugs. But the nature of the product really leads to novel uses where a time-released, localized therapy is needed. Hence, it will not really even compete with generic imitations of products whose patents have expired. Rather, it will more often address new problems in therapeutics.
Liposomes were discovered by Dr. Alec Bangham (U.K.) in 1961. Phospholipids have a water-soluble "polar" phosphate end and a water-insoluble fatty acid tail. If dispersed in water, they will spontaneously form microscopic closed spheres with a water-phosphate center and the lipid part of the molecules pointing outward. Another layer of water-insoluble fatty acids (which were attracted to the first lipid layer) spontaneously coalesces around the outward-pointing lipids, and then the water-soluble polar half of the second layer is on the outside, happy to be swimming with polar water molecules.
There are three classes of liposomes: 1) unilammellar--which I so awkwardly just described above, 2) Multilamellar--as above, but multiple layers of membranes--like an onion, and 3) multivesicular liposomes--of which depofoam is a member. But depofoam is misnamed because it really has a honeycomb structure, rather than a bunch of spheres side by side. In order to have a honeycomb structure, lipids must be forced to form corners, which normally is impossible. The ability to overcome the corner/angle problem and reproducibly produce reliable drug delivery systems is the basis of DepoTech's proprietary technology platform.
Most liposomes are intended for intravenous use and are rather small--often less than 0.2 microns, and, at most 5 microns. Depofoam particles are typically much larger than 10 microns. The large size and high encapsulation volume are valuable features of an ideal drug delivery system. Virtually any water-soluble drug can be placed into depofoam. If a mass of depofoam is placed in a body cavity, the outermost lipid membranes eventually degenerate or are actively broken down by the host, releasing a small amount of drug, and exposing new lipid membranes for degeneration. Unencapsulated drugs are usually cleared from the host or patient in minutes to hours. Depofoam takes weeks.
Depotech is all about a promising unique patented drug delivery platform which enhances the therapeutic index of medications. You are right that, in this perspective, it is much more than an oncology company. So why the fuss over DepoCyt?
It will be the first FDA approved use of depofoam, hence it...
1) is the ultimate validation of the technology, increasing credibility
2) provides a revenue stream which enhances DEPO's fiscal integrity, and thus betters DEPO's bargaining position for future uses of the technology platform
3) and just happens to double the survival time for people with neoplastic meningitis--meaning that the stingiest, greediest, slimiest HMO's and insurance companies are going to have to pay for DepoCyt. (As a primary care internist I particularly enjoy #3).
Best Regards,
Tom D |
