Peter,
Pharmacopeia discusses competing technologies in their 1996 Form 10-K, page 12:
Libraries of small molecule compounds, which are preferred as drug candidates due to their increased potential for oral bioavailability and long duration of action, have recently been developed using competitive techniques. Two such techniques are based on the "pool and split" solid phase combinatorial chemistry approach used by the company. The first uses oligonucleotide or peptide tags on each bead to identify each synthesis step. These large molecule tags are relatively fragile, which limits the nature of reaction conditions (temperature, pressure, etc.) and reagents (acids, bases, etc.) that can be used to build compounds. In addition, these large molecule tags complicate the synthesis of compounds or beads. The Company's proprietary tags, in comparison, are durable, simple to attach and detach, and allow the Company to make larger and more diverse libraries of small compounds. The second "pool and split" combinatorial chemistry technique uses deconvolution to identify the chemical structure of compounds found active in assays. Deconvolution is a slow, labor-intensive process, and may require several weeks of scientists' time to determine the structure of a single active compound. The Company's tags permit hundreds of structures to be determined each day.
The first competitive technique appears to be the one on which the Affymax patent has been issued. From the abstract it appears that the Affymax patent covers oligomers, while the PCOP patent claims specify non-oligomeric compounds, although the use of multi-stage synthesis for more complex molecules is mentioned. If the Affymax claims are based specifically on DNA tags, PCOP may also argue that due to limitations imposed by the size and instability of their tags, the Affymax method does not enable the synthesis of all possible combinatorial compounds. The Affymax patent refers to identification only at the monomer level, so with respect to the small-molecule libraries of PCOP, the overlap may be small. On that basis, PCOP could then show that their synthesis is performed at a more primary "stage".
Will |
