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Biotech / Medical : AVXT RESEARCH THREAD -- Ignore unavailable to you. Want to Upgrade?

To: chirodoc who wrote (22)	1/20/2000 10:43:00 PM
From: chirodoc	Respond to of 35

NEW VISTAS IN CANCER TREATMENT Modern vaccines specifically designed to treat cancer have been in development for well over a decade. Most of the early experimental procedures were conducted on very small numbers of patients, with doctors learning their craft one patient at a time. Another factor that prolonged the development of cancer vaccines was the inherently long nature of proving a successful outcome: when does it become significant that a patient is still alive? But by the mid-nineties the long labors of many dedicated researchers had begun to bear fruit, and viable product candidates moved into larger clinical trials. Cancer vaccines can be divided into two general classes. Some use cells or material from cells that have been removed from a patient, modified to be much more immunogenic, and then injected along with an adjuvant. These are typically referred to as ?autologous cell? vaccines. Other cancer vaccines contain immunogens that are antigens (derived from either chemical synthesis or recombinant DNA engineering) known to be present on whatever tumor type is being treated. Both of these approaches have their proponents. Fans of ?synthetic? vaccines point to the advantage of not requiring a patient to undergo surgery or biopsy to obtain vaccine material. Theoretically they could be used at the first hint of disease (or even before that). Synthetic vaccines can be standardized and manufactured in large amounts and at lower cost rather than be manufactured individually on site for each patient. Backers of the autologous cell vaccines point out that each patient?s tumor presents its own unique set of antigens, so their method guarantees that the patients will receive a vaccine presenting all the antigens that characterize their own genetically distinct tumors. We think the clinical results so far have demonstrated the value of both methods, and that each will find a role as immunotherapy emerges as part of the new oncology paradigm. There are currently over a dozen cancer vaccine product candidates in advanced development. Melacine, from Corixa Corp. (CRXA, $30), is a standardized mixture of lysed melanoma cell lines combined with an immunogenic adjuvant. Melacine recently obtained regulatory approval in Canada, and results from two Phase III trials against malignant melanoma are due very soon. An autologous cell malignant melanoma treatment from AVAX Technologies (AVXT, $9), known as MVAX, is now being commercialized in Australia and two European countries and is just beginning a pivotal trial in the United States. Other cancer vaccines under development include inactivated and genetically modified cancer cells (from Cell Genesys (CEGE, $16)); antibodies designed to mimic cancer antigens and elicit an anticancer antibody response (from Titan Pharmaceuticals (TTP, $18)); large immunogenic molecules carrying high concentrations of specific cancer associated antigens (from Progenics (PGNX, $62) and Biomira(BIOM, $8)); and DNA vaccines injected directly into tumors (from Vical (VICL, $37)). Several of these products are in late stage trials and could be available to US oncologists within a two to four year period. Given the lack of toxicity and minimal side effects seen with many of these vaccines so far, we think it likely that doctors will incorporate these products and the new hope they bring to cancer sufferers into their practices relatively quickly. Next week we will begin a more detailed discussion of these and other companies and their efforts to develop therapeutic cancer vaccines.

To: chirodoc who wrote (22)	1/26/2000 2:11:00 AM
From: JerryR	Respond to of 35

The 98 annual report discusses the AC vaccine technology. "The ...hapten, is recognized by the immune system and elicits an immune response against the larger molecule. The approach is based on the premise that a patient's immune response to a strongly immunogenic, hapten-modified tumor antigen may be followed by the development of an immune response to the unmodified tumor antigen, somewhat analogous to the phenomenon of drug induced autoimmune disease. Therefore, the process of haptenizing a patient's tumor cells may allow the unhaptenized cancer cells to be recognized by the body's immune system leading to an immune response against the patient's tumor cells and their potential elimination from the body." (I've emphasized the mays.) The results for the survival of stage 3 patients at 5 years being 55% vs 20% in the controls and vs 32% for the high dose alpha interferon seem wonderful and I do not try to minimize their importance or validity. What bothers me is that haptenization changes the antigen. So how does that facilitate a response against the tumor antigen? Is there a theory as to what is going on or does one shrug their shoulders and say, "Hey, it works"? Other questions unrelated to the above: (1) How much tumor is needed to prepare the vaccine? (2) How long does it take? and (3) Should, IYHO, positive biopsies routinely be preserved and if so is that a practical thing to do? At least in my neck of the woods it is not done and that, IMHO, does not seem prudent. Thanks to anyone who may respond. Jerry