CYTOGEN PLANS TO FILE PLA FOR ONCOSCINT-PROSTATE IN "EARLY 1993"

CYTOGEN PLANS TO FILE PLA FOR ONCOSCINT-PROSTATE IN "EARLY 1993," President Thomas McKearn, MD/PhD, told the New York Society of Security Analysts Sept. 16. The murine monoclonal antibodies used in the Cytogen prostate cancer diagnostic "provoke a human anti-mouse antibody, or HAMA, response in only about 5% of patients," and are "administered at doses approximately one half" that of antibodies used in OncoScint-ovarian and colorectal, he noted. The level of HAMA response in monoclonal antibody-based diagnostic products has been a subject of inquiry by FDA's Biological Response Modifiers Advisory Committee. During its review last January of OncoScint, the committee expressed concerns with the 40% HAMA response rate found in ovarian cancer and colorectal cancer clinical studies but decided unanimously to recommend the diagnostic for approval, concluding that it had clinical utility in a selected subset of patients ("The Pink Sheet" Jan. 20, p. 5). Princeton, N.J.-based Cytogen plans to apply for approval of OncoScint-ovarian and colorectal cancer diagnosis for multiple use upon receiving approval for single use. The company said that in about 105 patients, "the same sensitivity...efficacy and the same safety [was seen] upon repeat administration as was seen upon first administration of the agent" during diagnostic procedures for ovarian and colorectal cancer detection. The PLAs for OncoScint-ovarian and colorectal have been pending at FDA since March 1990 and September 1989, respectively, and it has been nine months since the advisory committee's affirmative recommendation. Cytogen had hoped to market the products in the U.S. by June. Commenting on the pending status at FDA, McKearn told the analysts that: "In our opinion, there is no valid reason for a delay of this kind." Chief Financial Officer Martin Cleary said the products are "proceeding through the final steps toward FDA marketing approval." In response to a question, McKearn said that Cytogen is working on a human monoclonal antibody to replace the mouse-derived MAb in the company's OncoRad cancer therapy products. "The question, I think, derives from a suspicion we share that one should be looking to humanized antibodies, certainly in the therapy setting, so that the [HAMA] response will not enter into any of the limitations to that therapy," he added. Cytogen's lead cancer therapy product, OncoRad-ovarian, is currently in Phase II trials. Cytogen has tested the therapy in a total of about 130-140 patients to date. The firm plans to go to FDA with its early Phase II data and request expedited review of the cancer therapy product, McKearn said. In Phase I studies in end-stage ovarian cancer patients, the maximum tolerated dose of radioisotope Yttrium 90 delivered was 35 millicuries. Cytogen noted that among the Phase I patients, two patients dosed at approximately 15 millicuries and above underwent durable remissions and one experienced tumor response. Cleary conceded at the analysts meeting that Cytogen is "disappointed with the level of sales achieved to date" of OncoScint in Europe. Cytogen's portion of the diagnostic's sales for the first six months of 1992 was $337,000; the firm expects only "slightly more" revenues from European sales in the second half of the year. Cleary noted that Cytogen "never really looked to the European activity as being a major contributor to our economics in the short or long term." OncoScint-colorectal received a marketing recommendation from the European Community's Committee for Proprietary Medicinal Products in June 1991 and has been launched in six Western European countries. Cleary pointed to the European nuclear medicine community as the sticking point in greater acceptance of OncoScint, saying they have "hampered our sales effort to date." Noting that "the oncologists and surgeons in Europe see real benefit to OncoScint," Cleary acknowledged, however, that "the nuclear medicine physicians must perform and interpret the OncoScint scans. Our investigations told us...that these doctors were not accustomed to this new procedure, and require more extensive training with OncoScint before...they are comfortable using OncoScint routinely." To correct the problem, Cytogen and its European marketing and distribution partner EuroCetus have stepped up marketing efforts directed at nuclear medicine physicians, including a training symposium, one-on-one training sessions and the hiring of a consulting firm to assist in marketing. The slow acceptance of OncoScint in Europe has affected Cytogen's U.S. marketing plan for OncoScint as well. Cleary noted that the Cytogen portion of the OncoScint sales force, "now numbering 13, has been largely drawn from the nuclear medicine industry." Cytogen has a U.S. copromotional agreement with BASF's Knoll Pharmaceuticals.