INTERFERON PURCHASES EXCEED $5 MIL. ANNUALLY AT MD ANDERSON; GROWTH FACTOR SPENDING HAS HIT $1 MIL./MONTH: COSTS PROMPTING EFFORTS TO "OPTIMIZE" DOSING
Interferon purchases at MD Anderson Cancer Center are over $5 mil. annually, but the Houston center has countered continued growth in interferon use with drug use evaluation activities that have stabilized expenditures, Deputy Pharmacy Division Head Stephen Huber reported to the American Society of Hospital Pharmacists at the group's December clinical meeting in Orlando. "What we've found is [that] because of our [DUE] activities, the optimal biologic dose of interferon has dropped considerably," Huber explained. "We've spent the same amount of money the last two years on interferon and treated twice as many patients. We found out how to dose that drug." MD Anderson currently treats about 2,000 patients a year with interferon. Alpha interferons are approved in the U.S. for Kaposi's sarcoma, hairy cell leukemia, venereal warts, hepatitis C and hepatitis B, for which Schering-Plough's Intron A (interferon alfa-2b) received approval in July 1992. Genentech's gamma interferon product Actimmune was launched in March for the treatment of chronic granulomatous disease, an orphan designation. Despite the progress MD Anderson has made in managing interferons, Huber noted, "there are a whole host of new indications" that will pose further challenges in "pharmacoeconomics." In particular, he predicted, "the antiviral indications are going to be very significant." Among the antiviral indications for which interferons are being studied are delta hepatitis, for use with ddI in AIDS, and in genital and oral herpes. MD Anderson's $5 mil. spending on interferons represents approximately 7% of the institution's projected $75 mil. 1992 drug expenditures. Huber estimated that 30% of those expenditures will have been spent on biotechnology products in 1992. During the previous year, 18% of drug spending at MD Anderson was on biotech products, and in 1990, 15% of a $40 mil. drug budget. The cancer center is confronting the rising cost of biotechnology agents with examinations of optimal dosing. The aim, Huber said, is "to give people access [to the products] and then monitor the therapy so we can get better data to figure out who should be getting the therapies." Questions arise because "we get the product released, many times for a targeted, narrow, orphan- type indication, and then it's used in other areas, where obviously the dose might be different; we really don't know what the ideal dose is for many of these products," Huber told ASHP. To govern the "million dollars a month" MD Anderson is spending on growth factors, the center has been developing a database of all patients who receive colony stimulating factors at the institution. "Our early data showed that many of the physicians were prescribing the drugs on a standard basis, 5 mu/kg, given 14 days," Huber said. After looking at dosing patterns, however, the center found that "maybe we didn't need 14 days...that therapeutically we'd get the same outcome with 10 days." And that, Huber noted, is "a difference of around $400 to $800 in drug cost." Approximately 2,400 patients per year are treated with CSFs at MD Anderson. Kaiser Permanente, Northwest Region, a Portland, Ore.-based managed care facility, also found that it could reduce the dose of G-CSF in some cases. Kaiser found that in "intermediate risk patients" who did not have a fever or neutropenia after their first course of chemotherapy, "we were able to lower the dose of G-CSF from 5 mu/kg to 3 mu/kg and on some patients to 1-1/2 mu/kg and maintain our outcomes, meaning chemotherapy doses were maintained," Oncology Pharmacist Specialist Dan Colley told ASHP. Colley presented information on Kaiser's "cytokine dosing service," which has developed guidelines for G-CSF and erythropoietin use, at an ASHP "exhibitor's seminar" sponsored by Ortho. Sales of the colony stimulating factors G-CSF and GM-CSF took off rapidly following their 1991 launches. Both Amgen, with sales of its recombinant granulocyte-colony stimulating factor Neupogen (G-CSF), and Immunex, with sales of its granulocyte macrophage- colony stimulating factor Leukine (GM-CSF), achieved record earnings in 1991 following product launches in the first quarter of the year ("The Pink Sheet" Feb. 10, 1992, p. 15). Hoechst continues to market its GM-CSF product Prokine pending Federal Trade Commission review of the settlement the two companies reached in July. G-CSF is used more frequently at MD Anderson. "Prokine and Leukine...have not not made as much of a splash, if you will...partly because of the indication differences," Huber explained. Neupogen is indicated for the decrease of infection in non-myeloid malignancies in patients receiving myelosuppressive chemotherapy. Prokine and Leukine both are indicated for myeloid reconstruction following autologous bone marrow transplant; GM-CSF is indicated as well for bone marrow transplant failure or engraftment delay. MD Anderson has improved its reimbursement record for off- label usage of biosynthetic erythropoietin from 40% to 60% by providing documentation of the justification for use, Huber said. The center has been able to improve its record with the publication of trials providing safety and efficacy information for EPO. Anemia induced by cancer or by chemotherapy is the major area of erythropoietin use at MD Anderson. Amgen's Epogen (epoetin alfa), licensed to Ortho as Procrit, is approved to date only for the treatment of anemia associated with chronic renal failure or with AZT treatment of HIV infection. Ortho, which has rights to EPO in non-dialysis markets, has a PLA pending for cancer- or chemotherapy-induced anemia. "What we're seeing now is just the tip of the iceberg of some of the biotechnology products," Huber predicted. If erythropoietin receives approval for use in autologous blood transfusions, "that could drive the erythropoietin market well above the billion dollar mark." Kaiser Northwest has incorporated guidelines for the use of erythropoietin in cancer- and chemotherapy-associated anemia into its cytokine dosing service. Kaiser's current guidelines for use of erythropoietin begin with an initial dose of 150 units/kg three times a week. After four weeks, estimated as the time it takes most patients to respond, the dose in nonresponders is increased to 300 units three times/week. At eight weeks, if no response is seen, treatment is stopped. Colley said response is measured by Kaiser's dosing service not only as "a rising hematocrit [volume percentage of erythrocytes in whole blood] of six percentage points or so, but [also by asking] did the patients symptoms go away -- did the angina improve, did fatigue improve. If the baseline symptoms aren't ameliorated it doesn't make sense to continue a patient on erythropoietin just to raise their hematocrit levels up," he explained. If a patient responds quickly, the dose is held steady until the response decreases and then is halved. In all cases, the dose is individualized to maintain the hematocrit level in the "target range," which "ought to be wherever the symptoms disappear in the patient," Colley said. "That may be 35% [the original dose] in some patients, while in some patients it might be lower and in others it may be higher." Other elements of the system include patient selection based on factors such as ability to adhere to therapy and baseline endogenous erythropoietin levels; and the elimination of other causes of anemia, such as B or iron deficiency.
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