TAMOXIFEN LOWERS LIPOPROTEIN(A) 25%-50% IN MEN WITH HEART DISEASE

TAMOXIFEN LOWERS LIPOPROTEIN(A) 25%-50% IN MEN WITH HEART DISEASE, results of a small study presented Nov. 17 at the American Heart Association's 65th Scientific Sessions show. In the study, tamoxifen was given to seven men with severe coronary artery disease and an Lp(a) value greater than 40 ng/ml who were not taking niacin, study investigator David Shewmon, Medical Center of Central Massachusetts, Worcester, reported to AHA. Tamoxifen was given in doses of 10 mg twice a day. Blood samples were taken throughout the three-month treatment phase and at the end of a three-month recovery phase. Use of niacin and neomycin, which lower Lp(a) levels, was not allowed during the study. Two different ELISA assays were used to analyze the blood samples. Explaining the effect of tamoxifen on lipoprotein(a), a form of low- density lipoprotein cholesterol, Shewmon noted that "two of the individuals did not seem to respond." However, "five of the individuals' [Lp(a)] dropped on the order of 25 to 50% over the treatment phase and then did not seem to recover after three months off of the tamoxifen." Shewmon added that "at the eight- and 12-week point, these [the reductions in Lp(a) levels] were statistically significant if you analyze only the responders." But when corrections for multiple comparisons are made "there is no significant difference." The investigator pointed out that "the percent drop in Lp(a) seemed to be dependent on which assay was used," and that "this may have something to do with the degradation of the samples." The lowering of Lp(a) was "more dramatic with the assay using an apoA detection antibody compared to that using an apoB detection antibody," he noted. Shewmon also noted that "two out of three men taking lovastatin [Merck's Mevacor] experienced myalgia during the study." Two of the study subjects "noted a diminished frequency and severity of angina." Summarizing the study results, Shewmon said tamoxifen "lowers Lp(a) in males with [coronary artery disease] and elevated Lp(a) levels." In addition, "Lp(a) levels were not observed to recover to baseline after three months off of tamoxifen although some were going back up." Tamoxifen, an estrogen receptor blocker, has been used in men for treating infertility and painful gynecomastia. FDA's Oncologic Drugs Advisory Committee recently recommended approval of ICI's tamoxifen (Nolvadex) for treating advanced metastatic breast cancer in men, but not for use as adjuvant therapy ("The Pink Sheet" Nov. 23, p. 7). Tamoxifen is approved for treating advanced breast cancer in women and as adjuvant therapy for breast cancer in women. ICI did not participate in Shewmon's study.