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558 Background: Tamoxifen is a selective estrogen receptor modulator (SERM) that is commonly used to treat breast cancer. However, despite its established efficacy, recent studies indicate that 1) more than 50 percent of individuals will discontinue treatment prior to completing the recommended five-year therapeutic regimen and 2) the likelihood of discontinuation is moderated by the presence of polymorphisms in the gene encoding cytochrome P450 2D6 (CYP2D6), the enzyme responsible for metabolizing tamoxifen into its active form. Methods: We measured tamoxifen persistency rates in a cohort of breast cancer patients to test the hypothesis that tamoxifen adherence is modified by the dose administered and concomitant use of anti-depressant (SSRI) drugs known to interfere with CYP2D6 metabolism. Study subjects (N = 12,742) were identified in a large transactional claims database, cross-classified by tamoxifen dose (HIGH, NORMAL) and SSRI status (YES, NO), and followed for 360 days after initiation of therapy....

7077 Background: Recommendations for baseline and quarterly measurement of the BCR-ABL fusion transcript to monitor imatinib response in patients with chronic myelogenous leukemia (CML) were formally introduced in October 2006, and have been incorporated into nationally recognized treatment guidelines. Methods: To assess BCR-ABL testing rates, we conducted a retrospective cohort analysis using a >10 million-member health plan database comprised of integrated pharmacy and medical claims. The study cohort was defined as patients with an index imatinib pharmacy claim from July 1, 2006, to December 31, 2006, who had a CML diagnosis (ICD-9 205.1X; N = 504), and a minimum of 3 months continuous follow-up by claims history (N = 465). Over a period of up to four quarters from the index imatinib prescription date, BCR-ABL testing in each quarter was assessed by the presence of any of a set of 19 CPT-4 codes. BCR-ABL testing rates in each individual quarter and in consecutive quarters were measured. Results: The overall study cohort was 57% male; mean (±SD) age was 52±14 y/o, with 26% 19–44 y/o, 57% 45–64 y/o, and 15% ≥65 y/o. Median duration of f/u was 559 days (interquartile range 302–628 days), and a cohort of 359 patients had 4 quarters of f/u. At least one BCR-ABL test was recorded in 60% of patients. The rate of first quarter BCR-ABL testing was 40%, and remained at 42%-43% in quarters 2 thru 4. Consecutive quarterly testing rates were 24% through the second quarter, 18% through the third quarter, and 14% through the fourth quarter. Conclusions: In this retrospective claims database analysis, only 14% of a large cohort of CML patients treated with imatinib had BCR-ABL testing recorded in each of 4 consecutive quarters. Inadequate compliance with recommended BCR-ABL testing can delay treatment decisions, and may be associated with poor clinical outcome. [Table: see text]

14696 Background: Epidermal growth factor receptor (EGFR) is an attractive target for anti-cancer agents, which have shown activity against various types of tumors. Skin/eye toxicity is a class adverse effect associated with anti-EGFR therapy. This project aims to determine whether skin/eye toxicity can be used as a biomarker for dose selection of anti-EGFR agents. Methods: Extract information on dose and skin/eye toxicity from datasets of FDA approved anti-EGFR agents; Tabulate the percentage of subjects with skin/eye toxicity and perform sigmoidal Emax modeling to estimate the dose associated with maximum skin/eye toxicity; Compare the model estimated dose and the label recommended dose; Determine the capability using skin/eye toxicity as a measure for dose selection for anti-EGFR agents. Results: Skin/eye toxicity data were obtained from all six FDA approved anti-EGFR agents. The sigmoidal Emax model fit the data from trials of Drug A, Drug B and Drug C well, and the predicted dose matched the label re...