Abstract B78: Final results of a prospective observational study comparing African American and Caucasian patients receiving second-line treatment with pemetrexed for advanced non-small cell lung cancer (NSCLC)

Abstract

Abstract Background: Few prospective studies have evaluated the impact of race and ethnicity on clinical outcomes, during lung cancer treatment. This prospective observational study evaluated the impact of ethnicity on disease control rate (DCR) in patients with NSCLC treated with second-line pemetrexed (P). Methods: Eligibility criteria included stage IIIB or IV NSCLC pts receiving single-agent P for second-line therapy in routine clinical practice. Sites were selected to ensure high minority representation. Due to persistent challenges in achieving desired enrollment of minority, the focus of the study was narrowed to a comparison of patients self-reporting as either Caucasian (C) or African American (AA). This report describes findings regarding the primary endpoint of the study, DCR. Non-inferiority was evaluated using logistic regression analysis for DCR controlling for predefined covariates: age, gender, income, marital status, insurance type, smoking status, ECOG performance score, disease stage, histology, comorbidities, time from end of first-line to initiation with P, prior exposure to first-line platinum, exposure to first-line paclitaxel, and number of first-line cycles. The DCR of AAs was considered non-inferior to Cs if the upper 95% confidence bound on the adjusted odds ratio (OR) for Cs vs AAs was less than 1.78, corresponding to a difference in proportion of 14% assuming Cs to have a DCR of approximately 50%. The pre-specified bound was chosen to be one-half of the anticipated difference between treatment and no second-line treatment. Secondary endpoints reported here include progression-free survival (PFS) and overall survival (OS). Results: The unadjusted DCR was 43.4% (116/267) for C and 45.8% (27/59) for AA (unadjusted OR=0.91). The adjusted OR for the comparison of C to AA in the final logistic regression model was 0.79 (95% CI, 0.41, 1.51). This upper 95% confidence bound was within the pre-specified acceptable bound of 1.78. Median PFS times were 2.7 months (95% CI: 2.4, 3.4) for Cs and 3.0 months (95% CI: 2.3, 4.7) for AAs (P=0.91). Median OS times were 6.7 months (95% CI, 5.7, 7.9) for Caucasians and 6.9 months (95% CI: 4.5, 8.9) for AAs (P=0.92). Conclusions: Based on pre-specified analyses, DCR of AAs was non-inferior to Cs. The adjusted and unadjusted OR (0.79 and 0.91) were in favor of AA. Hence, ethnicity is not considered a significant predictor of disease control following second-line treatment with P. Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):B78.