Supplementary materials: Matching-adjusted indirect comparison of ribociclib + nonsteroidal aromatase inhibitor versus abemaciclib + endocrine therapy in hormone receptor-positive/HER2-negative early breast cancer

<b>These are peer-reviewed supplementary materials for the article</b><b> </b><b>'</b><b>Matching-adjusted indirect comparison of </b><b>ribociclib + nonsteroidal aromatase </b><b>inhibitor versus abemaciclib + endocrine </b><b>therapy in hormone </b><b>receptor-positive/HER2-negative early </b><b>breast cancer</b><b>'</b><b> </b><b>published in the</b><b> </b><b><i>Journal of Comparative Effectiveness Research</i></b><b>.</b><b>Supplementary Table 1: </b>Search terms used for systematic literature search<b>Supplementary Table 2: </b>Study characteristics of trials with patients classified as high-risk<b>Supplementary Table 3: </b>Overview of the NATALEE and monarchE trials<b>Supplementary Table 4: </b>Clinician ranking of prognostic factors<b>Supplementary Table 5: </b>Summary of quantitative tests for treatment effect modifiers and prognostic factors using individual patient data on iDFS from the selected-NATALEE patient population<b>Supplementary Table 6: </b>Unadjusted baseline characteristics in monarchE cohort 1 and selected-NATALEE patient population<b>Supplementary Table 7: </b>Primary analysis: patient characteristics before and after weighting in the selected-NATALEE patient population<b>Supplementary Table 8: </b>Sensitivity analysis 1 (A) and 2 (B): Cox regressions of iDFS comparisons in monarchE cohort 1 and selected-NATALEE patient population<b>Supplementary Table 9: </b>Sensitivity analysis 1 (A) and 2 (B): Cox regressions of DRFS comparisons in monarchE cohort 1 and selected-NATALEE patient population<b>Supplementary Table 10: </b>Primary analysis: comparison of treatment-emergent adverse events in monarchE cohort 1 and selected-NATALEE patient population<b>Supplementary Table 11: </b>Sensitivity analysis 1 (A) and 2 (B): comparison of treatment-emergent adverse events in monarchE cohort 1 and selected-NATALEE patient population<b>Supplementary Figure 1: </b>Forest plot of iDFS hazard ratios in selected-NATALEE patient population with interaction tests<b>Supplementary Figure 2: </b>Primary analysis: histogram of MAIC weights<b>Supplementary Figure 3: </b>Primary analysis: proportional hazards assumption test for iDFS based on Schoenfeld residuals<b>Supplementary Figure 4: </b>Primary analysis: proportional hazards assumption test for DRFS based on Schoenfeld residuals<b>Aim:</b> Ribociclib + nonsteroidal aromatase inhibitor (NSAI) and abemaciclib + endocrine therapy (ET) are approved for high-risk hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) early breast cancer based on data from the NATALEE and monarchE trials, respectively. No trials have directly compared efficacy and safety of adjuvant ribociclib and abemaciclib. This study compared relative efficacy and safety of adjuvant ribociclib + NSAI versus abemaciclib + ET using matching-adjusted indirect comparison (MAIC). <b>Materials &amp; methods:</b> Individual patient data from NATALEE and aggregate data from monarchE were analyzed, with patients from NATALEE selected to match the key eligibility criteria of monarchE cohort 1. Unanchored MAIC was used to compare invasive disease-free survival, distant relapse–free survival, and grade ≥3 treatment-emergent adverse events between treatment arms in NATALEE versus monarchE. Cox regression was used to estimate hazard ratios pre- and post-MAIC weighting. Logistic regression was used to estimate odds ratios (ORs). <b>Results:</b> After weighting, the effective sample size for the ribociclib + NSAI arm of NATALEE was 448. Cox regression yielded similar invasive disease-free survival with weighted ribociclib + NSAI versus abemaciclib + ET (hazard ratio, 0.901; 95% CI: 0.678–1.197). Unweighted efficacy comparisons were consistent with the weighted approach. Lower odds (OR &lt;1) for diarrhea, leukopenia and lymphopenia and higher odds (OR &gt;1) for increased alanine aminotransferase and neutropenia with ribociclib + NSAI versus abemaciclib + ET were noted before and after weighting. Sensitivity analyses were consistent with the primary analysis. <b>Conclusion:</b> This MAIC suggests similar efficacy between ribociclib + NSAI and abemaciclib + ET but different safety profiles in the HR+/HER2- early breast cancer patient population corresponding to the monarchE cohort 1, which has implications for treatment decisions. This analysis has limitations inherent to unanchored MAIC and should be interpreted in context of the trials and withclinical judgement.<br>