Abstract Introduction Cyclophosphamide-based adjuvant chemotherapy is a mainstay of treatment for women with node-positive breast cancer, but is not universally effective in preventing recurrence. Pharmacogenetic variability in drug metabolism is one possible mechanism of treatment failure. We hypothesize that functional single nucleotide polymorphisms (SNPs) in drug metabolizing enzymes (DMEs) that activate (CYPs) or metabolize (GSTs) cyclophosphamide account for some of the observed variability in disease outcomes. Methods We performed a retrospective cohort study of 350 women enrolled in a multicenter, randomized, adjuvant breast cancer chemotherapy trial (ECOG-2190/INT-0121). Subjects in this trial received standard-dose cyclophosphamide, doxorubicin and fluorouracil (CAF), followed by either observation or high-dose cyclophosphamide and thiotepa with stem cell rescue. We used bone marrow stem cell-derived genomic DNA from archival specimens to genotype CYP2B6, CYP2C9, CYP2D6, CYP3A4, CYP3A5, GSTM1, GSTT1, and GSTP1. Cox regression models were computed to determine associations between genotypes (individually or in combination) and disease-free survival (DFS) or overall survival (OS), adjusting for confounding clinical variables. Results In the full multivariable analysis, women with at least one CYP3A4 *1B variant allele had significantly worse DFS than those who were wild-type *1A/*1A (multivariate hazard ratio 2.79; 95% CI 1.52, 5.14). CYP2D6 genotype did not impact this association among patients with estrogen receptor (ER) -positive tumors scheduled to receive tamoxifen. Conclusions These data support the hypothesis that genetic variability in cyclophosphamide metabolism independently impacts outcome from adjuvant chemotherapy for breast cancer.

BACKGROUND: Stakeholder involvement in health care research has been shown to improve research development, processes, and dissemination. The literature is developing on stakeholder engagement methods and preliminarily validated tools for evaluating stakeholder level of engagement have been proposed for specific stakeholder groups and settings. OBJECTIVES: This paper describes the methodology for engaging a Study Advisory Committee (SAC) in research and reports on the use of a stakeholder engagement survey for measuring level of engagement. METHODS: Stakeholders with previous research connections were recruited to the SAC during the planning process for a multicenter randomized control clinical trial, which is ongoing at the time of this writing. All SAC meetings undergo qualitative analysis, while the Stakeholder Engagement Survey instrument developed by the Patient-Centered Outcomes Research Institute (PCORI) is distributed annually for quantitative evaluation. RESULTS: The trials SAC is composed of 18 members from 3 stakeholder groups: patients and their caregivers; patient advocacy organizations; and health care payers. After an initial in-person meeting, the SAC meets quarterly by telephone and annually in-person. The SAC monitors research progress and provides feedback on all study processes. The stakeholder engagement survey reveals improved engagement over time as well as continued challenges. CONCLUSIONS: Stakeholder engagement in the research process has meaningfully contributed to the study design, patient recruitment, and preliminary analysis of findings.

Study advisory committees (SACs) provide critical value to clinical trials by providing unique perspectives that pull from personal and professional experiences related to the trials healthcare topic. The Emergency Medicine Palliative Care Access (EMPallA) study had the privilege of convening a 16-person SAC from the projects inception to completion. The study team wanted to understand the impact this project had on the SAC members. In this narrative, we use reflective dialogue to share SAC members lived experiences and the impact the EMPallA study has had on members both personally and professionally. We detail the (1) benefits SAC members, specifically patients, and caregivers, have had through working on this project. (2) The importance of recruiting diverse SAC members with different lived experiences and leveraging their feedback in clinical research. (3) Value of community capacity building to ensure the common vision of the clinical trial is promoted.