Abstract P2-11-06: Plasma assay of methylated DNA markers (MDM) detects patients with metastatic breast cancer (MBC) compared to healthy controls and treated breast cancer patients with no evidence of disease
Authors: Giridhar Karthik V. , Couch Fergus J. , Sinnwell Jason P. , Slettedahl Seth W. , Taylor William R. , Mahoney Douglas W. , Foote Patrick H. , O’Connell Maria C. , Robran Mariah J. , Devens Mary E. , Gonser Anna M. , Larson Nicole , Doering Karen A. , Burger Kelli N. , Kaiser Michael , Allawi Hatim , Ruddy Kathryn , Olson Janet , Kisiel John B. 
Published: March 2023

Abstract
Objective: Aberrantly methylated DNA may be used to detect minimal residual disease or early recurrence in breast cancer. As a 1st step, we aimed to develop an MDM panel to delineate between healthy women, stage I-III breast cancer in remission with no evidence of disease (NED), and metastatic breast cancer (MBC).
Methods: We prospectively enrolled patients into 3 groups: healthy controls (adult females with a normal mammogram in past 12 months with no history of breast cancer), NED [stage I-III breast cancer with no clinical evidence of recurrence 6 months - 3 years post-treatment (adjuvant endocrine therapy allowed)], and MBC (collected either at initial diagnosis of untreated metastatic disease or radiographic progression). DNA was extracted from 6 mL of plasma derived from blood collected in LBgard tubes (Exact Sciences Corp., San Diego CA), and was bisulfite-treated and assayed by target enrichment long-probe quantitative amplified signal (TELQASTM) method for a panel of 15 previously identified MDMs [Table], normalized by the control gene, B3GALT6. Areas under the receiver operating characteristic curve (AUC) were calculated for each MDM to assess discrimination of MBC from other groups. With 60 patients per group, we had greater than 80% power to detect a difference of 0.20 from the null AUC of 0.7.
Results: We tested samples from 60 MBC (10 untreated, 50 recurrent), 60 NED, and 60 healthy women. The median age was 63 (IQR, 55-72) and was not different between groups. The NED group was all hormone-receptor (HR) positive, with 47 (78%) being human epidermal growth factor receptor 2 negative (HER2-) and 13 (22%) HER2+; 48 (80%) were stage I and 9 (15%) were N+. The MBC group had 35 (58%) patients with HR+/HER2- tumors, 11 (18%) HR+/HER2+, and 6 (10%) HR-/HER2-, 4 (7%) HR-/HER2+, with 4 (7%) unknown. Of the 41 MBC whose original stage and nodal status were known 9 (22%) were stage I and 22 (54%) were N+. The markers were able to discriminate between MBC and NED patient samples with AUCs from 0.97 to 0.72. AUCs for 10/15 MDMs (ITPRIPL1, EMX1, C17orf64, OSR2, TRIM67, CHST2, IFFO1, TRH, FAM59B, and MPZ) were &gt;0.90. No difference in MDMs was observed between the healthy and NED groups.
Conclusions: MDMs, assayed from plasma, appear highly discriminant for metastatic breast cancer cases in comparison to control patients with NED or healthy controls. Further clinical validation of this MDM panel in a larger cohort is warranted.
Table 1. Plasma MDM discrimination of metastatic breast cancer (MBC) from healthy controls and previously treated breast cancer patients with no evidence of disease (NED)
Citation Format: Karthik V. Giridhar, Fergus J. Couch, Jason P. Sinnwell, Seth W. Slettedahl, William R. Taylor, Douglas W. Mahoney, Patrick H. Foote, Maria C. O’Connell, Mariah J. Robran, Mary E. Devens, Anna M. Gonser, Nicole Larson, Karen A. Doering, Kelli N. Burger, Michael Kaiser, Hatim Allawi, Kathryn Ruddy, Janet Olson, John B. Kisiel. Plasma assay of methylated DNA markers (MDM) detects patients with metastatic breast cancer (MBC) compared to healthy controls and treated breast cancer patients with no evidence of disease [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-11-06.