{"id":38840,"date":"2025-07-03T11:55:50","date_gmt":"2025-07-03T09:55:50","guid":{"rendered":"https:\/\/www.abcsg.org\/?page_id=38840"},"modified":"2026-02-05T10:00:27","modified_gmt":"2026-02-05T09:00:27","slug":"abcsg-61-study-details","status":"publish","type":"page","link":"https:\/\/www.abcsg.org\/en\/abcsg-studien\/studies-open-for-enrollment\/abcsg-61\/abcsg-61-study-details\/","title":{"rendered":"ABCSG 61 \/ TEODOR Study Details"},"content":{"rendered":"

Neoadjuvant T<\/strong>rE<\/strong>atment O<\/strong>ptimization driven by ctD<\/strong>NA and endO<\/strong>crine R<\/strong>esponsiveness<\/p>\n

A prospective, randomized, controlled, open-label multicenter phase II study investigating neoadjuvant endocrine therapy versus chemotherapy in HR-positive, HER2-negative, ctDNA-negative and endocrine responsive early and locally advanced breast cancer<\/p>\n\n\n\n\n\n\n
Study Start:<\/td>\nQ3\/2025<\/td>\n<\/tr>\n
Coordinating Investigators:<\/td>\nMichael Gnant, Vienna
\nDaniel Egle, Innsbruck<\/td>\n<\/tr>\n
Participants:<\/td>\n256 (national)<\/td>\n<\/tr>\n
Study Design:
\n(Click to enlarge)<\/em><\/td>\n		\"ABCSG<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Treatment:<\/h3>\n

Participants receive 4 weeks of Aromatase Inhibitors (AI) in the initial Run-in Phase, followed by 2:1 randomization in arm A or B or enrolment in arm C in the Main Treatment Phase, depending on ctDNA-status and Ki-67 value of the participant. CtDNA-status is measured centrally by Natera with the SignateraTM-test, for which an (archived) tumor sample and blood are shipped at the beginning of the study. Ki-67 is evaluated locally after 3 weeks of AI therapy in the Run-in Phase.<\/p>\n

If no ctDNA is detected prior to treatment start AND Ki-67 is \u226410% after 3 weeks of AI, the participant is randopmized 2:1 in arm treatment A or B:<\/p>\n

    \n
  • Arm A<\/strong>
    \nAI for 6-8 months (+\/- 30 days) as per Standard of Care. Switch to tamoxifen is allowed, if AI is not tolerated.<\/li>\n
  • Arm B<\/strong>
    \nChemotherapy as per Standard of Care for 8 months (+\/- 30 days)<\/li>\n<\/ul>\n

    Participants, who are ctDNA-positive prior to treatment start OR whose Ki-67 is > 10% after 3 weeks of AI will be enrolled in treatment arm C:<\/p>\n

      \n
    • Arm C<\/strong>
      \nChemotherapy as per Standard of Care for 8 months (+\/- 30 days)<\/li>\n<\/ul>\n

      Primary Objective:<\/h3>\n
        \n
      • To determine the efficacy of endocrine therapy vs chemotherapy in ctDNA-negative and endocrine responsive patients with HR-positive, HER2-negative breast cancer, measured by modified preoperative endocrine prognostic index (PEPI) score.<\/li>\n<\/ul>\n

        Secondary Objectives:<\/h3>\n
          \n
        • To determine the efficacy of endocrine therapy vs chemotherapy in ctDNA- negative and endocrine responsive patients measured by Residual Cancer Burden (RCB).<\/li>\n
        • To determine the difference in breast conservation turn-over rate (BCTOR) between endocrine therapy vs chemotherapy in ctDNA-negative and endocrine responsive patients.<\/li>\n
        • To determine the efficacy of endocrine therapy vs chemotherapy in ctDNA-negative and endocrine responsive patients measured by long-term outcome (event free survival, invasive disease-free survival, invasive breast cancer-free survival, distant recurrence-free survival, and overall survival).<\/li>\n
        • To compare patient reported outcomes of neoadjuvant endocrine therapy (arm A) vs chemotherapy (arm B) in ctDNA- negative and endocrine responsive patients with HR-positive, HER2-negative breast cancer, measured by EORTC QLQ-C30 and QLQ-BR42.<\/li>\n
        • To compare patient reported outcomes of neoadjuvant chemotherapy in ctDNA- negative and endocrine responsive patients (arm B) vs chemotherapy in ctDNA- positive or non-endocrine responsive patients (arm C) with HR-positive, HER2-negative breast cancer, measured by EORTC QLQ-C30 and QLQ-BR42.<\/li>\n
        • To compare patient reported outcomes in patients receiving different adjuvant therapy (arms A, B and C) measured by EORTC QLQ-C30 and QLQ-BR42 after 1-year of follow up from surgery.<\/li>\n<\/ul>\n

          Safety Objectives:<\/h3>\n
            \n
          • To determine the difference in Adverse Events (AEs) between endocrine therapy vs chemotherapy in ctDNA-negative and endocrine responsive patients.<\/li>\n<\/ul>\n

            Exploratory Objectives:<\/h3>\n
              \n
            • To evaluate the kinetics of ctDNA detection across prespecified time points between treatment arms.<\/li>\n
            • To evaluate the association of kinetics of ctDNA detection with surgical and long-term outcome.<\/li>\n<\/ul>\n

              Translational Objectives:<\/h3>\n
                \n
              • To study additional research questions\/ to perform additional analyses from biological material and\/ or clinical data that have been collected within this study.<\/li>\n<\/ul>\n

                Patient Population<\/h3>\n
                  \n
                • The target population of this study consists of patients with ER+\/HER2- early or locally advanced breast cancer (stage IIA-III per AJCC v8) with an indication for chemotherapy and no prior systemic breast cancer specific treatment.<\/li>\n
                • Participants will receive treatment in the Main Treatment Phase based on their ctDNA-status, assessed at the beginning of the trial, measured centrally with the SignateraTM-test and their endocrine response, assessed through the Ki67-value after 3 weeks of initial AI therapy (for details refer to \u201eTreatment\u201c).<\/li>\n<\/ul>\n

                  *Study information is displayed as described in study protocol V1.1. Sites must adhere to the currently approved local version.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

                  Neoadjuvant TrEatment Optimization driven by ctDNA and endOcrine Responsiveness A prospective, randomized, controlled, open-label multicenter phase II study investigating neoadjuvant endocrine therapy versus chemotherapy in HR-positive, HER2-negative, ctDNA-negative and endocrine responsive early and locally advanced breast cancer Study Start: Q3\/2025 Coordinating Investigators: Michael Gnant, Vienna Daniel Egle, Innsbruck Participants: 256 (national) Study Design: (Click to […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":38833,"menu_order":6,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"tags":[],"class_list":["post-38840","page","type-page","status-publish","hentry"],"acf":[],"publishpress_future_action":{"enabled":false,"date":"2026-10-12 18:33:33","action":"delete","newStatus":"draft","terms":[],"taxonomy":"translation_priority","extraData":[]},"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"_links":{"self":[{"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/pages\/38840","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/comments?post=38840"}],"version-history":[{"count":5,"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/pages\/38840\/revisions"}],"predecessor-version":[{"id":40955,"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/pages\/38840\/revisions\/40955"}],"up":[{"embeddable":true,"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/pages\/38833"}],"wp:attachment":[{"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/media?parent=38840"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.abcsg.org\/en\/wp-json\/wp\/v2\/tags?post=38840"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}