Efficacy of Endocrine Therapy Plus Trastuzumab and Pertuzumab vs De-escalated Chemotherapy in Patients with Hormone Receptor-Positive/ERBB2-Positive Early Breast Cancer: The Neoadjuvant WSG-TP-II Randomized Clinical Trial.

Importance: Combination of chemotherapy with (dual) ERBB2 blockade is considered standard in hormone receptor (HR)-positive/ERBB2-positive early breast cancer (EBC). Despite some promising data on endocrine therapy (ET) combination with dual ERBB2 blockade in HR-positive/ERBB2-positive BC, to our knowledge, no prospective comparison of neoadjuvant chemotherapy vs ET plus ERBB2 blockade in particular with focus on molecular markers has yet been performed.

Objective: To determine whether neoadjuvant de-escalated chemotherapy is superior to endocrine therapy, both in combination with pertuzumab and trastuzumab, in a highly heterogeneous HR-positive/ERBB2-positive EBC.

Dual HER2 blockade with pertuzumab (P) and trastuzumab (T) in patients with HER2-positive metastatic breast cancer (mBC) relapsing after adjuvant treatment with T: results from a German non-interventional study (NIS) HELENA (NCT01777958).

Purpose: NIS HELENA documented outcomes in clinical routine practice of first-line therapy with P plus T and docetaxel (D) of patients with advanced HER2-positive BC and prior (neo)adjuvant T.

Methods: Between 06/2013 through 07/2016, 126 patients (in-label use of P at study start = full analysis set, FAS) in 81 German study sites were included. Intense documentation period was limited to 28 treatment cycles.

TP53 mutations are associated with primary endocrine resistance in luminal early breast cancer.

Background: Whereas the genomic landscape of endocrine-resistant breast cancer has been intensely characterized in previously treated cases with local or distant recurrence, comparably little is known about genomic alterations conveying primary non-responsiveness to endocrine treatment in luminal early breast cancer.

Methods: In this study, 622 estrogen receptor-expressing breast cancer cases treated with short-term preoperative endocrine therapy (pET) from the WSG-ADAPT trial (NCT01779206) were analyzed for genetic alterations associated with impaired endocrine proliferative response (EPR) to 3-week pET with tamoxifen or aromatase inhibitors. EPR was categorized as optimal (post-pET Ki67 <10%) versus slightly, moderately, and severely impaired (post-pET Ki67 10%-19%, 20%-34%, and ≥35%, respectively).