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. Design, Setting, and Participants: This prospective, multicenter, neoadjuvant randomized clinical trial allocated 207 patients with centrally confirmed estrogen receptor-positive and/or progesterone receptor-positive (>1%) HR-positive/ERBB2-positive EBC to 12 weeks of standard ET (n = 100) vs paclitaxel (n = 107) plus trastuzumab and pertuzumab. A total of 186 patients were required to detect a statistically significant difference in pathological complete response (pCR) (assumptions: 19% absolute difference in pCR; power, ≥80%; 1-sided Fisher exact test, 2.5% significance level). Interventions: Standard ET (aromatase inhibitor or tamoxifen) or paclitaxel, 80 mg/m2, weekly plus trastuzumab and pertuzumab every 21 days. Main Outcomes and Measures: The primary end point was pCR (ypT0/is, ypN0). Secondary end points included safety, translational research, and health-related quality of life. Omission of further chemotherapy was allowed in patients with pCR. PAM50 analysis was performed on baseline tumor biopsies. Results: Of the 207 patients included (median [range] age, 53 [25-83] years), 121 (58%) had cT2 to cT4 tumors, and 58 (28%) had clinically node-positive EBC. The pCR rate in the ET plus trastuzumab and pertuzumab arm was 23.7% (95% CI, 15.7%-33.4%) vs 56.4% (95% CI, 46.2%-66.3%) in the paclitaxel plus trastuzumab and pertuzumab arm (odds ratio, 0.24; 95% CI, 0.12-0.46; P < .001). Both immunohistochemical ERBB2 score of 3 or higher and ERBB2-enriched subtype were independent predictors for pCR in both arms. Paclitaxel was superior to ET only in the first through third quartiles but not in the highest ERBB2 quartile by messenger RNA. In contrast with the paclitaxel plus trastuzumab and pertuzumab arm, no decrease in health-related quality of life after 12 weeks was observed in the ET plus trastuzumab and pertuzumab arm. Conclusions and Relevance: The WSG-TP-II randomized clinical trial is, to our knowledge, the first prospective trial comparing 2 neoadjuvant de-escalation treatments in HR-positive/ERBB2-positive EBC and demonstrated an excellent pCR rate after 12 weeks of paclitaxel plus trastuzumab and pertuzumab that was clearly superior to the pCR rate after ET plus trastuzumab and pertuzumab. Trial Registration: ClinicalTrials.gov Identifier: NCT03272477.

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. Maximum follow-up (FU) was 24 months (mos). Safety was assessed in the safety set (SAF = eligible patients with at least one dose of P, n = 132). Median progression-free survival (PFS) was the main parameter of interest. RESULTS: Mean age of FAS patients was 55.1 [30.7-80.2] years, 81.7% (95.2%) were < 65 (75) years of age. 51.6% of the FAS patients were hormone receptor-positive (HR+), 91.3% had distant, 73.0% visceral, and 18.3% non-visceral metastases. Median disease-free interval was 40.2 [6.6-95.9] mos. Effectiveness (FAS): Median PFS was 18.8 [15.1; 24.2] mos. Overall response rate was 64.3% (55.6; 72.1). Median overall survival was 55.9 mos [41.2, not reached]. Safety (SAF): 93.9% of patients had an adverse event (AE), 32.6% a serious AE (SAE). AEs related to P occurred in 53.8% of SAF, SAEs related to P in 13.6%. Diarrhea was the most frequently reported related (S)AE. There were 8 (6.1%) patients with a fatal AE. CONCLUSION: Based on the outcomes from NIS HELENA, results of dual blockade with P+T in patients relapsing after (neo)adjuvant T as reported from the CLEOPATRA study (NCT01777958) can be transferred to routine clinical practice. No new safety signals were detected.

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). Recently described gene mutations frequently found in previously treated advanced breast cancer were analyzed (ARID1A, BRAF, ERBB2, ESR1, GATA3, HRAS, KRAS, NRAS, PIK3CA, and TP53) by next-generation sequencing. Amplifications of CCND1, FGFR1, ERBB2, and PAK1 were determined by digital PCR or fluorescence in situ hybridization. RESULTS: ERBB2 amplification (p = 0.0015) and mutations of TP53 (p < 0.0001) were significantly associated with impaired EPR. Impaired EPR in TP53-mutated breast cancer cases was independent from the Oncotype DX Recurrence Score group and was seen both with tamoxifen- and aromatase inhibitor-based pET (p = 0.0005 each). CONCLUSION: We conclude that impaired EPR to pET is suitable to identify cases with primary endocrine resistance in early luminal breast cancer and that TP53-mutated luminal cancers might not be sufficiently treated by endocrine therapy alone.