Neoadjuvant palbociclib plus either giredestrant or anastrozole in oestrogen receptor-positive, HER2-negative, early breast cancer (coopERA Breast Cancer): an open-label, randomised, controlled, phase 2 study

BACKGROUND

The development of more potent selective oestrogen receptor antagonists and degraders (SERDs) that can be orally administered could help to address the limitations of current endocrine therapies. We report the primary and final analyses of the coopERA Breast Cancer study, designed to test whether giredestrant, a highly potent, non-steroidal, oral SERD, would show a stronger anti-proliferative effect than anastrozole after 2 weeks for oestrogen receptor-positive, HER2-negative, untreated early breast cancer.

METHODS

In this open-label, randomised, controlled, phase 2 study, postmenopausal women were eligible if they were aged 18 years or older; had clinical T stage (cT)1c to cT4a-c (≥1·5 cm within cT1c) oestrogen receptor-positive, HER2-negative, untreated early breast cancer; an Eastern Cooperative Oncology Group performance status of 0-1; and baseline Ki67 score of at least 5%. The study was conducted at 59 hospital or clinic sites in 11 countries globally. Participants were randomly assigned (1:1) to giredestrant 30 mg oral daily or anastrozole 1 mg oral daily on days 1-14 (window-of-opportunity phase) via an interactive web-based system with permuted-block randomisation with block size of four. Randomisation was stratified by cT stage, baseline Ki67 score, and progesterone receptor status. A 16-week neoadjuvant phase comprised the same regimen plus palbociclib 125 mg oral daily on days 1-21 of a 28-day cycle, for four cycles. The primary endpoint was geometric mean relative Ki67 score change from baseline to week 2 in patients with complete central Ki67 scores at baseline and week 2 (window-of-opportunity phase). Safety was assessed in all patients who received at least one dose of study drug. The study is registered with ClinicalTrials.gov (NCT04436744) and is complete.

FINDINGS

Between Sept 4, 2020, and June 22, 2021, 221 patients were enrolled and randomly assigned to the giredestrant plus palbociclib group (n=112; median age 62·0 years [IQR 57·0-68·5]) or anastrozole plus palbociclib group (n=109; median age 62·0 [57·0-67·0] years). 15 (7%) of 221 patients were Asian, three (1%) were Black or African American, 194 (88%) were White, and nine (4%) were unknown races. At data cutoff for the primary analysis (July 19, 2021), the geometric mean relative reduction of Ki67 from baseline to week 2 was -75% (95% CI -80 to -70) with giredestrant and -67% (-73 to -59) with anastrozole (p=0·043), meeting the primary endpoint. At the final analysis (data cutoff Nov 24, 2021), the most common grade 3-4 adverse events were neutropenia (29 [26%] of 112 in the giredestrant plus palbociclib group vs 29 [27%] of 109 in the anastrozole plus palbociclib group) and decreased neutrophil count (17 [15%] vs 16 [15%]). Serious adverse events occurred in five (4%) patients in the giredestrant plus palbociclib group and in two (2%) patients in the anastrozole plus palbociclib group. There were no treatment-related deaths. One patient died due to an adverse event in the giredestrant plus palbociclib group (myocardial infarction).

INTERPRETATION

Giredestrant offers encouraging anti-proliferative and anti-tumour activity and was well tolerated, both as a single agent and in combination with palbociclib. Results justify further investigation in ongoing trials.

FUNDING

F Hoffmann-La Roche.

Neoadjuvant giredestrant (GDC-9545) plus palbociclib (P) versus anastrozole (A) plus P in postmenopausal women with estrogen receptor–positive, HER2-negative, untreated early breast cancer (ER+/HER2– eBC): Final analysis of the randomized, open-label, international phase 2 coopERA BC study

589

Background: Endocrine therapy (ET) is the therapeutic mainstay for ER+ BC. Giredestrant is a highly potent, nonsteroidal, oral, selective ER antagonist and degrader (SERD) which has demonstrated robust ER occupancy, is well tolerated, and has previously shown encouraging antitumor activity as monotherapy and in combination with P in metastatic BC. coopERA BC (NCT04436744) evaluated giredestrant in eBC and met its primary endpoint, highlighting superior Ki67 suppression with single-agent giredestrant vs A at Week 2. Giredestrant was well tolerated. Here, we report the final analysis. Methods: Eligible patients (pts) with measurable ER+/HER2– untreated eBC and baseline Ki67 score ≥5% (202 planned) were randomized 1:1 to receive, on Days 1–14 of a neoadjuvant window-of-opportunity phase, 30 mg oral daily (PO QD) giredestrant or 1 mg PO QD A followed by a 16-week neoadjuvant phase of QD giredestrant or A for four 28-day cycles with 125 mg PO P on Days 1–21. Randomization was stratified by tumor size, baseline Ki67 score, and progesterone receptor status. Endpoints assessed here included Ki67 suppression from baseline to surgery, complete cell cycle arrest (CCCA; Ki67 ≤2.7%) at surgery, objective response rate (ORR), and safety. Results: At final analysis (cutoff: Nov 24, 2021), 112 and 109 pts were randomized to the giredestrant and A arms, respectively (median age: 62 years each; stage I/IIa disease: 60% vs 54%). Consistent with the primary analysis, greater suppression of Ki67 was observed at surgery with giredestrant + P (–81% [95% confidence interval (CI): –86%, –75%]) vs A + P (–74% [95% CI: –80%, –67%]). Similarly, greater CCCA was achieved at surgery with giredestrant + P (20%) vs A + P (14%). ORR was similar between the two arms (giredestrant + P: 50% [95% CI: 40%, 60%]; A + P: 49% [95% CI: 39%, 59%]). ET-related adverse events (AEs) were non-serious and occurred at similar rates between the two arms. Related Grade ≥3 AE rates were also similar at 6% each. Interruption/withdrawal of ET due to AEs was low and similar for both arms. Conclusions: In this final analysis of coopERA BC, the greater suppression of Ki67 with giredestrant vs A observed at Week 2 in the primary analysis was maintained at surgery, and safety data remained consistent with the known safety profile of giredestrant. coopERA BC is the first randomized study to show superior antiproliferative activity of an oral SERD (giredestrant) over an aromatase inhibitor (A) in ER+/HER2– eBC; studies are ongoing to further assess giredestrant’s clinical benefit. Clinical trial information: NCT04436744.

Abstract PD13-06: Neoadjuvant giredestrant (GDC-9545) + palbociclib versus anastrozole + palbociclib in postmenopausal women with estrogen receptor-positive, HER2-negative, untreated early breast cancer: Primary analysis of the randomized, open-label, phase II coopERA breast cancer study

Background Endocrine therapy, the therapeutic mainstay for estrogen receptor-positive breast cancer, targets estrogen receptor activity and/or estrogen synthesis. CDK4/6 inhibitors cause cell cycle arrest and significantly decrease expression of the proliferation biomarker Ki67 when used in conjunction with aromatase inhibitors such as anastrozole. Giredestrant, a highly potent, nonsteroidal, oral, selective estrogen receptor antagonist and degrader, achieves robust estrogen receptor occupancy, is well tolerated, and has encouraging antitumor activity as a monotherapy and in combination with the CDK4/6 inhibitor palbociclib in metastatic breast cancer. coopERA Breast Cancer (NCT04436744) is a phase II study investigating 2 weeks of giredestrant versus anastrozole in a window-of-opportunity phase, followed by 4 months of giredestrant plus palbociclib versus anastrozole plus palbociclib in a neoadjuvant phase in postmenopausal women with estrogen receptor-positive, HER2-negative, untreated early breast cancer. We will report the results of the primary analysis. Methods Eligible patients who had measurable cT1c (≥1.5 cm)-cT4a-c estrogen receptor-positive, HER2-negative, untreated early breast cancer and baseline Ki67 score ≥5% were randomized 1:1 to 1 mg oral, daily anastrozole or 30 mg oral, daily giredestrant on Days 1-14 (window-of-opportunity phase lasting 14 days) followed by daily dosing for four 28-day cycles in combination with 125 mg oral palbociclib on Days 1-21 (neoadjuvant phase lasting 16 weeks) before surgery. Patients were stratified according to T status, Ki67 score, and progesterone receptor status. The primary efficacy endpoint was centrally assessed geometric mean relative Ki67 score change from baseline to Week 2 during the window-of-opportunity phase, which is reflective of the ability of endocrine therapies to suppress tumor-cell proliferation, and is a surrogate marker for clinical outcomes. The secondary efficacy endpoint is complete cell cycle arrest rate (CCCA), defined as Ki67 score ≤2.7%, at Week 2. Safety was also assessed. Results Results of a previous interim analysis (including 83 of the planned 202 patients) demonstrated a greater relative reduction of Ki67 at 2 weeks with giredestrant (reduction from baseline to Week 2 geometric mean = 80%; 95% CI = -85%, -72%) compared with anastrozole (reduction from baseline to Week 2 geometric mean = 67%; 95% CI = -75%, -56%; P = 0.0222). Similarly, consistent Ki67 suppression was observed in patients with baseline Ki67 ≥20% (83% reduction with giredestrant versus 71% reduction with anastrozole) or <20% (65% versus 24% reductions). At Week 2, 25% of tumors exhibited CCCA with giredestrant versus 5.1% with anastrozole (a 20% difference; 95% CI = -37%, -3%). Safety results were consistent with the known safety profile for giredestrant. Fewer patients experienced adverse events (AEs) related to giredestrant (28%) than to anastrozole (38%), and no grade ≥3 AEs or serious adverse events were assessed as related to giredestrant. We will present the results of the primary analysis, which will include data from all enrolled patients, and will report the primary and secondary efficacy endpoints (including patients with Ki67 >20%), and updated safety. Conclusions The study will proceed to the primary analysis. We expect to see encouraging results based on the favorable interim analysis data that demonstrated the superior activity of giredestrant, an oral selective estrogen receptor antagonist and degrader, compared with anastrozole.

Citation Format: Sara A Hurvitz, Vanesa Quiroga, Yeon Hee Park, Aditya Bardia, Vanesa López-Valverde, Jutta Steinseifer, Tharu M Fernando, Gonzalo Spera, Cloris Xue, Peter A Fasching. Neoadjuvant giredestrant (GDC-9545) + palbociclib versus anastrozole + palbociclib in postmenopausal women with estrogen receptor-positive, HER2-negative, untreated early breast cancer: Primary analysis of the randomized, open-label, phase II coopERA breast cancer study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD13-06.

Abstract OT-09-06: Phase II neoadjuvant study of GDC-9545 + palbociclib (palbo) vs anastrozole (A) + palbo in postmenopausal women with estrogen receptor-positive, HER2-negative, untreated early breast cancer (ER+/HER2- eBC)

Background

Endocrine therapies (ETs) are the mainstay of ER+ BC management; however, many patients (pts) have disease relapse or develop therapeutic resistance. CDK4/6 and aromatase inhibitors decrease Ki67 expression significantly and are potent in arresting the cell cycle in the neoadjuvant eBC setting. Ki67 is a proliferation biomarker with prognostic value in ER+ BC. Efficacy of ETs relies on induction of cell cycle arrest, and during neoadjuvant treatment, Ki67 scores reflect the ability of ETs to suppress proliferation. Selective ER degraders have also shown efficacy against these tumors. The highly potent, non-steroidal, oral selective ER degrader GDC-9545 has therefore been developed as a monotherapy or in combination with CDK4/6 inhibitors for ER+ BC. Preliminary phase Ib data in postmenopausal women with metastatic BC have shown that oral 100 mg once daily (PO QD) GDC-9545 is well tolerated as a monotherapy and with palbo, with encouraging antitumor activity (clinical benefit rates: 55% without palbo/81% with palbo; clinical benefit observed in pts with prior fulvestrant treatment and in pts with detectable ESR1 mutations at enrollment) (Lim et al. ASCO 2020; abstract 1023).

We present a phase II, randomized, open-label, two-arm, neoadjuvant study of GDC-9545 vs A in a window of opportunity (WoO) phase, followed by GDC-9545 + palbo vs A + palbo in a neoadjuvant phase, for postmenopausal women with ER+/HER2- untreated eBC (NCT04436744).

Trial design

Pts are randomized 1:1 to GDC-9545 or A. The WoO phase will last 14 days; and the neoadjuvant phase, 16 weeks (4 x 28-day cycles) before surgery. GDC-9545 will be given at 30 mg PO QD; A, at 1 mg PO QD. 30 mg GDC-9545 was selected as it is well tolerated with promising anti-tumor activity (Jhaveri et al. SABCS 2019; abstract PD7-05), and no improvement in efficacy is expected at doses > 30 mg. During the neoadjuvant phase, pts will receive 4 x 28-day cycles of GDC-9545 + palbo (125 mg PO QD on days 1-21 of each cycle) or A + palbo.

Eligibility

Female pts ≥ 18 years with ECOG performance status 0-1, histologically confirmed invasive breast carcinoma, measurable disease (modified RECIST v1.1), primary tumor ≥ 1.5 cm in its longest diameter (tumor size category at presentation: cT1c [≥ 1.5 cm]-cT4a-c), and Ki67 score ≥ 5% stained nuclei.

Aims

The primary efficacy endpoint is mean relative Ki67 score change from baseline to week 2 during the WoO phase. Secondary efficacy endpoints are objective response rate and complete cell cycle arrest (CCCA) rate (proportion of patients with centrally assessed Ki67 scores ≤ 2.7% stained nuclei upon treatment at week 2) in the neoadjuvant phase. Exploratory efficacy endpoints are changes in Ki67 scores from baseline to surgery and from week 2 to surgery, CCCA rate (upon treatment at surgery or post-treatment biopsy), and pathologic complete response rate in the neoadjuvant phase. Safety and tolerability, pharmacokinetics, and biomarkers will also be assessed.

Statistical methods

Randomization is stratified by T status (cT1c-cT2 vs cT3-cT4 a-c), Ki67 score (< 20% vs ≥ 20%), and progesterone receptor status (positive vs negative). Ki67 scores will be centrally assessed and measured in percentage scores. Mean relative change at week 2 will be summarized in original percentage scales for each arm, and corresponding 95% confidence intervals will be calculated by normal approximation. Change in mean score between arms will be compared via z-test. Patients with missing central scores at baseline and/or week 2 will be excluded.

Accrual

Target enrollment is 215 patients at ~90 sites globally once the study is open for enrollment.

Contact information

For more information or to refer a patient, email global.rochegenentechtrials@roche.com or call 1-888-662-6728 (USA only).

Citation Format: Sara A Hurvitz, Peter A Fasching, Yeon Hee Park, Vanesa Quiroga, Tanja Badovinac Crnjevic, Rodrigo Fresco, Vanesa López-Valverde, Jutta Steinseifer, Chenglin Ye, Aditya Bardia. Phase II neoadjuvant study of GDC-9545 + palbociclib (palbo) vs anastrozole (A) + palbo in postmenopausal women with estrogen receptor-positive, HER2-negative, untreated early breast cancer (ER+/HER2- eBC) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr OT-09-06.

Role of Troponins I and T and N-Terminal Prohormone of Brain Natriuretic Peptide in Monitoring Cardiac Safety of Patients With Early-Stage Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer Receiving Trastuzumab: A Herceptin Adjuvant Study Cardiac Marker Substudy

Purpose Women receiving trastuzumab with chemotherapy are at risk for trastuzumab-related cardiac dysfunction (TRCD). We explored the prognostic value of cardiac markers (troponins I and T, N-terminal prohormone of brain natriuretic peptide [NT-proBNP]) to predict baseline susceptibility to develop TRCD. We examined whether development of cardiac end points or significant left ventricular ejection fraction (LVEF) drop was associated with markers' increases. Patients and Methods Cardiac marker assessments were coupled with LVEF measurements at different time points for 533 patients from the Herceptin Adjuvant (HERA) study who agreed to participate in this study. Patients with missing marker assessments were excluded, resulting in 452 evaluable patients. A primary cardiac end point was defined as symptomatic congestive heart failure of New York Heart Association class III or IV, confirmed by a cardiologist, and a significant LVEF drop, or death of definite or probable cardiac causes. A secondary cardiac end point was defined as a confirmed significant asymptomatic or mildly symptomatic LVEF drop. Results Elevated baseline troponin I (> 40 ng/L) and T (> 14 ng/L), occurring in 56 of 412 (13.6%) and 101 of 407 (24.8%) patients, respectively, were associated with an increased significant LVEF drop risk (univariate analysis: hazard ratio, 4.52; P < .001 and hazard ratio, 3.57; P < .001, respectively). Few patients had their first elevated troponin value recorded during the study (six patients for troponin I and 25 patients for troponin T). Two patients developed a primary and 31 patients a secondary cardiac end point (recovery rate of 74%, 23 of 31). For NT-proBNP, higher increases from baseline were seen in patients with significant LVEF drop. Conclusion Elevated troponin I or T before trastuzumab is associated with increased risk for TRCD. A similar conclusion for NT-proBNP could not be drawn because of the lack of a well-established elevation threshold; however, higher increases from baseline were seen in patients with TRCD compared with patients without.

Trastuzumab-Associated Cardiac Events at 8 Years of Median Follow-Up in the Herceptin Adjuvant Trial (BIG 1-01)

Purpose

To document the rate and outcome of trastuzumab-associated cardiac dysfunction in patients following 1 or 2 years of adjuvant therapy.

Patients and Methods

The Herceptin Adjuvant (HERA) trial is a three-arm, randomized trial comparing 2 years or 1 year of trastuzumab with observation in 5,102 patients with human epidermal growth factor receptor 2 (HER2) –positive early-stage breast cancer. Cardiac function was closely monitored. Eligible patients had left ventricular ejection fraction (LVEF) ≥ 55% at study entry following neoadjuvant chemotherapy with or without radiotherapy. This 8-year median follow-up analysis considered patients randomly assigned to 2 years or 1 year of trastuzumab or observation.

Results

The as-treated safety population for 2 years of trastuzumab (n = 1,673), 1 year of trastuzumab (n = 1,682), and observation (n = 1,744) is reported. Cardiac adverse events leading to discontinuation of trastuzumab occurred in 9.4% of patients in the 2-year arm and 5.2% of patients in the 1-year arm. Cardiac death, severe congestive heart failure (CHF), and confirmed significant LVEF decrease remained low in all three arms. The incidence of severe CHF (0.8%, 0.8%, and 0.0%, respectively) and confirmed significant LVEF decrease (7.2%, 4.1%, and 0.9%, respectively) was significantly higher in the 2-year and 1-year trastuzumab arms compared with the observation arm. Severe CHF was the same for 2-year and 1-year trastuzumab. Of patients with confirmed LVEF decrease receiving 2-year trastuzumab, 87.5% reached acute recovery. Of patients with confirmed LVEF decrease receiving 1-year trastuzumab, 81.2% reached acute recovery.

Conclusion

Long-term assessment at 8-year median follow-up confirms the low incidence of cardiac events for trastuzumab given sequentially after chemotherapy and radiotherapy, and cardiac events were reversible in the vast majority of patients.

Neoadjuvant and adjuvant trastuzumab in patients with HER2-positive locally advanced breast cancer (NOAH): follow-up of a randomised controlled superiority trial with a parallel HER2-negative cohort

BACKGROUND

In our randomised, controlled, phase 3 trial NeOAdjuvant Herceptin (NOAH) trial in women with HER2-positive locally advanced or inflammatory breast cancer, neoadjuvant trastuzumab significantly improved pathological complete response rate and event-free survival. We report updated results from our primary analysis to establish the long-term benefit of trastuzumab-containing neoadjuvant therapy.

METHODS

We did this multicentre, open-label, randomised trial in women with HER2-positive locally advanced or inflammatory breast cancer. Participants were randomly assigned (1:1), by computer program with a minimisation technique, to receive neoadjuvant chemotherapy alone or with 1 year of trastuzumab (concurrently with neoadjuvant chemotherapy and continued after surgery). A parallel group with HER2-negative disease was included and received neoadjuvant chemotherapy alone. Our primary endpoint was event-free survival. Analysis was by intention to treat. This study is registered at www.controlled-trials.com, ISRCTN86043495.

FINDINGS

Between June 20, 2002, and Dec 12, 2005, we enrolled 235 patients with HER2-positive disease, of whom 118 received chemotherapy alone and 117 received chemotherapy plus trastuzumab. 99 additional patients with HER2-negative disease were included in the parallel cohort. After a median follow-up of 5.4 years (IQR 3.1-6.8) the event-free-survival benefit from the addition of trastuzumab to chemotherapy was maintained in patients with HER2-positive disease. 5 year event-free survival was 58% (95% CI 48-66) in patients in the trastuzumab group and 43% (34-52) in those in the chemotherapy group; the unadjusted hazard ratio (HR) for event-free survival between the two randomised HER2-positive treatment groups was 0.64 (95% CI 0.44-0.93; two-sided log-rank p=0.016). Event-free survival was strongly associated with pathological complete remission in patients given trastuzumab. Of the 68 patients with a pathological complete response (45 with trastuzumab and 23 with chemotherapy alone), the HR for event-free survival between those with and without trastuzumab was 0.29 (95% CI 0.11-0.78). During follow-up only four cardiovascular adverse events were regarded by the investigator to be drug-related (grade 2 lymphostasis and grade 2 lymphoedema, each in one patient in the trastuzumab group, and grade 2 thrombosis and grade 2 deep vein thrombosis, each in one patient in the chemotherapy-alone group).

INTERPRETATION

These results show a sustained benefit in event-free survival from trastuzumab-containing neoadjuvant therapy followed by adjuvant trastuzumab in patients with locally advanced or inflammatory breast cancer, and provide new insight into the association between pathological complete remission and long-term outcomes in HER2-positive disease.

Follow-up results of NOAH, a randomized phase III trial evaluating neoadjuvant chemotherapy with trastuzumab (CT+H) followed by adjuvant H versus CT alone, in patients with HER2-positive locally advanced breast cancer

503

Background: The monoclonal antibody trastuzumab (H) has been shown to improve event-free survival (EFS) and pathologic complete response (pCR) in patients with HER2-positive locally advanced or inflammatory breast cancer receiving neoadjuvant chemotherapy with or without one year of trastuzumab in the primary analysis of the NOAH study (Gianni L, Lancet 2010). Updated EFS and overall survival (OS) results are now presented. Methods: In this international, multicenter, open-label, randomized phase III trial patients with locally advanced or inflammatory breast cancer were randomized 1:1 to receive CT+H followed by adjuvant H versus CT alone. A parallel cohort of 99 comparable patients with HER2-negative disease was included and treated with the same chemotherapy regimen. The neoadjuvant chemotherapy regimen included doxorubicin, paclitaxel, cyclophosphamide, methotrexate and 5-fluorouracil. The primary objective was to compare EFS defined as time from randomization to disease recurrence or progression [local, regional, distant or contralateral] or death due to any cause). Results: After a median follow up of 5.4 years, the EFS benefit with trastuzumab was confirmed. Cardiac tolerability was good despite concurrent administration of trastuzumab with doxorubicin. Two patients (2%) developed reversible symptomatic congestive heart failure and are presently alive. Conclusions: Present analysis confirms the significant EFS benefit observed in the primary analysis of the NOAH study, and shows a strong trend towards improved OS with the addition of trastuzumab to chemotherapy. pCR rate may be considered as a possible primary endpoint and early indicator of benefit in future neoadjuvant studies of HER2-targeted agents. Clinical trial information: 86043495. [Table: see text]

Long-term (8 years) assessment of trastuzumab-related cardiac events in the HERA trial

525

Background: Trastuzumab-related cardiac dysfunction may occur in patients (pts) treated with adjuvant therapy and it is mostly reversible. We report the long-term outcome of pts with cardiac dysfunction treated with adjuvant trastuzumab (T) in the Herceptin Adjuvant (HERA) trial. Methods: HERA is a three-arm, randomized trial that compared 1 year or 2 years of T with observation (Obs) in women with HER2-positive early breast cancer (EBC). Eligible pts had a left ventricular ejection fraction (LVEF) ≥ 55% at study entry (i.e. after completion of (neo)adjuvant chemotherapy with or without radiotherapy). Cardiac function was closely monitored throughout the trial. This analysis at 8-year median follow-up considers pts randomly assigned to 1 year or 2 years of T therapy or observation. Results: 5102 pts were randomized to HERA. The “as treated” safety population is considered: 2 years T (N=1,673), 1 year T (N=1,682) and Obs (N=1,744). Cardiac events leading to T discontinuation in the 1-year and 2-year arms were observed in 5.2% and 9.4% of pts, respectively. Cardiac death, severe congestive heart failure (CHF) and confirmed significant LVEF drop remained low in all three arms (Table). In the 1 year T arm, 71.4% of pts with severe CHF, and 81.2% of pts with confirmed LVEF drop recovered cardiac function (at least 2 sequential LVEF assessments > 50%). The median time to recovery was 9.7 months and 6.3 months, respectively. In the 2 years T arm, 87.5% of pts with confirmed LVEF drop recovered cardiac function and median time to recovery was 8.3 months. Conclusions: At 8-year median follow-up the incidence of cardiac events during adjuvant T remains low and these events are mostly reversible. These results confirm low cardiac events when T is given as part of the adjuvant therapy for pts with HER2-positive EBC. Clinical trial information: NCT00045032. [Table: see text]

Phosphatidyl-inositol-3-kinase alpha catalytic subunit mutation and response to neoadjuvant endocrine therapy for estrogen receptor positive breast cancer

Mutations in the alpha catalytic subunit of phosphoinositol-3-kinase (PIK3CA) occur in approximately 30% of ER positive breast cancers. We therefore sought to determine the impact of PIK3CA mutation on response to neoadjuvant endocrine therapy. Exons 9 (helical domain) and 20 (kinase domain-KD) mutations in PIK3CA were determined samples from four neoadjuvant endocrine therapy trials.Interactions with clinical, pathological, and biomarker response parameters were examined. A weak negative interaction between PIK3CA mutation status and clinical response to neoadjuvant endocrine treatment was detected(N = 235 P < or = 0.05), but not with treatment-induced changes in Ki67-based proliferation index (N = 418). Despite these findings, PIK3CA KD mutation was a favorable prognostic factor for relapse-free survival (RFS log-rank P = 0.02) in the P024 trial (N = 153). The favorable prognostic effect was maintained in a multivariable analysis(N = 125) that included the preoperative endocrine prognostic index, an approach to predicting RFS based on post neoadjuvant endocrine therapy pathological stage, ER, and Ki67 levels (HR for no PIK3CA KD mutation, 14, CI 1.9-105 P = 0.01). PIK3CA mutation status did not strongly interact with neoadjuvant endocrine therapy responsiveness in estrogen receptor-positive breast cancer. Nonetheless, as with other recent studies, a favorable interaction between PIK3CA KD mutation and prognosis was detected. The mechanism for the favorable prognostic impact of PIK3CA mutation status therefore remains unexplained.

Phase II randomized study of neoadjuvant everolimus plus letrozole compared with placebo plus letrozole in patients with estrogen receptor-positive breast cancer

PURPOSE

Cross-talk between the estrogen receptor (ER) and the phosphoinositide-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathways is a mechanism of resistance to endocrine therapy, and blockade of both pathways enhances antitumor activity in preclinical models. This study explored whether sensitivity to letrozole was enhanced with the oral mTOR inhibitor, everolimus (RAD001).

PATIENTS AND METHODS

Two hundred seventy postmenopausal women with operable ER-positive breast cancer were randomly assigned to receive 4 months of neoadjuvant treatment with letrozole (2.5 mg/day) and either everolimus (10 mg/day) or placebo. The primary end point was clinical response by palpation. Mandatory biopsies were obtained at baseline and after 2 weeks of treatment (ie, day 15). Samples were assessed for PI3K mutation status (PIK3CA) and for pharmacodynamic changes of Ki67, phospho-S6, cyclin D1, and progesterone receptor (PgR) by immunohistochemistry.

RESULTS

Response rate by clinical palpation in the everolimus arm was higher than that with letrozole alone (ie, placebo; 68.1% v 59.1%), which was statistically significant at the preplanned, one-sided, alpha = 0.1 level (P = .062). Marked reductions in progesterone receptor and cyclin D1 expression occurred in both treatment arms, and dramatic downregulation of phospho-S6 occurred only in the everolimus arm. An antiproliferative response, as defined by a reduction in Ki67 expression to natural logarithm of percentage positive Ki67 of less than 1 at day 15, occurred in 52 (57%) of 91 patients in the everolimus arm and in 25 (30%) of 82 patients in the placebo arm (P < .01). The safety profile was consistent with historical results of everolimus monotherapy; grades 3 to 4 adverse events occurred in 22.6% of patients who received everolimus and in 3.8% of patients who received placebo.

CONCLUSION

Everolimus significantly increased letrozole efficacy in neoadjuvant therapy of patients with ER-positive breast cancer.