nab-Paclitaxel plus carboplatin or gemcitabine versus gemcitabine plus carboplatin as first-line treatment of patients with triple-negative metastatic breast cancer: results from the tnAcity trial

Background

Metastatic triple-negative breast cancer (mTNBC) has a poor prognosis and aggressive clinical course. tnAcity evaluated the efficacy and safety of first-line nab-paclitaxel plus carboplatin (nab-P/C), nab-paclitaxel plus gemcitabine (nab-P/G), and gemcitabine plus carboplatin (G/C) in patients with mTNBC.

Patients and methods

Patients with pathologically confirmed mTNBC and no prior chemotherapy for metastatic BC received (1 : 1 : 1) nab-P 125 mg/m2 plus C AUC 2, nab-P 125 mg/m2 plus G 1000 mg/m2, or G 1000 mg/m2 plus C AUC 2, all on days 1, 8 q3w. Phase II primary end point: investigator-assessed progression-free survival (PFS); secondary end points included overall response rate (ORR), overall survival (OS), percentage of patients initiating cycle 6 with doublet therapy, and safety.

Results

In total, 191 patients were enrolled (nab-P/C, n = 64; nab-P/G, n = 61; G/C, n = 66). PFS was significantly longer with nab-P/C versus nab-P/G [median, 8.3 versus 5.5 months; hazard ratio (HR), 0.59 [95% CI, 0.38-0.92]; P = 0.02] or G/C (median, 8.3 versus 6.0 months; HR, 0.58 [95% CI, 0.37-0.90]; P = 0.02). OS was numerically longer with nab-P/C versus nab-P/G (median, 16.8 versus 12.1 months; HR, 0.73 [95% CI, 0.47-1.13]; P = 0.16) or G/C (median, 16.8 versus 12.6 months; HR, 0.80 [95% CI, 0.52-1.22]; P = 0.29). ORR was 73%, 39%, and 44%, respectively. In the nab-P/C, nab-P/G, and G/C groups, 64%, 56%, and 50% of patients initiated cycle 6 with a doublet. Grade ≥3 adverse events were mainly hematologic.

Conclusions

First-line nab-P/C was active in mTNBC and resulted in a significantly longer PFS and improved risk/benefit profile versus nab-P/G or G/C.

Abstract P6-17-36: Consensus and disagreement among experts for treatment of patients with HER2+ early-stage breast cancer suggests unmet need for online decision support tool

Treatment (tx) choices for HER2+ early stage breast cancer (EBC) have become increasingly complex. Clinicians and patients must decide 1) which chemotherapy and HER2-targeted agents to use, 2) the sequence of surgery and chemotherapy: either neoadjuvant (neoadj) or adjuvant (adj) tx, and 3) whether to shorten or extend maintenance HER2-targeted tx.

As tx options expand, so does the need for online decision aids. One online decision support tool was developed in 2015 to provide specific tx recommendations for pts with EBC and showed that community healthcare providers (HCPs) did not consistently align with experts for neoadj or adj tx of many pts with EBC (SABCS 2015 Abs P5-09-04).

This study includes analysis of neoadj and adj tx practice patterns of 5 breast cancer experts based on their tx recommendations for 270 unique HER2+ EBC case scenarios made for development of a 2018 online decision tool. We aim to compare these recommendations with the intended treatment of clinicians using the tool.

Results

Experts agree on neoadj tx approaches: initial surgery, no neoadj tx for pts with cT1a/b N0 tumors; neoadj tx before surgery for pts with ≥cT2 or N+ tumors. There was disparity among experts for pts with cT1c N0 disease: 3 experts recommend neoadj TCH±P and 2 recommend proceeding directly to surgery.

Experts generally recommend adj TCHP for pts with stage II N+ or higher HER2+ EBC who did not receive neoadj tx. In addition, 5/5 experts would consider extended adj tx with neratinib for these pts if HR+ and 2/5 experts would also consider neratinib if HR–.

In pts who received neoadj chemo+HER2 tx, post-surgery management depends on response to neoadj tx. For pts with pCR, 5/5 experts generally agree on continuing H+P if both were given as neoadj tx or H alone if only H given as neoadj tx for a total of 1 yr of anti-HER2 Ab tx and 2/5 experts would consider extended adj tx with neratinib for HR+ disease. For pts with residual disease, experts would recommend continuing H+P if both were given as neoadj tx and most would add P for subsequent adj tx if H alone was given to complete a total of 1 yr of anti-HER2 Ab tx (Table1). All experts would consider extended adj tx with neratinib for HR+ disease and 3/5 experts would also consider neratinib for HR– disease. None of the experts recommended less than 12 mos of adj HER2-targeted tx.

We will present analyses of cases entered into our online tool and detailed comparisons of expert and the intended treatment of clinicians using the tool.

Conclusions

Practice patterns are changing rapidly and are more complex in response to the evolving treatment landscape for HER2+ EBC. This analysis highlights several areas of expert consensus; however, disparities remain for select cases. The current tool addresses an unmet medical need for expert-led evaluation of HER2+ EBC tx choices and warrants further investigation.

Expert Recommendations: Initial Adj HER2 Ab Tx After Neodj Tx With H Alone ExpertsResponse12345pCR (HR-)HHHHHpCR (HR+)HHHHHypT1a-c N0 (HR-)H + PHH + PH + PH + PypT1a-c N0 (HR+)H + PHHH + PHypT2 N0 (HR-)H + PH + PH + PH + PH + PypT2 N0 (HR+)H + PH + PHH + PH + PypTany N+ (HR+ or HR-)H + PH + PH + PH + PH + P

Citation Format: Holmes FA, Rosenthal KM, Hurvitz S, Pegram MD, Yardley DA, Obholz KL, O'Shaughnessy J. Consensus and disagreement among experts for treatment of patients with HER2+ early-stage breast cancer suggests unmet need for online decision support tool [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-36.

Abstract P6-18-15: Ribociclib + endocrine therapy in hormone receptor-positive, HER2-negative advanced breast cancer: A pooled safety analysis

Background: In Phase III trials, ribociclib (RIB; cyclin-dependent kinase 4/6 inhibitor) + various endocrine therapy (ET) partners has demonstrated significantly prolonged progression-free survival vs placebo (PBO) + ET in patients (pts) with hormone receptor-positive (HR+), HER2-negative (HER2–) advanced breast cancer (ABC). Here we further evaluate the safety of RIB-based regimens of interest for the proposed indication (i.e. with a non-steroidal aromatase inhibitor [NSAI] or fulvestrant [FUL]) using pooled data from three Phase III trials (MONALEESA [ML]-2 [NCT01958021], -3 [NCT02422615], and -7 [NCT02278120]).

Methods: Postmenopausal pts with HR+, HER2– ABC received RIB (600 mg/day; 3-weeks-on/1-week-off) or PBO + letrozole (LET; 2.5 mg/day; ML-2 [no prior ET for ABC]) or FUL (500 mg, Days 1 and 15 of Cycle 1, then Day 1 of every cycle thereafter; ML-3; no or ≤1 prior line of ET for ABC]). Premenopausal pts (ML-7; no prior ET and ≤1 chemotherapy for ABC]) received RIB or PBO + anastrozole (1 mg/day)/LET (2.5 mg/day) + goserelin (3.6 mg every 28 days). Adverse events (AEs) were characterized per Common Terminology Criteria for Adverse Events v4.03; safety analyses included time to first event, duration of event, and rate of associated RIB/PBO discontinuations.

Results: Data for 1883 pts were pooled; 1065 pts received RIB + ET and 818 pts received PBO + ET (median exposure to study treatment: 17 and 13 months, respectively). Exposure-adjusted incidence rates for AEs of special interest were 561 and 131 per 100 pt-years in the RIB and PBO arms, respectively. The most common all-causality Grade 3/4 AEs (≥10% in any arm; RIB vs PBO) were neutropenia (59% vs 2%), leukopenia (18% vs 1%), and hypertension (13% vs 13%). A new Fridericia's corrected QT interval (QTcF) >480 ms occurred in (n/N) 52/1054 (5%) vs 11/814 (1%) pts in the RIB vs PBO arms; a new QTcF >500 ms occurred in 14/1054 (1%) vs 1/814 (<1%) pts. Median time to first event for Grade ≥2 neutropenia, elevated alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST), and QTc prolongation in the RIB arm was 2, 12, and 2 weeks, respectively; median duration of first Grade ≥2 event was 4, 4, and 2 weeks. In the RIB arm vs PBO arms, 7% vs 3% of pts discontinued study treatment due to AEs; common all-grade AEs leading to RIB/PBO discontinuation (≥2% in any arm) were elevated ALT (4% vs <1%) and elevated AST (2% vs 1%). Discontinuation due to QT prolongation occurred in 4 pts in the RIB arm and 2 in the PBO arm (both <1%). All-grade serious AEs occurred in 25% of pts in the RIB arm vs 15% of pts in the PBO arm.

Conclusions: RIB in combination with various ET partners continues to demonstrate a predictable and manageable tolerability profile across a broad population of pts with HR+, HER2– ABC.

Citation Format: Burris HA, Chan A, Im S-A, Chia S, Tripathy D, Esteva FJ, Campone M, Bardia A, Kong O, Bao W, Diaz-Padilla I, Rodriguez Lorenc K, Yardley DA. Ribociclib + endocrine therapy in hormone receptor-positive, HER2-negative advanced breast cancer: A pooled safety analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-15.

Abstract P6-18-07: Ribociclib + endocrine therapy in patients with hormone receptor-positive, HER2-negative advanced breast cancer presenting with visceral metastases: Subgroup analysis of phase III MONALEESA trials

Background: Patients (pts) with advanced breast cancer (ABC) who present with visceral metastases (mets) have a poorer prognosis vs pts with non-visceral disease. In the Phase III MONALEESA (ML) trials, ribociclib (RIB) + endocrine therapy (ET) prolonged progression-free survival (PFS) vs placebo (PBO) + ET in hormone receptor-positive (HR+), HER2-negative (HER2–) ABC. Here we show data for pts with and without visceral mets from the ML-2, -3, and -7 trials.

Methods: Data were collated from 3 trials in HR+, HER2– ABC: in ML-2 (NCT01958021; data cutoff [DCO] Jan 2/4, 2017), postmenopausal pts (no prior ET for ABC) received RIB or PBO + letrozole; in ML-3 (NCT02422615; DCO Nov 3, 2017), postmenopausal pts (no prior ET for ABC subgroup only) received RIB or PBO + fulvestrant; in ML-7 (NCT02278120; DCO Aug 20, 2017), premenopausal pts (no prior ET and ≤1 chemotherapy for ABC) received RIB or PBO + goserelin + anastrozole/letrozole. Endpoints; primary: local PFS; secondary: overall response rate (ORR), clinical benefit rate (CBR), safety.

Results: Of all 820 pts treated with RIB + ET, 484 (59%) had visceral mets (ML-2 197/334; ML-3 137/238; ML-7 150/248); of all 710 pts treated with PBO + ET, 416 (59%) had visceral mets (ML-2 196/334; ML-3 77/129; ML-7 143/247). Median PFS was prolonged for RIB vs PBO in pts with and without visceral mets (Table). ORR and CBR were also higher for RIB vs PBO in pts with and without visceral mets. The most common (≥10% of pts in any arm) Grade [G] 3 and 4 adverse events (AEs) for each trial are shown in the table; no G4 AEs occurred in ≥10% of pts in ML-3.

 Visceral metsNo visceral metsML-2 Median PFS (RIB/PBO), months (95% CI)24.9 (22.2–30.9)/13.4 (12.7–16.5)25.3 (22.2–NR)/18.2 (15.0–24.6)Hazard ratio (95% CI)0.538 (0.408–0.709)0.634 (0.448–0.897) ORR (RIB/PBO),* %48/3735/17 CBR (RIB/PBO),† %79/7282/75 Most common (≥10% in any arm) G3 AEs (RIB/PBO), %Neutropenia56/147/1Leukopenia19/121/<1Hypertension11/1115/15 Most common (≥10% in any arm) G4 AEs (RIB/PBO), %Neutropenia10/09/0 ML-3 Median PFS (RIB/PBO), months (95% CI)NR (19.1–NR)/16.5 (9.0–NR)NR (NR–NR)/21.9 (14.8–NR)Hazard ratio (95% CI)0.610 (0.403–0.926)0.521 (0.295–0.921) ORR (RIB/PBO),* %46/2931/21 CBR (RIB/PBO),† %74/6075/81 Most common (≥10% in any arm) G3 AEs (RIB/PBO), %Neutropenia50/045/0Leukopenia12/010/0Increased ALT6/012/0 ML-7 Median PFS (RIB/PBO), months (95% CI)23.8 (14.8–NR)/10.4 (7.2–12.9)27.5 (NR–NR)/19.3 (16.5–NR)Hazard ratio (95% CI)0.507 (0.367–0.700)0.609 (0.377–0.984) ORR (RIB/PBO),* %45/3630/19 CBR (RIB/PBO),† %79/5783/81 Most common (≥10% in any arm) G3 AEs (RIB/PBO), %Neutropenia54/356/4Leukopenia14/116/1 Most common (≥10% in any arm) G4 AEs (RIB/PBO), %Neutropenia11/<19/0CI, confidence interval; NR, not reached. *ORR = complete response + partial response; †CBR = complete response + partial response + (stable disease + non-complete response/non-progressive disease ≥24 weeks).

Conclusions: Although the presence of visceral mets is associated with a poorer prognosis, RIB + ET is an effective and well-tolerated treatment option for pts with HR+, HER2– ABC irrespective of the presence of visceral mets.

Citation Format: Yardley DA, Chan A, Nusch A, Sonke GS, Yap Y-S, Bachelot T, Esteva FJ, Slamon DJ, Burris HA, Gaur A, Kong O, Diaz-Padilla I, Rodriguez Lorenc K, Wheatley-Price P. Ribociclib + endocrine therapy in patients with hormone receptor-positive, HER2-negative advanced breast cancer presenting with visceral metastases: Subgroup analysis of phase III MONALEESA trials [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-07.

Abstract OT2-06-04: MORPHEUS: A phase Ib/II trial platform evaluating the safety and efficacy of multiple cancer immunotherapy combinations in patients with hormone receptor–positive and triple-negative breast cancer

Background:

Cancer immunotherapy (CIT) has significantly improved overall survival across multiple tumor types, but only subsets of patients experience durable response with single-agent CIT. Combinations of CIT with targeted therapy or chemotherapy may be needed in order to target multiple cancer immune escape mechanisms simultaneously, thus providing personalized treatment options that extend clinical benefit to more patients. The MORPHEUS platform includes multiple phase Ib/II trials designed to identify early signals of safety and activity of CIT combinations. Using a randomized trial design, multiple CIT combination arms are compared with a single standard-of-care control arm. These trials have the flexibility to open new treatment arms with novel CIT combinations as they become available and to close arms that show minimal activity or unacceptable toxicity. Here we describe MORPHEUS trials in patients with metastatic or unresectable locally advanced hormone receptor–positive (HR+BC) or triple-negative breast cancer (TNBC), 2 patient populations in need of more treatment options.

Trial design:

MORPHEUS-HR+BC (NCT03280563) will enroll patients with metastatic or unresectable locally advanced HR+BC who have progressed during or after first-line treatment with a cyclin-dependent kinase (CDK) 4/6 inhibitor and whose tumors do not express human epidermal growth factor 2 (HER2). MORPHEUS-TNBC (NCT03424005) will enroll patients with metastatic or unresectable locally advanced TNBC who have progressed during or after first-line treatment with chemotherapy. For both studies, key inclusion criteria include Eastern Cooperative Oncology Group performance status of 0-1 (stage 1) or 0-2 (stage 2) and measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. Key exclusion criteria include prior treatment with T-cell co-stimulating or immune checkpoint blockade therapies, and symptomatic, untreated, or actively progressing central nervous system metastases. Patients in both trials will be randomized to one of the CIT atezolizumab combination arms or a control arm (up to 5 arms in HR+BC and up to 6 arms in TNBC). Patients experiencing loss of clinical benefit or unacceptable toxicity in stage 1 may be eligible to switch to a different CIT atezolizumab combination arm in stage 2. Primary endpoints are safety measures and investigator-assessed objective response rate per RECIST v1.1. Progression-free survival, overall survival, duration of response, clinical benefit rate (HR+BC) or disease control rate (TNBC) are among the secondary endpoints. Exploratory biomarkers will also be examined.

Citation Format: Yardley DA, Abu-Khalaf M, Boni V, Brufsky A, Emens LA, Gutierrez M, Hurvitz S, Im S-A, Loi S, McCune SL, Schmid P, O'Hear C, Zhang X, Vidal GA. MORPHEUS: A phase Ib/II trial platform evaluating the safety and efficacy of multiple cancer immunotherapy combinations in patients with hormone receptor–positive and triple-negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-06-04.

Abstract PD5-11: Not presented

This abstract was not presented at the symposium.

Abstract OT3-05-06: EarLEE-2: A phase 3 study of ribociclib + endocrine therapy (ET) for adjuvant treatment of patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–), intermediate-risk, early breast cancer (EBC)

Background: Adjuvant ET with or without chemotherapy reduces the risk for recurrence of HR+, HER2– EBC. However, recurrence is still common, especially in patients with adverse clinical and pathologic features. In the phase 3 MONALEESA-2 trial, the cyclin-dependent kinase 4/6 inhibitor ribociclib (LEE011), in combination with letrozole, prolonged progression-free survival versus letrozole plus placebo in postmenopausal women with HR+, HER2– advanced breast cancer and no prior therapy for advanced disease (HR = 0.56, 95% CI, 0.43-0.72; P = 3.29×10−6; Hortobagyi et al. N Engl J Med. 2016). EarLEE-2 is investigating the efficacy and safety of ribociclib with ET versus placebo with ET as adjuvant treatment in patients with intermediate-risk EBC.

Trial design: In this double-blind, placebo-controlled, phase 3 adjuvant trial, ˜4,000 women and men with fully resected, intermediate-risk, HR+, HER2– EBC (defined as AJCC 8th ed. Prognostic Stage Group II) are being randomized 1:1 to oral ribociclib (600 mg/day, 3 weeks on/1 week off for ˜24 months) plus ET or to placebo plus ET. Adjuvant ET may include tamoxifen, letrozole, anastrozole, or exemestane for ≥ 60 months with ovarian suppression for premenopausal women at the discretion of the investigator. Adjuvant ET in men will be tamoxifen only. Neoadjuvant therapy is not permitted. Randomization is stratified by menopausal status (men and premenopausal women vs postmenopausal women), prior adjuvant chemotherapy (yes vs no), Prognostic Stage Group (IIA vs IIB), and geographic region (North America/Europe/Australia vs rest of the world). Eligible patients must have tumor tissue from the surgical specimen, adequate bone marrow and organ functions, normal serum electrolytes, QTc interval < 450 msec, and completed and recovered from acute toxicities of adjuvant radiotherapy and/or chemotherapy. The primary endpoint is invasive disease-free survival (per STEEP system; Hudis et al. J Clin Oncol. 2007). Secondary endpoints include recurrence-free survival, distant disease-free survival, overall survival, quality of life, and safety. Global recruitment to EarLEE-2 is ongoing. NCT03081234

Citation Format: O'Shaughnessy J, Alba E, Bardia A, Dent S, Dieras V, Hortobagyi G, Im S-A, Montemurro F, Untch M, Yardley DA, Chakravartty A, Germa C, Miller M, Slamon D. EarLEE-2: A phase 3 study of ribociclib + endocrine therapy (ET) for adjuvant treatment of patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–), intermediate-risk, early breast cancer (EBC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT3-05-06.

Abstract PD4-06: First-line ribociclib + letrozole in hormone receptor-positive, HER2-negative advanced breast cancer: Efficacy by baseline circulating tumor DNA alterations in MONALEESA-2

Background: The addition of first-line ribociclib (RIB; cyclin-dependent kinase 4/6 inhibitor) to letrozole (LET) significantly improved progression-free survival (PFS) compared with placebo (PBO) + LET in patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (ABC) in the Phase III MONALEESA-2 study. Identifying biomarkers that predict response to treatment remains a key challenge in pts with HR+ ABC. Here we analyze results from MONALEESA-2 by molecular alterations detected in circulating tumor DNA (ctDNA) at baseline, including PIK3CA mutations and other alterations considered to be important in HR+ ABC.

Methods: Postmenopausal women (N=668) with HR+, HER2– ABC who had not received any prior therapy for ABC were randomized 1:1 to RIB (600 mg/day; 3-weeks-on/1-week-off) + LET (2.5 mg/day; continuous) or PBO + LET. The primary endpoint was PFS. Biomarker analysis of the ctDNA mutation profile was an exploratory endpoint. Plasma samples for ctDNA analysis were collected at baseline and end of treatment. ctDNA was analyzed using next-generation sequencing with a targeted panel of ˜550 genes.

Results: Baseline ctDNA was successfully sequenced in 494 pts (RIB + LET: n=212; PBO + LET: n=215); 67 (14%) of 494 pts were removed from the analysis due to limited tumor DNA in circulation. 427 (86%) pts had ≥1 alteration, including 1,573 mutations, 513 short insertions/deletions, 166 amplifications, and 8 translocations. Alterations (frequency) were commonly observed in the following genes: PIK3CA (33%), TP53 (12%), ZNF703/FGFR1 (5%), and ESR1 (4%), and in genes involved in receptor tyrosine kinase (RTK) signaling (12%). RIB + LET treatment benefit was consistent in pts with wild-type (WT) and altered PIK3CA, and in pts with WT and altered TP53 (Table). RIB + LET improved PFS regardless of RTK or ZNF703/FGFR1 alterations. However, there was a weak trend for increased benefit in pts with WT vs altered RTK genes and in pts with WT vs altered ZNF703/FGFR1 genes. These results should be interpreted with caution due to the small number of pts with these alterations. There were too few ESR1 alterations for firm conclusions to be drawn.

 Events, n/NMedian PFS, months Gene(s)RIB + LETPBO + LETRIB + LETPBO + LETHazard ratio (95% confidence interval)PIK3CAWT54/14393/14229.614.70.44 (0.31–0.62)Altered40/6955/7319.212.70.53 (0.35–0.81)TP53WT72/180129/19427.614.70.44 (0.33–0.59)Altered22/3219/2110.25.50.43 (0.23–0.83)ZNF703/FGFR1WT88/202139/20524.814.60.47 (0.36–0.62)Altered6/109/1010.611.40.73 (0.23–2.29)RTKWT81/189128/18724.814.40.46 (0.35–0.61)Altered13/2320/2821.311.40.72 (0.34–1.53)

Conclusions: Consistent RIB + LET treatment benefit was observed compared with PBO + LET, irrespective of the status of baseline ctDNA biomarkers.

Citation Format: Hortobagyi GN, Stemmer S, Campone M, Sonke GS, Arteaga CL, Paluch-Shimon S, Petrakova K, Villanueva C, Nusch A, Grischke E-M, Chan A, Jakobsen E, Marschner N, Hart LL, Alba E, Ohnstand HO, Blau S, Yardley DA, Solovieff N, Su F, Germa C, Yap Y-S. First-line ribociclib + letrozole in hormone receptor-positive, HER2-negative advanced breast cancer: Efficacy by baseline circulating tumor DNA alterations in MONALEESA-2 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD4-06.

Abstract P4-22-04: A randomized, double-blind, phase 2 study of ruxolitinib (RUX) or placebo (PBO) in combination with capecitabine (CAPE) in patients (pts) with advanced HER2-negative breast cancer (ABC) and elevated C-reactive protein (CRP), a marker of systemic inflammation

Background: Systemic inflammation is associated with poor prognosis in pts with ABC. The JAK/STAT pathway is a key regulator of inflammatory signaling, associated with tumorigenesis, cell survival, and progression. We evaluated the efficacy and safety of RUX, a JAK1/JAK2 inhibitor, plus CAPE in pts with HER2-negative ABC and high systemic inflammation defined by the modified Glasgow Prognostic Score (mGPS). Methods: In this double-blind phase 2 trial, pts were randomized 1:1 to 21 day cycles of RUX+CAPE or PBO+CAPE: RUX 15 mg or PBO PO BID for 21 d; CAPE 1000 mg/m2 PO BID for 14 d. Key inclusion criteria were systemic inflammation by mGPS of 1 or 2 (ie, CRP >10 mg/L), ECOG performance status ≤2, ≤2 prior chemotherapy regimens, and no prior CAPE. The primary endpoint was overall survival (OS); key secondary endpoints were progression-free survival (PFS), objective response rate (ORR; complete [CR] + partial response [PR]) per RECIST v1.1, clinical benefit rate (CBR; CR + PR + stable disease for ≥6 mo), duration of response, and safety. Treatment differences in OS and PFS were analyzed by the log-rank test; HRs and CIs were analyzed by the Cox proportional hazards model. Results: Baseline characteristics were similar between pts randomized to RUX+CAPE (n=76) vs PBO+CAPE (n=73): mGPS status (1, 82.9% vs 83.6%), hormone receptor (HR) status (positive, 67.1% vs 63.0%), and number of prior chemotherapy regimens for ABC (0, 50.0% vs 50.7%; 1, 38.2% vs 34.2%; 2, 9.2% vs 13.7%). Median treatment durations were 85 d with RUX in the RUX+CAPE group and 65 d with PBO in the PBO+CAPE group. Median OS was 11.2 mo with RUX+CAPE vs 10.9 mo with PBO+CAPE (HR, 0.932; 95% CI, 0.59–1.46; P=0.762). Median OS was 6.1 mo with RUX+CAPE vs 5.5 mo with PBO+CAPE in HR-negative pts and 11.7 mo and 12.2 mo in HR-positive pts. Median PFS was 4.5 mo with RUX+CAPE and 2.5 mo with PBO+CAPE (HR, 0.737; 95% CI, 0.49–1.12; P=0.151). Median PFS was 2.1 mo with RUX+CAPE vs 2.2 mo with PBO+CAPE in HR-negative pts and 6.1 mo and 4.1 mo in HR-positive pts. ORRs were 28.9% and 13.7% (P=0.024) in the RUX+CAPE and PBO+CAPE arms, respectively. The CBRs were 13.2% and 6.8%, respectively (P=0.278). Worsening of hematologic toxicity was higher and rates of grade 3/4 palmar-plantar erythrodysethesia (PPE) were lower (1.4% vs 12.7%, respectively) with RUX+CAPE (Table).

Safety RUX+CAPE (n=71)PBO+CAPE (n=71)%All-GradeGrade 3/4All-GradeGrade 3/4Nonhematologic Adverse Event*Fatigue56.35.643.74.2Nausea54.98.549.35.6Diarrhea47.98.526.82.8PPE46.51.438.012.7Vomiting38.05.629.64.2Hypokalemia15.58.57.02.8Worsening of Hematologic Toxicity†Anemia80.323.956.37.0Lymphopenia40.815.545.112.7Neutropenia39.411.322.52.8Thrombocytopenia39.411.315.51.4*Most common all-grade (≥35%) or grade 3/4 (≥5%) events in the RUX+CAPE arm (safety group). †Laboratory abnormalities.

Conclusion: These data support the prognostic capabilities of the mGPS. The addition of RUX to CAPE for pts with ABC and high systemic inflammation was associated with an improved ORR compared with PBO+CAPE, but did not improve OS or PFS.

Citation Format: O'Shaughnessy J, DeMichele A, Ma C, Richards P, Yardley DA, Wright G, Kalinsky K, Steis R, Diab S, Kennealey G, Geschwindt R, Jiang W, Rugo H. A randomized, double-blind, phase 2 study of ruxolitinib (RUX) or placebo (PBO) in combination with capecitabine (CAPE) in patients (pts) with advanced HER2-negative breast cancer (ABC) and elevated C-reactive protein (CRP), a marker of systemic inflammation [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-04.

Abstract P5-08-27: Treatment patterns and clinical outcomes in patients with hormone receptor (HR)+ HER2+ metastatic breast cancer and low vs high levels of HR positivity from the SystHERs Registry

Introduction In 2010, the cutoff for HR positivity in breast cancer was established as ≥1% of cells staining HR+, previously having varied from 1% to 10%. The impact of this change on treatment patterns and outcomes is poorly understood. SystHERs is a prospective, observational cohort registry of patients (pts) with HER2+ metastatic breast cancer (MBC) that commenced enrollment in 2012. To our knowledge, SystHERs is the largest registry to collect and analyze data for the HER2+ subgroup. We report baseline characteristics, treatment patterns, and early outcomes by %HR+ (1–9% vs 10–100%).

Methods SystHERs enrolled pts aged ≥18 years and within 6 months of HER2+ MBC diagnosis. For pts with locally-determined HR+ disease, defined as HR+ in primary or metastatic tissue, %HR+ is the highest percentage of ER+ or PR+ tissue in early breast cancer or MBC. The percentage of ER+ or PR+ cells was not reported for pts considered HR– by the investigator. Median overall survival (OS; Kaplan–Meier) and hazard ratios (Cox regression) were estimated.

Results As of Feb 1, 2016, data were available for 872 eligible pts with known HR status, of whom 608 (70%) had HR+ disease. Of the 608 pts, 53 (9%) had 1–9%HR+ and 496 (82%) had 10–100%HR+; %HR+ was not reported for 59 pts. Baseline characteristics were similar between %HR+ subgroups (Table 1).

As shown in Table 2, the 1–9%HR+ subgroup was less likely to receive first-line hormonal therapy (26%) than the 10–100%HR+ subgroup (56%). 87% and 79% of pts received chemotherapy, respectively.

Median time from MBC diagnosis was 16.5 months (range, 0.4–49.4 months). Median OS was not reached at the data cutoff. The number of deaths was 13 (25%) in the 1–9%HR+ subgroup, and 68 (14%) in the 10–100%HR+ subgroup (log-rank P=0.025). The OS hazard ratio (0.514, 95% CI 0.283–0.931) favored the 10–100%HR+ subgroup. OS did not differ significantly between pts with 1–9%HR+ vs HR– disease (log-rank P=0.582, hazard ratio 1.185, 95% CI 0.647–2.169).

Table 1. Baseline characteristics 1-9%HR+ (n=53)10-100%HR+ (n=496)HR– (n=264)Age at MBC diagnosis, median yrs (range)54 (30–86)57 (21–86)55 (28–88)Race, %   White838372Black151320Premenopausal, %282522ECOG performance status, %   04654441463942≥2878MBC diagnosis type, %   De novo404958Recurrent605142Visceral, %*686275*Non-hepatic abdominal, ascites, CNS, liver, lung, or pleural effusion sites of metastasis

Table 2. First-line treatment 1-9%HR+ (n=53)10-100%HR+ (n=496)HR– (n=264)HER2-targeted therapy, %969391Chemotherapy, %877989Hormonal therapy, %26564

Conclusions These preliminary observational data suggest potential differences in treatment patterns and survival outcomes in low vs moderate/high HR+ expressers, with the former being less likely to receive hormonal therapy (26% vs 56%). Furthermore, low HR positivity was associated with poorer OS and was similar to OS observed in pts with HR– disease.

Citation Format: Jahanzeb M, Tripathy D, Rugo H, Swain S, Kaufman PA, Mayer M, Hurvitz S, O'Shaughnessy J, Mason G, Yardley DA, Brufsky A, Chu L, Antao V, Beattie M, Yoo B, Cobleigh M. Treatment patterns and clinical outcomes in patients with hormone receptor (HR)+ HER2+ metastatic breast cancer and low vs high levels of HR positivity from the SystHERs Registry [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-08-27.

Abstract OT2-01-05: TRINITI-1: Ribociclib + everolimus (EVE) + exemestane (EXE) triplet combination in men or postmenopausal women with HR+, HER2– advanced breast cancer (ABC) following progression on a cyclin-dependent kinase (CDK) 4/6 inhibitor

Background: There is extensive crosstalk between the cyclin D–CDK4/6–inhibitor of CDK4–retinoblastoma and phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathways at the G1/S cell-cycle checkpoint. Both pathways are frequently dysregulated in hormone receptor-positive (HR+) breast cancer and have been associated with endocrine therapy (ET) resistance. CDK4/6 and PI3K/mTOR inhibitors have demonstrated clinical activity in combination with ET. Although CDK4/6 inhibitors combined with ET significantly improve progression-free survival (PFS) in ABC, disease progression eventually occurs, highlighting the need for effective treatment options following doublet therapy. Ribociclib (LEE011; CDK4/6 inhibitor; 3-weeks-on/1-week-off) + EVE (mTOR inhibitor) + EXE triplet therapy has shown preliminary clinical activity in heavily pretreated HR+, human epidermal growth factor receptor 2-negative (HER2–) ABC including patients (pts) with prior exposure to CDK4/6 inhibitors, suggesting this combination may restore sensitivity to CDK4/6 inhibitor-based therapy.

Trial design and objectives: TRINITI-1 (NCT02732119) is a US-based, phase I/II, single arm, open-label study of ribociclib (continuous daily dosing) + EVE (2.5 mg/day) + EXE (25 mg/day) in men and postmenopausal women with HR+, HER2– ABC refractory to ≥1 line of ET. Phase I dose escalation consists of 2 ribociclib dose-level cohorts (250 and 300 mg/day), followed by a Simon Two-Stage phase II trial in pts with disease progression on prior CDK4/6 inhibitor-based therapy. No more than 3 lines of therapy for ABC, including ≤1 prior chemotherapy regimen, are permitted. Previous EXE treatment of >28 days for metastatic disease, prior mTOR inhibitors, and progression on >1 CDK4/6 inhibitor are prohibited. All pts in phase II must have progressed on a CDK4/6 inhibitor as the last regimen before study entry. Additional eligibility criteria include measurable disease or lytic/mixed bone lesions and Eastern Cooperative Oncology Group performance status of ≤1. Exclusion criteria include visceral crisis, unstable CNS metastases, and clinically significant heart disease. Phase I primary objective: maximum tolerated dose and/or recommended phase II dose of the triplet combination. Phase II primary objective: clinical benefit rate (CBR) at 24 weeks (0.1 significance level, 80% power to test CBR ≤15% against CBR ≥30%) with centrally-assessed PFS as a key secondary objective. Other secondary objectives include preliminary antitumor activity (phase I), safety and pharmacokinetics (phase I/II), and overall response rate, overall survival, and duration of overall response (phase II). Tumor assessments (RECIST v1.1) will be performed every 8 weeks for the first 12 months, and every 12 weeks thereafter until disease progression. Exploratory analyses include biomarkers potentially predictive of response and mechanisms of resistance.

Target accrual: Approximately 52 pts at ∼30 sites; 3–6 pts per cohort in phase I, an initial 19 in phase II with another 20 enrolled upon demonstration of clinical benefit in ≥4 pts.

Citation Format: Bardia A, Hurvitz S, Yardley DA, Zelnak A, DeMichele A, Clark AS, Warsi G, Small T, Tucci C, Moulder S. TRINITI-1: Ribociclib + everolimus (EVE) + exemestane (EXE) triplet combination in men or postmenopausal women with HR+, HER2– advanced breast cancer (ABC) following progression on a cyclin-dependent kinase (CDK) 4/6 inhibitor [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-05.

Abstract P2-08-01: Results from a randomized placebo-controlled phase 2 trial evaluating exemestane ± enzalutamide in patients with hormone receptor–positive breast cancer

This abstract was withdrawn by the authors.

Abstract P4-22-09: A phase 2 open label study of everolimus in combination with endocrine therapy in resistant hormone receptor-positive HER2-negative advanced breast cancer

Background: Therapies targeting estrogen receptor (ER) signaling are standard for patients (pts) with hormone receptor positive (HR+) (ER and/or progesterone receptor [PR] positive) metastatic breast cancer (MBC). Dysregulation of the mammalian target of rapamycin (mTOR) pathway has been associated with endocrine therapy (ET) resistance. BOLERO-2 demonstrated that the addition of the mTOR inhibitor, everolimus (EVE), to exemestane doubled the PFS in HR+ HER2- MBC pts who previously progressed on nonsteroidal aromatase inhibitor therapy.The premise of this phase 2 trial in HR+ MBC is that the addition of EVE to the last ET on which the disease progressed may restore sensitivity to ET and extend the benefit of the anti-estrogen therapy.

Methods: Pts ≥18 yrs with HR+, HER2- unresectable, locally recurrent, or MBC refractory to ET in either the adjuvant or advanced/metastatic setting. 0-1 chemotherapy (chemo) regimens for MBC were permitted. Post-/ pre-/peri-menopausal women were eligible with ovarian function suppression permitted. Additional eligibility requirements include: no prior mTOR inhibitor therapy, measurable or evaluable disease, ECOG ≤2, adequate bone marrow and organ function. EVE (10 mg PO daily) was administered on a 4-wk cycle in combination with the same dose and schedule of the last ET to which their disease became resistant. Disease assessments were performed every 2 cycles and treatment continued until disease progression or unacceptable toxicity. Blood samples and archival tumor were collected respectively for the VeriStrat Assay and for the Foundation One molecular profiling platform.

Results: 48 pts were enrolled; data from 26 pts is presented. Median age 63.5 yrs (range, 36-81) with 46% ≥ 65 yrs. 14 (54%) pts had received chemo in the adjuvant setting, 9 pts (35%) received chemo for MBC, and 4 pts (15%) received chemo in both settings. All pts had at least 1 prior hormonal therapy; 9 pts received ≥ 3 hormonal agents. EVE was combined with tamoxifen (27%), AIs (61%), and fulvestrant (12%). Median time on treatment was 18.6 wks (range 1-48.9 weeks). 5 pts (19%) remain on treatment and 21 (81%) have discontinued therapy due to: disease progression - 17, toxicity -2, and other causes - 2. 23 pts were evaluable for response. 1 pt on fulvestrant plus EVE had a PR and 18 pts (78%) had SD as best response, with SD > 6 mos in 7 pts, for a clinical benefit rate (CR+PR+ SD ≥ 6 months) of 35%. With a median follow up of 11 mos (range 2-16 mos), the median PFS was 6.6 months (range 3.6-9.4); the median OS has not been reached. Treatment-related adverse events consisted mostly of stomatitis, rash and fatigue with few G3 events: stomatitis 3 pts, rash 2 pts, and 1 each of fatigue, edema, and neutropenia. G1 pneumonitis was present in 2 pts. There were no G4 events or treatment related deaths.

Conclusions: In HR+ HER2- advanced/MBC patients who progressed on prior ET, the addition of EVE to the ET to which their disease became resistant, resulted in 1 PR and 7 pts with SD > 6 mos. The results of the full study population will be presented. Modulation of the mTOR/AKT/PI3K pathway with EVE may extend the benefit of ET, even after tumor progression on ET alone.

Citation Format: Yardley DA, Blakely L, Hemphill B, Joseph M, Liggett W, Daniel B, Castrellon A, Shastry M, Finney L, DeBusk L, Hainsworth JD, Burris III HA. A phase 2 open label study of everolimus in combination with endocrine therapy in resistant hormone receptor-positive HER2-negative advanced breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-09.

Abstract P6-11-03: A phase 2 open-label study of lucitanib in patients (pts) with FGF aberrant metastatic breast cancer (MBC)

BACKGROUND: Lucitanib is a potent, oral antiangiogenic tyrosine kinase inhibitor of Vascular Endothelial Growth Factor Receptors 1-3 (VEGFR1-3), Platelet-Derived Growth Factor Receptors alpha and beta (PDGFRα/β), and Fibroblast Growth Factor Receptors 1-3 (FGFR1-3). FGF aberrancies (amplification of FGFR1,or 11q[amplicon containing FGF ligands 3, 4, and 19]), are genomic alterations observed in over 20% of breast cancer pts and promote cancer proliferation and survival.

METHODS: MBC pts who had received at least 1 metastatic line of therapy were randomized 1:1 to 10 or 15 mg QD of lucitanib. Stratification was based on local assessment of FGF aberrancy; pts with both FGFR1 and 11q-amplified tumors were stratified as FGFR1 amplified. Central confirmation of FGFR1 or 11q amplification was done using Abbott FISH probes (FGFR1 or 11q copy number ≥ 6 and a ratio of FGFR1 or 11q to centromere ≥ 2). Investigator-assessed progression-free survival (PFS) was the primary endpoint. Secondary endpoints included objective response rate (ORR) per RECIST 1.1, disease control rate (DCR), duration of response (DR), and incidence of treatment-emergent adverse events (TEAE).

RESULTS: Enrollment completed in 3/2016; 178 pts that received at least 1 dose of lucitanib are included in this analysis (baseline characteristics in Table 1). Due to grade 3 hypertension in the 15 mg group (46% vs 37% in 10 mg group), enrollment to the 15 mg group was halted. Overall, most pts (97%) experienced at least 1 TEAE, with the most frequently (≥ 30%) occurring events being hypertension (73%), fatigue (48%), nausea (43%), hypothyroidism (40%), and headache (33%). Grade ≥ 3 TEAEs occurred in 66% of pts, with hypertension as the most frequent event (40%) followed by proteinuria and hyponatremia (both 6%). AEs were manageable with dose interruption or reduction, with approximately 8% of pts ending treatment due to an AE. Current median PFS is 3.5 mos (95% CI 2.8-4.6; range 0.62-12.95) and 2.6 mos (95% CI 1.8-2.9; range 0.82-18.87) respectively for the 10 mg and 15 mg treatment groups. No differences in clinical activity were observed by treatment group, FGF aberrancy, hormone receptor or HER2 status. Of the 168 evaluable pts, confirmed ORR was 3%; overall DCR was 27% (32% for pts in the 10 mg group compared to 20% for the 15 mg group); overall mean (standard deviation) DR of 3.3 (1.8) mos.

Baseline Characteristics 10 mg QD15 mg QD N=109N=69Age (years)Median5653Range27-8227-80SexFemale109 (100%)67 (97%)Male02 (3%)ECOG PSmissing5 (5%)2 (3%)051 (47%)30 (43%)153 (49%)37 (54%)Number of prior anticancer therapies in the metastatic setting> 332 (29%)21 (30%)3-648 (44%)32 (46%)> 629 (27%)16 (23%)Endocrine/HER2 statusmissing7 (6%)1 (1%)ER+ or PR+74 (68%)50 (73%)HER2+12 (11%)7 (10%)TNBC16 (15%)11 (16%)FGFR aberrancyFGFR1 amplified54 (49%)29 (42%)11q amplified31 (28%)24 (35%)FGFR1 and 11q amplified13 (12%)9 (13%)FGFR1 and 11q non-amplified11 (10%)7 (10%)

CONCLUSION: At 10 mg QD, lucitanib has modest activity with manageable toxicity in this heavily pretreated pt population. Future clinical development for lucitanib may focus on alternative biomarkers to identify sensitive tumors and rational combinations with other anti-cancer drugs.

Citation Format: Mayer IA, Arteaga CL, Nanda R, Miller KD, Jhaveri K, Brufsky AM, Rugo H, Yardley DA, Vahdat LT, Sadeghi S, Audeh MW, Rolfe L, Litten J, Knox A, Raponi M, Tankersley C, Isaacson J, Wride K, Morganstern DE, Vogel C, Connolly RM, Gradishar WJ, Patel R, Pusztai L, Abu-Khalaf M. A phase 2 open-label study of lucitanib in patients (pts) with FGF aberrant metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-11-03.

Abstract P1-01-16: Circulating tumor cells (CTCs) biomarker evaluation from patients with metastatic breast cancer (MBC) utilizing the TargetSelectorTM platform

Background: Circulating blood biomarkers represent the promise of non-invasive, real-time surrogates for tumor tissue-based biomarkers as well as afford monitoring opportunities over the course of therapy as tumors evolve and acquire resistance to treatment. Circulating tumor cells (CTCs) are cells that disseminate from tumors and can be identified in peripheral blood. CellSearch® is an FDA approved methodology for detecting and enriching this rare CTC population. The prognostic value of CTCs has been established, however the potential to characterize biomarkers on CTCs to inform treatment decisions remains an active area of investigation. Among the emerging platforms for detection and characterization of CTCs is the TargetSelectorTM system. While CellSearch® is limited to capture and detection of epithelial derived CTCs based on EpCAM and cytokeratin (CK) respectively, Biocept's TargetSelectorTM platform utilizes a novel microfluidic system for CTC enrichment based on an antibody capture cocktail that allows for enumeration of CTCs with variable phenotypes (including CK- CTCs). The CTCs are captured in transparent microfluidic chambers and cells can be viewed in situ by fluorescence microscopy and analyzed via immunocytochemistry (ICC), fluorescence in situ hybridization (FISH) and PCR analyses.

Methods: Sixty-one patients with metastatic breast cancer consented and provided blood for utilization in the TargetSelectorTM platform. Based on the molecular analysis of tissue biopsies, 92% of these patients had ER+ breast tumors. Biomarker expression on captured CTCs was determined by ICC for ER and by FISH for HER2. Concordance between these results and biomarker expression on archival tumor tissue from these patients was calculated.

Results: CTCs were detected in 60 of 61 patient blood samples (range 2–4471); 68% had both CK+ and CK- CTCs, and 32% had only CK- CTCs. None had only CK+ CTCs. Of those with CK+ CTCs, concordance for ER expression between the tissue and blood analyses was 85% (35/41). Concordance was much lower for patients with only CK- CTCs (32%, 6/19). Concordance for HER2 amplification in CK+ patients was 93% (38/41), and 68% (13/19) in CK- patients. For this study, the liquid biopsy was obtained over an extended period of time from when solid tumor ER and HER2 assessments were obtained; this latency period may have influenced concordance levels. For HER2, there was a significantly longer time interval between biopsies for non-concordant than for concordant pairs of samples (58.1 ± 19.7 vs. 30.9 ± 4.3 months) regardless of the CK status. No such difference was seen for the ER analysis.

Conclusions: In this exploratory analysis of 61 patients with MBC, we observed a high rate of detectable CTCs as well as CTC concordance for ER (85%) and HER2 amplification (93%) for patients who had CK+ CTCs. Concordance was less if patients only had CK- CTCs. This may be attributable to heterogeneity in the breast cancer phenotypes associated with these CK- CTCs in addition to inherent issues with testing cell surface markers in this population of cells. The variable latency between the between the collection of tissue and blood samples for these analyses may account for the discrepancies observed.

Citation Format: Hamilton EP, Yardley DA, Burris III HA, Shastry M, Huynh L, Bhikha L, Singh VM. Circulating tumor cells (CTCs) biomarker evaluation from patients with metastatic breast cancer (MBC) utilizing the TargetSelectorTM platform [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-01-16.

Abstract P1-14-06: A phase II randomized study with eribulin/cyclophosphamide (ErC) and docetaxel/cyclophosphamide (TC) as neoadjuvant therapy in HER2-negative breast cancer- Final analysis of primary endpoint and correlative analysis results

Background: Eribulin mesylate (Er) is a non-taxane inhibitor of microtubule growth that results in G2-M cell cycle arrest, disruption of normal mitotic spindles and apoptosis. Er demonstrated an overall survival (OS) but not progression free survival (PFS) advantage in anthracycline and taxane refractory breast cancer pts. This OS rather than PFS benefit has been attributed to Er's potential to suppress new metastases through its effects on the epithelial mesenchymal transition (EMT) pathway, even in the absence of an effect on the primary tumor or established metastases. In this study ErC was compared to TC, a standard regimen for (neo) adjuvant treatment. A companion exploratory analysis examined the EMT markers E-cadherin and vimentin, as well as the endothelial marker CD-31 assessing tumor vasculature. Final assessments of the primary endpoint of pathological complete response (pCR) and results of the correlative studies will be presented.

Methods: Women with histologically confirmed invasive HER2-negative (IHC 0-1+ or FISH/SISH negative), cT1-3, cN0-2, M0 (pN3a disease allowed) adenocarcinoma of the breast were eligible. Following a 10 pt lead-in to confirm the safety/feasibility of ErC, pts were randomized 2:1. Arm 1, Er 1.4 mg/m2 IV (Days 1 & 8) and C 600 mg/m2 IV (Day 1); Arm 2, T 75 mg/m2 IV and C 600 mg/m2 IV on Day 1, both regimens administered q 21 days x 6 cycles followed by surgery. Tumor samples were collected at baseline and from residual breast cancer at the time of surgery. Samples were assayed for E-cadherin, vimentin, and CD-31 expression by immunohistochemistry.

Results: Enrollment was completed 4/2014 (76 pts); 10 pts in lead-in phase, 66 pts were randomized (Arm 1, 44; Arm 2, 22). In the randomized population, 77% had invasive ductal adenocarcinoma; median tumor size 3.1 cm (range, 0.4-10cm; 29.5% were T3); axillary nodes clinically positive in 52%. 34% of pts were triple negative (TN). 59 pts (89%) underwent surgery after receiving neoadjuvant chemotherapy (NAC) on study. pCR rates were 9% and 18% on the TC and ErC arms respectively. 4/7 pts with pCR on the ErC arm were TN. tumor samples were analyzed from 69 pts (including lead-in pts) for expression of the EMT biomarkers. Of these, 40 pts had paired pre- and post-treatment samples, and 29 pts had either a pre- or post-treatment sample (including 8 pre-treatment samples from pts who achieved pCR). In pre-treatment tumor specimens (61 samples), E-cadherin levels were modest-high in 80%, vimentin expression was seen in 39%, and CD-31 expression observed in 21% of the samples. Analysis of pre- and post-treatment paired specimens and differential effects according to treatment regimen will be presented.

Conclusion: The observed pCR rate of 18% with ErC in this HER2- pt population was comparable with other NAC regimens. Correlative evaluation of EMT markers and tumor vascular density with response is ongoing and will be presented.

Citation Format: Yardley DA, Chandra P, Hart L, Wright GS, Ward P, Mani A, Shastry M, Finney L, Guo S, DeBusk LM, Hainsworth JD, Burris III HA. A phase II randomized study with eribulin/cyclophosphamide (ErC) and docetaxel/cyclophosphamide (TC) as neoadjuvant therapy in HER2-negative breast cancer- Final analysis of primary endpoint and correlative analysis results. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-06.

Abstract P1-12-04: A phase 2 study of eribulin in breast cancer not achieving a pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC)

Background: Residual breast cancer after NAC is associated with a high risk of recurrence. Little evidence supports the use of further chemotherapy in this setting. Eribulin, an inhibitor of microtubule dynamics, demonstrated a survival advantage in patients with metastatic breast cancer who had progressed after previous anthracycline and taxane therapy. This phase 2 trial assessed the efficacy of eribulin (2-yr disease-free survival) administered postoperatively to breast cancer pts not achieving a pCR following standard NAC.

Methods: Women with invasive breast cancer (stage T1-4b, N0-2, M0 at diagnosis) and evidence of residual cancer (>5 mm) in the breast or axillary lymph nodes (LN) following ≥4 cycles of standard anthracycline and/or taxane-containing NAC were eligible. Additional eligibility criteria: age ≥18 yrs, peripheral neuropathy < 1, adequate hematologic, hepatic, and renal function. 3 groups were studied: Cohort A-triple negative (TN), Cohort B-HR+/HER2-, Cohort C-HER2+. After recovery from definitive surgery, all pts received eribulin mesylate 1.4mg/m2 IV on days 1 and 8 every 21 days for 6 cycles. Cohort C pts also received trastuzumab 6mg/kg IV day 1 every 21 days for a total of 1 yr from start of NAC. Adjuvant hormonal therapy and loco-regional radiotherapy were administered per institutional guidelines. We hypothesized post-operative eribulin would result in a 40% increase over the reported 40% 2 yr DFS for TN, and a 15% increase over the reported 80% 2 yr DFS for HR+/HER2- pts who did not achieve pCR following standard NAC.

Results: 127 pts were enrolled (54, Cohort A; 42, Cohort B; 31, Cohort C). Pts on Cohort C continue with study treatment. Here, we present the results of 95 pts treated on Cohorts A and B. Median age-52 yrs (range, 27-74). 87 pts (92%) had invasive ductal adenocarcinoma, 6 (6%) invasive lobular, 1 (1%) mucinous, and 1 (1 %) unknown; 34 pts (36%) had T3 or T4 tumors and 65 (68%) had N1-2 disease at diagnosis. NAC with anthracyclines was administered to 74 pts (78%), taxanes to 88 (93%), and 72 (76%) received both. 71 pts (75%) had mastectomies, 24 (25%) had breast conserving surgery. Median residual tumor was 17.5 mm (range 0.1 to 80); 60 pts (63%) were LN+. 78 pts (81%) completed the planned 6 cycles of eribulin. Adjuvant radiation was administered in 28 pts (30%). 3 pts discontinued treatment due to toxicity (1 each with G3 neutropenia, G3 nausea, and unknown grade neuropathy). The most common treatment-related G3/4 adverse events were neutropenia [29 pts (31%)] and leukopenia [10 pts (11%)]. 3 pts (3%) had G3/4 febrile neutropenia and 2 pts (2%) had G3/4 neuropathy. Growth factors were administered to 22 pts (24%). There were no treatment-related deaths. With a median follow up of 19.2 and 14.9 months for Cohorts A and B respectively, the 2 yr DFS probabilities calculated from date of surgery were 61.1 % (95% CI-41.2-76.0) for Cohort A; 82.2% (95% CI-60.2-92.7) for Cohort B.

Conclusions: The addition of eribulin is safe and feasible in pts who do not achieve pCR following anthracycline and/or taxane based NAC. At a median follow up of 19.2 months, a statistically significant improvement in the estimated 2 yr DFS was evident in the TN (Cohort A) pts.

Citation Format: Yardley DA, Peacock N, Shroff S, Molthrop, Jr DC, Anz B, Daniel BR, Young RR, Weaver R, Harwin W, Webb CD, Ward P, Shastry M, DeBusk LM, Midha R, Hainsworth JD, Burris III HA. A phase 2 study of eribulin in breast cancer not achieving a pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-12-04.

Abstract P5-09-04: Consensus and disagreement between experts and community practitioners asked to make therapeutic recommendations for early breast cancer (EBC)

Intro. Most patients with stage II BC will receive surgery along with systemic therapy, but no consensus exists among experts on optimal use of neoadjuvant vs adjuvant therapy in many cases. Furthermore, treatment guidelines list multiple reasonable regimens for EBC, but lack patient-specific recommendations. We have shown previously that online decision support tools can affect treatment decisions of community practitioners. In this study, we sought to determine areas of consensus and disagreement among expert faculty providing treatment recommendations for a 2015 decision support tool on EBC as well as those using the online tool.

Methods. An online decision support tool was developed with input from 5 experts on systemic therapy recommendations for 235 patient scenarios in EBC. Tool users were asked to enter specific patient criteria and their intended management for each case before displaying the 5 expert recommendations for the user-entered case. Users were asked to indicate if the expert recommendations changed their intended approach.

Results. At interim analysis, 406 individuals used this tool, with 674 patient scenarios entered. Among users reporting on the tool's clinical impact, 88% indicated expert recommendations either confirmed or changed their intended therapy. Expert recommendations in the tool showed areas of consensus and disagreement in treating patients with EBC. For example, expert recommendations varied in the choice of systemic therapy prior to surgery and when to continue directly to surgery before systemic treatment.

Expert recommendations for initiating systemic neoadjuvant therapy in HER2-, HR+ EBCcNcTExpert 1Expert 2Expert 3Expert 4Expert 5NCCN GuidelinesNegativecT1a       cT1b       cT1c    Recommend  cT2 RecommendConsider cT3ConsiderRecommendConsiderPositivecT1a   RecommendConsider cT1b   RecommendConsider cT1c   RecommendConsider cT2ConsiderRecommendConsider cT3ConsiderRecommendConsider

Experts did agree on starting with surgery in patients with node-negative, T1a disease; however, only 30% of tool users agreed. Both experts and users agreed in recommending systemic neoadjuvant therapy for patients with HER2+, node-positive T2 disease. In patients with HER2+ EBC, experts always chose to include dual HER2-targeted therapy in neoadjuvant systemic therapy but only included trastuzumab in adjuvant regimens. However, only 51% of tool users selected dual HER2-targeted therapy as part of neoadjuvant therapy and 13% use dual HER2-targeted therapy in the adjuvant setting. Expert opinion varied on when to use adjuvant chemotherapy in patients with HR+, HER2- EBC, particularly for those with intermediate or unknown recurrence scores and no lymph node involvement. Detailed comparison of expert consensus and disagreement, analysis of practice pattern information from user responses, and perceived impact of the expert recommendations will be presented.

Conclusions. This EBC tool highlights specific clinical scenarios having either consensus or disagreement among experts and community practitioners. Education that includes online decision support tools may increase the number of clinicians making optimal treatment decisions for patients with EBC.

Citation Format: Obholz KL, Rosenthal KM, O'Regan RM, Swain SM, Yardley DA, Brady ED. Consensus and disagreement between experts and community practitioners asked to make therapeutic recommendations for early breast cancer (EBC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-09-04.

Abstract OT3-01-01: HERMIONE: A phase 2, randomized, open label trial comparing MM-302 plus trastuzumab with chemotherapy of physician's choice plus trastuzumab, in anthracycline naive HER2-positive, locally advanced/metastatic breast cancer patients previously treated with pertuzumab and ado-trastuzumab emtansine (T-DM1)

Background: Although HER2-targeted therapies such as pertuzumab and T-DM1 have improved patient outcomes, treatment resistance typically occurs. MM-302 is a HER2-targeted liposomal doxorubicin in development by Merrimack Pharmaceuticals. In a Phase 1 study, patients with HER2-positive metastatic breast cancer (MBC) were treated with MM-302 alone and in combination with trastuzumab with or without cyclophosphamide. MM-302 had an acceptable safety profile and promising efficacy was observed in patients not previously exposed to an anthracycline.

Trial design: HERMIONE (NCT02213744) is a randomized Phase 2, two-arm, open-label trial designed to evaluate if MM-302 can address an unmet medical need in patients with anthracycline naïve, trastuzumab-, pertuzumab- and T-DM1-pretreated HER2-positive locally advanced breast cancer (LABC)/MBC. Patients are randomized 1:1 to receive MM-302 (30mg/m2, Q3W) plus trastuzumab (6mg/kg, Q3W) or chemotherapy of physician's choice (vinorelbine, capecitabine, or gemcitabine) plus trastuzumab (6mg/kg, Q3W).

Eligibility criteria: Centrally confirmed HER2-positive LABC/MBC, no prior anthracycline exposure, prior trastuzumab in any setting, prior pertuzumab and T-DM1 in the LABC/MBC setting, unlimited prior lines of therapy, ECOG 0-1 and LVEF ≥50%. CNS metastases are permitted if stable and without symptoms or steroids for 4 weeks.

Specific aims: The primary endpoint is independently assessed progression free survival (PFS). Secondary endpoints include investigator assessed PFS, overall survival, response rate, safety and patient related outcomes.

Statistics: 250 patients will be enrolled to observe 191 PFS events for 90% power to detect a Hazard Ratio of 0.625. The MM-302 arm will be compared to the control arm on the primary endpoint of PFS using a stratified log-rank test at one-sided 0.025 level.

Accrual status: First patient in was December 2014 and enrollment is expected to be complete in late 2016. Sites are open in the US, Canada and Western Europe and are currently enrolling patients.

Citation Format: Miller K, Cortes J, Hurvitz SA, Krop IE, Tripathy D, Verma S, Riahi K, Reynolds JG, Wickham T, Molnar I, Yardley DA. HERMIONE: A phase 2, randomized, open label trial comparing MM-302 plus trastuzumab with chemotherapy of physician's choice plus trastuzumab, in anthracycline naive HER2-positive, locally advanced/metastatic breast cancer patients previously treated with pertuzumab and ado-trastuzumab emtansine (T-DM1). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT3-01-01.

Abstract P5-14-04: A phase 2 study evaluating orteronel, an inhibitor of androgen biosynthesis, in patients with androgen receptor (AR)-expressing metastatic breast cancer: Interim analysis

Background: The frequency of AR expression varies in the different breast cancer subtypes with 88%, 59%, and 32% expression reported in ER+, HER2+, and triple negative tumors, respectively. AR expression is associated with resistance to endocrine therapy in ER+ breast cancer. Androgen levels frequently increase following treatment with aromatase inhibitors suggesting a role for androgen synthesis inhibitors in ER+ breast cancer. AR signaling and expression are seen in triple negative breast cancer (TNBC), and a distinct AR TNBC subtype can be identified by gene expression profiling. AR expression in TNBC offers a potential therapeutic target. Preclinical and clinical studies demonstrated anti-androgen agent activity in breast cancer cell lines; preliminary clinical data suggests activity in TNBC. Orteronel is a novel, oral, selective, nonsteroidal inhibitor of 17, 20-lyase, a key enzyme in androgen biosynthesis that is being evaluated as endocrine therapy in various hormone-sensitive cancers. In this phase 2 study we are evaluating single agent orteronel in AR+ MBC.

Methods: Pts with AR expressing MBC (≥10% staining by central immunohistochemistry) were eligible. Pts were grouped into 2 cohorts for analysis: Cohort 1-TNBC and Cohort 2-ER+ (HER2 could be +/- in this cohort). Pts must have been previously treated with standard therapy for MBC (1-3 chemotherapy regimens for TNBC, 1-3 hormonal therapies + 1 chemotherapy for ER+ patients, ≥2 HER2-targeted regimens for HER2+ patients). A 6 pt lead-in for safety and tolerability of orteronel in AR+ female MBC pts was followed by open enrollment to either cohort. All pts received 300 mg orteronel PO BID over a 4 week cycle and underwent response assessment every 2 cycles. Treatment was continued until disease progression or unacceptable toxicity. The hypothesized response rate for Cohort 1 was 10% and 13% for Cohort 2. We present the results of a protocol-specified interim analysis of the ER+ MBC pts (Cohort 2).

Results: From 3/2014 to 4/2015, a total of 29 pts were enrolled on cohort 2. Median age was 65 years (range, 39-79); 90% ECOG ≤1; 90% HER2-/10% HER2+; median of 7 prior therapies (range 3-11). 93% had prior chemotherapy. Pts received a median of 2 cycles of orteronel treatment (range 1-4) and 3 pts (10%) are still on treatment. Of the 26 pts (90%) pts that have discontinued, 19 (66%) discontinued due to disease progression, 4 (14%) due to pt decision, 2 (7%) due to adverse event (AE), and 1 (3%) due to non-compliance. The most common treatment-related G 3/4 AEs were increased lipase [3 pts (10%)] and hypertension [2 pts (7%)]. There were no treatment-related SAEs or deaths on study. Three pts (10%) had stable disease as their best response. Further response evaluation is underway.

Conclusions: Orteronel monotherapy was well tolerated but appears to have limited single-agent activity in this heavily pre-treated ER+ MBC pt population. The full results from this interim analysis will be presented.

Citation Format: Yardley DA, Peacock N, Young RR, Silber A, Chung G, Webb CD, Jones SF, Shastry M, Midha R, DeBusk LM, Hainsworth JD, Burris HA. A phase 2 study evaluating orteronel, an inhibitor of androgen biosynthesis, in patients with androgen receptor (AR)-expressing metastatic breast cancer: Interim analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-14-04.

Abstract OT1-03-15: The METRIC trial: A randomized international study of the antibody-drug conjugate glembatumumab vedotin (GV or CDX-011) in patients with metastatic gpNMB-overexpressing triple-negative breast cancer (TNBC)

Background

Glycoprotein NMB (gpNMB) is an internalizable transmembrane protein overexpressed in approximately 20% of breast cancer (BC), including approximately 40% of TNBC. gpNMB is a poor prognostic marker in BC (Rose CCR 2010) and preclinically has been implicated in tumor invasion, metastasis, and angiogenesis. GV is a novel antibody-drug conjugate targeting the potent cytotoxin monomethylauristatin E (MMAE) to gpNMB overexpressing cancer cells.

In a Phase I/II study and the Phase II "EMERGE" study, GV demonstrated promising activity with TNBC patients (pts) deriving the greatest benefit and exhibiting the highest degree of gpNMB overexpression. GV was well-tolerated with the most frequent treatment-related toxicities consisting of rash, neutropenia, and neuropathy. In subset analyses of the EMERGE trial, objective response rate (ORR) was 30% (7/23) for GV vs. 9% (1/11) for investigator's choice in tumors with gpNMB overexpression (>25% of tumor epithelium); 18% (5/28) vs. 0% (0/11) in TNBC; and 40% (4/10) vs. 0% (0/6) in gpNMB-overexpressing TNBC for GV and IC respectively, with apparent improvements in progression-free survival (PFS; hazard ratio (HR) = 0.11) and overall survival (OS; HR = 0.14).

Trial design

The METRIC Trial (NCT#01997333) is an international (USA, CA, Aus), two-arm phase II study. Pts are randomized 2:1 to GV (1.88 mg/kg IV q 21 days) or capecitabine, a current standard of care for this population (2,500 mg/m2 daily for d1-14, q21 days) until progression or intolerance. Crossover is not permitted.

Eligibility criteria

Key eligibility criteria include: >25% of tumor epithelium gpNMB+ by central immunohistochemistry (IHC) screening of archival tissue; estrogen receptor and progesterone receptor <10% and HER2 negative [0-1+ IHC, or ISH copy number <4.0/ratio <2.0] by local assessment; ECOG 0-1; taxane resistance; anthracycline exposure (if indicated); <2 chemotherapy regimens for advanced BC; measurable disease; no persistent Grade >2 toxicity.

Specific aims

The primary endpoint is PFS per independent, blinded central review committee according to RECIST 1.1. Secondary endpoints are ORR, duration of response, OS, safety, pharmacokinetics and pharmacodynamics. Exploratory endpoints are quality of life and/or cancer-related pain.

Statistical methods and target accrual

The trial has 85% power to detect a PFS HR of 0.64 with two sided α = 0.05. The hypothesized median PFS is 4.0 months for capecitabine and 6.25 months for GV. Target accrual is open for 300 pts.

Citation Format: Melisko M, Yardley DA, Blackwell K, Forero A, Ma C, Montero A, Daniel BR, Wright G, Fehrenbacher L, Chew H, Ferrario C, Nanda R, Seiler Jr M, Guthrie T, Vance K, Ouellette G, He Y, Bagley RG, Zhang J, Vahdat LT. The METRIC trial: A randomized international study of the antibody-drug conjugate glembatumumab vedotin (GV or CDX-011) in patients with metastatic gpNMB-overexpressing triple-negative breast cancer (TNBC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-03-15.

Randomized, phase II, placebo-controlled trial of onartuzumab and/or bevacizumab in combination with weekly paclitaxel in patients with metastatic triple-negative breast cancer

BACKGROUND

Increased hepatocyte growth factor/MET signaling is associated with an aggressive phenotype and poor prognosis in triple-negative breast cancer (TNBC). We evaluated the benefit of adding onartuzumab, a monoclonal anti-MET antibody, to paclitaxel with/without bevacizumab in patients with TNBC.

PATIENTS AND METHODS

Women with metastatic TNBC were randomized to receive onartuzumab plus placebo plus weekly paclitaxel (OP; n = 60) or onartuzumab plus bevacizumab plus paclitaxel (OBP; n = 63) or placebo plus bevacizumab plus paclitaxel (BP; n = 62). The primary end point was progression-free survival (PFS); additional end points included overall survival (OS), objective response rate (ORR), and safety. This trial was hypothesis generating and did not have power to detect minimum clinically meaningful differences between treatment arms.

RESULTS

There was no improvement in PFS with the addition of onartuzumab to BP [hazard ratio (HR), 1.08; 95% confidence interval (CI) 0.69-1.70]; the risk of a PFS event was higher with OP than with BP (HR, 1.74; 95% CI 1.13-2.68). Most patients had MET-negative tumors (88%); PAM50 subtype analysis showed basal-like tumors in 68% of samples. ORR was higher in the bevacizumab arms (OBP: 42.2%; 95% CI 28.6-57.1; BP: 54.7%; 95% CI 41.0-68.4) compared with OP (27.5%; 95% CI 15.9-40.6). Median OS was shorter with OBP (HR, 1.36; 95% CI 0.75-2.46) and OP (HR, 1.92; 95% CI 1.03-3.59), than with BP. Peripheral edema was more frequent in the onartuzumab arms (OBP, 51.8%; OP, 58.6%) versus BP (17.7%).

CONCLUSION

This study did not show a clinical benefit of the addition of onartuzumab to paclitaxel with/without bevacizumab in patients with predominantly MET-negative TNBC.

CLINICALTRIALSGOV

NCT01186991.

Abstract OT2-6-16: A pivotal multicenter, randomized, study evaluating the novel antibody-drug conjugate CDX-011 in patients with metastatic, triple-negative, high GPNMB over-expressing breast cancer

Background: GPNMB is an internalizable transmembrane glycoprotein overexpressed in multiple tumor types where it is a poor prognostic factor. Its functions appear to include mediating intercellular adhesion, promoting tissue repair, and regulating cell growth and differentiation. In tumor cell lines including breast cancer (BC), GPNMB enhances tumor growth and bone metastases. Relative to other BC subtypes, triple-negative BC (TNBC) highly over-expresses GPNMB in tumor epithelium where it correlates with a higher risk of recurrence. CDX-011 (glembatumumab vedotin) is a fully human GPNMB-specific monoclonal antibody drug conjugate combining the tumor-targeting GPNMB antibody with the potent cytotoxic microtubule inhibitor, monomethylauristatin E (MMAE). In the Phase II EMERGE study, 122 patients (pts) with heavily pre-treated BC (2-7 priors) and GPNMB-expression by IHC in ≥ 5% of either the tumor epithelial or stromal cells in archival tissue were randomized 2:1 to receive CDX-011 or “investigator's choice” (IC) single-agent chemotherapy, with crossover to CDX-011 permitted. CDX-011 as compared to IC, demonstrated higher objective response rates, with ORR of 8/25 (32%) vs 1/8 (13%) for high GPNMB expression (defined as expression in ≥25% of epithelial tumor cells) and 5/27 (19%) vs. 0/9 (0%) for TNBC. In the presence of both TNBC and high GPNMB, ORR was 4/12 (33%) vs 0/4 (0%) which corresponded to a doubling of median progression-free survival (PFS, p = 0.008) and median overall survival (OS, p = 0.003). CDX-011 was well tolerated with less hematologic toxicity (neutropenia: 29% vs 44%; leukopenia: 10% vs 27%; thrombocytopenia: 4% vs. 15%) but more rash (47% vs. 2%) and neuropathy (23% vs 12%) than IC. Methods: The current pivotal study aims to evaluate CDX-011 in metastatic GPNMB-over-expressing TNBC defined as ER and PR < 1%, HER2 negative (0-1+ IHC, or FISH ratio < 1.8). Eligibility criteria include >25% tumor epithelium GPNMB expression by central IHC; taxane and anthracyline resistance; ≤1 prior chemotherapy regimen for advanced BC; measurable disease by RECIST 1:1 and no persistent treatment-related toxicity of ≥ Grade 2 severity. 300 pts will be randomized (2:1) to receive CDX-011 (1.88 mg/kg IV q 21 days) or capecitabine (2500 mg/m2 daily for d1-14, q21 days) until progression or toxicity. Disease assessments are performed every six weeks for 6 months, and every 12 weeks thereafter. All pts are subsequently followed for survival. Endpoints are ORR and PFS (co-primary), duration of response, OS, safety, pharmacokinetics, and quality of life; tumor response assessments will be assessed by central review per RECIST 1.1. The trial has 80% power to detect a hazard ratio of 0.64 for PFS with α = 0.01 and/or a 30% increase in ORR (from 15% to 30%) with α = 0.04. For further information, contact info@celldextherapeutics.com.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT2-6-16.

Abstract OT1-1-13: A phase II study with lead-in safety cohort of cabazitaxel plus lapatinib as therapy for patients with HER2-positive metastatic breast cancer (MBC) and intracranial metastases

Background: HER2-targeted therapy has improved the progress of patients (pts) with HER2-positive breast cancer; however, CNS metastases remain a significant source of morbidity and mortality. It is hypothesized that the inability of drugs like trastuzumab to cross the intact blood-brain barrier (BBB) may render the CNS as a sanctuary site for metastases. Lapatinib is an oral small molecule tyrosine kinase EGFR1/HER2 inhibitor that crosses the BBB and has activity against CNS metastases. Cabazitaxel is a new taxoid that is active in docetaxel- or paclitaxel-resistant breast cancer, and differs from other taxanes in its ability to cross the BBB. The promising systemic activity shown by cabazitaxel in taxane-resistant MBC coupled with the CNS penetrance of both cabazitaxel and lapatinib make this an attractive combination to evaluate in HER2-positive MBC pts with CNS metastases.

Study Objectives: The primary objectives of the study are to determine the safety and CNS objective response rate (ORR = CR+PR) in HER2-positive MBC pts with CNS metastases when treated with cabazitaxel and lapatinib. The secondary objectives include evaluation of the clinical benefit rate (CBR), 3- and 6-month PFS rate for CNS metastases, and response rate and CBR for extra-cranial metastases.

Key eligibility: Pts >18 yrs with HER2-positive (IHC 3+ or FISH/SISH-positive) MBC and unequivocal evidence of brain metastases are eligible. Additional eligibility criteria include: at least one measurable brain lesion >1.0cm in longest dimension on MRI; pts with brain lesions previously treated with WBRT and/or SRS must have at least one intra-cranial lesion >1.0cm not treated with SRS and must have evidence of intra-cranial progressive disease. Pts must have received at least 1 prior HER2-directed therapy in the adjuvant or metastatic setting; pts without prior chemotherapy for MBC are eligible if they progressed during or within 6 months of adjuvant therapy. Otherwise, there is no specific minimum or maximum number of previous chemotherapy regimens for MBC. ECOG performance status 0-2, adequate renal, bone marrow, and hepatic function are required; prior treatment with cabazitaxel or lapatinib (for MBC) not permitted.

Trial design: This is an open-label, non-randomized, phase II study with a lead-in safety cohort. During the lead-in phase, 6-15 pts will be treated in cohorts of 3 with increasing doses of cabazitaxel and lapatinib to determine the tolerability and optimal dose. Once the safety and dose is confirmed, subsequent pts will be treated at the optimal dose of the 2 agents. Each treatment cycle is 3 weeks and restaging will occur systemically and intra-cranially every 2 cycles for the first 8 cycles and every 3 cycles thereafter until progressive disease or unacceptable toxicity.

Statistical methods: We hypothesize that the addition of cabazitaxel will increase the CNS ORR from 6% (expected with single agent lapatinib) to ≥20% in this pt population. Treatment of 27 evaluable pts with the identified phase II doses will detect this difference with a power of 80% and alpha = 10% (one-sided test). Accounting for a 10% inevaluable rate and lead-in pts, a total of 45 pts will be enrolled on the study.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT1-1-13.

Abstract PD4-3: Use of community-based next-generation sequencing (NGS) in advanced breast cancer: Identification of actionable targets to guide clinical trial selection

Background: Molecularly targeted drugs specific for mutated genes are increasingly the focus of novel clinical trials. However, molecular profiling of tumors is largely unavailable in community cancer centers, where nearly 80% of cancer patients (pts) are treated. In October 2012, Sarah Cannon Research Institute (SCRI) launched a community-based molecular profiling initiative to characterize the spectrum of molecular alterations in tumors. The profiling panel focused on potentially actionable mutations for the purpose of identifying candidates for treatment with specific targeted agents (FDA approved or investigational). Herein, we report the initial data from breast cancers (BC) profiled between October 2012 and May 2013.

Methods: Metastatic breast cancer (MBC) pts > 18 years of age with ECOG PS ≤ 2 who were candidates for treatment provided consent for tumor molecular profiling. Archival tumor specimens (tissue block or 10 unstained slides) obtained from either the primary or metastatic disease were collected and interrogated by NGS (1000X average coverage) in a CLIA/CAP laboratory to detect oncogenic hotspot mutations in 35 cancer-related genes. Results were reported to the treating physician within 12 calendar days of receipt of suitable tissue and were stored in a database to enable correlation with clinical outcomes. Detection of relevant molecular abnormalities was used to identify pts appropriate for clinical trials of targeted agents.

Results: As of May 31 2013, a total of 594 tumor samples were profiled, 101 (17%) of which were BC samples. 8% (8/101) of the BC samples were inadequate for assay. Of the remaining 93 samples, 60 (65%) had no mutations detected. 28% of BC had single mutations and 7% had multiple mutations. PIK3CA mutations (24%) were the most frequently identified alteration. Other genetic alterations identified included RUNX1 (4%) and FGFR3 (2%) while mutations in PIK3R1, MET, KRAS, KIT, FGFR2, HER2, BRAF, SMO, MYC, DDR2 and AKT1 were infrequent, each identified in 1 pt. Patterns and frequency of mutations in the 35 genes assayed differed in the various subtypes of BC. 6% (6/93) of BC pts with appropriate tumor mutations identified by molecular profiling have been enrolled into phase I clinical trials with PI3K or mTORC1/2 inhibitors; updated treatment results will be presented. An additional 27 patients are potentially eligible for ongoing trials at SCRI.

Conclusions: This community-based molecular profiling initiative has been well accepted by patients and physicians, and provides timely results. Potentially actionable mutations were identified in 35% of BCs tested; PIK3CA mutations accounted for 70% of all actionable mutations detected. Identification of BC patients with actionable mutations may add to treatment options and improve results, and will also accelerate development of new targeted agents.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD4-3.

Abstract P2-16-17: Characterization of response to everolimus (EVE) in BOLERO-2: A phase 3 trial of EVE plus exemestane (EXE) in postmenopausal women with HR+, HER2- advanced breast cancer

Introduction: The BOLERO-2 trial demonstrated that combining the oral mammalian target of rapamycin (mTOR) inhibitor, EVE, with the steroidal aromatase inhibitor, EXE, more than doubled median progression-free survival (PFS) compared with placebo (PBO) plus EXE in postmenopausal women with hormone-receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2−) breast cancer (BC) who relapsed or progressed following a nonsteroidal aromatase inhibitor (NSAI). Patients also achieved responses per Response Evaluation Criteria in Solid Tumors (RECIST) during treatment with EVE+EXE.

Methods: The phase 3, double-blind, BOLERO-2 trial randomized postmenopausal women with HR+ BC progressing or recurring after NSAIs in a 2:1 manner to EVE 10 mg once daily plus EXE 25 mg once daily (EVE+EXE; n = 485) or placebo (PBO) plus EXE (PBO+EXE; n = 239). The primary endpoint was PFS by local assessment. Overall response rate (ORR; complete + partial response per investigator assessment based on RECIST 1.0) and duration of overall response were secondary endpoints. In addition, best percentage change from baseline in sum of longest diameters of target lesions was assessed.

Results: At the time of final PFS analyses at 18 months’ median follow-up, ORR was significantly higher in the EVE+EXE arm compared with the PBO+EXE arm (12.6% vs 1.7%, respectively, by local assessment; P<.0001). Among patients with measurable disease at baseline, 71% in the EVE+EXE arm had a decrease in the sum of longest diameters of target lesions compared with baseline vs 30% in the PBO+EXE arm. Median duration of overall response was 10.5 months (95% confidence interval [CI]: 8.2, 21.9 months) for EVE+EXE and 6.9 months (95% CI: 4.2, 6.9 months) for PBO+EXE. Of note, only 4 patients in the PBO+EXE arm had an objective response to treatment.

Conclusions: In addition to PFS, the combination of EVE plus EXE significantly improved ORR vs PBO+EXE in patients with HR+, HER2− advanced BC progressing during or after NSAI therapy. Furthermore, greater than two-thirds of patients treated with EVE+EXE experienced tumor shrinkage during treatment. These results further support the rationale for combining EVE with EXE to improve clinical outcomes in HR+, HER2− advanced BC progressing after NSAI therapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-17.

Abstract P4-16-04: Amrubicin as second- or third-line treatment for patients with HER2-negative metastatic breast cancer (MBC): Final results from a phase II trial of the Sarah Cannon Research Institute (SCRI)

Background: Anthracyclines are among the most effective agents in the treatment of breast cancer; however, dose-dependent cumulative cardiotoxicity limits their use. Amrubicin is a synthetic anthracycline topoisomerase II inhibitor demonstrating potent antitumor effects coupled with little potential for cardiotoxicity. We report the final results from a phase I/II trial of amrubicin as second- or third-line therapy for HER2-negative MBC.

Methods: Eligible patients (pts) included women with measurable HER2-negative MBC who had received 1 or 2 prior chemotherapy regimens for MBC. Previous anthracyclines were permitted if ≥ 6 months prior to study entry. Normal LVEF was required. Amrubicin 110 mg/m2 IV (dose established from phase I portion) was administered every 3 weeks until disease progression or intolerable toxicity; growth factor use was permitted. Disease evaluations were performed every 6 weeks and LVEF assessments every 12 weeks. Progression-free survival (PFS) was the primary endpoint; a median PFS ≥ 4.5 months would merit further evaluation of amrubicin in MBC. Toxicity, overall survival, and overall response rate (ORR) were secondary endpoints.

Results: Between 1/2010 and 3/2012, 78 pts were enrolled, and 66 pts are included in this analysis (ph I: 3 pts; ph II 63 pts). Baseline characteristics included: median age 59 years; hepatic metastases in 50%; ≥ 3 sites of metastatic disease in 32%. Triple-negative histology was noted in 27%; prior adjuvant chemotherapy in 50%; prior anthracyclines in 32%; and 2 prior cytotoxic regimens for MBC in 35%. Median treatment duration was 18 weeks (6 cycles), range 1- 24 cycles. The ORR was 21% in evaluable pts (2 CR, 10 PR); 5 of these 12 pts had prior anthracyclines. 14% were not evaluable. The clinical benefit rate (CBR) was 42% (CBR = CR+PR+SD≥ 4 months); 35% of these responders received ≥12 cycles of amrubicin. Median PFS for all pts was 4.0 months (95% CI 2.5- 5.8 months) and did not significantly differ by line of therapy administered (4.0 months as 2nd line vs 4.7 as 3rd line therapy). 36% of pts were free of progression at 6 months. Neutropenia was the most common grade 3/4 toxicity present in 42% and accompanied by fever in 7%. No grade 3/4 non-hematologic toxicity occurred in > 5% pts. One pt previously treated with anthracyclines experienced a transient 20% LVEF decline to 44% at cycle 4. This recovered to baseline within 2 weeks and pt continued to receive 2 additional cycles of amrubicin before experiencing PD. No other grade 3/4 cardiac events were noted. In 3 pts, amrubicin was discontinued due to toxicity (G4 neutropenia, G2 thrombocytopenia, G2 nausea/vomiting/vertigo).

Conclusions: Amrubicin was active and well tolerated in the second- or third-line MBC setting with manageable toxicity. The ORR of 21% and median PFS of 4 months are comparable to other single agents in this setting. The observed CBR of 42%, and the fact that nearly 1/3 of these responders received ≥12 cycles of amrubicin with no cardiotoxicity, suggests that future evaluations of amrubicin in breast cancer are warranted.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-16-04.

Abstract P5-20-10: Panitumumab, Gemcitabine and Carboplatin in Triple-Negative Metastatic Breast Cancer: Preliminary Results of a Phase II Trial of the Sarah Cannon Research Institute

Background: Triple-negative breast cancer (TNBC) is a poor prognosis subtype with treatment limited to chemotherapy. Over expression of epidermal growth factor receptor (EGFR) occurs in up to 70% of TNBC providing a potential targetable receptor for treatment. Panitumumab is an approved fully human, IgG2 monoclonal anti-EGFR antibody that inhibits intracellular growth signals dependent on receptor activation. The gemcitabine/platinum combination has demonstrated activity in metastatic as well as TNBC at various schedules and doses. We therefore investigated the efficacy and safety of panitumumab in combination with gemcitabine and carboplatin in patients (pts) with TNBC.

Methods: Eligibility criteria included: females with metastatic TNBC, 0–1 prior chemotherapy regimen for metastatic disease, ECOG PS 0–1, no brain metastases, no previous EGFR inhibitors and adequate organ function. All pts received gemcitabine 1500 mg/m2 IV, carboplatin AUC = 2.5 IV, and panitumumab 6 mg/kg IV every 2 weeks. A prophylactic skin regimen consisting of moisturizer, sunscreen and topical steroid was to be used 24 hours prior to study treatment and continued until panitumumab was discontinued. Pts were restaged after 3 treatment cycles and continued treatment until unacceptable toxicity or disease progression. If treatment benefit was demonstrated, and pts were experiencing toxicity or intolerance to gemcitabine, carboplatin or both, pts were allowed to discontinue either one or both agents and continue study treatment with panitumumab as a single agent or in combination. The primary endpoint of this study is progression free survival (PFS) with accrual of 70 pts necessary to detect an improvement in median PFS from 3.6 to 5.4 months (80% power, 10% level of significance).

Results: Between May 2010 and May 2012, 61 patients were enrolled with an accrual goal of 70 pts. This analysis is based on 47 pts. Pt characteristics include: median age 56, prior hormonal therapy 4%, no prior chemotherapy for metastatic disease in 87% (28% de novo stage IV), 1 prior chemotherapy for metastatic disease in 13%. Sites of metastatic disease included local regional/lymph nodes 70%, lung 57%, liver 32%, bone 26%, and others 23%. Best response to treatment was as follows: CR − 1 (2%), PR − 14 (30%), SD − 20 (43%), PD − 11 (23%), UE − 1 (2%). As 1st line TNBC therapy, the ORR was 34%. The most common grade 3/4 heme toxicities were neutropenia − 12 (25%), leucopenia − 7 (15%), anemia − 3 (6%) and thrombocytopenia − 2 (4%). Grade 3/4 non-hematologic toxicities were rash − 4 (9% with 1 grade 4), fatigue − 3 (6%) and DVT − 3 (6%). Grade 1 and 2 rash was present in 19 and 9 pts respectively. Archival tumor tissue was collected for correlative biomarker analysis to include PI3KCA, p53, PTEN, EGFR, and K-ras status.

Conclusions: The addition of panitumumab to gemcitabine and carboplatin in metastatic TNBC was active with an ORR of 32%. No new safety signals were identified and treatment was generally well tolerated with easily manageable toxicity. Full study results and correlative biomarker assessments will be reported.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-20-10.

Abstract P5-17-05: Sorafenib plus Ixabepilone as First-Line Treatment for Patients with HER2-Negative Metastatic Breast Cancer: Preliminary Results of the Phase II Trial of the Sarah Cannon Research Institute

Background: Sorafenib (S) is an oral multi-kinase inhibitor with effects on tumor proliferation and angiogenesis, targeting VEGFR1 and VEGFR2. It has modest activity as a single agent in breast cancer. In combination with capecitabine, S demonstrated a significant improvement of 2.3 months in progression free survival (PFS) in patients (pts) with metastatic breast cancer (MBC) and added benefit when combined with paclitaxel. Ixabepilone (Ixa) is a semi-synthetic analog of epothilone B with excellent single agent activity in MBC. The phase I portion of this trial identified the MTD of the Ixa and S combination. We now report the initial results of the phase II trial with this novel combination.

Methods: Eligibility criteria included: HER2-negative MBC previously untreated with chemotherapy; measurable disease; ECOG PS 0–2; normal LVEF; and adequate bone marrow and organ function. Prior hormonal therapy for MBC was permitted. Pts received Ixa 32mg/m2 IV on day 1 of each 21-day cycle and S 400mg PO BID. Following a minimum of 4 cycles of the combination, responding pts could discontinue Ixa and remain on study treatment with S monotherapy. Granulocyte-stimulating growth factors were permitted after cycle one. Tumor assessments were performed every 9 weeks. Pts continued study treatment until disease progression or unacceptable toxicity. The primary endpoint of this trial was PFS; the addition of S to Ixa was hypothesized to improve PFS from 4.2 month to 6.2 months in this patient population. The total enrollment goal is 85 pts, and the trial is currently open to accrual.

Results: Between 5/2010 and 4/2012, 76 pts have been enrolled, and 57 pts (56 females, 1 male) are included in this analysis. Baseline characteristics included: median age 58; 61% were ER and/or PR positive; 39% were triple-negative; 39% received neoadjuvant therapy. Anthracycline exposure was noted in 34 pts and prior taxane exposure in 39 pts. 29 pts received prior hormonal therapy, 7 of these for MBC. Sites of metastatic disease included lymph nodes 42%, lung 35%, liver 30%, bone 30%, and 23% other. 19 pts (33%) had 3 or more sites of metastatic disease. Median treatment duration was 3 cycles (9 weeks), range 1–11+ cycles with 9 pts discontinuing Ixa after a median of 6 cycles and continuing on S monotherapy. 12 pts (21%) had objective responses (1 CR, 11 PR); 3 of the 22 (14%) triple-negative patients had responses (1 CR, 2 PR). An additional 24 patients (42%) had stable disease at first reevaluation. Neutropenia was the most common grade 3/4 toxicity (26%) with growth factor use reported in 35%. Grade 3/4 non-hematologic toxicity occurring in > 5% of patients consisted of: rash (12%), fatigue (11%), hypersensitivity reaction (7%, Ixa= 3 pts and S= 1 pt), and neuropathy (7%). Discontinuation due to adverse events occurred in 11%.

Conclusion: The combination of Ixa and full dose S was well tolerated with no new observed toxicities. Adverse events were manageable and consisted primarily of G3/4 neutropenia and rash. Study is ongoing and updated results will be presented.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-17-05.

Abstract P2-05-06: Quantitative measurement of HER2 expression in breast cancers: comparison with “real world” HER2 testing in a multi-center Collaborative Biomarker Study (CBS) and correlation with clinicopathological features

Background: Accurate determination of HER2 status is critical in determining appropriate therapy for breast cancer patients. The HERmark® assay is a novel method to quantitatively measure HER2 total protein expression (H2T) in breast cancer. In this study, we compared HERmark H2T with central laboratory HER2 retesting and local (site reported) HER2 testing of formalin-fixed, paraffin-embedded (FFPE) breast cancer tissues. The quantitative total HER2 measurements (H2T) by HERmark and results of local HER2 tests were correlated with tumor pathohistological characteristics and overall survival of breast cancer patients.

Methods: 232 FFPE breast cancer tissues were provided by 11 CBS study sites for HER2 testing by the HERmark assay and central laboratory IHC re-testing performed in blinded fashion. Local HER2 immunohistochemistry and/or fluorescence in situ hybridization (FISH) results and valid HERmark H2T and central HER2 IHC results were obtained in 192 cases for analysis.

Results: H2T showed a significant correlation with central HER2 IHC staining intensity (P < 0.0001). The concordance rates of positive and negative HERmark status (excluding equivocal) with those of local HER2 status determined by the CBS sites, and with those of central HER2 IHC status were 84% (Kappa = 0.68) and 96% (Kappa = 0.91), respectively. Higher H2T levels significantly correlated with higher tumor grade (p = 0.007) and negative ER/PR status (p = 0.002). Twenty-six (14%) cases showed discordant (conversion of negative and positive) results between local HER2 status and HERmark status. Of the discordant cases, HERmark significantly agreed with H-score of central HER2 IHC retesting (p = 0.014), as compared with local HER2 status. The concordant negative group (local HER2 negative/H2T low) demonstrated better overall survival (OS) (HR = 0.198, p = 0.0001), compared to that of concordant positive group (local HER2 positive/H2T high). The concordant negative group also showed better OS than that of discordant local HER2 negative/H2T high group (HR = 0.065, p = 0.0003), but showed no significant difference in OS as compared to that of discordant local HER2 positive/H2T low group (HR = 1.774, p = 0.499).). In 24 cases (13%) considered to be “triple negative” by local HER2, ER and PR testing, HERmark re-classified 4 cases (17%) as HER2 positive.

Conclusions: H2T by HERmark yields a continuum of quantitative HER2 protein measurements that shows an excellent correlation with central HER2 IHC retesting and confirms the known correlations between HER2 expression with tumor grade and ER/PR status. OS results of concordant HER2 positive or negative groups (between local HER2 testing and HERmark H2T) confirmed that HER2 positive patients (excluding adjuvant trastuzumab therapy) have worse OS than patients with HER2 negative disease. However, in the HERmark and local HER2 discordant groups, OS appeared to track better with H2T by HERmark and not with the local HER2 status. Novel quantitative HER2 measurements may identify patients with false (+) and (−) HER2 status by local HER2 testing and may provide added clinical value to routine “real world” HER2 testing.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-05-06.

Abstract OT3-3-08: Eribulin/Cyclophosphamide versus Docetaxel/Cyclophosphamide as Neoadjuvant Therapy in Locally Advanced HER2-Negative Breast Cancer: A Randomized Phase II Trial of the Sarah Cannon Research Institute

Background: Neoadjuvant chemotherapy for locally advanced breast cancer improves survival and rates of breast-conserving surgery. Pathologic complete response (pCR) after neoadjuvant therapy strongly correlates with improved disease free survival (DFS) and provides an early indicator of treatment efficacy. The expected pCR rate with a standard taxane-containing combination is approximately 18%. Eribulin is a non-taxane synthetic analogue of halichondrin B that inhibits microtubule dynamics by a novel mechanism of action distinct from other tubulin-targeting agents. Eribulin is active against taxane and anthracycline pretreated metastatic breast cancer (MBC) and is well tolerated with a predictable toxicity profile. Substitution of eribulin for docetaxel in a neoadjuvant combination regimen may therefore improve efficacy. This study will evaluate the non-anthracycline eribulin/cyclophosphamide (ErC) and docetaxel/cyclophosphamide (TC) combinations as neoadjuvant therapy. The first ten patients (pts) will be evaluated for tolerability and feasibility of standard prescribed eribulin monotherapy dosing in combination with standard dose cyclophosphamide.

Study Objectives: This randomized phase II trial is designed to determine the pCR rate of locally advanced, HER2-negative breast cancer treated with 6 cycles of ErC or TC. The secondary objectives are to evaluate the clinical response rate of ErC as neoadjuvant therapy and to determine the 2 year DFS of pts treated with ErC and TC.

Eligibility: Females ≥ 18 years with untreated, locally advanced, HER2-negative breast cancer appropriate for neoadjuvant chemotherapy are eligible. Eligibility criteria include: adenocarcinoma histology; clinical T1-3, N0-2, M0 breast tumors; ECOG PS 0–2; known hormone receptor status at study entry; adequate bone marrow and organ function; willingness to provide archived biopsy specimen for correlative testing. Clinical N3, T1N0M0, and T4 tumors are excluded. Upfront axillary lymph node sampling and/or definitive nodal surgery is permitted, and demonstrated pN3a disease is allowed.

Trial Design: A lead-in phase of the trial will enroll 10 pts to be treated with ErC to determine safety and feasibility of the combination. If the safety is confirmed, subsequent pts will be stratified by hormone receptor status (positive vs. triple- negative) and will be randomized in a 2:1 ratio to Arm 1: ErC or Arm 2: TC. Pts on Arm 1 will receive eribulin 1.4 mg/m2 IV (Days 1 & 8) and cyclophosphamide 600 mg/m2 IV (Day 1). Pts on Arm 2 will receive docetaxel 75 mg/m2 IV (Day 1) and cyclophosphamide 600 mg/m2 IV (Day 1). Both regimens are repeated every 21 days for a total of 6 cycles. After completion of neoadjuvant chemotherapy, pts will undergo definitive local surgery, as determined by the treating surgeon. Archival tumor samples and residual tumor tissue at surgery will be collected for biomarker evaluations. A total of 66 pts (Arm 1: 44; Arm 2: 22) will be enrolled to this study. A pCR rate ≥ 18% in patients treated with ErC is considered a study result that merits further evaluation. This trial is pending activation and has a total accrual goal of 76 pts.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr OT3-3-08.

Abstract P6-11-14: Post-hoc safety and tolerability assessment in patients receiving palliative radiation during treatment with eribulin mesylate for metastatic breast cancer

Background: Management of advanced breast cancer frequently includes palliative radiation therapy (RT) and many chemotherapy agents are radiation-sensitizers. We assessed whether the safety profile of eribulin differed between metastatic breast cancer (MBC) patients receiving eribulin alone and those who also received palliative RT.

Methods: Two previous phase 2 and 3 eribulin trials (Studies 211 and 305, respectively) enrolled a total of 794 patients with locally recurrent or MBC who had received 2–5 prior chemotherapy regimens. In both trials eribulin mesylate (1.4 mg/m2) was given on Days 1 and 8 of a 21-day cycle and intercurrent palliative RT was permitted. In this post-hoc analysis, patient-level data were pooled for a descriptive comparison of adverse events (AEs) between the patients who received RT during their study treatment and those who did not. RT delivered within 3 weeks of initiation of eribulin or RT encompassing >30% of marrow was excluded. If palliative RT was utilized on study, the protocol requirements were as follows: indications included bone pain, bronchial obstruction, ulcerating skin lesions; the total field for palliative RT was not to involve >10% of total bone marrow; and the irradiated lesion was not to be used for tumor response assessment. During palliative RT, eribulin treatment was to be delayed and then resumed when the patient had recovered from any RT-associated toxicities.

Results: Of the 794 patients (291 patients in Study 211 and 503 in Study 305) who received eribulin, 44 (5.5%) received palliative RT.

P3-14-29: Neoadjuvant Sunitinib Administered with Weekly Paclitaxel/Carboplatin in Patients with Locally Advanced Triple-Negative Breast Cancer: A Sarah Cannon Research Institute Phase I/II Trial

Background: Angiogenesis plays a substantial role in breast cancer development as well as in triple negative breast cancer (TNBC). Sunitinib is an inhibitor of the tyrosine kinase receptors for VEGF, platelet-derived growth factor (PDGF), KIT, RET, and fms-like tyrosine kinase receptor-3 (FLT3). As monotherapy in heavily pretreated breast cancer patients (pts), sunitinib demonstrated a response rate of 15% in TNBC (11% of all pts) with stable disease or better in 16% of all pts. The combination of paclitaxel and carboplatin is ideally suited for further exploration as neoadjuvant chemotherapy for TNBC, based on the established preclinical and clinical sensitivity of TNBC to these cytotoxic agents. This open label, phase I/II trial was designed to evaluate the combination of sunitinib plus paclitaxel and carboplatin as neoadjuvant treatment for locally advanced breast cancer. The primary objective for the phase I portion was to determine the maximum tolerated dose (MTD); these results are presented. Methods: Women with histologically confirmed invasive triple-negative adenocarcinoma of the breast, (defined as <10% staining by IHC for ER/PR; IHC 0–1+ or FISH negative for HER2), with no evidence of metastatic disease and normal LVEF were eligible. All pts received sunitinib (days 1–28), paclitaxel (days 1, 8, 15), and carboplatin (day 1) in 28-day treatment cycles x6. Following 6 cycles, pts had definitive surgery. After ≥2 weeks and evidence of adequate wound healing, maintenance sunitinib 25mg PO daily was initiated to complete a total of 52 weeks. Three dose levels were evaluated as shown in the table below:

P1-12-10: Phase II Study Evaluating Lapatinib (L) in Combination with Albumin Bound Paclitaxel (ab-Pac) in Women Who Have Received 0–1 Chemotherapy Regimen for HER2 Overexpressing (HER2+) Metastatic Breast Cancer (MBC)

Background: L, a dual kinase inhibitor of epidermal growth factor receptor (EGFR) and the human epidermal growth factor receptor-2 (HER2), approved for the treatment of HER2+ MBC in combination with capecitabine following progression after trastuzumab, anthracycline, and taxane. L in combination with chemotherapy has significantly improved progression free survival in patients (pts) with HER2+ MBC. Ab-Pac is a cremophor free, albumin-bound paclitaxel approved for use in pts with MBC demonstrating superior efficacy and safety when compared to other taxanes.

Methods: Phase II study (LPT111111) evaluated the efficacy and safety of L in combination with ab-Pac in 60 pts with histologically confirmed stage IV HER2+ (IHC 3+/FISH+) invasive MBC. Pts received 0–1 prior chemotherapeutic regimen in the metastatic setting and no prior treatment with L. Prior taxane therapy permitted provided this was > 12 months prior to study entry, LVEF>50%, peripheral neuropathy < 2, prior CNS mets permitted, and prior endocrine therapy permitted. Pts received ab-Pac (125 mg/m2 IV on Days 1, 8, 15, q28 days) plus L (1250 mg daily). Planned safety analysis of the first 5 pts prompted a protocol amendment with a 20% dose reduction for both agents due to Grade (G) 3 neutropenia and diarrhea. Subsequent pts received ab-Pac (100 mg/m2 IV on Day 1, 8, 15, q28 days) in combination with L (1000 mg daily). Pts with SD or a response continued L alone until progression. Response assessments performed every 2 cycles. The primary endpoint was overall response rate (ORR) and secondary endpoints were progression-free survival (PFS), time to response, duration of response and overall survival (OS).

Results: Here we present the final analysis of all subjects receiving at least 6 months of protocol therapy. Median age is 56 years; 45 pts (75%) received treatment as 1st line therapy and 15 (25%) as 2nd line; 57% hormone receptor positive and 43% negative; 42% received trastuzumab and 40% received a taxane in either (neo) adjuvant or metastatic setting. After a median of 5.6 months, 7% pts had a complete response, 47% a partial response and 17% had stable disease, the ORR was 53% [95% CI: 41% to 66%]. The median time to response was 7.8 wks [95% CI: 7.4 to 8.1] with a median duration of response of 48.7 wks [95% CI: 31.7 to 57.1]. The median PFS was 39.7 wks [95% CI: 34.1 to 63.9]. Duration of exposure to ab-Pac; 48% received less than 6 cycles, 30% received 6 cycles and 22% received greater than 6 cycles. Table 1 shows the most common G ≥2 treatment-related toxicities.

P1-08-22: Treatment Patterns and Clinical Outcomes in Elderly Patients with HER2−Positive Metastatic Breast Cancer from the registHER Observational Study

Background: Data are lacking regarding treatment patterns and outcomes in elderly patients (pts) with HER2−positive (HER2+) metastatic breast cancer (MBC).

Methods: registHER is a large, observational cohort of pts with HER2+ MBC diagnosed within 6 months of enrollment. Pts (N=1,001) were followed until death, disenrollment, or June 2009 (median follow-up 27 months). In these analyses, pts were stratified into three groups based on age at MBC diagnosis: younger (<65 years), older (65-74 years), elderly (≥75 years). For Progression Free Survival (PFS) and Overall Survival (OS) analyses of 1st-line trastuzumab (T) vs. no T, older and elderly pts were combined due to small number of events in elderly. Hierarchical multivariate analyses were adjusted for baseline characteristics and treatments.

Results: ER/PR status was similar across age groups (Table 1). Elderly pts with HER2+ MBC had higher rates of underlying cardiovascular disease (CVD) than younger or older pts. In pts receiving T-based 1st-line treatment, elderly pts were less likely to receive chemotherapy (C), and more likely to receive T alone or combined with hormone therapy (HT). Central nervous system (CNS) events decreased with increasing age. In T-treated pts, incidence of left ventricular dysfunction (grade ≥3) was higher in elderly pts (3/63 [4.8%]) than in younger (21/746 [2.8%]) or older pts (2/134 [1.5%]). Across age groups, unadjusted median PFS (months) was significantly higher for pts treated with T in 1st-line than those who were not (<65 years T: 11.0; <65 years no T: 3.4; ≥65 years T: 11.7; ≥65 years no T: 4.8). In pts <65 years, unadjusted median OS (months) was significantly higher in T-treated pts; in pts ≥65 years, median OS was similar (<65 years T: 40.4, <65 years no T: 25.9; ≥65 years T: 31.2, ≥65 years no T: 28.5). In multivariate analyses, T in 1st-line was associated with significant improvement in PFS across age (Table 2). In OS, significant improvement was observed for pts <65 years; results were suggestive for pts ≥65 years.

Conclusions: Elderly pts (≥75 years) with HER2+ MBC in registHER had higher rates of underlying CVD than younger counterparts and received less aggressive treatment, including less 1st-line T. These population-based, real-world data suggest improved PFS with T as 1st-line therapy across all age groups.

OT2-01-03: Eribulin in Women with Locally Advanced Breast Cancer Who Do Not Achieve Pathologic Complete Response (pCR) Following Neoadjuvant Chemotherapy: A Sarah Cannon Research Institute Phase II Trial

Background: Little evidence currently exists to support the use of further therapy for women with localized breast cancer who do not achieve pathologic complete response (pCR) after treatment with standard neoadjuvant chemotherapy. Eribulin is a novel inhibitor of microtubule formation via induction of irreversible cell cycle arrest at G2/M. It retains in vitro activity against cancer cells that are paclitaxel-resistant due to β tubulin mutations, and induces less neuropathy in mice when compared with paclitaxel. Eribulin mesylate was recently approved by the FDA for the treatment of patients with metastatic breast cancer (MBC) who have previously received ≥2 chemotherapeutic regimens for the treatment of metastatic disease. Prior therapy should have included an anthracycline and a taxane in either the adjuvant or metastatic setting.

Study Objectives: This phase II trial is designed to assess the efficacy of eribulin mesylate in women with localized breast cancer who do not achieve pCR following standard neoadjuvant chemotherapy (+ trastuzumab in HER2−positive tumors). The primary endpoint is 2-year disease-free survival (DFS). The secondary goal of this trial is to assess the feasibility of the administration of 6 post-operative cycles of eribulin in patients (pts) who have received neoadjuvant chemotherapy.

Eligibility: Women aged ≥18 years with a histological diagnosis of invasive breast cancer (T1-3, N1-2, M0) who have received ≥4 cycles of anthracycline and/or taxane containing neoadjuvant chemotherapy regimen (+trastuzumab in HER2−positive tumors) are eligible. Pts must have failed to achieve a pCR following neoadjuvant treatment (i.e. residual invasive breast cancer (>5mm) in the breast or lymph nodes at surgery [ypT1b-T4, N1-N2, M0]). Additional eligibility criteria include: ECOG performance status of 0–1; adequate hematologic, hepatic and renal function. Pts with nonhealed surgical wounds, known or active cardiovascular disease, QTc interval > 480 msecs, chronic use of QTc prolonging drugs, as well as previous breast cancer diagnosis <3 years prior to trial entry, are excluded.

Trial Design: Pts are stratified into three cohorts according to HER2 and hormone receptor status as follows: triple-negative (Cohort A, n=54), hormone-receptor positive/HER2−negative (Cohort B, n=42) and HER2−positive (Cohort C, n=52). All pts receive eribulin mesylate 1.4mg/m2 IV on days 1&8 of each 21-day treatment cycle for 6 cycles. Pts with HER2−postive tumors also receive trastuzumab 6mg/kg IV day 1 of each cycle. Locoregional radiotherapy and/or adjuvant hormonal therapy (Cohort B only) will be administered per institutional guidelines. With standard neoadjuvant therapy, the approximate 2-year DFS of pts who do not achieve pCR are as follows: triple-negative, 40%; hormone-receptor-positive/HER2−negative, 80%; and HER2−positive, 60%. For a one-sided test of hypothesis at alpha = 0.10 and power = 0.80, the required numbers of evaluable patients treated in each cohort are 49, 38, and 47, respectively, to demonstrate improvement in treatment outcome in these groups of at-risk pts.

The trial is currently enrolling and has an accrual goal of 148 patients.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT2-01-03.

P1-07-02: Discordance between Central and Local Laboratory HER2 Testing from a Large HER2−Negative Population in VIRGO, a Metastatic Breast Cancer Registry

Background: HER2 overexpression is associated with unfavorable prognosis and is reported in 18–25% of breast cancers (BC). HER2 testing is often performed using immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH). Because of the significant benefit of HER2−directed therapies, it is critical to accurately identify women whose tumors are HER2+. Reports have noted discordance between HER2+ test results from local vs. large reference labs in patients with HER2+ BC evaluated for trastuzumab-based clinical studies. There are little published data on central testing of BC found to be negative locally.

Patients and Methods: VIRGO is an observational cohort of N=1,287 women with primarily HER2−negative metastatic BC. An optional tissue collection substudy was conducted, and 776 patient samples were received and centrally retested. Central testing was performed at 2 reference labs and tumors were deemed HER2+ if IHC 3+ and/or FISH positive (HER2:CEP17 ratio ≥2.0). Tumors with unknown/missing local HER2 status (n=68) were excluded from primary analyses. Number of patients potentially affected based on BC incidences from the American Cancer Society (ACS) 2011 estimates and the World Health Organization (WHO) 2008 report were calculated. Testing on the remainder of the HER2−negative cohort is in process.

Results: Central retesting has been performed on tumor samples from n=373 patients to date: HER2−negative locally evaluable tumors (n=301), n=4 HER2−negative locally with no evaluable tumor, and HER2 unknown (n=68). A total of 301 unique patient samples were included in the primary analysis. Of these, 15 (4.98% [95% CI (2.7%, 7.9%)] were found to be HER2+ by central testing (Table). Based on sensitivity analyses assuming all 68 tumors with unknown HER2 status to be negative locally, 4.07%(15 /369) would be centrally HER2+.

Results of ENCORE 301, a randomized, phase II, double-blind, placebo-controlled study of exemestane with or without entinostat in postmenopausal women with locally recurrent or metastatic estrogen receptor-positive (ER+) breast cancer progressing on a nonsteroidal aromatase inhibitor (AI)

268

Background: Hormonal therapy, including AIs, is the mainstay of ER+ breast cancer (BC) treatment; however, both acquired and intrinsic resistance limits its clinical benefit. Entinostat is a novel, oral, class I selective histone deacetylase inhibitor that has been shown to inhibit growth factor signaling pathways that mediate AI resistance. This study was designed to evaluate the impact of the addition of entinostat to exemestane therapy on progression-free survival (PFS).

Methods: Postmenopausal women with ER+ advanced BC who had progressed on a non-steroidal AI were randomized to exemestane 25 mg daily + entinostat 5 mg or placebo weekly.

Results: A total of 130 women were enrolled (66 exemestane+placebo; 64 exemestane+entinostat). All but 1 patient had Stage IV disease, and 82% had measurable disease. All patients had received prior hormonal therapy (1 prior line 42%; >1 prior line 58%), and 62% had received prior chemotherapy (33% in the advanced BC setting). Analysis of the intent-to-treat population showed that PFS was significantly (defined prospectively as p <0.10) longer with exemestane+entinostat than with exemestane+placebo (4.28 versus 2.27 months, respectively; hazard ratio [HR] = 0.73; p=0.06). Entinostat combined with exemestane was well-tolerated with the most frequent adverse events (AEs) consisting of fatigue, gastrointestinal disturbances, and hematologic abnormalities. AEs with a ≥20% higher incidence with exemestane+entinostat than with exemestane+placebo were fatigue (46% versus 26%, respectively) and uncomplicated neutropenia (25% versus 0%, respectively). The serious AE rate was similar for exemestane+entinostat (13%) and exemestane+placebo (12%).

Conclusions: Exemestane+entinostat significantly prolonged the median PFS and reduced the risk of disease progression by 27% versus exemestane+placebo (HR = 0.73). In light of these positive data, a phase III evaluation of this combination is planned.

Bevacizumab (BEV) plus second-line taxane (TAX) or other chemotherapy (CT) for triple-negative breast cancer (TNBC): Subgroup analysis of RIBBON-2

290

Background: In three randomized trials in the first-line metastatic breast cancer (MBC) setting, combining BEV with CT significantly improved progression-free survival (PFS; primary endpoint) and objective response rate (ORR) vs. CT alone. BEV also showed a significant PFS benefit in the second-line MBC setting (RIBBON-2) when combined with TAX or other CT. We analyzed data from the subgroup of patients (pts) with TNBC in RIBBON-2.

Methods: Eligible pts had MBC that had progressed on first-line CT without BEV. Second-line CT (TAX, gemcitabine, capecitabine, or vinorelbine) was chosen before 2:1 randomization to CT with either BEV (10 mg/kg q2w or 15 mg/kg q3w) or placebo (PLA). All pts could receive BEV at progression. The primary endpoint was PFS.

Results: RIBBON-2 included 684 pts; 159 (23%) had TNBC and of these, 67 (42%) received TAX with BEV/PLA. Baseline characteristics were broadly similar in the two treatment arms. In an exploratory analysis of pts with TNBC, BEV + CT led to significantly improved PFS and ORR vs. CT alone, and a trend toward improved overall survival (OS). The magnitude of the effect was particularly pronounced in pts receiving TAX CT.

Conclusions: Pts with TNBC derive significant ORR and PFS benefit from BEV combined with second-line CT. Despite the small sample size, there was a trend (HR 0.624; p = 0.0534) toward OS benefit in pts treated with BEV, especially with TAX CT.

[Table: see text]

Abstract P5-06-06: The Safety and Tolerability of Panobinostat (LBH589) in Combination with Capecitabine +/− Lapatinib: A Phase I Study in HER2+ Breast Cancer

Background: Panobinostat is a histone deacetylase (HDAC) inhibitor, for which in vitro studies have suggested activity in breast cancer lines. This phase I study was designed to assess the safety, tolerability, and efficacy of panobinostat in combination with lapatinib and capecitabine in 3 parts. Part 1, for which we have previously reported findings (Peacock et al, ASCO 2010), established the maximum tolerated dose (MTD) of panobinostat (30mg twice weekly) in combination with capecitabine (1000mg/m2 BID). Part 2, reported here, was designed to assess the QTc prolongation and overall toxicity of panobinostat in combination with lapatinib in patients with HER2+ breast cancer. Part 3 will assess the tolerability and efficacy of the triplet combination based on doses defined in Parts 1 and 2. Method: Patients aged ≥18 years with incurable, locally recurrent or metastatic HER2+ breast cancer were eligible. Additional eligibility criteria included: &lt; 3 prior treatments in the metastatic setting; ECOG PS 0-1; measurable disease by RECIST; no impairment of cardiac function; no prior treatment with HDAC inhibitors; informed consent. Lapatinib doses of 1000mg daily were administered with panobinostat doses of 15mg and 20mg three times weekly, following 1 week of 2 doses of panobinostat alone to assess QTc prolongation. Cycles were repeated every 21 days until disease progression or toxicity warranted drug discontinuation. Patients were reevaluated for response every 2 cycles.

Results: 5 female patients with HER2+ metastatic breast cancer were accrued to Part 2, with a median age of 66 years (range: 64 — 67); 80% of patients were ECOG PS 0. To date, patients have received 17 cycles of treatment (median 4 cycles), and 2 patients have stable disease (progression1, unevaluable 1, and too early to assess 1), with one patient remaining on treatment. There have been no dose-limiting toxicities. One patient was hospitalized for grade 3 peripheral neuropathy (unrelated). No grade 2/3/4 toxicities have occurred in &gt;1 patient; no QTc prolongation has been observed.

Conclusions: Our preliminary findings suggest that the combination of panobinostat and lapatinib is safe and tolerable. No QTc prolongation or cardiotoxicity has been observed. Part 3 will evaluate the triplet combination using the dosages established in Parts 1 and 2.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-06-06.

Phase III trial of sunitinib (SU) in combination with capecitabine (C) versus C in previously treated advanced breast cancer (ABC)

LBA1011

Background: Recent trials support combining an antiangiogenic agent with chemotherapy (CT) in pretreated patients (pts) with metastatic BC (MBC). SU, an oral multitargeted tyrosine kinase inhibitor demonstrated single-agent activity (11% ORR) in heavily pretreated pts with MBC. Antitumor activity with SU+C was reported in pts with advanced solid tumors. This multicenter, randomized, phase III trial (SUN 1099) compared the efficacy and safety of SU + C vs. C in pts with ABC.

Methods: Eligibility criteria were: age ≥18 yrs, ECOG PS ≤1, measurable HER2-positive (FISH+, CISH+ or IHC3+) or -negative ABC, no brain metastases, prior treatment (tx) with an anthracycline and taxane in the (neo)adjuvant or metastatic setting, and ≤2 prior CT regimens for advanced disease. Prior C tx was not permitted. Pts were randomized (1:1) to combination tx with C 2,000 mg/m2/d po days 1–14 every q3w + SU 37.5 mg/d po daily, or to C 2,500 mg/m2/d days 1–14 q3w. Pts with progressive disease per RECIST on the C arm were offered single-agent SU (37.5 mg/d). Endpoints included PFS (primary), ORR, OS, QoL, and safety. Stratified and unstratified log-rank tests compared PFS between arms.

Results: At the data cutoff (December 15, 2009), the ITT population comprised 442 pts: 221 in each arm with baseline characteristics well balanced between arms. The trial did not meet its primary endpoint of prolonging PFS based on the independent radiologic assessment nor secondary endpoint of longer OS (final analysis March 10, 2010). Median PFS was 5.5 mos (95% CI 4.5–6.0) in the SU+C arm vs. 5.9 mos (95% CI 5.4–7.6) in the C arm (HR 1.224). Median OS was 16.4 mos (95% CI 13.6–18.4) for the SU+C arm and 16.5 mos (95% CI 14.2–18.6) for the C arm (HR 0.995). ORR was 18.6% for the SU+C arm and 16.3% for the C arm. The most common all causality grade 3/4 AEs (≥10%) were neutropenia (32%), hand–foot syndrome (HFS; 16%), thrombocytopenia (17%), asthenia (12%), fatigue (10%) in the SU+C arm and HFS (24%) and diarrhea (10%) in the C arm. Intended drug delivery for each arm was >80%. Discontinuations due to an AE were more frequent in the SU+C arm vs. the C arm. Discontinuations by drug in the SU+C arm: SU 39%, C 42%, SU and C 33%; in the C arm: 18%.

Conclusions: Data from this randomized phase III trial do not support use of SU+C for therapy of patients with ABC.

[Table: see text]