Sacituzumab govitecan, a Trop-2-directed antibody-drug conjugate, for patients with epithelial cancer: final safety and efficacy results from the phase I/II IMMU-132-01 basket trial

BACKGROUND

Sacituzumab govitecan (SG), a trophoblast cell surface antigen-2 (Trop-2)-directed antibody-drug conjugate, has demonstrated antitumor efficacy and acceptable tolerability in a phase I/II multicenter trial (NCT01631552) in patients with advanced epithelial cancers. This report summarizes the safety data from the overall safety population (OSP) and efficacy data, including additional disease cohorts not published previously.

PATIENTS AND METHODS

Patients with refractory metastatic epithelial cancers received intravenous SG (8, 10, 12, or 18 mg/kg) on days 1 and 8 of 21-day cycles until disease progression or unacceptable toxicity. Endpoints for the OSP included safety and pharmacokinetic parameters with investigator-evaluated objective response rate (ORR per RECIST 1.1), duration of response, clinical benefit rate, progression-free survival, and overall survival evaluated for cohorts (n > 10 patients) of small-cell lung, colorectal, esophageal, endometrial, pancreatic ductal adenocarcinoma, and castrate-resistant prostate cancer.

RESULTS

In the OSP (n = 495, median age 61 years, 68% female; UGT1A1∗28 homozygous, n = 46; 9.3%), 41 (8.3%) permanently discontinued treatment due to adverse events (AEs). Most common treatment-related AEs were nausea (62.6%), diarrhea (56.2%), fatigue (48.3%), alopecia (40.4%), and neutropenia (57.8%). Most common treatment-related serious AEs (n = 75; 15.2%) were febrile neutropenia (4.0%) and diarrhea (2.8%). Grade ≥3 neutropenia and febrile neutropenia occurred in 42.4% and 5.3% of patients, respectively. Neutropenia (all grades) was numerically more frequent in UGT1A1∗28 homozygotes (28/46; 60.9%) than heterozygotes (69/180; 38.3%) or UGT1A1∗1 wild type (59/177; 33.3%). There was one treatment-related death due to an AE of aspiration pneumonia. Partial responses were seen in endometrial cancer (4/18, 22.2% ORR) and small-cell lung cancer (11/62, 17.7% ORR), and one castrate-resistant prostate cancer patient had a complete response (n = 1/11; 9.1% ORR).

CONCLUSIONS

SG demonstrated a toxicity profile consistent with previous published reports. Efficacy was seen in several cancer cohorts, which validates Trop-2 as a broad target in solid tumors.

Sacituzumab govitecan in previously treated hormone receptor-positive/HER2-negative metastatic breast cancer: final results from a phase I/II, single-arm, basket trial

BACKGROUND

Trophoblast cell-surface antigen-2 (Trop-2) is expressed in epithelial cancers, including hormone receptor-positive (HR+) metastatic breast cancer (mBC). Sacituzumab govitecan (SG; Trodelvy®) is an antibody-drug conjugate composed of a humanized anti-Trop-2 monoclonal antibody coupled to SN-38 at a high drug-to-antibody ratio via a unique hydrolyzable linker that delivers SN-38 intracellularly and in the tumor microenvironment. SG was granted accelerated FDA approval for metastatic triple-negative BC treatment in April 2020.

PATIENTS AND METHODS

We analyzed a prespecified subpopulation of patients with HR+/human epidermal growth factor receptor 2-negative (HER2-) HR+/HER2- mBC from the phase I/II, single-arm trial (NCT01631552), who received intravenous SG (10 mg/kg) and whose disease progressed on endocrine-based therapy and at least one prior chemotherapy for mBC. End points included objective response rate (ORR; RECIST version 1.1) assessed locally, duration of response (DOR), clinical benefit rate, progression-free survival (PFS), overall survival (OS), and safety.

RESULTS

Fifty-four women were enrolled between 13 February 2015 and 1 June 2017. Median (range) age was 54 (33-79) years and all received at least two prior lines of therapy for mBC. At data cut-off (1 March 2019), 12 patients were still alive. Key grade ≥3 treatment-related toxicities included neutropenia (50.0%), anemia (11.1%), and diarrhea (7.4%). Two patients discontinued treatment due to treatment-related adverse events. No treatment-related deaths occurred. At a median follow-up of 11.5 months, the ORR was 31.5% [95% confidence interval (CI), 19.5%-45.6%; 17 partial responses]; median DOR was 8.7 months (95% CI 3.7-12.7), median PFS was 5.5 months (95% CI 3.6-7.6), and median OS was 12 months (95% CI 9.0-18.2).

CONCLUSIONS

SG shows encouraging activity in patients with pretreated HR+/HER2- mBC and a predictable, manageable safety profile. Further evaluation in a randomized phase III trial (TROPiCS-02) is ongoing (NCT03901339).

TRIAL REGISTRATION

ClinicalTrials.gov NCT01631552; https://clinicaltrials.gov/ct2/show/NCT01631552.

Abstract P2-11-01: Safety and efficacy of sacituzumab govitecan (anti-Trop-2-SN-38 antibody-drug conjugate) as ≥3rd-line therapeutic option for treatment-refractory HER2-negative metastatic breast cancer (HER2Neg mBC)

Background: Sacituzumab govitecan is an antibody-drug conjugate consisting of SN-38, the active metabolite of irinotecan, conjugated to a humanized mAb targeting Trop-2 (trophoblastic antigen-2), which is highly expressed in many epithelial cancers. A phase I/II basket trial (NCT01631552) investigated its activity in patients (pts) with advanced epithelial cancers. Herein, we summarize pooled safety and efficacy findings in 162 pts with HER2-negative metastatic breast cancer (mBC) accrued between 7/2013 and 6/2017 who received at least 2 prior therapies for metastatic disease and were treated with sacituzumab govitecan at the 10 mg/kg dose level.

Methods: Patients with triple-negative (N=108) and patients with hormone-receptor positive (N=54) mBC received 10 mg/kg sacituzumab govitecan on days 1 & 8 of a 21-day cycle continued until progression or unacceptable toxicity. All pts had measurable disease by CT or MRI. Efficacy was assessed locally by RECIST 1.1 including overall response rate (ORR) and Kaplan-Meier estimates of duration of response (DOR), progression-free survival (PFS) and overall survival (OS). Adverse events (AE) were evaluated according to CTCAE v4.0

Results: The patient cohort (161 female /1 male; median age 55 yrs, range 31-80) received a median of 4 prior therapies for metastatic disease (range 2-17), with prior chemotherapy agents in the metastatic setting including taxane (68%), capecitabine (60%), platinum (59%), gemcitabine (44%), eribulin (41%), and anthracycline (38%). 77 pts have died, with 57 in long-term follow-up and 28 still on treatment at data cutoff. The median number of administered sacituzumab govitecan doses was 14 (range 1-88). Treatment was generally well tolerated. 29% of pts had dose reductions, 3% discontinued treatment due to drug-related AEs, and there were no treatment-related deaths. Based on currently available AE data, grade ≥ 3 toxicity included neutropenia (43%), anemia (9.5%), diarrhea (7.0%) and febrile neutropenia (6.3%). For the TNBC subgroup, with a median follow-up of 9.3 months, the ORR was 33% (3 CRs + 33 PRs /108) with a median DOR of 8.3 months (95% CI: 4.8 – 11.6). For the ER+ subgroup, with a median follow-up of 10.0 months, the ORR was 31% (17 PRs/54) with a median DOR of 7.4 months (95% CI: 4.4 – 18.3). The combined HER2Neg ORR was 33% (3 CRs+50 PRs/162), with a median DOR of 8.3 months (95% CI: 4.9 - 10.8), PFS of 5.6 months (95% CI: 5.1 – 6.9) and OS of 13.0 months (95% CI: 11.5 - 15.0). The ORR was comparable for pts ≤ 50 yrs. old [32.2% (19/59)] vs. > 50 yrs old [33.0% (34/103)] and little different for pts with 2 prior therapies [35.4% (17/48)] vs. >2 prior therapies [31.6% (36/114)].

Conclusions: Monotherapy with sacituzumab govitecan was well tolerated with a manageable safety profile, and achieved a 30+% objective response rate among heavily pre-treated patients with HER2-negative metastatic breast cancer regardless of ER status.

Citation Format: Kalinsky K, Isakoff SJ, Tolaney SM, Juric D, Mayer IA, Vahdat LT, Diamond JR, O'Shaughnessy J, Moroose RL, Santin AD, Shah NC, Abramson V, Goldenberg DM, Sharkey RM, Washkowitz SA, Wegener WA, Iannone R, Bardia A. Safety and efficacy of sacituzumab govitecan (anti-Trop-2-SN-38 antibody-drug conjugate) as ≥3rd-line therapeutic option for treatment-refractory HER2-negative metastatic breast cancer (HER2Neg mBC) [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 P2-11-01.

Abstract PD9-07: A phase II study of copper-depletion using tetrathiomolybdate (TM) in patients (pts) with high risk breast cancer (BC): Role of collagen processing and tumor microenvironment

Background: Copper is an important catalytic cofactor in several biological functions and is essential for lysyl oxidase (LOX), a key enzyme in cross-linking collagen, which may play a role in tumor metastasis. We hypothesized that tetrathiomolybdate (TM)-associated copper depletion (CD) would inhibit tumor metastases by altering copper dependent collagen remodeling in the pre-metastatic niche. These results are an update of our previously reported clinical outcomes with longer follow-up and translational outcomes implicating the tumor microenvironment in metastatic transformation of BC. Methods: Pts at high risk for recurrence, node+ triple negative (TNBC) or stage 3/4 BC with no evidence of disease (NED), were enrolled on a phase II study of CD with TM. TM was given to maintain ceruloplasmin (Cp) levels between 8-16 mg/dl for two years (yrs) with an extension phase or until relapse. Median Cp levels were monitored with each cycle. Clinical endpoints included safety/tolerability and progression of disease (POD)/death. Event-free (EFS) and overall survival (OS) were calculated using Kaplan Meier survival analyses. Translational endpoints included markers of collagen cross-linking (LOXL-2), formation (PRO-C3), and degradation (C1M and C6M). Results: Seventy-five pts received 2993 cycles of TM on the primary (24 cycles, 28 days per cycle) and extension study. Median age was 51 yrs (range 29-66). Forty-five pts had stage 2/3 BC, and 30 pts were stage 4 NED. At a median follow-up of 8.4 yrs, the overall EFS was 71.4% and OS was 78.8%. The EFS and OS for the 36 pts with TNBC were 71.7% and 81%, and the EFS and OS for the 39 pts with Luminal/HER2+ BC were 71.2% and 78.6% respectively. TM was well tolerated with grade 3/4 toxicities including: neutropenia (1.9%), febrile neutropenia (0.03%), and fatigue (0.2%). LOXL2 levels were significantly decreased at 12 and 24 cycles compared with baseline (p<0.01) in those who were NED but not in those who had progressive disease (POD). LOXL2 levels were significantly correlated with C1M levels (spearman coefficient -0.34, p=0.02). C1M levels were significantly increased at 5, 11 and 24 cycles as compared with baseline (p<0.01) in those who were NED and were significantly higher as compared to levels in those experiencing POD/death, p<0.05. This difference may be more pronounced in those not achieving adequate CD (<50%) and in luminal/HER2+ BC. Interestingly, the ratio of C1M/PRO-C3 was significantly more elevated over time in those NED as compared to those experiencing POD/death. No associations were found with other collagen markers (PRO-C3 and C6M). Conclusions: TM is safe, well-tolerated and associated with decreased LOXL-2 and increased C1M levels over time in NED pts. This suggests that copper depletion may result in decreased collagen crosslinking and increased collagen degradation over formation, potentially “normalizing” the collagen microenvironment to create an inhospitable environment for tumor metastases. Larger randomized trials in high risk populations with translational outcomes are needed to further investigate the role of collagen processing in the tumor microenvironment and its potential as a biomarker of response.

Citation Format: Liu YL, Bager CL, Willumsen N, Kornhauser N, Cobham M, Andreopoulou E, Cigler T, Moore A, LaPolla D, Fitzpatrick V, Ward M, Warren JD, Mittal V, Vahdat LT. A phase II study of copper-depletion using tetrathiomolybdate (TM) in patients (pts) with high risk breast cancer (BC): Role of collagen processing and tumor microenvironment [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 PD9-07.

Abstract P1-11-15: Chemotherapy-induced peripheral neuropathy in breast cancer survivors: Comparison of objective and subjective measures

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a common, potentially debilitating, and dose-limiting side effect experienced by breast cancer survivors. CIPN encompasses symptoms such as pain, numbness, and tingling, which can be measured subjectively by patient-reported outcomes (PRO), or objectively by quantitative sensory testing (QST); however, little is known how QST correlates with symptom profiles measured by PRO.

Methods: We conducted a cross-sectional analysis using baseline data of two ongoing clinical trials of breast cancer survivors who experienced moderate to severe CIPN defined by pain, numbness, or tingling ratings of four or greater on a numeric rating scale (NRS) after chemotherapy completion for at least three months. PRO measures of CIPN symptoms included Neuropathic Pain Scale (NPS) and Functional Assessment of Cancer Therapy-Gynecologic Oncology Group/Neurotoxicity subscale (FACT/GOG-Ntx). QST included tactile threshold (TT) measured by Von Frey's filaments, and vibration threshold (VT) measured by biothesiometer. We ran a Spearman correlation to assess the relationship between the subjective measures (NPS and FACT/GOG-Ntx) and objective measures (TT and VT QST).

Results: We included 52 sets of baseline data on 50 unique patients; two patients were enrolled in both trials at different times. Mean age was 61 years (SD 10) and 66% were white. The mean NRS pain score was 3.9 (SD 2.8), numbness 5.7 (SD 2.2), and tingling 4.3 (SD 2.8) on a 0-10 scale. The mean NPS total score was 39.2 (SD 23.1) on a 0-100 scale, and FACT/GOG-Ntx was 26.2 (SD 6.8) on a 0-44 scale. High scores on NRS and NPS and low scores on FACT/GOG-Ntx signify more severe CIPN symptoms. See Table 1 for a summary of the correlation between two questions on FACT/GOG-Ntx on tingling/numbness in hands and feet, and NPS total score with QST. A moderate correlation was observed between FACT/GOG-Ntx and QST results, suggesting patient-reported hand and foot numbness or tingling is associated with decreased hand and foot tactile and vibration perception. NPS was positively correlated with tactile perception for the hand and foot, but not with vibration perception.

Table 1.Correlation between objective and subjective measures of CIPN Tactile QSTVibration QST HandFeetHandFeetFACT/GOG-Ntx-0.33 (P=0.018)-0.28 (P=0.045)-0.37 (P=0.008)-0.40 (P=0.0034)NPS0.34 (P=0.015)0.32 (P=0.022)0.22 (P=0.12)0.03 (P=0.81)

Conclusions: A mild to moderate correlation was observed between subjective and objective measurements of CIPN. As CIPN presents a diverse range of symptoms, better quantifying the subjective and objective measures of CIPN can help incorporate these tools in observational and intervention trials. Understanding the correlation between PRO and QST can help establish QST as a reliable objective measurement of CIPN symptoms, and enable targeted interventions to alleviate CIPN symptoms.

Citation Format: Bao T, Kwon A, Piulson L, Chen P, Li Q, Patil S, Seidman A, Blinder V, Vahdat L, Zhi WI, Mao JJ. Chemotherapy-induced peripheral neuropathy in breast cancer survivors: Comparison of objective and subjective measures [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 P1-11-15.

Abstract PD1-02: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Cortes J, Martin M, Pernas S, Gomez Pardo P, Lopez-Tarruella S, Gil-Martin M, Manso L, Ciruelos E, Perez-Fidalgo JA, Hernando C, Ademuyiwa FO, Weilbaecher K, Mayer I, Pluard TJ, Martinez Garcia M, Vahdat L, Wach A, Barker D, Romagnoli B, Kaufman PA. Withdrawn [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 PD1-02.

Abstract P1-10-10: Tumor infiltrating lymphocytes (TILS) among high risk for recurrence breast cancer patients treated with tetrathimolybdate (TM)

Background: Tumor infiltrating lymphocytes (TILs) evaluated in the primary tumor biopsy or surgical resection have been well established as having prognostic significance in patients with triple negative breast cancer (TNBC) and HER2+ breast cancer treated with adjuvant chemotherapy (Savas et. al, Nat Rev Clin Oncol 2016). In TNBC, stromal TILs behave as a continuous variable with every 10% increase in TIL resulting in a decrease in risk of recurrence and death. The definition of lymphocyte-predominant breast cancer (LPBC) has been used for tumors that contain 50%–60% TILs and usually have a particularly good outcome (Salgado et al, Ann Oncol 2015). Our group recently demonstrated in a phase II single arm study that tetrathimolybdate (TM), a copper-depleting agent, resulted in improved event free survival (EFS) for TNBC patients compared to historical controls. The 2-year event-free survival (EFS) for stage 2-3 and stage 4 NED was 91% and 67%, respectively. In this analysis, our goal was to explore whether the encouraging results we observed were influenced by enrolling TNBC patients with better prognostic factors at initial diagnosis, namely higher stromal TIL score, in our copper depletion trial.

Methods: Archived primary breast tissue was available from 67 of the 75 patients enrolled in the phase II TM trial. The phase II study included patients with stage II TNBC or stage III or IV NED breast cancer patients, who were treated with TM for 2 years or until relapse. Here we focused on the 30 patients with TNBC. The demographic data for the patients is included in the following table.

Patient DemographicsAge at diagnosisStage at study entryPrior Adjuvant or Neoadjuvant therapyNumber of prior chemotherapy regimens in metastatic setting%Tumor Infiltrating Lymphocytes504Adjuvant110543AAdjuvantn/a30563AAdjuvantn/a20513CNeoadjuvantn/a<5454Adjuvant230514Neoadjuvant210363CAdjuvantn/a20592BAdjuvantn/a60453CAdjuvantn/a<5544Adjuvant130443CNeoadjuvantn/a20474Adjuvant020563CNeoadjuvantn/a10512AAdjuvantn/a10583AAdjuvantn/a20654None25513CNeoadjuvantn/a50503CNeoadjuvantn/a30543CNeoadjuvantn/a10542AAdjuvantn/a20403CNeoadjuvantn/a40604Adjuvant160564None160554Adjuvant010633CNeoadjuvantn/a5424Adjuvant050454Adjuvant110463AAduvantn/a10523CNeoadjuvantn/a10514Adjuvant1<5

The number of TILs in each sample was calculated by an experienced pathologist using published criteria (Salgado et al, Ann Oncol 2015). We used TILs >50% to define LPBC.

Results: Overall, we found that only 3/30 (10%) of TNBC patients had TILs >50%. In addition, 14/30 (46.7%) of TNBC patients had tumors with <10% TILs. The 2-year EFS for the patients with TILs >10% v. <10% was 76.9% v. 69.8%, respectively. (P=0.65)

Conclusions: Only 10% of TNBC patients enrolled in the study had LPBC at diagnosis thus indicating that this cohort was not enriched for patients with immunogenic tumors. When stratified by TILs >10% or <10%, there was no statistically significant difference in EFS. Although the analysis is limited due to the small sample size, it does suggest that the amount of TILs present at initial diagnosis did not influence the overall outcome for patients treated with TM.

Citation Format: Rybstein MD, Nackos E, Kornhauser N, Cigler T, Andreopoulou E, Moore A, Cobham M, Fitzpatrick V, Demaria S, Vahdat LT. Tumor infiltrating lymphocytes (TILS) among high risk for recurrence breast cancer patients treated with tetrathimolybdate (TM) [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 P1-10-10.

Abstract P1-10-02: A phase II study of copper-depletion using tetrathiomolybdate in patients with breast cancer at high risk for recurrence: Updated results

Background: Metals have emerged as a viable therapeutic target for a new generation of anti-cancer and anti-metastatic agents. Copper, an essential trace element, serves as an important catalytic cofactor in several biological functions and has emerged as an essential factor in carcinogenesis. Among other elements, bone marrow derived VEGFR2+ endothelial progenitor cells (EPCs) and copper-dependent lysyl oxidase (LOX) are key elements in tumor progression. We hypothesized tetrathiomolybdate (TM)-associated copper depletion (CD) inhibits tumor metastases by reducing the number of EPCs and other copper dependent processes in the pre-metastatic niche. These results are an update of our previously reported study (Chan N, Willis A, Kornhauser N et al. Influencing the Tumor Microenvironment: Phase 2 Study of Copper Depletion with Tetrathiomolybdate in High Risk Breast Cancer and Preclinical Models of Lung Metastases. Clin Cancer Res. October 21, 2016) with longer follow-up.

Methods: A single arm phase II study of breast cancer (BC) patients (pts) at high risk for recurrence, defined as node+ triple negative (TNBC), stage 3 and 4 with no evidence of disease (NED) were enrolled on a trial of CD with TM. TM was given to maintain ceruloplasmin (Cp) levels between 8-16 mg/dl for two years with an extension phase or until relapse. The primary endpoint was a change in EPCs measured by flow cytometry before and during treatment. Secondary endpoints included tolerability, safety, PFS and LOXL-2 levels.

Results: Seventy-five pts received 2778 cycles of TM on the primary and extension study. The primary study treatment duration was 24 cycles (each cycle is 28 days) plus an extension phase. The median age is 51 years (range 29-66). Forty-five pts have stage 2/3 BC and 30 with stage 4 NED. Forty-eight percent of pts are TNBC and 40% of pts are stage 4 NED. Median Cp levels were monitored with each cycle. A decrease from 28 to 16 (p<0.0001) was seen after one cycle. Interestingly, TNBC pts seemed to have a greater decrease from 23.5 to 13 after one cycle. TM was well tolerated with grade 3/4 toxicities including: reversible neutropenia (2.3%), febrile neutropenia (0.04%), fatigue (0.2%). Five-year analysis showed a decrease in EPC's (p=0.004) and LOXL-2 (p<0.001). At a median follow-up of 7.1 years, the EFS for 75 pts is 71.4%. The EFS for 36 pts with TNBC is 71.7%. EFS for stage 2/3 TNBC is 83% and for stage IV TNBC is 59.3%.

Conclusions: TM is safe, well tolerated and appears to affect multiple components of the tumor microenvironment that have been identified in pre-clinical models as important for progression. Ongoing studies in banked specimens are underway to further delineate its effect on copper dependent processes necessary for metastases. Randomized trials are warranted, especially in patients who are at high risk for relapse such as those with TNBC.

Citation Format: Sahota S, Willis A, Kornhauser N, Ward M, Cobham M, Cigler T, Moore A, Andreopoulou E, Fitzpatrick V, Schneider S, Prima N, Wiener A, Ko D, De Laurentiis A, Warren JD, Rubinchik A, Mittal V, Vahdat LT. A phase II study of copper-depletion using tetrathiomolybdate in patients with breast cancer at high risk for recurrence: Updated results [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 P1-10-02.

Abstract P1-12-01: Withdrawn

This abstract was withdrawn by the authors.

Abstract P3-15-03: Clinical benefit, toxicity, and cost of metastatic breast cancer drug therapies: Visualizing randomized and non-randomized evidence

Background: Given the rapidly expanding size of the clinical trial literature for metastatic breast cancer (MBC) clinical trials, oncologists need tools that enable them to efficiently review the settings and results of previous studies.

Methods: We searched the Cochrane Central Register of Controlled Trials and PubMed to identify clinical trials testing MBC drug therapies. Key eligibility criteria included >90% of patients enrolled in trial having MBC, therapeutic clinical trials, and Phase II or III studies with at least 10 patients at a dosage level. From each study, we extracted information about clinical benefit and toxicity of drug therapies, and we further estimated the costs of all drug therapies. We built a web-based visualization tool that presents the results of all studies testing a given drug combination, stratified based on patients' receptor statuses and prior exposure to therapy. The tool presents both aggregate and study-level results, and reports both unadjusted study results and standardized results based on key patient characteristics in the study populations.

Results: We included 1,783 studies containing 2,549 treatment arms and 170,515 patients in the visualization tool. The tool reports information on 77 HER-2-directed therapies, 101 hormonal therapies, and 675 undirected therapies. The visualization tool has been made publicly accessible for patients and doctors to access at http://cancertrials.info.

Discussion: We believe this tool will make literature reviews significantly more efficient for oncologists, enabling them to better leverage insights from the clinical trial literature when making treatment decisions.

Citation Format: Silberholz J, Vahdat L, Bertsimas D. Clinical benefit, toxicity, and cost of metastatic breast cancer drug therapies: Visualizing randomized and non-randomized evidence [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 P3-15-03.

Hybrid capture-based genomic profiling of circulating tumor DNA from patients with estrogen receptor-positive metastatic breast cancer

BACKGROUND

Genomic changes that occur in breast cancer during the course of disease have been informed by sequencing of primary and metastatic tumor tissue. For patients with relapsed and metastatic disease, evolution of the breast cancer genome highlights the importance of using a recent sample for genomic profiling to guide clinical decision-making. Obtaining a metastatic tissue biopsy can be challenging, and analysis of circulating tumor DNA (ctDNA) from blood may provide a minimally invasive alternative.

PATIENTS AND METHODS

Hybrid capture-based genomic profiling was carried out on ctDNA from 254 female patients with estrogen receptor-positive breast cancer. Peripheral blood samples were submitted by clinicians in the course of routine clinical care between May 2016 and March 2017. Sequencing of 62 genes was carried out to a median unique coverage depth of 7503×. Genomic alterations (GAs) in ctDNA were evaluated and compared with matched tissue samples and genomic datasets of tissue from breast cancer.

RESULTS

At least 1 GA was reported in 78% of samples. Frequently altered genes were TP53 (38%), ESR1 (31%) and PIK3CA (31%). Temporally matched ctDNA and tissue samples were available for 14 patients; 89% of mutations detected in tissue were also detected in ctDNA. Diverse ESR1 GAs including mutation, rearrangement and amplification, were observed. Multiple concurrent ESR1 GAs were observed in 40% of ESR1-altered cases, suggesting polyclonal origin; ESR1 compound mutations were also observed in two cases. ESR1-altered cases harbored co-occurring GAs in PIK3CA (35%), FGFR1 (16%), ERBB2 (8%), BRCA1/2 (5%), and AKT1 (4%).

CONCLUSIONS

GAs relevant to relapsed/metastatic breast cancer management were identified, including diverse ESR1 GAs. Genomic profiling of ctDNA demonstrated sensitive detection of mutations found in tissue. Detection of amplifications was associated with ctDNA fraction. Genomic profiling of ctDNA may provide a complementary and possibly alternative approach to tissue-based genomic testing for patients with estrogen receptor-positive metastatic breast cancer.

Abstract P4-22-15: Sacituzumab govitecan (IMMU-132), an anti-Trop-2-SN-38 antibody-drug conjugate (ADC) for the treatment of relapsed/refractory, metastatic triple-negative breast cancer (mTNBC): Updated results

Background. mTNBC has an aggressive course with limited effective therapy options and a median progression-free survival (PFS) of 2-4 months (mos) with standard therapy. Sacituzumab govitecan (IMMU-132) is an ADC targeting Trop-2, an antigen present in many epithelial cancers, including TNBC, and delivering SN-38, a topoisomerase I inhibitor as its therapeutic moiety. IMMU-132 was awarded Breakthrough Therapy designation by FDA based on its previously reported activity in relapsed/refractory mTNBC patients. Here we present updated results from the mTNBC cohort of an ongoing phase I/II study (ClinicalTrials.gov, NCT01631552).

Methods. mTNBC patients (pts) received IMMU-132 10 mg/kg on days 1 and 8 every 21 days. Trop-2 expression was not required for enrollment, but available tumor specimens underwent immunohistological (IHC) testing. Efficacy was assessed locally by RECIST 1.1; ORR, PFS and overall survival (OS) were determined for all pts. Pharmacokinetic parameters were estimated in select pts with adequate blood sampling. Immunogenicity to IMMU-132 was examined in all pts.

Results. We previously reported preliminary efficacy results in 51 mTNBC patients. Here we present data on 69 patients with data cutoff June 5, 2016. Median age was 56 years (31-81) and a median of 5 prior therapies (range 1-12), with 66 evaluable for response; ORR was 29% (19/66) 2 confirmed complete (CR) and 17 confirmed partial responses (PR). The median intention-to-treat PFS is 5.6 mos (95% CI, 3.6-7.1 mos) and median OS is 14.3 mos (95% CI, 10.5-18.8 mos). PRs included 2 pts whose tumors did not respond to anti-PD-L1 therapy. The duration of response in the 19 confirmed responders (8 continuing therapy) is 11.5 mos (95% CI = 7.6 to 12.7). The clinical benefit rate (CR+PR+SD>6 mos) for the 66 assessable patients is currently 45.5%. The majority (88%) of archival tumor specimens were moderately (2+) to strongly (3+) positive by IHC for Trop-2, precluding using Trop-2 expression as a selection criterion. Among current adverse events, grade >3 drug-related toxicities included neutropenia (35%), leukopenia (16%), anemia (13%), vomiting (9%), diarrhea (10%), and febrile neutropenia (4%). Clearance kinetics in 8 pts showed IMMU-132 and IgG had a terminal half-life of 15.3 ± 2.7 h and 86.5 ± 40.5 h, respectively, with area under the curve for free SN-38 (unbound) only 3% of the total amount of SN-38 (e.g., IgG bound). Thus, most SN-38 remains bound to the conjugate, and is released at a rate predicted from in vitro serum stability studies. No pt developed anti-IMMU-132 antibodies.

Conclusion The Trop-2-targeting ADC, IMMU-132, delivering cytotoxic doses of SN-38, shows high objective and durable tumor responses with manageable toxicity in heavily-pretreated pts with mTNBC in this updated cohort, supporting further development in this population with an unmet medical need.

Citation Format: Bardia A, Diamond JR, Mayer IA, Isakoff SJ, Abramson V, Starodub AN, O'Shaughnessy J, Kalinsky K, Moroose R, Shah N, Juric D, Shapiro GI, Guarino M, Ocean AJ, Messersmith WA, Berlin JD, Wegener WA, Sharkey RM, Goldenberg DM, Vahdat LT. Sacituzumab govitecan (IMMU-132), an anti-Trop-2-SN-38 antibody-drug conjugate (ADC) for the treatment of relapsed/refractory, metastatic triple-negative breast cancer (mTNBC): Updated results [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 P4-22-15.

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 PD3-06: Safety and efficacy of anti-Trop-2 antibody drug conjugate, sacituzumab govitecan (IMMU-132), in heavily pretreated patients with TNBC

Background: Triple-negative breast cancer (TNBC) comprises about 15% of all breast cancer types, and has a particularly aggressive course. Following first-line therapy, the median PFS is <3 months, and OS is <10 months. Therefore, new treatment strategies are needed. Since Trop-2 is expressed in >90% of TNBC, as measured by IHC, we conducted a trial to evaluate the safety and efficacy of a humanized anti-Trop-2 monoclonal antibody conjugated to a high concentration of SN-38, a camptothecin that is a topoisomerase I inhibitor and the active metabolite of the prodrug irinotecan, with 2-3 logs higher potency than the prodrug.

Methods: After establishing the optimal repeated dose in a Phase I trial (ClinicalTrials.gov, NCT01631552) involving many different solid cancer types, an expanded Phase II was undertaken in a number of cancers, including TNBC. Patients received 8 or 10 mg/kg IMMU-132 i.v. on days 1 and 8 of 21-day repeated cycles. Assessments of safety and response by RECIST1.1 were made weekly and bimonthly, respectively. Tumor biopsies (archival, at baseline prior to treatment, and at disease progression) were obtained when safe and feasible.

Results: As of May 10, 2015, 58 patients with TNBC, with a median of 4 prior therapies (range, 1-11), were treated with IMMU-132. Grade 3-4 toxicities included neutropenia (26%), febrile neutropenia (2%), diarrhea (2%), anemia (4%), and fatigue (4%). No patient developed antibodies to SN-38 or the antibody, and no patient discontinued therapy due to toxicity. Tumor responses were defined as ORR (CR+PR) in 31% of 49 evaluated patients, including 2 with CR, and a clinical benefit ratio (CR+PR+SD>6 mo) of 49% (63% with SD>4 mo; 23 patients continuing treatment after 1st assessment). The current median progression-free survival is 7.3 months with 44% maturity in 50 patients treated at the 8 or 10 mg/kg dose level. Overall survival data are still not mature 20 months after enrollment of first patient. Clinical efficacy correlated to biomarker studies, including Trop-2 expression (target of antibody), topoisomerase-1 expression (target of SN-38), and homologous recombinant deficiency (HRD) assay (marker of DNA repair), is being studied. Immunohistochemistry results in archival specimens currently show 97% positivity of Trop-2 among 34 specimens evaluated, with 79% having high intensity (2+/3+) staining.

Conclusions: The Trop-2-targeting IMMU-132, delivering cytotoxic doses of the topoisomerase I inhibitor, SN-38, shows manageable toxicity, and encouraging anti-tumor activity in relapsed/refractory patients with TNBC. This ADC appears to have a high therapeutic index in heavily pretreated patients.

Citation Format: Bardia A, Diamond JR, Mayer IA, Starodub AN, Moroose RL, Isakoff SJ, Ocean AJ, Guarino MJ, Berlin JD, Messersmith WA, Thomas SS, O'Shaughnessy JA, Kalinsky K, Maurer M, Chang JC, Forero A, Traina T, Gucalp A, Wilhelm F, Wegener WA, Maliakal P, Sharkey RM, Goldenberg DM, Vahdat LT. Safety and efficacy of anti-Trop-2 antibody drug conjugate, sacituzumab govitecan (IMMU-132), in heavily pretreated patients with 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 PD3-06.

Abstract P3-02-02: Targeting the tumor microenvironment: A phase II study of copper-depletion using tetrathiomolybdate (TM) in patients (pts) with breast cancer (BC) at high risk for recurrence

Background: Bone marrow derived VEGFR2+ endothelial progenitor cells (EPCs) and copper-dependent pathways, including lysyl oxidase (LOX), are critical components to remodeling the tumor microenvironment and establishing the pre-metastatic niche. In preclinical models, it has been well established that copper depletion (CD) inhibits tumor progression. We hypothesized that TM-associated CD would reduce EPCs and other copper dependent processes in the pre-metastatic niche in BC pts at high risk for relapse. We investigated the relationship between CD and its effect on EPCs and other components of the tumor microenvironment including LOX, an enzyme critical for cross-linkage of collagen and priming the pre-metastatic niche.

Methods: In this single arm, phase II study, BC pts at high risk for recurrence, defined as node+ triple negative (TN), stage 3 and 4 with no evidence of disease (NED) were enrolled on a trial of CD with TM. Pts received oral TM to maintain ceruloplasmin (Cp) between 5-17 mg/dl for 2 years on the primary study. The primary endpoint was change in EPCs measured by flow cytometry before and during treatment with TM. Secondary endpoints included tolerability, safety and effect of copper depletion on other markers including LOX, quantified by ELISA.

Results: We enrolled 75 pts. The study treatment duration was 24 cycles (each cycle is 28 days). Over 2200 cycles have been administered. The median age is 51 (range 29-66). 45 pts have Stage 2/3 BC and 30 are Stage 4 NED. TNBC pts represent 48%, and 40% of pts are Stage 4 NED. Median Cp level decreased from 28 at baseline to 15.5 (p<0.0001) after one cycle. Copper depletion was most efficient in TNBC, with 91% achieving a target CP within 4 weeks. TM was well tolerated and the only grade 3/4 toxicities were reversible neutropenia (3.2%) and anemia (0.0005%). CD was associated with a significant decrease in EPCs (p=0.0014) and LOX (p<0.001). At a median follow-up of 5.4 years, the PFS for all 75 pts from the start of TM treatment was 71%, including a PFS of 90% for all stage 2/3 pts with TNBC. The overall survival of all patients enrolled in the trial is 86%. Relapse after two years is a rare event. Conclusions: TM is safe, well tolerated and appears to affect multiple copper dependent biologic processes in the tumor microenvironment known to be important for tumor progression. This seems to be most striking in TNBC. We believe, further phase III trials in a high risk for relapse population are warranted.

Citation Format: Nackos E, Willis A, Kornhauser N, Ward M, Andreopoulou E, Cigler T, Moore A, Fitzpatrick V, Cobham M, Schneider S, Wiener A, Guillaume-Abraham J, Warren JD, Rubinchik A, Lane M, Mittal V, Vahdat L. Targeting the tumor microenvironment: A phase II study of copper-depletion using tetrathiomolybdate (TM) in patients (pts) with breast cancer (BC) at high risk for recurrence. [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 P3-02-02.

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.

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 P2-16-23: The ENCHANT-1 trial (NCT01677455): An open label multicenter phase 2 proof of concept study evaluating first line ganetespib monotherapy in women with metastatic HER2 positive or triple negative breast cancer (TNBC)

Background: Hsp90 is a molecular chaperone protein required for the stabilization and activation of many proteins, referred to as Hsp90 ‘clients’, such as HER2, HIF1-a, EGFR, ER, PI3K, AKT, P53 and VEGFR. The drug candidate, ganetespib is a novel triazolone inhibitor of Hsp90, with over 700 patients treated to date. Ganetespib has shown activity in preclinical models of HER2+, ER+/PR+ and TNBC. Early clinical trials documented ganetespib single agent activity in heavily pretreated HER2+ and TNBC patients. Ganetespib has been well tolerated in clinical trials with a favorable safety profile. This efficacy-screening study is designed to provide further evidence of ganetespib activity and identify potentially predictive biomarkers in metastatic breast cancer (BC).

Methods: The ENCHANT-1 Trial is an international, first-line 2-cohort Phase 2 study in BC patients: Cohort A, HER2 amplified (n = 35), and Cohort B, TNBC (n = 35). Patients who present with previously untreated metastatic disease are eligible for treatment with ganetespib at 150 mg/m2 twice weekly on 3 out of 4 wks, for a total of up to 12 wks. Primary endpoint: ORR assessed using RECIST1.1 criteria. Key secondary endpoints include metabolic response as assessed by PET/CT at wk 3 utilizing modified EORTC criteria. Disease progression (PD) at wk 3 by PET imaging indicates discontinuation of study therapy, and is performed to quickly offer patients with metabolic PD a standard of care treatment.

The study is designed as Simon 2-stage requiring at least one OR in 15 patients for the respective cohort to expand to 35 patients. A Steering Committee is established to oversee the overall study and review the interim results.

Results: The study was initiated in 23 centers globally. At the time of submission, a total of 17 patients had been enrolled; TNBC (n = 15) and HER2 (n = 2). Here we report the interim analysis in the TNBC cohort. The median age was 54 years (range 30 -77) with ECOG PS 0 (n = 7/15). Most patients (n = 9) presented with de novo metastatic disease. 5 patients were not evaluable for PET assessment (3 had not yet reached wk 3 and 2 withdrawn before wk 3 for clinical progression), and 9 patients were not evaluable for objective response at wk 6 (3 withdrawn before or at wk 3 for clinical progression and 6 had not yet reached wk 6 evaluation). In the 10 patients with evaluable PET imaging, 9 patients achieved metabolic (m) response (2 mPR, 4 mSD with dominant tumor shrinkage and 3 SD) and one patient with mPD. In the 6 patients evaluable for OR at wk 6, one patient achieved PR, 2 SD and 3 PD. Treatment with ganetespib was well tolerated; the most common AEs were mild or moderate diarrhea (8/15, 53%), fatigue (5/15, 33%), decreased appetite (4/15, 27%), insomnia (4/15, 27%), and nausea (4/15, 27%).

Conclusion: Ganetespib single agent was generally well tolerated and showed anti-tumor activity TNBC patients as early as 3 weeks following treatment. PET seems to be a good tool to screen antitumor activity of new agents in early settings rather that in heavily pretreated patients. The TNBC cohort has met the protocol criteria for proceeding to stage 2.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-23.

Abstract P6-05-06: Association of HER2/neu single nucleotide polymorphism with trastuzumab-related cardiotoxicity

Background: Treatment with trastuzumab prolongs overall survival when given to patients (pts) with Her2/neu+ breast cancer (BC). The primary toxicity of trastuzumab is cardiotoxicity and the incidence is estimated at 2-4% in the adjuvant setting. The mechanism for trastuzumab-induced cardiotoxicity is not known. Although Her2neu expression is usually not seen on cardiac myocytes, its expression has been shown to be upregulated after chemotherapy. Trastuzumab is a monoclonal antibody that binds to the extracellular domain of Her2/neu. We hypothesized that single nucleotide polymorphisms (SNPs) in the Her2/neu receptor may play a role in trastuzumab associated cardiotoxicity.

Methods: 140 pts with BC who were treated with chemotherapy and trastuzumab were enrolled into an IRB approved protocol at the Weill Cornell Medical College between July 2008 and March 2013. Cardiotoxicity was defined as either symptomatic CHF, or a decline in LVEF of 15% (or if LVEF <55% a decline in LVEF of 10%) that required management with medications and led to temporary or permanent discontinuation of trastuzumab. 11 nonsynonomous human ErbB2 SNPs were identified in the National Center for Biotechnology Information SNP database (rs1136201, rs2172826, rs28933368, rs28933369, rs28933370, rs34602395, rs36085723, rs4252633, rs55943169, rs56366519, rs61552325). Genotyping of SNPs was performed on DNA prepared from blood or buccal washes. The relationship between SNP characteristics and cardiotoxicity status was assessed by the chi-square test and multivariable logistic regression analysis.

Results: 140 subjects (29 with cardiotoxicity and 111 without) had 11 SNPs sequenced. Median age of subjects was 56 years (range: 32-85), mean baseline LVEF was 65% (±6%). 16.4% of subjects had hypertension (HTN). 80% of patients were Caucasian, 10% East Asian, 7.1% African American, 2.9% South Asian. There were two SNPs for which there was variation seen among subjects: rs 1136201 (corresponding to codon 655) and rs61552325 (codon 1170). The frequencies of the codon 655 polymorphisms were: AA (Ile/Ile) 67.9%, AG (Ile/Val) 29.3%, and GG (Val/Val) 2.9%. The frequencies of the codon 1170 polymorphisms were: CC (Pro/Pro) 20.7%, GC (Ala/Pro) 45.7%, and GG (Ala/Ala) 33.6%. There was no association observed between the codon 655 polymorphism and cardiotoxicity (p = 0.96). A significant association between cardiotoxicity and the codon 1170 polymorphism was observed, with subjects having cardiotoxicity being more likely to carry the CC allele compared with subjects without cardiotoxicity (34.5% vs 17.1%, p = 0.04). This association persisted after multivariable adjustment for age, race, and HTN status (adjusted OR = 2.60, 95% CI = 1.02-6.62, p = 0.046).

Conclusion: In this study, the Her2/neu 1170 Pro/Pro polymorphism was associated with trastuzumab cardiotoxicity. If confirmed in a larger series, this polymorphism could be used to identify pts who may be at increased risk for cardiotoxicity and who may benefit from treatments associated with less cardiotoxicity. Furthermore, the Her2/neu 1170 SNP has previously been implicated as a minor histocompatibility antigen, and our findings raise the possibility that immune mediated mechanisms may play a role in trastuzumab related cardiotoxicity.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-05-06.

Abstract P3-13-05: Eribulin mesylate as first-line therapy for locally recurrent or metastatic HER2-negative breast cancer: Results of a phase 2, multicenter, single-arm study

Background: Eribulin mesylate is a novel nontaxane microtubule dynamics inhibitor that is approved for treatment of metastatic breast cancer (MBC) in patients who have previously received at least two chemotherapeutic regimens for MBC. We present final data from a phase 2 study that evaluated the efficacy and safety of eribulin as first-line therapy for HER2-negative (HER2-) MBC.

Methods: Patients with measureable HER2- locally recurrent or MBC with ≥12 months since prior neoadjuvant or adjuvant chemotherapy received eribulin mesylate 1.4 mg/m2 IV on days 1 and 8 of each 3-week cycle. Endpoints included objective response rate (ORR) (primary), safety, progression-free survival (PFS), time to response (TTR), and duration of response (DOR). Tumor assessments were conducted every 6 weeks for the first 6 cycles and every 6-12 weeks thereafter per RECIST 1.1.

Results: Fifty-six patients enrolled and received eribulin. Patients had a median age of 56 years (range 31-85); 32 (57%) had an ECOG status of 0; 17 (30%) had de novo stage IV; 33 (59%) had prior (neo)adjuvant therapy, including anthracycline and/or taxane (A/T) chemotherapy. Thirty-nine patients (70%) had visceral disease (45% liver, 32% lung); 41(73%) had estrogen receptor-positive (ER+) disease and 12 (21%) had triple negative (TN) disease. Thirty-two patients (57%) completed at least 6 cycles of treatment; among the 24 patients who completed fewer than 6 cycles, reasons for not completing were progressive disease (PD; n = 18), adverse events (AEs; n = 3) and patient choice (n = 3). The median number of cycles delivered was 7 (range 1-39); 6 patients (11%) received treatment for ≥12 months. Overall ORR was 27%, with median TTR of 1.4 months and median DOR of 7.4 months; stable disease (SD) rate was 48% (Table 1). Median PFS was 6.8 months. Thirty-five patients (63%) had grade 3/4 treatment-related AEs (Table 2). Treatment-related serious AEs occurred in 5 (9%) patients: neutropenia (5%), febrile neutropenia (5%), and leukopenia (2%).

Conclusions: The results of this study suggest that first-line eribulin has antitumor activity in ER+/HER2- and TN MBC with safety consistent with the known profile. Further exploration of this treatment as part of earlier lines of breast cancer therapy, including neo/adjuvant, is warranted.

Table 1. Summary of EfficacyEfficacyEribulin-treated patients N = 56ORR, n (%)15 (27)CR0PR15 (27)SD27 (48)PD12 (21)Clinical benefit rate (ORR + ≥6 mo SD)27 (48)Median months (95% CI) TTR1.4 (1.2, 2.7)DOR7.4 (4.7, NE)PFS6.8 (4.4, 7.4)NE, not estimable

Table 2. Treatment-Related AEsAE (N = 56)All events (%)Grade 3/4 (%)Leading to study drug withdrawal1111Leading to dose reduction3427Common AEs (≥25%)  Alopecia820Neutropenia7050Fatigue572Peripheral neuropathy5420Nausea460Anemia364Leukopenia3018Constipation270

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-13-05.

Abstract P2-16-05: Efficacy of ABT-888 (veliparib) in patients with BRCA-associated breast cancer

Background: The potential for exploiting BRCA deficiencies with DNA repair inhibitors has both pre-clinical and clinical support. ABT-888 (veliparib), a DNA repair inhibitor initially thought to target Poly(ADP-Ribose) Polymerases (PARP), has demonstrated in vitro inhibition of BRCA1 and BRCA2 deficient mouse embryonic stell cells, with a larger effect on BRCA1 cells. We report on the pre-planned interim analysis of the efficacy of single agent veliparib in patients with either BRCA1 or BRCA2-associated stage IV breast cancer. Methods: BRCA 1 or 2 carrier patients with stage IV breast cancer, with measurable disease, without prior exposure to a PARP inhibitor or a platinum compound in the metastatic setting, were eligible. Velapirib was administered orally, at doses of 400 mg twice daily. Dose adjustments based on toxicity were permitted. Patients progressing on velapirib alone received carboplatin at an AUC of 5, IV, given Q 21 days, and velapirib 150 mg twice daily (the maximum tolerated dose [MTD] of the combination from our completed Phase I study: J Clin Oncol 30, 2012 [suppl; abstr 1024]). Patients were to be accrued from 7 NCI NO1- supported consortia. Initially 10 patients were to be accrued to each stratum (BRCA1 and BRCA2) to provide evidence of single agent activity. If there was sufficient activity to warrant consideration of velapirib as single agent therapy (defined as 2 or more confirmed partial [PR] or better responses out of 10 per stratum), an additional 12 patients would be accrued per stratum. Results: 20 evaluable patients (11 BRCA1 and 9 BRCA2 [1 in screening]) have been accrued, the majority with lung or liver as visceral metastatic sites of disease. Median age (range) is 46 (29-68) years. Tumors from 9 patients were hormone receptor positive. BRCA1 cohort: 4 of 11 patients are off treatment at a median of 2 months (1-4); 1 patient stopped velapirib due to toxicity (grade 2 rash/pruritus, grade 2 vomiting), 3 stopped for progressive disease (one with an unconfirmed PR). Seven patients are still on single agent veliparib with 1 unconfirmed PR, and 1 patient with two evaluations showing stable disease. BRCA2 cohort: 2 patients are off treatment at 2 months for progressive disease, 7 are still on treatment with 1 confirmed PR, and 3 unconfirmed PRs. Data on patients receiving combination of velapirib and carboplatin after progression is too early. Treatment-related toxicity is being updated and has so far been reported from 14 patients: 1 patient had grade 3 fatigue, 1 patient with liver metastasis had both grade 3 alanine aminotransferase elevation and grade 3 abdominal pain. Grade 2 toxicities occurring in more than 1 patient included nausea/vomiting (6 patients), chills (2 patients), and fatigue (2 patients). Conclusion: Velapirib has single agent activity in both BRCA1 and BRCA2-associated stage IV breast cancer patients, and is well-tolerated. Mature response, treatment, and toxicity data will be presented.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-05.

Abstract P4-12-12: Phase 2, multicenter, single-arm study of eribulin mesylate + trastuzumab as first-line therapy for locally recurrent or metastatic HER2-positive breast cancer

Background: Eribulin mesylate, a non-taxane microtubule dynamics inhibitor, has been approved for patients with metastatic breast cancer (MBC) who have previously received ≥2 chemotherapeutic regimens for MBC. We present final data from a phase 2 study that evaluated efficacy and safety of eribulin + trastuzumab as first-line therapy for locally recurrent or metastatic human epidermal growth factor receptor 2 positive (HER2+) BC.

Methods: Patients received eribulin mesylate at 1.4 mg/m2 IV on days 1 and 8 of each 21-day cycle and an initial trastuzumab dose of 8 mg/kg IV on day 1, followed by 6 mg/kg on day 1 of each subsequent cycle. Endpoints include objective response rate (ORR), safety, progression-free survival (PFS), time to response (TTR), and duration of response (DOR). Tumor assessments were conducted every 6 weeks for the first 6 cycles and every 6-12 weeks thereafter per RECIST 1.1.

Results: Fifty-two patients with a median age of 60 years (range 31- 81) were treated; 96% had stage IV disease, 73% had visceral disease, and 48% had liver metastases. Thirty one patients had prior neo/adjuvant chemotherapy (11 had prior anthracycline, and 22 had prior taxane). Patients received a median of 10(0, 33) cycles of eribulin and 11(1, 31) cycles of trastuzumab. ORR was 67% with median TTR of 1.3 months and PFS of 11.5 months (Table). The most common (>5%) Grade 3/4 treatment related treatment emergent (TRTE) AEs were neutropenia (n = 20; 38.5%), peripheral neuropathy (n = 14; 26.9%) and febrile neutropenia (n = 4; 7.7%). Serious TRTE AEs occurred in 14 patients and included neutropenia (n = 9; 17.3%), febrile neutropenia (n = 4; 7.7%), and peripheral neuropathy (n = 3; 5.8%). Reasons for discontinuation were AEs (n = 7) and PD (n = 22).

Table. Summary of Efficacy EndpointsEfficacy EndpointsEribulin/Trastuzumab N = 52Objective Response Rate, n (%)35 (67)- Complete Response (CR)2 (4)- Partial Response (PR)33 (64)Stable Disease (SD)15 (29)Progressive Disease (PD)1 (2)Not Evaluable1 (2)Overall Clinical Benefit Rate, n (%)42 (81)Time to First Objective Response, median months (95% CI)1.3 (1.2, 1.4)Duration of Objective Response, median months (95% CI)a11.1 (6.5, 17.8)Progression-Free Survival, median months (95% CI)11.5 (7.3, 13.5)Duration of Stable Disease, median months (95% CI)7.1 (5.2, 13.5)Clinical Benefit Rate = ORR+ ≥6 mo SD; an = 35

Conclusions: This study suggests that the combination of eribulin + trastuzumab first-line therapy for locally recurrent or metastatic HER2+ BC has an acceptable safety profile and results in considerable tumor response with a long DOR. Additional larger studies with this combination are warranted.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-12.

Tetrathiomolybdate-associated copper depletion decreases circulating endothelial progenitor cells in women with breast cancer at high risk of relapse

BACKGROUND

Bone marrow-derived endothelial progenitor cells (EPCs) are critical for metastatic progression. This study explores the effect of tetrathiomolybdate (TM), an anti-angiogenic copper chelator, on EPCs in patients at high risk for breast cancer recurrence.

PATIENTS AND METHODS

This phase 2 study enrolled breast cancer patients with stage 3 and stage 4 without evidence of disease (NED), and stage 2 if triple-negative. TM 100 mg orally was administered to maintain ceruloplasmin <17 mg/dl for 2 years or until relapse. The primary end point was change in EPCs.

RESULTS

Forty patients (28 stage 2/3, 12 stage 4 NED) were enrolled. Seventy-five percent patients achieved the copper depletion target by 1 month. Ninety-one percent of triple-negative patients copper-depleted compared with 41% luminal subtypes. In copper-depleted patients only, there was a significant reduction in EPCs/ml by 27 (P = 0.04). Six patients relapsed while on study, of which only one patient had EPCs maintained below baseline. The 10-month relapse-free survival was 85.0% (95% CI 74.6%-96.8%). Only grade 3/4 toxicity was hematologic: neutropenia (3.1% of cycles), febrile neutropenia (0.2%), and anemia (0.2%).

CONCLUSIONS

TM is safe and appears to maintain EPCs below baseline in copper-depleted patients. TM may promote tumor dormancy and ultimately prevent relapse.

Abstract P1-15-07: Ixabepilone-associated peripheral neuropathy in metastatic breast cancer patients and its effects on the ultrastructure of neurons

Background: Peripheral neuropathy is a dose-limiting toxicity of most microtubule-stabilizing chemotherapeutic agents. Ixabepilone, a semisynthetic analog of the natural epothilone B, has activity in a wide range of tumors including taxane-resistant disease. In this study, we sought to understand the effect of ixabepilone on the development of peripheral neuropathy both clinically and its effect at the ultrastructural level of the peripheral nerves and circulating factors over time. Parallel studies in animal models of neuropathy were performed at the same time (Proc AACR 2010 Abstract 4184).

Methods: This open-label, non-randomized phase II study enrolled 14 patients with metastatic breast cancer. Ixabepilone was administered by 2 schedules: the FDA approved dose of 40 mg/m2 every 3 weeks (q3w) and 16 mg/m2 on day 1, 8, and 15 of a 28-day cycle (weekly). Five controls, 2 with residual taxane-associated peripheral neuropathy and 3 with no prior chemotherapy or peripheral neuropathy, were also accrued. The primary objectives were to characterize the natural history of ixabepilone-associated peripheral neuropathy using the Total Neuropathy Score Clinical (TNSc) assessment tool prior to each cycle and to correlate changes in the ultrastructure of dermal myelinated nerve fibers via a 3 mm punch biopsy of an area 10 cm above the lateral malleolus every 2 cycles with electron microscopy (EM), as well as circulating factors (both inflammatory and neurotrophic) considered to be important in the pathogenesis of chemotherapy-induced peripheral neuropathy. Secondary objectives included progression-free survival (PFS) and non-neurologic toxicity.

Results: 14 patients were enrolled and were equally divided between the 2 schedules of ixabepilone chemotherapy. There were no differences in baseline characteristics between the two groups. Mean age was 54 years (range 32–71). Mean number of previous chemotherapy regimens was 3.5 (range 0–8). 57% of patients had received a taxane in the adjuvant setting and 64% in the metastatic setting. The mean neuropathy score (TNSc) at baseline was 4.6 (range 1–11). At a mean cumulative dose of 185 mg/m2, the TNSc with ixabepilone q3w schedule was 3.7 points higher/worse (95% CI: 2.2–5.3, p = 0.03) than the mean score observed in patients on the weekly schedule. The sensory component was most significantly affected, predominantly numbness. In 3 patients, the chemotherapy schedule was changed from every 3 weeks to weekly due to &gt; grade 2 toxicity at a mean cumulative dose of 107 mg/m2, and TNSc decreased/improved by 2.7 points. PFS in patients on q3w ixabepilone was 133 days (range 28–280) and in patients on weekly ixabepilone was 179 days (range 66–336), nonsignificant. Evaluation of EM and circulating factors is ongoing.

Conclusions: Weekly ixabepilone appears to have a more favorable neurotoxicity profile compared to the standard q3w schedule. Integration of the EM data and the circulating factor data are underway and will be presented. Ixabepilone-associated peripheral neuropathy may improve in patients switched to weekly ixabepilone without compromising efficacy.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-15-07.

Abstract P1-12-02: Results of a phase 2, multicenter, single-arm study of eribulin mesylate as first-line therapy for locally recurrent or metastatic HER2-negative breast cancer

Background: Eribulin mesylate is a novel nontaxane microtubule dynamics inhibitor that is approved in patients (pts) with metastatic breast cancer (MBC) who have previously received at least two chemotherapeutic regimens for MBC. We are reporting a preliminary planned analysis (first 6 cycles of treatment) of a phase 2 study that evaluates efficacy and safety of eribulin as first-line therapy for HER2-negative MBC.

Methods: Pts with measureable HER2-negative locally recurrent or MBC with at least 12 months since prior neoadjuvant or adjuvant chemotherapy received eribulin mesylate at 1.4 mg/m2 IV on days 1 and 8 of each 3-week cycle. Endpoints include objective response rate (ORR) (primary), safety, progression free survival (PFS), time to response (TTR), and duration of response (DOR). Tumor assessments were evaluated every 6 weeks for the first 6 cycles and every 6–12 weeks thereafter per RECIST 1.1.

Results: 54 of 56 enrolled pts had at least 1 post-baseline assessment. The median number of cycles delivered was 7 (range 1,21). Pt characteristics: median age, 56 yrs (range 31–85); ECOG of 0, 32 (57%); 29% had de novo stage IV; 38/56 (68%) had prior neo/adjuvant (45% had anthracycline and 45% taxane, the majority of which were given together). Seventy percent have visceral disease (45% liver, 38% lung); 41 (73%) have estrogen receptor-positive (ER) disease and 12 (21%) have triple negative (TN) (ER−/PR−/HER2−) disease. Objective response data are found in Table 1.

Abstract P5-20-04: Eribulin mesylate + trastuzumab as first-line therapy for locally recurrent or metastatic HER2-positive breast cancer: results from a phase 2, multicenter, single-arm study

Background: Eribulin mesylate, a novel non-taxane microtubule dynamics inhibitor, has been approved for patients with metastatic breast cancer (MBC) who have previously received at least two chemotherapeutic regimens for MBC. This study evaluates efficacy and safety of eribulin + trastuzumab (TRAZ) as first-line therapy for human epidermal growth factor receptor 2 positive (HER2+) locally recurrent or MBC.

Methods: Patients received eribulin mesylate at 1.4 mg/m2 IV on days 1, 8 and TRAZ initial dose of 8 mg/kg IV on day 1 every 21 days, followed by 6 mg/kg on day 1 of each subsequent cycle. For study inclusion, patients could have been previously treated with TRAZ, but at least 12 months should have passed since any prior neoadjuvant or adjuvant chemotherapy was used. Endpoints include objective response rate (ORR) (primary), safety, progression free survival (PFS), time to response (TTR), and duration of response (DOR). Tumor assessments are evaluated every 6 weeks for the first 6 cycles and every 6–12 weeks thereafter per RECIST 1.1.

Results: Updated results presented here as of June 1, 2012; 37 of 52 planned patients have been treated. Patient characteristics are as follows: median age: 58 years (range, 31–81), 70% have luminal subtype, 95% are stage IV disease, and 73% have visceral disease, 46% had prior neo/adjuvant, 22% had prior anthracycline and 32% had prior taxane, 35% had original diagnosis of MBC. Patients received median of 7 (1,20) cycles for eribulin and 9 (1,23) cycles for TRAZ. The most common treatment related AEs are reported in Table 1.

Abstract P6-11-04: Targeting the tumor microenvironment: tetrathiomolybdate decreases circulating endothelial progenitor cells in women with breast cancer at high risk of relapse

Background: Bone marrow-derived endothelial progenitor cells (EPCs) constitute an important part of the tumor microenvironment and are critical for metastatic progression in preclinical models and breast cancer patients (Jain et al, Breast Cancer Res Treat, 2012). Tetrathiomolybdate (TM), a copper-depleting compound inhibits angiogenesis, tumor growth, and metastasis. This study explores the effect of TM on EPCs in patients at high risk for breast cancer recurrence.

Methods: This phase II study enrolled stage 3, 4 without evidence of disease (NED), and any node-positive triple negative breast cancer patient. Only concomitant hormone therapy was allowed. Patients received induction TM 180 mg daily at baseline followed by an equal or lower daily dose (median 100 mg, range 0–140) to maintain ceruloplasmin (Cp) level &lt; 17 mg/dl (target for copper depletion). We monitored EPCs (CD45dim/CD133+/VEGFR2+), Cp, CEA, and CA15-3 at baseline and monthly. Wilcoxon signed-rank was used to compare Cp and EPC levels between baseline and subsequent time points. All p-values were two-sided with statistical significance evaluated at the 0.05 alpha level.

Results: 50 patients (33 adjuvant, 17 Stage 4 NED, and 22 triple negative) were enrolled. In the first 40 patients enrolled who had received at least 24 months of TM, EPC and Cp data were available for analysis. Of these 40 patients, 1 patient did not take TM due to patient preference, and 736 cycles of TM (average 18.9 per patient) were administered. Median age was 50 years (range 29–66). Median number of tumor size and positive lymph nodes among adjuvant patients were 3.5 cm (range 1.2–7) and 9 (range 0–42), respectively. Of the patients receiving hormone therapy, 11 patients were on tamoxifen and 16 patients were on an aromatase inhibitor. Median baseline Cp level was 30 mg/dL (range 20–47). 71% patients adequately copper depleted at month 1 to a mean Cp of 14.8 mg/dL. A larger proportion of triple negative patients copper depleted (82%) compared to hormone receptor positive subtypes (47%) and HER2/neu positive subtypes (67%). Median EPCs/ml decreased from baseline to last dose by 16 in patients that achieved the copper depletion target, p = 0.014. Conversely, in patients that did not copper deplete, median EPCs/ml increased by 136, p = 0.005. Of the 50 patients on study, 7 patients relapsed in which a significant increase in EPCs preceded an objective clinical relapse and a tumor marker rise by a median of 1 month. Only grade 3/4 toxicity was hematologic, occurred in 49 cycles (6.7%), and resolved in 5–13 days with TM held and resumed at a lower dose.

Conclusions: TM is a well-tolerated oral copper chelator that may contribute to maintaining EPCs below baseline in copper-depleted patients. Molecular subtype may impact on the ability to copper deplete. EPCs may have potential as a surrogate marker for early relapse and as a therapeutic target for interrupting the metastatic progression.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-11-04.

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 &gt;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 &gt;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.

Employment after a breast cancer diagnosis: a qualitative study of ethnically diverse urban women

Employment status is related to treatment recovery and quality of life in breast cancer survivors, yet little is known about return to work in immigrant and minority survivors. We conducted an exploratory qualitative study using ethnically cohesive focus groups of urban breast cancer survivors who were African-American, African-Caribbean, Chinese, Filipina, Latina, or non-Latina white. We audio- and video-recorded, transcribed, and thematically coded the focus group discussions and we analyzed the coded transcripts within and across ethnic groups. Seven major themes emerged related to the participants' work experiences after diagnosis: normalcy, acceptance, identity, appearance, privacy, lack of flexibility at work, and employer support. Maintaining a sense of normalcy was cited as a benefit of working by survivors in each group. Acceptance of the cancer diagnosis was most common in the Chinese group and in participants who had a family history of breast cancer; those who described this attitude were likely to continue working throughout the treatment period. Appearance was important among all but the Chinese group and was related to privacy, which many thought was necessary to derive the benefit of normalcy at work. Employer support included schedule flexibility, medical confidentiality, and help maintaining a normal work environment, which was particularly important to our study sample. Overall, we found few differences between the different ethnic groups in our study. These results have important implications for the provision of support services to and clinical management of employed women with breast cancer, as well as for further large-scale research in disparities and employment outcomes.

OT3-01-17: Randomized, Double-Blind, Placebo-Controlled Phase II Trial of Low-Dose Metronomic Cyclophosphamide Alone or in Combination with Veliparib (ABT-888) in Chemotherapy-Resistant ER and/or PR-Positive, HER2/neu-Negative Metastatic Breast Cancer: New York Cancer Consortium Trial P8853

Background: Veliparib is an orally available, small molecule inhibitor of poly(ADP-ribose) polymerase (PARP). PARP is an essential nuclear enzyme that plays a role in recognition of DNA damage and facilitation of DNA repair. PARP inhibitors potentiate the cytotoxicity of DNA-damaging agents, including cyclophosphamide (C). The rationale for the proposed trial is as follows: (1) low-dose, continuous metronomic C (50 mp PO daily) has activity in refractory metastatic breast cancer (MBC), (2) PARP is induced by DNA damaging agents, (3) PARP expression is comparable in ER-positive and ER-negative disease, (4) some ER-positive breast cancers exhibit defective homologous recombination pathway repair genes (eg, RAD51 and XRCC3), (5) the PARP inhibitor iniparib appears to be more effective when used in chemotherapy resistant disease. Taken together, these findings suggest that veliparib-C combination may be more effective than metronomic C alone in chemotherapy resistant MBC. Trial design: A randomized Phase II trial design 1:1. S. Blocked randomization will be performed at all participating sites. Patients are randomized to oral C (50mg PO daily) plus either veliparib (60mg PO daily) or matching placebo.

Eligibility criteria:(1) ER- and or PR-positive, HER2−negative MBC, (2) ECOG PS 0–1, (3) at least 2 prior chemotherapy regimens for MBC, including a taxane and capecitabine. 4) at least 1 line of endocrine therapy for metastatic disease (includes relapse while receiving endocrine therapy).

Specific aims: Primary: To determine if the addition of veliparib to metronomic dose C improves median progression free survival (PFS) compared with C alone in patients with ER and/or PR-positive, Her2-negative MBC who progressed on at least two lines of prior chemotherapy and one line of prior endocrine therapy.

Secondary: 1)To determine if the addition veliparib to C chemotherapy improves a) response rate b) clinical benefit rate (defined as objective response plus stable disease for at least 24 weeks from day +1) 2) Survival in patients treated with C alone and C plus veliparib. 3) Adverse event profile in patients treated with C alone and C plus veliparib.

Translational: Exploratory analyses will evaluate whether the macroH2A1.1 and PARP1 expression status in archival paraffin, or veliparib-induced PAR downregulation in peripheral blood mononuclear cells, is predictive of benefit from veliparib.

Statistical methods: The primary endpoint is PFS, and the trial is powered to detect an increase in median PFS from 3 to 6 months (alpha=0.10, beta=0.10), which will require enrollment of 62 eligible patients over 12 months.

Enrollment: The study is active and open to enrollment.

Clinical trials.gov NCT01351909

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT3-01-17.

P1-03-02: The Norton-Simon Hypothesis and Cancer Stem Cells: How Cancer Stem Cells May Explain the Effectiveness of Dose-Dense Chemotherapy

Background: Systemic therapies are effective initially in controlling and reversing tumor growth; however, residual cancers will invariably re-grow despite this initial response. We have published data from paired human breast cancer samples that standard therapy every three weeks kills dividing daughter cells but not tumor-initiating cells (TICs), so that samples obtained after therapy are enriched for CD44+/CD24−/low putative “tumor-initiating” or “cancer stem” cells, indicating that standard treatment regimens are missing the critical targets, TICs. Interestingly, we have recent data in human breast tumors that indicate that TICs may in fact be chemosensitive initially, with a decrease in TICs observed within two days of chemotherapy, but shortly thereafter, TICS are actually induced by chemotherapy.

Materials and Methods: To evaluate TICs response to chemotherapy, mice with human breast tumor xenograft lines BCM-2665a and BCM-2147 were treated with vehicle, 10-, or 33-mg/kg docetaxel, and then tumors were collected for TIC assays and molecular analysis at both 48 and 72h after treatment. Using Affymetrix gene expression microarrays and reverse phase protein array (RPPA) analysis with 119 different validated antibodies, we identified pathways involved in regulation of TICs. Results: According to flow cytometric analysis for TIC markers and mammosphere (MS) formation efficiency, BCM-2665 TICs were reduced by docetaxel treatment compared to vehicle-treated at 48h post 10 mg/kg docetaxel (4-fold decrease) and 48 and 72h post 33 mg/kg docetaxel compared to control (14- and 2-fold decrease, respectively). Although the BCM-2147 TICs did not significantly decrease at any time points or doses tested, they were clearly induced at 72h post-treatment compared to control. Additionally, BCM-2665 TICs were increased within 72h post 10 mg/kg docetaxel, indicating that these time points are ideal for defining the mechanisms responsible for induction of TICs. Ingenuity Pathway Analysis of Affymetrix microarray data for both BCM-2665 and BCM-2147 revealed induction of inflammatory pathways, suggesting leukocyte infiltration associated with induction of TICs. Furthermore, RPPA analysis confirmed gene expression changes from the microarray data, and implicated apoptosis and inflammatory pathways. Sixteen of 28 proteins significantly changed with activation of CSC are involved in development of leukocytes. Discussion: These findings are consistent with the Norton-Simon Hypothesis in that chemotherapy regimens given more frequently may in fact eliminate TICs, thereby explaining the proven increased effectiveness of dose-dense chemotherapy. Based on when TICs became chemoresistant, we are comparing dose-dense treatment (4 mg/kg docetaxel every 3 days) to a traditional single dose of 32 mg/kg, in an effort to eliminate the tumor cells that cause tumor recurrence. Furthermore, our analysis of gene expression at both the RNA and protein level implicated the immune cells as TICs inducers. Since our immunocompromised mice lack T- and B- cells but have active macrophages, macrophages are indicated as inducers of TICs. We are focusing our current efforts at identifying how immune cells activate TICs and thus enhance tumorigenesis.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-03-02.

Abstract P3-15-06: No Correlation between Endocrine Symptoms and Musculoskeletal Symptoms in Women Receiving Adjuvant Aromatase Inhibitor Therapy

Background:

The etiology of Aromatase Inhibitor (AI) associated musculoskeletal symptoms remains unclear. It has been proposed that musculoskeletal side effects are related to the estrogen depletion achieved on AI therapy. Estrogen depletion with AI therapy is known to result in endocrine side effects. The 18-item Functional Assessment of Cancer Therapy Breast Cancer-Endocrine Subscale (FACTB-ES) is a reliable and well validated quality of life questionnaire shown to be sensitive to changes in endocrine symptoms in breast cancer patients. The objective of this study was to determine whether among women with breast cancer treated with adjuvant AI therapy, self reported musculoskeletal side effects correlate with increased hormonal side effects as measured by the FACTB-ES. Methods:

In this 6 month, single center, prospective cohort study, post-menopausal women with hormone-sensitive, non-metastatic breast cancer prescribed AIs by their treating oncologist were evaluated by a rheumatologist at baseline (before starting the AI) and at 6 months. Women who reported new or worsening musculoskeletal symptoms since starting the AI were classified as symptomatic. The FACTB-ES was administered at each visit.

Changes in scores between baseline and 6 months were compared between

the symptomatic and asymptomatic groups

Results:

Thirty-five subjects completed the 6 month follow up period. Nineteen (54%) were symptomatic and n=2 (5.7%) discontinued the AI due to these musculoskeletal symptoms. Mean time to onset of symptoms was 6 weeks (range 2 to 18 weeks). Baseline characteristics including age, ethnicity and body mass index did not differ between the groups. There was no significant difference in hormonal symptoms between groups. Both groups had equivalent worsening of their endocrine symptoms as seen by the reduction in their FACTB-score. The mean change in FACTB-ES score was -2.52 (range: -31.00, 23.00) in the symptomatic women versus -2.06 (range: -19.00, 22.21) in the asymptomatic women (Wilcoxon rank sum p=0.95). Conclusions:

These data suggest that endocrine symptoms as measured by the FACTB-ES do not correlate with the development of musculoskeletal pain in women treated with adjuvant AI therapy for breast cancer. Though larger studies are necessary to confirm these results, the musculoskeletal symptoms associated with AI use may not be estrogen-dependent.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-15-06.

Treatment of metastatic breast cancer: second line and beyond

Increasing use of standard chemotherapy, especially anthracycline- and taxane-based therapies, in early-stage breast cancer has led to a corresponding increase in heavily pretreated and/or treatment-resistant cases of metastatic breast cancer (MBC). Thus, second and later lines of MBC therapy frequently involve the clinically challenging picture of progressive disease and limited treatment options. While several prognostic factors have been identified to aid treatment selection in MBC patients, treatment is palliative and aimed at prolonging survival, controlling symptoms, and maximizing patients' quality of life. No globally accepted standard exists for meeting these goals, and treatment patterns vary according to region. The list of available agents for the treatment of MBC is increasing with newer chemotherapeutic agents and molecular-targeted therapies. Within recent years, several single-agent and combination chemotherapy regimens have been shown to improve progression-free survival and reduce symptoms of disease in clinical studies in patients with resistant and/or heavily pretreated MBC. However, at present, the demonstrated benefits of these medical interventions have usually not included extension of overall survival times. It is hoped that in the near future, ongoing refinements to treatment approaches used in second-line settings and beyond will allow meaningful improvements in symptom control and survival in MBC.

Phase I trial of ixabepilone plus pegylated liposomal doxorubicin in patients with adenocarcinoma of breast or ovary

BACKGROUND

Ixabepilone is a semisynthetic epothilone B analogue that is active in taxane-resistant cell lines and has shown activity in patients with refractory breast and ovarian cancer. We carried out a phase I trial of ixabepilone plus pegylated liposomal doxorubicin (PLD) in patients with advanced taxane-pretreated ovarian and breast cancer.

METHODS

Patients with recurrent ovarian or breast carcinoma received PLD every 3 or 4 weeks plus five different dose schemas of ixabepilone in cohorts of three to six patients.

RESULTS

Thirty patients received a total of 142 treatment cycles of the PLD-ixabepilone combination. The recommended phase II dose and schedule of ixabepilone was 16 mg/m(2) on days 1, 8, and 15 plus PLD 30 mg/m(2) given on day 1, repeated every 4 weeks. Hand-foot syndrome and mucositis were dose limiting when both ixabepilone and PLD were given every 3 or 4 weeks. Objective responses were observed in 3 of 13 patients (23%) with breast cancer and 5 of 17 patients (29%) with ovarian cancer.

CONCLUSION

Ixabepilone may be safely combined with PLD, but tolerability is highly dependent upon the scheduling of both agents. This combination demonstrated efficacy in patients with breast and ovarian cancer and merits further evaluation in these settings.

A Phase II Trial Tetrathiomolybdate (TM), a Copper Depleting Compound, and Its Effect on Circulating Endothelial Progenitor Cells (EPCs) in Patients with Breast Cancer (BC) at High Risk of Recurrence

Background: EPCs are critical to tumor angiogenesis, are increased in BC patients (pts) and are probably an early marker for paclitaxel response. Copper is required for angiogenesis, and pre-clinical data suggest that TM, a copper-depleting compound, inhibits angiogenesis and maintains tumor dormancy. We sought to measure the effect of TM on circulating endothelial progenitor cells (EPCs) in pts at high risk of BC recurrence and to evaluate the effect of copper depletion on EPCs. Methods: This analysis is part of an ongoing phase II study of TM in BC pts at high risk of recurrence defined as any node positive triple negative (TN) BC, Stage III or IV with no evidence of disease (NED). All therapy other than hormonal was completed at least 6 weeks prior to study. Treatment: TM 180 mg daily to achieve a target ceruloplasmin (Cp) level of 5-15 mg/dL (copper depletion), and then 100 mg daily. We monitored levels of EPCs (CD45dim, CD133+, VEGFR2+), CEA, CA15-3, and Cp at baseline and monthly. Imaging studies are done every 6 months (mos). Results: 28 pts are enrolled and 304 cycles of TM have been administered. Adjuvant: 20 pts, Stage 4 NED: 8 pts, Triple negative: 8 pts (5 stage IV NED, 3 Adjuvant) The median age is 51 years (range: 29-64), median number of positive lymph nodes among Stage III patients is 7 (4-42). The median baseline Cp level was 28 mg/dL (21-43). Among 21 patients who have reached target Cp, the median time to target is 6 weeks (2-16 weeks). Two pts discontinued treatment before reaching target. The median baseline EPCs is 17.38 cells/ml (0.0-286.1) Although there was a trend toward increased EPCs at month 1, this was not statistically significant (p=0.8964) and the majority of pts EPCs were maintained below baseline over time when Cp levels were below target (ie. copper depleted). Toxicity: Grade 3/4 neutropenia occurred in 3 patients (0.02%) with 1 pt with febrile neutropenia. All resolved 5-13 days later with TM held and resumed at a lower dose in 2 patients. No other grade 3/4 toxicity was observed. Three patients were diagnosed with recurrent breast cancer at 1, 9 and 10 mos. An EPC rise preceded an abnormal marker or overt relapse by 3-5 months in 2 of 3 pts. Conclusions: TM is well tolerated in breast cancer patients. TM might contribute to maintaining EPCs below baseline in pts who are copper depleted. We postulate that the increased EPCs noted in both patients with recurrent disease 2-4 months prior to overt relapse could represent the turning on of an angiogenic switch, resulting in an outpouring of CEPCs to the new site of metastasis. Other studies geared toward understanding the mechanism for metastases are underway. The trial continues to accrue.Supported by the Susan B Komen for the Cure, NY Community Trust, Breast Cancer Alliance of Greenwich and the Madeline and Stephen Anbinder Foundation.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6090.

Dasatinib Plus Capecitabine for Advanced Breast Cancer: Safety and Efficacy Data from Phase 1 Study CA180-004

Background: SRC is a potential therapeutic target in breast cancer and has a central role in hormone therapy resistance and in osteoclast activity. Dasatinib is a potent SRC inhibitor that inhibits breast cancer cell proliferation and migration in vitro, including synergy with 5FU in some cell lines, and inhibits osteoclast activity in clinical trials. CA180-004 is a phase 1 study designed to identify dose-limiting toxicities (DLT) and recommended phase 2 doses of dasatinib plus capecitabine in women with advanced breast cancer (ABC). Safety and efficacy data are now reported with additional follow-up.Methods: Cohorts of pts with ABC were treated at four dose levels (DL) with capecitabine (mg/m2 twice daily [BID] on D1-14 of 21-day cycles) and dasatinib (mg daily): DL1: capecitabine 825 + dasatinib 50 BID; DL2: capecitabine 825 + dasatinib 70 BID; DL3: capecitabine 1000 + dasatinib 70 BID; DL3a: capecitabine 1000 + dasatinib 100 once daily (QD). All pts had performance status 0-1, prior taxane and/or anthracycline and ≤2 prior chemotherapy-containing regimens for advanced disease. Disease assessments were performed every 6 weeks. DL3a was expanded for further safety and efficacy estimate using best objective response and progression-free survival (PFS) rates.Results: To date, 47 pts with ABC have been treated, 31 in escalation phase plus 16 in expansion (5 too early). Median age was 52 years (range 35-77). Tumor subtypes: 14% were Her2-amplified, 57% ER+ or PR+, 29% triple-negative. Safety was previously reported (ASCO 2009) for escalation phase; no MTD was defined based on DLTs. Of 20 evaluable pts in DL3a, 2 DLTs have been observed: 1 pneumonia, pain and pleural effusion plus 1 diarrhea, neutropenia, vomiting, mucositis and anemia. The most common drug-related adverse events (AEs, any grade) were headache, fatigue/asthenia, nausea/vomiting, diarrhea, hand-foot syndrome (HFS) and pleural effusion. The most common grade 3/4 AEs were fatigue/asthenia, HFS, vomiting and diarrhea. To date, 19 have remained on treatment ≥4 months, including 3 for &gt;1 year. Median duration of treatment (n=42) was 13 weeks; 23 pts have discontinued for progression and 7 for toxicity. Of 38 pts with on-study assessment, 6 had confirmed partial response (treatment durations 17+, 23, 25, 36+, 71, 73 wks), 6 had unconfirmed partial or clinical response (5, 11, 13, 18, 23+, 24 wks), and 9 had prolonged stable disease (16+, 17, 23+, 24+, 25+, 29, 39+, 48+, 63+ wks). Updated efficacy data, including PFS by hormone receptor status, will be presented.Conclusions: Dasatinib and capecitabine combination treatment was well tolerated and encouraging efficacy was observed. Further assessment of this combination is warranted.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3092.

Differences in Breast Cancer Subtypes among Asian-American Women with Invasive Breast Cancer in New York City

Background: Specific breast cancer (BC) subtypes conferring distinct phenotypic and prognostic outcomes have been defined by molecular gene expression arrays. A recent study suggested that differences in BC subtypes exist among ethnic subgroups of Asian women in California. It has also been reported that there are differences in clinical outcomes among Asians with BC in the US, with Filipinos having a worse prognosis compared with other Asians. We sought to determine whether differences in BC subtypes exist among Asians in New York.Methods: Using outpatient registration records from Weill Cornell Breast Center and St. Vincent's Medical Center in New York City, we identified patients who were diagnosed with stage I, II, or III invasive BC between 1997 and 2007 who were of Chinese, Filipino, Japanese or Korean ethnicity. We reviewed pathology records according to an IRB approved protocol and recorded patient data for age, stage, grade, estrogen receptor (ER), progesterone receptor (PR) status, and HER-2/neu at diagnosis. Immunohistochemical surrogates for the four molecularly defined breast cancer subtypes were used according to accepted definitions (Luminal A: ER+Her2-; Luminal B: ER+ Her2+; Her2/neu: Her2+ ER-; Basal-like: ER-PR-, Her2-) Using chi-square analysis, we explored the relationship between ethnicity and BC subtypes.Results: 346 Asian women were identified with invasive breast cancer. Among the Chinese subgroup, 67% were of the Luminal A subtype, 15.3% were Luminal B, 10% were the Her2/neu subtype and 8.5% were Basal-like. Filipinos had a higher proportion of Luminal B cancers compared to the other ethnic groups. Filipinos and Koreans had a higher proportion of the Her2+/ER- subtype compared to Chinese and Japanese (P=0.004 by chi-square test). When considering all Her2/neu positive cancers, Filipinos had a significantly higher proportion of HER-2/neu positivity (46%) compared to Chinese (25%), Japanese (14%) and Korean (29%) groups (P=0.002). Filipinos and Koreans had a higher proportion of ER negative cancers and Grade III cancers compared to Chinese and Japanese (P=0.001 for ER status and P=0.01 for grade). In our series, Korean subjects were significantly younger than the other three ethnic groups (P&lt;0.0001 by AVOVA test).Conclusions: Differences in BC subtypes exist among Asian women with invasive breast cancer in New York. Filipino women are significantly more likely to have HER-2/neu positive BC compared with Chinese, Japanese, and Korean women. Our results are supportive of results from a study in which differences in distribution of Her2/neu positive cancers among Asians in California were seen. Furthermore, these findings provide one explanation for the worse clinical outcome for Filipinos compared with other Asians that has been previously reported.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3067.

A phase I/II study of CR011-vcMMAE, an antibody-drug conjugate, in patients (pts) with locally advanced or metastatic breast cancer (MBC)

1067

Background: Glycoprotein NMB (GPNMB), also known as osteoactivin, has been shown to regulate metastasis of breast cancer in vivo. CR011-vcMMAE, a fully-human monoclonal anti-GPNMB antibody conjugated to the tubulin inhibitor monomethylauristatin E, is safe and active in pts with advanced melanoma. This is the first study of CR011-vcMMAE in breast cancer. Methods: Eligible pts with MBC had ≥ 2 prior chemotherapy regimens, including a taxane, an anthracycline, and capecitabine; and ECOG PS ≤ 2. Doses were escalated to 1.88 mg/kg IV q3w (the maximum tolerated dose [MTD] in melanoma) using a standard 3+3 design. Immunohistochemistry (IHC) with goat polyclonal antibody to GPNMB was performed on pt biopsy specimens and on tissue microarrays containing normal breast, DCIS, breast tumor and lymph node metastases. Results: 10 pts with MBC (median age 57, range 36 - 69) had a median of 7 prior regimens and were treated with CR011-vcMMAE for a median of 2 cycles (range 1–4). In the first 2 pts at 1.34 mg/kg, dose limiting toxicity of worsening peripheral sensory neuropathy was observed. Pts with baseline neuropathy worse than grade 1 were subsequently excluded. Pts were treated at 1.0 mg/kg (n = 3), 1.34 mg/kg (n = 5), and 1.88 mg/kg (n = 2); enrollment at 1.88 mg/kg is continuing. Other adverse events (AEs) were grade 1/2 anorexia and pain in 4 pts; diarrhea, rash, fatigue, and neuropathy in 3 pts; and grade 3 rash in 1 pt. Evidence of antitumor activity has been observed. A response of 37% tumor shrinkage was seen in a pt after only 2 cycles and is ongoing. A second pt had a 51% reduction after 2 cycles, but had PD after 12 weeks. Breast tumor samples were more likely to stain positive for GPNMB than normal breast tissues. Conclusions: CR011-vcMMAE 1.34 mg/kg IV q3w is well-tolerated in heavily pretreated pts with MBC. The 1.88 mg/kg q3w dose is being assessed and phase II expansion is planned at the MTD. IHC of pt tumor specimens is being evaluated.

[Table: see text]

Phase II trial of the farnesyltransferase inhibitor tipifarnib plus fulvestrant in hormone receptor-positive metastatic breast cancer: New York Cancer Consortium Trial P6205

BACKGROUND

Fulvestrant produces a clinical benefit rate (CBR) of approximately 45% in tamoxifen-resistant, hormone receptor (HR)-positive metastatic breast cancer (MBC) and 32% in aromatase inhibitor (AI)-resistant disease. The farnesyltransferase inhibitor tipifarnib inhibits Ras signaling and has preclinical and clinical activity in endocrine therapy-resistant disease. The objective of this study was to determine the efficacy and safety of tipifarnib-fulvestrant combination in HR-positive MBC.

PATIENTS AND METHODS

Postmenopausal women with no prior chemotherapy for metastatic disease received i.m. fulvestrant 250 mg on day 1 plus oral tipifarnib 300 mg twice daily on days 1-21 every 28 days. The primary end point was CBR.

RESULTS

The CBR was 51.6% [95% confidence interval (CI) 34.0% to 69.2%] in 31 eligible patients and 47.6% (95% CI 26.3% to 69.0%) in 21 patients with AI-resistant disease. A futility analysis indicated that it was unlikely to achieve the prespecified 70% CBR. Tipifarnib dose modification was required in 8 of 33 treated patients (24%).

CONCLUSIONS

The target CBR of 70% for the tipifarnib-fulvestrant combination in HR-positive MBC was set too high and was not achieved. The 48% CBR in AI-resistant disease compares favorably with the 32% CBR observed with fulvestrant alone in prior studies and merit further clinical and translational evaluation.

The effect of tetrathiomolybdate on circulating endothelial progenitor cells in patients with breast cancer at high risk of recurrence

Abstract #1036

Background: Endothelial progenitor cells are critical to tumor angiogenesis and are increased in breast cancer patients. Copper is required for angiogenesis, and pre-clinical data suggest that tetrathiomolybdate (TM), a copper-depleting compound, inhibits angiogenesis and maintains tumor dormancy. We sought to measure circulating endothelial progenitor cells (CEPCs) in patients at high risk of breast cancer recurrence and to evaluate the effect of copper depletion on CEPCs.&#x2028; Methods: This analysis is part of an ongoing phase II study of TM in breast cancer patients at high risk of recurrence defined as Stage III or IV with no evidence of disease. All therapy other than hormonal was completed at least 6 weeks prior to study. Treatment: TM 180 mg daily to achieve a target ceruloplasmin (Cp) level of 5-15 mg/dL (copper depletion), and then 100 mg daily. We monitored levels of CEPCs (CD45dim, CD133+, VEGFR2+), CEA, CA15-3, and Cp at baseline and monthly. CEPCs were also measured in 6 healthy controls.&#x2028; Results: To date we have enrolled 16 patients with a median age of 51 years (range: 29-64). 14 had a history of Stage III disease, while 2 were considered to be Stage IV with no evidence of disease. The median number of positive lymph nodes among Stage III patients was 7 (1-42), with 2 patients having received neoadjuvant therapy. The median baseline Cp level was 28 mg/dL (21-41). Among 12 patients who have reached target Cp, the median time to target was 1 month (1-3 months). The median follow-up of the 4 patients who have not yet achieved target is 2.5 months. 1 of these discontinued treatment before reaching target. The median baseline CEPCs was lower in patients than healthy controls: 0.022 cells/μL (0.000-0.286) vs. 0.123 cells/μL (0.058-0.418); p=0.03. There was no statistically significant change in CEPCs from baseline over time.&#x2028; One patient was diagnosed with recurrent breast cancer at month 10. A rise in her CEPCs preceded a rise in a CEA and overt relapse by 1 and 5 months, respectively.&#x2028; Toxicity: Grade 3/4 neutropenia occurred in 3 patients. TM was held, and this resolved 5-13 days later, after which TM was resumed. No other grade 3/4 toxicity was observed. One patient discontinued TM due to diarrhea attributed to the lactose used in the compounding of TM.&#x2028; Conclusions: TM is well tolerated in breast cancer patients. We postulate that the increased CEPCs noted in one patient at month 4, 6 months prior to overt relapse, could represent the “turning on” of an angiogenic switch, resulting in an outpouring of CEPCs to the new site of metastasis. The trial is ongoing, and with additional follow-up other trends might emerge.&#x2028; Supported by Komen for the Cure Foundation, Anbinder Foundation, NY Community Trust and Breast Cancer Alliance of Greenwich.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1036.

Kinetics of amoxicillin and clavulanate degradation alone and in combination in aqueous solution under frozen conditions

Kinetics of the reactions of amoxicillin sodium and potassium clavulanate alone and in combination were investigated in the frozen state at selected pH values of 2.0, 4.6 and 7.0. Extrapolation of the rate constant values to the frozen state from the liquid state data indicated marked acceleration of the rates of amoxicillin and clavulanate degradation for the pH values investigated. The highest acceleration in rate recorded was 15.0-fold for clavulanate and the lowest value was 4.6-fold for amoxicillin at -7.3 degrees C in the hydrochloric acid system. The rate constant values obtained were interpreted in terms of the concentration model [Pincock, R.E., Kiovsky, T.E., 1966. Kinetics of reactions in frozen solution. J. Chem. Educ. 43, 358-360], phase-temperature relationship of the solutes, buffer catalysis, pH change and polymerization reactions. A kinetic model was deduced for the hydrochloric acid system providing adequate explanation of the experimental results. A large stabilizing effect of sodium chloride used for maintaining constant ionic strength (micro=0.5) was evident in this system. The shelf-life of amoxicillin was increased from 2.2 to 58.7h at -7.3 degrees C when sodium chloride was included in the hydrochloric acid system.

Phase II study of eribulin mesylate (E7389) halichondrin b analog in patients with refractory breast cancer

1034

Background: Eribulin is a structurally simplified analog of halichondrin B, which inhibits microtubule dynamics via a novel mechanism characterized by suppression of microtubule growth, lack of effect on microtubule depolymerization, and sequestration of tubulin into nonfunctional aggregates. This study was designed to assess the activity and tolerance of eribulin in chemotherapy refractory patients with advanced breast cancer. Methods: Eribulin was evaluated in a single-arm Phase II trial in female patients with refractory breast cancer, ECOG performance status of 0–1, measurable disease, and neuropathy ≤ Grade 2. Patients received ≥ 1 prior chemotherapy regimen, including an anthracycline and a taxane. Eribulin was administered as a 2–5 min IV bolus of 1.4 mg/m2 on Days 1, 8, and 15 of a 28-Day cycle (Group 1). The schedule was modified to Days 1 and 8 of a 21-Day cycle (Group 2), because of dose delays. The primary efficacy endpoint was ORR according to RECIST criteria based upon independent review (IR) of tumor assessment. Results: Of 104 patients enrolled, 103 received eribulin treatment: 70 in Group 1, 33 in Group 2. Median age was 55 yrs (range 32–84). Patients had received a median of 4 prior chemotherapy regimens (range 1–11). Sixty-one percent of tumors were ER+, 14% Her2/neu 3+, and 29% were triple (ER, PR, Her-2) negative. The incidence of dose interruption, delay, or omission during Cycle 1 was 63% (Group 1) and 18% (Group 2). The most common drug related toxicities were neutropenia (75%, Grades 3: 31%, Grade 4: 30%, febrile neutropenia: 3.9%), fatigue (52%, Grade 3: 2.9%, no Grade 4), alopecia (Grade 1/2: 41%), nausea (37%, Grade 3: 1%, no Grade 4), and anemia (36%, Grade 3: 1%, no Grade 4). Peripheral neuropathy occurred in 34% of patients (Grade 3: 3.9%, no Grade 4). Best overall response rate (all PR) by IR was 14.5% and 15.2% in Groups 1 and 2, respectively; the combined ORR was 14.7% (95 % CI: 9–23%). Median PFS was 85 days, and the 6 mo PFS rate was 31%. Conclusions: Eribulin given as a 2–5 min IV infusion on Days 1, 8 of a 21-Day cycle or Days 1, 8, 15 of a 28-Day cycle exhibited a 15% PR rate by IR and a low incidence of Grade 3 neuropathy in this heavily chemotherapy pretreated population. The most common toxicity was neutropenia. The 21-Day schedule had an acceptable toxicity profile.

No significant financial relationships to disclose.

Phase I clinical trial of ixabepilone and pegylated liposomal doxorubicin in patients with advanced breast or ovarian cancers: New York Cancer Consortium Trial P7229

2570

Background: Ixabepilone (IX) is a semisynthetic epothilone B analog with activity in patients (pts) with taxane refractory cancer. Two phase III clinical trials in breast cancer (BC) and a phase II study in ovarian cancer (OC) have recently been completed. Pegylated liposomal doxorubicin (PLD) is used for the treatment of platinum refractory OC and has activity in patients with metastatic BC. Methods: We have completed enrollment of a phase I study of PLD IV and ixabepilone IV over 3 hours. 18 pts with metastatic cancer (10 BC and 8 OC) with median age 51 were enrolled from 1/13/06 to 12/22/06. A total of 60 cycles has been administered to date. 3 OC patients enrolled at dose level 3 have not yet completed 2 cycles of treatment and are not yet evaluable. Results: Dose limiting toxicities (DLT) based on toxicities experienced during the first 2 cycles is provided in the table below. Adverse events (AE) occurring in any cycle were: Grade 4 AE: neutropenia < 7 days (1 pt). Grade 3 AE: palmar plantar erythrodysesthesia (PPE) (4), mucositis (3), infection (2), fatigue (2), neutropenia (2), thrombocytopenia (2), anemia (1), neuropathy (1), bilirubin (1). Non-hematological grade 2 AEs included: mucositis (4), PPE (3), infection (2), neuropathy (2), rash (3), pain (3), fever (1), myalgias (1), and anorexia (1). Responses so far for 10 BC pts are PR (1) SD (3) PD (6) and for 5 OC pts are PR (1) SD (2) PD (2). Updated results will be presented. Conclusions: Although the recommended phase II dose when given every 3 weeks is 30 mg/m2 for PLD and 32 mg/m2 for IX by our criteria, PPE and mucositis became problematic when treatment was continued beyond 2 cycles. We are therefore exploring a 4 week PLD schedule, evaluating IX given either every 4 weeks (as shown) or weekly (on days 1, 8, and 15). A phase II trial of the combination in platinum refractory OC will be initiated upon completion of the phase I. Supported by N01-CM-62204

[Table: see text]

[Table: see text]

Randomized trial of low-dose interleukin-2 vs cyclosporine A and interferon-γ after high-dose chemotherapy with peripheral blood progenitor support in women with high-risk primary breast cancer

High-risk primary breast cancer patients treated with high-dose chemotherapy (HDC) and stem cell support (SCS) have shown prolonged disease-free survival (DFS) in many studies; however, only one trial has demonstrated an overall survival benefit (OS). We hypothesize that the period following myeloablative therapy is ideal for immunologic manipulation and studied the effects of two different methods of immunotherapy following HDC with SCS aimed at the window of immune reconstitution. Seventy-two women with high-risk stage II or III breast cancer were randomized following HDC to receive either interleukin 2 (IL-2) at 1 million units/m(2) SQ daily for 28 days or combined cyclosporine A (CsA) at 1.25 mg/kg intravenously daily from day 0 to +28 and interferon gamma (IFN-gamma) 0.025 mg/m(2) SQ every 2 days from day +7 to +28. At a median follow-up of 67 months, no significant difference was observed in DFS or OS between the two treatment groups. The IL-2 arm had a 59% DFS (95% CI (0.45, 0.78)) and a 72% OS (95% CI (0.58, 0.88)) at 5 years. The CsA/INF-gamma arm had a similar outcome with a 55% DFS (95% CI (0.40, 0.76)) and a 78% OS (95% CI (0.65, 0.94)) at 5 years. Treatment was well tolerated, without increased toxicity.

Circulating endothelial progenitor cells correlate to stage in patients with invasive breast cancer

616

Background: Tumor growth and metastasis is dependent on neo-angiogenesis. Both pre-existing and circulating vascular cells have been shown to contribute to the assembly of tumor neo-vessels in specific tumors. Mobilization of endothelial progenitor cells (EPCs) from the bone marrow constitutes a crucial step in the formation of de novo blood vessels, and levels of peripheral blood EPCs have been shown to be increased in certain malignant states. However, the role of circulating EPCs in breast cancer is largely unknown. Methods: We recruited twenty-five patients with biopsy-proven invasive breast cancer (BC) at Weill Cornell Breast Center to participate in a pilot study investigating the correlation of circulating EPCs to extent of disease and initiation of chemotherapy. For each patient, a baseline sample was drawn before systemic treatment, and for seventeen of those patients, a second sample was taken after the first round of chemotherapy. Levels of peripheral blood EPCs, as defined by co-expression of CD133 and VEGFR2, were quantified by flow cytometry. Results: BC patients with stage III & IV disease had statistically higher levels of circulating EPCs than did patients with stage I & II disease (median=165,000 EPCs/5×106MNCs vs. median=6,920 EPCs/5x106MNCs, respectively, p < 0.0001 by Wilcoxon rank-sum test). In addition, in late-stage patients, levels of EPCs demonstrated a statistically significant drop after initiation of chemotherapy (median=162,500 EPCs/5x106MNCs [pre] vs. median=117,500 EPCs/5x106MNCs [post], p = 0.01 by Wilcoxon signed-rank test). Conclusion: These results suggest that circulating EPCs may serve as a potential tumor biomarker in breast cancer and that EPCs may represent a plausible target for future therapeutic intervention. Supported in part by the Mentored Medical Student in Clinical Research Program (General Clinical Research Center/National Institutes of Health Grant M01RR00047), Madeline & Stephen Anbinder Clinical Scholar Award, and Anne Moore Breast Cancer Research Fund

No significant financial relationships to disclose.