Targeting HER2-positive metastatic breast cancer with ARX788, a novel anti-HER2 antibody-drug conjugate in patients whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens

TPS1112

Background: The overexpression and/or amplification of human epidermal growth factor receptor 2 (HER2) occurs in approximately 20% of breast cancers (BC) and is a major driver of tumor development and progression. This HER2 subtype confers aggressive tumor behavior and the HER2 receptor remains a valuable target for antibodies, bi-specifics, and antibody drug conjugates (ADC). With advances in targeted therapy, patients with HER2-positive breast cancer (HER2+ BC) may experience an improved prognosis, including survival. Novel HER2-targeted therapies are being investigated to overcome drug resistance and to help mitigate adverse events (e.g., cardiotoxicity). ARX788 is a next-generation ADC using a technology platform whereby a HER2 specific monoclonal antibody is conjugated with Amberstatin269 (AS269), a potent cytotoxic tubulin inhibitor. Site-specificity, high homogeneity, and stable covalent conjugation of ARX788 leads to its slow release and prolonged peak of serum pAF-AS269, which may contribute to the lower systemic toxicity and increased targeted delivery of payload to tumor cells at a lower effective dose compared to other HER2 ADCs. Clinical activity has been seen in Phase I HER2 breast and pan-tumor studies. Methods: Trial Design: ACE-Breast-03 (NCT04829604) is a global, phase 2 study designed to assess anticancer activity and safety of ARX788 in patients with metastatic HER2 positive breast cancer. Patients whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens are eligible. Patients must have adequate organ function. Any brain metastases must be radiographically stable without steroid dependence. Efficacy will be assessed using Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 by imaging every 6 weeks on study. Endpoints include objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), best overall response (BOR), duration of response (DOR), and time to response (TTR). The safety and tolerability profile will be evaluated. Blood samples will be collected at specified time points to determine serum concentrations of ARX788, total antibody, and metabolite pAF-AS269. Potential predictive and/or prognostic biomarkers at baseline and on-treatment will be analyzed for exploratory purposes. Descriptive statistics will be used to evaluate anticancer activity, safety, and tolerability. The study is currently recruiting patients. Please contact breast03trialinquiry@ambrx.com for additional information. Clinical trial information: NCT04829604.

Cardiac safety of dual anti-HER2 blockade with pertuzumab plus trastuzumab (P+T) in the APHINITY trial

510

Background: Trastuzumab (T) increases the incidence of cardiac events (CEs) in patients (pts) with early breast cancer (BC). Dual blockade with P+T improves BC outcomes and is the standard of care for high-risk HER2-positive BC pts following the phase 3 APHINITY trial that evaluated the addition of P or placebo (Pla) to T and chemotherapy (CT). We analyzed the cardiac safety of P+T in APHINITY. Methods: APHINITY eligibility required a left ventricular ejection fraction (LVEF) ≥55% at study entry. LVEF assessment was performed every 3 months (mos) during treatment, every 6 mos up to month 36, and yearly thereafter. Primary CE was defined as heart failure (HF) class III/IV and a significant decrease in LVEF of at least 10 percentage points from baseline and to <50%, or cardiac death. Secondary CE was defined as a confirmed significant decrease in LVEF or CEs confirmed by the cardiac advisory board. Results: The safety analysis population consists of 4,769 pts. With 74 mos median follow-up (FU), CEs were observed in 159 pts (3.3%): 83 (3.5%) in the P+T and 76 (3.2%) in Pla+T arms, respectively. Most CEs occurred during anti-HER2 therapy: 123/159 (77.4%) and were asymptomatic or mildly symptomatic LVEF decrease (133/159; 83.6%) (Table 1). There were 2 cardiac deaths in each arm (0.1%). More CEs occurred in pts receiving an anthracycline-based CT compared to those receiving non-anthracycline CT (139 vs. 20 CEs, respectively). Acute recovery from a CE based on subsequent LVEF values was observed in 127/155 pts (81.9%). Conclusions: Dual blockade with P+T does not increase the risk of CE compared to Pla+T alone. The use of anthracycline-based CT increases the risk of a CE; hence non-anthracycline CT may be considered particularly in pts with other cardiovascular risk factors. Clinical trial information: NCT01358877. [Table: see text]

Updated overall survival (OS) results from the phase III MONALEESA-3 trial of postmenopausal patients (pts) with HR+/HER2- advanced breast cancer (ABC) treated with fulvestrant (FUL) ± ribociclib (RIB)

1001

Background: The Phase III MONALEESA-3 trial (NCT02422615) previously demonstrated a statistically significant improvement in OS with RIB, a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i), plus FUL compared with placebo (PBO) plus FUL as first-line (1L) or second-line (2L) treatment in postmenopausal pts with HR+/HER2− ABC (median, not reached vs 40.0 mo; hazard ratio [HR], 0.72; 95% CI, 0.57-0.92, P =.00455). This analysis was final per the protocol; following the unblinding of the study, pts still on study treatment in the PBO arm were allowed to cross over to the RIB arm. We report an exploratory analysis of OS after an additional median 16.9 mo of follow-up, allowing for further characterization of long-term survival benefits of RIB. Methods: Postmenopausal pts with HR+/HER2− ABC were randomized 2:1 to receive RIB + FUL or PBO + FUL in 1L and 2L settings. Updated OS was evaluated by Cox proportional hazards model and summarized using Kaplan-Meier methods. Additional postprogression endpoints such as progression-free survival 2 (PFS2), time to chemotherapy (CT), and CT-free survival were also evaluated and summarized. Results: At the data cutoff (Oct 30, 2020), the median follow-up was 56.3 mo (min, 52.7 mo) and 68 (14.0%) and 21 (8.7%) patients were still on treatment in the RIB vs PBO arms, respectively. With this extended follow-up, RIB + FUL continued to demonstrate an OS benefit vs PBO + FUL (median, 53.7 vs 41.5 mo; HR, 0.73; 95% CI, 0.59-0.90). RIB + FUL had prolonged OS vs PBO + FUL in the 1L (median, not reached vs 51.8 mo; HR, 0.64; 95% CI, 0.46-0.88) and 2L subgroups (median, 39.7 vs 33.7 mo; HR, 0.78; 95% CI, 0.59-1.04). Subgroup analyses also showed a consistent OS benefit compared with the intent-to-treat (ITT) population for most subgroups. PFS2, time to CT, and CT-free survival for the ITT population favored RIB + FUL (Table). Among pts who discontinued study treatment, 81.9% and 86.4% received a next-line subsequent antineoplastic therapy, while 14.0% and 30.0% received a CDK4/6i as any subsequent line in the RIB vs PBO arms, respectively. No new safety signals were observed. Conclusions: The previously demonstrated robust and clinically meaningful OS benefit with RIB + FUL compared with PBO + FUL was maintained after almost 5 years of follow-up in postmenopausal pts with HR+/HER2− ABC. The OS benefit of RIB was observed in the 1L and 2L subgroups, which further supports the use of RIB in these populations. The results also demonstrated a significant delay in the use of subsequent CT with RIB vs PBO. Clinical trial information: NCT02422615 .[Table: see text]

Trastuzumab deruxtecan (T-DXd) in patients with HER2+ metastatic breast cancer with brain metastases: A subgroup analysis of the DESTINY-Breast01 trial

526

Background: Patients (pts) with HER2+ metastatic breast cancer (mBC) are at high risk of developing brain metastases (BMs), and treatment options are limited once BMs occur. T-DXd is an antibody-drug conjugate composed of an anti-HER2 antibody, a cleavable tetrapeptide-based linker, and a topoisomerase I inhibitor payload. On the basis of findings of the phase 2 DESTINY-Breast01 trial (NCT03248492), T-DXd was approved for the treatment of adult pts with HER2+ unresectable or mBC who have received ≥2 prior anti-HER2–based regimens (US and Europe) or had prior chemotherapy and are refractory to or intolerant of standard treatments (Japan). Here we describe a subgroup analysis from DESTINY-Breast01 in pts with a history of BMs. Methods: DESTINY-Breast01 is an ongoing, 2-part, multicenter, open-label, phase 2 trial of T-DXd in adult pts with HER2+ unresectable or mBC previously treated with trastuzumab emtansine. Pts with baseline BMs that were treated, asymptomatic, and did not require therapy to control symptoms were eligible for enrollment. All treatment to control symptoms had to be completed ≥60 days before randomization. An MRI of the brain every 6 wks was only required for pts with BMs at baseline. Brain lesions were considered non-target lesions, and thus collection of diameter measurements was not required. This analysis includes pts with a history of BMs at baseline who received T-DXd at the approved dose of 5.4 mg/kg every 3 wks. Results: Twenty-four pts with a history of BMs were included (data cutoff, August 1, 2019). In these pts, the objective response rate (ORR), median progression-free survival (mPFS), and median duration of response (mDoR) per independent central review with T-DXd 5.4 mg/kg were 58.3% (95% CI, 36.6%-77.9%), 18.1 mo (95% CI, 6.7-18.1 mo), and 16.9 mo (95% CI, 5.7-16.9 mo), respectively, and were comparable to those in the total pt population (N = 184) treated at 5.4 mg/kg in the DESTINY-Breast01 study (ORR, 60.9%; mPFS, 16.4 mo; mDoR, 14.8 mo; median follow-up, 11.1 mo). The pattern of disease progression was similar in pts with and without BMs with 8 of 24 pts having progressed (33%; 2 in the brain) in the BMs subgroup and 40 of 160 pts (25%; 2 in the brain) in the non-BMs subgroup, suggesting durable systemic disease control. Baseline diameters of BMs were available for 14 of 24 pts (radiotherapy prior to study enrollment was reported in 12 of 14). Among the pts with information available on baseline BM diameter, the central nervous system response rate per investigators was 50% (7 of 14 pts). Conclusions: T-DXd showed strong clinical activity in both the overall population of pts with HER2+ mBC and the subgroup of pts with BMs. The demonstrable response of BMs to treatment and durable clinical activity of T-DXd in pts with a history of BMs at baseline are promising and warrant further investigation. Clinical trial information: NCT03248492.

Impact of leucocyte modifications in patients with locally advanced cervical treated by chemoradiotherapy

e18014

Background: Concomitant cisplatin-based chemoradiotherapy (CCRT), followed by image guided-adaptive brachytherapy (IGABT) is the recommended treatment for patients suffering from locally advanced cervical cancer (LACC). Methods: Between January 2010 and May 2017, 103 patients with LACC (FIGO 2009-stages IB2-IVA) received CCRT followed by IGABT. The objectives of this study were to evaluate the impact of white blood cells (WBC) and polymorphonuclear neutrophils (PMN) counts variations on outcomes. This variable was calculated by substraction between WBC or PMN levels at the first cycle (CB) and the last cycle (CL) of chemotherapy (CT)(DCB-CL). The data were reviewed retrospectively, with Cox regression for univariate and multivariate analysis. Results: The median age at diagnosis was 50 years. The median tumor size at diagnosis was 47mm. The majority of the patients had FIGO stage II (60.2%) or stage I (21.4%) disease with squamous histology (88.3%). Patients received a median dose of external-beam radiotherapy (EBRT) of 45 Gy (range 40-50.4 Gy) by 1.8-2 Gy fractions, with a median cumulative dose of all the radiotherapy of 85 Gy. The median duration of EBRT+IGABT was 51 days (range 31-94). All patients received at least one cycle of cisplatin, but the majority received 5 (40.4%) or 6 (39.4%) cycles. The median follow-up time for all patients was 30.1 months. The overall survival (OS) and recurrence-free survival (RFS) at 3 years was 81,4% and 76,8% respectively. Univariate analysis associated higher DCB-CL WBC and DCB-CL PMN with better OS and RFS. Multivariate analysis confirmed that DCB-CL WBC (HR, 0.856; 95% CI, 0.737-0.986; p = 0.018) and DCB-CL PMN (HR, 0.863; 95% CI, 0.750-0.994; p = 0.041) were associated with better OS and RFS respectively. A linear regression analysis was performed to cross the DCB-CL WBC/PMN and the number of CT cycles. This analysis reveals that an increasing number of CT cycles is linked to an increased DCB-CL WBC/PMN. Conclusions: Our study reveals the impact of DCB-CL WBC and PMN on outcomes. These two tests could become biomarkers during CCRT to discuss adjuvant treatments, but also to adapt our follow-up.

Acquired genomic alterations in circulating tumor DNA from patients receiving abemaciclib alone or in combination with endocrine therapy

3519

Background: An understanding of the mechanisms of acquired resistance to CDK4 & 6 inhibitors, either alone or with endocrine therapy (ET), is an unmet need. Abemaciclib is a CDK4 & 6 inhibitor approved for treatment of HR+, HER2- advanced breast cancer (ABC). Here we evaluated acquired genomic alterations detected in circulating tumor DNA (ctDNA) from patients (pts) treated with abemaciclib + nonsteroidal aromatase inhibitor (AI) or placebo + AI in MONARCH 3 or abemaciclib monotherapy in nextMONARCH 1. Methods: MONARCH 3 randomized postmenopausal women with HR+, HER2- ABC with no prior systemic therapy in the advanced setting to abemaciclib (150 mg Q12H) or placebo + AI. nextMONARCH 1 randomized women with HR+, HER2- metastatic breast cancer who had progressed on or after prior ET and CT to abemaciclib (150 mg Q12H) + tamoxifen, abemaciclib (150 mg Q12H), or abemaciclib (200 mg Q12H) + loperamide. Plasma from pts in the abemaciclib or placebo + AI arms (MONARCH 3) or abemaciclib monotherapy arms (nextMONARCH 1) was analyzed by the Guardant360 assay to identify potential tumor-related genomic alterations including point mutations, indels, amplifications, and fusions acquired at EOT in comparison with baseline. Results: For MONARCH 3, commonly acquired alterations at EOT included ESR1 (17%), TP53 (10%), EGFR (8%), FGFR1 (7%), and PDGFRA (7%) in the abemaciclib + AI arm, and ESR1 (31%), TP53 (10%), and BRCA1 (7%) in the placebo + AI arm. Acquired alterations more frequent for abemaciclib + AI pts included RB1 (6%), MYC (5%), and AR (5%), compared to 0% in the placebo + AI arm (p = 0.008 RB1; p = 0.015 MYC or AR). In contrast, acquired ESR1 alterations were less frequent with abemaciclib + AI vs placebo + AI (17% vs 31%, p = 0.038). In nextMONARCH 1, the most commonly acquired alterations with abemaciclib monotherapy were in TP53 (10%), EGFR (9%), RB1 (9%), MYC (9%), and MET (8%). In addition, acquired alterations in ESR1 (6%) and AR (3%) were also found. PIK3CA alterations were not frequently acquired (abemaciclib + AI 1%, placebo + AI 6%, abemaciclib monotherapy 5%). Conclusions: Acquired genomic alterations potentially associated with emerging mechanisms of resistance to abemaciclib alone or in combination with AI may include RB1, MYC, or AR alterations, while the acquisition of ESR1 alterations was less common in pts treated with abemaciclib + AI compared to placebo + AI. These findings are hypothesis-generating and provide insight into mechanisms of resistance to abemaciclib vs ET. Clinical trial information: NCT02246621, NCT02747004 .

Updated overall survival and safety profile of durvalumab monotherapy in advanced NSCLC

169

Background: Single-agent durvalumab is being evaluated in patients with advanced squamous and non-squamous NSCLC in an ongoing Phase 1/2 study (NCT01693562). Here we present updated survival and safety data in NSCLC patients. Methods: Treatment-naïve (1L) and previously treated (2L or 3L+) stage IIIB/IV NSCLC patients received durvalumab 10 mg/kg Q2W for up to 12 months. Patients were stratified by tumor PD-L1 expression (Ventana PD-L1 [SP263] Assay [PD-L1 high: ≥25% of tumor cells with membrane staining]), treatment line, and histology. Results: As of 05 September 2017, 304 NSCLC patients received durvalumab monotherapy. Median duration of follow-up was 35.6 (0.3–50.9) months. Investigator-assessed ORR ranged between 23.2% and 30.0% among PD-L1 high patients, and between 3.6% and 8.3% among PD-L1 low/negative patients. Median PFS and median OS were longer in PD-L1 high vs PD-L1 low/negative patients (Table). Any-grade treatment-related AEs (TRAEs) were reported in 57.2% of pts (including fatigue, 17.4%, decreased appetite, 9.2%, diarrhea, 8.9%); in 10.2% of pts these were Grade 3 or 4. TRAEs resulting in treatment discontinuation were reported in 17 patients (5.6%); 1 patient had a Grade 5 TRAE (pneumonia). Conclusions: In this ongoing phase 1 study, OS and safety profile appear encouraging in treatment-naïve and previously treated NSCLC patients, particularly among PD-L1 high patients. Further investigation regarding PD-L1 expression for selection of patients who most likely benefit from durvalumab is needed. Clinical trial information: NCT01693562. [Table: see text]

Combination of paclitaxel and LAG3-Ig (IMP321), a novel MHC class II agonist, as a first-line chemoimmunotherapy in patients with metastatic breast carcinoma (MBC): Interim results from the run-in phase of a placebo controlled randomized phase II

1062

Background: IMP321 is a recombinant soluble LAG3-Ig fusion protein that binds to MHC class II molecules and mediates antigen-presenting cell (APC) activation followed by CD8 T-cell activation. The activation of the dendritic cell network with IMP321 the day after a low dose injection of a single agent chemotherapy may lead to stronger anti-tumor CD8 T-cell responses. We report initial results of the safety run-in of a randomized, placebo-controlled phase IIb trial in patients (pts) with hormone receptor positive (HR+) MBC receiving first-line weekly paclitaxel. Methods: In the safety run-in phase 15 pts with MBC received weekly paclitaxel (80 mg/m2; D1, D8, D15) in a four week cycle in conjunction with either 6 mg (n = 6; cohort 1) or 30 mg (n = 9, cohort 2) IMP321 injections s.c. (D2 and D16) for 6 cycles. Patients without progressive disease could continue with a maintenance phase of 12 additional injections of IMP321 every 4 weeks. Blood samples for pharmacokinetics and immuno-monitoring were taken in cycle 1 and 4 just before and after IMP321 injection. Results: In total 15 pts (median age 53 years) were enrolled between Jan 2016 and Oct 2016. No dose limiting toxicities have been reported. Cytokine release syndrome grade 1 was the only serious adverse event (SAE) related to IMP321 and occurred twice in the same patient. Grade 1 and 2 injection site reactions were the most common related AEs and occurred in 14 pts (93 %). A dose-dependent increase in serum IMP321 concentration was observed among the two dose levels with a Cmaxbetween 4 and 24 hours. Increased number of circulating monocytes, dendritic cells and increased activation were observed at both dose levels of IMP321, supporting the working hypothesis. Conclusions: The 30 mg s.c. IMP321 given every two weeks in combination with weekly paclitaxel is the recommended phase 2 dose which is used in the ongoing randomized placebo controlled phase II part of the study. Clinical trial information: NCT02614833.

SOLE (Study of Letrozole Extension): A phase III randomized clinical trial of continuous vs intermittent letrozole in postmenopausal women who have received 4-6 years of adjuvant endocrine therapy for lymph node-positive, early breast cancer (BC)

503

Background: In animal models of hormone receptor positive (HR+) breast cancer, acquired resistance to continued letrozole was shown to be reversed by estrogen-induced apoptosis. Sensitization to reintroduction of estrogen withdrawal by letrozole was hypothesized to improve treatment outcome. SOLE tested the hypothesis that 3 mos treatment-free intervals during extended adjuvant therapy will improve disease-free survival (DFS). Methods: SOLE enrolled 4884 postmenopausal women with HR+ lymph node-positive BC who had completed 4-6 yrs of adjuvant endocrine therapy (19% SERM, 43% AI, 38% both; stratification factor). Pts were randomly assigned to an additional 5 yrs continuous letrozole (2.5 mg daily; n = 2441) vs 5 yrs intermittent letrozole (taken for the first 9 mos of yrs 1-4, and 12 mos in yr 5; n = 2443). The primary endpoint was DFS (randomization until invasive local, regional, distant recurrence or contralateral BC; 2nd malignancy; death). Final analysis was at 665 DFS events, after 2 interim analyses. SOLE required 4800 pts for 80% power to detect a 20% DFS hazard reduction with 2-sided α = 0.05 using a stratified log rank test. Analysis is by intention-to-treat. Results: At 60 mos median follow-up, 5 yr DFS from randomization was 85.8% vs 87.5% for patients assigned intermittent vs continuous letrozole (HR = 1.08; 95% CI 0.93-1.26; P = 0.31). Similar outcome was observed for breast cancer-free interval (HR = 0.98; 95% CI 0.81-1.19), distant recurrence-free interval (HR = 0.88; 95% CI 0.71-1.09), and overall survival (HR = 0.85; 95% CI 0.68-1.07). AEs of grade > 3 were reported for 43.5% vs 41.6% of pts assigned intermittent vs continuous letrozole. Overall 24% pts discontinued letrozole early in both groups. Conclusions: Among postmenopausal women with HR+ BC, extended intermittent letrozole did not improve DFS vs continuous letrozole. The similar observed outcomes and incidence of AEs provides clinically relevant information on the intermittent administration of extended letrozole for patients who could benefit from temporary treatment breaks. Clinical trial information: NCT00553410.

Updated safety and clinical activity of durvalumab monotherapy in previously treated patients with stage IIIB/IV NSCLC

9085

Background: Preliminary analyses of an ongoing Phase 1/2 study of single-agent durvalumab showed antitumor activity and a tolerable safety profile in advanced NSCLC, with higher ORR and longer OS in pts with high vs. low/negative PD-L1 tumor expression. Here we present updated safety analyses (primary endpoint) for all NSCLC pts and clinical activity based on investigator-assessed RECIST v1.1 in pts who had received prior treatment for advanced NSCLC. Methods: Durvalumab (10 mg/kg q2w) was given until unacceptable toxicity or disease progression, or for up to 12 mos; retreatment was permitted upon disease progression after completion of 12 mos of treatment. PD-L1 expression was assessed using the Ventana PD-L1 (SP263) Assay (PD-L1 high = ≥25% and PD-L1 low/negative = <25% of tumor cells with membrane staining). Results: As of 24 Oct 2016, 245 pts with previously treated NSCLC (53% squamous) received durvalumab and were followed for a median of 29.2 (range 0.3–40.5) mos; 142 pts (58%) had treatment-related adverse events (AEs), most frequent: fatigue (18%), decreased appetite (9%), and nausea, rash, and diarrhea (each 8%). 25 pts (10%) had treatment-related Grade 3/4 AEs, most frequent: fatigue and hyponatremia (each 2%); there were no treatment-related deaths. 4% had treatment-related serious AEs including colitis and pneumonitis (each 2%). In the overall population, 12 mo OS rate was 47% (95% CI 40–53) and 18 mo OS rate was 38% (95% CI 31–45). Antitumor activity and survival by PD-L1 status are shown in the table. Conclusions: Consistent with earlier reports, durvalumab had a manageable safety profile in Stage IIIB/IV NSCLC, with encouraging clinical activity as 2L+ therapy. Higher tumor PD-L1 expression enriched clinical benefit of response rate and survival endpoints. Clinical trial information: NCT01693562. [Table: see text]

Comparative efficacy of everolimus versus fulvestrant for hormone-receptor–positive (HR+) advanced breast cancer (ABC) following progression/recurrence after first-line treatment: A network meta-analysis

e11602

Background: Everolimus (EVE), an oral mammalian target of rapamycin (mTOR) inhibitor, is approved in combination with exemestane (EXE) to treat postmenopausal women (PMW) with HR+, human epidermal growth factor receptor-2–negative (HER2–) ABC that progressed after nonsteroidal aromatase inhibitor therapy. Fulvestrant (FUL), an estrogen receptor antagonist, is another treatment option for PMW previously treated with endocrine therapy. However, the comparative efficacy of EVE + EXE vs FUL is unknown. Methods: Six randomized, controlled trials in HR+, HER2–ABC patients were identified by systematic literature review (Cochrane library, National Horizon Scanning Centre, and NICE Web sites) that formed a network permitting indirect comparisons of EVE + EXE or EVE + tamoxifen (TAM) vs FUL: BOLERO-2, CONFIRM, EFECT, Paridaens (2008), SoFEA, and TAMRAD. All 6 trials had EXE, TAM, or FUL 250 mg as the common comparator to form the network. Relative efficacy of EVE and FUL was obtained using a Bayesian network meta-analysis based on these 6 trials. The primary endpoint was local assessment of progression-free survival (PFS) or time to progression (TTP). The hazard ratio (HR) of EVE + EXE relative to FUL and its 95% credible intervals (CrI) were calculated. Evidence of a difference between treatments is suggested by the 95% CrI not including 1. A HR <1 indicates that the hazard rate is higher in the comparator group and that the treatment is more effective. Results: EVE + EXE was found to be more efficacious for PFS/TTP than FUL 250 mg (HR = 0.47; 95% Crl, 0.38-0.58) and more efficacious than FUL 500 mg (HR = 0.59; 95% Crl, 0.45-0.77). EVE + TAM was found to be numerically better for PFS/TTP than FUL 250 mg (HR = 0.65; 95% Crl, 0.40-1.04) and numerically better than FUL 500 mg (HR = 0.81; 95% Crl, 0.49-1.33). Conclusions: The indirect evidence from this analysis suggests that EVE in combination with EXE is more efficacious than FUL 250 and 500 mg in PMW with HR+, HER2– ABC that progresses after endocrine therapy. These data should be interpreted with caution as there is no randomized trial that directly compares EVE + EXE vs FUL.

Phase III, randomized, double-blind, placebo-controlled multicenter trial of daily everolimus plus weekly trastuzumab and vinorelbine in trastuzumab-resistant, advanced breast cancer (BOLERO-3)

505

Background: Everolimus (EVE) is an inhibitor of mammalian target of rapamycin (mTOR), a protein kinase central to a number of signaling pathways regulating cell growth and proliferation. Data from preclinical and phase 1/2 clinical studies indicated that adding EVE to trastuzumab (TRAS) plus chemotherapy may restore sensitivity to and enhance efficacy of human epidermal growth factor receptor 2 (HER2)-targeted therapy. The international BOLERO-3 phase 3 study is being conducted to evaluate the addition of EVE to TRAS plus vinorelbine. Methods: Adult women with HER2+ advanced breast cancer and who received prior taxane therapy and experienced recurrence or progression on TRAS were randomized 1:1 to receive either EVE or placebo (5 mg/day) in combination with weekly TRAS and vinorelbine (25 mg/m2). The primary endpoint is progression-free survival (PFS). Secondary endpoints included overall survival, response rate, clinical benefit rate, safety, quality of life, and pharmacokinetics. Final analysis will be conducted after approximately 417 PFS events. Results: The trial accrued 569 patients between October 2009 and May 2012. Previous therapy included TRAS (100%), a taxane (100%), and lapatinib (28%). The median age was 54 years, and 76% of patients had visceral metastases, 5% had stable brain metastases, 56% had hormone-receptor–positive disease, 33% had Eastern Cooperative Oncology Group performance status of 1 or 2, and 41% had 3 or more metastatic sites. The median number of prior chemotherapy lines in the metastatic setting was 1. As of February 4, 2013, a total of 396 PFS events were reported. Conclusions: Final PFS analysis will be performed in early May 2013; primary and secondary efficacy endpoints will be presented. Clinical trial information: NCT01007942.

Patterns of resource utilization and cost for postmenopausal women with hormone-receptor–positive (HR+), HER2-negative (HER2–) advanced breast cancer (ABC) in Europe

e17520

Background: Healthcare resource utilization varies by disease stage and treatment choice. Notably, chemotherapy (CT) use is associated with extensive healthcare resource utilization and cost. This study reviews the direct and indirect cost implications of CT versus hormonal therapy (HT) in the ABC setting through the first 3 lines of treatment. Methods: A retrospective chart review of postmenopausal women diagnosed with HR+, HER2– ABC in 5 European countries was conducted. Patients must have progressed on at least 1 line of HT and completed at least 1 line of CT in the ABC setting. Patient cohorts based on therapy received in each line were constructed (cohort A: HT 1st-line, CT 2nd-line, and any treatment 3rd-line; cohort B: HT 1st- and 2nd-line with CT 3rd-line; and cohort C: CT 1st-line with any 2nd- and 3rd-line). Costs of care based on resource utilization and country-specific cost were calculated by patient cohort and line of therapy. Working status was also assessed. Results: A total of 355 eligible patient charts between 2008 and 2012 were included in the analysis: cohort A, 218 (61%) patients; cohort B, 26 (7%) patients; and cohort C 111 (31%) patients. Total direct costs over all 3 treatment lines were €14,362 higher for CT versus HT as 1st-line therapy (cohort C vs A) and €10,368 higher for CT versus HT as 2nd-line (cohort A vs B). Monthly direct costs were €2,536 higher for CT versus HT for 1st-line therapy and €1,713 higher for CT versus HT in 2nd-line. Increased costs for CT were due to treatments to manage side effects, use of concomitant targeted therapies, and increased frequency of hospitalizations, healthcare provider visits, and monitoring tests. On switching from HT to CT, there was a doubling of the proportion of patients on sick leaves in both cohorts A and B. Conclusions: These results suggest an increased direct cost of care for CT relative to HT in European postmenopausal women with HR+, HER2– ABC. Furthermore, CT-based therapy appears to be associated with lower productivity of working-age patients, potentially increasing overall indirect costs.

Re-biopsy in breast cancer recurrence: Is there really a clinical impact?

e11549

Background: Several retrospective studies and 3 prospective studies have shown discordance in receptor status between primary tumor and metastasis leading to a treatment modification in about one out of 7 patients. However, some clinicians report unpublished data suggesting that these findings are not observed in all centers. We did prospectively a biopsy at suspicion of first relapse in our center and evaluated the impact of this biopsy on the management of our patients. Methods: Thirty four patients underwent a biopsy between October 2011 and January 2013. Hormonal receptor status was determined by the same IHC methodology for primary and metastatic tissue. Primary tumors were reanalyzed if necessary with our current IHC technique. A change in ER or PgR status was considered clinically significant if quantitative staining changed from <5 % to at least 10% of tumor cells expressing the hormonal receptor or if the opposite is observed. We tested HER2 status by IHC and/or FISH: HER2 3+ or 2+ and FISH positive cases were considered as HER2 positive. Results: Three of 34 patients were considered as screening failure. 1/31 (3.2 %) biopsies showed a benign disease, 2/31 (6.4 %) were non contributive and 5/31 (16 %) showed a metastasis of a second primary tumor. Two of these findings were totally unexpected according to clinical data. Changes in hormone receptor status were observed in 25 % but no change in HER2 status was observed. Time to recurrence was not significantly different between groups with or without modified hormonal status. No clinically significant complication was observed following the biopsies. Only patients presenting a second primary tumor had their management changed based on the new biopsy. Conclusions: We found discordance in hormone receptor status (25 %) but it did not change the treatment. Our study confirms the importance of re-biopsy in order to exclude benign disease or to find metastasis from an unknown and sometimes unexpected second primary tumor. Although our study does neither confirm changes in hormonal receptors resulting in the modification of the treatment strategy nor a change in HER2 status, our data suggest that a new biopsy at first relapse should be performed because unexpected second primaries can be discovered.

BOLERO-6: Phase II study of everolimus plus exemestane versus everolimus or capecitabine monotherapy in HR+, HER2- advanced breast cancer

TPS660

Background: Everolimus (EVE), an orally bioavailable inhibitor of the mammalian target of rapamycin (mTOR), has shown clinical activity as monotherapy and in combination with endocrine therapy (ET) in hormone-receptor–positive (HR+; estrogen and/or progesterone receptors) advanced breast cancer (ABC). In a pivotal phase 3 trial in patients with HR+ ABC progressing on ET, EVE + exemestane (EXE) significantly prolonged median progression-free survival (PFS) vs EXE alone per local (7.8 vs 3.2 months; log-rank P<.0001) or central (11.0 months for EVE+EXE vs 4.1 months for EXE alone; log-rank P<.0001) assessment. Capecitabine, an orally administered fluoropyrimidine carbamate indicated as monotherapy in paclitaxel and/or anthracycline-refractory ABC, has shown clinical benefit in patients with HR+, human epidermal growth factor receptor 2-negative (HER2-) ABC. The BOLERO-6 study in patients with HR+, HER2- ABC progressing on prior anastrozole or letrozole will compare PFS following EVE+EXE combination therapy vs EVE or capecitabine monotherapy. Methods: In this multicenter, open-label, randomized, 3-arm, phase 2 study, 300 patients will be randomized to receive either EVE (10 mg/d) + EXE (25 mg/d) combination therapy, or EVE (10 mg/d) alone, or capecitabine (1,250 mg/m2twice daily for 14 d/3-wk cycle) alone, until disease progression. Patients will be stratified based on the presence of visceral disease. Key eligibility criteria include age ≥18 years, postmenopausal status; histologic or cytologic confirmation of estrogen-receptor–positive, HER2- ABC; radiologic or objective evidence of recurrence or progression on prior aromatase inhibitors; Eastern Cooperative Oncology Group (ECOG) performance status ≤2. The primary endpoint is PFS with EVE+EXE vs EVE, based on local radiologic assessment (Response Evaluation Criteria in Solid Tumors [RECIST] 1.1). The key secondary endpoint is PFS with EVE+EXE vs capecitabine. Other secondary endpoints include overall survival, objective response rate, clinical benefit rate, safety, quality of life, and patient satisfaction with treatment. Enrollment will start in Q1 2013. Estimated study completion in Q1 2015. Clinical trial information: NCT01783444.