Excess body weight and postmenopausal breast cancer: Emerging molecular mechanisms and perspectives

Postmenopausal, obese women have a significantly higher risk of developing estrogen receptor-positive (ER+) breast tumors, that are resistant to therapies and are associated with higher recurrence and death rates. The global prevalence of overweight/obese women has reached alarming proportions and with postmenopausal ER+ breast carcinoma (BC) having the highest incidence among the three obesity-related cancers in females (i.e., breast, endometrial and ovarian), this is of significant concern. Elucidation of the precise molecular mechanisms underlying the pro-cancerous action of obesity in ER+BC is therefore critical for disease prevention and novel treatment initiatives. Interestingly, accumulating data has shown opposing relationships between obesity and cancer in either pre- or post-menopausal women. Excess body weight is associated with an increased risk of breast cancer in postmenopausal women and a decreased risk in pre-menopausal women. Moreover, excess adiposity during early life appears to be protective against postmenopausal breast cancer, including both ER+ and ER negative BC subtypes. Overall, estrogen-dependent mechanisms have been implicated as the main driving force in obesity-related breast tumorigenesis. In the present review we discuss the epidemiologic and mechanistic aspects of association between obesity and breast tumors after menopause, mainly in the context of hormone dependency. Molecular and cellular events underlying this association present as potential avenues for both therapeutic intervention as well as the prevention of BC-promoting processes linked to excess adiposity, which is proving to be vital in an increasingly obese global population.

Abstract P3-05-59: ER+ HER2-negative mBRCA1/2 carriers breast cancer patients (n=81): Clinical outcomes and molecular characterization via the 21-gene Breast Recurrence Score (RS) test vs the general RS-tested population (799,986 samples)

Background: The RS assay is a validated prognosticator/predictor of chemotherapy (CT) benefit in ER+ HER2-negative early-stage breast cancer (BC). It is offered to pts irrespective of BRCA1/2 status. We compared RS results, single-gene expression and gene group scores, between pts with germline BRCA1/2 mutations and the general BC pt population undergoing RS testing. Treatments/outcomes in the mBRCA1/2 cohort were also examined.

Methods: This real-life retrospective cohort study included consecutive ER+ HER2-negative mBRCA1/2 female carriers BC pts who had RS testing in 2004-2015. RS and gene expression data were compared to a previously described commercial use database (DB) (J Surg Oncol. 2020;122:611). Chi-square test and 1-sample t-test were used to compare RS distribution and single gene/gene group scores, respectively, between the cohort and the DB. Independent sample t-test was used to compare gene expression/gene group scores across pt subgroups within the mBRCA1/2 cohort. Fisher’s test/logistic regression were used to identify variables associated with distant recurrence in the mBRCA1/2 cohort.

Results: The analysis included 81 pts in the mBRCA1/2 cohort and 799,986 BC samples in the DB. Age at diagnosis was younger in the mBRCA1/2 pts vs the DB (median [IQR], 56 [47-61.5] vs 60 [51-67] yrs; P<.001). In mBRCA1 and mBRCA2 pts (32 and 48 pts, respectively; for 1 pt, the BRCA gene involved was unknown), RS distribution shifted towards the high RS category when compared to the DB (Table). Comparing single-gene expression and gene group scores in mBRCA1 pts vs the DB, revealed statistically significant differences in 12 of the 16 cancer genes in the RS assay, and in 2 gene group scores, all in a direction contributing to higher RS results. Similar analysis with mBRCA2 pts, revealed significant differences in expression of 10 genes and 3 gene group scores, all in a direction contributing to higher RS results. The only statistically significant difference in gene expression between the mBRCA1 and mBRCA2 pts was in the ESR (higher in mBRCA2 pts; P=.0407) and MYBL2 gene (higher in mBRCA1 pts; P=.0365) (Table). Of the 32 mBRCA1 pts, 18 (56%) received CT (RS 0-25, 1/14 [7%]; RS 26-100, 17/18 [94%]; treatment information was unavailable for 1 pt). Of the 48 mBRCA2 pts, 19 (40%) received CT (RS 0-25, 5/27 [19%]; RS 26-100, 14/21 [67%]). With a median (IQR) follow up of 8.2 (5.6-9.7) yrs from diagnosis, 9 pts had distant recurrence (1 mBRCA1 pt, 8 mBRCA2 pts). Their median RS result was 25 (range, 16-41), and 4 received adjuvant CT. No statistically significant differences were observed between these 9 pts and the 72 non-recurring pts in terms of pt/disease characteristics and CT treatment. A trend towards significance was observed with respect to the BRCA gene involved (recurrence rate of 3.1% in mBRCA1 pts vs 16.7% in mBRCA2 pts, P=.078). A statistically significant association was found between the proliferation and invasion gene group scores and the odds of having distant recurrence (proliferation group score: odds ratio [OR], 23.60 [95% CI, 1.4-397], P=.0281; invasion group score: OR, 5.1 [95% CI, 1.1-23], P=.0339). The ER and HER2 gene groups scores were not associated with distant recurrence.

Conclusions: Both mBRCA1 and mBRCA2 carriers are characterized by higher RS results that stem from a distinct gene expression profile of most genes in the RS assay.

Single Gene Expression and Gene Group Scores vs the Commercial Use DB

Citation Format: Rinat Yerushalmi, Adi Pomerantz, Ron Lewin, Shani Paluch-Shimon, Lior Soussan-Gutman, Frederick Baehner, Hillary Voet, Avital Bareket-Samish, Inbal Kedar, Yael Goldberg, Tamar Peretz-Yablonski, Luna Kadouri. ER+ HER2-negative mBRCA1/2 carriers breast cancer patients (n=81): Clinical outcomes and molecular characterization via the 21-gene Breast Recurrence Score (RS) test vs the general RS-tested population (799,986 samples) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-59.

A phase 1 study of intravenous mitazalimab, a CD40 agonistic monoclonal antibody, in patients with advanced solid tumors

Mitazalimab is an agonistic human monoclonal antibody targeting CD40, a target for anti-tumor immunotherapy. This phase 1, dose-escalation study evaluated the safety, dose-limiting toxicities (DLTs), pharmacokinetic and pharmacodynamic profile of mitazalimab. Adults with advanced solid malignancies received mitazalimab intravenously once every-2-weeks. Dose-escalation was pursued with and without pre-infusion corticosteroids for mitigation of infusion-related reactions (IRRs). In all, 95 patients were enrolled in 7 cohorts (n = 50, 75-2000 µg/kg) with corticosteroids and in 5 cohorts (n = 45, 75-1200 µg/kg) without corticosteroids. Two patients experienced DLTs (transient Grade-3 headache; Grade-3 drug-induced liver injury [Hy's law]). The most frequently reported (≥ 25%) treatment-emergent adverse events were fatigue (44.2%), pyrexia (38.9%), pruritus (38.9%), chills (27.4%), and headache (26.3%). IRRs were reported in 51.6% of patients; pruritus (30.5%; with corticosteroids [36.0%], without corticosteroids [24.4%]) was the most frequent. Following the first infusions of 600 μg/kg and 2000 μg/kg, mitazalimab was rapidly cleared from the systemic circulation with mean terminal half-life of 11.9 and 24.1 h, respectively. Pharmacokinetics appeared to exhibit target-mediated drug disposition at the tested doses. Mitazalimab treatment induced higher levels of selected chemokines and transient reduction of B-cells, T-cells, and NK cells. One patient (renal cell carcinoma) displayed partial response lasting 5.6 months. Stable disease was reported by 35 (36.8%) patients, persisting for ≥ 6 months in 9 patients. Mitazalimab has a manageable safety profile with acceptable pharmacokinetic and pharmacodynamic properties. Future clinical development will evaluate combination with existing treatment options. Trial registration NCT02829099 (ClinicalTrials.gov; July 7, 2016).

Abstract PD5-06: Safety of assisted reproductive technologies (ART) following treatment completion in young women with germline BRCA pathogenic variants having a pregnancy after breast cancer

BACKGROUND: Young breast cancer (BC) survivors are at risk of infertility. Ovarian stimulation for fertility preservation before (neo)adjuvant chemotherapy is standard of care. Research efforts have shown no negative prognostic effect of pregnancy following BC therapy, also among BRCA carriers. Currently, poor evidence is available on the safety to undergo ART following BC treatment, with no data in carriers of germline BRCA pathogenic variants. To provide evidence on the safety of fertility treatments in this specific population, we assessed the outcomes of a cohort of BRCA-mutated BC survivors who had a pregnancy after prior BC history by comparing the group of patients who underwent ART to achieve pregnancy to the group with spontaneous pregnancy. METHODS: We conducted a multicenter retrospective cohort study across 30 centers worldwide including women diagnosed at ≤ 40 years with stage I-III BC, between January 2000 and December 2012, bearing germline BRCA1/2 pathogenic variants. Survivors with a pregnancy (any outcome) after BC, with no disease-free survival (DFS) event before pregnancy, were assigned to the ART and non-ART group if their pregnancy was achieved through ART or spontaneously, respectively. ART procedures included ovulation induction, ovarian stimulation for in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI), and embryo transfer under hormonal replacement therapy (HRT). RESULTS: Of 1,424 patients registered in the study, 168 with a pregnancy after BC were included in the present analysis. A total of 22 patients were included in the ART group and 146 in the non-ART group. Before BC diagnosis, 18.2% patients in the ART group had at least one child, compared to 38.4% in the non-ART group (P=0.030). Patients had a median age at BC diagnosis of 33.0 vs 30.2 years old in the ART group and in the non-ART group, respectively (P=0.004); 45.4% and 17.1% had grade 1-2 tumors, respectively (P=0.008), and 59.1% vs 31.5% had hormone receptor-positive tumors, respectively (P=0.016). Both cohorts had similar tumor size and nodal stage characteristics. Type and duration of endocrine therapy were comparable between groups. The type of ART was not specified in 5 survivors (22.7%). Ovulation induction was used in 1 patient (4.5%), ovarian stimulation in 7 patients (31.8%), embryo transfer under HRT following oocyte donation in 5 patients (22.7%), and embryo transfer under HRT following oocyte and/or embryo cryopreservation for fertility preservation in 4 patients (18.2%). Median age at conception among survivors was 39.7 years in the ART group versus 35.4 years in the non-ART group (P<0.001). Overall, no differences in obstetrical outcomes were observed between groups, although there were more delivery complications in the ART group vs the non-ART group (22.1% vs 4.1%, respectively, P=0.011). Median follow-up from pregnancy was 3.4 years (range: 0.8-8.6) for patients in the ART group vs 5.0 years (range: 0.8-17.6) in the non-ART group (P=0.009). In the ART group, 2 patients (9.1%) experienced a DFS event (both were loco-regional recurrences) as compared to 40 patients (27.4%) in the non-ART group (P=0.182). No patients died in the ART group compared to 10 patients (6.9%) in the non-ART group. CONCLUSIONS: To our knowledge, this is the first study assessing the safety of ART in BC survivors bearing germline BRCA pathogenic variants. Even though the exposed cohort was small, results showed that the use of ART does not appear to increase the relapse risk at short-term follow-up. Further reproductive studies in BRCA-mutated BC patients are warranted.

Citation Format: Margherita Condorelli, Marco Bruzzone, Marcello Ceppi, Alberta Ferrari, Albert Grinshpun, Anne-Sophie Hamy, Evandro de Azambuja, Estela Carrasco, Fedro A. Peccatori, Antonio Di Meglio, Shani Paluch-Shimon, Philip D. Poorvu, Marta Venturelli, Christine Rousset-Jablonski, Claire Senechal, Luca Livraghi, Riccardo Ponzone, Laura De Marchis, Katarzyna Pogoda, Amir Sonnenblick, Cynthia Villarreal-Garza, Octavi Córdoba, Luis Teixeira, Florian Clatot, Kevin Punie, Rossella Graffeo Galbiati, Maria Vittoria Dieci, Alejandro Pérez-Fidalgo, Francois P. Duhoux, Fabio Puglisi, Arlindo R. Ferreira, Eva Blondeaux, Tamar Peretz-Yablonski, Olivier Caron, Claire Saule, Lieveke Ameye, Judith Balmaña, Ann H. Partridge, Hatem A. Azim, Jr, Isabelle Demeestere, Matteo Lambertini. Safety of assisted reproductive technologies (ART) following treatment completion in young women with germline BRCA pathogenic variants having a pregnancy after breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD5-06.

Safety of assisted reproductive techniques in young women harboring germline pathogenic variants in BRCA1/2 with a pregnancy after prior history of breast cancer

BACKGROUND

Knowledge is growing on the safety of assisted reproductive techniques (ART) in cancer survivors. No data exist, however, for the specific population of breast cancer patients harboring germline BRCA1/2 pathogenic variants.

PATIENTS AND METHODS

This is a multicenter retrospective cohort study across 30 centers worldwide including women diagnosed at ≤40 years with stage I-III breast cancer, between January 2000 and December 2012, harboring known germline BRCA1/2 pathogenic variants. Patients included in this analysis had a post-treatment pregnancy either achieved through use of ART (ART group) or naturally (non-ART group). ART procedures included ovulation induction, ovarian stimulation for in vitro fertilization or intracytoplasmic sperm injection, and embryo transfer under hormonal replacement therapy.

RESULTS

Among the 1424 patients registered in the study, 168 were eligible for inclusion in the present analysis, of whom 22 were in the ART group and 146 in the non-ART group. Survivors in the ART group conceived at an older age compared with those in the non-ART group (median age: 39.7 versus 35.4 years, respectively). Women in the ART group experienced more delivery complications compared with those in the non-ART group (22.1% versus 4.1%, respectively). No other apparent differences in obstetrical outcomes were observed between cohorts. The median follow-up from pregnancy was 3.4 years (range: 0.8-8.6 years) in the ART group and 5.0 years (range: 0.8-17.6 years) in the non-ART group. Two patients (9.1%) in the ART group experienced a disease-free survival event (specifically, a locoregional recurrence) compared with 40 patients (27.4%) in the non-ART group. In the ART group, no patients deceased compared with 10 patients (6.9%) in the non-ART group.

CONCLUSION

This study provides encouraging safety data on the use of ART in breast cancer survivors harboring germline pathogenic variants in BRCA1/2, when natural conception fails or when they opt for ART in order to carry out preimplantation genetic testing.

Final results from the PERUSE study of first-line pertuzumab plus trastuzumab plus a taxane for HER2-positive locally recurrent or metastatic breast cancer, with a multivariable approach to guide prognostication

BACKGROUND

The phase III CLinical Evaluation Of Pertuzumab And TRAstuzumab (CLEOPATRA) trial established the combination of pertuzumab, trastuzumab and docetaxel as standard first-line therapy for human epidermal growth factor receptor 2 (HER2)-positive locally recurrent/metastatic breast cancer (LR/mBC). The multicentre single-arm PERtUzumab global SafEty (PERUSE) study assessed the safety and efficacy of pertuzumab and trastuzumab combined with investigator-selected taxane in this setting.

PATIENTS AND METHODS

Eligible patients with inoperable HER2-positive LR/mBC and no prior systemic therapy for LR/mBC (except endocrine therapy) received docetaxel, paclitaxel or nab-paclitaxel with trastuzumab and pertuzumab until disease progression or unacceptable toxicity. The primary endpoint was safety. Secondary endpoints included progression-free survival (PFS) and overall survival (OS). Prespecified subgroup analyses included subgroups according to taxane, hormone receptor (HR) status and prior trastuzumab. Exploratory univariable analyses identified potential prognostic factors; those that remained significant in multivariable analysis were used to analyse PFS and OS in subgroups with all, some or none of these factors.

RESULTS

Of 1436 treated patients, 588 (41%) initially received paclitaxel and 918 (64%) had HR-positive disease. The most common grade ≥3 adverse events were neutropenia (10%, mainly with docetaxel) and diarrhoea (8%). At the final analysis (median follow-up: 5.7 years), median PFS was 20.7 [95% confidence interval (CI) 18.9-23.1] months overall and was similar irrespective of HR status or taxane. Median OS was 65.3 (95% CI 60.9-70.9) months overall. OS was similar regardless of taxane backbone but was more favourable in patients with HR-positive than HR-negative LR/mBC. In exploratory analyses, trastuzumab-pretreated patients with visceral disease had the shortest median PFS (13.1 months) and OS (46.3 months).

CONCLUSIONS

Mature results from PERUSE show a safety and efficacy profile consistent with results from CLEOPATRA and median OS exceeding 5 years. Results suggest that paclitaxel is a valid alternative to docetaxel as backbone chemotherapy. Exploratory analyses suggest risk factors that could guide future trial design.

Preliminary safety and efficacy of first-line pertuzumab combined with trastuzumab and taxane therapy for HER2-positive locally recurrent or metastatic breast cancer (PERUSE)

BACKGROUND

Pertuzumab combined with trastuzumab and docetaxel is the standard first-line therapy for HER2-positive metastatic breast cancer, based on results from the phase III CLEOPATRA trial. PERUSE was designed to assess the safety and efficacy of investigator-selected taxane with pertuzumab and trastuzumab in this setting.

PATIENTS AND METHODS

In the ongoing multicentre single-arm phase IIIb PERUSE study, patients with inoperable HER2-positive advanced breast cancer (locally recurrent/metastatic) (LR/MBC) and no prior systemic therapy for LR/MBC (except endocrine therapy) received docetaxel, paclitaxel or nab-paclitaxel with trastuzumab [8 mg/kg loading dose, then 6 mg/kg every 3 weeks (q3w)] and pertuzumab (840 mg loading dose, then 420 mg q3w) until disease progression or unacceptable toxicity. The primary end point was safety. Secondary end points included overall response rate (ORR) and progression-free survival (PFS).

RESULTS

Overall, 1436 patients received at least one treatment dose (initially docetaxel in 775 patients, paclitaxel in 589, nab-paclitaxel in 65; 7 discontinued before starting taxane). Median age was 54 years; 29% had received prior trastuzumab. Median treatment duration was 16 months for pertuzumab and trastuzumab and 4 months for taxane. Compared with docetaxel-containing therapy, paclitaxel-containing therapy was associated with more neuropathy (all-grade peripheral neuropathy 31% versus 16%) but less febrile neutropenia (1% versus 11%) and mucositis (14% versus 25%). At this preliminary analysis (52 months' median follow-up), median PFS was 20.6 [95% confidence interval (CI) 18.9-22.7] months overall (19.6, 23.0 and 18.1 months with docetaxel, paclitaxel and nab-paclitaxel, respectively). ORR was 80% (95% CI 78%-82%) overall (docetaxel 79%, paclitaxel 83%, nab-paclitaxel 77%).

CONCLUSIONS

Preliminary findings from PERUSE suggest that the safety and efficacy of first-line pertuzumab, trastuzumab and taxane for HER2-positive LR/MBC are consistent with results from CLEOPATRA. Paclitaxel appears to be a valid alternative taxane backbone to docetaxel, offering similar PFS and ORR with a predictable safety profile.

CLINICALTRIALS.GOV

NCT01572038.

Abstract P4-21-04: Preliminary safety and efficacy of first-line pertuzumab combined with trastuzumab and taxane therapy for HER2-positive locally recurrent/metastatic breast cancer (PERUSE)

Background: First-line (1L) docetaxel+trastuzumab+pertuzumab (THP) for HER2-positive metastatic breast cancer (MBC) significantly improved progression-free survival (PFS) and overall survival in the phase III CLEOPATRA trial, and led to the approval of this regimen. PERUSE (NCT01572038) was designed to assess the safety and efficacy of investigator's choice of taxane+HP for 1L locally recurrent (LR)/MBC, and allows exploration of safety and efficacy in a larger population.

Methods:

PERUSE is a multicenter, single-arm phase IIIb study. Patients (pts) with Eastern Cooperative Oncology Group performance status ≤2 and no prior systemic therapy for LR/MBC (except endocrine therapy) receive T, paclitaxel (PAC), or nab-PAC plus H (8 mg/kg→6 mg/kg every 3 weeks [q3w]) and P (840 mg→420 mg q3w) until disease progression (PD) or unacceptable toxicity. The primary endpoint is safety. Secondary endpoints include best overall response (BOR) and PFS.

Results:

The safety/ITT population includes 1436 pts at data cutoff (1 Apr 2016). Median follow-up was 17.2 mo (range, <1–41.4). The median pt age was 54 years (range 23–87), 64% had hormone receptor-positive disease, 27% received adjuvant H, and 75% had visceral disease. Pts received T, PAC, nab-PAC, H, and P for a median of 3.8 mo (range <1–24.2; n=791), 4.2 mo (<1–36.6; n=618), 3.9 mo (<1–17.3; n=73), 16.0 mo (<1–45.9; n=1435), and 16.1 mo (<1–45.9; n=1436), respectively.

Most pts discontinued taxanes for 'other' reasons (25%), adverse events (AEs; 16%), PD, or investigator decision (15% each); H, for PD or AEs (46% and 7%); and P, for PD or AEs (46% and 8%).

Grade ≥3 treatment-emergent AEs (TEAEs) of interest are shown in table 1. Serious TEAEs were reported in 282 (36%) pts on T, 185 (31%) on PAC, and 21 (32%) on nab-PAC. Preliminary efficacy by taxane is shown in table 2.

Table 1Pts, n (%)TPACNab-PAC n=775n=589n=65Neutropenia110 (14)31 (5)1 (2)Diarrhea62 (8)50 (8)4 (6)Febrile neutropenia81 (10)7 (1)0Fatigue21 (3)10 (2)1 (2)Asthenia16 (2)10 (2)0Peripheral neuropathy10 (1)15 (3)0Anemia11 (1)12 (2)2 (3)Left ventricular dysfunction1 (<1)9 (2)1 (2)

Table 2 TPACNab-PACBOR, based on pts with measureable disease at baseline, n (%)n=659n=482n=53Complete72 (11)80 (17)4 (8)Partial442 (67)319 (66)38 (72)Stable disease112 (17)62 (13)8 (15)PD18 (3)12 (2)2 (4)Missing15 (2)9 (2)1 (2)PFS, ITT populationn=775n=589n=65Pts with events, n (%)439 (57)324 (55)40 (62)Median, mo (95% confidence interval)19.6 (17.4–22.6)24.8 (20.7–27.0)18.1 (11.9–34.2)25th–75th percentile, mo9.4–not reached (NR)10.2–NR7.9–NR

Conclusion:

The preliminary findings of this large, single-arm study suggest that safety and efficacy of 1L taxane+HP for HER2-positive LR/MBC are in keeping with the results of the phase III CLEOPATRA study. There was less febrile neutropenia with PAC/nab-PAC+HP compared with THP, and preliminary PFS was similar to that seen in the CLEOPATRA study for all taxane+HP combinations.

Citation Format: Bachelot T, Puglisi F, Ciruelos E, Peretz-Yablonski T, Schneeweiss A, Easton V, Lindegger N, Restuccia E, Miles D. Preliminary safety and efficacy of first-line pertuzumab combined with trastuzumab and taxane therapy for HER2-positive locally recurrent/metastatic breast cancer (PERUSE) [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 P4-21-04.

Abstract OT1-1-02: A single-arm phase IIIb study of pertuzumab and trastuzumab with a taxane as first-line therapy for patients with HER2-positive advanced breast cancer (PERUSE)

Background: Pertuzumab (P), a humanized monoclonal antibody, inhibits signaling downstream of HER2 by binding to the dimerization domain of the receptor and preventing heterodimerization with other HER family members. The epitope recognized by P is distinct from that bound by trastuzumab (H) and so their complementary mechanisms of action result in a more comprehensive HER2 blockade. Data from the phase III trial CLEOPATRA showed significantly improved PFS in patients (pts) receiving P + H + docetaxel compared with H + docetaxel + placebo as first-line treatment for HER2-positive metastatic breast cancer (BC).

Trial design: PERUSE is a phase IIIb, multicenter, open-label, single-arm study in pts with HER2-positive metastatic or locally recurrent BC who have not been treated with systemic nonhormonal anticancer therapy for metastatic cancer. Pts will receive, P: 840 mg initial dose, 420 mg q3w IV; H: 8 mg/kg initial dose, 6 mg/kg q3w IV; taxane: docetaxel, paclitaxel, or nab-paclitaxel according to local guidelines. Treatment will be administered until disease progression or unacceptable toxicity. A planned protocol amendment will allow hormone receptor-positive pts to receive endocrine therapy alongside P+H after completion of taxane therapy, in line with clinical practice.

Eligibility criteria: At baseline, pts must have an LVEF of ≥50%, an ECOG PS of 0, 1, or 2, a disease-free interval of ≥6 months, and must not have received prior anti-HER2 agents for the treatment of metastatic BC. Prior H and/or lapatinib in the (neo)adjuvant setting is permitted, providing there was no disease progression during treatment. Pts must not have experienced other malignancies within the last 5 yrs other than carcinoma in situ of the cervix or basal cell carcinoma. There must be no clinical or radiographic evidence of CNS metastases or clinically significant cardiovascular disease.

Specific aims: As H was not widely available in the (neo)adjuvant setting prior to CLEOPATRA recruitment, a relatively low proportion of pts in CLEOPATRA had previously received H. PERUSE will assess the safety and tolerability of P+H + choice of taxane as first-line therapy for pts with HER2-positive metastatic or locally advanced BC in a pt population likely to have experienced wider exposure to prior H therapy.

Statistical methods: The primary endpoints of the PERUSE study are safety and tolerability. Secondary endpoints include PFS, OS, ORR, CBR, duration of response, time to response and QoL. The final analysis will be performed when 1500 pts have been followed up for at least 12 months after the last pt receives last study treatment unless they have been lost to follow-up, withdrawn consent, or died, or if the study is prematurely terminated by the sponsor. Safety analyses are planned after enrollment of ∼350, 700, and 1000 pts. Additionally, a data and safety monitoring board will review safety data after ∼50 pts have been enrolled and then every 6 months.

Current and target accrual: Enrollment of the first pt is expected in June 2012 with a total of 1500 pts planned to be recruited.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr OT1-1-02.