Pooled ctDNA analysis of MONALEESA phase III advanced breast cancer trials

BACKGROUND

The phase III MONALEESA trials tested the efficacy and safety of the cyclin-dependent kinase (CDK)4/6 inhibitor ribociclib with different endocrine therapy partners as first- or second-line treatment of hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer (ABC). Using the largest pooled biomarker dataset of the CDK4/6 inhibitor ribociclib in ABC to date, we identified potential biomarkers of response to ribociclib.

PATIENTS AND METHODS

Baseline circulating tumour DNA from patients in the MONALEESA trials was assessed using next-generation sequencing. An analysis of correlation between gene alteration status and progression-free survival (PFS) was carried out to identify potential biomarkers of response to ribociclib.

RESULTS

Multiple frequently altered genes were identified. Alterations in ERBB2, FAT3, FRS2, MDM2, SFRP1, and ZNF217 were associated with a greater PFS benefit with ribociclib versus placebo. Patients with high tumour mutational burden (TMB) and with ANO1, CDKN2A/2B/2C, and RB1 alterations exhibited decreased sensitivity to ribociclib versus placebo.

CONCLUSIONS

Although exploratory, these results provide insight into alterations associated with the improved response to ribociclib treatment and may inform treatment sequencing in patients with actionable alterations following progression on CDK4/6 inhibitors. Validation of potential biomarkers identified here and development of prospective trials testing their clinical utility are warranted.

CLINICALTRIALS

GOV IDENTIFIERS

NCT01958021, NCT02422615, NCT02278120.

Prognostic gene expression signature for high-grade serous ovarian cancer

BACKGROUND

Median overall survival (OS) for women with high-grade serous ovarian cancer (HGSOC) is ∼4 years, yet survival varies widely between patients. There are no well-established, gene expression signatures associated with prognosis. The aim of this study was to develop a robust prognostic signature for OS in patients with HGSOC.

PATIENTS AND METHODS

Expression of 513 genes, selected from a meta-analysis of 1455 tumours and other candidates, was measured using NanoString technology from formalin-fixed paraffin-embedded tumour tissue collected from 3769 women with HGSOC from multiple studies. Elastic net regularization for survival analysis was applied to develop a prognostic model for 5-year OS, trained on 2702 tumours from 15 studies and evaluated on an independent set of 1067 tumours from six studies.

RESULTS

Expression levels of 276 genes were associated with OS (false discovery rate < 0.05) in covariate-adjusted single-gene analyses. The top five genes were TAP1, ZFHX4, CXCL9, FBN1 and PTGER3 (P < 0.001). The best performing prognostic signature included 101 genes enriched in pathways with treatment implications. Each gain of one standard deviation in the gene expression score conferred a greater than twofold increase in risk of death [hazard ratio (HR) 2.35, 95% confidence interval (CI) 2.02-2.71; P < 0.001]. Median survival [HR (95% CI)] by gene expression score quintile was 9.5 (8.3 to -), 5.4 (4.6-7.0), 3.8 (3.3-4.6), 3.2 (2.9-3.7) and 2.3 (2.1-2.6) years.

CONCLUSION

The OTTA-SPOT (Ovarian Tumor Tissue Analysis consortium - Stratified Prognosis of Ovarian Tumours) gene expression signature may improve risk stratification in clinical trials by identifying patients who are least likely to achieve 5-year survival. The identified novel genes associated with the outcome may also yield opportunities for the development of targeted therapeutic approaches.

Abstract PD2-10: Treatment with abemaciclib modulates the immune response in gene expression analysis of the neoMONARCH neoadjuvant study of abemaciclib in postmenopausal women with HR+, HER2 negative breast cancer

Background: Abemaciclib is a selective inhibitor of CDK4 & 6 approved on a continuous dosing schedule for the treatment of HR+, HER2- metastatic breast cancer (MBC) patients (pts) in combination with endocrine therapy or as monotherapy. Recent studies have demonstrated the potential for CDK4 & 6 inhibitors, including abemaciclib, to promote anti-tumor immunity. Schaer et al., (Cell Reports 2018) showed that abemaciclib monotherapy results in upregulation of antigen presentation on tumor cells and increases T-cell activation. These activities synergized with anti-PD-L1 therapy to further enhance immune activation leading to complete tumor rejection in murine tumor models (Schaer et al., Cell Reports 2018). In this exploratory analysis, we evaluated the early and late immune-modulating effects of abemaciclib in the neoadjuvant study neoMONARCH (NCT02441946).

Methods: NeoMONARCH is a Phase II trial in women with stage I-IIIB HR+, HER2- BC evaluating neoadjuvant treatment with 2 weeks of abemaciclib, alone or in combination with anastrozole (abemaciclib+ANZ), or ANZ alone. All patients received 14 weeks of abemaciclib +ANZ after the first 2 weeks of treatment. Serial biopsies were collected at 3 time points: Baseline (BL) - prior to treatment, Early - after 2 weeks of therapy with abemaciclib, ANZ, or abemaciclib+ANZ, and Late – after 2 weeks of initial therapy followed by 14 weeks of abemaciclib+ANZ. RNA was extracted from formalin fixed paraffin embedded (FFPE) tumor biopsies at each time point and subjected to whole transcriptome RNA sequencing. The curated data were subjected to statistical analysis using ANOVA tests followed by pathway analysis using Ingenuity Pathway Analysis (IPA) and Gene Set Enrichment Analysis (GSEA).

Results: Consistent with the known activity of abemaciclib to inhibit the cell cycle, we observed at the early and late time points a significant treatment induced downregulation of genes related to mitotic spindle organization, replication stress response, G2M checkpoint, and E2F targets. Abemaciclib treatment for 2 weeks, alone or in combination with ANZ, followed by 14 weeks of combination therapy was associated with upregulation of gene expression signatures related to T-cell immune response and antigen presentation. Importantly, this phenomenon was notobserved with 2 weeks of ANZ treatment alone followed by 14 weeks of combination therapy.

Conclusion: These data lend support that continuous inhibition of CDK4 & 6 signaling by abemaciclib treatment leads to prolonged cell cycle arrest resulting in tumor cell apoptosis & senescence, which then leads to an enhanced immune activation.

Citation Format: Hurvitz S, Martin M, Press M, Wijayawardana S, Brahmachary M, Ebert PJ, Young S, Jansen V, Slamon D. Treatment with abemaciclib modulates the immune response in gene expression analysis of the neoMONARCH neoadjuvant study of abemaciclib in postmenopausal women with HR+, HER2 negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD2-10.

Abstract P3-10-08: Markers of response to CDK4 & 6 inhibition from neoMONARCH: A phase II neoadjuvant study of abemaciclib in postmenopausal women with hormone receptor positive, HER2 negative breast cancer

Background: Combination treatments of endocrine therapy (ET) with CDK4 & 6 inhibitors have improved outcomes in patients with HR+ advanced breast cancer, both as initial therapy and after progression on ET. Abemaciclib is a selective inhibitor of CDK4 & 6 approved on a continuous dosing schedule for the treatment of HR+, HER2- MBC patients (pts), alone or in combination with ET. However, biomarkers that predict benefit from this class of agents remain elusive. We previously reported in the phase II neoadjuvant neoMONARCH study (NCT02441946), after 2 weeks of treatment, abemaciclib, alone or in combination with anastrozole (ANZ), led to a significantly higher rate of complete cell cycle arrest (CCCA, defined as Ki67 ≤2.7%) compared to ANZ alone in early stage HR+, HER2- breast cancer (Martin et al. SABCS 2017). As an exploratory aim of this trial, we evaluated the gene expression analyses in order to determine markers of sensitivity and resistance to therapy.

Methods: Serial biopsies were collected at 3 time points: Baseline (BL) - prior to treatment, Early – after 2 weeks of therapy with abemaciclib, ANZ, or abemaciclib+ANZ, and Late – after 2 weeks of initial therapy followed by 14 weeks of abemaciclib+ANZ. RNA was extracted from FFPE tumor biopsies at each timepoint and subjected to a Cell Cycle Associated Gene (CCAG) expression panel using the Modaplex® platform and whole transcriptome RNA sequencing. Ki67 was measured at each time point by immunohistochemistry (IHC). Tumors were categorized by the post-treatment Ki67 expression as either sensitive (Ki67 ≤2.7) or resistant (Ki67 ≥7.4), based upon the IMPACT and POETIC studies. Additionally, tumors intrinsically resistant/sensitive to therapy were also identified.

Results: ANZ-treated tumors that did not achieve CCCA at 2 weeks (N= 8) displayed higher expression of the cell cycle associated genes FOXM1, E2F1, TOPO2A, and RRM2. The addition of abemaciclib to ANZ decreased gene expression in a majority of the tumors (N=5, 62.5%). Tumors intrinsically resistant to treatment with abemaciclib+ANZ displayed persistently elevated levels of cell cycle associated genes compared to sensitive tumors. Finally, gene expression signature of Rb loss-of-function (Rbsig) and RB1 gene expression levels were associated with sensitivity to abemaciclib.

Conclusion: On-treatment Ki67 indicated treatment sensitivity and correlated with cell cycle associated gene expression in sensitive and resistant tumors. These exploratory analyses suggest that gene expression analyses may identify genomic markers for abemaciclib and ET treatment sensitivity and may help inform in which tumors to use abemaciclib.

Citation Format: Hurvitz S, Martin M, Wijayawardana S, Brahmachary M, Ebert PJ, Young S, Jansen V, Slamon D. Markers of response to CDK4 & 6 inhibition from neoMONARCH: A phase II neoadjuvant study of abemaciclib in postmenopausal women with hormone receptor positive, HER2 negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-10-08.

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

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

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

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

Abstract P4-03-15: Targeting Src kinase blocks development of afatinib resistance in HER2-positive breast cancer

Background: Afatinib is an irreversible pan-HER inhibitor approved for non-small cell lung cancer. We have previously shown that afatinib inhibits growth of HER2-positive breast cancer cells and enhances response to trastuzumab. However, we have also shown that long-term exposure to tyrosine kinase inhibitors leads to the development of acquired resistance. To determine if acquired afatinib resistance develops in HER2-positive breast cancer cells, we exposed a HER2-positive breast cancer cell line to afatinib for 6 months and investigated alterations in the cells following long-term exposure.

Methods: SKBR3 cells were treated with 150 nM afatinib twice-weekly for 6 months. Growth response to drug inhibitors was assessed by acid phosphatase assay. Drug sensitivity was examined in four HER2-positive cell lines (SKBR3, EFM192A, BT474 and HCC1954) and three acquired trastuzumab resistant cell lines (SKBR3-T, BT474-T and EFM192A-T). Reverse phase protein array (RPPA) was used to determine alterations in key signaling pathways. Src, p-Src, EGFR, p-EGFR, ERK1/2, p-ERK 1/2 levels were examined by Western blotting. To examine the prevention of the development of afatinib resistance, cells were treated twice weekly with afatinib, dasatinib, or the combination and stained with crystal violet when confluent.

Results: Following 6 months of afatinib treatment, the SKBR3-A cells were more resistant to afatinib compared to parental cells (IC50 SKBR3-A 284 ± 28.2 nM vs SKBR3-Par 10.9 ± 3.4 nM). Furthermore, the resistant cells were cross-resistant to lapatinib, neratinib and trastuzumab. RPPA interrogation of the SKBR3-A cells showed alterations in several pathways, including significantly increased levels of p-Src (Y416). SKBR3-A cells were more sensitive to Src inhibition with dasatinib compared to SKBR3-Par cells and the combination of afatinib and dasatinib was highly synergistic in SKBR3-A cells (CI value = 0.09 ± 0.06). The combination of afatinib and dasatinib was also synergistic in the trastuzumab resistant SKBR3-T cells (Table). Afatinib and dasatinib inhibited EGFR and Src activation and ERK 1/2 signalling in SKBR3-A cells.

Short-term resistance assays showed that the addition of dasatinib to afatinib blocks the emergence of resistant cells in three of four HER2 positive cell lines tested and two of the three acquired trastuzumab resistant cell lines tetsed.

Conclusion: HER2-positive breast cancer cells that are highly sensitive to afatinib can develop acquired resistance to afatinib within six months. Src is a potential target to prevent the development of afatinib resistance and thus combined treatment with afatinib and dasatinib may be beneficial in patients with HER2-positive breast cancer.

Percentage growth in HER2-positive cells treated with afatinib and/or dasatinib for 5 days. 20 nM Afatinib40 nM Dasatinib20 nM Afatinib + 40 nM DasatinibSKBR325.2 ± 6.1109.9 ± 6.222.6 ± 6.2SKBR3-A62.1 ± 0.787.3 ± 11.036.3 ± 0.3*SKBR3-T42.6 ± 4.9107.4 ± 9.729.3 ± 3.5*BT47418.2 ± 3.079.5 ± 5.213.3 ± 1.1BT474-T6.9 ± 2.795.3 ± 2.06.2 ± 2.3EFM192A39.1 ± 4.7105.7 ± 3.135.3 ± 2.7EFM192A-T30.4 ± 5.299.8 ± 2.528.5 ± 4.4HCC195461.8 ± 8.180.5 ± 8.219.4 ± 3.6** indicates enhanced anti-proliferative response for the combination compared to the single agents.

Citation Format: Conlon N, Canonici A, Morgan C, Cremona M, Hennessey BT, Eustace A, O'Brien N, Slamon D, Crown J, O'Donovan N. Targeting Src kinase blocks development of afatinib resistance in HER2-positive breast cancer [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 P4-03-15.

Abstract P4-22-03: Palbociclib in combination with endocrine therapy in treatment-naive and previously treated elderly women with HR+, HER2– advanced breast cancer: a pooled analysis from randomized phase 2 and 3 studies

Background: At least 40% of breast cancers are diagnosed in women ≥65 y old and most are hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-). Palbociclib (PAL) is an oral, small-molecule inhibitor of cyclin-dependent kinases 4 and 6. Randomized studies of PAL combined with endocrine therapy (ET) demonstrated significantly improved progression-free survival (PFS) in patients (pts) with treatment-naive and previously treated advanced breast cancer (ABC).

Methods: We evaluated the efficacy of PAL+ET vs ET alone in pts aged ≥65-74 and ≥75 y across multiple pivotal randomized phase 2 and 3 studies. Safety and pharmacokinetics (PK) data (blood samples collected from pts in phase 1/2 [PALOMA-1] and phase 1 studies [NCT00141297 and NCT00420056]) for PAL+ET were pooled and compared across age groups. Pts who had not received treatment for ABC were randomized to receive PAL+letrozole (LET) or LET alone/with placebo (PBO; PALOMA-1, open-label/PALOMA-2, double-blind). Pts who had progressed on prior ET were randomized to receive PAL+fulvestrant (FUL) or PBO+FUL (PALOMA-3, double-blind). The primary endpoint for these studies was investigator-assessed PFS. Safety assessments and blood counts occurred at baseline and every 2 weeks for the first 2 cycles and on day 1 of subsequent cycles.

Results: Among 872 pts treated with PAL+ET, 221 (25%) were aged ≥65-74 y and 83 (10%) were ≥75 y (PAL+LET: n=528, 162 and 56, respectively; PAL+FUL: n=347, 59 and 27). Median (range) treatment durations were 440 (1-1615) d, 502 (1-1615) d, and 459 (21-1404) d, respectively. Improvement in efficacy endpoints was seen with PAL+ET vs ET across all age groups (Table 1). Incidence of adverse events (AEs), serious AEs and discontinuations due to AEs were similar in the overall population (99%, 19%, 3%) and in pts aged ≥65-74 (99%, 25%, 5%) and ≥75 y (100%, 30%, 6%). Incidence of all grades and grade 3/4 neutropenia were also similar across age groups (overall: 67% and 54%; ≥65-74 y: 64% and 51%; ≥75 y: 77% and 60%). PK analysis showed no clinically relevant differences between arithmetic means, medians, and geometric means of the apparent oral clearance across age groups.

Conclusions: PAL in combination with ET is an effective and well-tolerated treatment option for elderly pts with HR+/HER2- endocrine-sensitive and -resistant ABC. A dose adjustment based on age is not required.

Sponsor: Pfizer

Table 1. PFS in pts ?65-74 and ?75 y (ITT populations)OverallAged ≥65-74 yAged ≥75 yPALOMA-1/PALOMA-2PAL+LET vs528 vs 303162 vs 9456 vs 26LET/LET+PBO,* nHR (95% CI);0.53 (0.44-0.64);0.66 (0.45-0.97);0.31 (0.16-0.61);1-sided P value&lt;0.00010.01620.0002Median PFS (95% CI), mo24.4 (22.0-26.2) vs27.5 (24.2-NR) vsNR (19.2-NR) vs13.6 (11.1-16.4)21.8 (16.3-31.3)10.9 (4.9-24.9)PALOMA-3PAL+FUL vs347 vs 17459 vs 3727 vs 6FUL+PBO, nHR (95% CI);0.46 (0.36-0.59);0.25 (0.14-0.45);0.87 (0.27-2.79);1-sided P value&lt;0.0001&lt;0.00010.4074Median PFS (95% CI), mo9.5 (9.2-11.0) vs16.1 (12.0-NR) vs13.6 (7.5-NR) vs4.6 (3.5-5.6)3.7 (1.9-5.3)7.4 (1.9-NR)HR=hazard ratio; ITT=intent to treat; NR=not reached. *Does not include 5 pts from phase 1 of PALOMA-1.

Citation Format: Rugo HS, Turner NC, Finn RS, Joy AA, Verma S, Harbeck N, Moulder S, Masuda N, Im Y-H, Zhang K, Kim S, Sun W, Schnell P, Huang-Bartlett C, Slamon D. Palbociclib in combination with endocrine therapy in treatment-naive and previously treated elderly women with HR+, HER2– advanced breast cancer: a pooled analysis from randomized phase 2 and 3 studies [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 P4-22-03.

Abstract P6-07-09: Biomarker analysis from the neoadjuvant KRISTINE study in HER2-positive early breast cancer (EBC)

Introduction KRISTINE (NCT02131064) is an open-label, phase 3 study of neoadjuvant trastuzumab emtansine + pertuzumab (T-DM1+P) vs docetaxel + carboplatin + trastuzumab + pertuzumab (TCH+P) in pts with HER2+ EBC (all pts, Table). In exploratory analyses we assessed whether HER2 expression and gene amplification levels and PIK3CA mutation were associated with pathologic complete response (pCR) in KRISTINE.

Methods Treatment-naive pts with stage II–IIIC HER2+ EBC were randomized to receive 6 cycles of T-DM1+P or TCH+P and assessed for the primary endpoint, pCR (ypT0/is, ypN0). HER2 status was confirmed centrally as immunohistochemistry (IHC) status of IHC3+ and/or HER2/CEP17 gene ratio ≥2 by in situ hybridization (ISH) before study entry. Baseline HER2 mRNA, PIK3CA mutation, and hormone receptor (HR) status were evaluated. Rates of pCR were compared across biomarker subgroups, including: HER2 mRNA, HER2 IHC staining percentage, HER2 gene ratio, and PIK3CA mutation. Incidence of overlap between biomarkers was assessed. All analyses were descriptive.

Results KRISTINE randomized 444 pts (data cutoff, Dec 3, 2015; TCH+P=221; T-DM1+P=223). The biomarker population was representative of the ITT population. Biomarker values and distribution were balanced across treatment arms. Lower pCR rates were seen in both treatment arms across biomarker subgroups with lower vs higher HER2 expression levels (Table). PIK3CA mutation was associated with numerically lower pCR with T-DM1+P but not TCH+P. Evaluation of 15 pts who progressed during T-DM1+P neoadjuvant therapy suggests that nonresponse to therapy in this arm may be associated with low HER2 levels (mRNA, IHC, and ISH).

PIK3CA mutation rate was higher in tumors with ≤median HER2 mRNA (38%) vs &gt;median (16%), and in focal (53%) and variable (41%) HER2 expression vs homogeneous (24%). A numerically higher proportion of HR positivity was seen in the HER2 IHC2+ (81%) subgroup vs IHC3+ (55%), and in the focal (83%) and variable (62%) HER2 subgroups vs homogeneous (53%).

Table TCH+PT-DM1+P  BiomarkernpCR (%)npCR (%)Difference in pCR rates (%)95% CIAll pts22155.722344.4-11.3-20.5, -2.0HER2      IHC3+19460.819549.7-11.1-20.9, -1.3IHC2+2520.0287.1-12.9-31.2, 5.5HER2 IHC 2+/3+ fraction*      Focal (&lt;30%)1533.3160-33.3-57.2, -9.5Variable (30–79%)2729.62722.2-7.4-30.7, 15.9Homogeneous (≥80%)17961.518051.7-9.8-20.0, 0.4HER2 mRNA expression      ≤median10649.110937.6-11.4-24.6, 1.7&gt;median10763.610851.9-11.7-24.8, 1.4HER2/CEP17 gene ratio      ≥2 to &lt;44533.35219.2-14.1-31.6, 3.4≥416662.015853.2-8.9-19.6, 1.8PIK3CA mutation      Mutated5354.76131.1-23.6-41.3, -5.8Nonmutated16056.315151.0-5.3-16.3, 5.8*Categorization based on sum of IHC2+ and IHC3+ staining percentage.

Conclusions None of the evaluated biomarker subgroups showed superior pCR rates for T-DM1+P vs TCH+P. Lower HER2 levels based on mRNA and protein expression and gene amplification were associated with numerically lower pCR in both treatment arms. PIK3CA mutation results differ from prior observations. Unfavorable biomarkers for pCR, like low HER2, PIK3CA mutation, and HR positivity, showed a tendency for co-expression, which should be considered when planning future trials in HER2+ BC.

Citation Format: de Haas SL, Hurvitz SA, Martin M, Kiermaier A, Lewis Phillips G, Xu J, Helms H-J, Slamon D, Press MF. Biomarker analysis from the neoadjuvant KRISTINE study in HER2-positive early breast cancer (EBC) [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 P6-07-09.

Abstract P4-22-13: Everolimus plus trastuzumab and paclitaxel as first-line therapy in women with HER2+ advanced breast cancer: Overall survival results from BOLERO-1

Background

Everolimus (EVE), an mTOR inhibitor has shown activity in HER2+ advanced breast cancer (ABC) in both preclinical and clinical studies. In the pivotal BOLERO-1 trial (NCT00876395), the progression-free survival (PFS) was not significantly different between the EVE + trastuzumab (TRAS) + paclitaxel (PAC) combination and placebo (PBO) + TRAS + PAC in the full HER2+ population (EVE, 15.0 mo vs PBO, 14.5 mo; HR=0.89; 95% CI: 0.73-1.08; p=0.1166). Although not reaching protocol defined level for statistical significance, the hormone receptor negative (HR-) subpopulation appeared to benefit from EVE, with a 7.2 mo PFS benefit vs PBO arm (EVE, 20.3 mo vs PBO, 13.1 mo; HR=0.66; 95% CI: 0.48-0.91; p=0.0049). The final exploratory overall survival (OS) analysis from the study is presented here.

Methods

In this phase 3 randomized trial, 719 women with HER2+ ABC without prior TRAS or chemotherapy in the metastatic setting were randomized 2:1 to receive either EVE (10 mg/d) or placebo (PBO) and weekly PAC+TRAS, stratified by visceral metastasis (lung, liver, peritoneal or pleural: yes vs no) and prior adjuvant or neo-adjuvant treatment with TRAS (yes vs no). As the primary objectives (PFS on full population and on HR- subpopulation) of BOLERO-1 were not met, the key secondary endpoint of OS was not formally statistically tested. However, given the results of PFS, in particular in the HR- subpopulation, a change to the OS analysis plan was made by introducing one final exploratory OS analysis at the time of study termination.

Results

At data cutoff (Dec 31, 2015), the median duration of exposure was 40.8 weeks (range: 0.6-320.4) in the EVE arm and 48.1 weeks (range: 1.1-308.0) in the PBO arm. After a median follow-up of 60.3 mo, 350 deaths were recorded in the full population, 238 (49.6%) in the EVE arm and 112 (46.9%) pts in the PBO arm. In the full population, the median OS was comparable in the EVE vs PBO arms (48.6 mo vs 50.0 mo respectively; HR = 1.13; 95% CI: 0.90-1.42). In the HR- subpopulation, 138 deaths were recorded; 88 (42.3%) pts in the EVE arm and 50 (48.5%) pts in the PBO arm. In the HR- subpopulation, the median OS in the EVE arm was longer compared to PBO arm (57.0 mo vs 41.6 mo respectively; HR = 0.83; 95% CI: 0.59-1.18). Stomatitis, diarrhea, alopecia, cough, rash, pyrexia, neutropenia, and fatigue were the most frequent adverse events (AEs) reported in EVE arm (≥35%). AEs leading to dose interruption and/or change were reported in 441 (93.4%) pts in EVE arm and 165 (69.3%) pts in the PBO arm respectively. Overall, AEs leading to treatment discontinuation were reported in 262 (55.5%) pts in EVE arm and 98 (41.2%) pts in PBO arm. Serious AEs were reported in 171 (36.2%) pts in the EVE arm and 40 (16.8%) pts in the PBO arm respectively. On treatment AE related deaths were reported for 3.6% pts in the EVE arm and 0% pts in the PBO arm.

Conclusions

The median OS was similar in the EVE vs PBO arms for overall population. However, a prolongation of 15.4 mo in median OS of HR- subpopulation was observed in the EVE arm vs PBO arm in this exploratory analysis. Pts in the EVE arm had a manageable safety, consistent with the safety profile of EVE and no new safety signals were identified.

Citation Format: Yardley D, Hurvitz S, Jiang Z-f, Toi M, Burris H, Buyse M, Slamon D, Makhson A, Elsaid A, Lerzo G, Hellerstedt B, Nuzzo F, Sohn J, Manzyuk L, Cabaribere D, Lincy J, Weimann A, Noel-Baron F, Pacaud L, Andre F. Everolimus plus trastuzumab and paclitaxel as first-line therapy in women with HER2+ advanced breast cancer: Overall survival results from BOLERO-1 [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 P4-22-13.

Impact of palbociclib plus letrozole on pain severity and pain interference with daily activities in patients with estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer as first-line treatment

Background Palbociclib is a recently approved drug for use in combination with letrozole as initial endocrine-based therapy for the treatment of postmenopausal women with advanced estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+/HER2-) breast cancer. This report assesses the impact of palbociclib in combination with letrozole versus letrozole alone on patient-reported outcomes of pain. Methods Palbociclib was evaluated in an open-label, randomized, phase II study (PALOMA-1/TRIO-18) among postmenopausal women with advanced ER+/HER2- breast cancer who had not received prior systemic treatment for their advanced disease. Patients received continuous oral letrozole 2.5 mg daily alone or the same letrozole dose and schedule plus oral palbociclib 125 mg, given once daily for 3 weeks followed by 1 week off over repeated 28-day cycles. The primary study endpoint was investigator-assessed progression-free survival in the intent-to-treat population, and these results have recently been published (Finn et al., Lancet Oncol 2015;16:25-35). One of the key secondary endpoints was the evaluation of pain, as measured using the Brief Pain Inventory (BPI) patient-reported outcome tool. The BPI was administered at baseline and on day 1 of every cycle thereafter until disease progression and/or treatment discontinuation. Clinical trial registration This study is registered with ClinicalTrials.gov (NCT00721409). Results There were no statistically significant differences in Pain Severity or Pain Interference scores of the BPI between the two treatment groups for the overall population or among those with any bone disease at baseline. A limitation of the study is that results were not adjusted for the concomitant use of opioids or other medications used to control pain. Conclusions The addition of palbociclib to letrozole was associated with increased efficacy without negatively impacting pain severity or pain interference with daily activities.

Progression-free survival as surrogate end point for overall survival in clinical trials of HER2-targeted agents in HER2-positive metastatic breast cancer

BACKGROUND

The gold standard end point in randomized clinical trials in metastatic breast cancer (MBC) is overall survival (OS). Although therapeutics have been approved based on progression-free survival (PFS), its use as a primary end point is controversial. We aimed to assess to what extent PFS may be used as a surrogate for OS in randomized trials of anti-HER2 agents in HER2+ MBC.

METHODS

Eligible trials accrued HER2+ MBC patients in 1992-2008. A correlation approach was used: at the individual level, to estimate the association between investigator-assessed PFS and OS using a bivariate model and at the trial level, to estimate the association between treatment effects on PFS and OS. Correlation values close to 1.0 would indicate strong surrogacy.

RESULTS

We identified 2545 eligible patients in 13 randomized trials testing trastuzumab or lapatinib. We collected individual patient data from 1963 patients and retained 1839 patients from 9 trials for analysis (7 first-line trials). During follow-up, 1072 deaths and 1462 progression or deaths occurred. The median survival time was 22 months [95% confidence interval (CI) 21-23 months] and the median PFS was 5.7 months (95% CI 5.5-6.1 months). At the individual level, the Spearman correlation was equal to ρ = 0.67 (95% CI 0.66-0.67) corresponding to a squared correlation value of 0.45. At the trial level, the squared correlation between treatment effects (log hazard ratios) on PFS and OS was provided by R(2) = 0.51 (95% CI 0.22-0.81).

CONCLUSIONS

In trials of HER2-targeted agents in HER2+ MBC, PFS moderately correlates with OS at the individual level and treatment effects on PFS correlate moderately with those on overall mortality, providing only modest support for considering PFS as a surrogate. PFS does not completely substitute for OS in this setting.

Statistical controversies in clinical research: statistical significance-too much of a good thing …

The use and interpretation of P values is a matter of debate in applied research. We argue that P values are useful as a pragmatic guide to interpret the results of a clinical trial, not as a strict binary boundary that separates real treatment effects from lack thereof. We illustrate our point using the result of BOLERO-1, a randomized, double-blind trial evaluating the efficacy and safety of adding everolimus to trastuzumab and paclitaxel as first-line therapy for HER2+ advanced breast cancer. In this trial, the benefit of everolimus was seen only in the predefined subset of patients with hormone receptor-negative breast cancer at baseline (progression-free survival hazard ratio = 0.66, P = 0.0049). A strict interpretation of this finding, based on complex 'alpha splitting' rules to assess statistical significance, led to the conclusion that the benefit of everolimus was not statistically significant either overall or in the subset. We contend that this interpretation does not do justice to the data, and we argue that the benefit of everolimus in hormone receptor-negative breast cancer is both statistically compelling and clinically relevant.

Abstract PD02-01: Her2 expression measured by AQUA analysis on BCIRG-005 and BCIRG-006 predicts the benefit of Herceptin therapy

Introduction: There have been disparate results reported in breast cancer testing for HER2 assessment as measured by protein expression or DNA amplification, yet both tests are routinely used to prescribe the drug Herceptin (trastuzumab, Genentech, So San Francisco, CA). Typically, immunohistochemistry (IHC) staining intensity of 3+ or FISH copy ratio of ≥2.0 are used to establish the cutoff between a negative and a positive result. However, it is unclear whether positivity is correlated with differential response to therapy. We used Automated Quantitative Analysis (AQUA) and a fluorescent immunohistochemical assay to measure HER2 expression in cases scored by central laboratory FISH and also receiving Herceptin therapy. The intentions of the study were two-fold: first, to provide further validation of the AQUA technology as applied to the clinical measurement of HER2 expression in breast cancer and second, to examine the potential of drug response stratification within those patients that are considered positive.

Methods: AQUA fluorescence IHC staining was performed on a multi-cohort tissue microarray (TMA) set. The assay was constructed in the Genoptix CLIA laboratory per ASCO/CAP guidelines and with a cutpoint that was validated against IHC (with FISH reflex). The trial specimens tested were from the BCIRG-005/006 studies. BCIRG-005 had n=1544 cases all assessed as FISH- while the 006 cohort had n=1477 cases all assessed as FISH+. Disease free survival (DFS) was used as the variable in subsequent modeling and analysis.

Results: The BCIRG 005 and 006 cohorts, examined in aggregate, allowed for an initial examination of agreement relationships between HER2 levels as assessed by AQUA scoring and HER2 levels as assessed by central lab FISH. Results indicated a 77% negative agreement, a 97% positive agreement and an 87% overall concordance agreement for a total of n=3021 cases. Additional Cox modeling of the patients that were enrolled as FISH+ and stratified for those who did or did not receive Herceptin treatment demonstrated a significant overall hazard ratio (HR = 0.75, CI=0.60,0.93) and when stratified for response to Herceptin, cases determined to be positive by AQUA showed significant benefit from treatment (HR = 0.66, CI = 0.52,0.85) in contrast to those who were scored as negative by AQUA that did demonstrate benefit from therapy (HR = 1.19, CI=0.71,1.97).

Conclusions: Analysis of the cases in this study originally determined to be HER2+ by FISH indicates that AQUA may improve predictions of which patients will benefit from Herceptin therapy.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD02-01.

P1-12-06: The Role of MAPK and PI3K/AKT/mTOR Signaling in Innate Lapatinib Resistance

Background: Lapatinib is a tyrosine kinase inhibitor which blocks downstream MAPK and P13K/AKT/mTOR proliferation and survival signaling pathways in HER2 positive breast cancer cell lines, tumor xenografts and HER2 positive breast cancer patients. However, pre-clinical and clinical studies have shown that not all HER2 positive patients respond to lapatinib and thus innate resistance to lapatinib exists. The identification of biomarkers of lapatinib response is therefore critical and would enable individual therapeutic decisions to be based on tumor biology rather than basic histopathology data alone. The aim of this study was to examine the role of MAPK and PI3K/AKT/mTOR signaling in a panel of lapatinib sensitive and resistant HER2−amplified breast cancer cell lines to identify pharmacodynamic markers of response to lapatinib treatment.

Methods: Dose response curves were generated to determine sensitivity to lapatinib in a panel of 17 HER2−amplified breast cancer cell lines. Total and phosphorylated levels of HER2, HER3, EGFR, AKT, ERK, S6K and eEF2 were determined following 24 hours lapatinib treatment in each of the cell lines.

Results: Twelve of the cell lines were sensitive to lapatinib with IC50g &lt; 1 μM while 5 of the cell lines were innately resistant to lapatinib with IC50g &gt; 1 μM. Levels of pHER2 and pHER3 were decreased in response to lapatinib in all cell lines independent of sensitivity to lapatinib. This suggests that inhibition of HER2/HER3 activation is not indicative of response to lapatinib treatment. There was also no correlation between the levels of HER2, HER3, and EGFR and sensitivity to lapatinib in the cell line panel.

In lapatinib sensitive cell lines, lapatinib decreased PI3K (pAKT), mTOR (pS6K) and MAPK (pERK) signaling and increased peEF2 levels. In contrast the levels of pAKT, pS6K, peEF2 and pERK were maintained following lapatinib treatment in lapatinib resistant cells. The continued activation of these proteins in the presence of lapatinib suggests a possible feedback mechanism that warrants further investigation. These data confirm that maintained signaling through either the P13K/AKT/mTOR pathway or the MAPK pathways in the presence of lapatinib can be an early pharmacodynamic biomarker of response.

Conclusions: Maintenance of pAKT, pS6K, peEF2 and pERK levels, in response to lapatinib treatment correlates with lapatinib resistance. These data suggest that alterations in the P13K/AKT/mTOR and MAPK pathways play an important role in innate lapatinib resistance and pharmacologically targeting these pathways is a rational therapeutic approach for overcoming innate lapatinib resistance.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-12-06.

Abstract P3-10-24: Fibroblast Growth Factor Receptor 1 Amplification and Overexpression in Breast Cancer Tissue Microarrays Using Chromogenic In Situ Hybridization and Immunohistochemistry

Fibroblast growth factor receptors 1 (FGFR1) belongs to a subfamily of receptor tyrosine kinases (RTKs), which are involved in proliferation and apoptosis. FGFR1 amplification and mRNA overexpression occurs in ∼10% of breast cancers and has been associated with poor outcome. However, studies assessing FGFR1 amplification and protein overexpression in a large collection of breast tumors are lacking. In this prospective, we examined a series of primary breast cancers samples derived from the BCIRG trials assembled into 15 tissue microarrays. FGFR1 gene amplification was studied using chromogenic in situ hybridization (CISH) and evaluated with respect to association with level of protein expression and clinicopathological parameters. FGFR1 gene amplification was significantly associated with high protein levels as determined by immunohistochemistry (P&lt;0.0001, 3294 pts with available matched CISH and IHC records). Overall, the incidence of FGFR1 amplification found was 9.7% (160 out of 1646 pts. with available clinicopathological records) without a statistically significant difference between Her2- (78 out 720 pts., 11%) and Her2+ (82 out of 926 pts., 9%) cancers. In both cohorts, the hormone receptor-positive (ER+/PR+) cancers showed statistically significant higher levels of FGFR1 amplification compared to hormone receptor-negative tumors. In the analysis of the association of FGFR1 and the presence of PIK3CA mutations, the incidence of FGFR1 amplificationwas greatly reduced in mutant vs. wt PI3KCA tumors. In these cohorts, a clear relationship between FGFR1 amplification status and clinical outcome was not detected. Data from this large study confirms recently reported incidences of FGFR1 amplification in breast cancer and shows for the first time an association between FGFR1 gene amplification and protein overexpression. Moreover, the lower incidence of FGFR1 amplification in PIK3CA mutated cancers suggests that these are largely exclusive molecular events that could benefit from different targeted therapies.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-24.

Inhibition of IGF1R activity enhances response to trastuzumab in HER-2-positive breast cancer cells

BACKGROUND

although trastuzumab has improved the prognosis for HER-2-positive breast cancer patients, not all HER-2-positive breast tumours respond to trastuzumab treatment and those that initially respond frequently develop resistance. Insulin-like growth factor-1 receptor (IGF1R) signalling has been previously implicated in trastuzumab resistance. We tested IGF1R inhibition to determine if dual targeting of HER-2 and IGF1R improves response in cell line models of acquired trastuzumab resistance.

MATERIALS AND METHODS

HER-2, IGF1R, phospho-HER-2, and phospho-IGF1R levels were measured by enzyme-linked immunosorbent assays in parental and trastuzumab-resistant SKBR3 and BT474 cells. IGF1R signalling was targeted in these cells using both small interfering RNA (siRNA) and the tyrosine kinase inhibitor, NVP-AEW541.

RESULTS

IGF1R levels were significantly increased in the trastuzumab-resistant model, SKBR3/Tr, compared with the parental SKBR3 cell line. In both the SKBR3/Tr and BT474/Tr cell lines, inhibition of IGF1R expression with siRNA or inhibition of tyrosine kinase activity by NVP-AEW541 significantly increased response to trastuzumab. The dual targeting approach also improved response in the parental SKBR3 cells but not in the BT474 parental cells.

CONCLUSIONS

our results confirm that IGF1R inhibition improves response to trastuzumab in HER-2-positive breast cancer cells and suggest that dual targeting of IGF1R and HER-2 may improve response in HER-2-positive tumours.

Combining HSP90 Inhibition with Standard Therapies for HER2 Positive Breast Cancer

Background: HSP90 is required for the stability and activity of HER2 and downstream proteins, such as Akt, which play a key role in cell survival. We aimed to assess the anti-tumor effects of the HSP90 inhibitor NVP-AUY922 in HER-2 positive breast cancer cell lines.Methods: HER2 positive breast cancer cell lines with varied sensitivity to trastuzumab (Sensitive: BT474, SKBR3, MDA-MB-361; acquired resistance: BT474Res, SKBR3Res; innate resistance: HCC1419, HCC1954, MDA-MB-453) were treated with the HSP90 inhibitor NVP-AUY922 (Novartis) and trastuzumab. IC50s were determined using the acid phosphatase assay. HER2, Akt and HSP90 levels were determined by immunoblotting after treatment with NVP-AUY922. Combinations of NVP-AUY922 with trastuzumab were tested in BT474, BT474Res, SKBR3, SKBR3Res, HCC1954, and MDA-MB-361 cells. Combinations with docetaxel, cisplatin and 5'-deoxy-5-fluorouridine (5-DFUR) were tested in BT474, SKBR3, HCC1954, MDA-MB-453 and MDA-MB-361 cells.Results: All of the HER2 positive cells were sensitive to NVP-AUY922, with IC50s ranging from 5.5 to 16.4 nM and NVP-AUY922 treatment reduced HER2 and Akt levels in a dose dependent manner. Combined treatment with NVP-AUY922 (10 nM) and trastuzumab (10 nM) showed significantly greater inhibition of growth than either trastuzumab or NVP-AUY922 alone in BT474 and BT474Res cell lines (p&lt;0.005). In SKBR3, SKBR3Res, HCC1954, MDA-MB-453 and MDA-MB-361 cells, dual treatment with NVP-AUY922 and trastuzumab did not significantly increase response compared to NVP-AUY922 alone (Table 1). Combinations of docetaxel, cisplatin or 5-DFUR with NVP-AUY922 were antagonistic in all cell lines tested (CI values &gt;1).Conclusions: This study demonstrates that NVP-AUY922 has anti-tumour activity in HER2 positive breast cancers regardless of sensitivity to trastuzumab. The antagonistic interactions observed for combinations of NVP-AUY922 with chemotherapy do not favour clinical evaluation of concurrent administration of NVP-AUY922 with chemotherapy. However, alternative scheduling or combinations with other targeted therapies warrants further investigation.Table 1: Percentage growth in response to NVP-AUY922 and trastuzumab. BT474BT474ResSKBR3SKBR3ResHCC1954MDA-MB-361Trastuzumab53.3 +/- 4.990.4 +/- 7.669.5 +/- 16.179.5 +/- 8.2102.9 +/- 15.558.4 +/- 3.3AUY92255.0 +/- 1.192.6 +/- 11.933.3 +/- 9.719.1 +/- 6.152.2 +/- 13.88.2 +/- 6.2Tras+AUY92222.0 +/- 2.3*59.7 +/- 17.5*30.6 +/- 7.518.3 +/- 4.347.2 +/- 3.42.5 +/- 2.2 

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5055.

PI3 Kinase Pathway Analysis in Tissue Microarrays Using Laser Capture Microdissection and Immunohistochemistry

Background. During the performance of the BCIRG trials primary patient tumor samples were obtained from paraffin blocks and assembled into 15 tissue microarrays, including 3000 samples from trial 005 (adjuvant taxol in Her2- node positive patients), 2200 in 006 (adjuvant herceptin in Her2+ high risk patients) and 300 in 007 (addition of platinum in Her2+ first line therapy). This array set was prepared prospectively, in anticipation of molecular epidemiologic studies of a variety of targets in relation to outcome. In order to address the potentially important role of the PIK3CA pathway in modulating outcome in different clinical situations we assessed components of the PIK3CA pathway by various methods.Methods. We analysed the expression of PTEN, Cyclin D1, p53 and Stathmin by immunohistochemistry using standard methods. All markers were scored by histoscore. Phospho S6 240 and phospho Akt 473 were assessed simultaneously by quantum dot immunofluorescence using automated image capture and segmentation. PIK3CA mutations were evaluated using SnaPshot analysis of laser captured TMA spots in a subset of approximately 2000 samples.Results. In the samples analyzed PIK3CA mutation had an incidence of 23%, with 9% being mutations in exon 9 and 13% in exon 20, with 0.5% being mutant in both exons. Initial analysis of the results prior to outcome analysis indicated that Stathmin expression, while being a robust marker with good dynamic range, did not appear to correlate with PTEN loss by IHC or with PIK3CA mutation.Conclusions. PIK3CA mutational analysis is feasible from TMA cores and gives mutation incidences similar to the published literature for archival material. Relationships of markers with outcome will be presented.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4043.

HSP90 inhibition in HER2-positive breast cancer cells

e14573

Background: HSP90 is required for the stability and activity of HER2 and downstream proteins, such as Akt, which play a key role in survival. We aimed to assess the anti-tumor effect of the HSP90 inhibitor NVP-AUY922 in HER-2 positive breast cancer cell lines. Methods: HER2 positive breast cancer cell lines with varied sensitivity to trastuzumab (Sensitive: BT474, SKBR3; acquired resistance: BT474Res, SKBR3Res; innate resistance: HCC1419, HCC1954, MDA-MB-453) were treated with the HSP90 inhibitor NVP-AUY922 (Novartis) and trastuzumab. IC50s were determined using the acid phosphatase assay. HER2, Akt and HSP90 levels were determined by immunoblotting after treatment with NVP-AUY922. Combinations of NVP-AUY922 with docetaxel, cisplatin and 5'-deoxy-5-fluorouridine (5-DFUR) were tested in BT474 and SKBR3 cells. Results: All of the HER2 positive cells were sensitive to NVP-AUY922, with IC50s ranging from 5.5 to 16.4 nM. Combined treatment with NVP-AUY922 (10 nM) and trastuzumab (10 nM) showed significantly greater inhibition of growth than either trastuzumab or NVP-AUY922 alone in BT474 and BT474Res cell lines (p<0.005). In SKBR3 and SKBR3Res cells, dual treatment with NVP-AUY922 and trastuzumab did not significantly increase response compared to NVP-AUY922 alone ( Table 1 ). Treatment with NVP-AUY922 resulted in a dose-dependent decrease in HER2 and Akt levels in trastuzumab-sensitive and -resistant cells. Combinations of docetaxel, cisplatin or 5-DFUR with NVP- AUY922 were antagonistic in both BT474 and SKBR3 cells (CI values >1). Conclusions: This study demonstrates that NVP-AUY922 has anti-tumor activity in trastuzumab-sensitive, and in both innate and acquired trastuzumab-resistant HER2 positive breast cancer cells. The antagonistic interactions observed for combinations of NVP-AUY922 with chemotherapy do not favour clinical evaluation of such combinations. However, combinations with other targeted therapies, such as trastuzumab, warrant further investigation.

[Table: see text]

[Table: see text]

BCIRG 007: First overall survival analysis of randomized phase III trial of trastuzumab plus docetaxel with or without carboplatin as first line therapy in HER2 amplified metastatic breast cancer (MBC)

LBA1008

Background: Based on preclinical synergism between docetaxel (T), carboplatin (C) and trastuzumab (H), BCIRG conducted a phase III trial in HER2-positive MBC to evaluate efficacy and safety of H in combination with T or TC. Methods: 263 patients (pts) with HER2 FISH+ MBC were randomized to TH (H with T 100mg/m2) or TCH (H with T 75mg/m2 and C AUC=6). Chemotherapy was given every 3 weeks (q3w) for 8 cycles with weekly H at 2mg/kg (loading dose of 4 mg/kg) followed by H q3w at 6 mg/kg until progression. Pts were stratified by centre and prior (neo) adjuvant taxane chemotherapy. Primary endpoint was Time To disease Progression (TTP). Secondary endpoints include overall survival, response rate, duration of response (DR), clinical benefit (CB) and safety. Results: 131 pts were treated in each arm Pt characteristics were well balanced in both groups. A first efficacy analysis was conducted at 204 events. There was no significant difference between TH and TCH in median TTP (11.1 vs 10.4 mos, p=0.57), ORR (73% in both arms), DR (10.7 vs 9.4 mos) and CB (67% in both arms). At 39 months of median follow-up, median overall survival was 36.40 and 36.57 months in TH and TCH arms respectively. More patients on TCH received the max number of chemotherapy cycles, and numerically fewer patients on TCH discontinued treatment as a result of non hematological toxicity. The most common gr 3/4 toxicities were: Neutropenic infection that was 16.8% vs 9.2% respectively for TH and TCH, thrombocytopenia (2% vs 15%), asthenia (5% vs 12%), anemia (5% vs 11%), and diarrhea (2% vs 10%). Two pts died (1.5%) due to sepsis in TCH. Absolute LVEF decline > 15 % were seen in 5.5 % vs 6.7 % of pts. One pt (0.8%) had a symptomatic CHF in TH arm. Conclusion: Both TH (T 100) and TCH (T 75) were highly effective treatment regimens in women having HER2-positive MBC, demonstrating high response rates, median TTP > 10 months, and median overall survival > 36 months in both TH and TCH. Cardiac toxicity was no significant problem with either treatment.

[Table: see text]

BCIRG 006: Docetaxel and trastuzumab-based regimens improve DFS and OS over AC-T in node positive and high risk node negative HER2 positive early breast cancer patients: Quality of life (QOL) at 36 months follow-up

19647

Background: The primary objective of the BCIRG 006 trial was to determine if the use of trastuzumab in early high-risk HER2-positive breast cancer significantly improved clinical outcomes. A secondary objective was to evaluate the QOL of patients receiving the 2 treatments. Methods: The BCIRG 006 trial compared adjuvant standard AC (doxorubicin/cyclophosphamide x 4 cycles) followed by docetaxel x 4 [AC-T] or 2 trastuzumab-containing regimens, AC followed by T with trastuzumab x 1 year [AC-TH] or TCarbo x 6 with trastuzumab x 1 year [TCH] in patients with node positive or high-risk node negative HER2-positive early breast cancer (n=3222). Results: The 2nd planned interim analysis, median follow-up at 36 months, showed that both AC-TH and TCH significantly improved the DFS and OS over the control (relative reduction risk of relapse 39% (P<0.0001) and 33% (P=0.0003) respectively, for AC-TH and TCH vs control). Relative reduction in the risk of death was 41% (P=0.0041) and 34% (P =0.017) respectively, for AC-TH and TCH vs control. Congestive heart failure occurred in 0.4% of patients in AC-T and TCH vs 1.9% of patients in AC-TH. Global safety profile was acceptable in all 3 arms and more favourable in TCH than AC-TH. QOL, a secondary endpoint of this trial, was assessed using the EORTC QLQC-30, BR-23, and EQ5D. We will present the primary QOL endpoints comparing Physical Function, Global Health Status, Future Perspectives, and Systemic Treatment Effects change scores from baseline to mid-chemotherapy, end of chemotherapy, and 12 months follow-up (with a 10% change considered clinically important). The proportion of patients with improved/stable/worsened QOL scores will be compared with chi-square tests. Other QOL exploratory analyses will be presented.

[Table: see text]

BCIRG 007: Serum HER2 levels in women with metastatic HER2-amplified breast cancer

1020

Background: BCIRG 007 is a multicenter, phase 3 randomized trial comparing docetaxel and trastuzumab (TH) with docetaxel, platinum salt (cisplatin or carboplatin) and trastuzumab (TCH) as first line chemotherapy in women with metastatic breast cancer (MBC). Women enrolled in the study had to have primary breast tumors with HER2 amplification as determined by centralized FISH analysis. Methods: We determined the percentage of subjects with HER2 amplification who had elevated (>15ng/mL) baseline levels of serum HER2 prior to the initiation of trastuzumab-based therapies. Baseline was considered to be the last available determination within 21 days prior to first treatment. Results: The median baseline serum HER2 levels was 75.8 ng/mL (range=8–3,280 ng/mL) for all subjects (n=123), with no statistical difference between subjects randomized to receive TH (median=65.9 ng/mL, n=64) and those randomized to receive TCH (median=89.9 ng/mL, n=59). Overall, 89% of the 123 subjects with HER2-amplified primary tumors had serum HER2 levels >15 ng/mL at the time of metastatic disease (86% in TH vs 92% in TCH). Conclusions: There was no statistical impact of baseline serum HER2 levels on any important clinical event: response to treatment, clinical benefit (response or stable disease for more than 24 weeks), disease progression or death. Conversely, when serum HER2 was measured over time, subjects with higher levels had an elevated risk of experiencing progressive disease (p=.003), even after adjustment for extent of disease (1 or 2 vs 3 or more organs involved) and presence of visceral disease. These analyses suggest that monitoring serum HER2 levels over the course of disease may be a means for detecting progressive disease in women with HER2 amplified breast cancer. Given the long intervals between the serum HER2 measurement and progression (up to 9 months), caution is required in interpreting these results.

No significant financial relationships to disclose.

A phase II study of neoadjuvant docetaxel/carboplatin with or without trastuzumab in locally advanced breast cancer: Response and cardiotoxicity

10515

Background: A phase II clinical trial was conducted to study the safety and efficacy of neoadjuvant docetaxel/carboplatin (T/C) with or without trastuzumab (H) in women with stage III breast cancer. Methods: Forty-eight of 75 planned primary breast cancer patients (T3 or T4, any N, M0), age between 18 and 80 have been enrolled. Four cycles of T (75 mg/m2) + C (AUC 6) were given every 3 weeks preoperatively. Patients with HER-2 amplified tumors (FISH +) were randomized to receive either weekly concurrent H or T/C alone preoperatively and T/C plus H postoperatively. Tumors were assessed clinically at baseline and after neoadjuvant therapy. Cardiac assessment consisted of medical history, EKG and LVEF (by echocardiogram or MUGA) at baseline and at the end of neoadjuvant chemotherapy. Results: Available data from 45 of 48 enrolled patients showed 49% (22 cases) with complete clinical response, with 54.5% being HER-2 (+) (12 cases). Stable disease was seen in one patient who was HER-2 (−) (2.2%). Of 37 with complete pathology verification, 11 (29.7%) showed pathologic complete response (pCR) of the primary tumor with 5 cases being HER-2 (+). Of the 22 HER-2 (+) cases that completed neoadjuvant treatment, 11 received T/C/H and 11 received T/C. pCR was noted in 36.4% of the T/C/H group and 9% of the T/C group. LVEF data is available from 43 patients during the neoadjuvant phase, showing 18.6% (8 cases) with decrease of ≥ 10% (5 patients in the T/C arm and 3 patients in the T/C/H arm), although none had cardiac symptoms or LVEF below the normal limit. Conclusions: T/C ± H is clinically active in patients with locally advanced breast cancer including a 30% pCR rate. The cardiotoxicity rates were comparable between patients who received T/C and T/C/H.

No significant financial relationships to disclose.

Phase II study of docetaxel (D) plus bevacizumab (B) in Her/2 negative metastatic breast carcinoma (MBC)

13047

Background: Taxol+Bevacizumab (B) has clinical activity in Her/2 negative chemotherapy naive MBC with a PFS (11.4 mo), RR (29.9%), and OS (28.4 mo). We are conducting a single arm Phase 2 trial to assess the efficacy of Docetaxel (D)+B. Primary endpoint: time to progression. Secondary endpoints: response rate (CR + PR), response duration, overall survival and safety. Methods: Eligibility criteria: MBC with no prior therapy; Her/2 negative by FISH, ECOG PS 0 or 1; measurable disease by RECIST, Hgb ≥ 9 g/dL, ANC ≥ 1.5 × 109/L, Platelet count ≥ 100 × 109/L, Creatinine ≤ 2.0 mg/dL, Total bilirubin ≤ 1.0 × upper limit of normal, no CNS metastasis, no MI or stroke within 6 mo, no GI perforation, no major surgery within 28 d, and no bleeding diathesis or coagulopathy. Pts receive B 15 mg/kg IV and D 75 mg/m2 IV Q 3 wk. Response assessed radiographically Q 3 cycles. Treatment is until disease progression or unacceptable toxicity. Results: Since Apr 2005, 43 of the planned 75 pts have been enrolled. 21 pts have had at least one assessment resulting in approximately 40% response rate. Common Gr3/4 AE’s have been neutropenia, febrile neutropenia, hypertension. Gr3 LVEF decline seen in one pt. No treatment related deaths occurred. Conclusions: D+ B is well tolerated, with no new safety concerns and manageable toxicities. D+B appears active in MBC. Updated efficacy and safety data will be presented. Study supported by Genentech, Inc. San Francisco, CA.

No significant financial relationships to disclose.