Influence of HER2 expression on prognosis in metastatic triple-negative breast cancer-results from an international, multicenter analysis coordinated by the AGMT Study Group

BACKGROUND

Triple-negative breast cancer (TNBC) is associated with poor prognosis, and new treatment options are urgently needed. About 34%-39% of primary TNBCs show a low expression of human epidermal growth factor receptor 2 (HER2-low), which is a target for new anti-HER2 drugs. However, little is known about the frequency and the prognostic value of HER2-low in metastatic TNBC.

PATIENTS AND METHODS

We retrospectively included patients with TNBC from five European countries for this international, multicenter analysis. Triple-negativity had to be shown in a metastatic site or in the primary breast tumor diagnosed simultaneously or within 3 years before metastatic disease. HER2-low was defined as immunohistochemically (IHC) 1+ or 2+ without ERBB2 gene amplification. Survival probabilities were calculated by the Kaplan-Meier method, and multivariable hazard ratios (HRs) were estimated by Cox regression models.

RESULTS

In total, 691 patients, diagnosed between January 2006 and February 2021, were assessable. The incidence of HER2-low was 32.0% [95% confidence interval (CI) 28.5% to 35.5%], with similar proportions in metastases (n = 265; 29.8%) and primary tumors (n = 425; 33.4%; P = 0.324). The median overall survival (OS) in HER2-low and HER2-0 TNBC was 18.6 and 16.1 months, respectively (HR 1.00; 95% CI 0.83-1.19; P = 0.969). Similarly, in multivariable analysis, HER2-low had no significant impact on OS (HR 0.95; 95% CI 0.79-1.13; P = 0.545). No difference in prognosis was observed between HER2 IHC 0/1+ and IHC 2+ tumors (HR 0.89; 95% CI 0.69-1.17; P = 0.414).

CONCLUSIONS

In this large international dataset of metastatic TNBC, the frequency of HER2-low was 32.0%. Neither in univariable nor in multivariable analysis HER2-low showed any influence on OS.

Abstract P3-10-07: A 3-gene DNA methylation signature fails to predict response to bevacizumab in metastatic breast cancer patients treated within the TANIA phase III trial

Background: Biomarkers predicting response to bevacizumab containing therapy in metastatic breast cancer (MBC) are of urgent need. In a retrospective single-institution analysis we have previously shown that a 3-gene methylation signature (MLH1,POLKand TMBIM6) could discriminate between responders and non-responders to a bevacizumab-based therapy in two independent cohorts of patients with MBC with an AUC of 0.94 and 0.86, respectively (Gampenrieder SP et al. Theranostics. 2018. 8(8):2278-2288). Here, we present the validation of these findings within the prospective phase III trial TANIA (Vrdoljak E et al. Ann Oncol. 2016. 27(11):2046-52) randomizing 494 patients with HER2-negative MBC to chemotherapy plus bevacizumab or chemotherapy alone for two consecutive treatment lines (second- and third-line). All patients had already received bevacizumab-containing therapy in the first-line setting.

Patients and methods: DNA isolated from archival FFPE tumor samples was available from 200 patients consenting to optional translational research within the TANIA trial. Out of these, 176 samples were collected prior to first-line bevacizumab therapy and were analyzed retrospectively. Sufficient DNA for methylation analysis was available from 124 patients: 64 treated with chemotherapy plus bevacizumab and 60 treated with chemotherapy alone. All samples were isolated from the primary tumor. Quantitative methylation analysis was performed by pyrosequencing on the PyroMark Q24 Advanced System (Qiagen). PFS and OS analyses were performed in both study arms comparing “predicted responders” (PRED_R) versus “predicted non-responders” (PRED_NR) based either on median dichotomization or according to the cutoffs for individual CpG and the combined 3-CpG methylation logistic regression model.

Results:Out of the 124 evaluable patients, 32 (25.8%) were classified as PRED_R and 92 as RED_NR by the 3-gene methylation signature. PRED_R did not have a significantly different second-line PFS (HR 0.95, 95%CI 0.57-1.57; P = 0.84) or OS (HR 0.91, 95%CI 0.51-1.60; P = 0.73) when treated in the bevacizumab-containing study arm compared to PRED_NR. In addition, PRED_R did not show a longer PFS when treated with bevacizumab compared to PRED_R treated with chemotherapy alone (HR 0.95, 95%CI 0.59-1.54; P = 0.83). Furthermore, there was no difference in third-line PFS and the combination of second- and third-line PFS between PRED_R and PRED-NR in the bevacizumab arm. In the control arm, PRED_NR showed a statistically significant shorter PFS compared to PRED_R (HR 0.50, 95%CI 0.22-0.77; P = 0.006), but not OS (HR 0.95, 95%CI 0.51-1.77; P = 0.86).

Conclusion: Our 3-gene methylation signature was not confirmed as predictive biomarker for bevacizumab efficacy in metastatic breast cancer.

(This research project was partially supported by ROCHE Austria GmbH)

Citation Format: Gampenrieder SP, Angela R, Rinnerthaler G, Hackl H, Steiner M, Pulverer W, Weinhaeusel A, Klinglmayr E, Karl T, Ilic S, Hufnagl C, Hauser-Kronberger C, Egle A, Greil R. A 3-gene DNA methylation signature fails to predict response to bevacizumab in metastatic breast cancer patients treated within the TANIA phase III trial [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 P3-10-07.

Abstract OT3-07-01: Ixazomib in combination with carboplatin in pretreated women with advanced triple negative breast cancer, an ongoing phase I/II trial (AGMT MBC-10 trial)

Background:Triple-negative breast cancer (TNBC) comprises a heterogeneous group of diseases which are generally associated with poor prognosis. Recently, the PARP inhibitor olaparib was approved as first targeted treatment beyond antiVEGF therapy for the BRCA1/2 mutated subgroup of TNBC. However, cytotoxic agents still remain the mainstay of treatment for this breast cancer subtype. Ixazomib is a selective and reversible inhibitor of the proteasome, which has been mainly investigated as treatment of multiple myeloma. In a preclinical cell line model for TNBC the first-generation proteasome inhibitor bortezomib showed synergistic efficacy with cisplatin. Clinical data are available for carboplatin plus bortezomib in metastatic ovarian and lung cancers showing remarkable antitumor activity (47% and 38% response rate, respectively) and good tolerability. In solid tumors cytotoxic effect of proteasome inhibitors is thought to be mediated through different mechanisms: (1) Inhibition of the Fanconi Anemia and BRCA1 DNA repair mechanism (2) Inhibition of p53 degradation (3) Inhibition of NF-kappa B signaling cascade. Based on this evidence, the phase I/II MBC-10 trial will evaluate the toxicity profile and efficacy of the oral second-generation proteasome inhibitor ixazomib in combination with carboplatin in patients with advanced TNBC. Trial Design: Patients with metastatic TNBC pretreated with at least one prior line of chemotherapy for advanced disease with a confirmed disease progression and measurable disease are eligible for this study.Patients will receive ixazomib in combination with carboplatin on days 1, 8, and 15 in a 28-day cycle. The phase I part of this study uses an alternate dose escalation accelerated titration design. After establishing the maximum tolerated dose (MTD), accrual continues to evaluate the efficacy and safety of the combination (phase II, including 41 evaluable patients). All patients will continue on study drugs until disease progression, unacceptable toxicity or discontinuation for any other reason. Primary endpoint of the phase II is overall response rate, secondary endpoints include safety profile, progression-free survival and quality of life. The MBC-10 trial is accompanied by a broad biomarker program investigating predictive biomarkers for treatment response and potential resistance mechanisms to the investigational drug combination. This trial is open for patient enrollment since November 2016 in six Austrian cancer centers. Accrual is planned to be completed within two years. ClinicalTrials.gov Identifier: NCT02993094

Citation Format: Rinnerthaler G, Gampenrieder SP, Petzer A, Burgstaller S, Voskova D, Rossmann D, Balic M, Egle D, Rumpold H, Singer CF, Petru E, Melchardt T, Ulmer H, Mlineritsch B, Greil R. Ixazomib in combination with carboplatin in pretreated women with advanced triple negative breast cancer, an ongoing phase I/II trial (AGMT MBC-10 trial) [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 OT3-07-01.

Abstract OT2-07-11: Ixazomib in combination with carboplatin in pretreated women with advanced triple negative breast cancer, a phase I/II trial (AGMT MBC-10 trial)

Background: Triple-negative breast cancer (TNBC) comprises a heterogeneous group of diseases which are generally associated with a poor prognosis. Up to now, no targeted treatment beyond anti-VEGF therapy is approved for TNBC so far and cytotoxic agents are the mainstay for the treatment of advanced tumor stages. Ixazomib is a selective, and reversible inhibitor of the proteasome, which has been mainly investigated in the treatment of multiple myeloma. In a preclinical study triple-negative breast cancer cells were treated with bortezomib, a first generation proteaseome inhibitor, alone and in combination with cisplatin, which had a synergistic effect. Clinical data are available for carboplatin plus bortezomib in metastatic ovarian and lung cancers showing remarkable antitumor activity and good tolerability. Based on this rational, the MBC-10 trial will evaluate the toxicity profile and efficacy of ixazomib in combination with carboplatin in patients with advanced TNBC.

Trial Design: Patients with metastatic TNBC pretreated with at least one prior line of chemotherapy for advanced disease with a confirmed disease progression and measurable disease are eligible for this study. Patients will receive ixazomib in combination with carboplatin on days 1, 8, and 15 in a 28-day cycle. The phase I part of this study uses an alternate dose escalation accelerated titration design. After establishing the maximum tolerated dose (MTD), accrual continues to evaluate the efficacy and safety of the combination (phase II, including 41 evaluable patients). All patients will continue on study drugs until disease progression, unacceptable toxicity or discontinuation for any other reason. Primary endpoint of the phase II is overall response rate, secondary endpoints include safety profile, progression-free survival and quality of life. This trial is open for patient enrollment since November 2016 in six Austrian cancer centers. Accrual is planned to be completed within two years. ClinicalTrials.gov Identifier: NCT02993094

Citation Format: Rinnerthaler G, Gampenrieder SP, Petzer A, Pusch R, Fridrik M, Rossmann D, Balic M, Egle D, Rumpold H, Singer C, Bartsch R, Melchardt T, Ulmer H, Mlineritsch B, Greil R. Ixazomib in combination with carboplatin in pretreated women with advanced triple negative breast cancer, a phase I/II trial (AGMT MBC-10 trial) [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 OT2-07-11.

Abstract P2-09-09: Polyligand profiling differentiates cancer patients according to their benefit of treatment

Introduction: Deconvolution of multi-nodal perturbations in cancer network architecture demands highly multiplexed profiling assays. We demonstrate the value of polyligand profiling of tumor systems states using libraries of single stranded oligodeoxynucleotides (ssODN) to distinguish between tumor tissue from breast cancer patients who did or did not derive benefit from treatment regimens containing trastuzumab.

Methods: This study included cases from women with invasive breast cancer who received chemotherapy+ trastuzumab (C+T) or trastuzumab monotherapy with available retrospective data on the time to next treatment (TTNT). A library of 2x1012 unique ssODN was exposed to FFPE tissues from patients who benefited (B) or not (NB) from trastuzumab-based regimens in several rounds of positive and negative selection. Two enriched libraries were screened on independent set of 42 B and 19 NB cases using a modified IHC protocol for detection of bound ssODNs. Poly-Ligand Profiles (PLP) were scored by a blinded pathologist. Two libraries, EL-NB and EL-B, showed significant p-values between groups of responders and non-responders. A Cox-PH model was fitted using either tumors' HER2 status or PLP test results as the independent variable. Median survival time was calculated from the Kaplan-Meier estimate. A separate group of 63 cases with TTNT data from chemotherapy without trastuzumab was used as a control to distinguish prognostic from predictive performance.

Results: The PLP scores of EL-NB and EL-B were assessed by receiver operating characteristic (ROC) curves and resulted in a combined AUC value of 0.81. EL-NB and EL-B were able to effectively classify B and NB patients with either HER2-negative/equivocal (AUC = 0.73) or HER2-positive cancers (AUC = 0.84). In contrast, HER2 status alone yielded an AUC value of 0.47. The combined PLP scores for the independent set of 63 patients treated with C excluding trastuzumab resulted in an AUC value of 0.53, indicating that the assay was predictive and not simply prognostic. Kaplan-Meier curves analysis shows that PLP+ cases have 429 days median TTNT, while PLP- cases have 129 days (HR = 0.38, log-rank p = 0.001). Analysis based on HER2 status showed no significant difference in TTNT between patients that were HER2+ (280 days) or HER2-negative/equivocal (336 days, HR = 1.27, log-rank p =0.45).

Summary: Performance of the PLP assay in differentiating patients who did or did not benefit from trastuzumab therapy outperforms the standard IHC assay for HER2 status. These results represent a promising step towards the development of a CDx to identify the 50-70% of HER2+ patients who will not benefit from trastuzumab. In addition, PLP also has the potential to identify the HER2-negative/equivocal patients who may benefit from trastuzumab-containing regimens.

Citation Format: Domenyuk V, Gatalica Z, Santhanam R, Wei X, Stark A, Kennedy P, Toussaint B, Levenberg S, Wang R, Xiao N, Greil R, Rinnerthaler G, Gampenrieder S, Heimberger AB, Berry DJ, Barker A, Demetri GD, Quackenbush J, Marshall JL, Poste G, Vacirca JL, Vidal GA, Schwartzberg LS, Halbert DD, Voss A, Miglarese MR, Famulok M, Mayer G, Spetzler D. Polyligand profiling differentiates cancer patients according to their benefit of treatment [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 P2-09-09.

Abstract P4-02-02: Contrast-enhanced MRI does not accurately predict pathologic complete response (pCR) after neoadjuvant chemotherapy in early or locally advanced breast cancer

Background: Patients with early or locally advanced breast cancer achieving a pathologic complete response (pCR) after neoadjuvant chemotherapy have a lower risk for recurrence or death compared to patients with residual invasive cancer. In the future, breast surgery might be avoided in patients in whom the presence of residual tumor after neoadjuvant therapy can be ruled out with very high confidence. Magnetic resonance imaging (MRI) has been shown to be the most accurate radiologic tool in breast cancer diagnostics and follow-up care. Therefore, we investigated the diagnostic accuracy of contrast-enhanced MRI to predict a pathological complete remission after neoadjuvant chemotherapy.

Methods: This retrospective study included all non-metastatic breast cancer patients treated with neoadjuvant chemotherapy followed by a contrast-enhanced MRI and breast cancer surgery at our institution between 09/2006 and 05/2016. Three specialized breast radiologists, blinded to the clinical and pathological data, reevaluated all preoperative MRI scans and recorded the presence or absence of contrast enhancement as indicator for residual cancer. pCR was defined as no invasive tumor in breast and axilla (ypT0/is N0), however 3 alternative definitions were investigated as well (ypT0 N0, ypT0/is and ypT). Cross tables were used to calculate sensitivity, specificity, pCR-predictive value (PPV), non-pCR-predictive value (NPV) and accuracy. P-values reflecting PPV and NPV differences between various patient subgroups were calculated with Fisher's exact test. The Kaplan-Meier method was used for estimates of distant-recurrence-free survival (DRFS) and overall survival (OS).

Results: In total, 246 patients fulfilled the inclusion criteria and were evaluated. Overall pCR and radiologic complete remission (rCR) rate were 29% and 45%, respectively. Only 48% of rCR corresponded to a pCR (PPV). Conversely, in 87% of cases, residual tumor in the MRI was pathologically confirmed (NPV). The sensitivity to detect a pCR was 75%, while specificity and accuracy were 67% and 69%, respectively. The diagnostic performance of MRI to predict treatment response varied between different histologic and molecular tumor subtypes, however there were little differences between the 4 pCR definitions. The PPV was significantly lower in the hormone-receptor(HR)-positive subgroup compared with the HR-negative subgroup (33% vs. 61%; P = 0.004), especially in luminal-A-like (7%) and lobular carcinomas (0%), respectively. Despite the low concordance (Kohens kappa -0.1), the prognostic value for distant recurrence-free survival was similar between rCR (HR 0.29) and pCR (HR 0.27), respectively. The median pathologic tumor size of residual disease in false-positive cases (rCR but no pCR) was 0.7 cm (SD 0.98 cm).

Conclusion: Contrast-enhanced MRI does not accurately predict pCR after neoadjuvant chemotherapy in early or locally advanced breast cancer, especially in HR-positive tumors. However, in case of false rCR the dimension of residual disease is generally small. Since residual tumor tissue can be detected with high precision, preoperative breast MRI is still of value for operation planning.

Citation Format: Gampenrieder SP, Peer A, Weismann C, Meissnitzer M, Rinnerthaler G, Webhofer J, Westphal T, Popovscaia M, Meissnitzer T, Reitsamer R, Hauser-Kronberger C, Egger H, Hergan K, Mlineritsch B, Greil R. Contrast-enhanced MRI does not accurately predict pathologic complete response (pCR) after neoadjuvant chemotherapy in early or locally advanced 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 P4-02-02.

Abstract P6-07-10: DNA methylation signature predicting bevacizumab efficacy in metastatic breast cancer

Background: Biomarkers predicting response to bevacizumab containing therapy in breast cancer are still missing. Since epigenetic modifications can contribute to an aberrant regulation of angiogenesis and to treatment resistance, we investigated the influence of DNA methylation on bevacizumab efficacy.

Patients and methods: A genome-wide methylation profiling using the Illumina Infinium HumanMethylation450 BeadChip was performed in archival FFPE specimen of 36 patients with HER2-negative metastatic breast cancer treated with chemotherapy in combination with bevacizumab as first-line therapy (learning set). Based on objective response and progression-free survival (PFS) and considering ER expression, patients were divided in responders (R) and non-responders (NR). Differentially methylated gene loci (methylation variable position = MVP) and differentially methylated regions (DMR) between R and NR were identified. Only significant sites with a strong change in methylation levels (Δβ>0.15 or Δβ<-0.15), an area under the curve of at least 0.85 by logistic regression analysis, and/or sites in proximity to genes functionally involved in angiogenesis and carcinogenesis were selected and further validated. Validation was performed in 81 bevacizumab treated breast cancer patients (validation set) and in 15 patients treated with chemotherapy only (control set) using targeted bisulfite sequencing. Methylated gene loci were considered predictive if there was a significant association with outcome (PFS) in the validation set but not in the control set using Spearman rank correlation, Cox regression, and logrank test.

Results: In the learning set 435 MVPs (p<0.001) and 144 DMRs (adjusted combined p<0.0001 with at least 3 significant MVPs p<0.05 in the same region) showed significantly different methylation between R and NR. In R 152 sites were hypermethylated with a median change of methylation (Δβ) of 0.13; 283 sites were hypomethylated with a median Δβ of -0.09. A methylation signature of 48 genes was specified allowing a good separation between responders and non-responders (odds ratio=101, p<0.0001; data presented at the 38th SABCS 2015, P3-07-43). At least one methylated cytosine in close proximity to 24 of these genes showed a significant association with PFS in the validation set but was not (or in the other direction) in the control set. Based on these data the methylation signature predicting long lasting response to bevacizumab could be reduced to 24 genes including several genes involved in angiogenesis and carcinogenesis, respectively (FLT1 also known as VEGFR-1, MLH1, GNAS, APC, DKK3, WNT2B and COL4A1).

Conclusion: A 24-gene methylation signature can reproducible discriminate between responders and non-responders to a bevacizumab-based therapy in breast cancer and could help to identify patients deriving greater benefit from anti-VEGF agents.

Citation Format: Gampenrieder SP, Rinnerthaler G, Pulverer W, Weinhäusel A, Hufnagl C, Hackl H, Hauser-Kronberger C, Mlineritsch B, Greil R. DNA methylation signature predicting bevacizumab efficacy in metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-07-10.

Abstract P5-15-13: Capecitabine in combination with bendamustine in pretreated women with HER2-negative metastatic breast cancer: Final PFS results of a phase II trial (AGMT MBC-6)

Background: Capecitabine is a well-established treatment option in HER2-negative advanced breast cancer (ABC) patients. Bendamustine is a generally well tolerated cytotoxic drug. Since bendamustine has already shown anticancer activity in ABC we evaluated the efficacy and tolerability of bendamustine in combination with capecitabine in pretreated patients with ABC. Here we present the final PFS results of this phase II trial.

Patients and methods: MBC-6 is a non-randomized, multicenter, open-label, single-arm phase II study in patients with HER2-negative ABC (ClinicalTrials.gov: NCT01891227). All patients were pretreated with anthracyclines and/or taxans and had measurable disease according to RECIST 1.1. Patients received 1000 mg/m2 capecitabine twice daily on days 1 to 14 in combination with 80 mg/m2 bendamustine on day 1 and 8 of a 3-week cycle for a maximum of 6 cycles. Afterwards capecitabine was continued as monotherapy. The primary endpoint was overall response rate (ORR). Secondary endpoints were progression-free survival (PFS), clinical benefit rate (CBR), safety and quality of life.

Results: From September 2013 to May 2015, 40 patients were recruited in eight Austrian centers. Median age was 60 years (range 29-77). Twenty-five percent of patients had triple-negative disease (TNBC) and 93% showed visceral involvement. Sixty-five percent had received prior chemotherapy in the (neo)adjuvant setting and 63% for ABC (43% one line, 15% two lines, 5% three lines). All patients with ER-positive disease had received prior endocrine therapy.At data cut-off on 06/08/16 overall 39 of 40 patients had discontinued treatment with a median PFS of 7.0 months (95% CI 4.6-9.5), 7.4 months in ER-positive and 4.0 months in triple negative disease (TNBC), respectively. Twelve patients (30%) experienced at least one drug related non-hematological AE ≥ grade 3 during combination treatment and further 6 patients (15%) during capecitabine maintenance. Three grade 4 hematological AEs (neutropenia) were observed. One patient died as a result of restrictive cardiomyopathy, where a relationship to capecitabine cannot be excluded, but seems unlikely.

Conclusion: The combination of capecitabine and bendamustine shows promising efficacy and a moderate toxicity profile. Further evaluation of this drug combination is warranted.Background: Capecitabine is a well-established treatment option in HER2-negative advanced breast cancer (ABC) patients. Bendamustine is a generally well tolerated cytotoxic drug. Since bendamustine has already shown anticancer activity in ABC we evaluated the efficacy and tolerability of bendamustine in combination with capecitabine in pretreated patients with ABC. Here we present the final PFS results of this phase II trial.

Patients and methods: MBC-6 is a non-randomized, multicenter, open-label, single-arm phase II study in patients with HER2-negative ABC (ClinicalTrials.gov: NCT01891227). All patients were pretreated with anthracyclines and/or taxans and had measurable disease according to RECIST 1.1. Patients received 1000 mg/m2 capecitabine twice daily on days 1 to 14 in combination with 80 mg/m2 bendamustine on day 1 and 8 of a 3-week cycle for a maximum of 6 cycles. Afterwards capecitabine was continued as monotherapy. The primary endpoint was overall response rate (ORR). Secondary endpoints were progression-free survival (PFS), clinical benefit rate (CBR), safety and quality of life.

Results: From September 2013 to May 2015, 40 patients were recruited in eight Austrian centers. Median age was 60 years (range 29-77). Twenty-five percent of patients had triple-negative disease (TNBC) and 93% showed visceral involvement. Sixty-five percent had received prior chemotherapy in the (neo)adjuvant setting and 63% for ABC (43% one line, 15% two lines, 5% three lines). All patients with ER-positive disease had received prior endocrine therapy.At data cut-off on 06/08/16 overall 39 of 40 patients had discontinued treatment with a median PFS of 7.0 months (95% CI 4.6-9.5), 7.4 months in ER-positive and 4.0 months in triple negative disease (TNBC), respectively. Twelve patients (30%) experienced at least one drug related non-hematological AE ≥ grade 3 during combination treatment and further 6 patients (15%) during capecitabine maintenance. Three grade 4 hematological AEs (neutropenia) were observed. One patient died as a result of restrictive cardiomyopathy, where a relationship to capecitabine cannot be excluded, but seems unlikely.

Conclusion: The combination of capecitabine and bendamustine shows promising efficacy and a moderate toxicity profile. Further evaluation of this drug combination is warranted.

Citation Format: Rinnerthaler G, Gampenrieder SP, Voskova D, Petzer A, Hubalek M, Petru E, Hartmann B, Andel J, Balic M, Melchardt T, Ulmer H, Mlineritsch B, Greil R. Capecitabine in combination with bendamustine in pretreated women with HER2-negative metastatic breast cancer: Final PFS results of a phase II trial (AGMT MBC-6) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-15-13.

Abstract P1-13-10: Capecitabine in combination with bendamustine in pretreated women with HER2-negative metastatic breast cancer: Stage 1 results of a phase II trial (AGMT MBC-6)

Background: Although there is no single accepted standard of care after failure of anthracycline and taxane therapy in HER2-negative metastatic breast cancer, capecitabine is a well-established treatment option. Bendamustine is a hybrid cytotoxic drug because of its structural similarity to alkylating agents and purine and it is generally well tolerated. Since bendamustine has already shown anticancer activity in breast cancer we evaluated the efficacy and tolerability of bendamustine in combination with capecitabine in 40 patients with advanced breast cancer after anthracycline and/or taxane pretreatment.

Patients and methods: MBC-6 is a non-randomized, multicenter, open-label, single-arm phase II study in patients with HER2-negative advanced breast cancer (ClinicalTrials.gov identifier: NCT01891227). All patients were pretreated with anthracyclines and/or taxans in the (neo-)adjuvant and/or metastatic setting and measurable disease according to RECIST 1.1. had to be present at baseline. Following a two-stage Green-Dahlberg design, 20 subjects were accrued and treated within stage 1 of the study. The trial was planned to enroll further 20 patients if there were at least four subjects (20%) with a complete (CR) or partial response (PR). Eligible patients received 1000 mg/m2 capecitabine twice daily on days 1 to 14 in combination with 80 mg/m2 bendamustine on day 1 and 8 of a 3-week cycle. After a maximum of eight cycles capecitabine was continued as single drug therapy until disease progression or unacceptable toxicity. The primary endpoint was overall response rate (ORR). Secondary endpoints were progression free survival (PFS), clinical benefit rate (CBR), safety profile and quality of life. Here we report the efficacy and safety analysis of stage 1 patients.

Results: From September 2013 to May 2015, 40 patients were recruited in eight Austrian centers. Median age of the stage 1 cohort was 59 years (range 29-77), 80% and 20% of patients had an ECOG performance score of 0 and 1, respectively. Thirty-three percent had triple-negative disease, 85% had had (neo-)adjuvant treatment and 65% patients were pretreated with at least one chemotherapy line for metastatic disease (15% one line, 50% two lines, 40% three lines). In stage 1, ORR was 50% with 9 confirmed PR and 1 confirmed CR, and ORR was comparable between hormone receptor-positive and triple-negative disease (54% vs. 43%). CBR was 55%. At data cut-off on 05/28/15 overall 15 of 20 patients had discontinued treatment: 10 patients (50%) due to progressive disease, 3 (15%) because of adverse events (AEs) and 2 patients on their own decision (10%). Five patients (25%) experienced at least one drug related non-hematological AE ≥ grade 3: 2 diarrhea, 2 fatigue, 3 respiratory or viral infections, 1 dyspnea, 1 thromboembolic event (each grade 3). One grade 4 hematological AE (neutropenia) was observed. One patient died as a result of restrictive cardiomyopathy, where a relationship to capecitabine cannot be excluded, but seems unlikely.

Conclusion: The combination of capecitabine and bendamustine has a moderate toxicity profile and the response data of the stage 1 are promising. Final study results are awaited in the first half of 2016.

Citation Format: Rinnerthaler G, Gampenrieder SP, Fridrik M, Petzer A, Hubalek M, Petru E, Jäger T, Andel J, Balic M, Ulmer H, Mlineritsch B, Greil R. Capecitabine in combination with bendamustine in pretreated women with HER2-negative metastatic breast cancer: Stage 1 results of a phase II trial (AGMT MBC-6). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-13-10.

Abstract P3-07-43: DNA methylation patterns correlating with outcome in patients treated with first-line bevacizumab for metastatic breast cancer

Background: Biomarkers predicting response to bevacizumab containing therapy in breast cancer are of urgent need for a personalized treatment approach. DNA methylation is involved in regulation of angiogenesis and development of treatment resistance and could therefore provide predictive information for bevacizumab efficacy.

Patients and methods: A genome-wide methylation profiling using the Illumina Infinium HumanMethylation450 BeadChip was performed in FFPE specimen of 36 patients with HER2-negative metastatic breast cancer treated with chemotherapy in combination with bevacizumab as first-line therapy (discovery set). Twenty-eight (78%) samples came from primary tumor and 8 (22%) from metastasis (2 lung mets., 1 pleural met., 1 liver met., 2 soft tissue mets., 1 ovarial met, 1 bone marrow infiltration). Based on progression-free survival (PFS) and breast cancer subtype (ER+ vs. triple-negative) patients were divided in responder (R) and non-responder (NR). By biostatistical methods differences in the methylation pattern between R and NR were detected. The 48 most interesting genes (e.g. because of there involvement in angiogenesis or carcinogenesis) showing a differential methylation status between R and NR are currently validated in two further metastatic breast cancer cohorts treated with (main set) and without bevacizumab (validation set), respectively. These validated results will be presented at the meeting.

Citation Format: Gampenrieder SP, Rinnerthaler G, Weinhäusel A, Pulverer W, Hugnagl C, Hackl H, Romeder F, Monzo Fuentes C, Hauser-Kronberger C, Mlineritsch B, Greil R. DNA methylation patterns correlating with outcome in patients treated with first-line bevacizumab for metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-43.

Epirubicin and docetaxel with or without capecitabine as neoadjuvant treatment for early breast cancer: final results of a randomized phase III study (ABCSG-24)

BACKGROUND

This randomized phase III trial compared pathologic complete response (pCR) rates of early breast cancer (EBC) following neoadjuvant epirubicin-docetaxel (ED)±capecitabine (C), and evaluated the addition of trastuzumab in HER2-positive tumors.

PATIENTS AND METHODS

Patients with invasive breast cancer (except T4d) were randomly assigned to receive six 3-weekly cycles of ED (both 75 mg/m2)±C (1000 mg/m2, twice daily, days 1-14). Patients with HER2-positive disease were further randomized to receive trastuzumab (8 mg/kg, then 6 mg/kg every 3 weeks) or not. Primary end point: pCR rate at the time of surgery.

RESULTS

Five hundred thirty-six patients were randomized to ED (n=266) or EDC (n=270); 93 patients were further randomized to trastuzumab (n=44) or not (n=49). pCR rate was significantly increased with EDC (23.0% versus 15.4% ED, P=0.027), and nonsignificantly further increased with trastuzumab (38.6% EDC versus 26.5% ED, P=0.212). Rates of axillary node involvement at surgery and breast conservation were improved with EDC versus ED, but not significantly; the addition of trastuzumab had no further impact. Hormone receptor status, tumor size, grade, and C (all P≤0.035) were independent prognostic factors for pCR. Trastuzumab added to ED±C significantly increased the number of serious adverse events (35 versus 18; P=0.020), mainly due to infusion-related reactions.

CONCLUSION

These findings show that the integration of C into a neoadjuvant taxane-/anthracycline-based regimen is a feasible, safe, and effective treatment option, with incorporation of trastuzumab in HER2-positive disease.

CLINICAL TRIAL NUMBER

NCT00309556, www.clinicaltrials.gov.

Abstract P5-20-11: Bevacizumab in metastatic breast cancer: a retrospective matched-pair analysis

Background: In November 2011 the FDA withdrew accelerated approval of the breast cancer indication for bevacizumab, because “the drug has not been shown to be safe and effective for this use” (FDA Commissioner M. A. Hamburg, MD). The objective of this analysis was to evaluate efficacy and safety of bevacizumab in non-selected patients with stage IV breast cancer.

Patients and methods: All patients with metastatic breast cancer treated with bevacizumab in combination with chemotherapy in our institution between 2005 and 2011 were retrospectively analysed. At least 1 cycle of bevacizumab was required for safety analysis, 3 applications for efficacy evaluation. A control group was matched according to the following criteria: receptor status, line of treatment, chemotherapy backbone, visceral or non-visceral disease and age.

Results: A total of 213 patients fulfilled the inclusion criteria. All of them were evaluable for toxicity, 199 for response. 503 potential controls allowed a complete matching for 103 patients. Fifty-eight percent of patients received first-line, 15% second-line and 27% of patients beyond second-line treatment. Visceral metastases were present in 69% of patients in both groups. The most common chemotherapy backbones were paclitaxel, capecitabine and docetaxel with 44%, 32% and 19%, respectively.