GeparSixto Trial Research Articles

Abstract PO2-03-09: Cost-effectiveness analysis of RAD51 functional biomarker for platinum sensitivity in the GeparSixto trial

Abstract Background: Homologous recombination repair deficiency (HRD) has long been recognized as a predictive biomarker for platinum sensitivity and is present in up to 60% of early triple negative breast cancers (TNBC). Different commercial and lab-developed assays to measure HRD are available, but they do not necessarily reflect homologous recombination functionality. Functional HRD, defined by a low score in RAD51 foci, is emerging as an accurate and dynamic biomarker to predict DNA damaging agents’ response. We performed a cost-effectiveness evaluation of the RAD51 test compared to tumor BRCA1/2 mutation (tBRCA1/2) or genomic HRD by Myriad Mychoice® to identify patients sensitive to platinum-based chemotherapy within the GeparSixto trial. Methods: The effectiveness measure was the primary outcome of the GeparSixto study: rate of pathological complete response (pCR), defined as ypT0 ypN0. The pharmacological costs were calculated following treatment protocol of GeparSixto where TNBC patients received neoadjuvant paclitaxel plus Myocet®-nonpegylated liposomal doxorubicin (PM) or PM plus carboplatin (PMCb), both arms including bevacizumab. Bevacizumab was excluded from the cost analysis as it is not administered by standard practice. The cost of a session/stay at the day hospital was added, as well as the cost of the test used, comparing 4 scenarios: All comers (assuming all patients receiving PMCb); RAD51 test (assuming RAD51 ≤10% received PMCb and RAD51 >10% received PM); tBRCA1/2 test (assuming tBRCA1/2 mutated received PMCb and tBRCA1/2 non-mutated received PM) and genomic HRD by Myriad Mychoice® (HRD score ≥42 received PMCb, and HRD score <42 received PM). The available commercial costs were considered for tBRCA1/2 and Myriad Mychoice®, and the VHIO performance cost was considered for the RAD51 test. Parameter uncertainties were assessed by means of one-way and probabilistic sensitivity analyses. Results: All comers total cost was 20,530€ per patient, with associated pCR rate of 54.5%. Functional RAD51 test was associated with a pCR probability of 55.1% with a Δ cost of 198€, as opposed to tBRCA1/2 which presented a pCR rate of 40.1% with a Δ cost of 814€, and genomic HRD with 47% pCR rate and the higher Δ cost of 1,023€ per patient, when compared to all comers. The incremental cost-effectiveness ratio (Δ cost/Δ pCR) was 33,000 for RAD51 test and dominated in both tBRCA1/2 and genomic HRD tests. These results were robust on one way and probabilistic sensitivity analyses. Conclusion: The most efficient scenarios are the functional RAD51 test and all comers. Both tBRCA1/2 and genomic HRD by Myriad Mychoice® scenarios provide worse health outcomes at a higher cost, based on the data of the GeparSixto trial. This study highlights the potential overall benefit of functional HRD biomarkers to predict PARPi sensitivity. Citation Format: Isabel Pimentel, Carles Forné, Alba Llop-Guevara, Misericòrdia Carles-Lavila, Violeta Serra, Montserrat Rué, Judith Balmaña. Cost-effectiveness analysis of RAD51 functional biomarker for platinum sensitivity in the GeparSixto trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-03-09.

MGMT promoter methylation in triple negative breast cancer of the GeparSixto trial.

Triple-negative breast cancer (TNBC) is typically treated with chemotherapeutic agents, including carboplatin (Cb), an DNA platinating agent. The O6-methylguanine-DNA-methyltransferase gene (MGMT) encodes for the protein O6-alkylguanine-DNA-alkyltransferase (MGMT protein). MGMT protein is involved in DNA repair mechanisms to remove mutagenic and cytotoxic adducts from O6-guanine in DNA. In glioblastoma multiforme, MGMT methylation status is a predictive biomarker for increased response to temozolomide therapy. It has been suggested, that MGMT protein may have relevance for cellular adaptation and could have an influence on resistance to carboplatin therapy. We investigated the influence of MGMT promoter methylation on pathologic complete response and survival of patients with TNBC treated in the neoadjuvant GeparSixto trial. In 174 of 210 available TNBC tumors a valid MGMT promoter methylation status was determined by pyrosequencing of 5 CpG islands. In 21.8%, we detected a mean MGMT promoter methylation >10%. Overall, MGMT promoter methylation was not significantly associated with pathological complete response (pCR) rate. After stratification for the two therapy arms with and without Cb no statistically significant differences in therapy response rates between the two MGMT promoter methylation groups could be observed. Our results show that different MGMT promoter methylation status is not related to different chemotherapy response rates in the TNBC setting in GeparSixto.

Abstract P2-08-10: Similarities between low hormone receptor positive and hormone receptor negative breast cancer: An analysis of 4366 patients from multicenter clinical trials

Abstract Background: Currently, patients with breast cancer (BC) with hormone receptor (HR) immunohistochemical expression between 1-9% are eligible to receive endocrine therapy. However, recent data suggest that these tumors express a basal-like molecular phenotype associated with triple negative BC (TNBC) rather than luminal phenotype associated with HR positive BC. Here, we aimed to determine the differences between strong HR positive, low HR positive and negative HR BC, in regard to responsiveness to neoadjuvant chemotherapy (NACT) and disease free survival (DFS) in large cohorts from GBG clinical trials. Methods: In this retrospective analysis of data from women with BC treated in the neoadjuvant GeparQuinto (n=2572), GeparSixto (n=588) and GeparSepto (n=1206) clinical trials, we compared patients with three HR phenotypes: low positive (ER and/or PR= 1-9%), strong positive (ER or PR= 10-100%), and negative (ER and PR= <1%), regarding pathological complete response (pCR, ypT0 ypN0) and DFS. A logistic regression model for endpoint pCR was performed on pooled data from all trials. Cox regression was used to model DFS for patients participating in GeparQuinto and GeparSixto trial, including 71 with low HR positive phenotype. The models were adjusted by age, tumor and nodal status, grading, Her2 status, histological type, stromal and tumor infiltrating lymphocytes and clinical trial. The survival model was additionally adjusted by pCR after NACT. Results: Patients median age was 49 years, the majority had clinical tumor stage 2 (54.1%), negative nodal status (54.7%), and Her2 negative tumors (72.4%). 85.1% of women had BC classified as no special histological type. The pCR rate across the studies was 26.2%. 145 (3.4%) patients had low HR positive, 2417 (57.3%) strong HR positive and 1658 (39.3%) HR negative tumors. After NACT, 16.3% of patients with strong HR positive BC achieved a pCR, while among those with HR negative and low HR positive tumors, pCR rates were 40.2% and 37.9%, respectively (p<0.001). In the adjusted logistic regression model, there was no statistically significant difference between low HR positive and HR negative tumors (OR: 1.34, 95%-CI: (0.84-2.13), p=0.222). But strong HR positive tumors had a significantly lower chance of achieving a pCR compared to low HR positives (OR 0.48, 95%-CI: 0.30-0.76, p=0.002). Patients with strong HR positive BC had a better DFS than patients with low HR positive tumors (hazard ratio 0.35, 95%-CI: 0.18-0.70, p=0.003). DFS was not significantly different between patients with HR negative and low HR positive tumors (hazard ratio 0.74, 95%-CI: 0.38-1.43, p=0.370). Conclusions: Similarly to patients with negative HR tumors, patients with low HR positive tumors have a better responsiveness to NACT and worse survival rates, compared to patients with strongly HR positive BC. We suggest that studies on treatment options for basal-like/TNBC, should also consider including patients with low HR positive tumors. Citation Format: Villegas SL, Lederer B, Untch M, Holms F, Ulmer H-U, Diebold K, Fasching PA, Weber K, Schmitt WD, Tesch H, Rezai M, Marmé F, Sinn B, Hackmann J, Schneeweiss A, Tannapfel A, Nekljudova V, Denkert C, Loibl S. Similarities between low hormone receptor positive and hormone receptor negative breast cancer: An analysis of 4366 patients from multicenter clinical trials [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-10.

Specific microRNA signatures in exosomes of triple-negative and HER2-positive breast cancer patients undergoing neoadjuvant therapy within the GeparSixto trial

BackgroundThe focus of this study is to identify particular microRNA (miRNA) signatures in exosomes derived from plasma of 435 human epidermal growth factor receptor 2 (HER2)-positive and triple-negative (TN) subtypes of breast cancer (BC).MethodsFirst, miRNA expression profiles were determined in exosomes derived from the plasma of 15 TNBC patients before neoadjuvant therapy using a quantitative TaqMan real-time PCR-based microRNA array card containing 384 different miRNAs. Forty-five miRNAs associated with different clinical parameters were then selected and mounted on microRNA array cards that served for the quantification of exosomal miRNAs in 435 BC patients before therapy and 20 healthy women. Confocal microscopy, Western blot, and ELISA were used for exosome characterization.ResultsQuantification of 45 exosomal miRNAs showed that compared with healthy women, 10 miRNAs in the entire cohort of BC patients, 13 in the subgroup of 211 HER2-positive BC, and 17 in the subgroup of 224 TNBC were significantly deregulated. Plasma levels of 18 exosomal miRNAs differed between HER2-positive and TNBC subtypes, and 9 miRNAs of them also differed from healthy women. Exosomal miRNAs were significantly associated with the clinicopathological and risk factors. In uni- and multivariate models, miR-155 (p = 0.002, p = 0.003, respectively) and miR-301 (p = 0.002, p = 0.001, respectively) best predicted pathological complete response (pCR).ConclusionOur findings show a network of deregulated exosomal miRNAs with specific expression patterns in exosomes of HER2-positive and TNBC patients that are also associated with clinicopathological parameters and pCR within each BC subtype.

Platinum Chemo for

In the prior GeparSixto trial, German investigators examined the effect of neoadjuvant platinum therapy for nearly 600 patients with triple-negative

Germline Mutation Status, Pathological Complete Response, and Disease-Free Survival in Triple-Negative Breast Cancer

The GeparSixto trial provided evidence that the addition of neoadjuvant carboplatin to a regimen consisting of anthracycline, taxane, and bevacizumab increases pathological complete response (pCR) rates in patients with triple-negative breast cancer (TNBC). Whether BRCA1 and BRCA2 germline mutation status affects treatment outcome remains elusive. To determine whether BRCA1 and BRCA2 germline mutation status affects therapy response in patients with TNBC. This secondary analysis of a randomized clinical trial used archived DNA samples and cancer family history of 315 patients with TNBC enrolled between August 1, 2011, and December 31, 2012, in the GeparSixto trial. In all, 291 participants (92.4%) were included in this multicenter prospective investigation. DNA samples were analyzed for germline mutations in BRCA1, BRCA2, and 16 other cancer predisposition genes. The pCR rates between the carboplatin and noncarboplatin arms were compared. Genetic analyses were performed at the Center for Familial Breast and Ovarian Cancer in Cologne, Germany; data analysis, November 1 through December 31, 2015. Proportion of patients who achieved pCR and disease-free survival after neoadjuvant treatment according to BRCA1 and BRCA2 germline mutation status. For pCR rates, the ypT0/is ypN0 definition was used as a primary end point. Of the 291 patients with TNBC, all were women; the mean (SD) age was 48 (11) years. The pCR rate in the carboplatin group was 56.8% (83 of 146) and 41.4% (60 of 145) in the noncarboplatin group (odds ratio [OR], 1.87; 95% CI, 1.17-2.97; P = .009). Pathogenic BRCA1 and BRCA2 germline mutations were present in 50 of the 291 patients (17.2%). In the noncarboplatin arm, the pCR rate was 66.7% (16 of 24) for patients with BRCA1 and BRCA2 mutations and 36.4% (44 of 121) for patients without (OR, 3.50; 95% CI, 1.39-8.84; P = .008). The high pCR rate observed in BRCA1 and BRCA2 mutation carriers (16 of 24 [66.7%]) was not increased further by adding carboplatin (17 of 26 [65.4%]). In contrast, carboplatin increased response rates in patients without BRCA1 and BRCA2 mutations: 66 of the 120 patients (55%) without BRCA1 and BRCA2 mutations achieved pCR in the carboplatin arm vs 44 of the 121 patients (36.4%) in the noncarboplatin arm (OR, 2.14; 95% CI, 1.28-3.58; P = .004). Patients without pathogenic BRCA1 and BRCA2 alterations showed elevated disease-free survival rates when carboplatin was added (without carboplatin, 73.5%; 95% CI, 64.1%-80.8% vs with carboplatin, 85.3%; 95% CI, 77.0%-90.8%; hazard ratio, 0.53; 95% CI, 0.29-0.96; P = .04). Under the nonstandard GeparSixto polychemotherapy regimen, patients without BRCA1 and BRCA2 germline mutations benefited from the addition of carboplatin and those with BRCA1 and BRCA2 mutations showed superior response rates without additive effects observed for carboplatin. clinicaltrials.gov Identifier: NCT01426880.

Abstract ES9-3: ES9-3 (Neo)adjuvant systemic therapy of TNBC: How much is enough?

Abstract The use of neoadjuvant chemotherapy in ER-negative cancers has become quite popular in patients with stage II and III breast cancers, since it gives us important information on long-term prognosis, based on the amount of residual disease burden at the time of definitive surgical resection. Two relatively large phase II randomized neoadjuvant clinical trials have explored the addition of carboplatin to an anthracycline/taxane based chemotherapy regimen for patients with stage II or III triple-negative breast cancers (TNBC): GeparSixto, in Europe, and CALGB40603, in the US. Despite significant differences in chemotherapy backbone, and frequency and duration of carbo administration, both trials showed that the addition of carboplatin significantly increased the rate of pCR from ∼ 40% to 54%. Both trials also reported a significant amount of added toxicity for the carboplatin arms, with a significant amount of patient not being able to complete their planned treatment. However, whereas the GeparSixto trial reported an improvement in 3-year disease-free survival (DFS), the CALGB40603 did not. Since neither of these studies was powered to address disease-free or overall survival benefit from the addition of carboplatin to neoadjuvant systemic chemotherapy, lack of precision from small sample sizes are likely responsible for the difference seen in DFS between these two trials. Additionally, there's not yet a confirmed correlation between increases in frequency of pCR and event-free survival (EFS). A recently pooled analysis by Cortazar et al. could not validate pCR as a surrogate endpoint for improved EFS and overall survival (OS): as some patients who achieve a pCR go on to relapse and many with residual disease never experience a recurrence, small differences in pCR may never translate to improvements in EFS. Long term effects of the added toxicity of carboplatin are also not known. At present, upon completion of neoadjuvant therapy, the standard of care for patients with TNBC (who have no clinical evidence of metastatic disease after surgical excision of the cancer regardless of burden of residual disease) is observation. But recently, preliminary data from a Japanese phase III trial (CREATE-X) that randomized patients with HER2-negative breast cancer with lack of pCR post-neoadjuvant chemotherapy to observation or capecitabine x 8 cycles showed that the addition of capecitabine provided a statistically significantly higher 5-year DFS and OS in the TNBC group. EA1131, an ongoing adjuvant randomized phase III clinical trial seeks to address if patients with basal-like TNBC, with high risk of recurrence due to residual disease post completion of neoadjuvant chemotherapy, have a higher DFS benefit from a platinum agent than from capecitabine. The results of this trial will ultimately help avoid exposing upfront unselected patients, many of whom will never relapse, to toxic therapy in the absence of long-term known benefit. In summary, the addition of a platinum agent routinely in the neoadjuvant setting in TNBC is still an individualized decision and not yet standard of care for all patients. The decision to use capecitabine in patients with residual disease post-neoadjuvant chemo may still be slightly premature, confirmatory results of EA1131 are eagerly awaited. Citation Format: Mayer IA. ES9-3 (Neo)adjuvant systemic therapy of TNBC: How much is enough? [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 ES9-3.

Abstract P1-09-02: Homologous repair deficiency (HRD) as measure to predict the effect of carboplatin on survival in the neoadjuvant phase II trial GeparSixto in triple-negative early breast cancer

Abstract Introduction Addition of carboplatin to anthracycline/taxane-based neoadjuvant chemotherapy has shown to improve pathological complete response (pCR; ypT0 ypN0) rates in patients with triple-negative breast cancer (TNBC) in two large phase II studies (GeparSixto: von Minckwitz et al, Lancet Oncol 2014, CALGB 40603: Sikov WM, J Clin Oncol 2015). Participants of the GeparSixto study showed an improvement of pCR rate from 36.9 to 53.2% (p=0.005) and DFS by absolute 9% (HR 0.56 95% CI 0.33-0.96] p=0.035) with the addition of carboplatin in the TNBC subgroup. No effect was observed in the HER2-positive subgroup. We here report results on homologous repair deficiency (HRD) status in relation to pCR and DFS in the TNBC subgroup. Patients and Methods In the GeparSixto trial (NCT01426880), patients were treated for 18 weeks with paclitaxel 80mg/m2 q1w and non-pegylated-liposomal doxorubicin (NPLD) 20mg/m2 q1w. Patients with TNBC (N=315) received concurrently bevacizumab 15mg/kg i.v. q2w until surgery. All patients were randomized 1:1 to receive concurrently carboplatin AUC 1.5-2 q1w vs no carboplatin. Carboplatin dose was reduced from AUC 2.0 to 1.5 by an amendment after 330 patients. Primary objective is pCR rate (ypT0 ypN0). Event free survival (EFS), and overall survival (OS) were secondary objectives. HR Deficiency status was assessed on FFPE material from pretherapeutic core biopsies. HR Deficiency was defined as either HRD score high or a BRCA mutation. Results HRD status was measurable in 193 of 315 TNBC patients. 101 patients of them were randomly assigned to receive carboplatin and 92 to no additional carboplatin. After median follow-up of 34.3 months 43 event free survival (EFS) events have been reported. HR deficiency was detected in 136 (70.5%) tumors of which 79 (58.1%) showed high HRD score with intact tBRCA. HR deficiency independently predicted pCR (ypT0is ypN0) (odds ratio (OR) 2.506, CI 1.243-5.051, p=0.009). Adding carboplatin to PM significantly increased the pCR rate from 36.6% to 63.2% in HR deficient tumors with intact tBRCA (p=0.018), only marginally from 61.9% to 72.7% in BRCA mutated tumors (p=0.406), and moderately from 20.0% to 40.7% in HR non-deficient tumors (p=0.086). In general, patients with HRD deficient tumors had a better ESF than non HRD deficient ones (HR 1.805 (0.985-3.309); p=0.0526). Patients with high HRD score had an insignificant trend towards an improved EFS compared to those with low HRD score (HR 1.546 (0.764-3.127) p=0.2223). HRD deficiency did not predict carboplatin effect in patients without BRCA mutation (HR 0.8617). In multivariable analysis, only therapy, clinical nodal status before treatment, and lymphocyte predominant breast cancer were significant prognostic on EFS. Conclusion Within the GeparSixto study HR deficiency (either HRD score high or BRCA mutation) was associated with a higher pCR in general and an improved EFS. The effect of carboplatin could not be predicted by HR deficiency in this relatively small study. However, the results will help to understand the role of HR deficiency and the value of the HRD score in TNBC especially in patients without BRCA mutation. Citation Format: von Minckwitz G, Timms K, Untch M, Elkin EP, Hahnen E, Fasching PA, Schneeweiss A, Salat CT, Rezai M, Blohmer J-U, Zahm D-M, Jackisch C, Gerber B, Klare P, Kümmel S, Paepke S, Schmutzler R, Chau S, Reid J, Hartman A-R, Nekljudova V, Weber KE, Loibl S. Homologous repair deficiency (HRD) as measure to predict the effect of carboplatin on survival in the neoadjuvant phase II trial GeparSixto in triple-negative early 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 P1-09-02.

Role of TP53 mutations in triple negative and HER2-positive breast cancer treated with neoadjuvant anthracycline/taxane-based chemotherapy.

BackgroundTP53 mutations are frequent in breast cancer, however their clinical relevance in terms of response to chemotherapy is controversial.Methods450 pre-therapeutic, formalin-fixed, paraffin-embedded core biopsies from the phase II neoadjuvant GeparSixto trial that included HER2-positive and triple negative breast cancer (TNBC) were subjected to Sanger sequencing of exons 5-8 of the TP53 gene. TP53 status was correlated to response to neoadjuvant anthracycline/taxane-based chemotherapy with or without carboplatin and trastuzumab/lapatinib in HER2-positive and bevacizumab in TNBC. p53 protein expression was evaluated by immunohistochemistry in the TNBC subgroup.ResultsOf 450 breast cancer samples 297 (66.0%) were TP53 mutant. Mutations were significantly more frequent in TNBC (74.8%) compared to HER2-positive cancers (55.4%, P < 0.0001). Neither mutations nor different mutation types and effects were associated with pCR neither in the whole study group nor in molecular subtypes (P > 0.05 each). Missense mutations tended to be associated with a better survival compared to all other types of mutations in TNBC (P = 0.093) and in HER2-positive cancers (P = 0.071). In TNBC, missense mutations were also linked to higher numbers of tumor-infiltrating lymphocytes (TILs, P = 0.028). p53 protein overexpression was also linked with imporved survival (P = 0.019).ConclusionsOur study confirms high TP53 mutation rates in TNBC and HER2-positive breast cancer. Mutations did not predict the response to an intense neoadjuvant chemotherapy in these two molecular breast cancer subtypes.

Abstract S2-04: Early survival analysis of the randomized phase II trial investigating the addition of carboplatin to neoadjuvant therapy for triple-negative and HER2-positive early breast cancer (GeparSixto)

Abstract Introduction Addition of carboplatin to anthracycline/taxane-based neoadjuvant chemotherapy has shown to improve pathological complete response (pCR; ypT0 ypN0) rates in patients with triple-negative breast cancer in two large phase II studies (GeparSixto: von Minckwitz et al. Lancet Oncol 2014; CALGB 40603: Sikov et al. J Clin Oncol 2015). Participants of the GeparSixto study with triple-negative tumors showed an improvement of pCR rate from 36.9 to 53.2% by the addition of carboplatin (p=0.005); however, no statistically significant difference in pCR rate was observed in the HER2-positive subgroup (36.8 vs 32.8%, respectively). A greater benefit with carboplatin was observed in patients with BRCA mutations or a high homologous recombination deficiency (HRD score) in the tumor (pCR rate of 30% compared to 10% for patients without HRD). So far, it is unknown whether these effects on pCR translate into a survival benefit for the patients. We here report an early survival analysis of the GeparSixto study. Patients and Methods In the GeparSixto trial (NCT01426880), patients were treated for 18 weeks with paclitaxel 80mg/m2 q1w and non-pegylated-liposomal doxorubicin (NPLD) 20mg/m2 q1w. Patients with TNBC (N=315) received concurrently bevacizumab 15mg/kg i.v. q2w until surgery. Patients with HER2+ disease (N=273) received concurrently trastuzumab 6(8)mg/kg q3w and lapatinib 750mg daily. All patients were randomized 1:1 to receive concurrently carboplatin AUC 1.5-2.0 q1w vs no carboplatin, stratified by subtype (HER2+ vs TNBC). Carboplatin dose was reduced from AUC 2.0 to 1.5 by an amendment after 330 patients. Primary objective was pCR rate (ypT0 ypN0). Loco-regional invasive recurrence free survival (LRRFS), distant-disease- free survival (DDFS), invasive disease-free survival (IDFS), and overall survival (OS) were secondary objectives. Results 595 patients were recruited (8/2011 - 12/2012) in 51 German centers. 296 patients were randomly assigned to receive carboplatin and 299 to no additional carboplatin, of whom 295 and 293 started treatment, respectively. So far, 82 events have been reported after a median of 28 months follow-up. Analysis of updated events by treatment arm in the full study population as well as in the TNBC and HRD subgroups will be presented. Conclusion Even if the GeparSixto study was not powered to show carboplatin effects on survival, the expected results will help to assess the overall benefit of carboplatin in TNBC and the power of pCR to predict for DFS and OS. Citation Format: von Minckwitz G, Loibl S, Schneeweiss A, Salat CT, Rezai M, Zahm D-M, Klare P, Blohmer J-U, Tesch H, Khandan F, Fasching PA, Jakisch C, Nekljudova V, Untch M. Early survival analysis of the randomized phase II trial investigating the addition of carboplatin to neoadjuvant therapy for triple-negative and HER2-positive early breast cancer (GeparSixto). [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 S2-04.

46P - p53 mutations in HER2 positive and triple negative breast cancer treated with neoadjuvant chemotherapy – A translational subproject of the GeparSixto trial

46P - p53 mutations in HER2 positive and triple negative breast cancer treated with neoadjuvant chemotherapy – A translational subproject of the GeparSixto trial

Tumor-infiltrating lymphocytes and response to neoadjuvant chemotherapy with or without carboplatin in human epidermal growth factor receptor 2-positive and triple-negative primary breast cancers.

Modulation of immunologic interactions in cancer tissue is a promising therapeutic strategy. To investigate the immunogenicity of human epidermal growth factor receptor 2 (HER2) -positive and triple-negative (TN) breast cancers (BCs), we evaluated tumor-infiltrating lymphocytes (TILs) and immunologically relevant genes in the neoadjuvant GeparSixto trial. GeparSixto investigated the effect of adding carboplatin (Cb) to an anthracycline-plus-taxane combination (PM) on pathologic complete response (pCR). A total of 580 tumors were evaluated before random assignment for stromal TILs and lymphocyte-predominant BC (LPBC). mRNA expression of immune-activating (CXCL9, CCL5, CD8A, CD80, CXCL13, IGKC, CD21) as well as immunosuppressive factors (IDO1, PD-1, PD-L1, CTLA4, FOXP3) was measured in 481 tumors. Increased levels of stromal TILs predicted pCR in univariable (P < .001) and multivariable analyses (P < .001). pCR rate was 59.9% in LPBC and 33.8% for non-LPBC (P < .001). pCR rates ≥ 75% were observed in patients with LPBC tumors treated with PMCb, with a significant test for interaction with therapy in the complete (P = .002) and HER2-positive (P = .006), but not the TNBC, cohorts. Hierarchic clustering of mRNA markers revealed three immune subtypes with different pCR rates (P < .001). All 12 immune mRNA markers were predictive for increased pCR. The highest odds ratios (ORs) were observed for PD-L1 (OR, 1.57; 95% CI, 1.34 to 1.86; P < .001) and CCL5 (OR, 1.41; 95% CI, 1.23 to 1.62; P < .001). Immunologic factors were highly significant predictors of therapy response in the GeparSixto trial, particularly in patients treated with Cb. After further standardization, they could be included in histopathologic assessment of BC.

Defining a Role and Predicting Benefit From Platinum-Based Therapy in Breast Cancer: An Evolving Story

There are three evolving stories that have the potential to improve outcomes for patients with localized triple-negative breast cancer (TNBC), a phenotypically defined breast cancer subtype that often occurs in individuals harboring germline BRCA1 mutations, including up to 20% of unselected individuals and 50% with a strong family history. When occurring sporadically without a germline mutation, TNBC shares many clinical and molecular features with BRCA1associated cancers, including defective DNA repair, which may be a result of methylation-induced silencing of BRCA or mutations in other genes that encode proteins involved in DNA repair. The first story, as exemplified in the article by Sikov et al that accompanies this editorial, is that the DNA–damaging agent carboplatin significantly improves the pathologic complete response (pCR) rate when added to a neoadjuvant chemotherapy regimen that includes a taxane, anthracycline, and alkylating agent, confirming the results of a similar trial. The second story involves using predictive biomarkers to identify tumors that are particularly sensitive to DNA-damaging agents, including germline mutations in genes that encode proteins that are essential for DNA damage repair and somatic markers that identify so-called BRCAness in sporadic cancers. The third story centers on using response to neoadjuvant therapy as a pharmacodynamic biomarker, exemplified by the strong inverse association between pCR in the breast and axilla and risk of recurrence. Although it is clear that platinum-containing agents are potentially useful in TNBC, it is unclear which patients benefit from them and how to best use them. The platinum story in breast cancer dates back to 1988, when Sledge et al noted partial responses in seven of 19 patients (47%) unselected for breast cancer subtype who received cisplatin as first-line therapy for metastatic disease. Other reports followed, confirming activity for cisplatin and carboplatin when used as first-line cytotoxic therapy in otherwise unselected patients, although efficacy was limited when used beyond first-line treatment, and attempts to combine platinum-containing agents with taxanes met with variable success. On the basis of preclinical data indicating synergy when platinum-based drugs were combined with trastuzumab in human epidermal growth factor receptor 2 (HER2)/neu positive disease, the carboplatin-docetaxel-trastuzumab regimen was found to be an effective adjuvant regimen, although adding carboplatin to a trastuzumab-taxane regimen in metastatic disease produced only modest clinical benefit. This brings us to the next chapter in the evolving platinum story, which includes two randomized phase II neoadjuvant trials in TNBC. The first report of the GeparSixto trial by von Minckwitz et al included 293 patients with operable and locally advanced TNBC who received weekly paclitaxel and liposomal doxorubicin plus bevacizumab, either alone or in combination with weekly carboplatin (area under the curve [AUC] 2, then reduced to AUC 1.5) for up to 18 weeks. The addition of carboplatin significantly improved the pCR rate in the breast and axilla (58% v 37%; P .05), although it also substantially increased toxicity without affecting breast conservation rates. The second study, by Sikov et al from the Alliance Clinical Trials Group, included 493 patients with operable and locally advanced TNBC who received weekly paclitaxel for 12 weeks followed by doxorubicin-cyclophosphamide every 2 weeks. Paclitaxel was given alone or in combination with carboplatin (AUC 6 every 3 weeks for four cycles); using a 2 2 factorial design, patients were also randomly assigned to receive chemotherapy alone or in combination with bevacizumab. The addition of carboplatin was associated with an improved pCR rate in the breast and axilla (54% v 41%; P .0029); similar benefits were observed in the absence (49% v 39%) and presence (60% v 43%) of bevacizumab. Although numerically more patients who were not initially considered candidates for breast conservation were deemed potential candidates after therapy when carboplatin was used (57% v 44%), the difference was not statistically significant, and the actual rates were not reported. Neither trial was adequately powered to determine carboplatin-reduced recurrence, nor were patients observed long enough to observe such a difference if it existed. Why use platinum-containing agents in TNBC? This brings us to our second evolving story, dating back to 2000, when it was recognized that BRCA-mutant cells were sensitized to the antineoplastic effects of DNA-damaging agents such as platinum, and that neoadjuvant platinum monotherapy was highly effective in BRCA mutation– associated breast cancer. It was also recognized that sporadic TNBC JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 33 NUMBER 1 JANUARY 1 2015

Expression of immunologic genes in triple-negative and HER2-positive breast cancer in the neoadjuvant GEPARSIXTO trial: Prediction of response to carboplatin-based chemotherapy.

510 Background: We have recently described tumor-infiltrating lymphocytes (TILs) as predictors of pathological complete response (pCR = ypT0ypN0) to neoadjuvant carboplatin-based chemotherapy in the GeparSixto breast cancer (BC) trial. To further dissect the immunological status in tumor tissue we have evaluated a total of 12 immunologically relevant genes, including T-cell markers, B-cell markers, chemokines and immunoregulatory factors, in 481 pretherapeutic FFPE samples. Methods: GeparSixto investigated the addition of carboplatin to a doxorubicin/taxane combination in HER2-positive (HER2+) or triple-negative (TN) primary BC. Trastuzumab and lapatinib were added for HER2+ disease and bevacizumab for TN disease. Expression of 12 immunologically relevant genes (CXCL9, CCL5, CD8A, CD80, CXCL13, IGKC, CD21, IDO1, PD-1, PDL1, CTLA4, FOXP3) was evaluated by quantitative RT-PCR in 481 core biopsies. Results: All immune mRNA markers showed a strong positive correlation with each other and with the stromal lymphocyte infiltrate. Hierarchical clustering revealed three different immune-subtypes of tumors with different expression of immunological genes and different amounts of tumor infiltrating lymphocytes. In the GeparSixto cohort all 12 immune markers were significantly linked to increased pCR rates in univariate analysis. 11 of the markers were also significant in multivariate analysis including clinical parameters. Some markers, such as CCL5, IDO1 and PDL1 provided predictive information even if controlled for TILs. CCL5, CD8A, CTLA4, IDO1 and PD1 showed a significant interaction with treatment (carboplatin vs. control) in the complete cohort. In TN disease CCL5 and CD8A provided predictive information for carboplatin response even after adjustment for TILs. Conclusions: Expression of immune marker mRNAs in BC is predictive for response to neoadjuvant chemotherapy. In GeparSixto, these immunological parameters can be used in addition to TILs to identify patients with increased response rates to carboplatin. The results should be validated in other breast cancer trials evaluating carboplatin therapy.

Abstract S1-06: Increased tumor-associated lymphocytes predict benefit from addition of carboplatin to neoadjuvant therapy for triple-negative and HER2-positive early breast cancer in the GeparSixto trial (GBG 66)

Abstract Background: We have recently described a significantly increased pCR rate in triple-negative breast cancer with addition of carboplatin to a non-pegylated liposomal doxorubicin/taxane (MC) combination in the neoadjuvant Geparsixto study (von Minckwitz et al, ASCO, 2013). Here we report the results of prospective biomarker analyses performed in Geparsixto. Methods: Geparsixto investigates the effect of adding carboplatin to MC for the treatment of patients with HER2+ve and triple-negative (TN) primary BC. All HER2+ve patients received trastuzumab and lapatinib, all TN patients received bevacizumab. As part of the central pathology assessment, we prospectively evaluated tumor-associated lymphocytes (TILs) in 580 core biopsies. We used the parameters stromal lymphocytes (strLy) and lymphocyte-predominant breast cancer (LPBC, ≥60%TILs) as previously described (Denkert et al, JCO, 2010). In addition, Ki67 (n = 588) was measured by immunohistochemistry and p53 mutations in Exons 5-8 (n = 444) were evaluated by Sanger sequencing. Pathological complete remission (pCR) was defined as ypT0ypN0. Results: 24.7% of the 588 patients had a LPBC. These patients had an increased pCR rate of 60.3%, compared to 35.8% for the non-LPBC tumors (p&amp;lt;0.0005). A similar result was observed for strLy as a continuous parameter, with an odds ratio of 1.21 (95%CI 1.13-1.30), per 10% increase in strLy (p&amp;lt;0.0005). The effect of the lymphocytic infiltrate was different in both therapy arms: For patients treated with MC, the pCR rate was moderately increased in LPBC (46.6% vs. 33.5% in non-LPBC tumors, p = 0.050). In contrast, in patients who received additional carboplatin to MC, the pCR rate was increased to 75% for LPBC tumors, compared to 38.1% for non-LPBC tumors (p&amp;lt;0.0005). This result was observed in both therapy groups: In TNBC patients treated with MC+carboplatin, the pCR rates were 76.2% for LPBC, compared to 52.2% for non-LPBC (p = 0.01). In Her2+ve patients treated with MC+carboplatin, the pCR rates were 73.1% for LPBC and 22.9% for non-LPBC (p&amp;lt;0.0005). In the multivariate analysis, LPBC (p&amp;lt;0.0005) as well as strLy (p&amp;lt;0.0005) were a significant predictor of pCR after adjustment for tumor size, nodal status, therapy, age, hormone receptor and HER2 status. Ki67&amp;gt;20% was associated with an increased pCR rate of 46.6%, compared to 27% in tumors with lower proliferation (p&amp;lt;0.0005). For Ki67, the pCR rates were similar in both therapy arms. Mutations in exons 5-8 of the p53 gene were not associated with changes in pCR rate, neither in the total population nor in the two treatment arms. Conclusion: Our results show that the interaction with host immune response is relevant for response to chemotherapy, this effect is particularly strong with the addition of carboplatin. Tumor-associated lymphocytes as a continuous parameter as well as LPBC as a tumor subgroup are predictive for response to neoadjuvant chemotherapy. In particular with regard to the relevant toxicity of the MC+carboplatin combination, the integration of immunological biomarkers would be helpful to identify the patients with the highest benefit from the addition of carboplatin. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S1-06.

Abstract YR02: Clinical – Early breast cancer

Abstract The past year has brought several major changes in the management of early stage breast cancer. First was evidence from two randomized phase III trials, including ATLAS (Lancet. 2013: 9; 381) and aTTom (ASCO 2013; abstract 5), that extending the duration of adjuvant tamoxifen therapy from 5 to 10 years reduced the risk of breast cancer recurrence, breast cancer mortality, and overall mortality. A pooled analysis of the 17,477 patients enrolled both trials showed that for patients who took tamoxifen for 10 years, although there was no benefit in years 5-9 during tamoxifen therapy, there was a 25% reduction in breast cancer mortality beginning at year 10 (hazard ratio [HR] 0.75, 95% CI 0.65-0.86; p = 0.00004) and a 16% reduction overall mortality (HR 0.84, 95% CI 0.77-0.93; p = 0.0007). Although there was an increase in the risk of endometrial cancer in ATLAS (2.20, p&amp;lt;0.0001) and aTTom (1.83, p = 0.02), there were far fewer excess endometrial cancers and deaths than breast cancer recurrences and deaths that were prevented. In other news regarding adjuvant endocrine therapy, an analysis of the BIG1-98 trial comparing letrozole with tamoxifen demonstrated that letrozole improved was superior in lobular carcinoma and luminal B ductal carcinoma, indicating that the benefits of letrozole over tamoxifen overall were driven by the benefits seen in these groups (SABCS 2012, abstract S1-1). Regarding other forms of systemic therapy, the GeparSixto trial showed that the additional of carboplatin significantly improved the pathologic complete response rate in patients with triple negative breast cancer when added to an anthracyclines-taxane neoadjuvant regimen (ASCO 2013, abstract 1004), the S0221 trial showed that standard dose biweekly paclitaxel was associated with more neurotoxicity when compared with adjuvant weekly paclitaxel without a reduction in the risk of recurrence (ASCO 2013, CRA1008), and the BEATRICE trial showed no benefit from adding bevacizumab to adjuvant chemotherapy (Lancet Oncol 2013;14:933). Regarding surgical therapy, two studies evaluated the role of sentinel node biopsy after neoadjuvant chemotherapy, including the SENTINA trial (Lancet Oncol 2013; 14: 609) and the Z1071 trial (SABCS 2012, abstract S2-1), revealing lower sentinel node detection rates (80% and 92%, respectively) and higher false negative rates (14.2% and 12.6%, respectively) than typically observed in patients not previously treated with neoadjuvant chemotherapy. Another trial (AMAROS 2013, LBA 1001) showed similar locoregional control rates when axillary radiation was compared with axillary dissection following a positive positive sentinel node biopsy, with less lymphedema associated with axillary dissection. Finally, the U.S. Food and Drug Administration (FDA) granted accelerated approval for the use of pertuzumab in combination with trastuzumab and docetaxel for neoadjuvant therapy based upon the results of the NeoSPHERE trial (Lancet Oncol 2012;13:25), the first drug to receive approval under the FDA's new guidance accepting pathologic complete response rate as an endpoint supporting accelerated approval, with full approval conditional on improved event free survival being demonstrated with additional followup in the same trial, or in other trials (N Eng J Med 2012:366;2438). Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr YR02.

A randomized phase II trial investigating the addition of carboplatin to neoadjuvant therapy for triple-negative and HER2-positive early breast cancer (GeparSixto).

1004 Background: Use of carboplatin in neoadjuvant chemotherapy (NACT) has never been prospectively examined in breast cancer. Cohort studies suggest a high sensitivity to DNA-damaging agents (e.g., carboplatin in triple negative breast cancer [TNBC]), which have a high prevalence of BRCA mutations. Two trials examining carboplatin in HER2+ metastatic disease have shown conflicting results, but one was biased by different dosage of docetaxel in treatment arms. GeparSixto investigates the impact of carboplatin in addition to an identical, optimized cytotoxic-targeted regimen on pathological complete response (pCR) in these two breast cancer subtypes. Methods: In GeparSixto trial (NCT01426880) patients were treated for 18 weeks with paclitaxel 80mg/m² q1w and non-pegylated-liposomal doxorubicin (NPLD) 20mg/m² q1w. HER2+ patients received concurrently trastuzumab 6(8) mg/kg q3w and lapatinib 750mg daily. TNBC patients received concurrently Bevacizumab 15mg/kg i.v. q2w. All patients were randomized 1:1 to receive concurrently carboplatin AUC 1.5-2 q1w vs not, stratified by subtype. Primary objective is pCR rates (ypT0 ypN0), secondary objectives are pCR rate in predefined subgroups or by other definitions, clinical response rate, compliance and tolerability of carboplatin. Carboplatin dose was reduced from AUC 2.0 to 1.5 by an amendment after 330 patients due to carboplatin-related toxicity at pre-planned safety analyses. Results: 595 patients were recruited (8/2011 - 12/2012) in 51 German centers, 299 did not receive carboplatin. Median age was 47/48 years (no carb/carb), 36.8/36.5% were postmenopausal; 14.0/13.3% had T3, 5.0/3.7% T4, 41.8/37.6% N+, 93.0/92.9% ductal invasive, 64.5/65.3% G3 tumors; 46.2/46.3% had HER2+, 53.8/53.7% TNBC. 225 patients had a SAE (149 no carb/177 carb) and 3 died (postoperative pneumonia; reduced general condition; acute myocardial infarct), all in no carb arms. Final analysis on primary endpoint will be presented. Conclusions: This is first study, evaluating efficacy and safety of the addition of carboplatin to anthracycline-taxane containing NACT in patients with primary HER2+ and TNBC. Clinical trial information: NCT 01426880.