BackgroundWe performed whole-exome sequencing of pretreatment biopsies and examined whether genome-wide metrics of overall mutational load, clonal heterogeneity or alterations at variant, gene, and pathway levels are associated with treatment response and survival.Patients and MethodsTwo hundred and three biopsies from the NeoALTTO trial were analyzed. Mutations were called with MuTect, and Strelka, using pooled normal DNA. Associations between DNA alterations and outcome were evaluated by logistic and Cox-proportional hazards regression.ResultsThere were no recurrent single gene mutations significantly associated with pathologic complete response (pCR), except PIK3CA [odds ratio (OR) = 0.42, P = 0.0185]. Mutations in 33 of 714 pathways were significantly associated with response, but different genes were affected in different individuals. PIK3CA was present in 23 of these pathways defining a ‘trastuzumab resistance-network’ of 459 genes. Cases with mutations in this network had low pCR rates to trastuzumab (2/50, 4%) compared with cases with no mutations (9/16, 56%), OR = 0.035; P < 0.001. Mutations in the ‘Regulation of RhoA activity’ pathway were associated with higher pCR rate to lapatinib (OR = 14.8, adjusted P = 0.001), lapatinib + trastuzumab (OR = 3.0, adjusted P = 0.09), and all arms combined (OR = 3.77, adjusted P = 0.02). Patients (n = 124) with mutations in the trastuzumab resistance network but intact RhoA pathway had 2% (1/41) pCR rate with trastuzumab alone (OR = 0.026, P = 0.001) but adding lapatinib increased pCR rate to 45% (17/38, OR = 1.68, P = 0.3). Patients (n = 46) who had no mutations in either gene set had 6% pCR rate (1/15) with lapatinib, but had the highest pCR rate, 52% (8/15) with trastuzumab alone.ConclusionsMutations in the RhoA pathway are associated with pCR to lapatinib and mutations in a PIK3CA-related network are associated with resistance to trastuzumab. The combined mutation status of these two pathways could define patients with very low response rate to trastuzumab alone that can be augmented by adding lapatinib or substituting trastuzumab with lapatinib.

Abstract Mammography (Mx) and breast ultrasound (US) are the most commonly used diagnostic imaging modalities to estimate primary tumor size at the time of diagnosis. However, there are uncertainties regarding their use in the context of neoadjuvant therapy to predict pathologic complete response (pCR) or event-free survival (EFS). In this study, we sought to determine the value of Mx and US in predicting outcomes in women with HER2-positive breast cancer treated within the Neoadjuvant Lapatinib and/or Trastuzumab Treatment Optimisation (Neo-ALTTO) trial. METHODS Neo-ALTTO enrolled 455 women with invasive HER2-positive breast cancer and compared rates of pCR to neoadjuvant lapatinib, trastuzumab, and their combination. Each anti-HER2 therapy was given alone for 6 weeks, followed by 12 weeks of the same therapy plus weekly paclitaxel prior to surgery. Mx and US were requested at baseline, week 6 and before surgery. Central imaging review was not pre-planned and two independent investigators (SDC and HAA Jr), blinded to assigned treatment and clinical outcomes, reviewed the measurements reported for each imaging modality and assigned the corresponding RECIST category of response. Responders were defined as patients who had either a partial or complete response (CR + PR). We evaluated the association between radiological response at week 6/surgery with both pCR and EFS. RESULTS A total of 340 (77%) and 267 (61%) pts had an evaluable US and Mx at weeks 6; and 309 (70%) and 248 (56%) pts had an evaluable US and Mx at the time of surgery. Early response (CR + PR) in the primary tumors was observed after 6 weeks of treatment in 32% pts by Mx and in 43% pts by US. pCR rates were twice as high for early responders than non-responders (week 6: 46% vs 23% by US, p =<0.0001; 41% versus 24% by Mx, p= 0.007). The positive predictive value of US and Mx at surgery were 57% and 53%, respectively; the negative predictive values were 72% and 81%. The results according to hormone receptor status were similar to those in the overall patient population.There was no significant relationship between response at ultrasound and/or at mammography at 6 weeks/surgery and EFS. CONCLUSION Our results show that both Mx and US are underused during neo-adjuvant treatment, and further recommendations regarding the use of both imaging modalities should be explored prospectively. US may be used to assess early response to preoperative treatment in patients with HER2 positive breast cancer receiving anti-HER2 therapies, whereas Mx appears to be more useful in detecting residual disease at the time of surgery. Citation Format: Di Cosimo S, Campbell C, Hazim Jr HA, Curigliano G, Criscitiello C, Crescenzo R, de la Pena L, Piccart-Gebhart MJ, Eidtmann H, Baselga J, de Azambuja E. Breast ultrasound and mammography and response to neoadjuvant lapatinib, trastuzumab and their combination in HER2 positive breast cancer: Results from Neo-ALTTO (BIG 1-06). [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 P6-01-04.

Abstract Background: We previously reported that nab-paclitaxel (nP) increases the pathological complete response (pCR, ypT0 ypN0) rate when it replaces solvent-based paclitaxel (P) as part of a sequential taxane followed by epirubicin/cyclophosphamide (EC) neoadjuvant chemotherapy for patients with early breast cancer (Untch et al. SABCS 2014). Here, we report efficacy and safety of patients being treated either with 150 mg/m2 nab-paclitaxel (nP150) before an amendment or with 125 mg/m2 nab-paclitaxel (nP125) thereafter in comparison to solvent-formulated paclitaxel at 80 mg/m2 (P80). Methods: In the GeparSepto study (NCT01583426), 1207 patients were randomized to either nP150 or P80 q1w for 12 weeks followed by 4 cycles of conventionally dosed EC (E: 90mg/m2; C: 600 mg/m2) q3w. The primary objective of the study was to compare the pCR rate (pCR, ypT0 ypN0). Patients with untreated, histologically confirmed uni- or bilateral, cT2- cT4d carcinoma, and no clinically relevant cardiovascular and other co-morbidities were included. Patients with HER2+ tumors received trastuzumab (loading dose 8mg/kg; 6 mg/kg) plus pertuzumab (loading dose 840 mg; 420 mg) q3w concomitantly to all chemotherapy cycles. After a safety analysis showed a higher rate of dose reductions and treatment discontinuations with nP150 compared to P80, weekly dose of nP was reduced to 125 mg/m2. Results: nP was given for the majority of cycles at a dose of 150 mg/m2 to 179 patients and at a dose of 125 mg/m2 to 426 patients. Treatment characteristics were fairly balanced between these two sequential cohorts as well as compared to 601 patients receiving P80 except for HER2 status (HER2-positive: nP150 22%, nP125 37% and P80 33%) and Ki67 (<20%: nP150 60%, nP125 73% and P80 69%). Taxane treatment was discontinued in 16% (nP150), 11% (nP125) and 6% (P80) of patients, respectively. Median dose per cycle (based on relative total dose intensity (RTDI)) was 129 mg/m2 with nP150, 119 mg/m2 with nP125 and 78 mg/m2 with P80, respectively. Peripheral sensory neuropathy (PNP) grade 3/4 (NCI-CTCAE v4.0) was observed in 15% with nP150, 8% with nP125 and 3% with P80, respectively. pCR was 32% with nP150, 41% with nP125 and 29% with P80 in all patients and 46% with nP150, 49% with nP125 and 26% with P80 in 277 patients with triple-negative breast cancer, respectively. Conclusions: Risk-benefit ratio of nP125 was improved over nP150 with better drug adherence and RTDI, lower frequency of PNP but a higher pCR rate. It should therefore be considered as the preferred schedule when nP is used as neoadjuvant treatment for primary breast cancer. The trial was financially supported by Celgene and Roche. Citation Format: von Minckwitz G, Untch M, Jakisch C, Schneeweiss A, Conrad B, Aktas B, Denkert C, Eidtmann H, Weibringhaus H, Kümmel S, Hilfrich J, Warm M, Paepke S, Just M, Hanusch C, Hackmann J, Blohmer J-U, Clemens M, Costa SD, Gerber B, Nekljudova V, Loibl S. nab-paclitaxel at a dose of 125 mg/m2 weekly is more efficacious but less toxic than at 150 mg/m2. Results from the neoadjuvant randomized GeparSepto study (GBG 69). [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 P1-14-11.

Background: We previously reported that nab-paclitaxel (nP) increases the pathological complete response (pCR, ypT0 ypN0) rate when it replaces solvent-based paclitaxel (P) as part of a sequential taxane followed by epirubicin/cyclophosphamide (EC) neoadjuvant chemotherapy for patients with early breast cancer (Untch et al. SABCS 2014). Here, we report efficacy and safety of patients being treated either with 150 mg/m 2 nab-paclitaxel (nP150) before an amendment or with 125 mg/m 2 nab-paclitaxel (nP125) thereafter in comparison to solvent-formulated paclitaxel at 80 mg/m 2 (P80). Methods: In the GeparSepto study (NCT01583426), 1207 patients were randomized to either nP150 or P80 q1w for 12 weeks followed by 4 cycles of conventionally dosed EC (E: 90mg/m 2 ; C: 600 mg/m 2 ) q3w. The primary objective of the study was to compare the pCR rate (pCR, ypT0 ypN0). Patients with untreated, histologically confirmed uni- or bilateral, cT2- cT4d carcinoma, and no clinically relevant cardiovascular and other co-morbidities were included. Patients with HER2+ tumors received trastuzumab (loading dose 8mg/kg; 6 mg/kg) plus pertuzumab (loading dose 840 mg; 420 mg) q3w concomitantly to all chemotherapy cycles. After a safety analysis showed a higher rate of dose reductions and treatment discontinuations with nP150 compared to P80, weekly dose of nP was reduced to 125 mg/m 2 . Results: nP was given for the majority of cycles at a dose of 150 mg/m 2 to 179 patients and at a dose of 125 mg/m 2 to 426 patients. Treatment characteristics were fairly balanced between these two sequential cohorts as well as compared to 601 patients receiving P80 except for HER2 status (HER2-positive: nP150 22%, nP125 37% and P80 33%) and Ki67 ( 2 with nP150, 119 mg/m 2 with nP125 and 78 mg/m 2 with P80, respectively. Peripheral sensory neuropathy (PNP) grade 3/4 (NCI-CTCAE v4.0) was observed in 15% with nP150, 8% with nP125 and 3% with P80, respectively. pCR was 32% with nP150, 41% with nP125 and 29% with P80 in all patients and 46% with nP150, 49% with nP125 and 26% with P80 in 277 patients with triple-negative breast cancer, respectively. Conclusions: Risk-benefit ratio of nP125 was improved over nP150 with better drug adherence and RTDI, lower frequency of PNP but a higher pCR rate. It should therefore be considered as the preferred schedule when nP is used as neoadjuvant treatment for primary breast cancer. The trial was financially supported by Celgene and Roche. Citation Format: von Minckwitz G, Untch M, Jakisch C, Schneeweiss A, Conrad B, Aktas B, Denkert C, Eidtmann H, Weibringhaus H, Kummel S, Hilfrich J, Warm M, Paepke S, Just M, Hanusch C, Hackmann J, Blohmer J-U, Clemens M, Costa SD, Gerber B, Nekljudova V, Loibl S. nab-paclitaxel at a dose of 125 mg/m 2 weekly is more efficacious but less toxic than at 150 mg/m 2 . Results from the neoadjuvant randomized GeparSepto study (GBG 69). [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 P1-14-11.

Background: Zoledronic acid (ZOL) plus adjuvant endocrine therapy significantly improved disease-free survival (DFS) at 48-and 62-month follow-up in the ABCSG-12 trial. We present efficacy results of a final additional analysis after 94.4 months.Patients and methods: Patients were premenopausal women who had undergone primary surgery for stage I/II estrogen-receptor-positive and/or progesterone-receptor-positive breast cancer with < 10 positive lymph nodes, and were scheduled for standard goserelin therapy. All 1803 patients received goserelin (3.6 mg every 28 days) and were randomized to tamoxifen (20 mg/days) or anastrozole (1 mg/days), both with or without ZOL (4 mg every 6 months) for 3 years. The primary end point was DFS; recurrence-free survival and overall survival (OS) were secondary end points.Results: After 94.4-month median follow-up (range, 0-114 months), relative risks of disease progression [hazard ratio (HR) = 0.77; 95% confidence interval (CI) 0.60-0.99; P = 0.042] and of death (HR = 0.66; 95% CI 0.43-1.02; P = 0.064) are still reduced by ZOL although no longer significant at the predefined significance level. Overall, 251 DFS events and 86 deaths were reported. Absolute risk reductions with ZOL were 3.4% for DFS and 2.2% for OS. There was no DFS difference between tamoxifen alone versus anastrozole alone, but there was a pronounced higher risk of death for anastrozole-treated patients (HR = 1.63; 95% CI 1.05-1.45; P = 0.030). Treatments were generally well tolerated, with no reports of renal failure or osteonecrosis of the jaw.Conclusion: These final results from ABCSG 12 suggest that twice-yearly ZOL enhances the efficacy of adjuvant endocrine treatment, and this benefit is maintained long-term.

Studien zur Bewertung von Bevacizumab (BEV) bei Patientinnen mit Mammakarzinom haben unterschiedliche Auswirkungen auf das progressionsfreie Überleben und das Gesamtüberleben gezeigt, was darauf hindeutet, dass ein Teil der Patienten von dieser Behandlung profitieren könnte. Leider existieren bisher keine Biomarker, um diese Patienten zu identifizieren. In der folgenden Studie untersuchten wir, ob Einzel-Nukleotid-Polymorphismen (SNPs) in Genen der VEGF-Signalkaskade mit der Rate an pathologischen Komplettremissionen (pCR) in der neoadjuvanten GeparQuinto Studie korrelieren.

Background: Anthracycline/taxane based regimen are standard of care for neoadjuvant therapy in breast cancer. A reverse sequence of taxanes followed by anthracyclines was suggested to achieve higher pCR rates (H.Earl, Lancet Oncol 2014). Dual HER2 blockade was shown to be superior to trastuzumab alone increasing the pCR rate by 20%. Nab-paclitaxel (nP) is a solvent-free formulation of paclitaxel (P) encapsulated in albumin which might further improve the pCR rate in breast cancer patients receiving neoadjuvant treatment and cause lower toxicity. Methods: In the GeparSepto study (NCT01583426) patients were randomized to either nP (125 mg/m 2 ) q1w or P (80mg/m 2 ) q1w for 12 weeks followed by 4 cycles of conventionally dosed EC (E, epirubicin 90mg/m 2 ; C, cyclophosphamide 600 mg/m 2 ) q3w. The primary objective is to compare the pathological complete response rate (pCR, ypT0 ypN0). Further objectives are to compare the pCR rate in predefined subgroups, pCR by other definitions, clinical response rate, rate of breast conserving surgery and toxicity and compliance. Patients with untreated, histologically confirmed uni- or bilateral, cT2- cT4d carcinoma, and no clinically relevant cardiovascular and other co-morbidities were included. HER2+ patients received trastuzumab (loading dose 8mg/kg; 6 mg/kg) plus pertuzumab (loading dose 840 mg; 420 mg) q3w concomitantly. HER2, estrogen receptor, progesterone receptor, Ki67 and SPARC status were centrally assessed prior to randomization for stratification. To increase the pCR rate from 33% with P to 41% with nP, corresponding to an odds ratio of 1.41 with an alpha of 0.05 and a power of 80%, 1200 patients would be needed. A window-of opportunity study was integrated to investigate response to anti-HER2 treatment without chemotherapy, HER2+ patients were randomized to receive 6 weeks of either trastuzumab, pertuzumab or the combination with biomaterial collection at the start and the end of the window. Results: A total of 1204/1229 (window study n=71) recruited patients (7/2012 - 12/2013) from 69 German centers were evaluable, 606 receiving nP. Baseline characteristics are well balanced; median age was 49/50 years (P/nP), 33/33% of the patients presented with HER2+ tumors, 23/23% triple negative breast cancer TNBC (ER and PR 20% 69/69%; SPARC positive 15.7/16%. 265 patients reported SAEs (119 P/146 nP) and 4 died on study (1 P: cardiac decompensation; 3 nP: accident at home, multiorgan failure, sepsis during EC). The pCR rate (ypT0 ypN0) is 29% with P and 38% with nP, OR 1.5; p Conclusions: GeparSepto showed that the pCR rate is significantly higher with nab-paclitaxel compared to solvent-based paclitaxel given weekly before anthracycline based chemotherapy. Subgroupanalyses and 2ndary endpoints will be presented at the meeting. The trial was financially supported by Roche and Celgene. The window-substudy was funded within the EU-FP7 project RESPONSIFY No 278659. Citation Format: Michael Untch, Christian Jackisch, Andreas Schneeweis, Bettina Conrad, Bahriye Aktas, Carsten Denkert, Holger Eidtmann, Hermann Wiebringhaus, Sherko Kummel, Jorn Hilfrich, Mathias Warm, Stefan Paepke, Marianne Just, Claus Hanusch, John Hackmann, Jens-Uwe Blohmer, Michael Clemens, Serban Dan Costa, Bernd Gerber, Valentina Nekljudova, Sibylle Loibl, Gunter von Minckwitz. A randomized phase III trial comparing neoadjuvant chemotherapy with weekly nanoparticle-based paclitaxel with solvent-based paclitaxel followed by anthracyline/cyclophosphamide for patients with early breast cancer (GeparSepto); GBG 69 [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr S2-07.

BACKGROUND:Assessment of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) might be an important tool in identifying human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients unlikely to derive benefit from anti-HER2 therapies. However, studies to date have failed to demonstrate its predictive role in any treatment setting.PATIENTS AND METHODS:Prospectively collected baseline core biopsies from 429 early-stage HER2-positive breast cancer patients treated with trastuzumab, lapatinib, or their combination in the Neo-ALTTO study were stained using two anti-PTEN monoclonal antibodies (CST and DAKO). The association of PTEN status and PI3K pathway activation (defined as either PTEN loss and/or PIK3CA mutation) with total pathological complete response (tpCR) at surgery, event-free survival (EFS), and overall survival (OS) was evaluated.RESULTS:PTEN loss was observed in 27% and 29% of patients (all arms, n = 361 and n = 363) for CST and DAKO, respectively. PTEN loss was more frequently observed in hormone receptor (HR)-negative (33% and 36% with CST and DAKO, respectively) compared with HR-positive tumours (20% and 22% with CST and DAKO, respectively). No significant differences in tpCR rates were observed according to PTEN status. PI3K pathway activation was found in 47% and 48% of patients (all arms, n = 302 and n = 301) for CST and DAKO, respectively. Similarly, tpCR rates were not significantly different for those with or without PI3K pathway activation. Neither PTEN status nor PI3K pathway activation were predictive of tpCR, EFS, or OS, independently of treatment arm or HR status. High inter-antibody and inter-observer agreements were found (>90%). Modification of scoring variables significantly affected the correlation between PTEN and HR status but not with tpCR.CONCLUSION:These data show that PTEN status determination is not a useful biomarker to predict resistance to trastuzumab and lapatinib-based therapies. The lack of standardization of PTEN status determination may influence correlations between expression and relevant clinical end points.CLINICAL TRIALS:This trial is registered with ClinicalTrials.gov: NCT00553358.

BACKGROUND:The GeparQuattro study showed that adding capecitabine or prolonging the duration of anthracycline-taxane-based neoadjuvant chemotherapy from 24 to 36 weeks did not increase pathological complete response (pCR) rates. Trastuzumab-treated patients with HER2-positive disease showed a higher pCR rate than patients with HER2-negative disease treated with chemotherapy alone. We here present disease-free (DFS) and overall survival (OS) analyses.PATIENTS AND METHODS:Patients (n = 1495) with cT ≥ 3 tumors, or negative hormone-receptor status, or positive hormone-receptor and clinically node-positive disease received four times epirubicin/cyclophosphamide and were thereafter randomly assigned to four times docetaxel (Taxotere), or four times docetaxel/capecitabine over 24 weeks, or four times docetaxel followed by capecitabine over 36 weeks. Patients with HER2-positive tumors received 1 year of trastuzumab, starting with the first chemotherapy cycle. Follow-up was available for a median of 5.4 years.RESULTS:Outcome was not improved for patients receiving capecitabine (HR 0.92; P = 0.463 for DFS and HR 93; P = 0.618 for OS) as well as for patients receiving 36 weeks of chemotherapy (HR 0.97; P = 0.818 for DFS and HR 0.97; P = 0.825 for OS). Trastuzumab-treated patients with HER2-positive disease showed similar DFS (P = 0.305) but a significantly better adjusted OS (P = 0.040) when compared with patients with HER2-negative disease treated with chemotherapy alone. Recorded long-term cardiac toxicity was low.CONCLUSIONS:Long-term results, similar to the results of pCR, do not support the use of capecitabine in the neoadjuvant setting in addition to an anthracycline-taxane-based chemotherapy. However, the results support previous data showing a benefit of trastuzumab as predicted by higher pCR rates.

BACKGROUND:The GeparQuinto study showed that adding bevacizumab to 24 weeks of anthracycline-taxane-based neoadjuvant chemotherapy increases pathological complete response (pCR) rates overall and specifically in patients with triple-negative breast cancer (TNBC). No difference in pCR rate was observed for adding everolimus to paclitaxel in nonearly responding patients. Here, we present disease-free (DFS) and overall survival (OS) analyses.PATIENTS AND METHODS:Patients (n = 1948) with HER2-negative tumors of a median tumor size of 4 cm were randomly assigned to neoadjuvant treatment with epirubicin/cyclophosphamide followed by docetaxel (EC-T) with or without eight infusions of bevacizumab every 3 weeks before surgery. Patients without clinical response to EC ± Bevacizumab were randomized to 12 weekly cycles paclitaxel with or without everolimus 5 mg/day. To detect a hazard ratio (HR) of 0.75 (α = 0.05, β = 0.8) 379 events had to be observed in the bevacizumab arms.RESULTS:With a median follow-up of 3.8 years, 3-year DFS was 80.8% and 3-year OS was 89.7%. Outcome was not different for patients receiving bevacizumab (HR 1.03; P = 0.784 for DFS and HR 0.974; P = 0.842 for OS) compared with patients receiving chemotherapy alone. Patients with TNBC similarly showed no improvement in DFS (HR = 0.99; P = 0.941) and OS (HR = 1.02; P = 0.891) when treated with bevacizumab. No other predefined subgroup (HR+/HER2-; locally advanced (cT4 or cN3) or not; cT1-3 or cT4; pCR or not) showed a significant benefit. No difference in DFS (HR 0.997; P = 0.987) and OS (HR 1.11; P = 0.658) was observed for nonearly responding patients receiving paclitaxel with or without everolimus overall as well as in subgroups.CONCLUSIONS:Long-term results, in opposite to the results of pCR, do not support the neoadjuvant use of bevacizumab in addition to an anthracycline-taxane-based chemotherapy or everolimus in addition to paclitaxel for nonearly responding patients.CLINICAL TRIAL NUMBER:NCT 00567554, www.clinicaltrials.gov.

Aim: Neoadjuvant chemotherapy uses anthracycline/taxane based combinations of ≥18 weeks as standard treatment. Concurrent administration of trastuzumab in HER2+ disease achieves a pCR rate (ypT0 ypN0) of approx. 40%. Dual anti-HER2 blockade can increase the rate by another 20%. DAFNE (NCT015591477) investigates the combination of afatinib (BIBW 2992), an irreversible ErbB-family blocker with trastuzumab.

BACKGROUND:We evaluated the pathological complete response (pCR) rate after neoadjuvant epirubicin, (E) cyclophosphamide (C) and docetaxel containing chemotherapy with and without the addition of bevacizumab in patients with triple-negative breast cancer (TNBC).PATIENTS AND METHODS:Patients with untreated cT1c-4d TNBC represented a stratified subset of the 1948 participants of the HER2-negative part of the GeparQuinto trial. Patients were randomized to receive four cycles EC (90/600 mg/m(2); q3w) followed by four cycles docetaxel (100 mg/m(2); q3w) each with or without bevacizumab (15 mg/kg; q3w) added to chemotherapy.RESULTS:TNBC patients were randomized to chemotherapy without (n = 340) or with bevacizumab (n = 323). pCR (ypT0 ypN0, primary end point) rates were 27.9% without and 39.3% with bevacizumab (P = 0.003). According to other pCR definitions, the addition of bevacizumab increased the pCR rate from 30.9% to 41.8% (ypT0 ypN0/+; P = 0.004), 36.2% to 46.4% (ypT0/is ypN0/+; P = 0.009) and 32.9% to 43.3% (ypT0/is ypN0; P = 0.007). Bevacizumab treatment [OR 1.73, 95% confidence interval (CI) 1.23-2.42; P = 0.002], lower tumor stage (OR 2.38, 95% CI 1.24-4.54; P = 0.009) and grade 3 tumors (OR 1.68, 95% CI 1.14-2.48; P = 0.009) were confirmed as independent predictors of higher pCR in multivariate logistic regression analysis.CONCLUSIONS:The addition of bevacizumab to chemotherapy in TNBC significantly increases pCR rates.

Abstract Introduction Assessment of PTEN might be an important tool in identifying patients unlikely to derive substantial benefit from trastuzumab and lapatinib-based therapies. Current studies failed to demonstrate an unequivocal predictive role of PTEN in human epidermal growth factor receptor-2 (HER2)-positive breast cancer both in neo-adjuvant and adjuvant settings. Lack of standardization of PTEN status determination in formalin fixed paraffin embedded (FFPE) tissue samples together with the small datasets analyzed in previous studies may have contributed to conflicting PTEN results and high variability of PTEN loss rates reported (22%-64%). Methods In the present study we have conducted a preliminary analysis investigating the influence of the antibodies, scoring methods and cutoff criteria used, together with the impact of inter-observer variability on PTEN status determination. Core biopsies from 429 FFPE baseline samples from early-stage HER2-positive breast cancer patients prospectively collected in the neoALTTO trial were stained with two widely used anti-PTEN monoclonal antibodies (clone 6H2.1 from DAKO and clone 138G6 from Cell Signaling Technology-CST). Two different pathologists independently scored the slides using the H-score system. Two different cut-off criteria were used to define PTEN loss of expression: H-score < 50 and ≤10% positive staining (any level of intensity). Results Out of 429 processed samples, 363 and 369 were evaluable for observer 1 (CST and DAKO, respectively) and 367 were evaluable for observer 2, with an average missing rate of 15%. A strong linear correlation was observed between CST and DAKO antibodies for both observers (R2 > 0.7). After setting a cutoff for PTEN loss, the observed discordance rate was below 10%, with the number of discordant cases ranging from 28 to 33 (depending on the cut-off criteria and observer). Inter-observer correlation was strong with both antibodies (R2 = 0.8). Based on the cutoff criteria and antibodies used, inter-observer discordance rates ranged between 6% and 10%; the lowest rate observed at ≤10% cutoff threshold with CST antibody. PTEN was classified as “loss” in 23%, 19%, 16%, and 13% of cases by observer 1 and in 32%, 29%, 24%, 19% of cases by observer 2 using DAKO H-score<50, CST H-score<50, DAKO≤10%, and CST≤10% criteria, respectively. Conclusion Our preliminary analysis showed high inter-antibody and inter-observer concordant rates for PTEN status determination by IHC. However, the lack of a standardized definition of PTEN cutoff thresholds for defining negativity and positivity generated loss call rates ranging from 13% to 32% within the same dataset. Correlative analyses with pCR and PIK3CA status are ongoing to determine the impact of PTEN expression and its variability in predicting response to single-agent or dual HER2 targeting. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD1-7.