Abstract S2-07: 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
Authors: Untch Michael , Jackisch Christian , Schneeweiß Andreas , Conrad Bettina , Aktas Bahriye , Denkert Carsten , Eidtmann Holger , Wiebringhaus Hermann , Kümmel Sherko , Hilfrich Jörn , Warm Mathias , Paepke Stefan , Just Marianne , Hanusch Claus , Hackmann John , Blohmer Jens-Uwe , Clemens Michael , Costa Serban Dan , Gerber Bernd , Nekljudova Valentina , Loibl Sibylle , von Minckwitz Gunter 
Published: May 2015

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/m2) q1w or P (80mg/m2) q1w for 12 weeks followed by 4 cycles of conventionally dosed EC (E, epirubicin 90mg/m2; C, cyclophosphamide 600 mg/m2) 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 &lt;1 %), 87/85% ductal invasive, 56/52% G3 tumors; Ki67&gt;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&lt;0.01.

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 Schneeweiß, Bettina Conrad, Bahriye Aktas, Carsten Denkert, Holger Eidtmann, Hermann Wiebringhaus, Sherko Kümmel, Jörn 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.