Abstract P1-14-11: 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)
Authors: 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 
Published: May 2016

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 (&lt;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.