Nab-Paclitaxel pCR Results May Support Use In Primary Invasive Breast Cancer

Neoadjuvant nab-paclitaxel is non-inferior to solvent-based paclitaxel for pathological complete response in women with treatment-naive invasive breast cancer

medwireNews: The pathological complete response (pCR) rate is higher in women with primary invasive breast cancer who receive neoadjuvant nanoparticle albumin-bound (nab)-paclitaxel than those given the solvent-based form of the taxane, phase III trial results suggest.

Non-inferiority of nab-paclitaxel for this primary endpoint was reached, with 38% of the 606 treatment-naive patients randomly assigned to receive 12 weeks of nab-paclitaxel achieving pCR compared with 29% of the 600 patients given solvent-based paclitaxel, giving a significant unadjusted odds ratio (OR) of 1.53.

And nab-paclitaxel remained an independent predictor of pCR after adjusting for confounding factors such as age, and tumour nodal status and histology, with an OR of 1.66.

The investigators caution in The Lancet Oncology that until survival data mature, it is unknown whether this pCR benefit will translate to an improvement in disease-free survival.

Nevertheless, they comment: “This finding, and the fact that the new checkpoint inhibitors currently being tested in breast cancer will be given with nab-paclitaxel (because it can be given without steroids), could lead to an exchange of the preferred taxane in primary breast cancer therapy.”

Subgroup analysis showed that the benefit of nab-paclitaxel was not significant for the patients who had hormone receptor-positive, HER2-negative disease, making up approximately half the population.

However, patients with triple-negative breast cancer gained a “particular benefit” with nab-paclitaxel, with a pCR achieved by 48% of 139 patients versus 26% of 137 patients given solvent-based paclitaxel, a significant difference.

“The results in triple-negative breast cancer support the use of nab-paclitaxel as a partner and backbone therapy for many new agents (eg, checkpoint inhibitors, PARP inhibitors)”, say Sibylle Loibl, from the German Breast Group in Neu-Isenburg, and co-authors.

The patients were given nab-paclitaxel 150 mg/m2 or solvent-based paclitaxel 80 mg/m2 for 12 weeks on days 1, 8 and 15 of a 3-week cycle. The nab-paclitaxel dose was reduced to 125 mg/m2 by the independent data monitoring committee after 464 patients had been recruited, when analysis showed nab-paclitaxel-treated patients had higher rates of discontinuation and sensory neuropathy.

Taxane treatment was followed by epirubicin plus cyclophosphamide, and the 396 HER2-positive patients also received trastuzumab and pertuzumab concurrently, and trastuzumab for 1 year after surgery.

Nab-paclitaxel was associated with a higher rate of adverse events than solvent-based paclitaxel, with 26% and 21% of patients experiencing at least one serious adverse event, respectively.

In particular, nab-paclitaxel-treated patients had higher rates of grade 3 or 4 anaemia than those given solvent-based paclitaxel, as well as all-grade neutropenia, although rates of grade 3 or 4 neutropenia and febrile neutropenia were comparable.

Peripheral sensory neuropathy was more common with nab-paclitaxel for all time points and grades, and grade 2–4 symptoms took a longer time resolve. Grade 3 and 4 peripheral sensory neuropathy events reduced from 15% to 8% following the dose amendment and this compared with 3% in the solvent-based paclitaxel group.

Taxane dose reduction was required significantly more often by the nab-paclitaxel patients than the solvent-based paclitaxel group (30 vs 12%).

In a linked comment, Marco Colleoni, from the European Institute of Oncology in Milan, Italy, emphasizes the need to determine the long-term impact of peripheral sensory neuropathy with nab-paclitaxel, acknowledging that associated neurotoxicity may continue for up to 3 years after treatment.

“The results of the present study are important and helpful for the design of new treatment strategies including nab-paclitaxel, especially for tailored investigations in selected subtypes, such as triple negative disease”, he concludes.

“Meanwhile, results from ongoing studies with a similar design (eg, the ETNA trial [NCT01822314]), as well as survival data, are required before any modification of current clinical practice can be made.”

References

Untch M, Jackisch C, Schneeweiss A, et al. Nab-paclitaxel versus solvent-based paclitaxel in neoadjuvant chemotherapy for early breast cancer (GerparSepto–GBG 69): a randomised, phase 3 trial. Lancet Oncol 2016; Advance online publication 8 February. DOI: http://dx.doi.org/10.1016/S1470-2045(15)00542-2

Colleoni M. Neoadjuvant nab-paclitaxel in breast cancer: trial results and patient care. Lancet Oncol 2016; Advance online publication 8 February. DOI: http://dx.doi.org/10.1016/S1470-2045(15)00566-5

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