Emerging Albumin-Binding Anticancer Drugs for Tumor-Targeted Drug Delivery: Current Understandings and Clinical Translation

Albumin has shown remarkable promise as a natural drug carrier by improving pharmacokinetic (PK) profiles of anticancer drugs for tumor-targeted delivery. The exogenous or endogenous albumin enhances the circulatory half-lives of anticancer drugs and passively target the tumors by the enhanced permeability and retention (EPR) effect. Thus, the albumin-based drug delivery leads to a potent antitumor efficacy in various preclinical models, and several candidates have been evaluated clinically. The most successful example is Abraxane, an exogenous human serum albumin (HSA)-bound paclitaxel formulation approved by the FDA and used to treat locally advanced or metastatic tumors. However, additional clinical translation of exogenous albumin formulations has not been approved to date because of their unexpectedly low delivery efficiency, which can increase the risk of systemic toxicity. To overcome these limitations, several prodrugs binding endogenous albumin covalently have been investigated owing to distinct advantages for a safe and more effective drug delivery. In this review, we give account of the different albumin-based drug delivery systems, from laboratory investigations to clinical applications, and their potential challenges, and the outlook for clinical translation is discussed. In addition, recent advances and progress of albumin-binding drugs to move more closely to the clinical settings are outlined.

Retrospective comparisons of nanoparticle albumin-bound paclitaxel and docetaxel neoadjuvant regimens for breast cancer

Aim: To compare the efficacy and safety of 2-weekly nanoparticle albumin-bound paclitaxel (nP) and 3-weekly docetaxel regimens as neoadjuvant systemic therapy (NST) for breast cancer. Materials & methods: Patients (n = 201) received NST comprising either dose-dense epirubicin and cyclophosphamide followed by 2-weekly nP (n = 104) or 3-weekly courses of epirubicin and cyclophosphamide followed by docetaxel (n = 97). Results: Higher pathological complete response rates were achieved by the nP group. Subgroup analysis showed that the nP-based regimen achieved higher pathological complete response rates in patients with triple-negative tumor cells and high Ki67 levels. However, grades 3-4 peripheral sensory neuropathies were more frequent in the nP group. Conclusion: The 2-weekly nP-based regimen might be a better choice of NST for patients with breast cancer.

Clinical outcomes of neoadjuvant chemotherapy for patients with breast cancer: Tri-weekly nanoparticle albumin-bound paclitaxel followed by 5-fluorouracil, epirubicin, and cyclophosphamide: a retrospective observational study

Neoadjuvant chemotherapy (NAC) using the combination of anthracycline and taxanes is the standard regimen for patients with primary breast cancer. Among the taxanes, conventional paclitaxel (PTX) and docetaxel have usually been adopted in the neoadjuvant or adjuvant setting. Nanoparticle albumin-bound paclitaxel (nab-PTX) is a solvent-free formulation that can be delivered to cancer cells at higher doses than conventional PTX. This study is a retrospective observational study in a single institution. We evaluated the efficacy and safety of nab-PTX followed by 5-fluorouracil, epirubicin, and cyclophosphamide (FEC) in the neoadjuvant setting. In this study, 50 patients with primary breast cancer received nab-PTX (q3w, 260 mg/m² ± trastuzumab 6 mg/kg) followed by FEC (q3w, 5-fluorouracil 500 mg/m², epirubicin 100 mg/m², and cyclophosphamide 500 mg/m²) prior to surgery. The efficacy was evaluated using the clinical response rate (CRR), pathological complete response (pCR) rate, and Ki67 labeling index. Safety was evaluated using the frequency of treatment-related adverse events and relative dose intensity (RDI). All patients received at least one course of chemotherapy. The CRR and pCR rate were 88.0% and 40.0%, respectively. The mean Ki67 labeling index was significantly decreased from 47.7% to 24.6% after NAC. The safety profiles were comparable with previously reported regimens, and high RDIs were obtained (97.2% for nab-PTX and 95.5% for FEC). This study illustrated the efficacy and tolerability of a neoadjuvant regimen of nab-PTX followed by FEC.

Efficacy and safety of nanoparticle albumin-bound paclitaxel as neoadjuvant chemotherapy in HER2-negative breast cancer

CONTEXT

Nanoparticle albumin-bound paclitaxel (Nab-PTX) is a form of paclitaxel bound to albumin nanoparticles and is used widely in a neoadjuvant setting for patients with breast cancer.

AIMS

We conducted a retrospective study to compare the efficacy and safety of Nab-PTX to PTX as neoadjuvant chemotherapy for patients with operable HER2-negative breast cancer.

SETTINGS AND DESIGN

In total, 50 patients were enrolled. Nab-PTX was administered in the study group, and PTX was administered in the control group.

SUBJECTS AND METHODS

The clinical response and safety profile were recorded. The expression of secreted protein acidic rich in cysteine (SPARC) in tumor tissue was examined.

STATISTICAL ANALYSIS

The efficacy and safety analyses were computed using SPSS statistical software. Multiple logistic regression analysis was performed to evaluate the exploratory variables (age, stage, estrogen receptor, partial response, and SPARC expression) for the pathological complete response (pCR), and Fisher's exact test was performed to evaluate the relationship between SPARC and pCR.

RESULTS

Both groups of patients achieved a good clinical response. The pCR rate for the Nab-PTX regimen was significantly higher than that for the PTX regimen. The most common adverse events were neutropenia, peripheral sensory neuropathy, arthralgia, and myalgia. In 68% of cases in the Nab-PTX group, high SPARC expression was observed.

CONCLUSIONS

As neoadjuvant therapy, the Nab-PTX regimen has advantages over conventional taxane regimen in patients with HER2-negative breast cancer. With this regimen, a high pCR rate was achieved with a good safety profile.

Leptomeningeal Carcinomatosis in a Patient with Pancreatic Cancer Responding to Nab-Paclitaxel plus Gemcitabine

Leptomeningeal carcinomatosis is an extremely rare, but devastating complication in pancreatic cancer patients with a poor prognosis despite multimodal treatment. We present a 51-year-old male patient with the very rare condition of leptomeningeal carcinomatosis originating from pancreatic cancer. He presented to our hospital with severe headache and neck stiffness 30 months after systemic chemotherapy. Cerebral and spinal MRI as well as cerebrospinal fluid examination confirmed the diagnosis of leptomeningeal carcinomatosis. The patient responded to gemcitabine plus nab-paclitaxel in terms of elimination of tumor cells from the CSF and concurrent clinical improvement for 3 months. The observed findings suggest that the combination of gemcitabine plus nab-paclitaxel is potentially effective in affected cerebrospinal fluid of pancreatic carcinoma patients.

Efficacy of two-weekly nanoparticle albumin-bound paclitaxel as neoadjuvant chemotherapy for breast cancer

Aim: Compare the two-weekly regimens of nanoparticle albumin-bound paclitaxel (nab-P) with solvent-based paclitaxel (sb-P) as neoadjuvant chemotherapy for breast cancer. Materials & methods: Patients (n = 162) with operable early breast cancer received four cycles of dose-dense epirubicin and cyclophosphamide followed by four two-weekly cycles of nab-P (n = 83) or sb-P (n = 79), with trastuzumab when needed. Results: Across all the patients, the ypT0 ypN0 and ypT0/is ypN0 pathological complete response rates in the nab-P group were not superior to those in the sb-P group. However, pathological complete response rates for triple-negative breast cancer were significantly better with nab-P than with sb-P. Meanwhile, nab-P also induced more peripheral sensory neuropathy. Conclusion: The two-weekly nab-P regimen is a good neoadjuvant chemotherapy choice for triple-negative breast cancer.

Tailored NEOadjuvant epirubicin, cyclophosphamide and Nanoparticle Albumin-Bound paclitaxel for breast cancer: The phase II NEONAB trial-Clinical outcomes and molecular determinants of response

BACKGROUND

This study evaluated the feasibility of achieving high response rates in stage II or III breast cancer by tailoring neoadjuvant therapy using clinical and histopathological features and the Oncotype DX Breast Recurrence Score. Genomic determinants of response and resistance were also explored.

PATIENTS AND OUTCOME MEASURES

Fifty-one patients were enrolled. The primary cohort comprised 40 patients: 15 human epidermal growth factor receptor type 2 (HER2)-amplified; 15 triple-negative (TNBC); and ten hormone receptor (HR)-positive, HER2-non-amplified tumours; with recurrence scores ≥25. Patients were treated with epirubicin and cyclophosphamide, followed by nab-paclitaxel, with the addition of trastuzumab if HER2-amplified. The primary endpoint was pathological complete response (pCR) in the breast. Pre- and post-treatment tumour samples underwent variant burden, gene and gene pathway, mutational signature profile and clonal evolution analyses.

RESULTS

The pCR rates were: overall 55% (n = 22), HER2-amplified 80% (n = 12), triple-negative 46% (n = 7) and HR-positive, HER2-non-amplified 30% (n = 3). Grade 3 or 4 adverse events included febrile neutropenia (8%), neutropenia (18%), sensory neuropathy (5%), deranged transaminases (5%), fatigue (2%), diarrhoea (2%), and pneumothorax (2%). Molecular analyses demonstrated strong similarities between residual disease and matched primary tumour. ATM signalling pathway alterations and the presence of a COSMIC Signature 3 implied the majority of tumours contained some form of homologous repair deficiency. ATM pathway alterations were identified in the subset of TNBC patients who did not achieve pCR; Signature 3 was present in both pCR and non-pCR subgroups. Clonal evolution analyses demonstrated both persistence and emergence of chemoresistant clones.

CONCLUSIONS

This treatment regime resulted in a high rate of pCR, demonstrating that tailored neoadjuvant therapy using a genomic recurrence score is feasible and warrants further investigation. Molecular analysis revealed few commonalities between patients. For TNBC future clinical gains will require precision medicine, potentially using DNA sequencing to identify specific targets for individuals with resistant disease.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01830244.

Combined Targeted Therapies for First-line Treatment of Metastatic Triple Negative Breast Cancer-A Phase II Trial of Weekly Nab-Paclitaxel and Bevacizumab Followed by Maintenance Targeted Therapy With Bevacizumab and Erlotinib

INTRODUCTION

Angiogenesis and epidermal growth factor receptor signaling are potential therapeutic targets in triple negative breast cancer (TNBC). We hypothesized that targeting these critical pathways would prolong progression-free survival with first-line therapy for metastatic TNBC.

PATIENTS AND METHODS

We conducted a phase II trial of nab-paclitaxel and bevacizumab, followed by maintenance therapy with bevacizumab and erlotinib, for patients with metastatic TNBC. During induction, the patients received nab-paclitaxel 100 mg/m² intravenously (days 1, 8, and 15) and bevacizumab 10 mg/kg intravenously (days 1 and 15) every 28 days for 6 cycles. Patients free of progression at 24 weeks received maintenance therapy with bevacizumab 10 mg/kg intravenously every 2 weeks and oral erlotinib 150 mg/d until disease progression. The primary endpoint was progression-free survival (PFS). The secondary endpoints were best overall response, overall survival (OS), and adverse events. We explored the measurement of circulating tumor cells as a prognostic marker.

RESULTS

A total of 55 evaluable patients were enrolled. The median PFS and OS for the cohort was 9.1 months (95% confidence interval, 7.2-11.1) and 18.1 months (95% confidence interval, 15.6-21.7), respectively. Of the 53 patients with measurable disease, 39 (74%) had experienced a partial response and 10 (19%) had stable disease using the Response Evaluation Criteria In Solid Tumors. The most common toxicities were uncomplicated neutropenia, fatigue, and neuropathy. Decreased circulating tumor cells from baseline to the first assessment correlated with longer PFS and OS.

CONCLUSION

Nab-paclitaxel and bevacizumab, followed by maintenance targeted therapy with bevacizumab and erlotinib, resulted in PFS similar to that of other trials. Most patients experienced a partial response (74%). Most patients received maintenance therapy (55%), providing a break from cytotoxic chemotherapy.

Phase II study of neoadjuvant anthracycline combined with nanoparticle albumin-bound paclitaxel for human epidermal growth factor receptor 2-negative breast cancer

Neoadjuvant chemotherapy (NAC) with anthracyclines followed by taxane chemotherapy has become the standard treatment for patients with locally advanced, operable breast cancer. Recently, the efficacy of nanoparticle albumin-bound paclitaxel (nab-PTX) for metastatic breast cancer was reported. However, there are still few studies of a neoadjuvant regimen including nab-PTX. Thus, the present phase II study evaluated the efficacy and safety of 5-fluorouracil, epirubicin and cyclophosphamide (FEC regimen) followed by nab-PTX as neoadjuvant treatment for operable human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Women with operable HER2-negative breast cancer (clinical stage T1a-4N1-3) received 4 cycles of FEC (5-fluorouracil 500 mg/m², epirubicin 100 mg/m² and cyclophosphamide 500 mg/m² every 21 days), followed by 4 cycles of nab-PTX at 260 mg/m² every 21 days. The patients then underwent mastectomy or breast-conserving surgery (BCS). The primary endpoint was pathological complete response (pCR) rate. The secondary endpoints included clinical response rate, pathological response rate, BCS rate and safety. A total of 16 patients were evaluated and 3 patients (18%) achieved pCR (1 patient with estrogen receptor-positive cancer and 2 with estrogen receptor-negative cancer). The pCR rate was 12 and 25% in patients with estrogen receptor-positive and -negative cancers, respectively. The clinical response rate was 100% (clinical complete and partial response in 6 and 10 patients, respectively). The BCS rate was 31.25%. Three patients experienced grade 3 neutropenia during FEC therapy, and no grade 3/4 events occurred during nab-PTX therapy. Thus, neoadjuvant therapy with FEC followed by nab-PTX for operable HER2-negative breast cancer was found to be a safe and effective option.

Neoadjuvant Therapy with Weekly Nanoparticle Albumin-Bound Paclitaxel for Luminal Early Breast Cancer Patients: Results from the NABRAX Study (GEICAM/2011-02), a Multicenter, Non-Randomized, Phase II Trial, with a Companion Biomarker Analysis

BACKGROUND

Nanoparticle albumin-bound paclitaxel (nab-Paclitaxel) is an alternative to standard taxanes for breast cancer (BC) treatment. We evaluated nab-Paclitaxel efficacy as neoadjuvant treatment for early estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-) disease.

MATERIALS AND METHODS

Women with ER+, HER2-, stage II-III BC were treated preoperatively with four cycles of weekly nab-Paclitaxel (150 mg/m²), 3 weeks on and 1 week off. We hypothesized that poor pathological response rate (residual cancer burden [RCB] III; Symmans criteria) would be ≤16%.

RESULTS

Eighty-one patients with a median age of 47 years were treated; 64.2% were premenopausal, and 69% of tumors were stage II. Residual cancer burden III rate was 28.4% (95% confidence interval [CI]: 18.6%-38.2%), RCB 0+I (good response) rate was 24.7% (95% CI: 15.3%-34.1%) and RCB 0 (complete response) rate was 7.4% (95% CI: 1.7%-13.1%). Objective response rate by magnetic resonance imaging was 76.5% and rate of conversion to breast conserving surgery was 40.0%. The most frequent grade 3 and 4 toxicity was neutropenia (12.3% and 3.7% of patients, respectively), without any febrile neutropenia. Sensory neuropathy grade 2 and 3 were seen in 25.9% and 2.5% of patients, respectively. Tumor secreted protein, acidic, cysteine-rich (SPARC) overexpression was significantly associated with RCB 0 (odds ratio: 0.079; 95% CI: 0.009-0.689; p = .0216).

CONCLUSION

Despite failing to confirm an RCB III rate ≤16% in nab-Paclitaxel-treated patients, the RCB 0+I rate indicates a significant drug antitumor activity with low rates of grade 3-4 toxicity. Our exploratory biomarker analysis suggests a potential predictive role of complete response for SPARC. Confirmatory analyses are warranted, adapting dose and schedule to decrease peripheral neurotoxicity. (Trial registration: European Clinical Trials Database study number: 2011-004476-10; ClinicalTrials.gov: NCT01565499).

IMPLICATIONS FOR PRACTICE

The pathological response rate (residual cancer burden [RCB]; Symmans criteria) of nanoparticle albumin-bound paclitaxel administered as neoadjuvant treatment for early estrogen receptor-positive, human epidermal growth factor receptor 2-negative disease was evaluated. Whereas poor response (RCB III) was 24.7%, similar to that for docetaxel, good response (RCB 0+I) reached 23.0%, far superior to the 13% for docetaxel, while keeping toxicity low. Exploratory biomarker analysis suggests secreted protein, acidic, cysteine-rich overexpression in tumor cells as a potential predictor of complete response (RCB 0). Findings point to an encouraging single-agent neoadjuvant treatment with low toxicity, which warrants future research and development.

Nanoparticle albumin-bound paclitaxel as neoadjuvant chemotherapy of breast cancer: a systematic review and meta-analysis

BACKGROUND

The value of nanoparticle albumin-bound paclitaxel (nab-paclitaxel) in neoadjuvant systemic therapy for breast cancer remains uncertain.

METHODS

Both electronic databases and proceedings of oncologic meetings were included in systematic literature search. Pooled rates of pathological complete response (pCR), odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using fixed-effect or random-effect model to determine the effect of neoadjuvant nab-paclitaxel.

RESULTS

Twenty-one studies with 2357 patients were included, 3 of which were randomized clinical trials. The aggregate pCR(ypT0/is ypN0) rate was 32% (95% CI 25-38%) in unselected breast cancer patients and variated in different subtypes. Within randomized clinical trials, the probability of achieving pCR was significantly higher in the nab-paclitaxel group than in the conventional taxanes group (OR = 1.383, 95%CI 1.141-1.676, p = 0.001). For non-hematological toxic effect, any grade and grade 3-4 peripheral sensory neuropathy occurred more frequently with nab-paclitaxel compared to paclitaxel (any grade, OR = 2.090, 95%CI 1.016-4.302, p = 0.045; grade3-4, OR = 3.766, 95%CI 2.324-6.100, p < 0.001). Hypersensitivity was more common with paclitaxel than nab-paclitaxel at any grade and grade 3-4.

CONCLUSION

nab-paclitaxel is an effective cytotoxic drug in neoadjuvant treatment of breast cancer, especially for aggressive tumors in terms of pCR. Exchange of nab-paclitaxel for conventional taxanes could significantly improve pCR rate with reasonable toxicities.

Preoperative neoadjuvant chemotherapy using nanoparticle albumin-bound paclitaxel followed by epirubicin and cyclophosphamide for operable breast cancer: a multicenter phase II trial

Background

Recently, the use of taxane-based regimens before anthracycline-based regimens has been shown to achieve high pathological complete response (pCR) rates in patients with breast cancer. Nanoparticle albumin-bound paclitaxel (nab-PTX) has been reported as highly effective and less toxic compared with Cremophor-based Taxol. This phase II clinical trial evaluated the safety and efficacy of preoperative neoadjuvant chemotherapy (NAC) with nab-PTX followed by an epirubicin plus cyclophosphamide (EC)-based regimen for operable breast cancer.

Patients and methods

From June 2012 to January 2014, four cycles of every-3-week (q3w) nab-PTX [plus q3w trastuzumab in cases of human epidermal growth factor 2 (HER2) positivity] followed by four cycles of q3w EC were administered to patients with operable breast cancer (stage IC–IIIA). The primary endpoint was the pCR rate (ypT0/TisypN0).

Results

A total of 55 patients were enrolled, 54 of whom received at least one nab-PTX dose. All patients underwent radical surgery after chemotherapy. The overall pCR rate was 22.2% (p = 0.006). The pCR rates for patients with the luminal B, luminal/HER2, HER2-rich, and triple-negative breast cancer subtypes were 10.5, 29.4, 60, and 15.4%, respectively. Stepwise logistic regression analysis revealed only HER2 as a significant factor for pCR (odds ratio 5.603; p = 0.024). The expression of secreted protein acidic and rich in cysteine showed no association with pCR. The clinical response rate was 70.4% (38/54), and the safety profile was tolerable.

Conclusion

Preoperative NAC with nab-PTX followed by EC is effective and safe for operable breast cancer.

Nab-paclitaxel and trastuzumab combination: a promising approach for neoadjuvant treatment in HER2-positive breast cancer

Neoadjuvant therapy is a well-established approach for the treatment of locally advanced or inflammatory breast cancer (BC) and has been increasingly used in recent years not only as a management strategy but also as a research tool. Recently, nanoparticle albumin-bound paclitaxel (nab-paclitaxel)/trastuzumab combinations have been associated with promising activity in different clinical settings. In the present case, we report a complete pathological response after neoadjuvant treatment with the trastuzumab/nab-paclitaxel combination in a locally advanced human epidermal growth factor receptor 2 (HER2)-positive BC patient, with a good toxicity profile. This combination may represent a valid therapeutic option in the neoadjuvant therapy for HER2-positive locally advanced BC.

Neoadjuvant nab-paclitaxel in the treatment of breast cancer

Neoadjuvant chemotherapy has the advantage of converting unresectable breast tumors to resectable tumors and allowing more conservative surgery in some mastectomy candidates. Chemotherapy agents, including taxanes, which are recommended in the adjuvant setting, are also considered in the neoadjuvant setting. Here, we review studies of nab-paclitaxel as a neoadjuvant treatment for patients with breast cancer. PubMed and conference or congress proceedings were searched for clinical studies of nab-paclitaxel in the neoadjuvant treatment of breast cancer. We also searched ClinicalTrials.gov for ongoing trials of nab-paclitaxel as a neoadjuvant agent in breast cancer. Twenty studies of nab-paclitaxel in the neoadjuvant setting were identified. In addition to reviewing key efficacy and safety data, we discuss how each trial assessed response, focusing on pathologic complete response and residual cancer burden scoring. Safety profiles are also reviewed. nab-Paclitaxel demonstrated antitumor activity and an acceptable safety profile in the neoadjuvant treatment of breast cancer. Ongoing and future trials will further evaluate preoperative nab-paclitaxel in breast cancer, including in combination with many novel immunological targeted therapies.

Phase II randomized clinical trial evaluating neoadjuvant chemotherapy regimens with weekly paclitaxel or eribulin followed by doxorubicin and cyclophosphamide in women with locally advanced HER2-negative breast cancer: NSABP Foundation Study FB-9

Locally advanced breast cancer (LABC) is a good setting in which to monitor response to neoadjuvant chemotherapy, to downsize the tumor (which facilitates breast-conserving surgery), and to test newer agents in untreated patients. Eribulin (E) has shown activity in patients who have undergone previous taxane, anthracycline, and capecitabine treatment. We aimed to evaluate the neoadjuvant use of E followed by doxorubicin and cyclophosphamide (AC) in patients with HER2-negative LABC, using as a control a randomized group of women who received weekly paclitaxel (WP). Fifty women with LABC were accrued January-August 2013. Patients were randomized (1:2) to receive either WP (N = 19) for 12 treatments or E (N = 31) every 3 weeks for 4 cycles followed by AC every 3 weeks for 4 cycles before surgery. 17/19 patients who took WP and 25/30 who took E completed all cycles. Patients were evaluated by clinical examination and breast MRI at baseline and after completion of E or WP. Surgical pCR in breast and lymph nodes was determined by a local pathologist following chemotherapy. Forty-nine patients received ≥1 dose of neoadjuvant chemotherapy and are included in this analysis. Forty-eight underwent surgery; one had disease that was inoperable (on E) and is included as no-pCR patient. 17/19 of these patients who took WP completed 12 doses; 28/30 on E completed 4 cycles. Six discontinued treatment on WP, E, or AC. Both treatments were well tolerated. pCR on WP = 5/19(26 %) and on E = 5/30(17 %). Both regimens were equally well tolerated with no unexpected toxicities. pCR did not suggest higher activity with E than with other standard regimens in these LABC patients.

nab-Paclitaxel dose and schedule in breast cancer

nab-Paclitaxel is approved for the treatment of metastatic breast cancer on an every-3-week schedule based on positive findings from a pivotal phase III trial in which nab-paclitaxel 260 mg/m(2) every 3 weeks was superior to solvent-based paclitaxel 175 mg/m(2) every 3 weeks for the primary endpoint of overall response rate (33 % vs 19 %; P = 0.001). Subsequently, a number of trials have examined different schedules, doses, and combinations in efforts to optimize nab-paclitaxel-based therapy for metastatic and early-stage breast cancer. The goal of this review is to evaluate the clinical experiences to date with nab-paclitaxel as a single agent or in combination with targeted agents in different treatment settings - with a focus on the feasibility of administration, adverse event profile, and standard efficacy endpoints, such as overall survival, progression-free survival, overall response rate, and pathologic complete response rate. In general, weekly dosing during the first 3 of 4 weeks appears to achieve the best clinical benefit in both the metastatic and early-stage settings. Furthermore, the data suggest that high doses of nab-paclitaxel, such as 150 mg/m(2) during first 3 of 4 weeks or 260 mg/m(2) every 2 weeks, may be more feasible and appropriate for treatment of early-stage disease compared with metastatic disease. Intense regimens of nab-paclitaxel may not be the best treatment approach for unselected patients with metastatic breast cancer, but may suit a subset of patients for whom immediate disease control is required. The growing number of nab-paclitaxel trials in breast cancer will lead to greater refinements in tailoring therapy to patients based on their individual disease and patient characteristics.

Neoadjuvant triweekly nanoparticle albumin-bound paclitaxel followed by epirubicin and cyclophosphamide for Stage II/III HER2-negative breast cancer: evaluation of efficacy and safety

OBJECTIVE

Nanoparticle albumin-bound paclitaxel (nab-PTX) is a solvent-free paclitaxel coupled to human albumin without an associated increase in toxicity. The neoadjuvant study of primary breast cancer was planned to evaluate tumor response and safety of triweekly nanoparticle albumin-bound paclitaxel.

METHODS

Patients with Stage II/III HER2-negative primary breast cancer received four courses of nanoparticle albumin-bound paclitaxel 260 mg/m(2) every 3 weeks (q3w), followed by four courses of epirubicin 90 mg/m(2) plus cyclophosphamide 600 mg/m(2) q3w. Tumor response after nanoparticle albumin-bound paclitaxel was histologically evaluated. In addition, the clinical response, breast-conserving rate and safety of this treatment were monitored.

RESULTS

Among 53 patients who received nanoparticle albumin-bound paclitaxel followed by epirubicin and cyclophosphamide neoadjuvant chemotherapy, pathological complete response and near-pathological complete response were confirmed in 3 (5.7%) and 7 (13.2%) patients who had surgery, respectively. The overall objective response rate was 71.7% after completion of chemotherapy. Based on Positron Emission Tomography Response Criteria in Solid Tumors using (18)F-fluorodeoxyglucose, complete metabolic response and partial metabolic response after 2-3 courses of nanoparticle albumin-bound paclitaxel were 15.1 and 52.8%, respectively. The most common significant toxicities of q3w nanoparticle albumin-bound paclitaxel were Grade 3 muscle pain, neuropathy and febrile neutropenia, each in 1 (1.9%) patient. There were no incidences of anaphylaxis or Grade 4/5 adverse events.

CONCLUSION

Neoadjuvant chemotherapy using q3w nanoparticle albumin-bound paclitaxel followed by epirubicin and cyclophosphamide was feasible in breast cancer patients with acceptable clinical response and drug tolerance, but conferred a low rate of pathological complete response. Monotherapy with q3w nanoparticle albumin-bound paclitaxel could be an appropriate substitute for solvent-based taxane in terms of therapeutic and safety management.

Neoadjuvant therapy for breast cancer

Neoadjuvant treatment of breast cancer refers to the use of different treatment modalities prior to surgical excision of the tumor. It has been accepted as a treatment option for patients with nonmetastatic disease, because it renders inoperable tumors operable and increases the rates of breast-conserving surgery, while achieving similar long-term clinical outcomes as adjuvant treatment. The neoadjuvant setting is being increasingly perceived as a research platform, where the biologic effects of traditional anticancer agents can be delineated, prognostic and predictive biomarkers can be identified, and the development of targeted agents can be expedited. Surrogate endpoints that can predict long-term clinical outcome and are evaluable early on, such as the pathologic complete response, offer valuable opportunities for rapid assessment of anticancer agents. Additionally, efforts for molecular profiling of the post-neoadjuvant residual disease hold the potential to lead to personalized therapy for breast cancer patients with early-stage high-risk disease.

Molecular imaging of cell death in tumors. Increasing annexin A5 size reduces contribution of phosphatidylserine-targeting function to tumor uptake

OBJECTIVE

Annexin A5 is a phosphatidylserine binding protein that binds dying cells in vivo. Annexin A5 is a potential molecular imaging agent to determine efficacy of anti-cancer therapy in patients. Its rapid clearance from circulation limits tumor uptake and, hence, its sensitivity. The aim of this study is to determine if non-invasive imaging of cell death in tumors will benefit from increasing circulation time of annexin A5 by increasing its size.

PROCEDURES

Annexin A5 size was increased by complexation of biotinylated annexin A5 with Alexa-Fluor680-labeled streptavidin. The non-binding variant of annexin A5, M1234, was used as negative control. The HT29 colon carcinoma xenograft model in NMRI nude mice was used to measure tumor uptake in vivo. Tumor uptake of fluorescent annexin A5-variants was measured using non-invasive optical imaging.

RESULTS

The annexin A5-streptavidin complex (4 ∶ 1, moles:moles, Mw ∼ 200 kDa) binds phosphatidylserine-expressing membranes with a Hill-coefficient of 5.7 ± 0.5 for Ca2+-binding and an EC50 of 0.9 ± 0.1 mM Ca2+ (EC50 is the Ca2+ concentration required for half maximal binding)(annexin A5: Hill-coefficient 3.9 ± 0.2, EC50 1.5 ± 0.2 mM Ca2+). Circulation half-life of annexin A5-streptavidin is ± 21 minutes (circulation half-life of annexin A5 is ± 4 min.). Tumor uptake of annexin A5-streptavidin was higher and persisted longer than annexin A5-uptake but depended less on phosphatidylserine binding.

CONCLUSION

Increasing annexin A5 size prolongs circulation times and increases tumor uptake, but decreases contribution of PS-targeting to tumor uptake and abolishes power to report efficacy of therapy.

Evaluating the role of nab-paclitaxel (Abraxane) in women with aggressive metastatic breast cancer

Nab-paclitaxel (Abraxane(®)) is an albumin-bound form of paclitaxel that utilizes the natural properties of albumin to improve paclitaxel delivery to the tumor. It is licensed for use in metastatic breast cancer (MBC) at a dose of 260 mg/m(2) Q3W based on its superior therapeutic index versus conventional paclitaxel 175 mg/m(2) Q3W demonstrated in a Phase III study. In a post-hoc analysis, nab-paclitaxel treatment was associated with rapid and dramatic tumor responses in patients with poor prognostic factors (visceral dominant disease, ≥3 metastatic lesions), suggesting it may be a preferred treatment for these patients. Moreover, significant efficacy has been seen with nab-paclitaxel 100 and 150 mg/m(2) QW 3/4, suggesting it may be possible to tailor use of this agent in the future.

nab-Paclitaxel in combination with biologically targeted agents for early and metastatic breast cancer

Taxanes are highly active chemotherapeutic agents used in the treatment of early-stage and metastatic breast cancer. Novel formulations have been developed to improve efficacy and decrease toxicity associated with these cytotoxic agents. nab-Paclitaxel is a biologically interactive, solvent-free, 130-nm-sized albumin-bound paclitaxel, developed to avoid the Cremophor vehicle used in solvent-based paclitaxel. Based on a pivotal phase 3 study, nab-paclitaxel was shown to be safely infused at a significantly higher dose of paclitaxel than the doses used with standard paclitaxel therapy, and had a shorter infusion time, no premedication, and higher response rates. It is now approved in the United States for treatment of breast cancer after failure of combination chemotherapy for metastatic disease or relapse within 6 months of adjuvant therapy, and has demonstrated promising efficacy and favorable tolerability. Recently, several phase 2 and 3 studies have suggested a role for nab-paclitaxel in combination with biologically targeted agents for the treatment of early- and late-stage breast cancer. This review will discuss the findings of clinical trials evaluating nab-paclitaxel in combination with biologically targeted therapeutic agents for breast cancer in the neoadjuvant, adjuvant, and metastatic settings.

Effectiveness of neoadjuvant trastuzumab and chemotherapy in HER2-overexpressing breast cancer

Purpose

Trastuzumab and chemotherapy is the current standard of care in HER2+ early or locally advanced breast cancer, but there are scanty literature data of its real world effectiveness.

Methods

We retrospectively reviewed 205 patients with HER2+ breast cancer diagnosed in 10 Italian Medical Oncology Units between July 2003 and October 2011. All patients received neoadjuvant systemic therapy (NST) with trastuzumab in association with chemotherapy. Many different chemotherapy regimens were used, even if 90 % of patients received schemes including anthracyclines and 99 % received taxanes. NST was administered for more than 21 weeks (median: 24) in 130/205 (63.4 %) patients, while trastuzumab was given for more than 12 weeks (median: 12 weeks) in 101/205 (49.3 %) patients. pCR/0 was defined as ypT0+ypN0, and pCR/is as ypT0/is+ypN0.

Results

pCR/0 was obtained in 24.8 % and pCR/is in 46.8 % of the patients. At multivariate logistic regression, nonluminal/HER2+ tumors (P < 0.0001) and more than 12 weeks of neoadjuvant trastuzumab treatment (P = 0.03) were independent predictors of pCR/0. Median disease-free survival (DFS) and cancer-specific survival (CSS) have not been reached at the time of analysis. At multivariate analysis, nonluminal/HER2+ subclass (DFS: P = 0.01 and CSS: P = 0.01) and pathological stage II–III at surgery (DFS: P < 0.0001 and CSS: P = 0.001) were the only variables significantly associated with a worse long-term outcome.

Conclusions

Our data set the relevance of molecular subclasses and residual tumor burden after neoadjuvant as the most relevant prognostic factors for survival in this cohort of patients.

HER2-targeted therapy in breast cancer: a systematic review of neoadjuvant trials

Targeting human epidermal growth factor receptor 2 (HER2) during or in sequence with chemotherapy improves overall survival in metastatic and early HER2-overexpressing breast cancer. In this paper we systematically review neoadjuvant clinical trial data in HER2-positive breast cancer and discuss key unanswered clinical questions. All trials of HER2-targeted neoadjuvant therapy were identified through non-date-limited searches of PubMED® and Biosis® and congress abstract book searches from 2000-2011. Eligible trials were prospective, had at least 10 patients and a clear definition of pathological complete response (pCR) rate. A total of 50 trials fulfilled the eligibility criteria; 41 single-arm phase II studies were identified, 37 with trastuzumab and 4 with lapatinib, with significant variability in baseline tumour characteristics and pCR rates (range 12-66.7%). Of 9 randomised phase II/III trials, 4 assessed the addition of trastuzumab to chemotherapy and a further 5 randomised trials assessed different HER2-targeting approaches. Four of these studies assessed dual HER2-targeting approaches, which universally increased pCR at the expense of increased non-cardiac toxicity when lapatinib, but not pertuzumab, was added to trastuzumab. Significant advances have been made in HER2 targeting, resulting in a marked increase in the number of breast cancer patients experiencing tumour pCR. Mature data from randomised neoadjuvant and adjuvant studies are awaited for survival outcomes with combination targeted approaches. Unanswered questions centre on the individualisation of therapy and include; which, if any, chemotherapy backbone should be used, and which patients need dual HER2 blockade?

Weekly nab-Paclitaxel in Metastatic Breast Cancer - Summary and Results of an Expert Panel Discussion

Taxanes are regarded as the most effective single agents in the treatment of metastatic breast cancer (MBC). For conventional taxanes, crucial toxicities and impairments in clinical efficacy are related to solvents necessary because of the agents' hydrophobicity. The mandatory premedication with corticosteroids causes additional side effects. Nab-paclitaxel is a solvent-free colloidal suspension of paclitaxel and human serum albumin that exploits the physiological transport properties of albumin. It is registered as monotherapy with a recommended dose of 260 mg/m(2) every 3 weeks for the treatment of patients with MBC, who have failed a first-line treatment of metastatic disease and for whom a standard anthracycline treatment is not indicated. Clinical evidence is available for the registered 3-weekly administration and for alternative weekly schedules in first and further lines of therapy of patients with MBC. During an advisory board meeting, a group of 8 German breast cancer experts reviewed the clinical data of nab-paclitaxel in MBC and discussed how nab-paclitaxel could be used in clinical practice on the basis of the current data.

Management of breast cancer with nanoparticle albumin-bound (nab)-paclitaxel combination regimens: a clinical review

BACKGROUND

Monotherapy with nanoparticle albumin-bound (nab)-paclitaxel has demonstrated improved efficacy and safety compared with solvent-based paclitaxel and docetaxel.

DESIGN

A comprehensive review of all reported studies of nab-paclitaxel combinations with other agents in all breast cancer settings was undertaken.

RESULTS

Most studies reviewed are small, phase II and non-comparative. Combinations studied included nab-paclitaxel plus trastuzumab and/or bevacizumab (with or without additional cytotoxic agents), gemcitabine, capecitabine, carboplatin, or lapatinib. The majority of metastatic and neoadjuvant studies demonstrated satisfactory efficacy and safety for nab-paclitaxel combinations, although conclusions regarding comparison with solvent-based taxane (SBT) regimens are not possible. The two adjuvant studies confirmed the safety of nab-paclitaxel combinations in this setting.

CONCLUSIONS

Although results of this review indicate that nab-paclitaxel may be an appropriate substitute for SBTs in combination regimens, additional research is required to confirm the place and cost effectiveness of these combinations before nab-paclitaxel could be recommended routinely in all settings.

Nab-paclitaxel for the treatment of breast cancer: efficacy, safety, and approval

Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) is a novel formulation of paclitaxel that does not require solvents such as polyoxyethylated castor oil and ethanol. Use of these solvents has been associated with toxic response, including hypersensitivity reactions and prolonged sensory neuropathy, as well as a negative impact in relation to the therapeutic index of paclitaxel. nab-paclitaxel displays greater antitumor activity and less toxicity than solvent-base paclitaxel. In a phase I trial of single nab-paclitaxel, the maximum tolerated dose was 300 mg/m(2) with the dose limiting toxicities being sensory neuropathy, stomatitis, and superficial keratopathy. In the metastatic setting, a pivotal comparative randomized phase III study demonstrated that nab-paclitaxel (at 260 mg/m(2) over 30 minutes infusion without premedication every 3 weeks) mediated a superior objective response rate and prolonged time to progression compared with solvent-based paclitaxel (at 175 mg/m(2) over a 3-hour injection with standard premedication). The nab-paclitaxel-treated group showed a higher incidence of sensory neuropathy than the solvent-based paclitaxel group. However, these adverse side effects rapidly resolved after interruption of treatment and dose reduction. Weekly administration of nabpaclitaxel was also more active and displayed less toxicity compared with 100 mg/m(2) docetaxel given triweekly. Nab-paclitaxel has already been approved in 42 countries for the treatment of metastatic breast cancer previously treated with anthracycline, based on confirmation of the efficacy and manageable toxicity in the metastatic setting. This review summarizes the most relevant knowledge on nab-paclitaxel for treating breast cancer in terms of clinical usefulness including efficacy and safety of this new agent.

nab-paclitaxel: a novel formulation of taxane for treatment of breast cancer

Breast cancer is the most common type of cancer diagnosed in women. Anthracyclines and taxanes are the most active and widely used chemotherapeutic agents in the treatment of both early-stage and advanced breast cancer. In the past decade, novel formulations of these cytotoxic agents have been developed to improve efficacy and decrease toxicity. nab-paclitaxel is a solvent-free, albumin-bound 130-nm particle form of paclitaxel (Abraxane, Abraxis Bioscience, CA, USA), which was developed to avoid toxicities associated with the Cremophor vehicle used in solvent-based paclitaxel. In a Phase III study, nab-paclitaxel demonstrated higher response rates, a better safety profile compared with conventional paclitaxel, and improved survival in patients receiving it as second-line therapy. Based on this pivotal trial, nab-paclitaxel is now approved in the USA for treatment of breast cancer after failure of combination chemotherapy for metastatic disease or relapse within 6 months of adjuvant therapy where prior therapy included an anthracycline unless clinically contraindicated. Recently, several Phase II studies have suggested a role for nab-paclitaxel as a single agent and in combination with other agents for first-line treatment of metastatic breast cancer. Studies are ongoing to explore the use of nab-paclitaxel in other solid tumors such as non-small-cell lung cancer, ovarian cancer and malignant melanoma.

Safety and Efficacy of nab-Paclitaxel in the Treatment of Patients with Breast Cancer

Taxanes are highly active chemotherapeutic agents in the treatment of early-stage and metastatic breast cancer. Novel formulations have been developed to improve efficacy and decrease toxicity associated with these cytotoxic agents. nab-paclitaxel is a solvent free, albumin-bound 130-nanometer particle formulation of paclitaxel (Abraxane(®), Abraxis Bioscience), which was developed to avoid toxicities of the Cremophor vehicle used in solvent-based paclitaxel. In a phase III clinical trial, nab-paclitaxel demonstrated higher response rates, better safety and side-effect profile compared to conventional paclitaxel, and improved survival in patients receiving it as second line therapy. Higher doses can be administered over a shorter infusion time without the need for special infusion sets or pre-medications. It is now approved in the US for treatment of breast cancer after failure of combination chemotherapy for metastatic disease or relapse within 6 months of adjuvant therapy, where prior therapy included an anthracycline. Recently, several phase II studies have suggested a role for nab-paclitaxel as a single agent and in combination with other agents for first-line treatment of metastatic breast cancer.

A phase II study of weekly nanoparticle albumin-bound paclitaxel with or without trastuzumab in metastatic breast cancer

INTRODUCTION

Weekly administration of nanoparticle albumin-bound (nab) paclitaxel as a first-line treatment for metastatic breast cancer (MBC) has not been fully investigated. The addition of trastuzumab, a monoclonal antibody against human epidermal growth factor receptor 2 (HER2), is less understood. This phase II study evaluated the efficacy and safety of weekly nab paclitaxel in the first-line MBC setting. Patients whose tumors overexpressed HER2 also received trastuzumab.

PATIENTS AND METHODS

Patients with locally advanced or metastatic breast cancer received nab paclitaxel (125 mg/m(2)) by 30-minute intravenous infusion weekly for 3 of 4 weeks. Patients who were HER2-positive received concurrent trastuzumab.

RESULTS

Seventy-two patients were enrolled; HER2 expression was detected in 22 patients. The overall response rate (ORR) was 42.2% (95% CI, 30%-55%); 5 patients had a complete response (CR) and 22 patients had a partial response (PR). Additionally, 17 patients experienced stable disease (SD), providing an overall benefit (CR + PR + SD) of 68.8%. Patients with HER2-positive tumors had an ORR of 52.4%; the ORR was 38.1% in the HER2-negative population (P = .3). Median progression-free survival was 14.5 months (range, 1-49.3 months) and survival rates at 1 year and 2 years were 69% and 62%, respectively. The most commonly observed toxicities were pain (64%), fatigue (58%), sensory neuropathy (54%), infection (46%), nausea (38%), alopecia (33%), and anemia (33%).

CONCLUSION

Our findings demonstrate that weekly nab paclitaxel has a favorable safety profile and is well tolerated as a first-line treatment for MBC. An ORR of 42% and an overall benefit of 69% is extremely encouraging, particularly in the HER2-positive population where 52% of patients responded.

Nanomedicine for targeted cancer therapy: towards the overcoming of drug resistance

Anticancer drug resistance almost invariably emerges and poses major obstacles towards curative therapy of various human malignancies. In the current review we will distinguish between mechanisms of chemoresistance that are predominantly mediated by ATP-driven multidrug resistance (MDR) efflux transporters, typically of the ATP-binding cassette (ABC) superfamily, and those that are independent of such drug efflux pumps. In recent years, multiple nanoparticle (NP)-based therapeutic systems have been developed that were rationally designed to overcome drug resistance by neutralizing, evading or exploiting various drug efflux pumps and other resistance mechanisms. NPs are being exploited for selective drug delivery to tumor cells, to cancer stem/tumor initiating cells and/or to the supportive cancer cell microenvironment, i.e. stroma or tumor vasculature. Some of these NPs are currently undergoing preclinical in vivo studies as well as advanced stages of clinical evaluation with promising results. Nanovehicles harboring a payload of therapeutic drug combinations for the selective targeting and elimination of tumor cells as well as the simultaneous overcoming of mechanisms of drug resistance are a subject of intense research efforts, some of which are expected to enter clinical trials in the near future. In the present review we highlight novel approaches to selectively target cancer cells and overcome drug resistance phenomena, through the use of various nanometric drug delivery systems. In the near future, it is anticipated that innovative theragnostic nanovehicles will be developed which will harbor four major components: (1) a selective targeting moiety, (2) a diagnostic imaging aid for the localization of the malignant tumor and its micro- or macrometastases, (3) a cytotoxic, small molecule drug(s) or novel therapeutic biological(s), and (4) a chemosensitizing agent aimed at neutralizing a resistance mechanism, or exploiting a molecular "Achilles hill" of drug resistant cells. We propose to name these envisioned four element-containing nanovehicle platform, "quadrugnostic" nanomedicine. This targeted strategy holds promise in paving the way for the introduction of highly effective nanoscopic vehicles for cancer therapeutics while overcoming drug resistance.

CK5/6, EGFR, Ki-67, cyclin D1, and nm23-H1 protein expressions as predictors of pathological complete response to neoadjuvant chemotherapy in triple-negative breast cancer patients

The purpose of this study was to evaluate the importance of biological markers to predict pathologic complete response (pCR) to neoadjuvant chemotherapy (NCT) in patients with locally advanced triple-negative breast cancers (TNBCs). Forty-one patients (18.6%) among 220 breast cancer patients were identified as TNBCs from March 2006 to 2009 were included in this prospective study. The pre-NCT treatment expression levels of Ki-67 proliferation index, estrogen receptor (ER), progesterone receptor (PgR), epidermal growth factor receptor 2 (HER-2), CK5/6, epidermal growth factor receptor (EGFR), cyclin D1, and nm23-H1 were detected by immunohistochemistry (IHC). A total of 180 cycles were administered with the median number of four cycles per patient (range, 4-6). The pCR rate was 34.1% (95% CI, 19.6-48.6%). In univariate analysis, early T stage, clinical response after 2 cycles, negative basal-like, negative EGFR, high Ki-67 proliferation index, and positive nm23-H1 were found to be significantly predictive of a pCR (P = 0.010, 0.040, 0.007, 0.001, 0.019, and 0.010, respectively). Basal-like status and nm23-H1 status were significant for pCR on multivariate analysis (P = 0.004 and 0.031, respectively). Basal-like status and nm23-H1 are independent predictive factors of pCR to neoadjuvant docetaxel plus epirubicin combination chemotherapy in patients with TNBCs.

ER, PgR, HER-2, Ki-67, topoisomerase IIα, and nm23-H1 proteins expression as predictors of pathological complete response to neoadjuvant chemotherapy for locally advanced breast cancer

The purpose of this study was to evaluate the importance of biological markers to predict pathologic complete response (pCR) to neoadjuvant chemotherapy (NCT) in patients with locally advanced breast cancer (LABC) One hundred and twelve consecutive patients with clinical stage III LABC who had received NCT with docetaxel and epirubicin from March 2006 to March 2009 were included in this retrospective study. The pre-NCT treatment expression levels of Ki-67 proliferation index, estrogen receptor (ER), progesterone receptor (PgR), epidermal growth factor receptor 2 (HER-2), Topoisomerase II alpha (Topo-II), and nm23-H1 were detected by immunohistochemistry (IHC). A total of 361 cycles were administered with the median number of three cycles per patient (range, 2-6). The pCR rate was 9.8% (95% CI, 4.3-15.3%). In univariate analysis, poor tumor differentiation, both negative of ER/PgR, negative Topo-II, and positive nm23-H1 were found to be significantly predictive of a pCR. ER/PgR status and nm23-H1 were significant for pCR on multivariate analysis (P = 0.006 and 0.025, respectively). ER/PgR status and nm23-H1 are independent predictive factors of pCR to neoadjuvant docetaxel plus epirubicin combination chemotherapy in patients with LABC.

Neoadjuvant therapy for locally advanced breast cancer: Focus on chemotherapy and biological targeted treatments' armamentarium

Despite progress achieved in diagnosis and therapy in recent years, locally advanced breast cancer (LABC) remains a major clinical issue. Biological characteristics and clinical behavior varies widely, ranging from indolent to locally aggressive or generalized disease. In depth knowledge of biology of cancer progression and cancer could lead to the identification of tumor characteristics associated with outcome. Neoadjuvant chemotherapy (NCT) integrated into a multimodality program is nowadays the established treatment in LABC. Although our efforts in this research task are ongoing, of special clinical interest is the integration of anti-HER2 and other biological therapies, as anti-angiogenesis targeted treatments, that may further improve the long term control of LABC. Clinical management of LABC could be modified based on molecular biology and an approach tailored to each patient will optimize therapy.

Targeted delivery for breast cancer therapy: the history of nanoparticle-albumin-bound paclitaxel

IMPORTANCE OF THE FIELD

Taxanes are agents for the treatment of breast cancer. Paclitaxel is hydrophobic, and available formulations require polyoxyethylated castor oil, Cremphor EL (CrEL) and an ethanol vehicle to allow parental administration. Nanoparticle albumin-bound paclitaxel (nab-P) is a CrEL-free formulation of paclitaxel. The human albumin-stabilized paclitaxel particles have a size of approximately 130 nm, which allows intravenous infusion without capillary blockage.

AREAS COVERED IN THIS REVIEW

Efficacy and safety of nab-P in breast cancer has been compared with paclitaxel and docetaxel in large Phase III and II trials. Additionally, the efficacy and safety of nab-P have been investigated in other single-arm clinical trials, in early and advanced disease.

WHAT THE READER WILL GAIN

Preclinical and clinical development of the drug across all clinical trials published so far, the approved clinical indications, the benefits of this taxane formulation and a look into the future with emphasis on the application in specific subtypes of breast cancer.

TAKE HOME MESSAGE

nab-P has been approved for the treatment of metastatic breast cancer in patients who have failed first-line treatment for metastatic disease and for whom standard, anthracycline-containing therapy is not indicated and represents one of most authoritative and sophisticated applications of nanotechnology in cancer treatment so far.