Vuong Trieu

Increased antitumor activity, intratumor paclitaxel concentrations, and endothelial cell transport of cremophor-free, albumin-bound paclitaxel, ABI-007, compared with cremophor-based paclitaxel.

ABI-007, an albumin-bound, 130-nm particle form of paclitaxel, was developed to avoid Cremophor/ethanol-associated toxicities in Cremophor-based paclitaxel (Taxol) and to exploit albumin receptor-mediated endothelial transport. We studied the antitumor activity, intratumoral paclitaxel accumulation, and endothelial transport for ABI-007 and Cremophor-based paclitaxel. Antitumor activity and mortality were assessed in nude mice bearing human tumor xenografts [lung (H522), breast (MX-1), ovarian (SK-OV-3), prostate (PC-3), and colon (HT29)] treated with ABI-007 or Cremophor-based paclitaxel. Intratumoral paclitaxel concentrations (MX-1-tumored mice) were compared for radiolabeled ABI-007 and Cremophor-based paclitaxel. In vitro endothelial transcytosis and Cremophor inhibition of paclitaxel binding to cells and albumin was compared for ABI-007 and Cremophor-based paclitaxel. Both ABI-007 and Cremophor-based paclitaxel caused tumor regression and prolonged survival; the order of sensitivity was lung > breast congruent with ovary > prostate > colon. The LD(50) and maximum tolerated dose for ABI-007 and Cremophor-based paclitaxel were 47 and 30 mg/kg/d and 30 and 13.4 mg/kg/d, respectively. At equitoxic dose, the ABI-007-treated groups showed more complete regressions, longer time to recurrence, longer doubling time, and prolonged survival. At equal dose, tumor paclitaxel area under the curve was 33% higher for ABI-007 versus Cremophor-based paclitaxel, indicating more effective intratumoral accumulation of ABI-007. Endothelial binding and transcytosis of paclitaxel were markedly higher for ABI-007 versus Cremophor-based paclitaxel, and this difference was abrogated by a known inhibitor of endothelial gp60 receptor/caveolar transport. In addition, Cremophor was found to inhibit binding of paclitaxel to endothelial cells and albumin. Enhanced endothelial cell binding and transcytosis for ABI-007 and inhibition by Cremophor in Cremophor-based paclitaxel may account in part for the greater efficacy and intratumor delivery of ABI-007.

Gemcitabine Plus nab-Paclitaxel Is an Active Regimen in Patients With Advanced Pancreatic Cancer: A Phase I/II Trial

PURPOSE The trial objectives were to identify the maximum-tolerated dose (MTD) of first-line gemcitabine plus nab-paclitaxel in metastatic pancreatic adenocarcinoma and to provide efficacy and safety data. Additional objectives were to evaluate positron emission tomography (PET) scan response, secreted protein acidic and rich in cysteine (SPARC), and CA19-9 levels in relation to efficacy. Subsequent preclinical studies investigated the changes involving the pancreatic stroma and drug uptake. PATIENTS AND METHODS Patients with previously untreated advanced pancreatic cancer were treated with 100, 125, or 150 mg/m(2) nab-paclitaxel followed by gemcitabine 1,000 mg/m(2) on days 1, 8, and 15 every 28 days. In the preclinical study, mice were implanted with human pancreatic cancers and treated with study agents. RESULTS A total of 20, 44, and three patients received nab-paclitaxel at 100, 125, and 150 mg/m(2), respectively. The MTD was 1,000 mg/m(2) of gemcitabine plus 125 mg/m(2) of nab-paclitaxel once a week for 3 weeks, every 28 days. Dose-limiting toxicities were sepsis and neutropenia. At the MTD, the response rate was 48%, with 12.2 median months of overall survival (OS) and 48% 1-year survival. Improved OS was observed in patients who had a complete metabolic response on [(18)F]fluorodeoxyglucose PET. Decreases in CA19-9 levels were correlated with increased response rate, progression-free survival, and OS. SPARC in the stroma, but not in the tumor, was correlated with improved survival. In mice with human pancreatic cancer xenografts, nab-paclitaxel alone and in combination with gemcitabine depleted the desmoplastic stroma. The intratumoral concentration of gemcitabine was increased by 2.8-fold in mice receiving nab-paclitaxel plus gemcitabine versus those receiving gemcitabine alone. CONCLUSION The regimen of nab-paclitaxel plus gemcitabine has tolerable adverse effects with substantial antitumor activity, warranting phase III evaluation.

Phase I and Pharmacokinetics Trial of ABI-007, a Novel Nanoparticle Formulation of Paclitaxel in Patients With Advanced Nonhematologic Malignancies

PURPOSE ABI-007 is a novel solvent-free, albumin-bound, 130-nm particle formulation of paclitaxel designed to avoid solvent-related toxicities and to deliver paclitaxel to tumors via molecular pathways involving an endothelial cell-surface albumin receptor (gp60) and an albumin-binding protein expressed by tumor cells and secreted into the tumor interstitium (secreted protein acid rich in cysteine). This study determined the maximum-tolerated dose (MTD) of ABI-007 monotherapy administered weekly (three weekly doses, repeated every 4 weeks) and assessed the pharmacokinetics of paclitaxel administered as ABI-007. PATIENTS AND METHODS Patients with advanced nonhematologic malignancies received ABI-007 without premedication at dose levels from 80 to 200 mg/m(2) as a 30-minute intravenous infusion once a week for 3 weeks, followed by 1 week of rest (one cycle). RESULTS Thirty-nine patients were treated with an average of five cycles of ABI-007; 33% of patients received > or = six cycles of treatment. MTDs for heavily and lightly pretreated patients were 100 and 150 mg/m(2), respectively; and the dose-limiting toxicities were grade 4 neutropenia and grade 3 peripheral neuropathy, respectively. Maximum paclitaxel concentration and area under the curve increased linearly with dose. Dose-dependent changes in plasma clearance did not occur. Partial responses were observed in five patients with breast, lung, and ovarian cancers, all of whom had previously been treated with paclitaxel containing polyoxyethylated castor oil in the formulation. CONCLUSION This study demonstrated that weekly ABI-007 can be administered at doses exceeding those typically used for paclitaxel containing polyoxyethylated castor oil. Pharmacokinetics were linear over the dose range studied. Antitumor responses occurred in patients previously treated with paclitaxel containing polyoxyethylated castor oil.

Improved effectiveness of nanoparticle albumin-bound (nab) paclitaxel versus polysorbate-based docetaxel in multiple xenografts as a function of HER2 and SPARC status.

Nanoparticle albumin-bound (nab)-paclitaxel (Abraxane) is an albumin-bound 130-nm particle form of paclitaxel that demonstrated higher efficacy and was well tolerated compared with solvent-based paclitaxel (Taxol) and docetaxel (Taxotere) in clinical trials for metastatic breast cancer. Nab-paclitaxel enhances tumor targeting through gp60 and caveolae-mediated endothelial transcytosis and the association with the albumin-binding protein SPARC (secreted protein, acidic and rich in cysteine) in the tumor microenvironment. The overexpression of human epidermal growth factor receptor-2 (HER2) in breast cancer has been shown to correlate with resistance to paclitaxel. To evaluate the importance of HER2 and SPARC status in determining the relative efficacy of nab-paclitaxel compared with polysorbate-based docetaxel, nude mice bearing six different human tumor xenografts were treated with nab-paclitaxel (MX-1: 15 mg/kg, once a week for 3 weeks; LX-1, MDA-MB-231/HER2+, PC3, and HT29: 50 and 120 mg/kg, every 4 days three times ; MDA-MB-231: 120 and 180 mg/kg, every 4 days three times) and polysorbate-based docetaxel (15 mg/kg). HER2 and SPARC status were analyzed by RT-PCR and immunohistochemical staining. MDA-MB-231 and MX-1 breast and LX-1 lung cancers were HER2 negative and low in SPARC expression. Nab-paclitaxel at submaximum-tolerated dosage was significantly more effective than polysorbate-based docetaxel at its maximum-tolerated dosage in these three HER2-negative tumors. The HER2-positive tumors had variable SPARC expression, with MDA-MB-231/HER2+ <PC3 <HT29. In these HER2-positive tumors, nab-paclitaxel was equal to or better than polysorbate-based docetaxel in tumors with medium to high SPARC levels (PC3 and HT29), but not in MDA-MB-231/HER2+ tumors with low SPARC expression. These results demonstrated that the relative efficacy of nab-paclitaxel was significantly higher compared with polysorbate-based docetaxel in HER2-negative tumors (three of three) and in HER2-positive tumors with high levels of SPARC. HER2 and SPARC expression may be useful biomarkers in determining antitumor effectiveness for taxanes.

IG-001 - A Non-Biologic Nanoparticle Paclitaxel for the Treatment of Solid Tumors

IG-001 - A Non-Biologic Nanoparticle Paclitaxel for the Treatment of Solid Tumors nab-paclitaxel (Abraxane®)—a Cremophor-free, albumin-bound, nanoparticle form of paclitaxel—though a breakthrough in paclitaxel formulation, has inherent problems associated with any biologics. IG-001 (Genexol-PM®), a polymeric micellar formulation forms nanoparticles with paclitaxel containing a hydrophobic core and a hydrophilic shell and is being developed as the next generation nanoparticle paclitaxel. Its target indications are solid tumors including Breast, Lung, Ovarian, Bladder, Melanoma and Pancreatic cancers. Similar to nab-paclitaxel, due to its very fast dissolution in plasma, high tumor/plasma ratio, and dose-proportional PK, IG-001 is a superior alternative to Taxol®. Moreover, despite a lack of serum albumin in its formulation, IG-001 takes full advantage of its ability to rapidly deliver paclitaxel to the targeted tissue via an albuminmediated transport, as previously described for nab-paclitaxel.

Combination Regimens of nab-Rapamycin (ABI-009) Effective Against MDA-MB-231 Breast-Tumor Xenografts.

Background: The mammalian target of Rapamycin (mTOR) is a key intracellular kinase integrating cell proliferation and survival and is an attractive target for cancer therapy. Nab -rapamycin (ABI-009) was developed using proprietary nab -technology and showed dose-linear pharmacokinetics, safety up to 90 mg/kg and effective antitumor activity at 40 mg/kg in the human-tumor-xenograft panel. The goal of this study was to test the effectiveness of different combination regimens for ABI-009 against MDA-MB-231 breast-tumor xenografts. Materials and methods: Subcutaneous human-breast (MDA-MB-231) tumors were grown in athymic nude mice and treated intravenously (IV) with ABI-009 alone at 40 mg/kg (3xwkly/4wks) and in combination with Erlotinib (50 and 100 mg/kg/day/4wks, IP), Cetuximab (20 and 40 mg/kg, 3xwkly/4wks, IP), Doxorubicin (2 and 5 mg/kg, wkly/10 wks, IV), Oxaliplatin (5 and 10 mg/kg wkly/4 wks, IV), SAHA (50 mg/kg, qdx7 or qdx14, IP), and Perifosine (30 and 60 mg/kg, 3xwkly/4wks, PO). The animal weights and tumor measurements were recorded three times weekly and adverse observations recorded. Results: ABI-009 was highly effective as a single agent against MDA-MB-231 breast tumor xenografts with 75% tumor-growth inhibition (TGI). Combination with Erlotinib resulted in TGI of 85% and 95% (50 and 100 mg/kg, respectively), 83% and 87% for Cetuximab (20 and 40 mg/kg, respectively), 83% and 90% for Doxorubicin (2.5 and 5 mg/kg, respectively), 82% and 85% for Oxaliplatin (5 and 10 mg/kg, respectively), 82% and 90% for SAHA (7 and 14 day treatment, respectively), and 92% and 96% for Perifosine (30 and 60 mg/kg, respectively). Notably, Erlotinib and Perifosine were found to synergize with ABI-009 resulting in maximum TGI and tumor growth delay. Discussion: ABI-009 ( nab -rapamycin) alone was highly effective against MDA-MB-231 human-breast-tumor xenografts. Antitumor activity of ABI-009 was significantly increased in combination with kinase inhibitors, Erlotinib (EGFR-kinase inhibitor) and Perifosine (AKT inhibitor). Antitumor activity of ABI-009 was also significantly increased in combination with Doxorubicin – a topoisomerase inhibitor, and SAHA – an HDAC inhibitor, but not in combination with Oxaliplatin – a DNA crosslinker. In contrast, combination of ABI-009 with anti-EGFR monoclonal antibody, Cetuximab was not effective. The synergy of these combinations confirmed that rapamycin is active only on TORC1 and that suppression of TORC2 via AKT or PI3K pathways is a means of increasing activity of mTOR inhibitors with potential relevance to breast cancer. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6106.

Albumin-Binding and Angiogenic Domains of SPARC Located at Its C-Terminus.

Background: SPARC (Secreted Protein Acidic and Rich in Cysteine) is an albumin-binding glycoprotein overexpressed in breast cancer and is associated with poor prognosis and shorter overall survival. We have previously shown that SPARC expression appeared to correlate with response to nanoparticle albumin-bound (nab) paclitaxel (Abraxane) in head-and-neck and pancreatic-cancer patients. To further define the role of SPARC, recombinant-human SPARC (rhSPARC) was characterized to identify its albumin-binding and angiogenic domain.Materials and methods: The albumin-binding site on SPARC was defined by testing the binding of Alexa 488-labeled BSA to immobilized rhSPARC in a solid-phase-binding assay and in a competitive-binding assay in presence of increasing concentration of various SPARC-derived peptides. The angiogenic activity of rhSPARC was evaluated using a HUVEC tube-formation assay.Results: The SPARC albumin-binding assay revealed a pattern of saturable and specific binding with an estimated Kd of 700 µM very near the known plasma concentration of albumin (600 µM). Competitive binding with Cathepsin K-digested SPARC and SPARC-derived peptides defined the albumin-binding domain to be amino acids 209-223 in the C-terminal region. In the HUVEC tube-formation assay, rhSPARC was pro-angiogenic at 10 µg/ml and anti-angiogenic at 100 µg/ml. The angiogenic domain of SPARC was located to the C-terminal of SPARC.Discussion: The albumin-binding domain of SPARC was located to residues aa209-223, supporting its role as a target for nab-technology-based drug delivery. We confirmed that SPARC can promote angiogenesis at physiological concentrations, contributing to the role of SPARC in a more aggressive tumor phenotype. The angiogenic domain of SPARC is located within a 54-aa sequence of its C-terminus. SPARC could be a potential therapeutic target and a biomarker for predicting response to nab-paclitaxel. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2144.

Abstract 4082: U6 upregulation in cancer

Background: U6 snRNA is a non-coding RNA that is a component of the splicesome, which is involved in RNA splicing of the pre-mRNA. In view of the critical function performed by U6 snRNA in RNA splicing and therefore cellular proliferation, it is possible that U6 would play a role in cancer development. In this study, U6 levels were examined across various tumor types. Methods: Detection of U6 snRNA in various normal and tumor tissue was performed with Tissue Microarray by In Situ Hybridization technique. The 5′-DIG-labeled U6 LNA probe (sequence 5′-CACGAATTTGCGTGTCATCCTT-3′) from Exiqon was used for this study and the Vector Red was used as substrate. The U6 stained tissue microarray was then scanned by GenePix 6.0 (Molecular Devices) at 532 nm to detect the staining intensity from each tissue sample. Each sample on the TMA was also visually scored by the intensity on a scale of 0 to 4. A quantitative real-time PCR assay was also used to confirm the overexpression of U6 snRNA in breast and other cancers. Results: A baseline study using tumor microarrays and visual scoring suggested that U6 snRNA levels were increased in tumors relative to normal tissues. This was confirmed using the rapid U6 snRNA ISH for colon carcinoma, melanoma, pancreatic carcinoma, renal carcinoma, and lung carcinoma. In all cases, U6 levels were significantly elevated in tumor versus normal by t-test. By RT-PCR, U6 snRNA levels were also found to be increased relative to the corresponding normal tissue in carcinoma of the breast, colon, kidney, liver, lung, and ovary. No increase over the corresponding normal tissue was found in prostate and thyroid carcinomas. In breast carcinoma, there was no correlation between U6 snRNA levels and estrogen receptor status, progesterone receptor status or erb-B2 expression levels. Conclusions: Using a scanning system and tumor tissue array, we were able to demonstrate the use of microarray scanner to quantitate ISH signal. Application of this technology to U6 snRNA demonstrated that U6 is significantly elevated in most cancer types examined. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4082.

IG-001—A non-biologic micellar paclitaxel formulation for the treatment of metastatic Breast cancer

We have recently shown that the dissolution profile of IG-001 is very similar to that of nabpaclitaxel/Abraxane®. Once injected into the circulation, both formulations quickly dissolve into paclitaxel complexed with endogenous circulating albumin, suggesting that both formulations deliver paclitaxel to the targeted tissue via albuminmediated transport. Herein, we provide a summary report of our clinical studies in Metastatic Breast Cancer (MBC) that includes two Phase 2 studies, interim results for a Phase 3, as well as a Phase 4 post-marketing surveillance (PMS) study.

Antitumor activity, and antiangiogenic activity of nanoparticle albumin-bound nab-rapamycin in combination with nab-paclitaxel.

Abstract #3125 Background: Rapamycin inhibits downstream signals from the mammalian target of rapamycin (mTOR), a known kinase member of a signaling pathway that promotes tumor growth. Rapamycin9s poor aqueous solubility and poor chemical stability have limited its development as an intravenous (IV) anticancer agent. Nab -rapamycin utilizes the albumin-bound technology to allow for IV administration of rapamycin and has demonstrated dose-linear pharmacokinetics and safety up to 90 mg/kg with effective antitumor activity at 40 mg/kg against a human panel of tumor xenografts. This study investigated the efficacy of combined therapy with nab -paclitaxel (Abraxane®) utilizing invasive human breast (MDA-MB-231) and colon (HT29) cancer xenograft models.
 Material and Methods: Xenograft transplants using luciferase-tagged MDA-MB-231 cells were implanted into mammary fatpad of SCID mice and allowed to reach 460 mm 3 in size prior to IV administration of saline (vehicle, n = 9); nab -rapamycin, 3x wkly for 2 wks at 40 mg/kg ( nab -rap-2W; n = 8); nab -rapamycin, 3x wkly for 4 wks at 40 mg/kg ( nab -rap-4W; n = 8); Abraxane, qdx5 at 30 mg/kg (ABX; n = 8); nab -rap-2W + ABX (n = 9); or nab -rap-4W + ABX (n = 8). HT29 xenografts were also treated with nab -rap-4W (n = 8) and nab -rap-4W + ABX (10 mg/kg, qdx5, IP, n = 8). The in vivo antiangiogenic effect of nab -rapamycin was evaluated using the standard in vivo chick chorioallantoic membrane (CAM) assay with 3-day old embryos (n = 18).
 Results: Relative to vehicle controls, nab -rap-2W ( P nab -rap-4W ( P P nab -rapamycin + ABX with TGI of 81% and 86% for nab -rap-2W + ABX and nab -rap-4W + ABX groups, respectively. For HT29 tumors, the combination of ABX and nab -rapamycin also showed greater TGI (89%) compared to nab -rapamycin alone (81%). In the chick CAM assay, nab -rapamycin demonstrated antiangiogenic efficacy at doses of 10 µg and above without affecting embryo viability.
 Conclusions: Combination therapy of nab -rapamycin and Abraxane was more effective at inhibiting breast and colon xenograft tumor growth than single therapy of either drug. The enhanced antitumor activity seen with combined nab -rapamycin-Abraxane may in part be due to the observed antiangiogenic activity of nab -rapamycin. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3125.