Louis Gaboury

Sentinel Node Biopsy After Neoadjuvant Chemotherapy in Biopsy-Proven Node-Positive Breast Cancer: The SN FNAC Study

PURPOSE An increasing proportion of patients (> 30%) with node-positive breast cancer will obtain an axillary pathologic complete response after neoadjuvant chemotherapy (NAC). If sentinel node (SN) biopsy (SNB) is accurate in this setting, completion node dissection (CND) morbidity could be avoided. PATIENTS AND METHODS In the prospective multicentric SN FNAC study, patients with biopsy-proven node-positive breast cancer (T0-3, N1-2) underwent both SNB and CND. Immunohistochemistry (IHC) use was mandatory, and SN metastases of any size, including isolated tumor cells (ypN0[i+], ≤ 0.2 mm), were considered positive. The optimal SNB identification rate (IR) ≥ 90% and false-negative rate (FNR) ≤ 10% were predetermined. RESULTS From March 2009 to December 2012, 153 patients were accrued to the study. The SNB IR was 87.6% (127 of 145; 95% CI, 82.2% to 93.0%), and the FNR was 8.4% (seven of 83; 95% CI, 2.4% to 14.4%). If SN ypN0(i+)s had been considered negative, the FNR would have increased to 13.3% (11 of 83; 95% CI, 6.0% to 20.6%). There was no correlation between size of SN metastases and rate of positive non-SNs. Using this method, 30.3% of patients could potentially avoid CND. CONCLUSION In biopsy-proven node-positive breast cancer after NAC, a low SNB FNR (8.4%) can be achieved with mandatory use of IHC. SN metastases of any size should be considered positive. The SNB IR was 87.6%, and in the presence of a technical failure, axillary node dissection should be performed. We recommend that SN evaluation with IHC be further evaluated before being included in future guidelines on the use of SNB after NAC in this setting.

Co-encapsulation of magnetic nanoparticles and doxorubicin into biodegradable microcarriers for deep tissue targeting by vascular MRI navigation

Magnetic tumor targeting with external magnets is a promising method to increase the delivery of cytotoxic agents to tumor cells while reducing side effects. However, this approach suffers from intrinsic limitations, such as the inability to target areas within deep tissues, due mainly to a strong decrease of the magnetic field magnitude away from the magnets. Magnetic resonance navigation (MRN) involving the endovascular steering of therapeutic magnetic microcarriers (TMMC) represents a clinically viable alternative to reach deep tissues. MRN is achieved with an upgraded magnetic resonance imaging (MRI) scanner. In this proof-of-concept preclinical study, the preparation and steering of TMMC which were designed by taking into consideration the constraints of MRN and liver chemoembolization are reported. TMMC were biodegradable microparticles loaded with iron-cobalt nanoparticles and doxorubicin (DOX). These particles displayed high saturation magnetization (Ms = 72 emu g(-1)), MRI tracking compatibility (strong contrast on T2∗-weighted images), appropriate size for the blood vessel embolization (∼50 μm), and sustained release of DOX (over several days). The TMMC were successfully steered in vitro and in vivo in the rabbit model. In vivo targeting of the right or left liver lobes was achieved by MRN through the hepatic artery located 4 cm beneath the skin. Parameters such as flow velocity, TMMC release site in the artery, magnetic gradient and TMMC properties, affected the steering efficiency. These data illustrate the potential of MRN to improve drug targeting in deep tissues.

Magneto-aerotactic bacteria deliver drug-containing nanoliposomes to tumour hypoxic regions

Oxygen depleted hypoxic regions in the tumour are generally resistant to therapies1. Although nanocarriers have been used to deliver drugs, the targeting ratios have been very low. Here, we show that the magneto-aerotactic migration behaviour2 of magnetotactic bacteria3, Magnetococcus marinus strain MC-14, can be used to transport drug-loaded nanoliposomes into hypoxic regions of the tumour. In their natural environment, MC-1 cells, each containing a chain of magnetic iron-oxide nanocrystals5, tend to swim along local magnetic field lines and towards low oxygen concentrations6 based on a two-state aerotactic sensing system2. We show that when MC-1 cells bearing covalently bound drug-containing nanoliposomes were injected near the tumour in SCID Beige mice and magnetically guided, up to 55% of MC-1 cells penetrated into hypoxic regions of HCT116 colorectal xenografts. Approximately 70 drug-loaded nanoliposomes were attached to each MC-1 cell. Our results suggest that harnessing swarms of microorganisms exhibiting magneto-aerotactic behaviour can significantly improve the therapeutic index of various nanocarriers in tumour hypoxic regions.

Steady state and time-resolved fluorescence properties of metastatic and non-metastatic malignant cells from different species

Steady state and time-resolved fluorescence spectroscopy were employed to study the fluorescence from non-metastatic, metastatic and non-tumorigenic cell lines from different species. Excitations at 310 nm and 350 nm were used to monitor tryptophan and reduced nicotinamide adenine dinucleotide (NADH) fluorescence respectively. Subtle and consistent differences were observed between different categories of cell lines. It was found that the tryptophan to NADH fluorescence intensity ratio is higher in metastatic cell lines than in non-metastatic and normal cell lines. The fluorescence decay of the tryptophan residue in different cell lines was best described by triple exponential kinetics, whereas the NADH fluorescence decay was best described by mainly double and, in some cases, triple exponential kinetics. The average fluorescence lifetimes for tryptophan were in the range 2.5-3.7 ns. The average lifetime of NADH was lower (by a factor of approximately three) in metastatic cells than in non-metastatic cells and this finding is consistent for cell lines from different origins (rat or human). Correcting the fluorescence intensity for the average fluorescence lifetime of each species and for the volume of each cell line, it was shown that the concentrations of tryptophan and NADH are consistently higher in malignant metastatic cancer cells than in non-metastatic cells.

Glycoprotein Nonmetastatic B Is an Independent Prognostic Indicator of Recurrence and a Novel Therapeutic Target in Breast Cancer

Purpose: Although the murine orthologue of glycoprotein nonmetastatic B (GPNMB), Osteoactivin, promotes breast cancer metastasis in an in vivo mouse model, its importance in human breast cancer is unknown. We have examined the significance of GPNMB expression as a prognostic indicator of recurrence and assessed its potential as a novel therapeutic target in breast cancer. Experimental Design: The clinical significance of GPNMB expression in breast cancer was addressed by analyzing GPNMB levels in several published gene expression data sets and two independent tissue microarrays derived from human breast tumors. GPNMB-expressing human breast cancer cell lines were further used to validate a toxin-conjugated anti-GPNMB antibody as a novel therapeutic agent. Results: GPNMB expression correlates with shorter recurrence times and reduced overall survival of breast cancer patients. Epithelial-specific GPNMB staining is an independent prognostic indicator for breast cancer recurrence. GPNMB is highly expressed in basal and triple-negative breast cancers and is associated with increased risk of recurrence within this subtype. GPNMB expression confers a more migratory and invasive phenotype on breast cancer cells and sensitizes them to killing by CDX-011 (glembatumumab vedotin), a GPNMB-targeted antibody-drug conjugate. Conclusions: GPNMB expression is associated with the basal/triple-negative subtype and is a prognostic marker of poor outcome in patients with breast cancer. CDX-011 (glembatumumab vedotin) is a promising new targeted therapy for patients with metastatic triple-negative breast cancers, a patient population that currently lacks targeted-therapy options. Clin Cancer Res; 16(7); 2147–56. ©2010 AACR.

CXCR4 peptide antagonist inhibits primary breast tumor growth, metastasis and enhances the efficacy of anti-VEGF treatment or docetaxel in a transgenic mouse model

CXCR4 is a chemokine receptor implicated in the homing of cancer cells to target metastatic organs, which overexpress its ligand, stromal cell‐derived factor (SDF)‐1. To determine the efficacy of targeting CXCR4 on primary tumor growth and metastasis, we used a peptide inhibitor of CXCR4, CTCE‐9908, that was administered in a clinically relevant approach using a transgenic breast cancer mouse model. We first performed a dosing experiment of CTCE‐9908 in the PyMT mouse model, testing 25, 50 and 100 mg/kg versus the scrambled peptide in groups of 8–16 mice. We then combined CTCE‐9908 with docetaxel or DC101 (an anti‐VEGFR2 monoclonal antibody). We found that increasing doses of CTCE‐9908 alone slowed the rate of tumor growth, with a 45% inhibition of primary tumor growth at 3.5 weeks of treatment with 50 mg/kg of CTCE‐9908 (p = 0.005). Expression levels of VEGF were also found to be reduced by 42% with CTCE‐9908 (p = 0.01). In combination with docetaxel, CTCE‐9908 administration decreased tumor volume by 38% (p = 0.02), an effect that was greater than that observed with docetaxel alone. In combination with DC101, CTCE‐9908 also demonstrated an enhanced effect compared to DC101 alone, with a 37% decrease in primary tumor volume (p = 0.01) and a 75% reduction in distant metastasis (p = 0.009). In combination with docetaxel or an anti‐angiogenic agent, the anti‐tumor and anti‐metastatic effects of CTCE‐9908 were markedly enhanced, suggesting potentially new effective combinatorial therapeutic strategies in the treatment of breast cancer, which include targeting the SDF‐1/CXCR4 ligand/receptor pair.

Noninvasive quantitation of human liver steatosis using magnetic resonance and bioassay methods

The purpose was to evaluate the ability of three magnetic resonance (MR) techniques to detect liver steatosis and to determine which noninvasive technique (MR, bioassays) or combination of techniques is optimal for the quantification of hepatic fat using histopathology as a reference. Twenty patients with histopathologically proven steatosis and 24 control subjects underwent single-voxel proton MR spectroscopy (MRS; 3 voxels), dual-echo in phase/out of phase MR imaging (DEI) and diffusion-weighted MR imaging (DWI) examinations of the liver. Blood or urine bioassays were also performed for steatosis patients. Both MRS and DEI data allowed to detect steatosis with a high sensitivity (0.95 for MRS; 1 for DEI) and specificity (1 for MRS; 0.875 for DEI) but not DWI. Strong correlations were found between fat fraction (FF) measured by MRS, DEI and histopathology segmentation as well as with low density lipoprotein (LDL) and cholesterol concentrations. A Bland-Altman analysis showed a good agreement between the FF measured by MRS and DEI. Partial correlation analyses failed to improve the correlation with segmentation FF when MRS or DEI data were combined with bioassay results. Therefore, FF from MRS or DEI appear to be the best parameters to both detect steatosis and accurately quantify fat liver noninvasively.

Spectroscopic and photophysical properties of some new rhodamine derivatives in cationic, anionic and neutral micelles

Abstract The spectroscopic and photophysical characterization of rhodamine 123 (dye 1 ), 4,5-dibromorhodamine methyl ester (dye 2 ) and 4,5-dibromorhodamine n-butyl ester (dye 3 ) are reported in homogeneous media like water and some alcohols and also in microheterogeneous media; anionic sodium dodecylsulfate (SDS), cationic cetyltrimethylammonium bromide (CTAB) and neutral triton X-100 (TX) micelles. The selective biodistribution of these ionic drugs in tissues and membranes strongly influence their photosentisizing properties which have been part of our earlier studies. Results suggest that the hydrogen bonding capability of the amino end group lone pair of these dyes dominates in water. All these dyes interact with anionic SDS micelles. The interaction is mainly electrostatic in nature. At low SDs concentrations (below c.m.c.), dye-SDS aggregate formation takes place. But above c.m.c. only the monomeric dye form is observed. The penetration of dye 3 in SDS is a little less compared to dyes 1 and 2 . Dyes 2 and 3 show a finite interaction with CTAB micelle unlike dye 1 . With neutral TX micelles all the dyes form strong complexes. The fluorescence quantum yield ( Φ F ) of these three dyes in TX is lower. In time-resolved fluorescence experiments, two lifetimes are observed. The effects of the TX concentration on the fluorescence decay are measured. The decay associated spectra of dye 2 in TX are obtained by global compartmental analysis. The dye-surfactant interaction mechanisms are also discussed.

Phototoxicity of Some Bromine‐Substituted Rhodamine Dyes: Synthesis, Photophysical Properties and Application as Photosensitizers

Abstract— The synthesis of some bromine‐substituted rhodamine derivatives viz., 4,5‐dibromorhodamine methyl ester (dye 2) and 4,5‐dibromorhodamine n ‐butyl ester (dye 3) are reported. These dyes were synthesized to promote a more efficient cancer cell photosensitizer for potential use in in vitro bone marrow purging in preparation for autologous bone marrow transplantation. Spectroscopic and photo‐physical characterization of these dyes together with rhodamine 123 (dye 1) are reported in water, methanol, eth‐anol and also in a microheterogeneous system, sodium dodecyl sulfate. The possible mechanism of photosensi‐tization is characterized in terms of singlet oxygen efficiency of these dyes. Singlet oxygen quantum yields for bromine‐substituted dyes are in the range of 0.3‐0.5 depending on the solvent. For dye 1 no singlet oxygen production is found. The photodynamic actions of these dyes in different cell lines are tested. It was found that dye 2 and dye 3 are efficient photosensitizers and mediate eradication of K562, EM2, myeloid cell lines (CML) and the SMF‐AI rhabdomyosarcoma line.

The Influence of Tumor-Host Interactions in the Stromal Cell-Derived Factor-1/CXCR4 Ligand/Receptor Axis in Determining Metastatic Risk in Breast Cancer

The chemokine stromal cell-derived factor-1 (SDF-1) may function to attract CXCR4-expressing cancer cells to metastatic organs. We have previously demonstrated that low plasma SDF-1, a host-derived marker, increases distant metastatic risk in breast cancer. We therefore hypothesized that tumors overexpressing the SDF-1 receptor CXCR4 have an enhanced ability to metastasize in patients with low plasma SDF-1 levels. In this study, we determined the prognostic significance of activated CXCR4, or phosphorylated CXCR4 (p-CXCR4), and CXCR7, another receptor for SDF-1. Immunohistochemistry was performed on a tissue microarray built using 237 samples from the same cohort of patients for which we measured plasma SDF-1 levels. We found that the prognostic value of p-CXCR4 expression (hazard ratio or HR, 3.95; P = 0.004) was superior to total CXCR4 expression (HR, 3.20; P = 0.03). The rate of breast cancer-specific mortality was much higher in patients with both high p-CXCR4 expression and low plasma SDF-1 levels (HR, 5.96; P < 0.001) than either low plasma SDF-1 (HR, 3.59; P = 0.01) or high p-CXCR4 expression (HR, 3.83; P = 0.005) alone. The added prognostic value of low plasma SDF-1 was only effective in patients with high p-CXCR4 expression, and as such, provides clinical validation for modulation of the metastatic potential of tumor cells by an inherent host-derived metastatic risk factor.