Aerosol delivery of chemotherapy in an orthotopic model of lung cancer.

The aim of this study was to evaluate the effect on tumour growth of gemcitabine delivered by aerosol in an orthotopic model of lung carcinoma. Large cell carcinoma (NCI-H460) cells were implanted intrabronchially in 24 male BALB/c nude mice on day (d) 0. Aerosols were delivered once a week from d1 to d29 using an endotracheal sprayer. Altogether, 16 animals received gemcitabine at 8 (n=8) and 12 mg.kg-1 (n=8), and eight received a vehicle aerosol. Animals were sacrificed on d36 for histological examination. All animals in the vehicle group developed a large infiltrating carcinoma. Comparatively, four of 13 (31%) animals treated with gemcitabine had no visible tumour and nine of 13 (69%) had a smaller carcinoma with a mean+/-sem largest tumour diameter of 2.05+/-0.7 versus 5+/-0.3 mm in the vehicle group. Gemcitabine was well tolerated at 8 mg.kg-1. At 12 mg.kg-1, three cases of fatal pulmonary oedema were observed, prompting a dose reduction to 8 mg.kg-1 in the remaining animals. A dose effect was observed, with more marked tumour growth inhibition in the animals treated at 12 mg.kg-1 on d1 and d8. In conclusion, in this study, an animal model of aerosolised chemotherapy in lung cancer was developed and demonstrated inhibition of orthotopic tumour growth by aerosol delivery of gemcitabine.

Gene therapy for cystic fibrosis with aerosolized adenovirus-CFTR: characterization of the aerosol and scintigraphic determination of lung deposition in baboons.

For cystic fibrosis (CF) gene therapy using an aerosolized adenovirus expressing the CFTR gene, optimization of the inhalation conditions is a prerequisite to obtain sufficient amount of CFTR protein expression in the target areas of the respiratory tract. For such a purpose, in vivo radioisotopic imaging of the radiolabeled virus is a unique strategy for a quantitative assessment of the actual deposition. In the present study, an adenovirus CFTR (AdCFTR) was labeled with 99m Technetium gamma emitting isotope in such conditions that its bioactivity was preserved. The 99mTc-AdCFTR aerosol was characterized using both laser diffraction and cascade impaction for sizing with further determination of nebulized and inhalable fractions. After administration to baboons, scintigraphic quantitation of the regional lung distribution was performed and the actual dose deposited in the target area was estimated and expressed as an equivalent viral titer. Since a virus scintigraphy is not realistic in a hospital setting, we have developed an approach using 99mTc-DTPA (diethylene triamino pentaacetic acid) that could be used to predict the virus deposition. Indeed, similarities observed between 99mTc-DTPA and 99mTc-adenovirus aerosol imaging patterns validates the use of the 99mTc-DTPA scintigraphy that we propose as a pretherapeutic test for each patient prior to gene transfer.

Radioisotopic imaging allows optimization of adenovirus lung deposition for cystic fibrosis gene therapy.

Cystic fibrosis is a common, heriditary disease resulting from mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Airway transfer of the CFTR gene is a potential strategy to treat or prevent the lung pathology that is the main cause of morbidity and mortality. Among the vectors used for gene therapy, adenoviruses have shown their ability to transfer the CFTR gene to respiratory epithelial cells, using either instillation or nebulization. Our objective was to characterize the lung deposition of aerosolized adenovirus by quantitative radioisotopic imaging, the only noninvasive technique allowing in vivo quantitation of inhaled drugs. We first labeled an adenovirus expressing human CFTR with the gamma-emitting radioisotope, technetium 99m (99mTc), and determined the best labeling conditions to allow preservation of virus bioactivity. We then administered the radioaerosol to baboons, determined lung regional deposition of 99mTc-labeled adenovirus, and compared the expression of CFTR transcripts 3 and 21 days after inhalation. The expression of vector-encoded mRNA ranged from 4 to 22% with respect to the endogenous CFTR mRNA depending on the lung segments. Moreover, we have developed a model using 99mTc-DTPA (diethylenetriamine pentaacetic acid), which can be used, as an alternative to adenovirus, to determine the profile of lung deposition of the vector. This study demonstrates that scintigraphy is a useful technique to achieve optimization of gene administration to the airways.