Abstract CT059: Systemic administration using targeted gene delivery with SGT-RB94 shows evidence of tumor targeting and anticancer activity: a phase I first-in-man trial

Background: Development of gene therapy has been limited by our inability to systemically administer treatment which selectively targets tumor tissue. We developed an SGT-RB94 nanocomplex composed of cationic liposome encapsulating plasmid DNA encoding the RB94 gene which had previously been shown to selectively kill cancer cells but not non-transformed human cells. The surface of the liposome is decorated with a single chain antibody fragment to the transferrin receptor to target the nanocomplex to cancer cells.

Methods: We performed a phase I trial of single agent SGT-RB94 in patients with previously treated metastatic cancer. Treatment with SGT-RB94 was administered twice a week for 3 weeks out of four using a fixed at a fixed DNA dose of 0.6, 1.2, or 2.4 mg pDNA. Radiographic imaging was performed every 2 cycles to evaluate for response. When possible, a biopsy of a metastatic site was performed, after beginning treatment to evaluate for targeting of the gene product. PCR was performed to show expression of SGT-94 in RB+ tumors, RB94 protein production was confirmed using Western blotting.

Results: Thirteen patients were treated with 11 clinically evaluable for response. Dose-limiting toxicity was not observed at the 2.4 mg dose. A total of 181 doses of SGT-94 were administered. The treatment was well tolerated with the most frequent treatment related toxicities being Grade 1-2 fever and chills (27%), thrombocytopenia (45%), neutropenia (18%), and hypotension (18%). The only grade 3-4 toxicity were lymphopenia (9%), and neutropenia (9%). The fever/chills and hypotension most typically occurred after the first dose, and responding with steroids. The neutropenia and thrombocytopenia were also transient and improved with continued dosing.

There was evidence of clinical activity with a complete response in a lung metastases; this patient was retreated upon progression, and had a partial response in his peritoneal implants. Two patients continued to have stable disease after 4-5 cycles of treatment. Two patients had RB- tumors by immunohistochemistry. One had a post-treatment biopsy showing evidence of cytoplasmic staining for the RB protein with extensive tumor necrosis following treatment, but this tumor ultimately progressed. One patient with stable disease had surgical consolidation with wedge resection of his lung metastases which showed RB94 expression by PCR, and protein production by Western blot in two separate tumors, but not in his normal lung tissue.

Conclusions: Systemic delivery of SGT-RB94 was well tolerated with evidence of clinical activity and selective targeting of tumor tissue, overcoming a major limitation to current gene therapy strategies. Further development of SGT-RB94 as a treatment modality is warranted.

Citation Format: Arlene Siefker-Radtke, Xin-qiao Zhang, Kathleen F. Pirollo, Esther H. Chang, Chris P. Leung, Charles Guo, Randall E. Millikan, William F. Benedict. Systemic administration using targeted gene delivery with SGT-RB94 shows evidence of tumor targeting and anticancer activity: a phase I first-in-man trial. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT059.

Active finite element analysis of skeletal muscle-tendon complex during isometric, shortening and lengthening contraction

An active finite element model was developed to predict the mechanical behaviors of skeletal muscle-tendon complex during isometric, shortening and lengthening contraction. The active finite element was created through incorporation of a user-defined material property into ABAQUS finite element code. The active finite element is controlled by a motor element that is activated by a mathematical function. The nonlinear passive behavior of the muscle was defined by the viscoelastic elements and can be easily altered to other properties by using other elements in the material library without the need of re-defining the constitutive relation of the muscle. The isometric force-length relationship, force-strain relations of the muscle-tendon complex during both shortening and lengthening contraction and muscle relaxation response were predicted using the proposed finite element model. The predicted results were found to be in good agreement with available experimental data. In addition, the stress distribution in the muscle-tendon complex during isometric, shortening and lengthening contractions was simulated. The location of the maximum stress may provide useful information for studying muscle damage and fatigue in the future.

Quantification of apoptotic DNA fragmentation in a transformed uterine epithelial cell line, HRE-H9, using capillary electrophoresis with laser-induced fluorescence detector (CE-LIF)

Apoptotic cell death of uterine epithelial cells is thought to play an important role in the onset of menstruation and the successful implantation of an embryo during early pregnancy. Abnormal apoptosis in these cells can result in dysmenorrhoea and infertility. In addition, decreased rate of epithelial apoptosis likely contributes to endometriosis. A key step in the onset of apoptosis in these cells is cleavage of the genomic DNA between nucleosomes, resulting in polynucleosomal-sized fragments of DNA. The conventional technique for assessing apoptotic DNA fragmentation uses agarose (slab) gel electrophoresis (i.e. DNA laddering). However, recent technological advances in the use of capillary electrophoresis (CE), particularly the introduction of the laser-induced fluorescence detector (LIF), has made it possible to perform DNA laddering with improved automation and much greater sensitivity. In the present study, we have further developed the CE-LIF technique by using a DNA standard curve to quantify accurately the amount of DNA in the apoptotic DNA fragments and have applied this new quantitative technique to study apoptosis in a transformed uterine epithelial cell line, the HRE-H9 cells. Apoptosis was induced in the HRE-H9 cells by serum deprivation for 5, 7 and 24 h, resulting in increased DNA fragmentation of 2.2-, 3.1- and 6.2-fold, respectively, above the 0 h or plus-serum controls. This ultrasensitive CE-LIF technique provides a novel method for accurately measuring the actions of pro- or anti-apoptotic agents or conditions on uterine epithelial cell lines.

Determination of vitamin U and its degradation products by high- performance liquid chromatography with fluorescence detection

A high-performance liquid chromatographic method has been developed for the determination of vitamin U in tablets and capsules. Threonine was employed as the internal standard through the assay. The o-phthalaldehyde derivatives were prepared and then chromatographed isocratically on a reversed-phase C18 column. The optimum reaction time for both vitamin U and threonine at pH 10.5 is 5 min. Vitamin U and its major degradation product in the dosage forms, viz., methionine sulphoxide, were separated and quantified with a relative standard deviation of about 1%, using a fluorescence detector with excitation and emission wavelengths at 340 and 450 nm respectively. A linear relationship has been established between the peak area ratio of vitamin U/threonine and the concentration of vitamin U over the range of 2.5-50 micrograms/ml.

Determination of chlorpheniramine maleate in tablets by second-derivative absorption spectrophotometry

A rapid method for the determination of chlorpheniramine maleate in tablets using second-derivative absorption spectrophotometry is described. The method has the advantage of requiring simple sample preparation and having accuracy comparable to the official acid-alkaline solvent extraction procedure. Results of recovery tests were close to 100%.