Publications and Presentations

Abstract

Background and Purpose: In vitro inhalation toxicity was assessed to evaluate the potential respiratory toxicity of two test articles of the same organotin chemical class, a known industrial chemical Dimethyltin dichloride (DMTC) and a new organotin chemical of the same class (MBT-1).

Methods: Two in vitro experiments were conducted using reconstructed 3D human airway epithelial tissues (EpiAirway AIR-100, MatTek EpiAirway™). The first experiment tested both chemicals dissolved in vehicle at concentrations recommended by the MatTeck protocol (20–200 mg/mL) to determine each chemical's GSH (Globally Harmonized System Classification hazard category, 2003). Then extrapolation of the expected in vivo air concentration was made based on the GSH classification levels of in vivo toxicity. To assess the relevance of established inhalation toxicity to a real-world exposure scenarios, a second experiment was performed using significantly lower in vitro concentrations—0.002 – 0.02 mg/mL at serial dilutions— representing a 1,000- to 10,000-fold reduction from the toxic in vitro doses used in the first Experiment. These concentrations were chosen based on the worst-case predicted exposure levels in the human breathing zone after the possible spillage of these chemicals.

Results: Both chemicals showed significant cytotoxicity in the first experiment at the tested in vitro concentrations, with the cell viability falling well below the 75% threshold, classifying them within to GSH Hazard Category 1 or 2. Based on the known acute in vivo toxicity of DMTC, this experiment correctly placed this chemical in the GSH classification. No cytotoxic effects were observed at any of in vitro lower concentrations, as all cell viability measurements remained above 75% relative to vehicle controls.

Conclusions: These findings indicate that, despite high toxicity of the tested chemicals, the levels of DMTC and MBT-1 expected in occupational settings (similar to what people might be exposed to at work) do not pose a significant risk to human respiratory health. A novel approach to correlate in vitro concentration range (in concentrations preprepared in liquid vehicle) to real in vivo air concentration in the working breathing zone was used in this study. Additional studies with the air pollutant of other GHS categories are needed to confirm a validity of this approach.

Abstract

Background and Purpose: IS-001 and IS-002 are imaging agents to visualize the ureter and Prostate Specific Membrane Antigen (PSMA) in prostate tumors (respectively) during robot-assisted surgical procedures. These compounds are now in clinical trials.

Methods: The skin and eye irritation of IS-001 and IS-002 were studied in reconstructed human epidermis and cornea-like epithelial human tissues using MatTEk EpiSkin and EPiOcular kits, respectively.

Results: Both agents have a strong green color. This presented a challenge and potential interference with measuring the final blue color read of the MTT cell viability assays. Several additional tests for potential color interference were performed in both skin and eye irritation assays. The cell viability following imaging agent incubation with the killed and alive skin and eye tissues was measured and compared. All acceptance criteria with all necessary positive and negative controls were met for both skin and eye assays confirming the validity of these in vitro human tissue assays. The final cell viability in the EPiOcular assay after subtraction of the interferences of the killed tissue and colored control were 87.1% and 82.0% for IS-001 and IS-002, respectively. According to the OECD TG432 Guidelines, the viability above 60% confirms that the tested agent is not an irritant and does not require classification and labeling for eye irritation or serious eye damage. Similarly, after adjustment of the potential color interference of the agents incubated with the skin tissue, the final viability was 81.9% and 91.0% for IS-001 and IS-002, respectively. According to the OECD TG439 Guidelines, compounds with viability above 50% are not considered irritants and do not require irritation labeling.

Conclusions: Based on the obtained in vitro data, both IS-001 and IS-002 are not considered irritants for either skin or eye, and no irritation categories are assigned to these compounds.

Summary

We develop patient-derived organoid (PDO) models that represent the large spectrum of patient tumors. We describe here a breast cancer organoid model that is HER2 and progesterone negative and estrogen receptor positive that we use to test and estimate the IC50 values of the various known and novel drugs. In separate experiments we administered the drugs for 2, 3 or 4 days. A Glow 3D ATP assay was used to assess cell viability post treatment with drug. The size and condition of the organoids were monitored daily by phase contrast microscopy prior to and during the cytotoxicity assays. The assays were repeated at 2 or 3 different times in which either smaller or larger sized organoids were tested. We observe that the IC50 of Doxorubicin (DOX) was about 5-fold lower than Taxol (TAX) when smaller sized organoids were tested. This correlates well with the clinical standard practice where Taxol is used at several-fold higher doses compared to DOX. As expected, Anastrozole (an aromatase inhibitor that converts testosterone into the estrogen) that was used as a negative control, did not show any cytotoxicity. In the subsequent experiments we tested the same drugs and additional known and novel drugs at 9 concentrations per drug. The nano-formulated DOX showed exactly the same cytotoxic activity as DOX alone. Fulvestrant (an estrogen inhibitor) showed little or no cytotoxic activity. A novel antibody-drug conjugate (ADC) also showed low cytotoxic activity despite the fact the cells expressed the target molecule and tumor inhibition was observed in vivo in xenografts reflecting that either higher concentrations were needed in vitro or that additional immune components such as engineered T cells and macrophages may enhance the in vitro activity of this ADC. Our comparative study with various known and novel drugs reveal that organoids can be used for screening libraries of drugs and anti-cancer biologicals. The ability to derive PDO’s from patient tumors and the availability of a large array of PDO’s that represent the several classes and subtypes of cancers will enhance both drug development and will be key in personalized medicine and is our quest.