The multi cellular tumor spheroid (MCTS) model has been used for decades with proven superiority over monolayer cell culture models at recapitulating in vivo tumor growth. Yet its use in high-throughput drug discovery has been limited, particularly with image based screening, due to practical and technical hurdles. Here we report a significant advance in utilizing live MCTS models for high-content image based drug discovery. Using a validated GFP reporter (CK5Pro-GFP) of luminal breast cancer stem cells (CSC), we developed an algorithm to quantify changes in CK5Pro-GFP expression levels for individual Z-stack planes (local) or as maximal projections of the summed Z-stacks (global) of MCTS. From these image sets, we can quantify the cross-sectional area of GFP positive cells, the fluorescence intensity of the GFP positive cells, and the percent of spheroid cross-sectional area that expresses CK5Pro-GFP.We demonstrate that acquiring data in this manner can be done in real time and is statistically robust (Z’=0.85) for use in primary high-content screening cancer drug discovery.

Antibody-drug conjugates (ADCs) combine highly specific monoclonal antibodies with potent cytotoxic drugs. Their synergy allows for targeted delivery of toxic drugs to cancer cells while sparing systemic exposure. In this review, we focus on the history and clinical applications of ADCs approved by the U.S. Food and Drug Administration (FDA) for the treatment of cancer and highlight new ADCs in the drug development pipeline. Three ADCs have received FDA approval thus far. Gemtuzumab ozogamicin, although withdrawn from the U.S. market, may still be an effective treatment modality in subsets of patients with acute myeloid leukemia. Brentuximab vedotin and ado-trastuzumab emtansine have shown improved efficacy and safety data compared with standard chemotherapy for the treatment of advanced lymphoma and breast cancer, respectively. With a number of ADCs with promising preliminary data in the clinical trial pipeline, cancer therapy is moving forward from traditional chemotherapy to targeted treatment modalities driven by the specificity of monoclonal antibodies and advancing biotechnology.

Identification of dopamine D3 receptors (D3R) in vivo is important to understand several brain functions related to addiction. The goal of this work was to identify D3R binding of the dopamine D2 receptor (D2R)/D3R imaging agent, 18F-fallypride. Brain slices from male Sprague-Dawley rats (n=6) and New Zealand White rabbits (n=6) were incubated with 18F-fallypride and D3R selective agonist (R)-7-OH-DPAT (98-fold D3R selective). Rat slices were also treated with BP 897 (68-fold D3R selective partial agonist) and NGB 2904 (56-fold D3R selective antagonist). In vivo rat studies (n=6) were done on Inveon PET using 18–37 MBq 18F-fallypride and drug-induced displacement by (R)-7-OH-DPAT, BP 897 and NGB 2904. PET/CT imaging of wild type (WT, n=2) and D2R knock-out (KO, n=2) mice were carried out with 18F-fallypride. (R)-7-OH-DPAT displaced binding of 18F-fallypride, both in vitro and in vivo. In vitro, at 10 nM (R)-7-OH-DPAT, 18F-fallypride binding in the rat ventral striatum (VST) and dorsal striatum (DST) and rabbit nucleus accumbens were reduced by ~10–15%. At 10 µM (R)-7-OH-DPAT all regions in rat and rabbit were reduced by ≥85%. In vivo reductions for DST and VST before and after (R)-7-OH-DPAT were: low-dose (0.015mg/kg) DST −22%, VST −29%; high-dose (1.88 mg/kg) DST −58%, VST −77%, suggesting D3R/D2R displacement. BP 897 and NGB 2904 competed with 18F-fallypride in vitro, but unlike BP 897, NGB2904 did not displace 18F-fallypride in vivo. The D2R KO mice lacked 18F-fallypride binding in the DST. In summary, our findings suggest that up to 20% of 18F-fallypride may be bound to D3R sites in vivo.