Evaluation of Tumor Response to Targeted Therapies in Precision-Cut Slices of Human Pancreatic Neuroendocrine Tumors

Tube dilution studies concerned with Thiostrepton were performed on a series of strains of each of the following species of microorganisms: various nonhemolytic streptococci (twelve strains), hemolytic streptococci (ten strains), Staphylococcus aureus (ten strains), Staphylococcus albus (ten strains), and seventeen other selected microorganisms.Tube dilution studies with Thiostrepton against the above-mentioned organisms indicated a marked inhibitory capacity of this antibiotic in extremely low concentration against sensitive microorganisms. The minimum inhibitory concentration of Thiostrepton against the various microorganisms studied after twenty-four hours was as follows: For Staphylococcus aureus, a range of 0.0300 mcg. to 0.0035 mcg. per milliliter, with a median of 0.0150 mcg. per milliliter; for Staphylococcus albus, a range of 0.0625 mcg. to 0.0156 mcg. per milliliter, with a median of 0.0312 mcg. per milliliter; for Streptococcus pyogenes Group A, a range of 0.1250 mcg. to 0.0019 mcg. per milliliter, with a median of 0.0039 to 0.0156 mcg. per milliliter; for nonhemolytic streptococci—Streptococcus faecalis (five strains), a range of 0.5000 mcg. to 0.0078 mcg. per milliliter, with a median of 0.0156 mcg. per milliliter; for Streptococcus mitis (five strains), a range of 0.5000 mcg. to 0.0156 mcg. per milliliter, with a median of 0.0250 mcg. per milliliter; for Streptococcus salivarius (two strains), a range of 1.0000 mcg. per milliliter for one organism and 0.0125 mcg. per milliliter for the other.Eighteen other microorganisms tested, including three E. coli, five A. aerogenes, four salmonella species, four proteus species, one Pseudomonas aeruginosa, and one Mycobacterium phlei were resistant to Thiostrepton in a concentration of one mcg. per milliliter.Five organisms, including one each of pneumococcus Type 1, pneumococcus Type 2, pneumococcus Type 3, Neisseria catarrhalis, and Corynebacterium xerose, were found highly sensitive to Thiostrepton.Further laboratory and clinical studies with Thiostrepton are indicated.