Malignant lymphoma with middle ear involvement in a Sprague-Dawley rat.

Sprague-Dawley rats are amongst the most widely used animals in biomedical research and malignant lymphoma has long been known to be a frequent neoplasm in these animals. A 9-month-old male control Sprague-Dawley rat from a toxicity study showed gelatinous material in the cranial cavity and dark, thickened cerebral meninges at necropsy. At microscopic evaluation of the temporal bone, neoplastic lymphocytes were seen invading several structures of the middle ear. The neoplastic cells appeared to extend from the marrow of the temporal bone, covered the dorsal part of the tympanic cavity wall, and surrounded and infiltrated the base of the tensor tympani muscle as well as the chorda tympani branch of the facial nerve. The lymphoma was generalized; neoplastic lymphocytes were also noted in numerous other tissues. Literature regarding neoplasms of the middle and inner ear in animals is scarce and, to our knowledge, this is the first report of a lymphoma involving the middle ear of a rat.

Optimization of the potency and pharmacokinetic properties of a macrocyclic ghrelin receptor agonist (Part I): Development of ulimorelin (TZP-101) from hit to clinic.

High-throughput screening of Tranzyme Pharma's proprietary macrocycle library using the aequorin Ca2+-bioluminescence assay against the human ghrelin receptor (GRLN) led to the discovery of novel agonists against this G-protein coupled receptor. Early hits such as 1 (Ki=86 nM, EC50=134 nM) though potent in vitro displayed poor pharmacokinetic properties that required optimization. While such macrocycles are not fully rule-of-five compliant, principally due to their molecular weight and clogP, optimization of their pharmacokinetic properties proved feasible largely through conformational rigidification. Extensive SAR led to the identification of 2 (Ki=16 nM, EC50=29 nM), also known as ulimorelin or TZP-101, which has progressed to phase III human clinical trials for the treatment of postoperative ileus. X-ray structure and detailed NMR studies indicated a rigid peptidomimetic portion in 2 that is best defined as a nonideal type-I' ß-turn. Compound 2 is 24% orally bioavailable in both rats and monkeys. Despite its potency, in vitro and in gastric emptying studies, 2 did not induce growth hormone (GH) release in rats, thus demarcating the GH versus GI pharmacology of GRLN.

Efficient parallel synthesis of macrocyclic peptidomimetics.

A new method for solid phase parallel synthesis of chemically and conformationally diverse macrocyclic peptidomimetics is reported. A key feature of the method is access to broad chemical and conformational diversity. Synthesis and mechanistic studies on the macrocyclization step are reported.

Discovery of a new class of macrocyclic antagonists to the human motilin receptor.

A novel class of macrocyclic peptidomimetics was identified and optimized as potent antagonists to the human motilin receptor (hMOT-R). Well-defined structure-activity relationships allowed for rapid optimization of potency that eventually led to high affinity antagonists to hMOT-R. Potency and antagonist functional activity were confirmed both in functional and cell-based assays, as well as on isolated rabbit intestinal smooth muscle strips. Rapid access to this novel class of macrocyclic target structures was made possible through two efficient and complementary solid-phase parallel synthetic approaches, both of which are reported herein.