Arginase 1/2 Inhibitor OATD-02: From Discovery to First-in-man Setup in Cancer Immunotherapy.

Pharmacologic inhibition of the controlling immunity pathway enzymes arginases 1 and 2 (ARG1 and ARG2) is a promising strategy for cancer immunotherapy. Here, we report the discovery and development of OATD-02, an orally bioavailable, potent arginases inhibitor. The unique pharmacologic properties of OATD-02 are evidenced by targeting intracellular ARG1 and ARG2, as well as long drug-target residence time, moderate to high volume of distribution, and low clearance, which may jointly provide a weapon against arginase-related tumor immunosuppression and ARG2-dependent tumor cell growth. OATD-02 monotherapy had an antitumor effect in multiple tumor models and enhanced an efficacy of the other immunomodulators. Completed nonclinical studies and human pharmacokinetic predictions indicate a feasible therapeutic window and allow for proposing a dose range for the first-in-human clinical study in patients with cancer. SIGNIFICANCE: We have developed an orally available, small-molecule intracellular arginase 1 and 2 inhibitor as a potential enhancer in cancer immunotherapy. Because of its favorable pharmacologic properties shown in nonclinical studies, OATD-02 abolishes tumor immunosuppression induced by both arginases, making it a promising drug candidate entering clinical trials.

Open-label, single-center, phase I trial to investigate the mass balance and absolute bioavailability of the highly selective oral MET inhibitor tepotinib in healthy volunteers.

Tepotinib (MSC2156119J) is an oral, potent, highly selective MET inhibitor. This open-label, phase I study in healthy volunteers (EudraCT 2013-003226-86) investigated its mass balance (part A) and absolute bioavailability (part B). In part A, six participants received tepotinib orally (498 mg spiked with 2.67 MBq [14C]-tepotinib). Blood, plasma, urine, and feces were collected up to day 25 or until excretion of radioactivity was <1% of the administered dose. In part B, six participants received 500 mg tepotinib orally as a film-coated tablet, followed by an intravenous [14C]-tepotinib tracer dose (53-54 kBq) 4 h later. Blood samples were collected until day 14. In part A, a median of 92.5% (range, 87.1-96.9%) of the [14C]-tepotinib dose was recovered in excreta. Radioactivity was mainly excreted via feces (median, 78.7%; range, 69.4-82.5%). Urinary excretion was a minor route of elimination (median, 14.4% [8.8-17.7%]). Parent compound was the main constituent in excreta (45% [feces] and 7% [urine] of the radioactive dose). M506 was the only major metabolite. In part B, absolute bioavailability was 72% (range, 62-81%) after oral administration of 500 mg tablets (the dose and formulation used in phase II trials). In conclusion, tepotinib and its metabolites are mainly excreted via feces; parent drug is the major eliminated constituent. Oral bioavailability of tepotinib is high, supporting the use of the current tablet formulation in clinical trials. Tepotinib was well tolerated in this study with healthy volunteers.

Discovery of Evobrutinib: An Oral, Potent, and Highly Selective, Covalent Bruton's Tyrosine Kinase (BTK) Inhibitor for the Treatment of Immunological Diseases.

Bruton's tyrosine kinase (BTK) inhibitors such as ibrutinib hold a prominent role in the treatment of B cell malignancies. However, further refinement is needed to this class of agents, particularly in terms of adverse events (potentially driven by kinase promiscuity), which preclude their evaluation in nononcology indications. Here, we report the discovery and preclinical characterization of evobrutinib, a potent, obligate covalent inhibitor with high kinase selectivity. Evobrutinib displayed sufficient preclinical pharmacokinetic and pharmacodynamic characteristics which allowed for in vivo evaluation in efficacy models. Moreover, the high selectivity of evobrutinib for BTK over epidermal growth factor receptor and other Tec family kinases suggested a low potential for off-target related adverse effects. Clinical investigation of evobrutinib is ongoing in several autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus.

Identification and optimization of pyridazinones as potent and selective c-Met kinase inhibitors.

In a high-throughput screening campaign for c-Met kinase inhibitors, a thiadiazinone derivative with a carbamate group was identified as a potent in vitro inhibitor. Subsequent optimization guided by c-Met-inhibitor X-ray structures furnished new compound classes with excellent in vitro and in vivo profiles. The thiadiazinone ring of the HTS hit was first replaced by a pyridazinone followed by an exchange of the carbamate hinge binder with a 1,5-disubstituted pyrimidine. Finally an optimized compound, 22 (MSC2156119), with excellent in vitro potency, high kinase selectivity, long half-life after oral administration and in vivo anti-tumor efficacy at low doses, was selected as a candidate for clinical development.

A novel strategy for ADME screening of prodrugs: combined use of serum and hepatocytes to integrate bioactivation and clearance, and predict exposure to both active and prodrug to the systemic circulation.

Common strategies to optimize prodrugs use either in vitro or rodent in vivo approaches, which do not consider elimination pathways that do not result in the generation of the desired product or might be misleading because of species differences, respectively. As a step forward, we have incorporated a novel application of hepatocytes into our prodrug optimization strategy to increase the bioavailability of a poorly soluble drug candidate by attaching a charged ester linker. The model involves the incubation of hepatocytes from multiple species in serum-containing medium to mimic formation as well as simultaneous metabolism of both prodrug and active drug. Using this strategy, a correlation between the in vitro AUC and the AUC after intravenous administration was obtained for active drug formation in several species. Moreover, hepatocytes correctly predicted the likelihood of undesired exposure with nonhydrolyzed prodrug. This novel approach enabled us to identify several prodrugs, which showed improved exposure over a wide dose range. Furthermore, a strategy was developed resulting in a decision tree that can be used to determine the applicability of the hepatocyte model in the screening process.

EMD 1214063 and EMD 1204831 constitute a new class of potent and highly selective c-Met inhibitors.

PURPOSE: The mesenchymal-epithelial transition factor (c-Met) receptor, also known as hepatocyte growth factor receptor (HGFR), controls morphogenesis, a process that is physiologically required for embryonic development and tissue repair. Aberrant c-Met activation is associated with a variety of human malignancies including cancers of the lung, kidney, stomach, liver, and brain. In this study, we investigated the properties of two novel compounds developed to selectively inhibit the c-Met receptor in antitumor therapeutic interventions. EXPERIMENTAL DESIGN: The pharmacologic properties, c-Met inhibitory activity, and antitumor effects of EMD 1214063 and EMD 1204831 were investigated in vitro and in vivo, using human cancer cell lines and mouse xenograft models. RESULTS: EMD 1214063 and EMD 1204831 selectively suppressed the c-Met receptor tyrosine kinase activity. Their inhibitory activity was potent [inhibitory 50% concentration (IC50), 3 nmol/L and 9 nmol/L, respectively] and highly selective, when compared with their effect on a panel of 242 human kinases. Both EMD 1214063 and EMD 1204831 inhibited c-Met phosphorylation and downstream signaling in a dose-dependent fashion, but differed in the duration of their inhibitory activity. In murine xenograft models, both compounds induced regression of human tumors, regardless of whether c-Met activation was HGF dependent or independent. Both drugs were well tolerated and induced no substantial weight loss after more than 3 weeks of treatment. CONCLUSIONS: Our results indicate selective c-Met inhibition by EMD 1214063 and EMD 1204831 and strongly support clinical testing of these compounds in the context of molecularly targeted anticancer strategies.

The αVß3/αVß5 integrin inhibitor cilengitide augments tumor response to melphalan isolated limb perfusion in a sarcoma model.

Isolated limb perfusion (ILP) with melphalan and tumor necrosis factor (TNF)-α is used to treat bulky, locally advanced melanoma and sarcoma. However, TNF toxicity suggests a need for better-tolerated drugs. Cilengitide (EMD 121974), a novel cyclic inhibitor of alpha-V integrins, has both anti-angiogenic and direct anti-tumor effects and is a possible alternative to TNF in ILP. In this study, rats bearing a hind limb soft tissue sarcoma underwent ILP using different combinations of melphalan, TNF and cilengitide in the perfusate. Further groups had intra-peritoneal (i.p.) injections of cilengitide or saline 2 hr before and 3 hr after ILP. A 77% response rate (RR) was seen in animals treated i.p. with cilengitide and perfused with melphalan plus cilengitide. The RR was 85% in animals treated i.p. with cilengitide and ILP using melphalan plus both TNF and cilengitide. Both RRs were significantly greater than those seen with melphalan or cilengitide alone. Histopathology showed that high RRs were accompanied by disruption of tumor vascular endothelium and tumor necrosis. Compared with ILP using melphalan alone, the addition of cilengitide resulted in a three to sevenfold increase in melphalan concentration in tumor but not in muscle in the perfused limb. Supportive in vitro studies indicate that cilengitide both inhibits tumor cell attachment and increases endothelial permeability. Since cilengitide has low toxicity, these data suggest the agent is a good alternative to TNF in the ILP setting.

In vitro biotransformation of (R)- and (S)-thalidomide: application of circular dichroism spectroscopy to the stereochemical characterization of the hydroxylated metabolites.

Circular dichroism (CD) spectroscopy was successfully used for the stereochemical characterization of the hydroxylated metabolites formed during the in vitro biotransformation of (R)- and (S)-thalidomide. Incubation extracts of the individual enantiomers were analyzed by HPLC on an achiral stationary phase combined with CD detection. The CD data of the almost enantiopure eluates of the metabolites were compared with the CD spectra quantum chemically calculated for the respective structures. The results allowed us a reliable determination of the absolute stereostructure for all of the metabolites. The chiral center of thalidomide is unaffected by the stereoselective biotransformation process. (3'R,5'R)-trans-5'-hydroxythalidomide is the main metabolite of (R)-thalidomide, which epimerizes spontaneously to give the more stable (3'S,5'R)-cis isomer. On the contrary, (S)-thalidomide is preferentially metabolized by hydroxylation in the phthalimide moiety, resulting in the formation of (S)-5-hydroxythalidomide.