UNC5293, a potent, orally available and highly MERTK-selective inhibitor.

Inhibition of MER receptor tyrosine kinase (MERTK) causes direct tumor cell killing and stimulation of the innate immune response. Therefore, MERTK has been identified as a therapeutic target in a wide variety of human tumors. Clinical trials targeting MERTK have recently been initiated, however, none of these drugs are MERTK-specific. Herein, we present the discovery of a highly MERTK-selective inhibitor UNC5293 (24). UNC5293 has subnanomolar activity against MERTK with an excellent Ambit selectivity score (S50 (100 nM) = 0.041). It mediated potent and selective inhibition of MERTK in cell-based assays. Furthermore, it has excellent mouse PK properties (7.8 h half-life and 58% oral bioavailability) and was active in bone marrow leukemia cells in a murine model.

Discovery and Optimization of 2H-1λ2-Pyridin-2-one Inhibitors of Mutant Isocitrate Dehydrogenase 1 for the Treatment of Cancer.

Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are oncogenic for a number of malignancies, primarily low-grade gliomas and acute myeloid leukemia. We report a medicinal chemistry campaign around a 7,7-dimethyl-7,8-dihydro-2H-1λ2-quinoline-2,5(6H)-dione screening hit against the R132H and R132C mutant forms of isocitrate dehydrogenase (IDH1). Systematic SAR efforts produced a series of potent pyrid-2-one mIDH1 inhibitors, including the atropisomer (+)-119 (NCATS-SM5637, NSC 791985). In an engineered mIDH1-U87-xenograft mouse model, after a single oral dose of 30 mg/kg, 16 h post dose, between 16 and 48 h, (+)-119 showed higher tumoral concentrations that corresponded to lower 2-HG concentrations, when compared with the approved drug AG-120 (ivosidenib).

Isosteres of ester derived glucose uptake inhibitors.

Glucose transporters (GLUTs) facilitate glucose uptake and are overexpressed in most cancer cells. Inhibition of glucose transport has been shown to be an effective method to slow the growth of cancer cells both in vitro and in vivo. We have previously reported on the anticancer activity of an ester derived glucose uptake inhibitor. Due to the hydrolytic instability of the ester linkage we have prepared a series of isosteres of the ester moiety. Of all of the isosteres prepared, the amine linkage showed the most promise. Several additional analogues of the amine-linked compounds were also prepared to improve the overall activity.

Reduced sarcolemmal aquaporin 4 expression can support the differential diagnosis of neuromyelitis optica spectrum disorders.

This study aimed to investigate the underlying pathological muscle damage in neuromyelitis optica spectrum disorder (NMOSD) patients without muscular symptoms. We prospectively enrolled 15 patients with aquaporin 4 (AQP4) antibody seropositive NMOSD and 16 patients with non-NMOSD diseases as a control group. Biceps biopsy samples from 18 patients were examined. Six NMOSD patients exhibited inflammatory lesions/edema in lower muscles on muscle MRI. On histopathological examination, NMOSD samples showed significantly decreased IgG-targeting AQP4 expression on sarcolemma compared with non-NMOSD samples in terms of the area of positive staining and integrated optical density. Muscle biopsy can support the differential diagnosis of NMOSD.

Kinome profiling of non-Hodgkin lymphoma identifies Tyro3 as a therapeutic target in primary effusion lymphoma.

Non-Hodgkin lymphomas (NHLs) make up the majority of lymphoma diagnoses and represent a very diverse set of malignancies. We sought to identify kinases uniquely up-regulated in different NHL subtypes. Using multiplexed inhibitor bead-mass spectrometry (MIB/MS), we found Tyro3 was uniquely up-regulated and important for cell survival in primary effusion lymphoma (PEL), which is a viral lymphoma infected with Kaposi's sarcoma-associated herpesvirus (KSHV). Tyro3 was also highly expressed in PEL cell lines as well as in primary PEL exudates. Based on this discovery, we developed an inhibitor against Tyro3 named UNC3810A, which hindered cell growth in PEL, but not in other NHL subtypes where Tyro3 was not highly expressed. UNC3810A also significantly inhibited tumor progression in a PEL xenograft mouse model that was not seen in a non-PEL NHL model. Taken together, our data suggest Tyro3 is a therapeutic target for PEL.

Highly Selective MERTK Inhibitors Achieved by a Single Methyl Group.

Although all kinases share the same ATP binding pocket, subtle differences in the residues that form the pocket differentiate individual kinases' affinity for ATP competitive inhibitors. We have found that by introducing a single methyl group, the selectivity of our MERTK inhibitors over another target, FLT3, was increased up to 1000-fold (compound 31). Compound 19 was identified as an in vivo tool compound with subnanomolar activity against MERTK and 38-fold selectivity over FLT3 in vitro. The potency and selectivity of 19 for MERTK over FLT3 were confirmed in cell-based assays using human cancer cell lines. Compound 19 had favorable pharmacokinetic properties in mice. Phosphorylation of MERTK was decreased by 75% in bone marrow leukemia cells from mice treated with 19 compared to vehicle-treated mice.

Early identification of anti-NMDA receptor encephalitis presenting cerebral lesions in unconventional locations on magnetic resonance imaging.

To facilitate the diagnosis of anti-NMDAR encephalitis presenting with brain lesions in unconventional locations (BLUL) on MRI, we retrospectively analyzed forty-five Chinese patients. Eighteen (40.0%) of their MRI initially exhibited one or more BLUL. These locations predominantly included cerebral gray matter (cortex, basal ganglia and thalamus), as well as white matter and brainstem. Due to these BLUL, thirteen (72.2%) patients were originally misdiagnosed with other diseases and developed poor clinical and imaging outcomes. Therefore, anti-NMDAR encephalitis has unpredictable MRI findings that easily obscure its diagnosis and cause serious sequelae. Anti-NMDAR antibody tests are highly recommended in patients with BLUL.

Discovery of Macrocyclic Pyrimidines as MerTK-Specific Inhibitors.

Macrocycles have attracted significant attention in drug discovery recently. In fact, a few de novo designed macrocyclic kinase inhibitors are currently in clinical trials with good potency and selectivity for their intended target. In this study, we successfully engaged a structure-based drug design approach to discover macrocyclic pyrimidines as potent Mer tyrosine kinase (MerTK)-specific inhibitors. An enzyme-linked immunosorbent assay (ELISA) in 384-well format was employed to evaluate the inhibitory activity of macrocycles in a cell-based assay assessing tyrosine phosphorylation of MerTK. Through structure-activity relationship (SAR) studies, analogue 11 [UNC2541; (S)-7-amino-N-(4-fluorobenzyl)-8-oxo-2,9,16-triaza-1(2,4)-pyrimidinacyclohexadecaphane-1-carboxamide] was identified as a potent and MerTK-specific inhibitor that exhibits sub-micromolar inhibitory activity in the cell-based ELISA. In addition, an X-ray structure of MerTK protein in complex with 11 was resolved to show that these macrocycles bind in the MerTK ATP pocket.

UNC2025, a MERTK Small-Molecule Inhibitor, Is Therapeutically Effective Alone and in Combination with Methotrexate in Leukemia Models.

Purpose: MERTK tyrosine kinase is ectopically expressed in 30% to 50% of acute lymphoblastic leukemias (ALL) and more than 80% of acute myeloid leukemias (AML) and is a potential therapeutic target. Here, we evaluated the utility of UNC2025, a MERTK tyrosine kinase inhibitor, for treatment of acute leukemia.Experimental Design: Preclinical in vitro and in vivo assays using cell lines and primary leukemia patient samples were used to evaluate antileukemic effects of UNC2025.Results: UNC2025 potently inhibited prosurvival signaling, induced apoptosis, and reduced proliferation and colony formation in MERTK-expressing ALL and AML cell lines and patient samples. Approximately 30% of primary leukemia patient samples (78 of 261 total) were sensitive to UNC2025. Sensitive samples were most prevalent in the AML, T-ALL, and minimally differentiated (M0) AML subsets. UNC2025 inhibited MERTK in bone marrow leukemia cells and had significant therapeutic effects in xenograft models, with dose-dependent decreases in tumor burden and consistent two-fold increases in median survival, irrespective of starting disease burden. In a patient-derived AML xenograft model, treatment with UNC2025 induced disease regression. In addition, UNC2025 increased sensitivity to methotrexate in vivo, suggesting that addition of MERTK-targeted therapy to current cytotoxic regimens may be particularly effective and/or allow for chemotherapy dose reduction.Conclusions: The broad-spectrum activity mediated by UNC2025 in leukemia patient samples and xenograft models, alone or in combination with cytotoxic chemotherapy, supports continued development of MERTK inhibitors for treatment of leukemia. Clin Cancer Res; 23(6); 1481-92. ©2016 AACR.

Repeated misdiagnosis of a relapsed atypical anti-NMDA receptor encephalitis without an associated ovarian teratoma.

We present an atypical case of relapsed anti-NMDAR encephalitis in a young female patient without an associated ovarian teratoma. She presented with recurrent seizure attacks with muscle weakness, psychosis, dyskinesia, autonomic failure and insomnia. She was first misdiagnosed as mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) then Hashimoto's encephalopathy due to diffuse cerebral lesions, elevated serum lactic acid concentration, increased amount of thyroid peroxidase and thyroglobulin antibodies in serum and diffuse lesions of the thyroid gland. Her final diagnosis was delayed for 6 months with the detection of anti-NMDAR antibodies in her CSF. After treatment, she had poor recovery with serious sequelae at 10-month follow-up. Noteworthy, MELAS should be highlighted as a differential diagnosis of anti-NMDAR encephalitis.

Design and Synthesis of Novel Macrocyclic Mer Tyrosine Kinase Inhibitors.

Mer tyrosine kinase (MerTK) is aberrantly elevated in various tumor cells and has a normal anti-inflammatory role in the innate immune system. Inhibition of MerTK may provide dual effects against these MerTK-expressing tumors through reducing cancer cell survival and redirecting the innate immune response. Recently, we have designed novel and potent macrocyclic pyrrolopyrimidines as MerTK inhibitors using a structure-based approach. The most active macrocycles had an EC50 below 40 nM in a cell-based MerTK phosphor-protein ELISA assay. The X-ray structure of macrocyclic analogue 3 complexed with MerTK was also resolved and demonstrated macrocycles binding in the ATP binding pocket of the MerTK protein as anticipated. In addition, the lead compound 16 (UNC3133) had a 1.6 h half-life and 16% oral bioavailability in a mouse PK study.

Etiological, clinical, and radiological features of longitudinally extensive myelopathy in Chinese patients.

Longitudinally extensive myelopathy (LEM) is a rare spinal syndrome, and was mostly assessed in western populations. In order to investigate the etiological, clinical, and radiological features of LEM in Chinese patients, we retrospectively analyzed eighty-nine (40 men and 49 women, median age 45.9±15.7years) patients with LEM hospitalized in China-Japan Friendship Hospital. LEM comprised autoimmune inflammatory myelitis (n=53), metabolic and compressive disorders (n=13), vascular diseases (n=10), neoplastic diseases (n=7), infectious diseases (n=4), and syringomyelia (n=2). Neuromyelitis optica spectrum disorders (NMOSD) was the most common cause of transverse myelopathy identified in LEM (38/89 [42.7%]) characterized by intractable vomiting and hiccups and painful tonic spasms. Subacute combined degeneration and anterior spinal artery syndrome accounted for the largest non-transverse LEM, which selectively affected the spinal dorsal and/or lateral columns and the spinal anterior region, respectively. Radicular pain was common in anterior spinal artery syndrome. Postrema (n=15, 39.5%) and cervical (n=31, 81.6%) lesions were significantly increased in NMOSD versus non-NMOSD (n=7, 13.7% and n=34, 66.7%, respectively, p<0.05]. Axial T2-weighted MRI indicated that 46 (51.7%) patients exhibited complete lesions; 43 (48.3%) patients exhibited non-transverse lesions, mainly unilateral or symmetrical tract lesions. Twenty-four (51.1%) LEM patients exhibited distinct gadolinium contrast enhancement. In this Chinese cohort, LEM was primarily attributed to NMOSD. While the etiological distribution in the non-NMOSD group was different from western populations, clinical and imaging features may facilitate a differential diagnosis.

Optic nerve involvement in immunoglobulin G4-related disease: A case report.

The present study reports the case of a 79-year-old woman manifesting skin changes, a pancreatic neoplasm, enlarged lymph nodes, an eyelid mass and interstitial pneumonia over a 30-year period. At 2 months before admission to our hospital, the patient presented rapid vision loss in the left eye. Left optic nerve atrophy with a focal hyperintense lesion was documented on a T2-weighted magnetic resonance imaging (MRI) scan, and visual evoked potential implicit times were prolonged. Elevated serum immunoglobulin G4 (IgG4) concentrations and the presence of enriched IgG4-positive plasma cells in the lymph nodes established the diagnosis of IgG4-related optic neuropathy. Following oral treatment with methylprednisolone, the serum IgG4 levels fell to normal levels, and the left eye visual acuity improved to a level that remained stable over a 1-year follow-up period. After 4 months of methylprednisolone administration, the optic nerve appeared to be normal on an MRI scan. Prior reports on IgG4-related optic neuropathy involved an infiltrating mass, which was not observed in the present case. Similarly to the current study, previous cases have responded to treatment with glucocorticoids, indicating that the underlying mechanism of the disease may be common.

The MERTK/FLT3 inhibitor MRX-2843 overcomes resistance-conferring FLT3 mutations in acute myeloid leukemia.

FMS-like tyrosine kinase 3-targeted (FLT3-targeted) therapies have shown initial promise for the treatment of acute myeloid leukemia (AML) expressing FLT3-activating mutations; however, resistance emerges rapidly. Furthermore, limited options exist for the treatment of FLT3-independent AML, demonstrating the need for novel therapies that reduce toxicity and improve survival. MERTK receptor tyrosine kinase is overexpressed in 80% to 90% of AMLs and contributes to leukemogenesis. Here, we describe MRX-2843, a type 1 small-molecule tyrosine kinase inhibitor that abrogates activation of both MERTK and FLT3 and their downstream effectors. MRX-2843 treatment induces apoptosis and inhibits colony formation in AML cell lines and primary patient samples expressing MERTK and/or FLT3-ITD, with a wide therapeutic window compared with that of normal human cord blood cells. In murine orthotopic xenograft models, once-daily oral therapy prolonged survival 2- to 3-fold over that of vehicle-treated controls. Additionally, MRX-2843 retained activity against quizartinib-resistant FLT3-ITD-mutant proteins with clinically relevant alterations at the D835 or F691 loci and prolonged survival in xenograft models of quizartinib-resistant AML. Together, these observations validate MRX-2843 as a translational agent and support its clinical development for the treatment of AML.

Differentiation of neuromyelitis optica spectrum disorders from ultra-longitudinally extensive transverse myelitis in a cohort of Chinese patients.

This study aimed to differentiate neuromyelitis optica spectrum disorders (NMOSD) from other causes in cases of ultra-longitudinally extensive transverse myelitis (uLETM). We retrospectively analyzed thirty-three Chinese patients with uLETM hospitalized in the China-Japan Friendship Hospital. The patients were divided into NMOSD (n=21) and non-NMOSD (n=12) groups. The NMOSD group exhibited significantly more comorbidity compared with the non-NMOSD group; moreover, the NMOSD group uniquely exhibited intractable vomiting and hiccups (IVH). The prevalence rates of cervicothoracic, area postrema (AP), and other circumventricular organ (CVO) lesions were significantly increased in the NMOSD group compared with the non-NMOSD group. Moreover, uLETM was strongly associated with NMOSD. These novel findings indicate that CVO lesions, including AP, and particularly when combined with clinical IVH, may represent a useful discriminator to differentiate NMOSD.

Small Molecule Inhibition of MERTK Is Efficacious in Non-Small Cell Lung Cancer Models Independent of Driver Oncogene Status.

Treatment of non-small cell lung cancer (NSCLC) has been transformed by targeted therapies directed against molecular aberrations specifically activated within an individual patient's tumor. However, such therapies are currently only available against a small number of such aberrations, and new targets and therapeutics are needed. Our laboratory has previously identified the MERTK receptor tyrosine kinase (RTK) as a potential drug target in multiple cancer types, including NSCLC. We have recently developed UNC2025--the first-in-class small molecule inhibitor targeting MERTK with pharmacokinetic properties sufficient for clinical translation. Here, we utilize this compound to further validate the important emerging biologic functions of MERTK in lung cancer pathogenesis, to establish that MERTK can be effectively targeted by a clinically translatable agent, and to demonstrate that inhibition of MERTK is a valid treatment strategy in a wide variety of NSCLC lines independent of their driver oncogene status, including in lines with an EGFR mutation, a KRAS/NRAS mutation, an RTK fusion, or another or unknown driver oncogene. Biochemically, we report the selectivity of UNC2025 for MERTK, and its inhibition of oncogenic downstream signaling. Functionally, we demonstrate that UNC2025 induces apoptosis of MERTK-dependent NSCLC cell lines, while decreasing colony formation in vitro and tumor xenograft growth in vivo in murine models. These findings provide further evidence for the importance of MERTK in NSCLC, and demonstrate that MERTK inhibition by UNC2025 is a feasible, clinically relevant treatment strategy in a wide variety of NSCLC subtypes, which warrants further investigation in clinical trials.

Efficacy of a Mer and Flt3 tyrosine kinase small molecule inhibitor, UNC1666, in acute myeloid leukemia.

Mer and Flt3 receptor tyrosine kinases have been implicated as therapeutic targets in acute myeloid leukemia (AML). In this manuscript we describe UNC1666, a novel ATP-competitive small molecule tyrosine kinase inhibitor, which potently diminishes Mer and Flt3 phosphorylation in AML. Treatment with UNC1666 mediated biochemical and functional effects in AML cell lines expressing Mer or Flt3 internal tandem duplication (ITD), including decreased phosphorylation of Mer, Flt3 and downstream effectors Stat, Akt and Erk, induction of apoptosis in up to 98% of cells, and reduction of colony formation by greater than 90%, compared to treatment with vehicle. These effects were dose-dependent, with inhibition of downstream signaling and functional effects correlating with the degree of Mer or Flt3 kinase inhibition. Treatment of primary AML patient samples expressing Mer and/or Flt3-ITD with UNC1666 also inhibited Mer and Flt3 intracellular signaling, induced apoptosis, and inhibited colony formation. In summary, UNC1666 is a novel potent small molecule tyrosine kinase inhibitor that decreases oncogenic signaling and myeloblast survival, thereby validating dual Mer/Flt3 inhibition as an attractive treatment strategy for AML.

UNC2025, a potent and orally bioavailable MER/FLT3 dual inhibitor.

We previously reported a potent small molecule Mer tyrosine kinase inhibitor UNC1062. However, its poor PK properties prevented further assessment in vivo. We report here the sequential modification of UNC1062 to address DMPK properties and yield a new potent and highly orally bioavailable Mer inhibitor, 11, capable of inhibiting Mer phosphorylation in vivo, following oral dosing as demonstrated by pharmaco-dynamic (PD) studies examining phospho-Mer in leukemic blasts from mouse bone marrow. Kinome profiling versus more than 300 kinases in vitro and cellular selectivity assessments demonstrate that 11 has similar subnanomolar activity against Flt3, an additional important target in acute myelogenous leukemia (AML), with pharmacologically useful selectivity versus other kinases examined.

[Analysis of clinical features for 8 patients with autoimmune dementia].

OBJECTIVE: To explore the clinical features and therapeutic profiles of autoimmune dementia. METHODS: Eight hospitalized patients with autoimmune dementia during March 2011 and May 2013 were recruited and retrospectively analyzed for clinical features, as well as therapeutic and prognosis profiles. RESULTS: There were 3 males and 5 females with a onset age range of 45-72 years. Their onsets varied from acute (n = 3), subacute (n = 1) to chronic (n = 4).Six of them had a fluctuating course. The diagnoses were multiple sclerosis (n = 3), paraneoplastic limbic encephalitis (n = 2) and Hashimoto's encephalopathy (n = 1), microscopic polyangiitis (n = 1) and unclassified autoimmune encephalopathy (n = 1). Progressive memory loss without delirium was the main symptom.In addition, 3 patients suffered epilepsy, 2 with intractable hyponatremia, 4 with positive serum autoimmune or paraneoplastic antibodies, 7 with inflammatory cerebrospinal fluid, 4 with abnormal electroencephalography (EEG) and 8 with various changes on brain magnetic resonance imaging (MRI). Two patients had concurrent Hashimoto's thyroiditis and another with small cell lung cancer. All patients improved after treatment with immunological and antineoplastic therapies. CONCLUSION: Autoimmune dementia has complex causes with a rapidly progressive and fluctuating course. The coexisting conditions include epilepsy, hyponatremia, organ-specific autoimmunity, inflammatory spinal fluid with abnormal EEG and brain MRI findings.Immunotherapy is recommended.

[Longitudinally extensive spinal cord lesion: etiology and imaging features].

OBJECTIVE: To explore the etiologies and imaging features of longitudinally extensive spinal cord lesion (LESCL). METHODS: The etiologies and magnetic resonance (MR) imaging features of 51 hospitalized LESCL patients from January 2011 to August 2013 were reviewed and retrospectively analyzed. RESULTS: Among them, the causes were neuromyelitis optica spectrum disorder (NMOSD, n = 25), isolated longitudinally extensive transverse myelitis (n = 6), subacute combined degeneration (n = 4), multiple sclerosis (MS, n = 3), paraneoplastic myelopathy (n = 3), anterior spinal artery syndrome (n = 3), acute disseminated encephalomyelitis (n = 2), spinal dural arteriovenous fistula (n = 2), intramedullary spinal cord metastasis (n = 1), myelopathic leukemia (n = 1) and syringomyelus (n = 1). For MR imaging, at least one lesion of each patient presented continuously longitudinal profile and whole-length spinal cord was involved in 11 patients. CONCLUSION: LESCL may be caused by various diseases. And the imaging features may aid its diagnosis despite a lack of specificity.