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SHP2 is a nonreceptor protein tyrosine phosphatase encoded by the PTPN11 gene and is involved in cell growth and differentiation via the MAPK signaling pathway. SHP2 also plays an important role in the programed cell death pathway (PD-1/PD-L1). As an oncoprotein as well as a potential immunomodulator, controlling SHP2 activity is of high therapeutic interest. As part of our comprehensive program targeting SHP2, we identified multiple allosteric binding modes of inhibition and optimized numerous chemical scaffolds in parallel. In this drug annotation report, we detail the identification and optimization of the pyrazine class of allosteric SHP2 inhibitors. Structure and property based drug design enabled the identification of protein-ligand interactions, potent cellular inhibition, control of physicochemical, pharmaceutical and selectivity properties, and potent in vivo antitumor activity. These studies culminated in the discovery of TNO155, (3 S ,4 S )-8-(6-amino-5-((2-amino-3-chloropyridin-4-yl)thio)pyrazin-2-yl)-3-methyl-2-oxa-8-azaspiro[4.5]decan-4-amine ( 1 ), a highly potent, selective, orally efficacious, and first-in-class SHP2 inhibitor currently in clinical trials for cancer.

Background: Blastic plasmacytoid dendritic-cell neoplasm (BPDCN) is an aggressive hematologic cancer that is caused by transformed plasmacytoid dendritic cells that overexpress interleukin-3 receptor subunit alpha (IL3RA or CD123). Tagraxofusp (SL-401) is a CD123-directed cytotoxin consisting of human interleukin-3 fused to truncated diphtheria toxin., Methods: In this open-label, multicohort study, we assigned 47 patients with untreated or relapsed BPDCN to receive an intravenous infusion of tagraxofusp at a dose of 7 μg or 12 μg per kilogram of body weight on days 1 to 5 of each 21-day cycle. Treatment continued until disease progression or unacceptable toxic effects. The primary outcome was the combined rate of complete response and clinical complete response among patients who had not received previous treatment for BPDCN. A secondary outcome was the duration of response., Results: Of the 47 patients, 32 were receiving tagraxofusp as first-line treatment and 15 had received previous treatment. The median age of the patients was 70 years (range, 22 to 84). Among the 29 previously untreated patients who received tagraxofusp at a dose of 12 μg per kilogram, the primary outcome occurred in 21 (72%), and the overall response rate was 90%; of these patients, 45% went on to undergo stem-cell transplantation. Survival rates at 18 and 24 months were 59% and 52%, respectively. Among the 15 previously treated patients, the response rate was 67%, and the median overall survival was 8.5 months. The most common adverse events were increased levels of alanine aminotransferase (64%) and aspartate aminotransferase (60%), hypoalbuminemia (55%), peripheral edema (51%), and thrombocytopenia (49%). Capillary leak syndrome was reported in 19% of the patients and was associated with one death in each of the dose subgroups., Conclusions: In adult patients with untreated or relapsed BPDCN, the use of tagraxofusp led to clinical responses. Serious adverse events included capillary leak syndrome; hepatic dysfunction and thrombocytopenia were common. (Funded by Stemline Therapeutics and the Leukemia and Lymphoma Society Therapy Acceleration Program; ClinicalTrials.gov number, NCT02113982.)., (Copyright © 2019 Massachusetts Medical Society.)

Protein tyrosine phosphatase SHP2 is an oncoprotein associated with cancer as well as a potential immune modulator because of its role in the programmed cell death PD-L1/PD-1 pathway. In the preceding manuscript, we described the optimization of a fused, bicyclic screening hit for potency, selectivity, and physicochemical properties in order to further expand the chemical diversity of allosteric SHP2 inhibitors. In this manuscript, we describe the further expansion of our approach, morphing the fused, bicyclic system into a novel monocyclic pyrimidinone scaffold through our understanding of SAR and use of structure-based design. These studies led to the identification of SHP394 (1), an orally efficacious inhibitor of SHP2, with high lipophilic efficiency, improved potency, and enhanced pharmacokinetic properties. We also report other pyrimidinone analogues with favorable pharmacokinetic and potency profiles. Overall, this work improves upon our previously described allosteric inhibitors and exemplifies and extends the range of permissible chemical templates that inhibit SHP2 via the allosteric mechanism.

The present study was conducted to determine the efficacy of novel flavonoid vicenin-2 (VCN-2), an active constituent of the medicinal herb Ocimum Sanctum Linn or Tulsi, as a single agent and in combination with docetaxel (DTL) in carcinoma of prostate (CaP). VCN-2 effectively induced anti-proliferative, anti-angiogenic and pro-apoptotic effect in CaP cells (PC-3, DU-145 and LNCaP) irrespective of their androgen responsiveness or p53 status. VCN-2 inhibited EGFR/Akt/mTOR/p70S6K pathway along with decreasing c-Myc, cyclin D1, cyclin B1, CDK4, PCNA and hTERT in vitro. VCN-2 reached a level of 2.6±0.3μmol/l in serum after oral administration in mice which reflected that VCN-2 is orally absorbed. The i.v. administration of docetaxel (DTL), current drug of choice in androgen-independent CaP, is associated with dose-limiting toxicities like febrile neutropenia which has lead to characterization of alternate routes of administration and potential combinatorial regimens. In this regard, VCN-2 in combination with DTL synergistically inhibited the growth of prostate tumors in vivo with a greater decrease in the levels of AR, pIGF1R, pAkt, PCNA, cyclin D1, Ki67, CD31, and increase in E-cadherin. VCN-2 has been investigated for radioprotection and anti-inflammatory properties. This is the first study on the anti-cancer effects of VCN-2. In conclusion, our investigations collectively provide strong evidence that VCN-2 is effective against CaP progression along with indicating that VCN-2 and DTL co-administration is more effective than either of the single agents in androgen-independent prostate cancer., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Purpose: Protein kinase C-alpha has been implicated in malignant transformation and proliferation. Based on in vivo superadditive interaction between the protein kinase C-alpha antisense oligonucleotide LY900003 (Affinitak, ISIS 3521) and cisplatin, we designed this phase I/II trial of LY900003 with cisplatin/gemcitabine., Experimental Design: The safety of the combination, as well as potential pharmacokinetic interactions, was evaluated in the phase I portion of the trial. The phase II portion evaluated the antitumor activity of the combination in previously untreated patients with stage IIIB/IV non-small-cell lung cancer (NSCLC)., Results: Seven patients received 18 cycles of the combination during the phase I portion. Dose-limiting toxicity was only observed in one of six evaluable patients (grade 3 fatigue). However, due to a relatively high frequency of thrombocytopenia, cisplatin 80 (mg/m2) and gemcitabine (1,000 mg/m2) were recommended for the phase II portion. Antitumor activity was observed in two patients (one with NSCLC and one with pancreatic carcinoma), and prolonged stabilization was observed in two others. No pharmacokinetic interactions occurred. In the phase II portion, 55 NSCLC patients received the combination at two gemcitabine doses [1,000 mg/m2, n=44 (original cohort); 1,250 mg/m2, n=11 (expanded cohort)]. Fourteen of 39 evaluable patients in the original cohort had a response rate (1 complete response and 13 partial responses; response, 36%), whereas 2 of 9 evaluable patients in the expanded cohort experienced partial response (combined response rate, 33%). The median time to treatment failure was 3.9 months, whereas the median time response to progression for the 48 patients with evaluable response was 4.4 months (confidence interval, 3.5-5.5 months). Intent to treat median survival time was 8.9 months. Forty-eight percent of the patients experienced catheter-related events., Conclusions: LY900003 can be administered safely in combination with cisplatin and gemcitabine and is associated with antitumor activity in patients with advanced NSCLC. Better characterization of subsets of patients most likely to benefit from this combination therapy is needed.

Purpose: A multicenter phase II trial of ranpirnase (Onconase; Alfacell Corp, Bloomfield, NJ) as a single agent was conducted to further assess the safety and clinical efficacy of this novel antitumor ribonuclease. Patients with unresectable and histologically confirmed malignant mesothelioma (MM) were eligible., Patients and Methods: One hundred five patients with Eastern Cooperative Oncology Group performance status 0 to 2 were enrolled onto the study. Thirty-seven percent of patients had not responded to prior chemotherapy. The primary end point of the study was survival. Tumor responses and time to progression were also assessed. The Cancer and Leukemia Group B (CALGB) prognostic group criteria were used to define a treatment target group (TTG). Both the intent-to-treat (ITT) and the TTG populations were analyzed for survival., Results: Median survival times of 6 months for the ITT and 8.3 months for the TTG populations were observed. The 1- and 2-year survival rates were 34.3% and 21.6% for ITT, respectively, and 42% and 26.8% for TTG, respectively. Among the 81 patients assessable for tumor response, four had partial responses, two had minor regressions, and thirty-five experienced stabilization of previously progressive disease. Patients with responses and stable disease demonstrated markedly prolonged survival. Ranpirnase was well tolerated in the majority of patients, and there were no drug-related deaths., Conclusion: Ranpirnase demonstrated activity and a tolerable toxicity profile in patients with unresectable MM. The prognostic value of the CALGB groups was confirmed.

Background: Onconase, a protein isolated from oocytes and early embryos of the frog Rana pipiens, shares extensive homology with bovine pancreatic ribonuclease (RNase A) and possesses similar enzyme activity. Onconase is cytotoxic toward cancer cells in vitro and exhibits antitumor activity in animal models. In addition, Onconase has been shown to enhance the cytotoxic activity of some chemotherapeutic agents in vitro., Purpose: We studied interactions between the cytotoxic effects of Onconase and the chemotherapeutic agent vincristine (VCR) in the treatment of drug-sensitive and multidrug-resistant human colon carcinoma cells in vitro and in mice., Methods: Transplantable human colon carcinoma cells (HT-29par cells) were infected with a retrovirus containing human mdr1 (also known as MDR1 and PGY1) complementary DNA (encoding P-glycoprotein [P-gp]), and clones that were cross-resistant to colchicine, doxorubicin, and vinblastine were selected (HT-29mdr1 cells). Drug-resistant HT-29mdr1 cells and drug-sensitive HT-29par parental cells were treated with Onconase and/or VCR in vitro at varying concentrations to measure the effects on protein synthesis and cell viability. The impact of Onconase on VCR accumulation in both types of cells was determined in the presence or absence of MRK-16, an anti-P-gp monoclonal antibody capable of reversing the multidrug-resistant phenotype. The antitumor effects of Onconase and/or VCR treatment were assessed in nude mice bearing established HT-29par or HT-29mdr1 intraperitoneal tumors. IC50 values (drug concentrations resulting in 50% inhibition of protein synthesis or cell viability) for Onconase and VCR were determined from semilogarithmic dose-response curves; interactions between the cytotoxic effects of these two agents were evaluated using data from protein synthesis inhibition experiments and a two-way analysis of variance. Survival distributions from in vivo experiments were compared using Cox proportional hazards models., Results: The combination of Onconase and VCR yielded enhanced cytotoxicity in vitro that was independent of P-gp expression. Evaluation of the effects of these two compounds on protein synthesis over a wide range of drug concentrations indicated possible synergistic interactions (i.e., greater than additive effects) in both drug-resistant and drug-sensitive cells. The enhancement of VCR cytotoxicity was dependent on Onconase enzyme activity and was not associated with increased intracellular levels of VCR. Simultaneous treatment of mice bearing HT-29par tumors with Onconase and VCR did not extend their median survival time (MST) significantly (MST with VCR = 66 days; MST with VCR plus Onconase = 69 days; two-tailed P = .57); however, the MST of mice with HT-29mdr1 tumors was extended significantly by this treatment (MST with VCR = 44 days; MST with VCR plus Onconase = 66 days; two-tailed P<.001)., Conclusion: Combined administration of Onconase and VCR yields enhanced cytotoxicity in vitro and in vivo against human colon carcinoma cells that overexpress the mdr1 gene.