An anti-HER2 antibody drug conjugate with a novel topoisomerase I inhibitor, DS-8201a, was generated as a new anti-tumor drug candidate, and its preclinical pharmacological profile was assessed.
In vitro and in vivo pharmacological activities of DS-8201a were evaluated and compared with T-DM1 in several HER2-positive cell lines and patient-derived xenograft (PDX) models. The mechanism of action for the efficacy was also evaluated. Pharmacokinetics in cynomolgus monkeys and the safety profiles in rats and cynomolgus monkeys were assessed.
DS-8201a exhibited a HER2 expression-dependent cell growth inhibitory activity and induced tumor regression with a single dosing at more than 1 mg/kg in a HER2-positive gastric cancer NCI-N87 model. Binding activity to HER2 and ADCC activity of DS-8201a were comparable to unconjugated anti-HER2 antibody. DS-8201a also showed an inhibitory activity to Akt phosphorylation. DS-8201a induced phosphorylation of Chk1 and Histone H2A.X, the markers of DNA damage. Pharmacokinetics and safety profiles of DS-8201a were favorable and the highest non-severely toxic dose was 30 mg/kg in cynomolgus monkeys, supporting DS-8201a’s being well tolerated in humans. DS-8201a was effective in a T-DM1-insensitive PDX model with high HER2 expression. DS-8201a, but not T-DM1, demonstrated anti-tumor efficacy against several breast cancer PDX models with low HER2 expression.
DS-8201a exhibited a potent anti-tumor activity in a broad selection of HER2-positive models and favorable pharmacokinetics and safety profiles. The results demonstrate that DS-8201a will be a valuable therapy with a great potential to respond to T-DM1 insensitive HER2 positive cancers and low HER2-expressing cancers.
Copyright ©2016, American Association for Cancer Research (AACR) (Free AACR Whitepaper).

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Trabectedin (Yondelis, ecteinascidin-743, ET-743) is a marine-derived natural product approved for treatment of advanced soft tissue sarcoma and relapsed platinum-sensitive ovarian cancer. Lurbinectedin is a novel anticancer agent structurally related to trabectedin. Both ecteinascidins generate DNA double-strand breaks that are processed through homologous recombination repair (HRR), thereby rendering HRR-deficient cells particularly sensitive. We here characterize the DNA damage response (DDR) to trabectedin and lurbinectedin in HeLa cells. Our results show that both compounds activate the ATM/Chk2 (ataxia-telangiectasia mutated/checkpoint kinase 2) and ATR/Chk1 (ATM and RAD3-related/checkpoint kinase 1) pathways. Interestingly, pharmacological inhibition of Chk1/2, ATR or ATM is not accompanied by any significant improvement of the cytotoxic activity of the ecteinascidins while dual inhibition of ATM and ATR strongly potentiates it. Accordingly, concomitant inhibition of both ATR and ATM is an absolute requirement to efficiently block the formation of γ-H2AX, MDC1, BRCA1 and Rad51 foci following exposure to the ecteinascidins. These results are not restricted to HeLa cells, but are shared by cisplatin-sensitive and -resistant ovarian carcinoma cells. Together, our data identify ATR and ATM as central coordinators of the DDR to ecteinascidins and provide a mechanistic rationale for combining these compounds with ATR and ATM inhibitors.

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The efficacy of the smoking-cessation agent varenicline has been reported in Asian smokers; however, few studies have investigated factors that contribute to lapse and relapse.
This post hoc analysis aimed to identify predictors of smoking lapse and relapse.
This was a post-hoc analysis based on a double-blind, placebo-controlled, randomized, parallel-group study in which Japanese smokers (aged 20-75 years) who smoked ≥ 10 cigarettes/day and were motivated to quit were randomized to receive varenicline (0.25 mg twice daily [BID], 0.5 mg BID, 1 mg BID) or placebo for 12 weeks followed by a 40-week non-treatment follow-up. For inclusion in this analysis, participants must have been nicotine dependent (Tobacco Dependence Screener score ≥ 5) and must have successfully quit smoking continuously for 4 weeks (weeks 9-12). Lapse was defined by answering yes to ≥ 1 question in the Nicotine Use Inventory. Relapse was defined by participants having smoked for ≥ 7 days during follow-up measured by the Nicotine Use Inventory.
Of the 619 randomized individuals, 515 had a Tobacco Dependence Screener score of ≥ 5, and 277 quit smoking continuously from weeks 9 to 12. Approximately 75% were male, with a mean (SD) BMI of 23.0 (3.0) kg/m(2). Maximum length of continuous abstinence (CA) during treatment and age (both P < 0.0001) were significant predictors of lapse. Maximum CA (P < 0.0001), age (P = 0.0002), Minnesota Nicotine Withdrawal Scale (MNWS) score for urge to smoke (P = 0.0019), and having made ≥ 1 serious quit attempt (P = 0.0063) were significant predictors of relapse. For participants with a maximum CA of 4 to 6 weeks versus those with a maximum CA of 10 to 11 weeks, the ORs for lapse and relapse were 4.649 (95% CI, 2.071-10.434) and 3.337 (95% CI, 1.538-7.239), respectively. In participants aged 21-34 years versus those aged 47-72 years, the ORs for lapse and relapse were 3.453 (95% CI 1.851, 6.441) and 3.442 (95% CI 1.795, 6.597), respectively. Participants with a MNWS urge to smoke score of 2 to 4 versus 0 had an OR for relapse of 3.175 (95% CI, 1.166-8.644). Participants having made ≥ 1 versus no serious quit attempts had an OR for relapse of 2.108 (95% CI, 1.168-3.805).
Shorter maximum CA and younger age at quit attempt were associated with increased risk of lapse and relapse. Higher MNWS urge to smoke score and having made ≥ 1 serious quit attempt were associated with increased relapse risk. ClinicalTrials.gov identifier: NCT00139750.
Copyright © 2014 The Authors. Published by EM Inc USA.. All rights reserved.

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Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase responsible for the development of different tumor types. Despite the remarkable clinical activity of crizotinib (Xalkori), the first ALK inhibitor approved in 2011, the emergence of resistance mutations and of brain metastases frequently causes relapse in patients. Within our ALK drug discovery program, we identified compound 1, a novel 3-aminoindazole active on ALK in biochemical and in cellular assays. Its optimization led to compound 2 (entrectinib), a potent orally available ALK inhibitor active on ALK-dependent cell lines, efficiently penetrant the blood-brain barrier (BBB) in different animal species and highly efficacious in in vivo xenograft models. Moreover, entrectinib resulted to be strictly potent on the closely related tyrosine kinases ROS1 and TRKs recently found constitutively activated in several tumor types. Entrectinib is currently undergoing phase I/II clinical trial for the treatment of patients affected by ALK-, ROS1-, and TRK-positive tumors.

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Exosomes are small (30- to 100-nm) vesicles secreted by all cell types in culture and found in most body fluids. A mean of 1 mL of blood serum, derived from healthy donors, contains approximately 10(12) exosomes. Depending on the disease, the number of exosomes can fluctuate. Concentration of exosomes in the bloodstream and all other body fluids is extremely high. Several B-cell surface antigens (CD19, CD20, CD22, CD23, CD24, CD37, CD40, and HLA-DR) and the common leukocyte antigen CD45 are interesting in terms of immunotherapy of hematologic malignant neoplasms. The established standard for exosome isolation is ultracentrifugation. However, this method cannot discriminate between exosome subpopulations and other nanovesicles. The main purpose of this study was to characterize CD81(+) and CD63(+) subpopulations of exosomes in terms of these surface markers after release from various types of B-cell lymphoma cell lines using an easy and reliable method of immunomagnetic separation.
Western blotting, flow cytometry, and electron microscopy were used to compare the total preenriched extracellular vesicle (EV) pool to each fraction of vesicles after specific isolation, using magnetic beads conjugated with antibodies raised against the exosome markers CD63 and CD81.
Magnetic bead-based isolation is a convenient method to study and compare subpopulations of exosomes released from B-cell lymphoma cells. The data indicated that the specifically isolated vesicles differed from the total preenriched EV pool. CD19, CD20, CD24, CD37, and HLA-DR, but not CD22, CD23, CD40, and CD45, are expressed on exosomes from B-cell lymphoma cell lines with large heterogeneity among the different B-cell lymphoma cell lines. Interestingly, these B-cell lymphoma-derived EVs are able to rescue lymphoma cells from rituximab-induced complement-dependent cytotoxicity.
Distribution of exosomes that contain CD19, CD20, CD24, CD37, and HLA-DR may intercept immunotherapy directed against these antigens, which is important to be aware of for optimal treatment. The use of an immunomagnetic separation platform enables easy isolation and characterization of exosome subpopulations for further studies of the exosome biology to understand the potential for therapeutic and diagnostic use.
Copyright © 2014 The Authors. Published by EM Inc USA.. All rights reserved.

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