CHK1 Inhibition Synergizes with Gemcitabine Initially by Destabilizing the DNA Replication Apparatus

Combining cell-cycle checkpoint kinase inhibitors with the DNA-damaging chemotherapeutic agent gemcitabine offers clinical appeal, with a mechanistic rationale based chiefly on abrogation of gemcitabine-induced G2-M checkpoint activation. However, evidence supporting this mechanistic rationale from chemosensitization studies has not been consistent. Here we report a systematic definition of how pancreatic cancer cells harboring mutant p53 respond to this combination therapy, by combining mathematical models with large-scale quantitative biologic analyses of single cells and cell populations. Notably, we uncovered a dynamic range of mechanistic effects at different ratios of gemcitabine and CHK1 inhibitors. Remarkably, effective synergy was attained even where cells exhibited an apparently functional G2-M surveillance mechanism, as exemplified by a lack of both overt premature CDK1 activation and S-phase mitotic entry. Consistent with these findings, S-G2 duration was extended in treated cells, leading to a definable set of lineage-dependent catastrophic fates. At synergistic drug concentrations, global replication stress was a distinct indicator of chemosensitization as characterized molecularly by an accumulation of S-phase cells with high levels of hyperphosphorylated RPA-loaded single-stranded DNA. In a fraction of these cells, persistent genomic damage was observed, including chromosomal fragmentation with a loss of centromeric regions that prevented proper kinetochore-microtubule attachment. Together, our results suggested a "foot-in-the-door" mechanism for drug synergy where cells were destroyed not by frank G2-M phase abrogation but rather by initiating a cumulative genotoxicity that deregulated DNA synthesis.

HER2-Mutated Breast Cancer Responds to Treatment With Single-Agent Neratinib, a Second-Generation HER2/EGFR Tyrosine Kinase Inhibitor

Activating mutations in the HER2 tyrosine kinase have been identified in human breast cancers that lack HER2 gene amplification. These patients are not candidates for HER2-targeted drugs under current standards of care, but preclinical data strongly suggest that these patients will benefit from anti-HER2 drugs. This case report describes a young woman with metastatic breast cancer whose tumor was found to carry a HER2 L755S mutation, which is in the kinase domain of HER2. Treatment with the second-generation HER2/EGFR tyrosine kinase inhibitor neratinib resulted in partial response and dramatic improvement in the patient's functional status. This partial response lasted 11 months, and when the patient's cancer progressed, she was treated with neratinib plus capecitabine and her cancer again responded. This second response parallels the benefit seen with continuing trastuzumab in HER2-amplified breast cancer after disease progression. This case represents the first report, to our knowledge, of successful single-agent treatment of HER2-mutated breast cancer. Two clinical trials of neratinib for HER2-mutated metastatic breast cancer are currently enrolling patients. Further, data from The Cancer Genome Atlas project have identified HER2 mutations in a wide range of solid tumors, including bladder, colorectal, and non-small cell lung cancers, suggesting that clinical trials of neratinib or neratinib-based combinations for HER2-mutated solid tumors is warranted.

[Three Patients with Acute Myocardial Infarction Associated with Targeted Therapy of Sorafenib for Metastatic Renal Cell Carcinoma : Case Report]

Sorafenib is a tyrosine kinase inhibitor (TKI) of the vascular endothelial growth factor receptor (VEGFR) used for advanced renal cell carcinoma. Treatment with sorafenib prolongs progression-free survival in patients with advanced clear-cell renal cell carcinoma. However, in spite of its therapeutic efficacy, sorafenib causes a wide range of adverse events. Cardiovascular adverse events have been observed when sorafenib was used with targeted agents. Although these adverse events like hypertension, reduced left ventricular ejection fraction, cardiac ischemia or infarction were manageable with standard medical therapies in most cases, some had a poor clinical outcome. We report three cases of acute myocardial infarction associated with sorafenib in patients with metastatic renal cell carcinoma.

Dovitinib and erlotinib in patients with metastatic non-small cell lung cancer: A drug-drug interaction

INTRODUCTION

Erlotinib is a FDA approved small molecule inhibitor of epidermal growth factor receptor and dovitinib is a novel small molecule inhibitor of fibroblast growth factor and vascular endothelial growth factor receptor. This phase 1 trial was conducted to characterize the safety and determine the maximum tolerated dose of erlotinib plus dovitinib in patients with previously treated metastatic non-small cell lung cancer.

METHODS

Escalating dose cohorts of daily erlotinib and dovitinib dosed 5 days on/2 days off, starting after a 2-week lead-in of erlotinib alone, were planned. A potential pharmacokinetic interaction was hypothesized as dovitinib induces CYP1A1/1A2. Only cohort 1 (150 mg erlotinib+300 mg dovitinib) and cohort -1 (150 mg erlotinib+200mg dovitinib) enrolled. Plasma concentrations of erlotinib were measured pre- and post-dovitinib exposure.

RESULTS

Two of three patients in cohort 1 had a DLT (grade 3 transaminitis and grade 3 syncope). Two of 6 patients in cohort -1 had a DLT (grade 3 pulmonary embolism and grade 3 fatigue); thus, the study was terminated. Erlotinib exposure (average Cmax 2308±698 ng/ml and AUC 0-24 41,030±15,577 ng×h/ml) approximated previous reports in the six patients with pharmacokinetic analysis. However, erlotinib Cmax and AUC0-24 decreased significantly by 93% (p=0.02) and 97% (p<0.01), respectively, during dovitinib co-administration.

CONCLUSIONS

This small study demonstrated considerable toxicity and a significant pharmacokinetic interaction with a marked decrease in erlotinib exposure in the presence of dovitinib, likely mediated through CYP1A1/1A2 induction. Given the toxicity and the pharmacokinetic interaction, further investigation with this drug combination will not be pursued.

First-in-Man Dose-Escalation Study of the Selective BRAF Inhibitor RG7256 in Patients with BRAF V600-Mutated Advanced Solid Tumors

BACKGROUND

BRAF mutations are a validated target for cancer therapy. A second-generation BRAF inhibitor with an improved preclinical safety profile (RG7256) was evaluated in a first-in-man study in order to determine the safety, efficacy, pharmacokinetics and pharmacodynamics in patients with BRAF V600-mutated advanced solid tumors.

PATIENTS AND METHODS

Patients received RG7256 orally over 8 dose levels from 200 mg once a day (QD) to 2400 mg twice a day (BID) (50-, 100- and 150-mg tablets) using a classic 3 + 3 dose escalation design.

RESULTS

In total, 45 patients were enrolled; most (87 %) had advanced melanoma (94 % BRAF V600E). RG7256 was rapidly absorbed, with limited accumulation and dose-proportional increase in exposure up to 1950 mg BID. The maximal tolerated dose (MTD) was not reached. The most common drug-related adverse events (AEs) were dyspepsia (20 %), dry skin (18 %), rash (18 %), fatigue (16 %) and nausea (13 %), mainly grade 1. Three patients (7 %) developed cutaneous squamous cell carcinoma. Photosensitivity, arthralgia and increased liver enzyme levels were each observed in only one patient each. Of 44 evaluable patients, 14 (32 %) had a partial response (melanoma and thyroid cancer). At high dose levels (>1200 mg BID), 10 of 16 (63 %) patients had a partial response. A decrease in maximum standardized uptake value (SUVmax) on FDG-PET of ≥25 % was observed in 19 of 37 patients. On-treatment reductions in pERK were documented in eight of ten paired tumor samples.

CONCLUSIONS

RG7256 has a favorable safety profile compared to other BRAF inhibitors while maintaining clinical activity, and MTD was not reached. The excessive pill burden needed to provide the desired exposure, and thus concerns about patient compliance, limited further development of this agent. Study Identifier: ClinicalTrials.gov (NCT01143753).

Baseline and Trend of Lymphocyte-to-Monocyte Ratio as Prognostic Factors in Epidermal Growth Factor Receptor Mutant Non-Small Cell Lung Cancer Patients Treated with First-Line Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

Background

Patients with early-stage lung cancer who have a high baseline lymphocyte-to-monocyte ratio (LMR) have a favorable prognosis. However, the prognostic significance of LMR in patients with advanced-stage EGFR-mutant non-small cell lung cancer (NSCLC) receiving first-line epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) has not been established. We conducted a retrospective analysis to investigate the influence of LMR on clinical outcomes including progression-free survival (PFS) and overall survival (OS) in EGFR-mutant patients with NSCLC.

Materials and Methods

Of 1310 lung cancer patients diagnosed between January 2011 and October 2013, 253 patients receiving first-line EGFR-TKIs for EGFR-mutant NSCLC were included. The cut-off values for baseline and the 1-month-to-baseline ratio of LMR (MBR), determined by using receiver operating characteristic curves, were 3.29 and 0.63, respectively. Patients were divided into 3 prognostic groups: high LMR and MBR, high LMR or MBR, and low LMR and MBR.

Results

The mean patient age was 65.2 years, and 41% were men. The median PFS and OS were 10.3 and 22.0 months, respectively. The PFS in patients with high LMR and MBR, high LMR or MBR, and low LMR and MBR were 15.4, 7.1, and 2.0 months, respectively (p < 0.001), whereas the OS were 32.6, 13.7, and 5.1 months, respectively (p < 0.001).

Conclusion

A combination of baseline and trend of LMR can be used to identify patients with a high mortality risk in EGFR-mutant NSCLC patients receiving first-line EGFR-TKIs.

Randomized Phase II Trial of Erlotinib Beyond Progression in Advanced Erlotinib-Responsive Non-Small Cell Lung Cancer

BACKGROUND

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapy is clearly beneficial in patients with advanced EGFR-mutated non-small cell lung cancer (NSCLC). However, acquired resistance develops uniformly and the benefit of continuation of EGFR TKI therapy beyond progression remains unclear.

MATERIALS AND METHODS

This was a randomized phase II study of chemotherapy (arm A: pemetrexed or docetaxel) versus chemotherapy plus erlotinib (ERL) (arm B) in patients with progressive NSCLC following clinical benefit from erlotinib. In arm B, chemotherapy was given with erlotinib at an oral daily dose of 150 mg on days 2-19 of each cycle to minimize negative pharmacodynamic interactions. The primary endpoint was that continuation of erlotinib in this patient population could extend progression-free survival (PFS) by 50%.

RESULTS

A total of 46 patients were randomized (arm A: 24; arm B: 22). Patient characteristics were well balanced except there were more female patients in arm A (p = .075). The median PFS of patients in arm A was 5.5 months and for those in arm B, 4.4 months (p = .699). The response rates were 13% and 16% in arms A and B, respectively (p = .79). EGFR status data were available for 39 of the 46 patients and no significant difference in PFS was seen for continuing ERL beyond progression in mutation-positive patients. Substantially more toxicity was seen in arm B than arm A.

CONCLUSION

There was added toxicity but no benefit with the continuation of ERL beyond progression along with chemotherapy as compared with chemotherapy alone.

IMPLICATIONS FOR PRACTICE

The benefits of continuing erlotinib upon progression alongside conventional chemotherapy are unclear. This randomized phase II study, initiated prior to the establishment of routine epidermal growth factor receptor (EGFR) mutation testing, addressed this clinically relevant issue through randomizing patients with prior clinical benefit from erlotinib (thereby enriching for EGFR-mutated tumors) upon progression in the second- or third-line setting to conventional chemotherapy (single-agent pemetrexed or docetaxel) with or without continued erlotinib. The results showed no benefit to continuing erlotinib beyond progression, while significantly more side effects were noted in the combination arm. Along with other recently presented study findings, these results argue against the routine practice of continuing erlotinib in this setting.

Mechanism of Resistance and Novel Targets Mediating Resistance to EGFR and c-Met Tyrosine Kinase Inhibitors in Non-Small Cell Lung Cancer

Tyrosine kinase inhibitors (TKIs) against EGFR and c-Met are initially effective when administered individually or in combination to non-small cell lung cancer (NSCLC) patients. However, the overall efficacies of TKIs are limited due to the development of drug resistance. Therefore, it is important to elucidate mechanisms of EGFR and c-Met TKI resistance in order to develop more effective therapies. Model NSCLC cell lines H1975 and H2170 were used to study the similarities and differences in mechanisms of EGFR/c-Met TKI resistance. H1975 cells are positive for the T790M EGFR mutation, which confers resistance to current EGFR TKI therapies, while H2170 cells are EGFR wild-type. Previously, H2170 cells were made resistant to the EGFR TKI erlotinib and the c-Met TKI SU11274 by exposure to progressively increasing concentrations of TKIs. In H2170 and H1975 TKI-resistant cells, key Wnt and mTOR proteins were found to be differentially modulated. Wnt signaling transducer, active β-catenin was upregulated in TKI-resistant H2170 cells when compared to parental cells. GATA-6, a transcriptional activator of Wnt, was also found to be upregulated in resistant H2170 cells. In H2170 erlotinib resistant cells, upregulation of inactive GSK3β (p-GSK3β) was observed, indicating activation of Wnt and mTOR pathways which are otherwise inhibited by its active form. However, in H1975 cells, Wnt modulators such as active β-catenin, GATA-6 and p-GSK3β were downregulated. Additional results from MTT cell viability assays demonstrated that H1975 cell proliferation was not significantly decreased after Wnt inhibition by XAV939, but combination treatment with everolimus (mTOR inhibitor) and erlotinib resulted in synergistic cell growth inhibition. Thus, in H2170 cells and H1975 cells, simultaneous inhibition of key Wnt or mTOR pathway proteins in addition to EGFR and c-Met may be a promising strategy for overcoming EGFR and c-Met TKI resistance in NSCLC patients.

Clinical development of galunisertib (LY2157299 monohydrate), a small molecule inhibitor of transforming growth factor-beta signaling pathway

Transforming growth factor-beta (TGF-β) signaling regulates a wide range of biological processes. TGF-β plays an important role in tumorigenesis and contributes to the hallmarks of cancer, including tumor proliferation, invasion and metastasis, inflammation, angiogenesis, and escape of immune surveillance. There are several pharmacological approaches to block TGF-β signaling, such as monoclonal antibodies, vaccines, antisense oligonucleotides, and small molecule inhibitors. Galunisertib (LY2157299 monohydrate) is an oral small molecule inhibitor of the TGF-β receptor I kinase that specifically downregulates the phosphorylation of SMAD2, abrogating activation of the canonical pathway. Furthermore, galunisertib has antitumor activity in tumor-bearing animal models such as breast, colon, lung cancers, and hepatocellular carcinoma. Continuous long-term exposure to galunisertib caused cardiac toxicities in animals requiring adoption of a pharmacokinetic/pharmacodynamic-based dosing strategy to allow further development. The use of such a pharmacokinetic/pharmacodynamic model defined a therapeutic window with an appropriate safety profile that enabled the clinical investigation of galunisertib. These efforts resulted in an intermittent dosing regimen (14 days on/14 days off, on a 28-day cycle) of galunisertib for all ongoing trials. Galunisertib is being investigated either as monotherapy or in combination with standard antitumor regimens (including nivolumab) in patients with cancer with high unmet medical needs such as glioblastoma, pancreatic cancer, and hepatocellular carcinoma. The present review summarizes the past and current experiences with different pharmacological treatments that enabled galunisertib to be investigated in patients.

Effective delivery of a rationally designed intracellular peptide drug with gold nanoparticle-peptide hybrids

A novel gold nanoparticle-peptide hybrid strategy was developed to intracellularly deliver a potent PKCδ inhibitor peptide for the treatment of acute lung injury. The gold nanoparticle-peptide hybrids showed good stability with high uptake, and demonstrated in vitro and in vivo efficacy. Our formulation strategy shows great promise in intracellular delivery of peptides.

Cediranib or placebo in combination with cisplatin and gemcitabine chemotherapy for patients with advanced biliary tract cancer (ABC-03): a randomised phase 2 trial

BACKGROUND

Cisplatin and gemcitabine is the standard first-line chemotherapy regimen for patients with advanced biliary tract cancer; expression of VEGF and its receptors is associated with adverse outcomes. We aimed to assess the effect of the addition of cediranib (an oral inhibitor of VEGF receptor 1, 2, and 3) to cisplatin and gemcitabine on progression-free survival.

METHODS

In this multicentre, placebo-controlled, randomised phase 2 study, we recruited patients aged 18 years or older with histologically confirmed or cytologically confirmed advanced biliary tract cancer from hepatobiliary oncology referral centres in the UK. Patients were eligible if they had an ECOG performance status of 0-1 and an estimated life expectancy of longer than 3 months. Patients were given first-line cisplatin and gemcitabine chemotherapy (25 mg/m(2) cisplatin and 1000 mg/m(2) gemcitabine [on days 1 and 8 every 21 days, for up to eight cycles]) with either 20 mg oral cediranib or placebo once a day until disease progression. We randomly assigned patients (1:1) with a minimisation algorithm, incorporating the stratification factors: extent of disease, primary disease site, previous treatment, ECOG performance status, and centre. The primary endpoint was progression-free survival in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT00939848, and was closed on Sept 30, 2014; results of the final analysis for the primary endpoint are presented.

FINDINGS

Between April 5, 2011, and Sept 28, 2012, we enrolled 124 patients (62 in each group). With a median follow-up of 12·2 months (IQR 7·3-18·5), median progression-free survival was 8·0 months (95% CI 6·5-9·3) in the cediranib group and 7·4 months (5·7-8·5) in the placebo group (HR 0·93, 80% CI 0·74-1·19, 95% CI 0·65-1·35; p=0·72). Patients who received cediranib had more grade 3-4 toxic effects than did patients who received placebo: hypertension (23 [37%] vs 13 [21%]; p=0·05), diarrhoea (eight [13%] vs two [3%]; p=0·05); platelet count decreased (ten [16%] vs four [6%]; p=0·09), white blood cell decreased (15 [24%] vs seven [11%]; p=0·06) and fatigue (16 [24%] vs seven [11%]; p=0·04).

INTERPRETATION

Cediranib did not improve the progression-free survival of patients with advanced biliary tract cancer in combination with cisplatin and gemcitabine, which remains the standard of care. Although patients in the cediranib group had more adverse events, we recorded no unexpected toxic effects. The role of VEGF inhibition in addition to chemotherapy for patients with advanced biliary tract cancer remains investigational.

FUNDING

Cancer Research UK and AstraZeneca Pharmaceuticals.

Sorafenib treatment of radioiodine-refractory advanced thyroid cancer in daily clinical practice: a cohort study from a single center

Treatment options for recurrent or metastatic differentiated thyroid cancer (DTC) refractory to radioactive iodine (RAI) are inadequate. Multitargeted kinase inhibitors have recently shown promising results in phase 2-3 studies. This retrospective study aimed to document our clinical experience on the effects of sorafenib in the setting of daily clinical practice. Retrospective study evaluating the efficacy and safety of sorafenib in a cohort of patients consecutively treated with sorafenib at a single center. Twenty patients with advanced RAI-refractory thyroid carcinoma were enrolled (March 2011-March 2014). Patients generally started with 400 mg of sorafenib twice daily, tapering the dose in case of side effects. Radiological response and toxicity were measured during follow-up, together with safety parameters. CT scans were performed by a single experienced radiologist every 3-4 months. Five patients stopped sorafenib within 90 days due to severe toxicities. Median progression-free survival was 248 days. Five patients had a partial response (PR), achieved in all cases within 3 months, whereas 5 had stable disease (SD) at 12 months. Durable response rate (PR plus SD) for at least 6 months was 50 %, among those who received sorafenib for at least 3 months. Commonest adverse events included skin toxicity, gastrointestinal and constitutional symptoms. In our cohort of patients with advanced RAI-refractory thyroid carcinoma, sorafenib confirmed antitumor activity leading to SD or PR in the majority of cases, at the expense of clinically relevant side effects. More effective and tolerable agents are still needed in the treatment of RAI-refractory DTC.

Evaluation of sorafenib treatment and hepatic arterial infusion chemotherapy for advanced hepatocellular carcinoma: a comparative study using the propensity score matching method

While sorafenib (SFN) is the established worldwide standard therapeutic agent for advanced hepatocellular carcinoma (HCC), hepatic arterial infusion chemotherapy (HAIC) is also considered a favorable treatment for some advanced HCCs. This study aimed to evaluate each treatment and provide an optimal therapeutic choice for advanced HCCs. We analyzed 72 patients treated with SFN and 128 patients receiving HAIC. Both treatment groups were analyzed for prognostic and disease progression factors, and matched pair analysis was performed using the propensity score matching method. The preferable status of intrahepatic lesions, that is, no lesions or only a single (< 3 cm) intrahepetic lesion, was positively associated with good prognosis and negatively associated with disease progression in the SFN group. Maximum tumor size (> 5 cm) and low albumin (≤ 3.4 g/dL) were poor prognostic and disease progression factors in the HAIC group. Analysis of 53 patients selected from each of the SFN and HAIC groups based on the propensity score matching method showed no significant differences in survival or disease progression between the two matched subgroups. On the other hand, progression-free survival (PFS) in the HAIC-matched subgroup was significantly longer than in the SFN-matched subgroup, particularly in patients with portal vein invasion (PVI) and/or without extrahepatic spread (EHS). The treatment efficacy of HAIC is similar to that of SFN regarding survival and disease progression. Longer PFS might be expected for HAIC compared with SFN, particularly in patients with PVI and/or without EHS.

[Anti-angiogenesis and molecular targeted therapies]

Tumor angiogenesis contributes to the development of tumor progression. Several vascular endothelial growth factor(VEGF)-targeted agents, administered either as single agents or in combination with chemotherapy, have been shown to benefit patients with advanced-stage malignancies. In particular, bevacizumab is a humanized monoclonal antibody that specifically targets VEGF, inhibiting angiogenesis, thereby impeding tumor growth and survival. It is also possible that combined VEGF and the epidermal growth factor (EGFR) pathway blockade could further enhance antitumor efficacy and help prevent resistance to therapy. Preclinical and clinical studies have shown new various molecular targets and the functional characteristics of tumor angiogenesis, which may provide strategies for improving the therapeutic benefit.

[Pharmacokinetic issues on cancer pharmacotherapy]

Efficacy of cancer pharmacotherapy depends upon drug exposure to the body and responsiveness of the tumor to the drug treatment. Drug exposure is determined by pharmacokinetics and dose, whereas responsiveness is intrinsically variable by tumor heterogeneity. Molecular targeting drugs are used as promising therapy for cancers, and most of them are coupled with particular diagnostics which can predict responders and non-responders before treatment. On the other hand, lower drug exposure to the body can lead to insufficient efficacy. A number of important evidences have been published recently on exposure-response relationships for molecular targeting drugs including monoclonal antibodies and small molecules. In this chapter, two examples are presented; anti-HER2 antibody and tyrosine kinase inhibitor. Patients with the lowest trough concentrations of trastuzumab in cycle 1 showed shorter overall survival in metastatic gastric cancer study. Efficacy of imatinib in chronic myelogenous leukemia depended on plasma concentration of imatinib, and therapeutic drug monitoring (TDM) of imatinib is expected to improve the therapeutic outcome in CML.

Exploration of efficacy and bleeding with combined phosphoinositide 3-kinase β inhibition and aspirin in man

BACKGROUND

Based on animal and human data, phosphoinositide 3-kinase (PI3K)β is a promising antithrombotic target. However, the relation between efficacy and bleeding when combined with current antiplatelet therapies is unclear.

OBJECTIVE

To strengthen the PI3Kβ target validation using the short-acting inhibitor AZD6482 alone and in different combinations with P2Y12 and cyclooxygenase (COX)-1 inhibition in vitro (human platelets), in vivo (dog), and in healthy subjects.

METHODS AND RESULTS

Evaluation of complete target inhibition of PI3Kβ (by AZD6482), P2Y12 (by ticagrelor), and COX-1 (by aspirin) alone and in the different combinations vs. concentration responses for a panel of platelet agonists in vitro (adenosine diphosphate, collagen, thrombin receptor activating peptide) indicates that the rank order of antiplatelet efficacy is P2Y12  > PI3Kβ > COX-1 as monotherapy and P2Y12 plus PI3Kβ > P2Y12 plus COX-1 > PI3Kβ plus COX-1 as dual therapy, with little additional effect with triple therapy. Use of a conscious dog model to assess ex vivo antiplatelet effect in parallel with bleeding time prolongation (standard incision in the ear) confirms the wide separation of efficacy vs. bleeding for PI3Kβ inhibition and that this separation is reduced when combined with aspirin and more reduced when combined with clopidogrel. In healthy subjects, AZD6482, in combination with aspirin, shows a potential for greater antiplatelet potency but less bleeding potential compared with clopidogrel plus aspirin.

CONCLUSIONS

PI3Kβ inhibition, in comparison with P2Y12 and COX-1, delivers medium antiplatelet effect but with minimal bleeding. PI3Kβ inhibition, in combination with aspirin, in healthy subjects, provides a potential for greater overall antiplatelet effect compared with clopidogrel plus aspirin, but with significantly less bleeding potential.

VS-5584, a Novel PI3K-mTOR Dual Inhibitor, Inhibits Melanoma Cell Growth In Vitro and In Vivo

Melanomas cause over 76% of skin cancer deaths annually. Phosphatidylinositol 3-kinase (PI3K)-AKT-mammalian target of rapamycin (mTOR) signaling pathway is important for melanoma initiation and progression. In the current study, we evaluated the potential anti-melanoma effect of VS-5584, a novel and highly potent PI3K-mTOR dual inhibitor. We demonstrated that VS-5584 potently inhibited survival and proliferation of established (A375, A-2058 and SK-MEL-3 lines) and primary human melanoma cells, but was non-cytotoxic to non-cancerous human skin keratinocytes and B10BR murine melanocytes. At the meantime, VS-5584 induced caspase-dependent apoptotic death in melanoma cells, and its cytotoxicity was alleviated by the caspase inhibitors. At the molecular level, VS-5584 blocked AKT-mTOR activation and downregulated cyclin D1 expression in melanoma cells, while the expressions of Bcl-xL and Bcl-2 were not affected by VS-5584 treatment. On the other hand, a BH-3 mimetic Bcl-xL/Bcl-2 inhibitor ABT-737, as well as siRNA-mediated knockdown of Bcl-xL or Bcl-2, enhanced the activity of VS-5584 in melanoma cells. In vivo, oral administration of VS-5584 suppressed A375 melanoma xenograft growth in nude mice, and its activity was further enhanced by co-administration of ABT-737. These results provide the rationale for the clinical assessment of VS-5584 in melanoma patients and development of ABT-737 and other Bcl-xL/Bcl-2 inhibitors as the possible adjuvants.

CHZ868, a Type II JAK2 Inhibitor, Reverses Type I JAK Inhibitor Persistence and Demonstrates Efficacy in Myeloproliferative Neoplasms

Although clinically tested JAK inhibitors reduce splenomegaly and systemic symptoms, molecular responses are not observed in most myeloproliferative neoplasm (MPN) patients. We previously demonstrated that MPN cells become persistent to type I JAK inhibitors that bind the active conformation of JAK2. We investigated whether CHZ868, a type II JAK inhibitor, would demonstrate activity in JAK inhibitor persistent cells, murine MPN models, and MPN patient samples. JAK2 and MPL mutant cell lines were sensitive to CHZ868, including type I JAK inhibitor persistent cells. CHZ868 showed significant activity in murine MPN models and induced reductions in mutant allele burden not observed with type I JAK inhibitors. These data demonstrate that type II JAK inhibition is a viable therapeutic approach for MPN patients.

Targeting the Inactive Conformation of JAK2 in Hematological Malignancies

Activating JAK2 mutants cause hematological malignancies. Current clinical type I JAK2 inhibitors effectively relieve symptoms but fail to resolve the disease. In this issue of Cancer Cell, two articles by Wu and colleagues and Meyer and colleagues characterize a type II JAK2 inhibitor that is effective in preclinical models of JAK2-dependent myeloproliferative neoplasms and B cell acute lymphoblastic leukemia.

PF-06463922, an ALK/ROS1 Inhibitor, Overcomes Resistance to First and Second Generation ALK Inhibitors in Preclinical Models

We report the preclinical evaluation of PF-06463922, a potent and brain-penetrant ALK/ROS1 inhibitor. Compared with other clinically available ALK inhibitors, PF-06463922 displayed superior potency against all known clinically acquired ALK mutations, including the highly resistant G1202R mutant. Furthermore, PF-06463922 treatment led to regression of EML4-ALK-driven brain metastases, leading to prolonged mouse survival, in a superior manner. Finally, PF-06463922 demonstrated high selectivity and safety margins in a variety of preclinical studies. These results suggest that PF-06463922 will be highly effective for the treatment of patients with ALK-driven lung cancers, including those who relapsed on clinically available ALK inhibitors because of secondary ALK kinase domain mutations and/or brain metastases.

Activity of the Type II JAK2 Inhibitor CHZ868 in B Cell Acute Lymphoblastic Leukemia

A variety of cancers depend on JAK2 signaling, including the high-risk subset of B cell acute lymphoblastic leukemias (B-ALLs) with CRLF2 rearrangements. Type I JAK2 inhibitors induce paradoxical JAK2 hyperphosphorylation in these leukemias and have limited activity. To improve the efficacy of JAK2 inhibition in B-ALL, we developed the type II inhibitor CHZ868, which stabilizes JAK2 in an inactive conformation. CHZ868 potently suppressed the growth of CRLF2-rearranged human B-ALL cells, abrogated JAK2 signaling, and improved survival in mice with human or murine B-ALL. CHZ868 and dexamethasone synergistically induced apoptosis in JAK2-dependent B-ALLs and further improved in vivo survival compared to CHZ868 alone. These data support the testing of type II JAK2 inhibition in patients with JAK2-dependent leukemias and other disorders.

Chemotherapy plus Erlotinib versus Chemotherapy Alone for Treating Advanced Non-Small Cell Lung Cancer: A Meta-Analysis

BACKGROUND

Whether a combination of chemotherapy and erlotinib is beneficial for advanced non-small cell lung cancer (NSCLC) remains controversial. This study aimed to summarize the currently available evidence and compare the efficacy and safety of chemotherapy plus erlotinib versus chemotherapy alone for treating advanced NSCLC.

METHODS

EMBASE, PubMed, and the Cochrane Central Register of Controlled Trials were searched for relevant studies. Our protocol was registered in PROSPERO (CRD42014015015).

RESULTS

Nine randomized controlled trials with a total of 3599 patients were included. Compared to chemotherapy alone, chemotherapy plus erlotinib was superior in PFS (HR = 0.76 [95% CI 0.62, 0.92], P = 0.006), and no statistically significant difference was observed in OS (HR = 0.94 [95% CI 0.86, 1.03], P = 0.16). Intercalated erlotinib plus chemotherapy demonstrated improvements in PFS (HR = 0.67 [95% CI 0.50, 0.91], P = 0.009) and OS (HR = 0.82 [95% CI 0.69, 0.98], P = 0.03). Continuous erlotinib plus chemotherapy treatment failed to demonstrate improvements in PFS (HR = 0.91 [95% CI 0.80, 1.04], P = 0.16) and OS (HR = 0.98 [95% CI 0.89, 1.09], P = 0.75). The association of chemotherapy plus erlotinib with improvement in PFS was significant in never smoking patients (HR = 0.46 [95% CI 0.37, 0.56], P<0.00001) but not in smoking patients (HR = 0.70 [95% CI 0.49, 1.00], P = 0.05). Among patients with EGFR mutant tumors, chemotherapy plus erlotinib demonstrated significant improvements in PFS (HR = 0.31 [95% CI 0.17, 0.58], P = 0.0002) and OS (HR = 0.52 [95% CI 0.30, 0.88], P = 0.01). Among patients with EGFR wild-type tumors, no statistically significant difference was observed with respect to PFS (HR = 0.87 [95% CI 0.70, 1.08], P = 0.21) and OS (HR = 0.78 [95% CI 0.59, 1.01], P = 0.06).

CONCLUSION

Combination of chemotherapy and erlotinib is a viable treatment option for patients with NSCLC, especially for patients who never smoked and patients with EGFR mutation-positive disease. In addition, intercalated administration is an effective combinatorial strategy.

Midostaurin preferentially attenuates proliferation of triple-negative breast cancer cell lines through inhibition of Aurora kinase family

BACKGROUND

Breast cancer is classified into three subtypes by the expression of biomarker receptors such as hormone receptors and human epidermal growth factor receptor 2. Triple-negative breast cancer (TNBC) expresses none of these receptors and has an aggressive phenotype with a poor prognosis, which is insensitive to the drugs that target the hormone receptors and human epidermal growth factor receptor 2. It is, thus, required to develop an effective therapeutic reagent to treat TNBC.

RESULTS

The study using a panel of 19 breast cancer cell lines revealed that midostaurin, a multi-target protein kinase inhibitor, suppresses preferentially the growth of TNBC cells comparing with non-TNBC cells. Clustering analysis of the drug activity data for the panel of cancer cell lines predicted that midostaurin shares the target with Aurora kinase inhibitors. Following studies indicated that midostaurin attenuates the phosphorylation reaction mediated by Aurora kinase in the cells and directly inhibits this protein kinase in vitro, and that this reagent induces apoptosis accompanying accumulation of 4N and 8N DNA cells in TNBC cells.

CONCLUSION

Midostaurin suppresses the proliferation of TNBC cells among the breast cancer cell lines presumably through the inhibition of the Aurora kinase family. The precise study of midostaurin on cell growth will contribute to the development of the drug for the treatment of TNBC.

Phase 2 study of MK-2206, an allosteric inhibitor of AKT, as second-line therapy for advanced gastric and gastroesophageal junction cancer: A SWOG cooperative group trial (S1005)

BACKGROUND

The AKT inhibitor MK-2206 at a dose of 60 mg every other day was evaluated in gastric/gastroesophageal junction cancers.

METHODS

Patients who had progressed after first-line treatment were eligible. Pertinent eligibility criteria included adequate organ function, a fasting serum glucose level ≤ 150 mg/dL, and less than grade 2 malabsorption or chronic diarrhea. MK-2206 was given orally (60 evaluable patients required). The primary endpoint was overall survival, and a median survival of 6.5 months (power, 89%; significance level, 0.07) was considered encouraging for further investigation.

RESULTS

Seventy patients were included in the final analyses. The median age was 59.8 years (range, 30.4-86.7 years); 70% were male, 89% were white, and 7% were Asian. There were 2 deaths possibly related to the study drug (cardiac arrest and respiratory failure). Grade 4 adverse events included hyperglycemia, anemia, and lung infection (1 each). Grade 3 adverse events occurred in < 5% of patients except for fatigue (6%). Other adverse events (all grades) included anemia (17%), anorexia (30%), diarrhea (26%), fatigue (50%), hyperglycemia (30%), nausea (40%), vomiting (22%), dry skin (19%), maculopapular rash (30%), and acneiform rash (13%). The response rate was 1%, the median progression-free survival was 1.8 months (95% confidence interval, 1.7-1.8 months), and the median overall survival was 5.1 months (95% confidence interval, 3.7-9.4 months)

CONCLUSIONS

MK-2206 as second-line therapy was well tolerated by an unselected group of patients with gastric/gastroesophageal junction cancers, but it did not have sufficient activity (response rate, 1%; overall survival, 5.1 months) to warrant further testing in this population.