Phase I and pharmacokinetic study of UCN-01 in combination with irinotecan in patients with solid tumors

Synthesis and Antitumor Activity of Staurosporine Derivatives

Twenty-four derivatives of staurosporine were synthesized by modification at the 3′- N, 3- and 7-positions. Of these compounds, 16 were synthesized for the first time and their structures were determined by NMR spectroscopy, ECD, and HRESIMS. Their inhibitory activities against seven tumor cell lines, MV4-11 (leukemia), MCF-7 (breast carcinoma), HCT-116 (colon cancer), TE-1 (esophageal carcinoma), PATU8988 T (pancreatic cancer), HOS (osteosarcoma) and GBC-SD (gallbladder cancer), and human normal liver cell L-02 were evaluated using a Cell Counting Kit-8. The IC50 values for 7-oxo-3′- N-benzoylstaurosporin (4) on MV4-11 and PATU8988 T cells were 0.078 and 0.666 μmol/L, and the selection indexes were 1254 and 147, respectively. The IC50 values of 7-oxo-3-chloro-3′- N-benzoylstaurosporine (5) and (7 R)-7-hydroxy-3-bromo-3′- N-acetylstaurosporine (24) on MCF-7 cells were 0.029 and 0.021 μmol/L, and the selection indexes were 102 and 221, respectively. The above compounds have the potential to be developed further into antitumor drugs due to the advantages of high efficiency and low toxicity.

Activators and Inhibitors of Protein Kinase C (PKC): Their Applications in Clinical Trials

Protein kinase C (PKC), a family of phospholipid-dependent serine/threonine kinase, is classed into three subfamilies based on their structural and activation characteristics: conventional or classic PKC isozymes (cPKCs; α, βI, βII, and γ), novel or non-classic PKC isozymes (nPKCs; δ, ε, η, and θ), and atypical PKC isozymes (aPKCs; ζ, ι, and λ). PKC inhibitors and activators are used to understand PKC-mediated intracellular signaling pathways and for the diagnosis and treatment of various PKC-associated diseases, such as cancers, neurological diseases, cardiovascular diseases, and infections. Many clinical trials of PKC inhibitors in cancers showed no significant clinical benefits, meaning that there is a limitation to design a cancer therapeutic strategy targeting PKC alone. This review will focus on the activators and inhibitors of PKC and their applications in clinical trials.

Review of Chromatographic Bioanalytical Assays for the Quantitative Determination of Marine-Derived Drugs for Cancer Treatment

The discovery of marine-derived compounds for the treatment of cancer has seen a vast increase over the last few decades. Bioanalytical assays are pivotal for the quantification of drug levels in various matrices to construct pharmacokinetic profiles and to link drug concentrations to clinical outcomes. This review outlines the different analytical methods that have been described for marine-derived drugs in cancer treatment hitherto. It focuses on the major parts of the bioanalytical technology, including sample type, sample pre-treatment, separation, detection, and quantification.

UCN–SiO2–GO: a core shell and conjugate system for controlling delivery of doxorubicin by 980 nm NIR pulse

Herein, graphene oxide (GO) has been attached with core–shell upconversion-silica (UCN–SiO₂) nanoparticles (NPs) to form a GO–UCN–SiO₂ hybrid nanocomposite and used for controlled drug delivery. The formation of the nanocomposite has been confirmed by various characterization techniques. To date, a number of reports are available on GO and its drug delivery applications, however, the synergic properties that arise due to the combination of GO, UCNPs and SiO₂ can be used for controlled drug delivery. New composite UCN@SiO₂–GO has been synthesized through a bio-conjugation approach and used for drug delivery applications to counter the lack of quantum efficiency of the upconversion process and control sustained release. A model anticancer drug (doxorubicin, DOX) has been loaded to UCNPs, UCN@SiO₂ NPs and the UCN@SiO₂–GO nanocomposite. The photosensitive release of DOX from the UCN@SiO₂–GO nanocomposite has been studied with 980 nm NIR laser excitation and the results obtained for UCNPs and UCN@SiO₂ NPs compared. It is revealed that the increase in the NIR laser irradiation time from 1 s to 30 s leads to an increase in the amount of DOX release in a controlled manner. In vitro studies using model cancer cell lines have been performed to check the effectiveness of our materials for controlled drug delivery and therapeutic applications. Obtained results showed that the designed UCN@SiO₂–GO nanocomposite can be used for controlled delivery based therapeutic applications and for cancer treatment.

A GO–UCN–SiO₂ hybrid nanocomposite for loading of doxorubicin and its use in in vitro efficiency for killing carcinoma cells.

Protein Kinase Cζ Inhibitor Promotes Resolution of Bleomycin-Induced Acute Lung Injury

Protein kinase Cζ (PKCζ) is highly expressed in the lung, where it plays several regulating roles in the pathogenesis of acute lung injury (ALI). Proliferation and differentiation of integrin β4⁺ distal lung epithelial progenitor cells seem to play a key role in proper lung regeneration. We investigated the effects of a myristoylated PKCζ inhibitor (PKCζi) in a murine model of bleomycin-induced ALI. After intratracheal injury, we treated mice three times a week with PKCζi or its vehicle, DMSO. We found that mice injured with bleomycin and then treated with PKCζi for one week showed decreased activation of PKCζ, improved lung compliance, and decreased lung protein permeability compared to injured mice treated with DMSO. Mice treated continuously with PKCζi for 6 weeks showed reduced evidence of lung fibrosis by computed tomographic images, decreased lung collagen deposition, and decreased active transforming growth factor-β in the bronchoalveolar lavage fluid. In addition, we found an increased number of lung β4⁺ cells compared to DMSO at Week 6. Therefore, we grew isolated integrin β4⁺ lung progenitor cells in the presence of PKCζi or DMSO and found that β4⁺ cells treated with PKCζi proliferated more in vitro compared to DMSO. We conclude that the use of a PKCζi promotes resolution of lung fibrosis in a bleomycin ALI model and increases the number of β4⁺ progenitor cells with regenerative potential in the lung.

Phase 1 Study of ABT-751 in Combination With CAPIRI (Capecitabine and Irinotecan) and Bevacizumab in Patients With Advanced Colorectal Cancer

ABT-751 is an orally bioavailable sulfonamide with antimitotic properties. A nonrandomized phase 1 dose-escalation study of ABT-751 in combination with CAPIRI (capecitabine and irinotecan) and bevacizumab was conducted to define the maximum tolerated dose, dose-limiting toxicity (DLT), and pharmacokinetics in patients with advanced colorectal cancer. Patients were treated with ABT-751 daily for 7 days (alone) and then began 21-day cycles of treatment with ABT-751 daily and capecitabine twice daily for 14 days plus irinotecan on day 1 intravenously. Bevacizumab was added as standard of care at 7.5 mg/kg on day 1 after the first 2 dose levels. Because of intolerance to the regimen, a reduced dose of ABT-751 was also explored with reduced-dose and full-dose CAPIRI with bevacizumab. ABT-751 and irinotecan pharmacokinetics, ABT-751 glucuronidation, and protein binding were explored. Twenty-four patients were treated over 5 dose levels. The maximum tolerated dose was ABT-751 125 mg combined with full-dose CAPIRI and bevacizumab 7.5 mg/kg on day 1. DLTs were hypokalemia, elevated liver tests, and febrile neutropenia. ABT-751 is metabolized by UGT1A8 and to a lesser extent UGT1A4 and UGT1A1. Irinotecan and APC exposure were increased, SN-38 exposure was similar, and SN-38 glucuronide exposure was decreased. Clinically relevant alterations in ABT-751 and irinotecan pharmacokinetics were not observed. Despite modest efficacy, the combination of ABT-751, CAPIRI, and bevacizumab will not be studied further in colorectal cancer.

Trial Watch: Targeting ATM-CHK2 and ATR-CHK1 pathways for anticancer therapy

The ataxia telangiectasia mutated serine/threonine kinase (ATM)/checkpoint kinase 2 (CHEK2, best known as CHK2) and the ATM and Rad3-related serine/threonine kinase (ATR)/CHEK1 (best known as CHK1) cascades are the 2 major signaling pathways driving the DNA damage response (DDR), a network of processes crucial for the preservation of genomic stability that act as a barrier against tumorigenesis and tumor progression. Mutations and/or deletions of ATM and/or CHK2 are frequently found in tumors and predispose to cancer development. In contrast, the ATR-CHK1 pathway is often upregulated in neoplasms and is believed to promote tumor growth, although some evidence indicates that ATR and CHK1 may also behave as haploinsufficient oncosuppressors, at least in a specific genetic background. Inactivation of the ATM-CHK2 and ATR-CHK1 pathways efficiently sensitizes malignant cells to radiotherapy and chemotherapy. Moreover, ATR and CHK1 inhibitors selectively kill tumor cells that present high levels of replication stress, have a deficiency in p53 (or other DDR players), or upregulate the ATR-CHK1 module. Despite promising preclinical results, the clinical activity of ATM, ATR, CHK1, and CHK2 inhibitors, alone or in combination with other therapeutics, has not yet been fully demonstrated. In this Trial Watch, we give an overview of the roles of the ATM-CHK2 and ATR-CHK1 pathways in cancer initiation and progression, and summarize the results of clinical studies aimed at assessing the safety and therapeutic profile of regimens based on inhibitors of ATR and CHK1, the only 2 classes of compounds that have so far entered clinics.

Targeting head and neck cancer stem cells to overcome resistance to photon and carbon ion radiation

Although promising new radiation therapy techniques such as hadrontherapy are currently being evaluated in the treatment of head and neck malignancies, local control of head and neck squamous cell carcinoma (HNSCC) remains low. Here, we investigated the involvement of cancer stem-like cells (CSCs) in a radioresistant HNSCC cell line (SQ20B). Stem-like cells SQ20B/SidePopulation(SP)/CD44(+)/ALDH(high) were more resistant to both photon and carbon ion irradiation compared with non-CSCs. This was confirmed by a BrdU labeling experiment, which suggests that CSCs were able to proliferate and to induce tumorigenicity after irradiation. SQ20B/SP/CD44(+)/ALDH(high) were capable of an extended G2/M arrest phase in response to photon or carbon ion irradiation compared with non-CSCs. Moreover, our data strongly suggest that resistance of CSCs may result from an imbalance between exacerbated self-renewal and proliferative capacities and the decrease in apoptotic cell death triggering. In order to modulate these processes, two targeted pharmacological strategies were tested. Firstly, UCN-01, a checkpoint kinase (Chk1) inhibitor, induced the relapse of G2/M arrest and radiosensitization of SQ20B-CSCs. Secondly, all-trans retinoic acid (ATRA) resulted in an inhibition of ALDH activity, and induction of the differentiation and radiosensitization of SQ20B/SP/CD44(+)/ALDH(high) cells. The combination of ATRA and UCN-01 treatments with irradiation drastically decreased the surviving fraction at 2Gy of SQ20B-CSCs from 0.85 to 0.38 after photon irradiation, and from 0.45 to 0.21 in response to carbon ions. Taken together, our results suggest that the combination of UCN-01 and ATRA represent a promising pharmacological-targeted strategy that significantly sensitizes CSCs to photon or carbon ion radiation.

An unusual role for a mobile flavin in StaC-like indolocarbazole biosynthetic enzymes

The indolocarbazole biosynthetic enzymes StaC, InkE, RebC, and AtmC mediate the degree of oxidation of chromopyrrolic acid on route to the natural products staurosporine, K252a, rebeccamycin, and AT2433-A1, respectively. Here, we show that StaC and InkE, which mediate a net 4-electron oxidation, bind FAD with a micromolar K(d), whereas RebC and AtmC, which mediate a net 8-electron oxidation, bind FAD with a nanomolar K(d) while displaying the same FAD redox properties. We further create RebC-10x, a RebC protein with ten StaC-like amino acid substitutions outside of previously characterized FAD-binding motifs and the complementary StaC-10x. We find that these mutations mediate both FAD affinity and product specificity, with RebC-10x displaying higher StaC activity than StaC itself. X-ray structures of this StaC catalyst identify the substrate of StaC as 7-carboxy-K252c and suggest a unique mechanism for this FAD-dependent enzyme.

Proapoptotic chemotherapeutic drugs induce noncanonical processing and release of IL-1β via caspase-8 in dendritic cells

The identification of noncanonical (caspase-1-independent) pathways for IL-1β production has unveiled an intricate interplay between inflammatory and death-inducing signaling platforms. We found a heretofore unappreciated role for caspase-8 as a major pathway for IL-1β processing and release in murine bone marrow-derived dendritic cells (BMDC) costimulated with TLR4 agonists and proapoptotic chemotherapeutic agents such as doxorubicin (Dox) or staurosporine (STS). The ability of Dox to stimulate release of mature (17-kDa) IL-1β was nearly equivalent in wild-type (WT) BMDC, Casp1(-/-)Casp11(-/-) BMDC, WT BMDC treated with the caspase-1 inhibitor YVAD, and BMDC lacking the inflammasome regulators ASC, NLRP3, or NLRC4. Notably, Dox-induced production of mature IL-1β was temporally correlated with caspase-8 activation in WT cells and greatly suppressed in Casp8(-/-)Rip3(-/-) or Trif(-/-) BMDC, as well as in WT BMDC treated with the caspase-8 inhibitor, IETD. Similarly, STS stimulated robust IL-1β processing and release in Casp1(-/-)Casp11(-/-) BMDC that was IETD sensitive. These data suggest that TLR4 induces assembly of caspase-8-based signaling complexes that become licensed as IL-1β-converting enzymes in response to Dox and STS. The responses were temporally correlated with downregulation of cellular inhibitor of apoptosis protein 1, suggesting suppressive roles for this and likely other inhibitor of apoptosis proteins on the stability and/or proteolytic activity of the caspase-8 platforms. Thus, proapoptotic chemotherapeutic agents stimulate the caspase-8-mediated processing and release of IL-1β, implicating direct effects of such drugs on a noncanonical inflammatory cascade that may modulate immune responses in tumor microenvironments.

Kinesin spindle protein (KSP) inhibitors in combination with chemotherapeutic agents for cancer therapy

A diverse group of proteins, the activities of which are precisely orchestrated during mitosis, have emerged as targets for cancer therapeutics; these include the Aurora kinases (AKs), Polo-like kinases (PLKs), and the kinesin spindle protein (KSP). KSP is essential for the proper separation of spindle poles during mitosis. Agents that target KSP selectively act on cells undergoing cell division, which means that KSP inhibitors are mitosis-specific drugs, and have demonstrated remarkable activities in vitro. However, a significant obstacle to the success of KSP inhibitors is that these compounds, with tremendous efficacy in vitro, have demonstrated little or even no antitumor activity in vivo. Accumulated data suggest that a combination of KSP inhibitors with various cytostatic drugs will result in a more powerful tumor-killing effect than monotherapy. Combination therapies might predominate and represent the next frontier in the discovery research of KSP inhibitors as potential anticancer drugs. Few published studies have reviewed combination therapy using KSP inhibitors. Herein we provide a comprehensive review of the literature on KSP inhibitor monotherapy and therapeutic combinations. The current state and problems are also discussed.

UCN-01 induces S and G2/M cell cycle arrest through the p53/p21(waf1) or CHK2/CDC25C pathways and can suppress invasion in human hepatoma cell lines

BACKGROUND

UCN-01 (7-hydroxystaurosporine), a protein kinase inhibitor, has attracted a great deal of attention as a potent antitumour agent. Several clinical trials of UCN-01 alone or in combination with other agents for different tumour types are currently underway, and some of these trials have had positive results. Hepatocellular carcinoma has high incidence rates and is associated with poor prognosis and high mortality rates.

METHODS

Three different hepatoma cell lines (Huh7, HepG2, and Hep3B) were treated with different concentrations of UCN-01, and the anti-tumour effects of UCN-01 were evaluated. Following UCN-01 treatment, cell growth was measured using an MTT assay, cell cycle arrest was assayed using flow cytometry, and the mechanisms of cell cycle arrest and invasion inhibition were investigated through western blotting and a Matrigel invasion assay.

RESULTS

After a 72-h UCN-01 treatment, the growth of different hepatoma cell lines was significantly inhibited in a dose-dependent manner, with IC50 values ranging from 69.76 to 222.74 nM. Flow cytometry results suggested that UCN-01 inhibits proliferation in the hepatoma cells by inducing S and G2/M phase arrest, but not G1/S arrest, which differs from previous reports that used other tumour cell lines. Western blot results illustrated that UCN-01 induces a G2/M phase arrest, regardless of the status of the p53/P21(waf1) pathway, whereas the CHK2/CDC25C pathway and the p53/p21(waf1)pathway were involved in the UCN-01-induced S phase arrest. UCN-01 remarkably inhibited Huh7 cell invasion in a time-dependent manner. Suppression of Huh7 cell invasion may be due to the down-regulation of phosphorylated β-catenin by UCN-01.

CONCLUSIONS

These findings suggest that UCN-01 induces hepatoma cell growth inhibition by regulating the p53/p21(waf1) and CHK2/CDC25 pathways. Suppression of Huh7 cell invasion by UCN-01 may be due to the down-regulation of phosphorylated β-catenin. These data lend support for further studies on UCN-01 as a promising anti-HCC candidate.

Targeting triple negative breast cancer: is p53 the answer?

Triple negative breast cancers, which are defined by lack of expression of estrogen, progesterone, or HER2 receptors, represent approximately 15% of all breast cancers, although they account for a much higher proportional of breast cancer mortality. This is due both to their innate aggressive biological characteristics, but also to lack of effective therapies. Conventional chemotherapy is currently the only treatment option, thus there is a critical need to find new and effective targeted therapies in this disease. While investigation of agents such as poly (ADP-ribose) polymerase (PARP) inhibitors and EGFR inhibitors continues, results from recent clinical trials indicate that these therapies are not as active in sporadic triple negative breast cancers as initially hoped. It is important therefore to consider other emerging therapeutic agents. Mutation in p53 is found in the vast majority of triple negative breast cancers, and as such is a target of particular interest. Within this review, several agents with potential activity against aberrant p53 signaling have been considered, as a novel approach to finding an effective targeted therapy for this aggressive breast cancer subtype.

A phase II study of UCN-01 in combination with irinotecan in patients with metastatic triple negative breast cancer

Mutations in TP53 lead to a defective G1 checkpoint and the dependence on checkpoint kinase 1 (Chk1) for G2 or S phase arrest in response to DNA damage. In preclinical studies, Chk1 inhibition resulted in enhanced cytotoxicity of several chemotherapeutic agents. The high frequency of TP53 mutations in triple negative breast cancer (TNBC: negative for estrogen receptor, progesterone receptor, and HER2) make Chk1 an attractive therapeutic target. UCN-01, a non-selective Chk1 inhibitor, combined with irinotecan demonstrated activity in advanced TNBC in our Phase I study. The goal of this trial was to further evaluate this treatment in women with TNBC. Patients with metastatic TNBC previously treated with anthracyclines and taxanes received irinotecan (100–125 mg/m² IV days 1, 8, 15, 22) and UCN-01 (70 mg/m² IV day 2, 35 mg/m² day 23 and subsequent doses) every 42-day cycle. Peripheral blood mononuclear cells (PBMC) and tumor specimens were collected. Twenty five patients were enrolled. The overall response (complete response (CR) + partial response (PR)) rate was 4 %. The clinical benefit rate (CR + PR + stable disease ≥6 months) was 12 %. Since UCN-01 inhibits PDK1, phosphorylated ribosomal protein S6 (pS6) in PBMC was assessed. Although reduced 24 h post UCN-01, pS6 levels rose to baseline by day 8, indicating loss of UCN-01 bioavailability. Immunostains of γH2AX and pChk1^S296 on serial tumor biopsies from four patients demonstrated an induction of DNA damage and Chk1 activation following irinotecan. However, Chk1 inhibition by UCN-01 was not observed in all tumors. Most tumors were basal-like (69 %), and carried mutations in TP53 (53 %). Median overall survival in patients with TP53 mutant tumors was poor compared to wild type (5.5 vs. 20.3 months, p = 0.004). This regimen had limited activity in TNBC. Inconsistent Chk1 inhibition was likely due to the pharmacokinetics of UCN-01. TP53 mutations were associated with a poor prognosis in metastatic TNBC.

Phase I pharmacokinetic and pharmacodynamic study of cetuximab, irinotecan and sorafenib in advanced colorectal cancer

Background This phase Ib study was designed to determine the maximum tolerated doses (MTD) and dose limiting toxicities (DLTs) of irinotecan and cetuximab with sorafenib. Secondary objectives included characterizing the pharmacokinetics and pharmacodynamics and evaluating preliminary antitumor activity in patients with advanced colorectal cancer (CRC). Methods Patients with metastatic, pretreated CRC were treated at five dose levels. Results Eighteen patients were recruited with median age 56.5 years. In the first five patients treated, 2 irinotecan related DLTs were observed. With reduced dose intensity irinotecan, there were no further DLTs. The most common toxicities were diarrhea, nausea/vomiting, fatigue, anorexia and rash. DLTs included neutropenia and thrombocytopenia. Two patients had partial responses (one with a KRAS mutation) and 8 had stable disease (8-36 weeks). The median progression free survival (PFS) and overall survival (OS) were 2.5 and 4.7 months respectively. Pharmacokinetic analyses suggest sorafenib and metabolite exposure correlate with OS and DLTs. Conclusions The recommended phase II dose (RP2D) is irinotecan 100 mg/m(2) i.v. days 1, 8; cetuximab 400 mg/m(2) i.v. days 1 and 250 mg/m(2) i.v. weekly; and sorafenib 400 mg orally twice daily in advanced, pretreated CRC. The combination resulted in a modest response rate.

Chemotherapy-induced weakness and fatigue in skeletal muscle: the role of oxidative stress

SIGNIFICANCE

Fatigue is one of the most common symptoms of cancer and its treatment, manifested in the clinic through weakness and exercise intolerance. These side effects not only compromise patient's quality of life (QOL), but also diminish physical activity, resulting in limited treatment and increased morbidity.

RECENT ADVANCES

Oxidative stress, mediated by cancer or chemotherapeutic agents, is an underlying mechanism of the drug-induced toxicity. Nontargeted tissues, such as striated muscle, are severely affected by oxidative stress during chemotherapy, leading to toxicity and dysfunction.

CRITICAL ISSUES

These findings highlight the importance of investigating clinically applicable interventions to alleviate the debilitating side effects. This article discusses the clinically available chemotherapy drugs that cause fatigue and oxidative stress in cancer patients, with an in-depth focus on the anthracycline doxorubicin. Doxorubicin, an effective anticancer drug, is a primary example of how chemotherapeutic agents disrupt striated muscle function through oxidative stress.

FUTURE DIRECTIONS

Further research investigating antioxidants could provide relief for cancer patients from debilitating muscle weakness, leading to improved quality of life.

Identification of a conserved anti-apoptotic protein that modulates the mitochondrial apoptosis pathway

Here we identified an evolutionarily highly conserved and ubiquitously expressed protein (C9orf82) that shows structural similarities to the death effector domain of apoptosis-related proteins. RNAi knockdown of C9orf82 induced apoptosis in A-549 and MCF7/casp3-10b lung and breast carcinoma cells, respectively, but not in cells lacking caspase-3, caspase-10 or both. Apoptosis was associated with activated caspases-3, -8, -9 and -10, and inactivation of caspases 10 or 3 was sufficient to block apoptosis in this pathway. Apoptosis upon knockdown of C9orf82 was associated with increased caspase-10 expression and activation, which was required for the generation of an 11 kDa tBid fragment and activation of Caspase-9. These data suggest that C9orf82 functions as an anti-apoptotic protein that modulates a caspase-10 dependent mitochondrial caspase-3/9 feedback amplification loop. We designate this ubiquitously expressed and evolutionarily conserved anti-apoptotic protein Conserved Anti-Apoptotic Protein (CAAP). We also demonstrated that treatment of MCF7/casp3-10b cells with staurosporine and etoposides induced apoptosis and knockdown of CAAP expression. This implies that the CAAP protein could be a target for chemotherapeutic agents.

Phase I studies of CBP501, a G2 checkpoint abrogator, as monotherapy and in combination with cisplatin in patients with advanced solid tumors

PURPOSE

Two phase I dose-escalation studies were conducted to determine the maximum tolerated dose (MTD) and safety profile of the G(2) checkpoint abrogator CBP501, as a single agent and in combination with cisplatin.

EXPERIMENTAL DESIGN

Patients with advanced solid tumors were treated with CBP501 alone (D1/D8/D15, q4w, from 0.9 mg/m(2)), or with cisplatin (both on D1, q3w, from 3.6 mg/m(2) CBP501, 50 mg/m(2) cisplatin). Dose escalation proceeded if dose-limiting toxicity (DLT) was observed in 1 or less of 3 to 6 patients; CBP501 dose increments were implemented according to the incidence of toxicity. MTD was determined from DLTs occurring during the first two cycles.

RESULTS

In the combination study, the DLT was a histamine-release syndrome (HRS) occurring 10 to 60 minutes after initiating infusion that was attenuated by prophylaxis comprising dexamethasone, diphenhydramine, ranitidine, and loratadine. The MTD was 25 mg/m(2) CBP501 and 75 mg/m(2) cisplatin, with two patients at the highest dose (36.4 mg/m(2) CBP501, 75 mg/m(2) cisplatin) experiencing grade 3 HRS. The only DLT with monotherapy was transient G(3) rise of troponin in one patient. Grade 3 to 4 treatment-related events were rare. Promising activity was observed with CBP501/cisplatin, mainly in ovarian and mesothelioma patients who had previously progressed on platinum-containing regimens. Among ovarian cancer patients, low expression of DNA repair proteins was associated with partial response or stable disease.

CONCLUSIONS

CBP501 is well tolerated in patients as monotherapy and with cisplatin. At the recommended phase II dose (RP2D), the combination is feasible and HRS manageable with prophylaxis. Evidence of antitumor activity was observed in platinum-resistant patients.

Protein kinase C regulates ezrin-radixin-moesin phosphorylation in canine osteosarcoma cells

The development of metastasis is the most significant cause of death for both canine and human patients with osteosarcoma (OS). Ezrin has been associated with tumour progression and metastasis in human, canine and murine OS. Ezrin activation is dynamically regulated by protein kinase C (PKC) during metastatic progression in human and murine OS. To include the dog in the development of therapeutics that target ezrin biology, we characterized four new canine OS cell lines and confirmed the relationship between PKC and ezrin in these cells. Three of four cell lines formed tumours in mice that were histologically consistent with OS. All cell lines were markedly aneuploid and expressed ezrin and PKC. Finally, both ezrin phosphorylation and cell migration were inhibited using a PKC inhibitor. These data suggest that an association between PKC-mediated activation of ezrin and the metastatic phenotype in canine OS cells.

Death by releasing the breaks: CHK1 inhibitors as cancer therapeutics

Defects in p53 function, which occur frequently in human cancers due to mutations in TP53 or disruptions in the p53 regulatory pathway, render cells dependent on CHK1 (Checkpoint Kinase 1) to activate cell cycle checkpoints. In the presence of DNA damage or replication stress, inhibition of CHK1 leads to "mitotic catastrophe" and cell death in p53-deficient tumors while sparing p53-proficient cells. CHK1 inhibitors sensitize tumors to a variety of DNA-damaging agents or antimetabolites in preclinical models and are being evaluated in early phase clinical trials. In this review, we summarize recent advances and controversies in the development and application of CHK1 inhibitors as cancer therapeutics.

A phase II study of cell cycle inhibitor UCN-01 in patients with metastatic melanoma: a California Cancer Consortium trial

BACKGROUND

Genetic abnormalities in cell cycle control are common in malignant melanoma. UCN-01 (7-hydroxystaurosporine) is an investigational agent that exhibits antitumor activity by perturbing the cancer cell cycle. A patient with advanced melanoma experienced a partial response in a phase I trial of single agent UCN-01. We sought to determine the activity of UCN-01 against refractory metastatic melanoma in a phase II study. Patients and methods Patients with advanced melanoma received UCN-01 at 90 mg/m(2) over 3 h on cycle 1, reduced to 45 mg/m(2) over 3 h for subsequent cycles, every 21 days. Primary endpoint was tumor response. Secondary endpoints included progression-free survival (PFS) and overall survival (OS). A two-stage (17 + 16), single arm phase II design was employed. A true response rate of ≥ 20% (i.e., at least one responder in the first stage, or at least four responders overall) was to be considered promising for further development of UCN-01 in this setting. Results Seventeen patients were accrued in the first stage. One patient was inevaluable for response. Four (24%) patients had stable disease, and 12 (71%) had disease progression. As there were no responders in the first stage, the study was closed to further accrual. Median PFS was 1.3 months (95% CI, 1.2-3.0) while median OS was 7.3 months (95% CI, 3.4-18.4). One-year and two year OS rates were 41% and 12%, respectively. A median of two cycles were delivered (range, 1-18). Grade 3 treatment-related toxicities include hyperglycemia (N = 2), fatigue (N = 1), and diarrhea (N = 1). One patient experienced grade 4 creatinine elevation and grade 4 anemia possibly due to UCN-01. No dose modification was required as these patients had disease progression. Conclusion Although well tolerated, UCN-01 as a single agent did not have sufficient clinical activity to warrant further study in refractory melanoma.

A Phase 1 study of UCN-01 in combination with irinotecan in patients with resistant solid tumor malignancies

PURPOSE

UCN-01 (7-hydroxystaurosporine) is a multi-targeted protein kinase inhibitor that exhibits synergistic activity with DNA-damaging agents in preclinical studies. We conducted a Phase I study to determine the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), pharmacokinetic, and pharmacodynamic effects of UCN-01 and irinotecan in patients with resistant solid tumors.

EXPERIMENTAL DESIGN

Patients received irinotecan (75-125 mg/m(2) IV on days 1, 8, 15, 22) and UCN-01 (50-90 mg/m(2) IV on day 2 and 25-45 mg/m(2) on day 23 and subsequent doses) every 42 days. Blood for pharmacokinetics of UCN-01 and irinotecan, and blood, normal rectal mucosa, and tumor biopsies for pharmacodynamic studies were obtained.

RESULTS

Twenty-five patients enrolled to 5 dose levels. The MTD was irinotecan 125 mg/m(2) on days 1, 8, 15, 22 and UCN-01 70 mg/m(2) on day 2 and 35 mg/m(2) on day 23. DLTs included grade 3 diarrhea/dehydration and dyspnea. UCN-01 had a prolonged half-life and a low clearance rate. There was a significant reduction in SN-38 C(max) and aminopentanocarboxylic acid (APC) and SN-38 glucuronide half-lives. Phosphorylated ribosomal protein S6 was reduced in blood, normal rectal mucosa, and tumor biopsies at 24 h post-UCN-01. Two partial responses were observed in women with ER, PgR, and HER2-negative breast cancers (TBNC). Both tumors were defective for p53. Twelve patients had stable disease (mean duration 18 weeks, range 7-30 weeks).

CONCLUSION

UCN-01 and irinotecan demonstrated acceptable toxicity and target inhibition. Anti-tumor activity was observed and a study of this combination in women with TNBC is underway.

The release of microparticles by Jurkat leukemia T cells treated with staurosporine and related kinase inhibitors to induce apoptosis

Microparticles (MPs) are small membrane-bound vesicles released from cells undergoing activation or cell death. These particles display potent biological activities that can impact on physiologic and pathologic processes. Previous studies with the Jurkat T leukemia cell line demonstrated that staurosporine (STS) induces the release of MPs as cells undergo apoptosis. To investigate further this process, we tested the effects of STS, its analogue, 7-hydroxystaurosporine (UCN-01), and other protein kinase C (PKC) and cyclin-dependent kinase (CDK) inhibitors. FACS analysis was used to assess MP release. Results of these studies indicate that STS and UCN-01 induce MP release by Jurkat cells; in contrast, other PKC and CDK inhibitors failed to induce comparable release, suggesting that release does not result from simple inhibition of either kinase alone. Time course experiments indicated that STS-induced particle release occurred as early as 2 h after treatment, with the early release MPs displaying low levels of binding of annexin V and propidium iodide (PI). Early-release MPs, however, matured in culture to an annexin V- and PI-positive phenotype. Together, these results indicate that STS and UCN-01 induce MPs that are phenotypically distinct and reflect specific patterns of kinase inhibition during apoptosis.

Prospects for the Use of ATR Inhibitors to Treat Cancer

ATR is an apical kinase in one of the DNA-damage induced checkpoint pathways. Despite the development of inhibitors of kinases structurally related to ATR, as well as inhibitors of the ATR substrate Chk1, no ATR inhibitors have yet been developed. Here we review the effects of ATR downregulation in cancer cells and discuss the potential for development of ATR inhibitors for clinical use.

Selective disruption of insulin-like growth factor-1 (IGF-1) signaling via phosphoinositide-dependent kinase-1 prevents the protective effect of IGF-1 on human cancer cell death

Insulin-like growth factor-1 (IGF-1) signaling system exerts a broad antiapoptotic function and plays a crucial role in resistance to anticancer therapies. Exposure of MCF-7 breast cancer cells to IGF-1 rapidly and transiently induced tyrosine phosphorylation and activation of phosphoinositide-dependent kinase-1 (PDK1). This was paralleled by Akt/protein kinase B and protein kinase C-zeta phosphorylation, at Thr(308) and Thr(410), respectively. IGF-1 treatment also enhanced PDK1 interaction with IGF-1 receptor (IGF-1R) in intact MCF-7 cells. Pulldown assays revealed that PDK1 bound IGF-1R in vitro and that the region encompassing amino acids 51-359 of PDK1 was necessary for the interaction. Synthetic peptides corresponding to IGF-1R C terminus amino acids 1295-1337 (C43) and to PDK1 amino acids 114-141 reduced in vitro IGF-1R/PDK1 interaction in a concentration-dependent manner. Loading of fluoresceinated-C43 (fluorescein isothiocyanate (FITC)-C43) into MCF-7 cells significantly reduced IGF-1R/PDK1 interaction and phosphorylation of PDK1 substrates. Moreover, FITC-C43 intracellular loading reverted the protective effect of IGF-1 on growth factor deprivation-induced cell death. Finally, the inhibition of IGF-1R/PDK1 interaction and signaling by FITC-C43 was accompanied by 2-fold enhanced killing capacity of cetuximab in human GEO colon adenocarcinoma cells and was sufficient to restore cell death in cetuximab-resistant cell clones. Thus, disruption of PDK1 interaction with IGF-1R reduces IGF-1 survival effects in cancer cells and may enhance cell death by anticancer agents.

Radiotherapy in conjunction with 7-hydroxystaurosporine: a multimodal approach with tumor pO2 as a potential marker of therapeutic response

Checkpoint inhibitors potentially could be used to enhance cell killing by DNA-targeted therapeutic modalities such as radiotherapy. UCN-01 (7-hydroxystaurosporine) inhibits S and G2 checkpoint arrest in the cells of various malignant cell lines and has been investigated in combination with chemotherapy. However, little is known about its potential use in combination with radiotherapy. We report the effect of 20 Gy radiation given in conjunction with UCN-01 on the pO2 and growth of subcutaneous RIF-1 tumors. Multisite EPR oximetry was used for repeated, non-invasive tumor pO2 measurements. The effect of UCN-01 and/or 20 Gy on tumor pO2 and tumor volume was investigated to determine therapeutic outcomes. Untreated RIF-1 tumors were hypoxic with a tissue pO2 of 5-7 mmHg. Treatment with 20 Gy or UCN-01 significantly reduced tumor growth, and a modest increase in tumor pO2 was observed in tumors treated with 20 Gy. However, irradiation with 20 Gy 12 h after UCN-01 treatment resulted in a significant inhibition of tumor growth and a significant increase in tumor pO2 to 16-28 mmHg from day 1 onward compared to the control, UCN-01 or 20-Gy groups. Treatment with UCN-01 12 h after 20 Gy also led to a similar growth inhibition of the tumors and a similar increase in tumor pO2. The changes in tumor pO2 observed after the treatment correlated inversely with the tumor volume in the groups receiving UCN-01 with 20 Gy. This multimodal approach could be used to enhance the outcome of radiotherapy. Furthermore, tumor pO2 could be a potential marker of therapeutic response.

A phase I trial of UCN-01 and prednisone in patients with refractory solid tumors and lymphomas

PURPOSE

UCN-01 potently inhibits protein kinase C, phosphatidylinositide-dependent kinase-1, and checkpoint kinase 1, which are involved in regulating cell cycle progression. We designed a phase I study to determine the maximum tolerated dose (MTD) of UCN-01 with prednisone in patients with advanced malignancies.

METHODS

UCN-01 was administered as a continuous intravenous infusion over 72 h in cycle 1 and 36 h in subsequent cycles. Prednisone was given orally at 60 mg/m(2) per day for five consecutive days within each 28-day cycle. Standard dose escalation was employed, and MTD was defined as the dose at which no more than one of six patients experienced a dose-limiting toxicity (DLT). Plasma pharmacokinetics of UCN-01 were assessed.

RESULTS

Fifteen patients received a total of 55 courses of treatment. The MTD and the recommended phase II dose of UCN-01 in this combination is 72 mg/m(2) total dose over 72 h for cycle 1 followed by 36 mg/m(2) per cycle over 36 h. All patients experienced hyperglycemia but responded to insulin treatment. Hypophosphatemia was a DLT in two patients. There were no cumulative toxicities. No objective responses were observed, but five patients had stable disease, including two patients with lymphoid malignancies who had prolonged disease stabilizations. UCN-01 has a long terminal half-life and low clearance; there was wide inter-patient variability in peak concentrations.

CONCLUSION

UCN-01 can be safely administered in combination with prednisone without unacceptable toxicity. The prolonged stable disease in two patients with lymphoid malignancies is a proof of principle for the evaluation of cyclin-dependent kinase inhibitors in oncology.

Identification of potential therapeutic targets in malignant mesothelioma using cell-cycle gene expression analysis

Cell-cycle defects are responsible for cancer onset and growth. We studied the expression profile of 60 genes involved in cell cycle in a series of malignant mesotheliomas (MMs), normal pleural tissues, and MM cell cultures using a quantitative polymerase chain reaction-based, low-density array. Nine genes were significantly deregulated in MMs compared with normal controls. Seven genes were overexpressed in MMs, including the following: CDKN2C, cdc6, cyclin H, cyclin B1, CDC2, FoxM1, and Chk1, whereas Ube1L and cyclin D2 were underexpressed. Chk1 is a principal mediator of cell-cycle checkpoints in response to genotoxic stress. We confirmed the overexpression of Chk1 in an independent set of 87 MMs by immunohistochemistry using tissue microarrays. To determine whether Chk1 down-regulation would affect cell-cycle control and cell survival, we transfected either control or Chk1 siRNA into two mesothelioma cell lines and a nontumorigenic (Met5a) cell line. Results showed that Chk1 knockdown increased the apoptotic fraction of MM cells and induced an S phase block in Met5a cells. Furthermore, Chk1 silencing sensitized p53-null MM cells to both an S phase block and apoptosis in the presence of doxorubicin. Our results indicate that cell-cycle gene expression analysis by quantitative polymerase chain reaction can identify potential targets for novel therapies. Chk1 knockdown could provide a novel therapeutic approach to arrest cell-cycle progression in MM cells, thus increasing the rate of cell death.

New combination therapies with cell-cycle agents

Cancer cells have deregulated cell-cycle progression with overexpression of positive regulators and inhibition of negative regulators, giving them unlimited replication potential. Therefore, development of agents targeting the deregulated cell cycle has been considered as an ideal strategy for cancer therapy. Cell-cycle-based agents have been categorized as cyclin-dependent kinase inhibitors, Cdc25 inhibitors, checkpoint inhibitors and mitotic inhibitors. These drugs have demonstrated preclinical efficacy, but their efficacy in the clinic has been modest and has been hampered by various side effects. Alternatively, their combination with chemotherapeutic drugs has been studied in different preclinical and clinical settings. Initial reports from these combination studies have been encouraging and suggest that combined drugs may be useful in lowering cancer burden.