Selective MCL-1 inhibitor ABBV-467 is efficacious in tumor models but is associated with cardiac troponin increases in patients.

BACKGROUND: MCL-1 is a prosurvival B-cell lymphoma 2 family protein that plays a critical role in tumor maintenance and survival and can act as a resistance factor to multiple anticancer therapies. Herein, we describe the generation and characterization of the highly potent and selective MCL-1 inhibitor ABBV-467 and present findings from a first-in-human trial that included patients with relapsed/refractory multiple myeloma (NCT04178902). METHODS: Binding of ABBV-467 to human MCL-1 was assessed in multiple cell lines. The ability of ABBV-467 to induce tumor growth inhibition was investigated in xenograft models of human multiple myeloma and acute myelogenous leukemia. The first-in-human study was a multicenter, open-label, dose-escalation study assessing safety, pharmacokinetics, and efficacy of ABBV-467 monotherapy. RESULTS: Here we show that administration of ABBV-467 to MCL-1-dependent tumor cell lines triggers rapid and mechanism-based apoptosis. In vivo, intermittent dosing of ABBV-467 as monotherapy or in combination with venetoclax inhibits the growth of xenografts from human hematologic cancers. Results from a clinical trial evaluating ABBV-467 in patients with multiple myeloma based on these preclinical data indicate that treatment with ABBV-467 can result in disease control (seen in 1 patient), but may also cause increases in cardiac troponin levels in the plasma in some patients (seen in 4 of 8 patients), without other corresponding cardiac findings. CONCLUSIONS: The selectivity of ABBV-467 suggests that treatment-induced troponin release is a consequence of MCL-1 inhibition and therefore may represent a class effect of MCL-1 inhibitors in human patients.

Apoptosis is a type of cell death that removes abnormal cells from the body. Cancer cells can have increased levels of MCL-1, a protein that helps cells survive and prevents apoptosis. ABBV-467 is a new drug that blocks the action of MCL-1 (an MCL-1 inhibitor) and could promote apoptosis. In animal models, ABBV-467 led to cancer cell death and delayed tumor growth. ABBV-467 was also studied in a clinical trial in 8 patients with multiple myeloma, a blood cancer. In 1 patient, ABBV-467 treatment prevented the cancer from getting any worse for 8 months. However, in 4 out of 8 patients ABBV-467 increased the levels of troponin, a protein associated with damage to the heart. This concerning side effect may impact the future development of MCL-1 inhibitors as anticancer drugs.

Colorectal cancer presenting as bone metastasis.

INTRODUCTION: Bone metastasis is a rare site of metastasis, seen in only 3.7-11% of clinical cases. Isolated bone involvement has been reported very rarely in literature. Moreover, the patients who have bone metastasis at presentation are even rare. OBJECTIVES: To discuss the demographic characteristics, carcinoembryonic antigen (CEA) levels, pattern of bone involvement, and their correlation with survival in patients of colorectal cancer that have bone metastasis at the time of presentation. MATERIALS AND METHODS: Retrospectively, tumor registry was analyzed for the cases of colorectal cancer presenting with bone metastasis between 2008 and 2013. Survival curves were generated by Kaplan-Meier method and analyzed using the log-rank test. RESULTS: Ten such patients were identified (male:female = 7:3) of the total 410 patients. Median age was 41 years (22-50 years). All patients were Conclusions: In this study, the patients of colorectal cancer presenting with bone metastasis were of male sex and younger age. The factors that were associated with reduced survival were extraosseous and liver involvement.

Locally advanced oral cavity squamous cell carcinoma: Barriers related to effective treatment.

BACKGROUND: Oral cavity cancer is a significant health problem in India. Majority of patients present with locally advanced disease requiring multimodality treatment. Compliance to recommended treatment is an important factor affecting outcome. AIMS: The aim was to evaluate the outcome of locally advanced oral cavity cancer patients with regards to treatment adherence and to assess reasons of noncompliance. MATERIALS AND METHODS: This was a prospective observational study. We included patients referred to Department of Medical Oncology for induction chemotherapy in view of locally advanced oral cavity cancer. RESULTS: Only 15 (26%) patients completed planned treatment schedule. Their 1 year overall survival was 93%. The remaining 43 patients who received inadequate treatment had a dismal 21% 1 year overall survival. Illiteracy, poverty, long waiting list for surgery, prolonged delay for health scheme treatment plan approval and dissatisfaction with attitude of hospital staffs are major barriers related to effective treatment of these patients. CONCLUSIONS: A detailed discussion with patient and their relatives regarding recommended treatment, proper implementation of health schemes, increasing trained manpower to avoid long waiting list for surgery, provision of additional financial support for family member accompanying the patient and a sympathetic approach toward patients are needed to help these patients overcome the battle.

Presynaptic BK channel localization is dependent on the hierarchical organization of alpha-catulin and dystrobrevin and fine-tuned by CaV2 calcium channels.

BACKGROUND: Large conductance, calcium-activated BK channels regulate many important physiological processes, including smooth muscle excitation, hormone release and synaptic transmission. The biological roles of these channels hinge on their unique ability to respond synergistically to both voltage and cytosolic calcium elevations. Because calcium influx is meticulously regulated both spatially and temporally, the localization of BK channels near calcium channels is critical for their proper function. However, the mechanism underlying BK channel localization near calcium channels is not fully understood. RESULTS: We show here that in C. elegans the localization of SLO-1/BK channels to presynaptic terminals, where UNC-2/CaV2 calcium channels regulate neurotransmitter release, is controlled by the hierarchical organization of CTN-1/α-catulin and DYB-1/dystrobrevin, two proteins that interact with cortical cytoskeletal proteins. CTN-1 organizes a macromolecular SLO-1 channel complex at presynaptic terminals by direct physical interaction. DYB-1 contributes to the maintenance or stabilization of the complex at presynaptic terminals by interacting with CTN-1. We also show that SLO-1 channels are functionally coupled with UNC-2 calcium channels, and that normal localization of SLO-1 to presynaptic terminals requires UNC-2. In the absence of UNC-2, SLO-1 clusters lose the localization specificity, thus accumulating inside and outside of presynaptic terminals. Moreover, CTN-1 is also similarly localized in unc-2 mutants, consistent with the direct interaction between CTN-1 and SLO-1. However, localization of UNC-2 at the presynaptic terminals is not dependent on either CTN-1 or SLO-1. Taken together, our data strongly suggest that the absence of UNC-2 indirectly influences SLO-1 localization via the reorganization of cytoskeletal proteins. CONCLUSION: CTN-1 and DYB-1, which interact with cortical cytoskeletal proteins, are required for the presynaptic punctate localization of SLO-1 in a hierarchical manner. In addition, UNC-2 calcium channels indirectly control the fidelity of SLO-1 puncta localization at presynaptic terminals. We suggest that the absence of UNC-2 leads to the reorganization of the cytoskeletal structure that includes CTN-1, which in turn influences SLO-1 puncta localization.

Lenalidomide in relapsed refractory non-Hodgkin's lymphoma: An Indian perspective.

BACKGROUND: Lenalidomide an immunomodulatory agent has shown activity in relapsed/refractory lymphoma. This study was conducted to evaluate its efficacy and optimal dose in Indian patients with relapsed/refractory lymphoma who were unable or unwilling to undergo autologous hematopoietic stem cell transplant. MATERIALS AND METHODS: Patients received oral lenalidomide at 20 mg on days 1-21 every 28 days until disease progression or unacceptable toxicity. RESULTS: A total of 25 patients received lenalidomide at a starting dose of 20 mg. Majority of patients were diffuse large B-cell lymphoma (DLBCL). The overall response rate (ORR) was 48%, with 16% achieved complete remission (CR)/unconfirmed CR (CRu), 32% partial response (PR) and 16% stable disease (SD) Among patients with DLBCL the ORR was of 33.3%; with CR/CRu 20%, PR (13.3%), 20% had SD, progressive disease (PD) was seen in seven patients (46.6%). All follicular lymphoma patients responded to treatment, with CR in one patient and PR in other two. Among patients with mantle cell lymphoma, ORR was 75% with PR in (75%) and SD in 25%. One case of transformed lymphoma had a PR and peripheral T-cell lymphoma had no response to treatment. The median duration of response was 8.5 months, with a time to response of 3 months. Median progression free survival was not reached in responding patients. CONCLUSION: Lenalidomide is an effective treatment option in relapsed refractory non hodgkin's lymphoma.

Anaplastic large cell lymphoma: a single institution experience from India.

BACKGROUND: Systemic anaplastic large cell lymphoma (ALCL) accounts for 2-8% of non-Hodgkin's lymphoma in adults and 10-15% in children. While there is ample data in the world literature about the clinical features and outcome of this disease, prognosis in Indian patients is largely unknown. OBJECTIVE: To study the clinical, pathologic profile and outcome ALCL. MATERIALS AND METHODS: Fifty patients who had pathologically proven diagnosis of systemic ALCL at our institute from June 2003 to May 2011 were included for retrospective analysis. This included 30 cases of anaplastic lymphoma kinase+ (ALK+), ALCL and 20 cases of anaplastic lymphoma kinase- (ALK-), ALCL. The hospital protocol for treatment of these patients included CHOP chemotherapy regimen in >15 years of age and MCP842 protocol with vinblastine for 1 year in <15 years of age. Event free survival was noted. These outcomes were correlated with ALK status, International Prognostic Index (IPI) score, and stage at presentation. RESULTS: At a median follow-up of 36 months (range: 6-72 months) ALK- ALCL had a poor outcome. The 3 year event free survival in pediatric ALCL was 66.7%. In adults, this was 60% ALK+ ALCL was 60% and 20% in ALK- ALCL. CONCLUSIONS: Systemic ALCL is an aggressive disease. CD3 + positivity is commonly seen in ALK- ALCL and ALK+, epithelial membrane antigen + positivity is seen in ALK+ ALCL. ALK- ALCL, advanced stage III, IV and high IPI score were associated with poor prognosis. The demographic profile and outcome in our study was similar to the world literature. With new drugs like crizotinib and brentuximab vedotin the future looks very promising.

Chronic myeloid leukemia in children and adolescents: results of treatment with imatinib mesylate.

Chronic myeloid leukemia (CML) is a rare disease in children, accounting for 2-3% of leukemias in this age group. Few studies have reported on efficacy of imatinib in childhood CML. The purpose of this retrospective study was to determine the efficacy of imatinib in children. A total of 43 patients from age 7 years to 20 years with newly diagnosed CML received imatinib daily at 260 mg/m(2). Response rates, survival and toxicity were evaluated. The median follow-up was 43 months. All patients achieved a complete hematological response. Twenty-five (58.1%) patients achieved a complete cytogenetic response and 18 (41.9%) achieved a major molecular response at any time during their follow-up period. Both overall survival and progression-free survival at 43 months' median follow-up were 100%. Event-free survival was 92.8%. Imatinib was well tolerated. We conclude that imatinib is effective in children and adolescents with CML.

Interaction of α-catulin with dystrobrevin contributes to integrity of dystrophin complex in muscle.

The dystrophin complex is a multimolecular membrane-associated protein complex whose defects underlie many forms of muscular dystrophy. The dystrophin complex is postulated to function as a structural element that stabilizes the cell membrane by linking the contractile apparatus to the extracellular matrix. A better understanding of how this complex is organized and localized will improve our knowledge of the pathogenic mechanisms of diseases that involve the dystrophin complex. In a Caenorhabditis elegans genetic study, we demonstrate that CTN-1/α-catulin, a cytoskeletal protein, physically interacts with DYB-1/α-dystrobrevin (a component of the dystrophin complex) and that this interaction is critical for the localization of the dystrophin complex near dense bodies, structures analogous to mammalian costameres. We further show that in mouse α-catulin is localized at the sarcolemma and neuromuscular junctions and interacts with α-dystrobrevin and that the level of α-catulin is reduced in α-dystrobrevin-deficient mouse muscle. Intriguingly, in the skeletal muscle of mdx mice lacking dystrophin, we discover that the expression of α-catulin is increased, suggesting a compensatory role of α-catulin in dystrophic muscle. Together, our study demonstrates that the interaction between α-catulin and α-dystrobrevin is evolutionarily conserved in C. elegans and mammalian muscles and strongly suggests that this interaction contributes to the integrity of the dystrophin complex.

Glutathione is essential for early embryogenesis--analysis of a glutathione synthetase knockout mouse.

Glutathione (GSH) is present in all mammalian tissues and plays a crucial role in many cellular processes. The second and final step in the synthesis involves the formation of GSH from gamma-glutamylcysteine (γ-GC) and glycine and is catalyzed by glutathione synthetase (GS). GS deficiency is a rare autosomal recessive disorder, and is present in patients with a range of phenotypes, from mild hemolytic anemia and metabolic acidosis to severe neurologic disorders or even death in infancy. The substrate for GS, γ-GC, has been suggested as playing a protective role, by substituting for GSH as an antioxidant in GS deficient patients. To examine the role of GS and GSH metabolites in development, we generated mice deficient in GSH by targeted disruption of the GS gene (Gss). Homozygous mice died before embryonic day (E) 7.5, but heterozygous mice survived with no distinct phenotype. GS protein levels and enzyme activity, as well as GSH metabolites, were investigated in multiple tissues. Protein levels and enzyme activity of GS in heterozygous mice were diminished by 50%, while GSH levels remained intact. γ-GC could not be detected in any investigated tissue. These data demonstrate that GSH is essential for mammalian development, and GSH synthesis via GS is an indispensable pathway for survival.

N-acetylcysteine amide (NACA) prevents retinal degeneration by up-regulating reduced glutathione production and reversing lipid peroxidation.

Oxidative stress plays a critical role in accelerating retinal pigment epithelial dysfunction and death in degenerative retinal diseases, including age-related macular degeneration. Given the key role of oxidative stress-induced retinal pigment epithelial cell death and secondary photoreceptor loss in the pathogenesis of age-related macular degeneration, we hypothesized that a novel thiol antioxidant, N-acetylcysteine amide (NACA), might ameliorate cellular damage and subsequent loss of vision. Treatment of human retinal pigment epithelial cells with NACA protected against oxidative stress-induced cellular injury and death. NACA acted mechanistically by scavenging existing reactive oxygen species while halting production of reactive oxygen species by reversing lipid peroxidation. Furthermore, NACA functioned by increasing the levels of reduced glutathione and the phase II detoxification enzyme glutathione peroxidase. Treatment of mice exposed to phototoxic doses of light with NACA maintained retinal pigment epithelial cell integrity and prevented outer nuclear layer cell death as examined by histopathologic methods and rescued photoreceptor function as measured by electroretinography. These observations indicate that NACA protects against oxidative stress-induced retinal pigment epithelial and photoreceptor cell death in vitro and in vivo. The data suggest that NACA may be a novel treatment in rescuing retinal function and preventing vision loss secondary to retinal degenerative diseases, including age-related macular degeneration.

Sub-chronic lead exposure alters kidney proteome profiles.

The current study examined the impact of sub-chronic lead (Pb)-exposure upon global protein profile in rodent kidney (blood Pb levels ~50 µg/dL; 5 weeks oral Pb-acetate exposure). Utilizing 2D SDS-PAGE for kidney protein separation, greater than 500 protein spots were analyzed by densitometry following background noise removal, spot alignment, and intensity filtering. Approximately 100 protein spots were identified by ESI-MS/MS with mitochondrial, chaperone, antioxidant, and Pb-binding proteins included. Forty-eight protein spots exhibited significant alterations in abundance (18 identified by ESI-MS/MS) including the increased protein abundance of ketohexokinase, enolase, protein disulfide-isomerase, lamda crystallin, lactamase, and glycerol-3-phosphate dehydrogenase. Decreased protein abundances were observed for α-2 microglobulin, glutamate cysteine ligase, prohibitin, homogentisate 1,2-dioxygenase, alpha-ETF, argininosuccinate synthetase and ATP synthase (H+ transporting). These data support the hypothesis that protein profiles in the kidney are altered following sub-chronic physiologically relevant Pb-exposure.

An alpha-catulin homologue controls neuromuscular function through localization of the dystrophin complex and BK channels in Caenorhabditis elegans.

The large conductance, voltage- and calcium-dependent potassium (BK) channel serves as a major negative feedback regulator of calcium-mediated physiological processes and has been implicated in muscle dysfunction and neurological disorders. In addition to membrane depolarization, activation of the BK channel requires a rise in cytosolic calcium. Localization of the BK channel near calcium channels is therefore critical for its function. In a genetic screen designed to isolate novel regulators of the Caenorhabditis elegans BK channel, SLO-1, we identified ctn-1, which encodes an α-catulin homologue with homology to the cytoskeletal proteins α-catenin and vinculin. ctn-1 Mutants resemble slo-1 loss-of-function mutants, as well as mutants with a compromised dystrophin complex. We determined that CTN-1 uses two distinct mechanisms to localize SLO-1 in muscles and neurons. In muscles, CTN-1 utilizes the dystrophin complex to localize SLO-1 channels near L-type calcium channels. In neurons, CTN-1 is involved in localizing SLO-1 to a specific domain independent of the dystrophin complex. Our results demonstrate that CTN-1 ensures the localization of SLO-1 within calcium nanodomains, thereby playing a crucial role in muscles and neurons.

Determination of glutathione disulfide levels in biological samples using thiol-disulfide exchanging agent, dithiothreitol.

A reverse-phase HPLC method incorporating dithiothreitol (DTT) reduction for quantitative determination of oxidized glutathione (GSSG) in biological samples is described here. This method is based on our previous enzymatic reduction technique that uses N-1-(pyrenyl) maleimide (NPM) as a derivatizing agent. In our earlier method, glutathione disulfide (GSSG) was measured by first reducing it to GSH with glutathione reductase (GR) in the presence of NADPH. However, this is a very costly and time-consuming technique. The method described here employs a common and inexpensive thiol-disulfide exchanging agent, DTT, for reduction of GSSG to GSH, followed by derivatization with NPM. The calibration curves are linear over a concentration range of 25-1250 nm (r(2) > 0.995). The coefficients of variations for intra-run precision and inter-run precision range from 0.49 to 5.10% with an accuracy range of 1.78-6.15%. The percentage of relative recovery ranges from 97.3 to 103.2%. This new method provides a simple, efficient, and cost-effective way of determining glutathione disulfide levels with a 2.5 nm limit of detection per 5 microL injection volume.

Effects of N-acetylcysteine amide (NACA), a thiol antioxidant on radiation-induced cytotoxicity in Chinese hamster ovary cells.

Ionizing radiation is known to cause tissue damage in biological systems, mainly due to its ability to produce reactive oxygen species (ROS) in cells. Many thiol antioxidants have been used previously as radioprotectors, but their application has been limited by their toxicity. In this investigation, we have explored the possible radioprotective effects of a newly synthesized thiol antioxidant, N-acetylcysteine amide (NACA), in comparison with N-acetylcysteine (NAC), a commonly used antioxidant. Protective effects of NACA and NAC were assessed using Chinese hamster ovary (CHO) cells, irradiated with 6 gray (Gy) radiation. Oxidative stress parameters, including levels of reduced glutathione (GSH), cysteine, malondialdehyde (MDA), and activities of antioxidant enzymes like glutathione peroxidase, glutathione reductase, and catalase, were measured. Results indicate that NACA was capable of restoring GSH levels in irradiated cells in a dose dependent manner. In addition, NACA prevented radiation-induced loss in cell viability. NACA further restored levels of malondialdehyde, caspase-3 activity, and antioxidant enzyme activities to control levels. Although NAC affected cells in a similar manner to NACA, its effects were not as significant. Further, NAC was also found to be cytotoxic to cells at higher concentrations, whereas NACA was non-toxic at similar concentrations. These results suggest that NACA may be able to attenuate radiation-induced cytotoxicity, possibly by its ability to provide thiols to cells.

Antioxidant and free radical scavenging properties of N-acetylcysteine amide (NACA) and comparison with N-acetylcysteine (NAC).

The antioxidant potential of N-acetylcysteine amide (NACA), also known as AD4, was assessed by employing different in vitro assays. These included reducing power, free radical scavenging capacities, peroxidation inhibiting activity through linoleic acid emulsion system and metal chelating capacity, as compared to NAC and three widely used antioxidants, alpha-tocopherol, ascorbic acid and butylated hydroxytoluene (BHT). Of the antioxidant properties that were investigated, NACA was shown to possess higher 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging ability and reducing power than NAC, at all the concentrations, whereas the scavenging ability of H(2)O(2) differed with concentration. While NACA had greater H(2)O(2) scavenging capacity at the highest concentration, NAC was better than NACA at lower concentrations. NAC and NACA had a 60% and 55% higher ability to prevent beta-carotene bleaching, respectively, as compared to control. The chelating activity of NACA was more than 50% that of the metal chelating capacity of EDTA and four and nine times that of BHT and alpha-tocopherol, respectively. When compared to NACA and NAC; alpha-tocopherol had higher DPPH scavenging abilities and BHT and alpha-tocopherol had better beta-carotene bleaching power. These findings provide evidence that the novel antioxidant, NACA, has indeed enhanced the antioxidant properties of NAC.