Cultured lymphocytes' mitochondrial genome integrity is not altered by cladribine.

Cladribine tablets are a treatment for multiple sclerosis with effects on lymphocytes, yet its mode of action has not been fully established. Here, we analyzed the effects of cladribine on mitochondrial DNA integrity in lymphocytes. We treated cultured human T-cell lines (CCRF-CEM and Jurkat) with varying concentrations of cladribine to mimic the slow cell depletion observed in treated patients. The CCRF-CEM was more susceptible to cladribine than Jurkat cells. In both cells, mitochondrial protein synthesis, mitochondrial DNA copy number, and mitochondrial cytochrome-c oxidase-I mRNA mutagenesis was not affected by cladribine, while caspase-3 cleavage was detected in Jurkat cells at 100 nM concentration. Cladribine treatment at concentrations up to 10 nM in CCRF-CEM and 100 nM in Jurkat cells did not induce significant increase in mitochondrial DNA mutations. Peripheral blood mononuclear cells from eight multiple sclerosis patients and four controls were cultured with or without an effective dose of cladribine (5 nM). However, we did not find any differences in mitochondrial DNA somatic mutations in lymphocyte subpopulations (CD4+, CD8+, and CD19+) between treated versus nontreated cells. The overall mutation rate was similar in patients and controls. When different lymphocyte subpopulations were compared, greater mitochondrial DNA mutation levels were detected in CD8+ (P = 0.014) and CD4+ (P = 0.038) as compared to CD19+ cells, these differences were independent of cladribine treatment. We conclude that T cells have more detectable mitochondrial DNA mutations than B cells, and cladribine has no detectable mutagenic effect on lymphocyte mitochondrial genome nor does it impair mitochondrial function in human T-cell lines.

Oral Cladribine Impairs Intermediate, but Not Conventional, Monocyte Transmigration in Multiple Sclerosis Patients across a Model Blood-Brain Barrier.

Multiple sclerosis (MS) is a disease in which the immune system damages components of the central nervous system (CNS), leading to the destruction of myelin and the formation of demyelinating plaques. This often occurs in episodic "attacks" precipitated by the transmigration of leukocytes across the blood-brain barrier (BBB), and repeated episodes of demyelination lead to substantial losses of axons within and removed from plaques, ultimately leading to progressive neurological dysfunction. Within leukocyte populations, macrophages and T and B lymphocytes are the predominant effectors. Among current immunotherapies, oral cladribine's impact on lymphocytes is well characterised, but little is known about its impact on other leukocytes such as monocytes and dendritic cells (DCs). The aim of this study was to determine the transmigratory ability of monocyte and DC subsets in healthy subjects and untreated and cladribine-treated relapse-remitting MS (RRMS) patients using a well-characterised model of the BBB. Peripheral blood mononuclear cells from subjects were added to an in vitro transmigration assay to assess cell migration. Our findings show that while prior treatment with oral cladribine inhibits the migration of intermediate monocytes, it has no impact on the transmigration of DC subsets. Overall, our data indicate a previously unrecognised role of cladribine on intermediate monocytes, known to accumulate in the brain active MS lesions.

Cladribine therapy for advanced and indolent systemic mastocytosis: Mayo Clinic experience in 42 consecutive cases.

We describe our single institution experience with cladribine therapy in 42 patients with systemic mastocytosis (SM): 22 advanced (adv-SM; median age 65 years, 68% males) and 20 indolent/smouldering SM (ISM/SSM; median age 56 years, 45% males); subcategories included eight aggressive, 13 associated with another haematological neoplasm, one mast cell leukaemia, 17 ISM and three SSM. Overall/major response rates were 77%/45% for adv-SM and 70%/60% for ISM/SSM, and median (range) duration of response 10 (4-75) and 46 (4-140) months respectively. A >50% reduction in bone marrow mast cell burden and serum tryptase level was documented in 63% and 67% of patients with adv-SM and 50% and 46% with ISM/SSM respectively. The presence of KIT proto-oncogene, receptor tyrosine kinase (KIT)D816V predicted response in adv-SM: 17 (90%) of 19 with and none of three without the mutation responded (P < 0·01). Treatment-emergent adverse events were mostly limited to transient cytopenias: Grade 3/4 neutropenia, thrombocytopenia, or lymphopenia occurred in 27%, 27% and 27% of patients with adv-SM, and 5%, 5% and 30% with ISM/SSM respectively. The present study provides practical information that might be considered when making treatment choices between cladribine and newer KIT-targeted therapies and identifies the absence of KITD816V as a potential marker of cladribine resistance in advanced SM; the latter observation needs confirmation in a larger study.

Cytokine Secretion Dynamics of Isolated PBMC after Cladribine Exposure in RRMS Patients.

Cladribine (CLD) treats multiple sclerosis (MS) by selectively and transiently depleting B and T cells with a secondary long-term reconstruction of the immune system. This study provides evidence of CLD's immunomodulatory role in peripheral blood mononuclear cells (PBMCs) harvested from 40 patients with untreated relapsing-remitting MS (RRMS) exposed to CLD. We quantified cytokine secretion from PBMCs isolated by density gradient centrifugation with Ficoll−Paque using xMAP technology on a FlexMap 3D analyzer with a highly sensitive multiplex immunoassay kit. The PBMC secretory profile was evaluated with and without CLD exposure. PBMCs isolated from patients with RRMS for ≤12 months had significantly higher IL-4 but significantly lower IFN-γ and TNF-α secretion after CLD exposure. PBMCs isolated from patients with RRMS for >12 months had altered inflammatory ratios toward an anti-inflammatory profile and increased IL-4 but decreased TNF-α secretion after CLD exposure. CLD induced nonsignificant changes in IL-17 secretion in both RRMS groups. Our findings reaffirm CLD's immunomodulatory effect that induces an anti-inflammatory phenotype.

Long-term results of low-intensity chemotherapy with clofarabine or cladribine combined with low-dose cytarabine alternating with decitabine in older patients with newly diagnosed acute myeloid leukemia.

The treatment of older patients with newly diagnosed acute myeloid leukemia (AML) using intensive chemotherapy is associated with treatment intolerance and poor survival. We evaluated two new lower-intensity regimens with clofarabine (n = 119) or cladribine (n = 129) combined with low-dose cytarabine (LDAC) alternating with decitabine. We reviewed response rates by subgroup and long term outcomes of 248 patients with newly diagnosed non core-binding-factor AML treated on two clinical trials investigating double nucleoside-analogue therapy (DNT) alternating with HMA from October, 2008 to April, 2018. Of 248 patients with a median age of 69 years (range, 49-85 years), 102 patients (41%) were ≥ 70 years, and 108 (44%) had adverse karyotype. Overall, 164 patients (66%) responded: 147 (59%) complete remission (CR) and 17 (7%) CR with incomplete count recovery (CRi). With a median follow up of 60 months, median relapse-free and overall survival (OS) were 10.8 and 12.5 months, respectively. The 2-year OS was 29%. Among patients with normal karyotype, the CR/CRi rate was 79% and the median OS 19.9 months. High response rates and OS were observed in patients with mutations in NPM1, FLT3, IDH2, and RUNX1. The 4- and 8-week mortality rates were 2% and 11%, respectively. The backbone of clofarabine or cladribine and LDAC alternating with decitabine was effective and safe for the treatment of older patients with newly diagnosed AML. Incorporating targeted therapies could extend the efficacy of this approach and provide more curative therapeutic options in this AML population.

Cladribine Induces ATF4 Mediated Apoptosis and Synergizes with SAHA in Diffuse Large B-Cell Lymphoma Cells.

Cladribine is a purine nucleoside analog used to treat B-cell chronic lymphocytic leukemia and hairy cell leukemia, also functions as an inhibitor of DNA synthesis to block the repair of the damaged DNA. The therapeutic role of cladribine against diffuse large B-cell lymphoma cells (DLBCL) is still undefined. In the present study, we demonstrated that cladribine inhibited cell proliferation and induced G1 phase arrest in human DLBCL cells. Furthermore, we showed that cladribine induced apoptosis by decreasing the expression of c-FLIPL and increasing the expression of DR4 and the cleaved form of caspase8. Cladribine also upregulated the expression of Bax, and downregulated the expression of Mcl-1 and Bcl-2 in a dose-dependent manner. It also activated endoplasmic reticulum (ER) stress, and ATF4 expression was required for cladribine induced apoptosis. Also, we showed that suberoylanilide hydroxamic acid (SAHA) enhanced the pro-apoptotic role of cladribine. Collectively, cladribine activated extrinsic and intrinsic apoptotic signaling pathways via stimulating ER stress signaling pathway and eliciting synergistic effect with SAHA in DLBCL cells.

Efficacy of Cladribine Tablets in high disease activity subgroups of patients with relapsing multiple sclerosis: A post hoc analysis of the CLARITY study.

BACKGROUND: In the CLARITY (CLAdRIbine Tablets treating multiple sclerosis orallY) study, Cladribine Tablets significantly improved clinical and magnetic resonance imaging (MRI) outcomes (vs placebo) in patients with relapsing-remitting multiple sclerosis. OBJECTIVE: Describe two clinically relevant definitions for patients with high disease activity (HDA) at baseline of the CLARITY study (utility verified in patients receiving placebo) and assess the treatment effects of Cladribine Tablets 3.5 mg/kg compared with the overall study population. METHODS: Outcomes of patients randomised to Cladribine Tablets 3.5 mg/kg or placebo were analysed for subgroups using HDA definitions based on high relapse activity (HRA; patients with ⩾2 relapses during the year prior to study entry, whether on DMD treatment or not) or HRA plus disease activity on treatment (HRA + DAT; patients with ⩾2 relapses during the year prior to study entry, whether on DMD treatment or not, PLUS patients with ⩾1 relapse during the year prior to study entry while on therapy with other DMDs and ⩾1 T1 Gd+ or ⩾9 T2 lesions). RESULTS: In the overall population, Cladribine Tablets 3.5 mg/kg reduced the risk of 6-month-confirmed Expanded Disability Status Scale (EDSS) worsening by 47% vs placebo. A risk reduction of 82% vs placebo was seen in both the HRA and HRA + DAT subgroups (vs 19% for non-HRA and 18% for non-HRA + DAT), indicating greater responsiveness to Cladribine Tablets 3.5 mg/kg in patients with HDA. There were consistent results for other efficacy endpoints. The safety profile in HDA patients was consistent with the overall CLARITY population. CONCLUSION: Patients with HDA showed clinical and MRI responses to Cladribine Tablets 3.5 mg/kg that were generally better than, or at least comparable with, the outcomes seen in the overall CLARITY population.

Cladribine: mechanisms and mysteries in multiple sclerosis.

OBJECTIVES: The aims of this manuscript were to review the evidence for the efficacy and safety of cladribine in multiple sclerosis (MS) and to review the molecular and cellular mechanisms by which cladribine acts as a disease-modifying therapy in MS. METHODS: This is a narrative review of the available clinical and preclinical data on the use of cladribine in MS. RESULTS: Clinical trial data argue strongly that cladribine is a safe and effective therapy for relapsing MS and that it may also be beneficial in progressive MS. The pharmacology of cladribine explains how it is selectively toxic towards lymphocytes. Immunophenotyping studies show that cladribine depletes lymphocyte populations in vivo with a predilection for B cells. In vitro studies demonstrate that cladribine also exerts immunomodulatory influences over innate and adaptive immunity. CONCLUSIONS: Cladribine is a safe and effective form of induction therapy for relapsing MS. Its mechanism of benefit is not fully understood but the most striking action is selective, long-lasting, depletion of B lymphocytes with a particular predilection for memory B cells. The in vivo relevance of its other immunomodulatory actions is unknown. The hypothesis that cladribine's action of benefit is to deplete memory B cells is important: if correct, it implies that selective targeting of this cell population and sparing of other lymphocytes could modify disease activity without predisposing to immunosuppression-related complications.

Reduced brain atrophy rates are associated with lower risk of disability progression in patients with relapsing multiple sclerosis treated with cladribine tablets.

BACKGROUND: Neuroimaging studies have used magnetic resonance imaging-derived methods to assess brain volume loss in multiple sclerosis (MS) as a reliable measure of diffuse tissue damage. METHODS: In the CLARITY study ( ClinicalTrials.gov NCT00213135), the effect of 2 years' treatment with cladribine tablets on annualized percentage brain volume change (PBVC/y) was evaluated in patients with relapsing MS (RMS). RESULTS: Compared with placebo (-0.70% ± 0.79), PBVC/y was reduced in patients treated with cladribine tablets 3.5 mg/kg (-0.56% ± 0.68, p = 0.010) and 5.25 mg/kg (-0.57% ± 0.72, p = 0.019). After adjusting for treatment group, PBVC/y showed a significant correlation with the cumulative probability of disability progression (HR = 0.67, 95% CI = 0.571, 0.787; p < 0.001), with patients with lower PBVC/y showing the highest probability of remaining free from disability progression at 2 years and vice versa. CONCLUSIONS: Cladribine tablets given annually for 2 years in short-duration courses in patients with RMS in the CLARITY study significantly reduced brain atrophy in comparison with placebo treatment, with residual rates in treated patients being close to the physiological rates.

Synthesis of novel 6-substituted amino-9-(ß-d-ribofuranosyl)purine analogs and their bioactivities on human epithelial cancer cells.

New nucleoside derivatives with nitrogen substitution at the C-6 position were prepared and screened initially for their in vitro anticancer bioactivity against human epithelial cancer cells (liver Huh7, colon HCT116, breast MCF7) by the NCI-sulforhodamine B assay. N6-(4-trifluoromethylphenyl)piperazine analog (27) exhibited promising cytotoxic activity. The compound 27 was more cytotoxic (IC50 = 1-4 µM) than 5-FU, fludarabine on Huh7, HCT116 and MCF7 cell lines. The most potent nucleosides (11, 13, 16, 18, 19, 21, 27, 28) were further screened for their cytotoxicity in hepatocellular cancer cell lines. The compound 27 demonstrated the highest cytotoxic activity against Huh7, Mahlavu and FOCUS cells (IC50 = 1, 3 and 1 µM respectively). Physicochemical properties, drug-likeness, and drug score profiles of the molecules showed that they are estimated to be orally bioavailable. The results pointed that the novel derivatives would be potential drug candidates.

Addition of cladribine to the standard induction treatment improves outcomes in a subset of elderly acute myeloid leukemia patients. Results of a randomized Polish Adult Leukemia Group (PALG) phase II trial.

Intensive induction chemotherapy using anthracycline and cytarabine backbone is considered the most effective upfront therapy in physically fit older patients with acute myeloid leukemia (AML). However, outcomes of the standard induction in elderly AML are inferior to those observed in younger patients, and they are still unsatisfactory. As addition of cladribine to the standard induction therapy is known to improve outcome in younger AML patients. The present randomized phase II study compares efficacy and toxicity of the DAC (daunorubicin plus cytarabine plus cladribine) regimen with the standard DA (daunorubicin plus cytarabine) regimen in the newly diagnosed AML patients over 60 years of age. A total of 171 patients were enrolled in the study (DA, 86; DAC, 85). A trend toward higher complete remission (CR) was observed in the DAC arm compared to the DA arm (44% vs. 34%; P = .19), which did not lead to improved median overall survival, which in the case of the DAC group was 8.6 months compared to in 9.1 months in the DA group (P = .64). However, DAC appeared to be superior in the group of patients aged 60-65 (CR rate: DAC 51% vs. DA 29%; P = .02). What is more, a subgroup of patients, with good and intermediate karyotypes, benefited from addition of cladribine also in terms of overall survival (P = .02). No differences in hematological and nonhematological toxicity between the DA and DAC regimens were observed.

Synergistic Activity of an Antimetabolite Drug and Tyrosine Kinase Inhibitors against Breast Cancer Cells.

Antimetabolite drugs, including the adenosine deaminase inhibitor cladribine, have been shown to induce apoptosis in a variety of cancer cells, and have been widely used in clinical trials of various cancers in conjunction with tyrosine kinase inhibitors (TKIs). Combination treatment with cladribine and gefitinib or dasatinib is expected to have a synergistic inhibitory effect on breast cancer cell growth. Our results demonstrated that the combination treatment had synergistic activity against human breast cancer (MCF-7) cells, enhanced G2/M cell arrest and reactive oxygen species (ROS) generation, and increased the loss of mitochondrial membrane potential and cell apoptosis. In addition, the combination treatment decreased Bcl-2 expression. Our results demonstrated that cladribine in combination with gefitinib or dasatinib exerted synergistic anticancer effects on MCF-7 cells by inducing cell cycle arrest, ROS production and apoptosis through the mitochondria-mediated intrinsic pathway.

Synthesis and Functional Investigations of Computer Designed Novel Cladribine-Like Compounds for the Treatment of Multiple Sclerosis.

Cladribine (2-CdA) is used as an anti-cancer drug but is currently studied as a potential treatment for use in relapsing-remitting multiple sclerosis (MS). In this study, we computer designed, synthesized, and characterized two novel derivatives of 2-CdA, K1-5d and K2-4c, and investigated their underlying mechanism of beneficial effect using the CCRF-CEM and RAJI cell lines. For this purpose, we first determined their effect on MS and DNA damage and repair-related gene expression profiles using custom arrays along with 2-CdA treatment at non-toxic doses. Then, we determined whether cells underwent apoptosis after treatment with 2-CdA, K1-5d, and K2-4c in CCRF-CEM and RAJI cells, using the DNA fragmentation assay. It was found that both derivatives modulated the expression of the pathway-related genes that are important in inflammatory signaling, apoptosis, ATM/ATR, double-strand break repair, and the cell cycle. Furthermore, 2-CdA, K1-5d, and K2-4c significantly activated apoptosis in both cell lines. In summary, our data demonstrate that although both derivatives act as anti-inflammatory and apoptotic agents, inducing the accumulation of DNA strand breaks and activating the ultimate tumor suppressor p53 in T and B lymphocytes, the K1-5d derivative has shown more promising activities for further studies.

Suberoylanilide hydroxamic acid (SAHA) and cladribine synergistically induce apoptosis in NK-LGL leukaemia.

Natural killer (NK) large granular lymphocyte (LGL) leukaemia features a clonal proliferation of CD3(-) NK cells that can be classified into either aggressive or chronic categories. The NKL cell line, derived from an aggressive Asian NK cell leukaemia, and patient samples from chronic NK-LGL leukaemia were used in our study to probe for synergistic efficacy of the epigenetic drugs vorinostat (SAHA) and cladribine in this disease. We demonstrate that histone deacetylases (HDACs) are over-expressed in both aggressive and chronic NK leukaemia. Administration of the HDAC inhibitor SAHA reduces class I and II HDAC expression and enhances histone acetylation in leukaemic NK cells. In vitro combination treatment with SAHA and cladribine dose-dependently exerts synergistic cytotoxic and apoptotic effects on leukaemic NK cells. Expression profiling of apoptotic regulatory genes suggests that both compounds led to caspase-dependent apoptosis through activation of intrinsic mitochondrial and extrinsic death receptor pathways. Collectively, these data show that combined epigenetic therapy, using HDAC and DNA methyltransferase inhibitors, may be a promising therapeutic approach for NK-LGL leukaemia.

Cladribine Analogues via O6-(Benzotriazolyl) Derivatives of Guanine Nucleosides.

Cladribine, 2-chloro-2'-deoxyadenosine, is a highly efficacious, clinically used nucleoside for the treatment of hairy cell leukemia. It is also being evaluated against other lymphoid malignancies and has been a molecule of interest for well over half a century. In continuation of our interest in the amide bond-activation in purine nucleosides via the use of (benzotriazol-1yl-oxy)tris(dimethylamino)phosphonium hexafluorophosphate, we have evaluated the use of O6-(benzotriazol-1-yl)-2'-deoxyguanosine as a potential precursor to cladribine and its analogues. These compounds, after appropriate deprotection, were assessed for their biological activities, and the data are presented herein. Against hairy cell leukemia (HCL), T-cell lymphoma (TCL) and chronic lymphocytic leukemia (CLL), cladribine was the most active against all. The bromo analogue of cladribine showed comparable activity to the ribose analogue of cladribine against HCL, but was more active against TCL and CLL. The bromo ribose analogue of cladribine showed activity, but was the least active among the C6-NH2-containing compounds. Substitution with alkyl groups at the exocyclic amino group appears detrimental to activity, and only the C6 piperidinyl cladribine analogue demonstrated any activity. Against adenocarcinoma MDA-MB-231 cells, cladribine and its ribose analogue were most active.

Downregulation of deoxycytidine kinase in cytarabine-resistant mantle cell lymphoma cells confers cross-resistance to nucleoside analogs gemcitabine, fludarabine and cladribine, but not to other classes of anti-lymphoma agents.

BACKGROUND: Mantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin lymphoma associated with poor prognosis. Implementation of high-dose cytarabine (araC) into induction therapy became standard-of-care for all newly diagnosed younger MCL patients. However, many patients relapse even after araC-based regimen. Molecular mechanisms responsible for araC resistance in MCL are unknown and optimal treatment strategy for relapsed/refractory MCL patients remains elusive. METHODS: Five araC-resistant (R) clones were derived by long-term culture of five MCL cell lines (CTRL) with increasing doses of araC up to 50 microM. Illumina BeadChip and 2-DE proteomic analysis were used to identify gene and protein expression changes associated with araC resistance in MCL. In vitro cytotoxicity assays and experimental therapy of MCL xenografts in immunodeficient mice were used to analyze their relative responsiveness to a set of clinically used anti-MCL drugs. Primary MCL samples were obtained from patients at diagnosis and after failure of araC-based therapies. RESULTS: Marked downregulation of deoxycytidine-kinase (DCK) mRNA and protein expression was identified as the single most important molecular event associated with araC-resistance in all tested MCL cell lines and in 50% primary MCL samples. All R clones were highly (20-1000x) cross-resistant to all tested nucleoside analogs including gemcitabine, fludarabine and cladribine. In vitro sensitivity of R clones to other classes of clinically used anti-MCL agents including genotoxic drugs (cisplatin, doxorubicin, bendamustine) and targeted agents (bortezomib, temsirolimus, rituximab) remained unaffected, or was even increased (ibrutinib). Experimental therapy of immunodeficient mice confirmed the anticipated loss of anti-tumor activity (as determined by overall survival) of the nucleoside analogs gemcitabine and fludarabine in mice transplanted with R clone compared to mice transplanted with CTRL cells, while the anti-tumor activity of cisplatin, temsirolimus, bortezomib, bendamustine, cyclophosphamide and rituximab remained comparable between the two cohorts. CONCLUSIONS: Acquired resistance of MCL cells to araC is associated with downregulation of DCK, enzyme of the nucleotide salvage pathway responsible for the first phosphorylation (=activation) of most nucleoside analogs used in anti-cancer therapy. The data suggest that nucleoside analogs should not be used in the therapy of MCL patients, who relapse after failure of araC-based therapies.

Intrinsic apoptosis pathway in fallopian tube epithelial cells induced by cladribine.

Cladribine is a purine nucleoside analog which initiates the apoptotic mechanism within cells. Moreover, the available data confirms that cladribine, with the participation of the p53 protein, as well as the proapoptotic proteins from the Bcl-2 family, also induces the activation of the intrinsic apoptosis pathway. However, while there has been a lot of research devoted to the effect of cladribine on lymphatic system cells, little is known about the impact of cladribine on the reproductive system. The aim of our study was to evaluate apoptosis in oviduct epithelial cells sourced from 15 different female rats. In so doing, the sections were stained with caspases 3, 9, and 8. Results suggest that cladribine also induces apoptosis in the oviduct epithelial cells by way of the intrinsic pathway. Indeed, the discontinuing of the administration of cladribine leads to a reduction in the amount of apoptotic cells in the oviduct epithelium.

Magnetic Resonance Imaging Evidence Supporting the Efficacy of Cladribine Tablets in the Treatment of Relapsing-Remitting Multiple Sclerosis.

Numerous therapies are currently available to modify the disease course of multiple sclerosis (MS). Magnetic resonance imaging (MRI) plays a pivotal role in assessing treatment response by providing insights into disease activity and clinical progression. Integrating MRI findings with clinical and laboratory data enables a comprehensive assessment of the disease course. Among available MS treatments, cladribine is emerging as a promising option due to its role as a selective immune reconstitution therapy, with a notable impact on B cells and a lesser effect on T cells. This work emphasizes the assessment of MRI's contribution to MS treatment, particularly focusing on the influence of cladribine tablets on imaging outcomes, encompassing data from pivotal and real-world studies. The evidence highlights that cladribine, compared with placebo, not only exhibits a reduction in inflammatory imaging markers, such as T1-Gd+, T2 and combined unique active (CUA) lesions, but also mitigates the effect on brain volume loss, particularly within grey matter. Importantly, cladribine reveals early action by reducing CUA lesions within the first months of treatment, regardless of a patient's initial conditions. The selective mechanism of action, and sustained efficacy beyond year 2, combined with its early onset of action, collectively position cladribine tablets as a pivotal component in the therapeutic paradigm for MS. Overall, MRI, along with clinical measures, has played a substantial role in showcasing the effectiveness of cladribine in addressing both the inflammatory and neurodegenerative aspects of MS.

ABT199/venetoclax synergism with thiotepa enhances the cytotoxicity of fludarabine, cladribine and busulfan in AML cells.

ABT199/venetoclax, an inhibitor of the pro-survival BCL-2 protein, has improved AML treatment. Its efficacy in hematopoietic stem cell transplantation (HSCT), when combined with other chemotherapeutic drugs, has not been thoroughly investigated. The present study demonstrates the synergistic cytotoxicity of ABT199/venetoclax with the DNA alkylator thiotepa (Thio) in AML cells. Cleavage of Caspase 3, PARP1 and HSP90, as well as increased Annexin V positivity, suggest potent activation of apoptosis by this two-drug combination; increased levels of γ-H2AX, P-CHK1 (S317), P-CHK2 (S19) and P-SMC1 (S957) indicate an enhanced DNA damage response. Likewise, the increased level of P-SAPK/JNK (T183/Y185) and decreased P-PI3Kp85 (Y458) suggest enhanced activation of stress signaling pathways. These molecular readouts were synergistically enhanced when ABT199/venetoclax and Thio were combined with fludarabine, cladribine and busulfan. The five-drug combination decreased the levels of BCL-2, BCL-xL and MCL-1, suggesting its potential clinical relevance in overcoming ABT199/venetoclax resistance. Moreover, this combination is active against P53-negative and FLT3-ITD-positive cell lines. Enhanced activation of apoptosis was observed in leukemia patient-derived cell samples exposed to the five-drug combination, suggesting a clinical relevance. The results provide a rationale for clinical trials using these two- and five-drug combinations as part of a conditioning regimen for AML patients undergoing HSCT.