RESUMO
INTRODUCTION: M8891 is a selective and reversible inhibitor of methionine aminopeptidase 2 (MetAP2). We describe translational research to define the target pharmacokinetics (PK) of M8891 and associated pharmacodynamic (PD) levels, which were used to support efficacious dose selection in humans. METHODS: In vitro and in vivo PK characteristics were investigated in animal species, and data integrated using in vitro-in vivo correlation and allometric methods to predict the clearance, volume of distribution, and absorption parameters of M8891 in humans. In parallel, inhibition of MetAP2 activity by M8891 was studied in renal cancer xenografts in mice by measuring accumulation of Met-EF1α, a substrate of MetAP2. The corresponding PD effect was described by a turnover and effect compartment model. This model was used to simulate PD at the M8891 dose showing in vivo efficacy, i.e. significant tumor growth inhibition. Simulations of M8891 PK and associated PD in humans were conducted by integrating predicted human PK parameters into the preclinical PK/PD model. RESULTS: The target minimum PD level associated with efficacy was determined to be 125 µg Met-EF1α per mg protein. Integrating predicted human PK parameters into the preclinical PK/PD model defined a minimal M8891 concentration at steady-state (Ctrough) of 1500 ng/mL (3.9 µM) in humans as being required to produce the corresponding minimum target Met-EF1a level (125 µg per mg protein). CONCLUSION: The defined target PK and PD levels supported the design of the clinical Phase Ia dose escalation study of M8891 (NCT03138538) and selection of the recommended Phase II dose.
Assuntos
Metaloendopeptidases , Modelos Biológicos , Humanos , Camundongos , Animais , Inibidores da Angiogênese , Inibidores EnzimáticosRESUMO
BACKGROUND: To increase the chances of finding efficacious anticancer drugs, improve development times and reduce costs, it is of interest to rank test compounds based on their potential for human use as early as possible in the drug development process. In this paper, we present a method for ranking radiosensitizers using preclinical data. METHODS: We used data from three xenograft mice studies to calibrate a model that accounts for radiation treatment combined with radiosensitizers. A nonlinear mixed effects approach was utilized where between-subject variability and inter-study variability were considered. Using the calibrated model, we ranked three different Ataxia telangiectasia-mutated inhibitors in terms of anticancer activity. The ranking was based on the Tumor Static Exposure (TSE) concept and primarily illustrated through TSE-curves. RESULTS: The model described data well and the predicted number of eradicated tumors was in good agreement with experimental data. The efficacy of the radiosensitizers was evaluated for the median individual and the 95% population percentile. Simulations predicted that a total dose of 220 Gy (5 radiation sessions a week for 6 weeks) was required for 95% of tumors to be eradicated when radiation was given alone. When radiation was combined with doses that achieved at least 8 [Formula: see text] of each radiosensitizer in mouse blood, it was predicted that the radiation dose could be decreased to 50, 65, and 100 Gy, respectively, while maintaining 95% eradication. CONCLUSIONS: A simulation-based method for calculating TSE-curves was developed, which provides more accurate predictions of tumor eradication than earlier, analytically derived, TSE-curves. The tool we present can potentially be used for radiosensitizer selection before proceeding to subsequent phases of the drug discovery and development process.
Assuntos
Antineoplásicos , Neoplasias , Radiossensibilizantes , Humanos , Animais , Camundongos , Radiossensibilizantes/farmacologia , Radiossensibilizantes/uso terapêutico , Neoplasias/tratamento farmacológico , Neoplasias/radioterapia , Antineoplásicos/uso terapêutico , Terapia CombinadaRESUMO
M3258 is an orally bioavailable, potent, selective, reversible inhibitor of the large multifunctional peptidase 7 (LMP7, ß5i, PSMB8) proteolytic subunit of the immunoproteasome, a component of the cellular protein degradation machinery, highly expressed in malignant hematopoietic cells including multiple myeloma. Here we describe the fit-for-purpose pharmacokinetic (PK)/pharmacodynamic (PD)/efficacy modeling of M3258 based on preclinical data from several species. The inhibition of LMP7 activity (PD) and tumor growth (efficacy) were tested in human multiple myeloma xenografts in mice. PK and efficacy data were correlated yielding a free M3258 concentration of 45 nM for half-maximal tumor growth inhibition (KC50). As M3258 only weakly inhibits LMP7 in mouse cells, both in vitro and in vivo bridging studies were performed in rats, monkeys, and dogs for translational modeling. These data indicated that the PD response in human xenograft models was closely reflected in dog PBMCs. A PK/PD model was established, predicting a free IC50 value of 9 nM for M3258 in dogs in vivo, in close agreement with in vitro measurements. In parallel, the human PK parameters of M3258 were predicted by various approaches including in vitro extrapolation and allometric scaling. Using PK/PD/efficacy simulations, the efficacious dose range and corresponding PD response in human were predicted. Taken together, these efforts supported the design of a phase Ia study of M3258 in multiple myeloma patients (NCT04075721). At the lowest tested dose level, the predicted exposure matched well with the observed exposure while the duration of LMP7 inhibition was underpredicted by the model. SIGNIFICANCE STATEMENT: M3258 is a novel inhibitor of the immunoproteasome subunit LMP7. The human PK and human efficacious dose range of M3258 were predicted using in vitro-in vivo extrapolation and allometric scaling methods together with a fit-for-purpose PK/PD and efficacy model based on data from several species. A comparison with data from the Phase Ia clinical study showed that the human PK was accurately predicted, while the extent and duration of PD response were more pronounced than estimated.
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Mieloma Múltiplo , Humanos , Ratos , Camundongos , Animais , Cães , Mieloma Múltiplo/tratamento farmacológico , Modelos BiológicosRESUMO
Pan-proteasome inhibitors (pPIs) significantly improve outcomes in patients with multiple myeloma; however, their indiscriminate inhibition of multiple proteasome and immunoproteasome subunits causes diverse toxicities, including thrombocytopenia. We investigated the mechanisms underlying the platelet depletion induced by the pPIs bortezomib, carfilzomib, and ixazomib. An established thrombocytopenia model was adapted for each compound (bortezomib, ixazomib, and carfilzomib) to compare the following two pharmacodynamic mechanisms: a reversible inhibition of new progenitor cell formation (the myelosuppression model) and a reversible effect on the function of megakaryocytes to bud new platelets (platelet formation model). Bortezomib, ixazomib, and carfilzomib plasma concentration profiles and platelet counts were extracted from the literature. Pharmacokinetic (PK) and thrombocytopenia models were developed to predict the PK of these drugs and to describe their effects on proliferating cells and platelet budding. The PK models reproduced the exposure of the three compounds at steady state well compared with those reported in the literature. Both the platelet formation and myelosuppression models seemed able to describe the platelet depletion caused by bortezomib, ixazomib, and carfilzomib. Estimated structural parameters in the myelosuppression model were in the range of the values reported in the literature, whereas the mean transit time estimated with the platelet formation model was 3-fold to 10-fold higher than the highest reported value. The model of drug-induced myelosuppression yielded estimates of structural parameters in the range of those previously reported. The platelet formation model captured the temporal variation reported in clinical studies.
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Antineoplásicos , Trombocitopenia , Antineoplásicos/farmacologia , Plaquetas , Bortezomib , Humanos , Inibidores de Proteassoma/efeitos adversos , Inibidores da Bomba de Prótons , Trombocitopenia/induzido quimicamenteRESUMO
A central question in drug discovery is how to select drug candidates from a large number of available compounds. This analysis presents a model-based approach for comparing and ranking combinations of radiation and radiosensitizers. The approach is quantitative and based on the previously-derived Tumor Static Exposure (TSE) concept. Combinations of radiation and radiosensitizers are evaluated based on their ability to induce tumor regression relative to toxicity and other potential costs. The approach is presented in the form of a case study where the objective is to find the most promising candidate out of three radiosensitizing agents. Data from a xenograft study is described using a nonlinear mixed-effects modeling approach and a previously-published tumor model for radiation and radiosensitizing agents. First, the most promising candidate is chosen under the assumption that all compounds are equally toxic. The impact of toxicity in compound selection is then illustrated by assuming that one compound is more toxic than the others, leading to a different choice of candidate.
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Neoplasias , Radiossensibilizantes , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/radioterapia , Radiossensibilizantes/farmacologia , Radiossensibilizantes/uso terapêuticoRESUMO
Tepotinib is a highly selective and potent MET inhibitor in development for the treatment of patients with solid tumors. Given the favorable tolerability and safety profiles up to the maximum tested dose in the first-in-human (FIH) trial, an efficacy-driven translational modeling approach was proposed to establish the recommended phase II dose (RP2D). To study the in vivo pharmacokinetics (PKs)/target inhibition/tumor growth inhibition relationship, a subcutaneous KP-4 pancreatic cell-line xenograft model in mice with sensitivity to MET pathway inhibition was selected as a surrogate tumor model. Further clinical PK and target inhibition data (derived from predose and postdose paired tumor biopsies) from a FIH study were integrated with the longitudinal PKs and target inhibition profiles from the mouse xenograft study to establish a translational PK/pharmacodynamic (PD) model. Preclinical data showed that tumor regression with tepotinib treatment in KP-4 xenograft tumors corresponded to 95% target inhibition. We therefore concluded that a PD criterion of sustained, near-to-complete (>95%) phospho-MET inhibition in tumors should be targeted for tepotinib to be effective. Simulations of dose-dependent target inhibition profiles in human tumors that exceeded the PD threshold in more than 90% of patients established an RP2D of tepotinib 500 mg once daily. This translational mathematical modeling approach supports an efficacy-driven rationale for tepotinib phase II dose selection of 500 mg once daily. Tepotinib at this dose has obtained regulatory approval for the treatment of patients with non-small cell lung cancer harboring MET exon 14 skipping.
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Avaliação Pré-Clínica de Medicamentos , Modelos Teóricos , Piperidinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Piridazinas/farmacologia , Pirimidinas/farmacologia , Administração Oral , Animais , Ensaios Clínicos Fase II como Assunto , Relação Dose-Resposta a Droga , Humanos , Camundongos , Piperidinas/administração & dosagem , Piperidinas/farmacocinética , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/farmacocinética , Piridazinas/administração & dosagem , Piridazinas/farmacocinética , Pirimidinas/administração & dosagem , Pirimidinas/farmacocinética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: This open-label, phase 1 trial (NCT02316197) aimed to determine the maximum-tolerated dose (MTD) and/or recommended phase 2 dose (RP2D) of peposertib (formerly M3814), a DNA-dependent protein kinase (DNA-PK) inhibitor in patients with advanced solid tumours. Secondary/exploratory objectives included safety/tolerability, pharmacokinetic/pharmacodynamic profiles and clinical activity. METHODS: Adult patients with advanced solid tumours received peposertib 100-200 mg once daily or 150-400 mg twice daily (BID) in 21-day cycles. RESULTS: Thirty-one patients were included (median age 66 years, 61% male). One dose-limiting toxicity, consisting of mainly gastrointestinal, non-serious adverse events (AEs) and long recovery duration, was reported at 300 mg BID. The most common peposertib-related AEs were nausea, vomiting, fatigue and pyrexia. The most common peposertib-related Grade 3 AEs were maculopapular rash and nausea. Peposertib was quickly absorbed systemically (median Tmax 1.1-2.5 h). The p-DNA-PK/t-DNA-PK ratio decreased consistently in peripheral blood mononuclear cells 3-6 h after doses ≥100 mg. The best overall response was stable disease (12 patients), lasting for ≥12 weeks in seven patients. CONCLUSIONS: Peposertib was well-tolerated and demonstrated modest efficacy in unselected tumours. The MTD was not reached; the RP2D was declared as 400 mg BID. Further studies, mainly with peposertib/chemo-radiation, are ongoing. CLINICAL TRIAL REGISTRATION: NCT02316197.
Assuntos
Proteína Quinase Ativada por DNA/antagonistas & inibidores , Neoplasias/tratamento farmacológico , Piridazinas/administração & dosagem , Piridazinas/efeitos adversos , Quinazolinas/administração & dosagem , Quinazolinas/efeitos adversos , Adulto , Idoso , Proteína Quinase Ativada por DNA/metabolismo , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/metabolismo , Neoplasias/patologia , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/efeitos adversos , Inibidores de Proteínas Quinases/farmacocinética , Piridazinas/farmacocinética , Quinazolinas/farmacocinéticaRESUMO
Bintrafusp alfa, a first-in-class bifunctional fusion protein composed of the extracellular domain of the TGF-ßRII receptor (TGF-ß "trap") fused to a human IgG1-blocking PD-L1, showed a manageable safety profile and clinical activity in phase I studies in patients with heavily pretreated advanced solid tumors. The recommended phase 2 dose (RP2D) was selected based on integration of modeling, simulations, and all available data. A 1,200-mg every 2 weeks (q2w) dose was predicted to maintain serum trough concentration (Ctrough ) that inhibits all targets of bintrafusp alfa in circulation in > 95% of patients, and a 2,400-mg every 3 weeks (q3w) dose was predicted to have similar Ctrough . A trend toward an association between exposure and efficacy variables and a relatively stronger inverse association between clearance and efficacy variables were observed. Exposure was either weakly or not correlated with probability of adverse events. The selected intravenous RP2D of bintrafusp alfa is 1,200 mg q2w or 2,400 mg q3w.
Assuntos
Antineoplásicos Imunológicos/administração & dosagem , Antígeno B7-H1/antagonistas & inibidores , Cálculos da Dosagem de Medicamento , Inibidores de Checkpoint Imunológico/administração & dosagem , Neoplasias/tratamento farmacológico , Fator de Crescimento Transformador beta/antagonistas & inibidores , Administração Intravenosa , Animais , Antineoplásicos Imunológicos/efeitos adversos , Antineoplásicos Imunológicos/farmacocinética , Antígeno B7-H1/metabolismo , Ensaios Clínicos Fase I como Assunto , Ensaios Clínicos Fase II como Assunto , Simulação por Computador , Modelos Animais de Doenças , Esquema de Medicação , Humanos , Inibidores de Checkpoint Imunológico/efeitos adversos , Inibidores de Checkpoint Imunológico/farmacocinética , Camundongos , Modelos Teóricos , Terapia de Alvo Molecular , Neoplasias/imunologia , Neoplasias/metabolismo , Neoplasias/patologia , Projetos de Pesquisa , Fator de Crescimento Transformador beta/metabolismoRESUMO
PURPOSE: Tepotinib is an oral, potent, highly selective MET inhibitor. This first-in-man phase I trial investigated the MTD of tepotinib to determine the recommended phase II dose (RP2D). PATIENTS AND METHODS: Patients received tepotinib orally according to one of three dose escalation regimens (R) on a 21-day cycle: R1, 30-400 mg once daily for 14 days; R2, 30-315 mg once daily 3 times/week; or R3, 300-1,400 mg once daily. After two cycles, treatment could continue in patients with stable disease until disease progression or unacceptable toxicity. The primary endpoint was incidence of dose-limiting toxicity (DLT) and treatment-emergent adverse events (TEAE). Secondary endpoints included safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor effects. RESULTS: One hundred and forty-nine patients received tepotinib (R1: n = 42; R2: n = 45; R3: n = 62). Although six patients reported DLTs [one patient in R1 (115 mg), three patients in R2 (60, 100, 130 mg), two patients in R3 (1,000, 1,400 mg)], the MTD was not reached at the highest tested dose of 1,400 mg daily. The RP2D of tepotinib was established as 500 mg once daily, supported by translational modeling data as sufficient to achieve ≥95% MET inhibition in ≥90% of patients. Treatment-related TEAEs were mostly grade 1 or 2 fatigue, peripheral edema, decreased appetite, nausea, vomiting, and lipase increase. The best overall response in R3 was partial response in two patients, both with MET overexpression. CONCLUSIONS: Tepotinib was well tolerated with clinical activity in MET-dysregulated tumors. The RP2D of tepotinib was established as 500 mg once daily. MET abnormalities can drive tumorigenesis. This first-in-man trial demonstrated that the potent, highly selective MET inhibitor tepotinib can reduce or stabilize tumor burden and is well tolerated at doses up to 1,400 mg once daily. An RP2D of 500 mg once daily, as determined from translational modeling and simulation integrating human population pharmacokinetic and pharmacodynamic data in tumor biopsies, is being used in ongoing clinical trials.
Assuntos
Neoplasias/tratamento farmacológico , Piperidinas/farmacocinética , Piperidinas/uso terapêutico , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Piridazinas/farmacocinética , Piridazinas/uso terapêutico , Pirimidinas/farmacocinética , Pirimidinas/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Dose Máxima Tolerável , Pessoa de Meia-Idade , Náusea/induzido quimicamente , Neoplasias/patologia , Segurança do Paciente , Inibidores de Proteínas Quinases/farmacocinética , Inibidores de Proteínas Quinases/uso terapêutico , Distribuição Tecidual , Resultado do Tratamento , Vômito/induzido quimicamente , Adulto JovemRESUMO
PURPOSE: Radiation therapy, whether given alone or in combination with chemical agents, is one of the cornerstones of oncology. We develop a quantitative model that describes tumor growth during and after treatment with radiation and radiosensitizing agents. The model also describes long-term treatment effects including tumor regrowth and eradication. METHODS: We challenge the model with data from a xenograft study using a clinically relevant administration schedule and use a mixed-effects approach for model-fitting. We use the calibrated model to predict exposure combinations that result in tumor eradication using Tumor Static Exposure (TSE). RESULTS: The model is able to adequately describe data from all treatment groups, with the parameter estimates taking biologically reasonable values. Using TSE, we predict the total radiation dose necessary for tumor eradication to be 110 Gy, which is reduced to 80 or 30 Gy with co-administration of 25 or 100 mg kg-1 of a radiosensitizer. TSE is also explored via a heat map of different growth and shrinkage rates. Finally, we discuss the translational potential of the model and TSE concept to humans. CONCLUSIONS: The new model is capable of describing different tumor dynamics including tumor eradication and tumor regrowth with different rates, and can be calibrated using data from standard xenograft experiments. TSE and related concepts can be used to predict tumor shrinkage and eradication, and have the potential to guide new experiments and support translations from animals to humans.
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Modelos Biológicos , Neoplasias/radioterapia , Radiossensibilizantes/administração & dosagem , Animais , Relação Dose-Resposta a Droga , Feminino , Humanos , Camundongos , Camundongos Nus , Dosagem Radioterapêutica , Especificidade da Espécie , Resultado do Tratamento , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Radiotherapy is one of the major therapy forms in oncology, and combination therapies involving radiation and chemical compounds can yield highly effective tumor eradication. In this paper, we develop a tumor growth inhibition model for combination therapy with radiation and radiosensitizing agents. Moreover, we extend previous analyses of drug combinations by introducing the tumor static exposure (TSE) curve. The TSE curve for radiation and radiosensitizer visualizes exposure combinations sufficient for tumor regression. The model and TSE analysis are then tested on xenograft data. The calibrated model indicates that the highest dose of combination therapy increases the time until tumor regrowth 10-fold. The TSE curve shows that with an average radiosensitizer concentration of 1.0 µg/mL the radiation dose can be decreased from 2.2 Gy to 0.7 Gy. Finally, we successfully predict the effect of a clinically relevant treatment schedule, which contributes to validating both the model and the TSE concept.
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Modelos Biológicos , Neoplasias/radioterapia , Radiossensibilizantes/uso terapêutico , Animais , Terapia Combinada , Humanos , Neoplasias/tratamento farmacológico , Valor Preditivo dos Testes , Radiossensibilizantes/administração & dosagem , Radioterapia/métodos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Combination therapies are widely accepted as a cornerstone for treatment of different cancer types. A tumor growth inhibition (TGI) model is developed for combinations of cetuximab and cisplatin obtained from xenograft mice. Unlike traditional TGI models, both natural cell growth and cell death are considered explicitly. The growth rate was estimated to 0.006 h-1 and the natural cell death to 0.0039 h-1 resulting in a tumor doubling time of 14 days. The tumor static concentrations (TSC) are predicted for each individual compound. When the compounds are given as single-agents, the required concentrations were computed to be 506 µg · mL-1 and 56 ng · mL-1 for cetuximab and cisplatin, respectively. A TSC curve is constructed for different combinations of the two drugs, which separates concentration combinations into regions of tumor shrinkage and tumor growth. The more concave the TSC curve is, the lower is the total exposure to test compounds necessary to achieve tumor regression. The TSC curve for cetuximab and cisplatin showed weak concavity. TSC values and TSC curves were estimated that predict tumor regression for 95% of the population by taking between-subject variability into account. The TSC concept is further discussed for different concentration-effect relationships and for combinations of three or more compounds.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Modelos Biológicos , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Carcinoma Pulmonar de Células não Pequenas/patologia , Cetuximab/administração & dosagem , Cisplatino/administração & dosagem , Relação Dose-Resposta a Droga , Feminino , Humanos , Neoplasias Pulmonares/patologia , Camundongos , Camundongos Nus , Ensaios Antitumorais Modelo de Xenoenxerto/métodosRESUMO
Mediator-associated kinases CDK8/19 are context-dependent drivers or suppressors of tumorigenesis. Their inhibition is predicted to have pleiotropic effects, but it is unclear whether this will impact on the clinical utility of CDK8/19 inhibitors. We discovered two series of potent chemical probes with high selectivity for CDK8/19. Despite pharmacodynamic evidence for robust on-target activity, the compounds exhibited modest, though significant, efficacy against human tumor lines and patient-derived xenografts. Altered gene expression was consistent with CDK8/19 inhibition, including profiles associated with super-enhancers, immune and inflammatory responses and stem cell function. In a mouse model expressing oncogenic beta-catenin, treatment shifted cells within hyperplastic intestinal crypts from a stem cell to a transit amplifying phenotype. In two species, neither probe was tolerated at therapeutically-relevant exposures. The complex nature of the toxicity observed with two structurally-differentiated chemical series is consistent with on-target effects posing significant challenges to the clinical development of CDK8/19 inhibitors.
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Anti-Inflamatórios/administração & dosagem , Antineoplásicos/administração & dosagem , Quinase 8 Dependente de Ciclina/antagonistas & inibidores , Quinases Ciclina-Dependentes/antagonistas & inibidores , Complexo Mediador/antagonistas & inibidores , Inibidores de Proteínas Quinases/administração & dosagem , Animais , Anti-Inflamatórios/efeitos adversos , Anti-Inflamatórios/toxicidade , Antineoplásicos/efeitos adversos , Antineoplásicos/toxicidade , Modelos Animais de Doenças , Xenoenxertos , Humanos , Hiperplasia/tratamento farmacológico , Camundongos , Neoplasias/tratamento farmacológico , Inibidores de Proteínas Quinases/efeitos adversos , Inibidores de Proteínas Quinases/toxicidade , Resultado do TratamentoRESUMO
We recently showed that targeting bSMase (bacterial sphingomyelinase) specifically to mitochondria caused accumulation of ceramide in mitochondria, and induced cytochrome c release and cell death [Birbes, El Bawab, Hannun and Obeid (2001) FASEB J., 15, 2669-2679]. In the present study, we investigated the role of this mitochondrial pool of ceramide in response to a receptor-mediated event, namely TNFalpha (tumour necrosis factor alpha), and the involvement of this mitochondrial pool of ceramide in Bax translocation to mitochondria, an event that precedes cytochrome c release. Treatment of MCF7 cells with TNFalpha caused an increase in ceramide levels in the mitochondrial fraction which accompanied Bax translocation to mitochondria. Targeting bSMase to mitochondria specifically resulted in Bax translocation to mitochondria, suggesting that the mitochondrial ceramide pool is involved in Bax translocation. Moreover, in a reconstituted cell-free system, treatment of isolated mitochondria with bSMase enhanced Bax association with mitochondrial membranes. Collectively, these results suggest that the generation of ceramide in mitochondria in response to TNFalpha is sufficient to induce Bax translocation to mitochondria and subsequent cytochrome c release and cell death.