Dual targeting of MCL1 and NOXA as effective strategy for treatment of mantle cell lymphoma

Imbalances in the composition of BCL2 family proteins contribute to tumourigenesis and therapy resistance of mantle cell lymphoma (MCL), making these proteins attractive therapy targets. We studied the efficiency of dual targeting the NOXA/MCL1 axis by combining fatty acid synthase inhibitors (NOXA stabilization) with the CDK inhibitor Dinaciclib (MCL1 reduction). This combination synergistically induced apoptosis in cell lines and primary MCL cells and led to almost complete inhibition of tumour progression in a mouse model. Apoptosis was NOXA‐dependent and correlated with the NOXA/MCL1 ratio, highlighting the importance of the NOXA/MCL1 balance for effective cell death induction in MCL.     

Abnormal expression of apoptosis-related genes in haematological malignancies: overexpression of MYC is poor prognostic sign in mantle cell lymphoma

The expression of apoptosis-related genes BCL2, BAX, BCL2L1, BCL2A1, MCL1, DAPK1 and MYC was studied by quantitative real-time polymerase chain reaction on total RNA samples from patients with acute lymphoblastic leukaemia (ALL, n = 16), acute myeloid leukaemia (AML, n = 27), chronic myeloid leukaemia (CML, n = 12), mantle cell lymphoma (MCL, n = 19) and chronic lymphoid leukaemia (CLL, n = 32). BCL2, BAX, BCL2A1, MCL1, DAPK1 and MYC were overexpressed in all patient groups. BCL2L1 was underexpressed in CLL and CML, but not in AML, ALL and MCL. MCL1 levels were significantly higher in CD13 and CD33-positive ALL, and in CD56-positive AML samples. BCL2, BCL2L1, BCL2A1 and MCL1 were overexpressed and DAPK1 was underexpressed in CLL samples with a 11q23 deletion. MYC overexpression was significantly associated with shorter overall survival in MCL (P < 0.01). AML patients with a normal karyotype showed a higher frequency of BCL2A1 overexpression (P < 0.001) than those with an abnormal karyotype.     

AXL/MERTK inhibitor ONO-7475 potently synergizes with venetoclax and overcomes venetoclax resistance to kill F LT 3-ITD acute myeloid leukemia

FMS-like Tyrosine Kinase 3 (FLT3) mutation is associated with poor survival in acute myeloid leukemia (AML). The specific Anexelekto/MER Tyrosine Kinase (AXL) inhibitor, ONO-7475, kills FLT3-mutant AML cells with targets including Extracellular-signal Regulated Kinase (ERK) and Myeloid Cell Leukemia 1 (MCL1). ERK and MCL1 are known resistance factors for Venetoclax (ABT-199), a popular drug for AML therapy, prompting the investigation of the efficacy of ONO-7475 in combination with ABT-199 in vitro and in vivo. ONO-7475 synergizes with ABT-199 to potently kill FLT3-mutant acute myeloid leukemia cell lines and primary cells. ONO-7475 is effective against ABT-199-resistant cells including cells that overexpress MCL1. Proteomic analyses revealed that ABT-199-resistant cells expressed elevated levels of pro-growth and anti-apoptotic proteins compared to parental cells, and that ONO-7475 reduced the expression of these proteins in both the parental and ABT-199-resistant cells. ONO-7475 treatment significantly extended survival as a single in vivo agent using acute myeloid leukemia cell lines and PDX models. Compared to ONO-7474 monotherapy, the combination of ONO-7475/ABT-199 was even more potent in reducing leukemic burden and prolonging the survival of mice in both model systems. These results suggest that the ONO-7475/ABT-199 combination may be effective for AML therapy.     

维奈克拉联合阿扎胞苷与地西他滨联合预激方案治疗老年复发急性髓系白血病的疗效及安全性比较的初步观察

目的比较维奈克拉(venetoclax, VEN)联合阿扎胞苷(azacitidine, AZA)方案与地西他滨(decitabine/dacogen, DAC)联合预激方案治疗老年复发急性髓系白血病(acute myeloid leukemia, AML)的疗效及安全性。方法回顾性分析2018年1月至 2020年8月苏州大学附属第一医院血液科收治的45例老年复发AML患者的临床资料, 男性31例、女性14例, 年龄60～80岁, 中位年龄66岁, 其中18例采用VEN+AZA方案治疗, 27例采用DAC+预激方案治疗。比较两组患者的完全缓解率(complete remission, CR)、部分缓解率(partial remission, PR)、总有效率(overall response rate, ORR), 不良反应发生率以及总体生存(overall survival, OS)。结果 VEN+AZA组ORR为 14/18, 其中CR 11例、PR 3例;DAC+预激组ORR为37.0%(10/27), 其中CR 8例、PR 2例, 两组患者疗效差异有统计学意义(P=0.007)...     

A venetoclax and azacitidine bridge-to-transplant strategy for NPM1-mutated acute myeloid leukaemia in molecular failure

NPM1-mutated acute myeloid leukaemia (NPM1^mut AML) represents a mostly favourable/intermediate risk disease that benefits from allogeneic haematopoietic stem cell transplantation (HSCT) in case of measurable residual disease (MRD) relapse or persistence after induction chemotherapy. Although the negative prognostic role of pre-HSCT MRD is established, no recommendations are available for the management of peri-transplant molecular failure (MF). Based on the efficacy data of venetoclax (VEN)-based treatment in NPM1^mut AML older patients, we retrospectively analysed the off-label combination of VEN plus azacitidine (AZA) as bridge-to-transplant strategy in 11 NPM1^mut MRD-positive fit AML patients. Patients were in MRD-positive complete remission (CR_MRDpos) at the time of treatment: nine in molecular relapse and two in molecular persistence. After a median number of two cycles (range 1–4) of VEN–AZA, 9/11 (81.8%) achieved CR_MRD-negative (CR_MRDneg). All 11 patients proceeded to HSCT. With a median follow-up from treatment start of 26 months, and a median post-HSCT follow-up of 19 months, 10/11 patients are alive (1 died from non-relapse mortality), and 9/10 patients are in MRD_neg status. This patient series highlights the efficacy and safety of VEN–AZA to prevent overt relapse, achieve deep responses and preserve patient fitness before HSCT, in patients with NPM1^mut AML in MF.     

MCL1, a gene expressed in programmed myeloid cell differentiation, has sequence similarity to BCL2.

During their lifespan, immature cells normally pass through sequential transitions to a differentiated state and eventually undergo cell death. This progression is aberrant in cancer, although the transition to differentiation can be reestablished in inducible leukemia cell lines. This report describes a gene, MCL1, that we isolated from the ML-1 human myeloid leukemia cell line during phorbol ester-induced differentiation along the monocyte/macrophage pathway. Our results demonstrate that expression of MCL1 increases early in the induction, or "programming," of differentiation in ML-1 (at 1-3 hr), before the appearance of differentiation markers and mature morphology (at 1-3 days). They further show that MCL1 has sequence similarity to BCL2, a gene involved in normal lymphoid development and in lymphomas with the t(14;18) chromosome translocation. MCL1 and BCL2 do not fall into previously known gene families. BCL2 differs from many oncogenes in that it inhibits programmed cell death, promoting viability rather than proliferation; this parallels the association of MCL1 with the programming of differentiation and concomitant maintenance of viability but not proliferation. Thus, in contrast to proliferation-associated genes, expression of MCL1 and BCL2 relates to the programming of differentiation and cell viability/death. The discovery of MCL1 broadens our perspective on an emerging MCL1/BCL2 gene family and will allow further comparison with oncogene families.     

Azacitidine with or without Entinostat for the treatment of therapy‐related myeloid neoplasm: further results of the E1905 North American Leukemia Intergroup study

Therapy‐related myeloid neoplasms (tMN) are serious late effects of the treatment of cancer with poor response to conventional treatment. Azacitidine (AZA) has been used to treat patients with tMN but current data are retrospective. We present here 47 tMN patients prospectively enrolled as a specific cohort in the E1905 study. The E1905 study was a randomized phase 2 study (NCT00313586) testing 10 d of AZA (50 mg/m²/d) +/? the histone deacetylase inhibitor entinostat (4 mg/m²/d PO day‐3 and day‐10). A total of 47 patients [29 therapy‐related myelosyspastic syndrome (t‐MDS) and 18 therapy‐related acute myeloid leukaemia (t‐AML)] were recruited to the study. 24 patients were treated with AZA monotherapy and 23 with AZA+entinostat. The median number of administered cycles was 4, significantly higher in patients treated with AZA (6 cycles vs. 3 cycles, P = 0·008). Haematological normalization rates were 46% in monotherapy and 17% in the combination arm. Median overall survivals were 13 and 6 months, respectively. The novel 50 * 10 schedule of azacitidine appears effective, with response rates, when given as single agent, comparable to those for patients with de novo MDS/AML treated on the same protocol. However, the combination of AZA and entinostat was associated with increased toxicity and could not be recommended for treatment of tMN.     

Inhibition of casein kinase 2 sensitizes mantle cell lymphoma to venetoclax through MCL-1 downregulation

BCL-2 family proteins are frequently aberrantly expressed in mantle cell lymphoma (MCL). Recently, the BCL-2-specific inhibitor venetoclax has been approved by the US Food and Drug Administration for chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML). In MCL, venetoclax has shown promising efficacy in early clinical trials; however, a significant subset of patients is resistant. By conducting a kinome-centered CRISPR-Cas9 knockout sensitizer screen, we identified casein kinase 2 (CK2) as a major regulator of venetoclax resistance in MCL. Interestingly, CK2 is over-expressed in MCL and high CK2 expression is associated with poor patient survival. Targeting of CK2, either by inducible short hairpin RNA (shRNA)-mediated knockdown of CK2 or by the CK2-inhibitor silmitasertib, did not affect cell viability by itself, but strongly synergized with venetoclax in both MCL cell lines and primary samples, also if combined with ibrutinib. Furthermore, targeting of CK2 reduced MCL-1 levels, which involved impaired MCL-1 translation by inhibition of eIF4F complex assembly, without affecting BCL-2 and BCL-X_L expression. Combined, this results in enhanced BCL-2 dependence and, consequently, venetoclax sensitization. In cocultures, targeting of CK2 overcame stroma-mediated venetoclax resistance of MCL cells. Taken together, our findings indicate that targeting of CK2 sensitizes MCL cells to venetoclax through downregulation of MCL-1. These novel insights provide a strong rationale for combining venetoclax with CK2 inhibition as therapeutic strategy for MCL patients.     

A phase I/II study of the combination of quizartinib with azacitidine or low-dose cytarabine for the treatment of patients with acute myeloid leukemia or myelodysplastic syndrome

The FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutation in acute myeloid leukemia (AML) is associated with poor prognosis. We hypothesized that quizartinib, a selective and potent FLT3 inhibitor, with azacitidine (AZA) or low-dose cytarabine (LDAC) might improve the outcomes in patients with FLT3-ITD-mutated AML. In this open-label phase I/II trial, patients of any age receiving first-salvage treatment for FLT3-ITD AML or age >60 years with untreated myelodysplastic syndrome or AML were treated with quizartinib plus AZA or LDAC. Seventy-three patients were treated (34 frontline, 39 first salvage). With regard to previously untreated patients, the composite response (CRc) rate was 87% (n=13/15: 8 complete responses [CR], 4 CR with incomplete hematologic recovery [CRi], 1 CR without platelet recovery [CRp]) among the patients treated with quizartinib/AZA and 74% (n=14/19: 1 CR, 8 CRi, 5 CRp) among those treated with quizartinib/LDAC. The median overall survival was 19.2 months for the cohort treated with quizartinib/AZA cohort and 8.5 months for the patients treated with quizartinib/LDAC; the corresponding relapse-free survival figures were 10.5 and 6.4 months, respectively. With regard to previously treated patients, the CRc rate was 64% (n=16/25 in the quizartinib/AZA cohort and 29% (n=4/14)) in the quizartinib/LDAC cohort. The median overall survival for patients treated with quizartinib/AZA and quizartinib/LDAC was 12.8 versus 4 months, respectively. QTc prolongation grade 3 occurred in only one patient in each cohort. Quizartinib-based combinations, particularly with AZA, appear effective in both frontline and first salvage therapy for patients with FLT3-ITD-mutated AML and are well tolerated. ClinicalTrials.gov identifier: {"type":"clinical-trial","attrs":{"text":"NCT01892371","term_id":"NCT01892371"}}NCT01892371.     

Targeting anti‐apoptotic BCL2 family proteins in haematological malignancies – from pathogenesis to treatment

The B‐cell lymphoma 2 (BCL 2) family of proteins comprise key regulators of apoptosis and are implicated in the pathogenesis of many malignancies, including lymphomas and leukaemias. Targeting of BCL 2 proteins can be directly toxic to tumour cells or render them more sensitive to chemotherapy. Inhibition of the anti‐apoptotic functions of BCL 2 proteins using structure‐based design to produce specific inhibitors of protein–protein interactions has been achieved for BCL 2, MCL 1 and BCL ‐X_L (also termed BCL 2L1), providing an armamentarium of new targeted therapies called BH 3‐mimetics. The first BCL 2‐specific inhibitor, venetoclax, has shown extraordinary single agent activity in chronic lymphocytic leukaemia (CLL ), with surprisingly little toxicity given the expression of BCL 2 in normal tissues. Despite success in CLL , where sensitivity to BCL 2 inhibition is seen in nearly all cases, key questions have not yet been addressed. For example, responses to venetoclax in other B‐cell and myeloid malignancies are heterogeneous, highlighting the need to identify biomarkers that correlate with response and, secondly, to identify/develop other specific compounds that synergise with BCL 2 inhibition. In this review, we summarise the biology of BCL 2 proteins, the mechanism of action of BH 3‐mimetics and the status of their clinical development in haematological malignancies.     

Targeting MCL-1 dysregulates cell metabolism and leukemia-stroma interactions and re-sensitizes acute myeloid leukemia to BCL-2 inhibition

MCL-1 and BCL-2 are both frequently overexpressed in acute myeloid leukemia (AML) and critical for the survival of AML cells and AML stem cells. MCL-1 is a key factor in venetoclax resistance. Using genetic and pharmacological approaches, we discovered that MCL-1 regulates leukemia cell bioenergetics and carbohydrate metabolisms, including the TCA cycle, glycolysis and pentose phosphate pathway and modulates cell adhesion proteins and leukemia-stromal interactions. Inhibition of MCL-1 sensitizes to BCL-2 inhibition in AML cells and AML stem/progenitor cells, including those with intrinsic and acquired resistance to venetoclax through cooperative release of pro-apoptotic BIM, BAX, and BAK from binding to anti-apoptotic BCL- 2 proteins and inhibition of cell metabolism and key stromal microenvironmental mechanisms. The combined inhibition of MCL-1 by MCL-1 inhibitor AZD5991 or CDK9 inhibitor AZD4573 and BCL-2 by venetoclax greatly extended survival of mice bearing patient-derived xenografts established from an AML patient who acquired resistance to venetoclax/decitabine. These results demonstrate that co-targeting MCL-1 and BCL-2 improves the efficacy of and overcomes pre-existing and acquired resistance to BCL-2 inhibition. Activation of metabolomic pathways and leukemia-stroma interactions are newly discovered functions of MCL-1 in AML, which are independent from canonical regulation of apoptosis by MCL-1. Our data provide new mechanisms of synergy and a rationale for co-targeting MCL-1 and BCL-2 clinically in patients with AML and potentially other cancers.     

AT‐101 downregulates BCL2 and MCL1 and potentiates the cytotoxic effects of lenalidomide and dexamethasone in preclinical models of multiple myeloma and Waldenström macroglobulinaemia

Multiple myeloma, the second most common haematological malignancy in the U.S., is currently incurable. Disruption of the intrinsic apoptotic pathway by BCL2 and MCL1 upregulation is observed in >80% of myeloma cases and is associated with an aggressive clinical course. Remarkably, there is no approved drug with the ability to target BCL2 or MCL1. Thus, we investigated the anti‐tumour effects of a pan‐BCL2 inhibitor, AT‐101, which has high binding specificity for BCL2 and MCL1 in preclinical models of plasma cell cancers (Multiple myeloma and Waldenström macroglobulinaemia). Gene expression and immunoblot analysis of six plasma cell cancer models showed upregulation of BCL2 family members. AT‐101 was able to downregulate BCL2 and MCL1 in all plasma cell cancer models and induced apoptotic cell death in a caspase‐dependent manner by altering mitochondrial membrane permeability. This cytotoxic effect and BCL2 downregulation were further potentiated when AT‐101 was combined with lenalidomide/dexamethasone (LDA). NanoString nCounter mRNA quantification and Ingenuity Pathways Analysis revealed differential changes in the CCNA2, FRZB, FYN, IRF1, PTPN11 genes in LDA‐treated cells. In summary, we describe for the first time the cellular and molecular events associated with the use of AT‐101 in combination with lenalidomide/dexamethasone in preclinical models of plasma cell malignancy.     

Synergistic activity of IDH1 inhibitor BAY1436032 with azacitidine in IDH1 mutant acute myeloid leukemia

Mutant isocitrate dehydrogenase 1 (mIDH1) inhibitors have shown single-agent activity in relapsed/refractory acute myeloid leukemia (AML), even though most patients eventually relapse. We evaluated the efficacy and molecular mechanism of the combination treatment with azacitidine, which is currently the standard of care in older AML patients, and mIDH1 inhibitor BAY1436032. Both compounds were evaluated in vivo as single agents and in combination with sequential (azacitidine, followed by BAY1436032) or simultaneous application in two human IDH1 mutated AML xenograft models. Combination treatment significantly prolonged survival compared to single agent or control treatment (P<0.005). The sequential combination treatment depleted leukemia stem cells by 470-fold. Interestingly, the simultaneous combination treatment depleted leukemia stem cells by 33,150-fold compared to control mice. This strong synergy is mediated through inhibition of MAPK/ERK and Rb/E2F signaling. Our data strongly argues for the concurrent application of mIDH1 inhibitors and azacitidine and predicts improved outcome of this regimen in IDH1 mutated AML patients.     

Is the overall survival for older adults with AML finally improving?

Older adults with acute myeloid leukemia (AML) traditionally have very poor survival outcomes. Those who receive only supportive care have worse overall survival than those who undergo treatment, regardless of treatment type, and improvements in overall survival in the last several decades are largely attributable to the increasing decision to treat rather than offer only supportive care. However, there are a few newer agents that appear promising; these include CPX-351 (a liposomal product with cytarabine and daunorubicin), glasdegib (a selective Hedgehog signaling pathway inhibitor), and venetoclax (potent small molecule inhibitor of BCL2). A systematic review and meta-analysis is being completed to help clinicians optimize standard therapies for older AML patients.     

Acute myeloid/T‐lymphoblastic leukaemia (AMTL): a distinct category of acute leukaemias with common pathogenesis in need of improved therapy

Advances in the classification of acute leukaemias have led to improved outcomes for a substantial fraction of patients. However, chemotherapy resistance remains a major problem for specific subsets of acute leukaemias. Here, we propose that a molecularly distinct subtype of acute leukaemia with shared myeloid and T cell lymphoblastic features, which we term acute myeloid/T‐lymphoblastic leukaemia (AMTL), is divided across 3 diagnostic categories owing to variable expression of markers deemed to be defining of myeloid and T‐lymphoid lineages, such as myeloperoxidase and CD3. This proposed diagnostic group is supported by (i) retained myeloid differentiation potential during early T cell lymphoid development, (ii) recognition that some cases of acute myeloid leukaemia (AML) harbour hallmarks of T cell development, such as T‐cell receptor gene rearrangements and (iii) common gene mutations in subsets of AML and T cell acute lymphoblastic leukaemia (T‐ALL), including WT1, PHF6, RUNX1 and BCL11B. This proposed diagnostic entity overlaps with early T cell precursor (ETP) T‐ALL and T cell/myeloid mixed phenotype acute leukaemias (MPALs), and also includes a subset of leukaemias currently classified as AML with features of T‐lymphoblastic development. The proposed classification of AMTL as a distinct entity would enable more precise prospective diagnosis and permit the development of improved therapies for patients whose treatment is inadequate with current approaches.     

MYC rearrangement but not extra MYC copies is an independent prognostic factor in patients with mantle cell lymphoma

Mantle cell lymphoma (MCL) with MYC rearrangement (MYC-R) is rare and little is known about the importance of MYC extra copies (EC) in the absence of MYC-R in MCL patients. This study includes 88 MCL patients with MYC tested by fluorescence in situ hybridization and/or conventional cytogenetics, including 27 with MYC-R, 21 with MYC-EC, and 40 with normal MYC-NL. MCL patients with MYC-R more often had blastoid/pleomorphic morphology; a higher frequency of CD10, MYC, and simultaneous MYC and BCL2 expression; a higher level of MYC; and a higher Ki67 proliferation rate (P<0.05) than those without MYC-R. Although patients with MYC-R more frequently received intensive chemotherapy (P=0.001), their overall survival (OS) was significantly shorter than those without MYC-R. Compared with patients with MYC/BCL2 double-hit lymphoma (DHL), patients with MYC-R MCL had a similar OS but more commonly had bone marrow involvement, Ann Arbor stage IV disease, and a different immunophenotype. MCL patients with MYC-EC showed an OS intermediate between those with MYC-R and MYC-NL, either all or only blastoid/pleomorphic MCL patients included. Multivariate analysis showed that MYC-R, but not MYC-EC, had an independent and negative impact on OS. In conclusion, MYC-R but not MYC-EC showed a higher MYC expression and is an adverse prognostic factor for MCL patients. Although the OS of MCL patients with MYC-R is similar to that of MYC/BCL2DHL patients, these groups have different clinicopathologic features supporting the retention of MCL with MYC-R in the category of MCL, as recommended in the revised World Health Organization classification.     

A genome-wide CRISPR screen identifies regulators of MAPK and MTOR pathways that mediate resistance to sorafenib in acute myeloid leukemia

Drug resistance impedes the long-term effect of targeted therapies in acute myeloid leukemia (AML), necessitating the identification of mechanisms underlying resistance. Approximately 25% of AML patients carry FLT3 mutations and develop post-treatment insensitivity to FLT3 inhibitors, including sorafenib. Using a genomewide CRISPR screen, we identified LZTR1, NF1, TSC1 and TSC2, negative regulators of the MAPK and MTOR pathways, as mediators of resistance to sorafenib. Analyses of ex vivo drug sensitivity assays in samples from patients with FLT3-ITD AML revealed that lower expression of LZTR1, NF1, and TSC2 correlated with sensitivity to sorafenib. Importantly, MAPK and/or MTOR complex 1 (MTORC1) activity was upregulated in AML cells made resistant to several FLT3 inhibitors, including crenolanib, quizartinib, and sorafenib. These cells were sensitive to MEK inhibitors, and the combination of FLT3 and MEK inhibitors showed enhanced efficacy, suggesting the effectiveness of such treatment in AML patients with FLT3 mutations and those with resistance to FLT3 inhibitors.     

Venetoclax combines synergistically with FLT3 inhibition to effectively target leukemic cells in FLT3-ITD+ acute myeloid leukemia models

FLT3 internal tandem duplication (FLT3-ITD) mutations account for approximately 25% of adult acute myeloid leukemia (AML) cases and are associated with poor prognosis. Venetoclax, a selective BCL-2 inhibitor, has limited monotherapy activity in relapsed/refractory AML with no responses observed in a small subset of FLT3-ITD+ patients. Further, FLT3-ITD mutations emerged at relapse following venetoclax monotherapy and combination therapy suggesting a potential mechanism of resistance. Therefore, we investigated the convergence of FLT3-ITD signaling on the BCL-2 family proteins and determined combination activity of venetoclax and FLT3-ITD inhibition in preclinical models. In vivo, venetoclax combined with quizartinib, a potent FLT3 inhibitor, showed greater anti-tumor efficacy and prolonged survival compared to monotherapies. In a patient-derived FLT3-ITD+ xenograft model, cotreatment with venetoclax and quizartinib at clinically relevant doses had greater anti-tumor activity in the tumor microenvironment compared to quizartinib or venetoclax alone. Use of selective BCL-2 family inhibitors further identified a role for BCL-2, BCL-XL and MCL-1 in mediating survival in FLT3-ITD+ cells in vivo and highlighted the need to target all three proteins for greatest anti-tumor activity. Assessment of these combinations in vitro revealed synergistic combination activity for quizartinib and venetoclax but not for quizartinib combined with BCL-XL or MCL-1 inhibition. FLT3-ITD inhibition was shown to indirectly target both BCL-XL and MCL-1 through modulation of protein expression, thereby priming cells toward BCL-2 dependence for survival. These data demonstrate that FLT3-ITD inhibition combined with venetoclax has impressive anti-tumor activity in FLT3-ITD+ AML preclinical models and provides strong mechanistic rational for clinical studies.