Development and Validation of Blood-Based Predictive Biomarkers for Response to PD-1/PD-L1 Checkpoint Inhibitors: Evidence of a Universal Systemic Core of 3D Immunogenetic Profiling across Multiple Oncological Indications.

BACKGROUND: Unprecedented advantages in cancer treatment with immune checkpoint inhibitors (ICIs) remain limited to only a subset of patients. Systemic analyses of the regulatory 3D genome architecture linked to individual epigenetic and immunogenetic controls associated with tumour immune evasion mechanisms and immune checkpoint pathways reveal a highly prevalent molecular profile predictive of response to PD-1/PD-L1 ICIs. A clinical blood test based on a set of eight (8) 3D genomic biomarkers has been developed and validated on the basis of an observational trial to predict response to ICI therapy. METHODS: The predictive eight biomarker set is derived from prospective observational clinical trials, representing 280 treatments with Pembrolizumab, Atezolizumab, Durvalumab, Nivolumab, and Avelumab in a broad range of indications: melanoma, lung, hepatocellular, renal, breast, bladder, colon, head and neck, bone, brain, lymphoma, prostate, vulvar, and cervical cancers. RESULTS: The 3D genomic eight biomarker panel for response to immune checkpoint therapy achieved a high accuracy of 85%, sensitivity of 93%, and specificity of 82%. CONCLUSIONS: This study demonstrates that a 3D genomic approach can be used to develop a predictive clinical assay for response to PD-1/PD-L1 checkpoint inhibition in cancer patients.

Immunological profile in cerebrospinal fluid of patients with multiple sclerosis after treatment switch to rituximab and compared with healthy controls.

OBJECTIVE: To investigate changes in the cerebrospinal fluid (CSF) immunological profile after treatment switch from first-line injectables to rituximab in patients with relapsing-remitting MS (RRMS), and to compare the profile in MS patients with healthy controls (HC). METHOD: Cerebrospinal fluid from 70 patients with clinically stable RRMS and 55 HC was analysed by a multiplex electrochemiluminescence method for a broad panel of cytokines and immunoactive substances before, and over a two-year period after, treatment switch to rituximab. After quality assessment of data, using a predefined algorithm, 14 analytes were included in the final analysis. RESULTS: Ten of the 14 analytes differed significantly in MS patients compared with HC at baseline. Levels of IP-10 (CXCL10), IL-12/23p40, IL-6, sVCAM1, IL-15, sICAM1 and IL-8 (CXCL8) decreased significantly after treatment switch to rituximab. The cytokines IP-10 and IL-12/IL-23p40 displayed the largest difference versus HC at baseline and also the largest relative reduction after therapy switch to rituximab. CONCLUSION: We found significant changes in the immunological profile after therapy switch to rituximab in RRMS in the direction towards the values of HC. IP-10 and IL12/IL-23p40 deserve further studies as part of the immunopathogenesis of MS as well as for the mode of action of rituximab in MS.

Neurofilament light in CSF and serum is a sensitive marker for axonal white matter injury in MS.

OBJECTIVE: In an ongoing, open-label, phase 1b study on the intrathecal administration of rituximab for progressive multiple sclerosis, an intraventricular catheter was inserted for drug delivery. The objective of this study was to characterize the limited white matter axonal injury evoked by catheter insertion by analyzing a panel of markers for tissue damage in CSF and serum. METHODS: Lumbar CSF and serum were collected before catheter insertion and at regular intervals during the follow-up period of 1 year. Levels of neurofilament light polypeptide (NF-L), glial fibrillary acidic protein, microtubule-associated protein tau, and S100 calcium binding protein B were measured in the CSF, and NF-L was also quantified in serum at each time point. RESULTS: One month after neurosurgical trauma, there was a distinct peak in NF-L concentration in both CSF and serum. In contrast, the biomarkers S100 calcium binding protein B, glial fibrillary acidic protein, and microtubule-associated protein tau did not show any significant changes. NF-L levels in both CSF and serum peaked at 1 month post surgery, returning to baseline after 6 to 9 months. A strong correlation was observed between the concentrations of NF-L in CSF and serum. CONCLUSIONS: The NF-L level, in CSF and serum, appears to be both a sensitive and specific marker for white matter axonal injury. This makes NF-L a valuable tool with which to evaluate acute white matter axonal damage in a clinical setting. Serum analysis of NF-L may become a convenient way to follow white matter axonal damage longitudinally. CLINICALTRIALSGOV IDENTIFIER: NCT01719159.

Reduced inflammation in relapsing-remitting multiple sclerosis after therapy switch to rituximab.

OBJECTIVE: To describe the effects of switching treatment from ongoing first-line injectable therapies to rituximab on inflammatory activity measured by MRI and levels of CSF neurofilament light chain (CSF-NFL) in a cohort of patients with clinically stable relapsing-remitting multiple sclerosis (RRMS). METHOD: Seventy-five patients with clinically stable RRMS treated with the first-line injectables interferon-ß (IFN-ß) and glatiramer acetate (GA) at 3 Swedish centers were switched to rituximab in this open-label phase II multicenter study. After a run-in period of 3 months, 2 IV doses of 1,000 mg rituximab were given 2 weeks apart followed by repeated clinical assessment, MRI, and CSF-NFL for 24 months. RESULTS: The mean cumulated number of gadolinium-enhancing lesions per patient at months 3 and 6 after treatment shift to rituximab was reduced compared to the run-in period (0.028 vs 0.36, p = 0.029). During the first year after treatment shift, the mean number of new or enlarged T2 lesions per patient was reduced (0.01 vs 0.28, p = 0.004) and mean CSF-NFL levels were reduced by 21% (p = 0.01). CONCLUSIONS: For patients with RRMS, a treatment switch from IFN or GA to rituximab is associated with reduced inflammatory activity measured by MRI and CSF-NFL. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that rituximab has an equal or superior effect in reducing inflammatory activity in RRMS measured by MRI and CSF-NFL compared to first-line injectables during the first year after treatment shift.

Lipocalin-2 is increased in progressive multiple sclerosis and inhibits remyelination.

OBJECTIVE: We aimed to examine the regulation of lipocalin-2 (LCN2) in multiple sclerosis (MS) and its potential functional relevance with regard to myelination and neurodegeneration. METHODS: We determined LCN2 levels in 3 different studies: (1) in CSF and plasma from a case-control study comparing patients with MS (n = 147) with controls (n = 50) and patients with relapsing-remitting MS (n = 75) with patients with progressive MS (n = 72); (2) in CSF and brain tissue microdialysates from a case series of 7 patients with progressive MS; and (3) in CSF at baseline and 60 weeks after natalizumab treatment in a cohort study of 17 patients with progressive MS. Correlation to neurofilament light, a marker of neuroaxonal injury, was tested. The effect of LCN2 on myelination and neurodegeneration was studied in a rat in vitro neuroglial cell coculture model. RESULTS: Intrathecal production of LCN2 was increased predominantly in patients with progressive MS (p < 0.005 vs relapsing-remitting MS) and displayed a positive correlation to neurofilament light (p = 0.005). Levels of LCN2 in brain microdialysates were severalfold higher than in the CSF, suggesting local production in progressive MS. Treatment with natalizumab in progressive MS reduced LCN2 levels an average of 13% (p < 0.0001). LCN2 was found to inhibit remyelination in a dose-dependent manner in vitro. CONCLUSIONS: LCN2 production is predominantly increased in progressive MS. Although this moderate increase does not support the use of LCN2 as a biomarker, the correlation to neurofilament light and the inhibitory effect on remyelination suggest that LCN2 might contribute to neurodegeneration through myelination-dependent pathways.

Levels and Age Dependency of Neurofilament Light and Glial Fibrillary Acidic Protein in Healthy Individuals and Their Relation to the Brain Parenchymal Fraction.

BACKGROUND: Neurofilament light (NFL) and Glial Fibrillary Acidic Protein (GFAP) are integral parts of the axonal and astrocytal cytoskeletons respectively and are released into the cerebrospinal fluid (CSF) in cases of cellular damage. In order to interpret the levels of these biomarkers in disease states, knowledge on normal levels in the healthy is required. Another biomarker for neurodegeneration is brain atrophy, commonly measured as brain parenchymal fraction (BPF) using magnetic resonance imaging (MRI). Potential correlations between levels of NFL, GFAP and BPF in healthy individuals have not been investigated. OBJECTIVES: To present levels of NFL and GFAP in healthy individuals stratified for age, and investigate the correlation between them as well as their correlation with BPF. METHODS: The CSF was analysed in 53 healthy volunteers aged 21 to 70 (1 sample missing for GFAP analysis) and 48 of the volunteers underwent determination of BPF using MRI. RESULTS: Mean (±SD) NFL was 355 ng/L (±214), mean GFAP was 421 ng/L (±129) and mean BPF was 0.867 (±0.035). All three biomarkers correlated with age. NFL also correlated with both GFAP and BPF. When controlled for age, only the correlation between NFL and GFAP retained statistical significance. CONCLUSIONS: This study presents data on age-stratified levels of NFL and GFAP in the CSF of healthy individuals. There is a correlation between levels of NFL and GFAP and both increase with age. A correlation between NFL and BPF was also found, but did not retain statistical significance if controlled for age.

Comparative Assessment of the Prognostic Value of Biomarkers in Traumatic Brain Injury Reveals an Independent Role for Serum Levels of Neurofilament Light.

Traumatic brain injury (TBI) is a common cause of death and disability, worldwide. Early determination of injury severity is essential to improve care. Neurofilament light (NF-L) has been introduced as a marker of neuroaxonal injury in neuroinflammatory/-degenerative diseases. In this study we determined the predictive power of serum (s-) and cerebrospinal fluid (CSF-) NF-L levels towards outcome, and explored their potential correlation to diffuse axonal injury (DAI). A total of 182 patients suffering from TBI admitted to the neurointensive care unit at a level 1 trauma center were included. S-NF-L levels were acquired, together with S100B and neuron-specific enolase (NSE). CSF-NF-L was measured in a subcohort (n = 84) with ventriculostomies. Clinical and neuro-radiological parameters, including computerized tomography (CT) and magnetic resonance imaging, were included in the analyses. Outcome was assessed 6 to 12 months after injury using the Glasgow Outcome Score (1-5). In univariate proportional odds analyses mean s-NF-L, -S100B and -NSE levels presented a pseudo-R2 Nagelkerke of 0.062, 0.214 and 0.074 in correlation to outcome, respectively. In a multivariate analysis, in addition to a model including core parameters (pseudo-R2 0.33 towards outcome; Age, Glasgow Coma Scale, pupil response, Stockholm CT score, abbreviated injury severity score, S100B), S-NF-L yielded an extra 0.023 pseudo-R2 and a significantly better model (p = 0.006) No correlation between DAI or CT assessed-intracranial damage and NF-L was found. Our study thus demonstrates that S-NF-L correlates to TBI outcome, even if used in models with S100B, indicating an independent contribution to the prediction, perhaps by reflecting different pathophysiological processes, not possible to monitor using conventional neuroradiology. Although we did not find a predictive value of NF-L for DAI, this cannot be completely excluded. We suggest further studies, with volume quantification of axonal injury, and a prolonged sampling time, in order to better determine the connection between NF-L and DAI.

Rapid depletion of B lymphocytes by ultra-low-dose rituximab delivered intrathecally.

OBJECTIVE: We are conducting an open-label phase 1b study on the efficacy of intrathecal (IT) administration of rituximab, provided via an Ommaya reservoir, for the treatment of progressive multiple sclerosis (PMS). The objective of this initial study was to monitor B lymphocytes in peripheral blood (PB) and CSF from the first 10 patients 1 year posttreatment. METHODS: Dose titration was performed with daily escalation from 1 mg to 25 mg IT rituximab (n = 3). Lymphocyte subpopulations were monitored daily during dose escalation in PB by flow cytometry and subsequently every 3 months for 1 year, after a total dose of 3 × 25 mg. PB B-lymphocyte subpopulations for the remaining patients (n = 7) were monitored at regular intervals. CSF lymphocyte subpopulations for all patients were monitored by flow cytometry every 2-3 months. RESULTS: The PB B-lymphocyte count dropped rapidly after the first 2 injections (total dose of 3.5 mg IT rituximab) to undetectable levels. Three 25-mg doses given once per week depleted peripheral B lymphocytes entirely for the following 3-6 month period. CONCLUSIONS: Monoclonal antibodies seem to rapidly redistribute to the peripheral compartment following IT injection. Ultra-low doses of rituximab given IT are sufficient to cause complete depletion of peripheral B lymphocytes, indicating that low-dose IT treatment has the potential to be effective in both the CNS and systemic compartments. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with PMS, rituximab provided via an Ommaya reservoir depletes peripheral blood B lymphocytes.

Intense inflammation and nerve damage in early multiple sclerosis subsides at older age: a reflection by cerebrospinal fluid biomarkers.

Inflammatory mediators have crucial roles in leukocyte recruitment and subsequent central nervous system (CNS) neuroinflammation. The extent of neuronal injury and axonal loss are associated with the degree of CNS inflammation and determine physical disability in multiple sclerosis (MS). The aim of this study was to explore possible associations between a panel of selected cerebrospinal fluid biomarkers and robust clinical and demographic parameters in a large cohort of patients with MS and controls (n = 1066) using data-driven multivariate analysis. Levels of matrix metalloproteinase 9 (MMP9), chemokine (C-X-C motif) ligand 13 (CXCL13), osteopontin (OPN) and neurofilament-light chain (NFL) were measured by ELISA in 548 subjects comprising different MS subtypes (relapsing-remitting, secondary progressive and primary progressive), clinically isolated syndrome and persons with other neurological diseases with or without signs of inflammation/infection. Principal component analyses and orthogonal partial least squares methods were used for unsupervised and supervised interrogation of the data. Models were validated using data from a further 518 subjects in which one or more of the four selected markers were measured. There was a significant association between increased patient age and lower levels of CXCL13, MMP9 and NFL. CXCL13 levels correlated well with MMP9 in the younger age groups, but less so in older patients, and after approximately 54 years of age the levels of CXCL13 and MMP9 were consistently low. CXCL13 and MMP9 levels also correlated well with both NFL and OPN in younger patients. We demonstrate a strong effect of age on both inflammatory and neurodegenerative biomarkers in a large cohort of MS patients. The findings support an early use of adequate immunomodulatory disease modifying drugs, especially in younger patients, and may provide a biological explanation for the relative inefficacy of such treatments in older patients at later disease stages.

Modulation of constitutive androstane receptor (CAR) and pregnane X receptor (PXR) by 6-arylpyrrolo[2,1-d][1,5]benzothiazepine derivatives, ligands of peripheral benzodiazepine receptor (PBR).

Constitutive androstane receptor (CAR) and pregnane X receptor (PXR) regulate xenobiotic sensing and metabolism through interactions with multiple exogenous and endogenous chemicals. Compounds that activate CAR are often ligands of PXR; attention is therefore given to discovery of new, receptor-specific chemical entities that may be exploited for therapeutic and basic research purposes. Recently, ligands of the peripheral benzodiazepine receptor (PBR), PK11195 and FGIN-1-27, were shown to modulate both CAR and PXR. PBR is a mitochondrial transport protein responsible for multiple regulatory functions, including heme biosynthesis, a major component in cytochrome P450 (CYP) enzymes. To investigate possible new roles for PBR involvement in metabolic regulation, expression of the CAR and PXR target genes, CYP2B6 and CYP3A4, was measured in human hepatocytes following treatment with a targeted PBR ligand set. Luciferase reporter assays with transiently expressed wild-type CAR (CAR1), splice variant CAR3, or PXR in HuH-7 cells were used to further study activation of these receptors. Four structurally related PBR ligands (benzothiazepines) differentially modulate CAR1, CAR3 and PXR activity. Benzothiazepine NF49 is an agonist ligand of CAR3, a partial agonist of PXR, exhibits greater inverse agonist activity on CAR1 than does PK11195, and is a new tool for studying these closely related nuclear receptors.

Rational quantitative structure-activity relationship (RQSAR) screen for PXR and CAR isoform-specific nuclear receptor ligands.

Constitutive androstane receptor (CAR) and pregnane X receptor (PXR) are closely related orphan nuclear receptor proteins that share several ligands and target overlapping sets of genes involved in homeostasis and all phases of drug metabolism. CAR and PXR are involved in the development of certain diseases, including diabetes, metabolic syndrome and obesity. Ligand screens for these receptors so far have typically focused on steroid hormone analogs with pharmacophore-based approaches, only to find relatively few new hits. Multiple CAR isoforms have been detected in human liver, with the most abundant being the constitutively active reference, CAR1, and the ligand-dependent isoform CAR3. It has been assumed that any compound that binds CAR1 should also activate CAR3, and so CAR3 can be used as a ligand-activated surrogate for CAR1 studies. The possibility of CAR3-specific ligands has not, so far, been addressed. To investigate the differences between CAR1, CAR3 and PXR, and to look for more CAR ligands that may be of use in quantitative structure-activity relationship (QSAR) studies, we performed a luciferase transactivation assay screen of 60 mostly non-steroid compounds. Known active compounds with different core chemistries were chosen as starting points and structural variants were rationally selected for screening. Distinct differences in agonist versus inverse agonist/antagonist effects were seen in 49 compounds that had some ligand effect on at least one receptor and 18 that had effects on all three receptors; eight were CAR1 ligands only, three were CAR3 only ligands and four affected PXR only. This work provides evidence for new CAR ligands, some of which have CAR3-specific effects, and provides observational data on CAR and PXR ligands with which to inform in silico strategies. Compounds that demonstrated unique activity on any one receptor are potentially valuable diagnostic tools for the investigation of in vivo molecular targets.

Non-homologous end-joining gene profiling reveals distinct expression patterns associated with lymphoma and multiple myeloma.

Repair of DNA strand breaks induced during lymphoid antigen receptor rearrangement involves non-homologous end-joining (NHEJ). We investigated NHEJ in the aetiology of lymphoproliferative disorders (LPDs) and the disease subtypes therein through real-time quantitative RT-PCR gene expression analysis. Lower expression of XRCC6 and MRE11A was observed in all tumours, with higher expression of both XRCC4 and RAD50 observed only in multiple myeloma (MM). Hierarchical clustering enabled tumours to be clearly distinguished from controls, and by morphological sub-type. We postulate this identifies targets worthy of investigation in the genetic predisposition, pathogenesis and prognosis of lymphoid malignancies.

Proteomic evaluation of pathways associated with dexamethasone-mediated apoptosis and resistance in multiple myeloma.

We have used global protein expression analysis to characterize the pathways of dexamethasone-mediated apoptosis and resistance in myeloma. Analysis of MM.1S cells by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) identified a series of proteins that were up- and downregulated following dexamethasone treatment. Downregulated proteins included proteins involved in cell survival and proliferation, whereas upregulated proteins were involved in post-translational modification, protein folding and trafficking. A comparison with published gene expression studies identified FK binding protein 5 (FKBP5) (also known as FKBP51), a key regulatory component of the Hsp90-steroid-receptor complex to be increased at the mRNA and protein level postdexamethasone exposure. Quantitative real time polymerase chain reaction and 2D-PAGE analysis of the dexamethasone resistant cell line MM.1R demonstrated no increase in FKBP5, consistent with its association with dexamethasone-mediated apoptosis. Western blot analysis of FKBP5 and other members of the Hsp90-receptor complex showed an increase in FKBP5 whilst FKBP4 (also known as FKBP52) and Hsp90 expression remained constant. No changes were observed in MM.1R. In conclusion, we demonstrated that following steroid receptor signalling, the cell carries out a number of adaptive responses prior to cell death. Interfering with these adaptive responses may enhance the myeloma killing effect of dexamethasone.

A global expression-based analysis of the consequences of the t(4;14) translocation in myeloma.

PURPOSE: Our purpose in this report was to define genes and pathways dysregulated as a consequence of the t(4;14) in myeloma, and to gain insight into the downstream functional effects that may explain the different prognosis of this subgroup. EXPERIMENTAL DESIGN: Fibroblast growth factor receptor 3 (FGFR3) overexpression, the presence of immunoglobulin heavy chain-multiple myeloma SET domain (IgH-MMSET) fusion products and the identification of t(4;14) breakpoints were determined in a series of myeloma cases. Differentially expressed genes were identified between cases with (n = 5) and without (n = 24) a t(4;14) by using global gene expression analysis. RESULTS: Cases with a t(4;14) have a distinct expression pattern compared with other cases of myeloma. A total of 127 genes were identified as being differentially expressed including MMSET and cyclin D2, which have been previously reported as being associated with this translocation. Other important functional classes of genes include cell signaling, apoptosis and related genes, oncogenes, chromatin structure, and DNA repair genes. Interestingly, 25% of myeloma cases lacking evidence of this translocation had up-regulation of the MMSET transcript to the same level as cases with a translocation. CONCLUSIONS: t(4;14) cases form a distinct subgroup of myeloma cases with a unique gene signature that may account for their poor prognosis. A number of non-t(4;14) cases also express MMSET consistent with this gene playing a role in myeloma pathogenesis.

Insights into the multistep transformation of MGUS to myeloma using microarray expression analysis.

To define specific pathways important in the multistep transformation process of normal plasma cells (PCs) to monoclonal gammopathy of uncertain significance (MGUS) and multiple myeloma (MM), we have applied microarray analysis to PCs from 5 healthy donors (N), 7 patients with MGUS, and 24 patients with newly diagnosed MM. Unsupervised hierarchical clustering using 125 genes with a large variation across all samples defined 2 groups: N and MGUS/MM. Supervised analysis identified 263 genes differentially expressed between N and MGUS and 380 genes differentially expressed between N and MM, 197 of which were also differentially regulated between N and MGUS. Only 74 genes were differentially expressed between MGUS and MM samples, indicating that the differences between MGUS and MM are smaller than those between N and MM or N and MGUS. Differentially expressed genes included oncogenes/tumor-suppressor genes (LAF4, RB1, and disabled homolog 2), cell-signaling genes (RAS family members, B-cell signaling and NF-kappaB genes), DNA-binding and transcription-factor genes (XBP1, zinc finger proteins, forkhead box, and ring finger proteins), and developmental genes (WNT and SHH pathways). Understanding the molecular pathogenesis of MM by gene expression profiling has demonstrated sequential genetic changes from N to malignant PCs and highlighted important pathways involved in the transformation of MGUS to MM.

Polymorphic variation in GSTP1 modulates outcome following therapy for multiple myeloma.

Glutathione S-transferase P1 (GSTP1) is a phase 2 drug metabolism enzyme involved in the metabolism and detoxification of a range of chemotherapeutic agents. A single nucleotide polymorphism (Ile105Val) results in a variant enzyme with lower thermal stability and altered catalytic activity. We hypothesized that patients with the less stable variant have a decreased ability to detoxify chemotherapeutic substrates, including melphalan, and have an altered outcome following treatment for multiple myeloma. We have assessed the impact of GSTP1 codon 105 polymorphisms in 222 patients entered into the Medical Research Council (MRC) myeloma VII trial (comparing standard-dose chemotherapy with high-dose therapy). In the standard-dose arm, patients with the variant allele (105Val) had an improved progression-free survival (PFS) (adjusted hazard ratios for PFS were 0.55 for heterozygotes and 0.52 for 105Val homozygotes, compared with 105Ile homozygotes; P for trend =.04); this was supported by a trend to improved overall survival, greater likelihood of entering plateau and shorter time to reach plateau in patients with the 105Val allele. No difference in outcome by genotype was found for patients treated with high-dose therapy. However, the progression-free survival advantage of the high-dose arm was seen only in patients homozygous for 105Ile (P =.008).

Genomic characterization of the chromosomal breakpoints of t(4;14) of multiple myeloma suggests more than one possible aetiological mechanism.

Using FISH-based techniques, rearrangements of the immunoglobulin heavy-chain (IgH) locus at 14q32 have been found in the majority of cases of multiple myeloma (MM). Some of these IgH translocations are recurrent and we have characterized the genomic breakpoints of seven t(4;14) translocations from MM patients, using a combination of vectorette and conventional polymerase chain reaction methods, the aim being to understand the molecular mechanism leading to MM. Conventionally, the chromosome 14q32 breakpoints in these reciprocal translocations are believed to be located in the IgH mu switch (S) region and a further downstream S region with deletion of intervening DNA occurring as a result of aberrant class switch recombination (CSR); this was seen in five of the cases analysed. However, in two patients it was possible to demonstrate that the rearranged hybrid switch region sequence was joined to DNA from chromosome 4p16, suggesting that IgH translocations can occur in B cells that have already undergone legitimate CSR. The complex nature of these rearrangements leads us to speculate that primary IgH translocations may occur at different time points in the development in MM plasma cells, either at the time of physiological CSR or at a later stage, possibly involving a different mechanism.

CYP1A1*2B (Val) allele is overrepresented in a subgroup of acute myeloid leukemia patients with poor-risk karyotype associated with NRAS mutation, but not associated with FLT3 internal tandem duplication.

The etiology of acute myeloid leukemia (AML) is largely unknown. Biologic and epidemiologic data implicate exogenous toxicants, including cytotoxic drugs, benzene, radiation, and cigarette smoking. Allelic variation in genes encoding enzymes such as NADP(H) quinone oxidoreductase (NQO1) and glutathione S-transferase T1 (GSTT1) that metabolize environmental toxicants predispose to subtypes of AML, including therapy-related AML. We assayed NRAS oncogene mutation and FLT3 internal tandem duplication in 447 AML patients with an abnormal karyotype treated in Medical Research Council (MRC) AML clinical trials. Functional allelic variant frequencies in genes encoding carcinogen-metabolizing enzymes GSTT1, GSTM1, CYP1A1, CYP2D6, CYP2C19, SULT1A1, and NQO1 were previously determined for this cohort. FLT3 internal tandem duplication (ITD) frequency was 17%, and NRAS mutation 12% for the entire cohort. The 2 mutations were found together in only 4 patients. No association was found between enzyme allelic variant frequencies and the presence of FLT3 ITD for the entire cohort or within cytogenetic subgroups. CYP1A1*2B (Val) high-inducibility variant allele was overrepresented in patients with NRAS mutation compared with no mutation, for (1) the entire AML cohort (n = 8/53 vs 26/371; odds ratio [OR] = 2.36; 95% confidence interval [CI] 1.01-5.53) and (2) the poor-risk karyotype group (n = 6/14 vs 4/89; OR = 15.94; 95% CI 3.71-68.52) comprising patients with partial/complete deletion of chromosome 5 or 7, or abnormalities of chromosome 3. The CYP1A1*2B allele may predispose to the development of these subgroups of AML by augmented phase 1 metabolism to highly reactive intermediates of CYP1A1 substrates, including polycyclic aromatic hydrocarbons, or by generation of oxidative stress as a metabolic by-product.

A molecular study of the t(4;14) in multiple myeloma.

The t(4;14) translocation is found in approximately 10% of myeloma patients and results in the deregulation of at least two genes, MMSET and fibroblast growth factor receptor 3 (FGFR3), with the formation of a fusion product between MMSET and the immunoglobulin heavy chain (IgH) locus and overexpression of FGFR3. We have analysed a series of 80 patient samples, comprising 67 multiple myeloma (MM) cases and 13 monoclonalgammopathy of undetermined significance (MGUS) cases, using RT-PCR to detect IgH-MMSET fusions. The t(4;14) translocation was detected in 7/67 (10%) myeloma cases and all seven expressed FGFR3 which was not seen in t(4;14)-negative myeloma cases. In the MGUS cases, a similar proportion of t(4;14)-positive cases was found (2/13; 15%), but none of these expressed FGFR3. All patients with detectable FGFR3 expressed both the FGFR3 IIIb and FGFR3 IIIc isoforms, the result of alternative splicing in the ligand binding domain, and exon-deleted variants of FGFR3. We also identified a cryptic splice site in MMSET which results in a 277 amino acid deletion downstream of the breakpoint on der(4). FGFR3 mutation analysis revealed no mutations in the presenting myeloma or MGUS samples. However, we also had access to paired presentation and relapse samples which had been taken from a patient 13 months apart. Both samples had the t(4;14) translocation and overexpressed FGFR3, but only the relapse sample possessed the K650E mutation in the kinase domain of FGFR3. This suggests that targeted mutation in the translocated FGFR3 gene when under the control of the immunoglobulin promoters can occur and may provide one mechanism for disease progression.