Gene Expression Profiling of Microdissected Hodgkin Reed Sternberg Cells: Molecular Subtypes and Treatment Outcome Correlations.
Bibliographic record
Abstract
Abstract Abstract 268 INTRODUCTION: Classical Hodgkin lymphoma (cHL) is unique among lymphomas due to the scarcity of the malignant Hodgkin Reed Sternberg (HRS) cells, which are derived from clonal germinal center B cells. Investigations using laser capture microdissection permit more detailed analysis of these cells. However, most recent studies were limited by low case numbers and lack of available clinical data. PATIENTS AND METHODS: We studied 29 cases of cHL and the 5 HL lines KMH2, HDLM2, L428, L540, and L1236 by gene expression profiling. All patients were treated at the BC Cancer Agency between 1984 and 2006 and received at least 4 cycles of polychemotherapy and stage-dependent radiotherapy. The cohort also included 5 biopsies taken at relapse. Treatment failure was defined as disease progression or relapse at any time (n=14) after initiation of treatment; treatment success as absence of progression (n=15). We used laser microdissection (Molecular Machines & Industries Cellcut with Nikon Eclipse TE2000-S microscope) to study the enriched HRS cell compartment separately from the microenvironment. RNA extraction was performed on pools of 1000 microdissected HRS cells in each case. Gene expression profiles were generated using Affymetrix HG UA133 2.0 Plus arrays using two-cycle labeling reactions. HRS cell profiles were compared to microdissected germinal centers (GC), and HL cell line profiles compared to enriched tonsillar CD77+ centroblasts (MACS cell separation, Miltenyi). Furthermore, we compared gene expression profiles of treatment failures to those of treatment successes. RESULTS: We identified 1342 differentially expressed probesets (fold change >5, False Discovery Rate (FDR) adjusted p value <0.001) between HRS and GC cells. Using overrepresentation analysis we found genes involved in NFκB, JAK/Stat, IL-6, IL-9 signaling, cytotoxic T lymphocyte-mediated apoptosis and IL-15 production to be significantly over-expressed in HRS cells and genes involved in B cell, T cell receptor signaling and many transcriptional regulators such as FOXO1, E2F5, IRF8, NFATC1, NFYB, POU2AF1 to be significantly under-expressed in HRS cell. Comparison of these data to differentially expressed genes in the HL cell lines (1004 genes, fold change >5, FDR-adjusted p value <0.001) showed significant overlap of genes involved in proliferation, apoptosis, IL15 signaling and B cell receptor signaling, while overrepresentation of metabolism genes was unique to the cell lines. Hierarchical clustering of all 29 primary HL cases identified 3 separate clusters characterized by 1) a cytotoxic signature, 2) TNF/TGFB receptor signaling or 3) a residual B cell signature. Dichotomizing the profiles into the two treatment outcome groups demonstrated that NFγB signaling, complement system genes and genes involved in the developmental process of hematopoietic progenitor cells, macrophages and blood vessels were overexpressed in treatment failure samples. DISCUSSION: Using microdissection of HRS cells in a large number of cases we were able to further characterize the unique expression program of HL and refine the data inventory about dysregulated cellular functions and pathways in this disease. Overexpression of genes associated with NFκB, complement and hematopoietic progenitor cells proliferation correlate strongly with treatment failure. Further study using immunohistochemistry is currently ongoing to validate these findings and to develop clinically useful biomarkers. Disclosures: Gascoyne: Roche Canada: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".