We attended the annual meeting of the American Society of Hematology (ASH) in San Diego. The convention center was abuzz with scientists sharing their research on the clinical utility of stem cells, the mechanics of the blood cell foundry, new therapeutics for sickle cell disease and a variety of other topics.
We were especially interested in the work presented on cell-of-origin (COO) subtyping in diffuse large B-cell lymphoma (DLBCL) DLBCL is a distinct histological type within mature B-cell Non-Hodgkin lymphoma (NHL) that is characterized by large tumor cells and aggressive clinical behavior. DLBCL is the most common form of NHL, accounting for 25–40% of NHL cases and an estimated annual incidence of over 25,000 cases in the United States. Standard treatment for newly diagnosed DLBCL involves immunochemotherapy and the most commonly administered immunochemotherapy treatment worldwide is rituximab in combination with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). However, DLBCL is a heterogeneous disease and clinical studies have shown that over 30% of patients relapse when given R-CHOP as a first line treatment in DLBCL (Feugier, 2005 and Sehn, 2007), underscoring the need for biomarkers that can accurately identify those patients at higher risk of relapse, and/or for identifying those patients that may benefit from alternative treatment regimens to R-CHOP.
Although DLBCL tumors exhibit similar histology, they are heterogeneous at the molecular level (Alizadeh, 2000; Rosenwald, 2002). Gene expression profiling classifies DLBCL into two main subtypes, germinal center B-cell-like (GCB) an activated B-cell-like (ABC) molecular subtypes plus an additional smaller subset of “unclassified” tumors, based on the expression of a unique subset of genes related to each subtype. The subtyping terminology of GCB/ABC is referred to as the “Cell-of-origin” classification (COO). The ABC/GCB molecular subtypes of DLBCL are now recognized within the WHO guidelines (Swerdlow, 2016). The most recent WHO guideline requires ABC/GCB subtype classification for all newly diagnosed DLBCL patients. However, there are no FDA cleared or approved IVDs to identify the GCB and ABC subtypes. Several attempts have been made to develop IHC assays and algorithms, as a surrogate for gene expression profiling, to discriminate between DLBCL subtypes. The guidelines recommend the use of GEP-based methods for subtyping given their robustness and reported accuracy; however, IHC-based methods are still considered acceptable given the current lack of availability of gene expression profiling -based methods despite the observation in a meta-analysis comparing immunohistochemical assignment with the use of gene expression profiling which found that two of the most commonly employed immunohistochemical algorithms (Hans, Choi) failed to identify significant differences in overall survival while methods based on gene expression retained reliability at doing so (Read, Clin Lymph Myel Leuk 2014;14:460-7). In addition, the IHC-based methods only distinguish two classes: GCB and non-GCB where non-GCB includes ABC and unclassified without differentiating between these two subtypes (Hans, 2004).
Therefore, a reliable assay is needed for accurate and consistent classification of COO subtypes. NanoString is developing an investigational in vitro diagnostic assay using the gene expression profile of cells found in DLBCL tissue for the classification of COO subtype of DLBCL (ABC or GCB type). Samples that have less than 90% probability of being classified with confidence as either subtype based on their gene expression profile are referred to as unclassified. The investigational test is performed on the NanoString nCounter® Dx Analysis System using RNA extracted from formalin fixed, paraffin embedded (FFPE) tumor tissue diagnosed by pathology as DLBCL.
Several of the studies presented at the ASH session entitled “Aggressive Lymphoma (Diffuse Large B-Cell and Other Aggressive B-Cell Non-Hodgkin Lymphomas)—Results from Prospective Clinical Trials: Novel Approaches in Aggressive Lymphoma” included COO subtyping performed with NanoString’s investigational lymphoma subtyping test.
Study of Gazyva vs. Rituxan in Newly Diagnosed DLBCL
GOYA, a randomized Phase III study, compared the efficacy and safety of a next-generation of CD20 antibody, Gazyva® in combination with R-CHOP vs the standard of care R-CHOP in newly diagnosed DLCBL. The GOYA study randomized 1,418 patients at 207 centers globally, representing one of the largest randomized trials in DLBCL. For the primary analysis, G-CHOP was found to not improve progression-free survival (PFS) compared with R-CHOP in previously untreated patients with DLBCL.
We were interested to learn that the study also found that consistent with previous findings in prognosis by COO, the ABC subtype as determined by the NanoString lymphoma subtyping assay had an inferior survival as compared to the GCB subtype. Furthermore, in an exploratory analysis, there was a trend towards a greater survival benefit from G-CHOP over R-CHOP in the GCB subtype.
Investigating a Different Immunochemotherapy Regimen vs. Standard of Care
The primary objective of CALGB 50303 , a randomized Phase III study, was to compare event-free survival (EFS) of R-CHOP versus DA-EPOCH-R (dose adjusted-etoposide prednisolone oncovin cyclophosphamide hydroxydaunorubicin rituximab) in untreated DLBCL. For the overall population, no difference was observed in three-year EFS or three-year overall survival, and no clinical subgroup was identified that appears to benefit from DA-EPOCH-R over R-CHOP.
We look forward to reviewing the molecular profile analysis including cell-of-origin analysis (currently pending) when it is available, as such analyses may identify prognostic subsets, new therapeutic targets and new biomarkers for response or toxicity.
Investigating DLBCL Maintenance with Lenalidomide in an Older Population
REMARC is an international, multicenter, randomized Phase III trial that assessed the benefit of lenalidomide maintenance after response to R-CHOP in patients aged 60 to 80 years with previously untreated DLBCL.
The study’s authors shared that REMARC achieved its primary endpoint of a statistically significant and clinically meaningful improvement in PFS for patients receiving lenalidomide. However, at a median follow-up of 52 months, the analysis of overall survival, a key secondary endpoint, showed no difference between the lenalidomide and placebo arms. We were interested to learn that although there were some differences observed between lenalidomide and placebo within specific COO subtypes as determined by the NanoString lymphoma subtyping assay, no statistical significance was reached between lenalidomide and placebo in specific subtypes.
The NanoString lymphoma subtyping assay is currently being used to select patients for a Phase III clinical trial to evaluate lenalidomide plus R-CHOP immunochemotherapy versus placebo plus R-CHOP in patients who have newly diagnosed, previously untreated ABC-type DLBCL (ROBUST study, NCT02285062). The Lymphoma Subtyping Test (LST) for use on the nCounter Dx Analysis System is for investigational use only. Limited by United Stated law to investigational use.
- Nowakowski GS, Czuczman MS, “ABC, GCB, and Double-Hit Diffuse Large B-Cell Lymphoma: Does Subtype Make a Difference in Therapy Selection?” Am Soc Clin Oncol Educ Book, 2015, doi: 10.14694/EdBook_AM.2015.35.e449.
- Vitolo U, Sehn, LH, et al. (2016, December). Obinutuzumab or Rituximab Plus CHOP in Patients with Previously Untreated Diffuse Large B-Cell Lymphoma: Final Results from an Open-Label, Randomized Phase 3 Study (GOYA). Paper presented at the annual meeting of the American Society of Hematology, San Diego, CA.
- Wilson WH, Leonard, JP, et al. (2016, December). Phase III Randomized Study of R-CHOP Versus DA-EPOCH-R and Molecular Analysis of Untreated Diffuse Large B-Cell Lymphoma: CALGB/Alliance 50303. Paper presented at the annual meeting of the American Society of Hematology, San Diego, CA.
- Thieblemont C, Coiffier B, et al. (2016 December). First Analysis of an International Double-Blind Randomized Phase III Study of Lenalidomide Maintenance in Elderly Patients with DLBCL Treated with R-CHOP in First Line, the Remarc Study from Lysa. Paper presented at the annual meeting of the American Society of Hematology, San Diego, CA.