The incidence, natural history, biology, and treatment of transformed lymphomas

Treatment Outcome in Patients with Primary or Secondary Transformed Indolent B-Cell Lymphomas

BACKGROUND

Histologic transformation (HT) of indolent B-cell lymphomas into an aggressive form can occur simultaneously (primary HT, pHT) or sequentially after a preceding diagnosis of indolent lymphoma (secondary HT, sHT). The clinical course after diagnosis of HT is variable.

OBJECTIVES

To describe the outcome of treatment in pHT and sHT patients.

METHODS

We retrospectively analyzed HT cases with an underlying follicular lymphoma, nodal marginal zone lymphoma, extranodal marginal zone lymphoma, lymphoplasmacytic lymphoma, or small lymphocytic lymphoma at our institution. Kaplan-Meier estimates were used to calculate progression-free survival (PFS) and overall survival (OS).

RESULTS

Ninety-two HT patients were identified, 38 with pHT and 54 with sHT. In sHT, time-to-transformation was not influenced by the preceding treatment strategy of the indolent lymphoma component. In pHT, median PFS was 61 months (95% CI 27-61), and OS was not reached. In sHT, median PFS and OS was 14 months (95% CI 9-32) and 42 months (95% CI 16-90), respectively. Significant differences between pHT and sHT in PFS (p = 0.002; Hazard ratio [HR] 2.30, 95% CI 1.36-3.91) and OS (p = 0.0001; HR 3.30, 95% CI 1.81-6.03) were observed. Response to treatment for transformation was highly prognostic of PFS and OS (p < 0.0001).

CONCLUSIONS

The outcome in pHT cases is favorable and signifi-cantly better than in sHT cases. Failure to achieve a remission after treatment for transformation confers a dismal pro-gnosis.

A rare case of follicular lymphoma transformed to a high-grade B-cell lymphoma in orbit

Transformation of lymphoma is an infrequent phenomenon, and involvement of the eye as such is even uncommon. Histological transformation in patients with follicular lymphoma who were previously treated with immune-chemotherapy carry a poor outcome. Here, we illustrate such a case with aggressive histological transformation from a low-grade lymphoma.

Multimodality imaging of indolent B cell lymphoma from diagnosis to transformation: what every radiologist should know

Indolent B cell lymphomas are a group of lymphoid malignancies characterized by their potential to undergo histologic transformation to aggressive lymphomas. While different subtypes of indolent B cell lymphomas demonstrate specific clinical and imaging features, histologic transformation can be suspected on cross-sectional imaging when disproportionate lymph node enlargement or new focal lesions in extranodal organs are seen. On PET/CT, transformed indolent lymphoma may show new or increased nodal FDG avidity or new FDG-avid lesions in different organs. In this article, we will (1) review the imaging features of different subtypes of indolent B cell lymphomas, (2) discuss the imaging features of histologic transformation, and (3) propose a diagnostic algorithm for transformed indolent lymphoma. The purpose of this review is to familiarize radiologists with the spectrum of clinical and imaging features of indolent B cell lymphomas and to define the role of imaging in raising concern for transformation and in guiding biopsy for confirmation.

Transformation in Low-grade B-cell Neoplasms

Low-grade B-cell leukemias/lymphomas are a diverse group of indolent lymphoproliferative disorders that are typically characterized by good patient outcomes and long life expectancies. A subset of cases, however, undergo histologic transformation to a higher-grade neoplasm, a transition associated with a more aggressive clinical course and poor survival. Transformation of follicular lymphoma to diffuse large B-cell lymphoma and Richter transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma are best characterized in the literature. This article reviews clinical and pathologic characteristics of these most common forms of transformation, with an emphasis on salient histologic, immunophenotypic, and genetic features.

Emerging understanding of Bcl-2 biology: Implications for neoplastic progression and treatment

Bcl-2, the founding member of a family of apoptotic regulators, was initially identified as the protein product of a gene that is translocated and overexpressed in greater than 85% of follicular lymphomas (FLs). Thirty years later we now understand that anti-apoptotic Bcl-2 family members modulate the intrinsic apoptotic pathway by binding and neutralizing the mitochondrial permeabilizers Bax and Bak as well as a variety of pro-apoptotic proteins, including the cellular stress sensors Bim, Bid, Puma, Bad, Bmf and Noxa. Despite extensive investigation of all of these proteins, important questions remain. For example, how Bax and Bak breach the outer mitochondrial membrane remains poorly understood. Likewise, how the functions of anti-apoptotic Bcl-2 family members such as eponymous Bcl-2 are affected by phosphorylation or cancer-associated mutations has been incompletely defined. Finally, whether Bcl-2 family members can be successfully targeted for therapeutic advantage is only now being investigated in the clinic. Here we review recent advances in understanding Bcl-2 family biology and biochemistry that begin to address these questions.

Transformed follicular non-Hodgkin lymphoma

Histologic transformation of follicular lymphoma to an aggressive non-Hodgkin lymphoma is a critical biologic event with profound implications on the natural history of this otherwise indolent disease. Recent insights into the genetic and epigenetic basis of transformation have been described, with the recognition of pivotal events governing the initiation and persistence of tumor evolution. Outcomes of patients with transformed lymphoma have historically been poor; however, several studies in the rituximab era suggest that survival may be more favorable than previously recognized. This review highlights our current understanding of transformed follicular lymphoma biology and pathogenesis, current treatment, and future directions.

BCL2 mutations are associated with increased risk of transformation and shortened survival in follicular lymphoma

Follicular lymphoma (FL), an indolent neoplasm caused by a t(14;18) chromosomal translocation that juxtaposes the BCL2 gene and immunoglobulin locus, has a variable clinical course and frequently undergoes transformation to an aggressive lymphoma. Although BCL2 mutations have been previously described, their relationship to FL progression remains unclear. In this study, we evaluated the frequency and nature of BCL2 mutations in 2 independent cohorts of grade 1 and 2 FLs, along with the correlation between BCL2 mutations, transformation risk, and survival. The prevalence of BCL2 coding sequence mutations was 12% in FL at diagnosis and 53% at transformation (P < .0001). The presence of these BCL2 mutations at diagnosis correlated with an increased risk of transformation (hazard ratio 3.6; 95% CI, 2.0-6.2; P < .0001) and increased risk of death due to lymphoma (median survival of 9.5 years with BCL2 mutations vs 20.4 years without; P = .012). In a multivariate analysis, BCL2 mutations and high FL international prognostic index were independent risk factors for transformation and death due to lymphoma. Some mutant Bcl-2 proteins exhibited enhanced antiapoptotic capacity in vitro. Accordingly, BCL2 mutations can affect antiapoptotic Bcl-2 function, are associated with increased activation-induced cytidine deaminase expression, and correlate with increased risk of transformation and death due to lymphoma.

Intraclonal diversity in follicular lymphoma analyzed by quantitative ultradeep sequencing of noncoding regions

Cancers are characterized by genomic instability, and the resulting intraclonal diversity is a prerequisite for tumor evolution. Therefore, metrics of tumor heterogeneity may prove to be clinically meaningful. Intraclonal heterogeneity in follicular lymphoma (FL) is apparent from studies of somatic hypermutation (SHM) caused by activation-induced deaminase (AID) in IGH. Aberrant SHM (aSHM), defined as AID activity outside of the IG loci, predominantly targets noncoding regions causing numerous "passenger" mutations, but it has the potential to generate rare significant "driver" mutations. The quantitative relationship between SHM and aSHM has not been defined. To measure SHM and aSHM, ultradeep sequencing (>20,000-fold coverage) was performed on IGH (~1650 nt) and nine other noncoding regions potentially targeted by AID (combined 9411 nt), including the 5' untranslated region of BCL2. Single-nucleotide variants (SNVs) were found in 12/12 FL specimens (median 136 SHMs and 53 aSHMs). The aSHM SNVs were associated with AID motifs (p < 0.0001). The number of SNVs at BCL2 varied widely among specimens and correlated with the number of SNVs at eight other potential aSHM sites. In contrast, SHM at IGH was not predictive of aSHM. Tumor heterogeneity is apparent from SNVs at low variant allele frequencies; the relative number of SNVs with variable allele frequency < 5% varied with clinical grade, indicating that tumor heterogeneity based on aSHM reflects a clinically meaningful parameter. These data suggest that genome-wide aSHM may be estimated from aSHM of BCL2 but not SHM of IGH. The results demonstrate a practical approach to the quantification of intratumoral genetic heterogeneity for clinical specimens.

Survival of patients with transformed lymphoma in the rituximab era

In the pre-rituximab era, transformation of indolent B-cell lymphoma to diffuse large B-cell lymphoma (DLBCL) was associated with an extremely poor outcome and a median post-transformation survival ranging from 1 to 2 years. We evaluated the impact of rituximab-cyclophosphamide, adriamycin, vincristine, prednisone (R-CHOP) on the survival outcomes of transformed lymphoma compared with de novo DLBCL. Between 2002 and 2010, 317 DLBCL patients who were consecutively diagnosed and treated with R-CHOP were identified at our institution. Patients with transformed lymphoma were included if they had not previously received R-CHOP. Patient characteristics, treatment, and outcome data were retrospectively collected. Sixty patients (19 %) had transformed lymphoma of which 37 (62 %) had transformed from follicular lymphoma, 50 (83 %) were chemotherapy naïve, and 58 (96 %) were rituximab naïve at the time of treatment. With a median follow-up of 31.4 months, 231 patients achieved either complete response or complete response unconfirmed (73 %) with no significant difference between de novo DLBCL (n = 192, 75 %) and the transformed group (n = 39, 65 %) (P = 0.25). Six patients (15 %) relapsed in the transformed group at a median time to relapse of 29.3 months. The 2-year and 5-year overall survivals for all patients were 82 and 72 %, respectively. The overall and progression-free survivals for transformed lymphoma and de novo DLBCL were not statistically different (P = 0.45 and P = 0.38, respectively). With R-CHOP chemotherapy, the prognosis of transformed lymphoma in patients with minimal chemotherapy exposure for indolent disease is similar to that of de novo DLBCL.

High-dose therapy with autologous stem cell support for lymphoma--from experimental to standard treatment

High-dose therapy with autologous stem cell support (HDT) has been a therapeutic option for lymphomas in Norway since as far back as 1987. By restoring bone marrow function through reinfusion of the patient's own stem cells, it is possible to administer cancer treatment in higher and otherwise lethal doses, and thereby achieve better treatment results. Originally stem cells were harvested from bone marrow and the high-dose therapy included total body irradiation, but since the mid 1990s stem cells have been harvested by apheresis and the high-dose therapy has consisted of chemotherapy alone (BEAM chemotherapy). In 1995 the treatment was regionalised and since then it has been performed in all health regions. The HDT procedure was introduced as an experimental treatment in clinical studies with international collaboration. The indications have changed over time, and this is now established treatment for a number of types of lymphoma.

Immunomodulation therapy with lenalidomide in follicular, transformed and diffuse large B cell lymphoma: current data on safety and efficacy

Lenalidomide is an immunomodulatory agent which has been approved for multiple myeloma. Lenalidomide is also effective in and tolerated well by patients with follicular lymphoma, diffuse large B-cell lymphoma, and transformed large cell lymphoma. This review summarizes the results of current preclinical and clinical studies of lenalidomide, alone or in combination with the monoclonal antibody rituximab, as a therapeutic option for these three lymphoma types. This review will serve as a tool guiding future clinical investigations to improve survival rates for these three lymphomas.

90Yttrium-Ibritumomab-Tiuxetan as First-Line Treatment for Follicular Lymphoma: 30 Months of Follow-Up Data From an International Multicenter Phase II Clinical Trial

Purpose

We report on a multicenter phase II trial of 90yttrium-ibritumomab-tiuxetan (90YIT) as first-line stand-alone therapy for patients with follicular lymphoma (FL).

Patients and Methods

Fifty-nine patients with CD20+ FL grade 1 to 3a in stages II, III, or IV, age 50 years old or older requiring therapy were enrolled. They received 90YIT according to standard procedure. If complete response (CR) or unconfirmed complete response (CRu) without evidence for minimal residual disease (MRD) 6 months after application of 90YIT was achieved, patients were observed without further intervention. The same applied to patients with partial response (PR) or with stable disease (SD). Patients with CR but with persisting MRD were to receive a consolidation treatment with rituximab. Primary end point was the clinical and molecular response rate. Secondary end points were time to progression, safety, and tolerability.

Results

Six months after treatment with 90YIT, 56% of the patients showed a CR or CRu and 31% achieved a PR. After a median follow-up of 30.6 months, the progression-free survival (PFS) was 26 months. There was a trend for shorter PFS in patients with increased lactate dehydrogenase (LDH). Of the 26 patients who had CR 12 months after 90YIT, only three had relapsed. Median time to next treatment has not been reached. The most common toxicities were transient thrombocytopenia and leukocytopenia. Nonhematologic toxicities never exceeded grade 2 according to Common Terminology Criteria for Adverse Events (CTCAE v2.0).

Conclusion

90YIT is well tolerated and achieves high response rates. Patients with increased LDH tend to relapse earlier, and individuals in remission 1 year after 90YIT appear to have long- lasting responses.

Dissecting follicular lymphoma: high versus low risk

Progress in the management of follicular lymphoma (FL) has translated to improved outcomes, with most patients surviving a decade or more from the time of diagnosis. However, the disease remains quite heterogeneous and a substantial number of patients have more aggressive disease with short responses to therapy and/or transformation to higher-grade lymphomas. Given the lack of a single standard approach, it is important to understand sources of heterogeneity among patients that influence initial management, surveillance strategies, and overall prognosis. Most of the validated tools, such as the Follicular Lymphoma International Prognostic Index (FLIPI) and FLIPI-2, apply to the frontline setting, and there is an unmet need for prognostic tools in relapsed and refractory disease states. In particular, the number of prior treatment regimens may be less important than the duration of response to the most recent regimen and the type of prior therapy received. Furthermore, despite awareness of progressive genetic and epigenetic derangements and a growing appreciation of the microenvironment's role in FL outcomes, there is no validated means of incorporating biologic data into clinical prognostic indices. This review highlights the current state of knowledge regarding risk stratification in FL.

Superior long-term outcome of patients with early transformation of non-Hodgkin lymphoma undergoing stem cell transplantation

In this study, we discuss the results of patients with transformed lymphoma (TL) undergoing stem cell transplantation (SCT). Because of the paucity of literature on the treatment of TL, deciding on the optimal evidence-based treatment is a challenge. Herein, our results indicate that patients with early transformation may benefit the most from SCT.

BACKGROUND

Transformed non-Hodgkin's lymphoma arising from follicular lymphoma (TL) carries a poor prognosis with a median survival time after transformation reported to be approximately 1 year.

PATIENTS AND METHODS

Fifty-one consecutive patients with TL received SCT between January 2000 and December 2010 (autologous SCT, n = 44, allogeneic SCT, n = 7).

RESULTS

Thirty-six (70.5%) patients had an early transformation, defined as histologic evidence of transformation at the time of initial diagnosis or transformation within 1 year of follicular lymphoma. Fifteen patients had early stage disease (29%) and 36 (71%) had advanced stage disease on presentation. At the time of analysis, 37 patients were alive with an estimated 5-year overall survival (OS) and event free survival (EFS) of 61.8% and 45%, respectively. OS and EFS were not significantly different between types of transplant procedure. The major cause of transplant failure was disease recurrence, with estimated 2-year relapse rate of 37.4%. Importantly, early transformation was independently associated with improved OS (hazard ratio [HR] 3.29; P = .028) and EFS (HR 2.49; P = .029).

CONCLUSION

Our results indicate that an aggressive transplant approach should be considered first in patients with TL and emphasize the need to incorporate novel strategies (eg, immunomodulation) early post-SCT to prevent relapses as disease recurrence remains the major cause of failure in heavily pretreated patients.

Non-Hodgkin lymphoma

Lymphomas are solid tumours of the immune system. Hodgkin's lymphoma accounts for about 10% of all lymphomas, and the remaining 90% are referred to as non-Hodgkin lymphoma. Non-Hodgkin lymphomas have a wide range of histological appearances and clinical features at presentation, which can make diagnosis difficult. Lymphomas are not rare, and most physicians, irrespective of their specialty, will probably have come across a patient with lymphoma. Timely diagnosis is important because effective, and often curative, therapies are available for many subtypes. In this Seminar we discuss advances in the understanding of the biology of these malignancies and new, available treatments.

High-dose therapy and autologous stem cell transplant for transformed non-Hodgkin lymphoma in the rituximab era

The impact of rituximab on the outcome of high-dose therapy and autologous stem cell transplant (HD-ASCT) for transformed non-Hodgkin lymphoma (NHL) has not been previously described. We analyzed 18 consecutive patients with indolent NHL who transformed to diffuse large B-cell lymphoma (DLBCL), received rituximab-containing therapy either before or after transformation and underwent subsequent HD-ASCT. With a median follow-up of 40 months, the 2-year progression-free survival (PFS) was 59% and the 2-year overall survival (OS) was 82%. Six patients did not receive rituximab pre-transformation. This group had a significantly better PFS at 2 years post-HD-ASCT compared to 12 patients who were exposed to rituximab pre-transformation (p = 0.03). HD-ASCT remains an effective therapeutic option for transformed NHL in the rituximab era. However, patients exposed to rituximab pre-transformation appear to have inferior HD-ASCT outcomes, and thus may benefit from novel conditioning and maintenance regimens in the setting of HD-ASCT.

Treatment options for transformed lymphoma: incorporating allogeneic stem cell transplantation in a multimodality approach

Transformed non-Hodgkin lymphoma (TL) arising from follicular lymphoma carries a poor prognosis, and the median survival time after transformation is approximately 10 to 12 months. Standard chemotherapy and radioimmunotherapy have offered promising responses; however, the duration of response does not appear to last long. Several studies evaluating the role of autologous stem cell transplantation (auto-SCT) as a salvage regimen have been reported, and a subset of patients benefit from this modality of treatment. With an improvement in supportive care, outcome after allogeneic stem cell transplantation (allo-SCT) has been improved significantly over past decades; however, very limited data are available for TL. In the era of emerging novel therapies, the actual timing, optimal conditioning regimens, and long-term impact of the type of stem cell transplantation (auto-SCT vs allo-SCT) is unclear. This review addresses the approaches to the management of patients with TL.

Enzastaurin hydrochloride for lymphoma: reassessing the results of clinical trials in light of recent advances in the biology of B-cell malignancies

INTRODUCTION

The B-cell receptor (BCR) is critical for the development and persistence of B-cell non-Hodgkin lymphoma (B-NHL). Protein kinase C-beta (PKC-?) has been identified as one of the key signaling hubs downstream of the BCR and constitutes a valuable target in B-NHL. As a potent PKC-? inhibitor, enzastaurin is currently being tested in Phase II/III trials.

AREAS COVERED

This review summarizes the latest results and ongoing clinical trials with enzastaurin in light of basic scientific advances in the understanding of various lymphoid cancers, including diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma (MCL), follicular lymphoma (FL), chronic lymphocytic leukemia (CLL) and Waldenstr?m's macroglobulinemia (WM).

EXPERT OPINION

While its continued clinical development is uncertain, enzastaurin should be regarded as a stepping stone for the development of future therapies; indeed, the recent research has provided valuable insight into the possible molecular mechanisms that explain its limited clinical activity especially in the treatment of DLBCL and MCL. It should be noted that there is still some interest in enzastaurin, in combination, for the treatment of WM.

Transformation of Indolent B-Cell Lymphomas

Histologic transformation (HT) to an aggressive lymphoma is a well-described event in the natural history and clinical course of patients with so-called indolent lymphomas. This phenomenon has been studied most extensively in patients with follicular lymphoma and subsequent transformation to a diffuse large B-cell lymphoma, with little literature on HT in nonfollicular lymphomas. Despite a considerable body of information on the pathologic and molecular events associated with HT, its pathogenesis has remained elusive and the molecular information available has not been translated into clinical advances. It remains unclear if there is already a predisposition to HT and whether this can be detected at the time of diagnosis. The rituximab era has been characterized by a significant improvement in the prognosis of patients with B-cell lymphomas, but HT remains one of the most important challenges in the management of patients with indolent lymphoma, the difficulties starting with the diagnosis and definition of HT and ending with the appropriate management and treatment of the event. Going forward, it is crucial to incorporate HT as a major end point in clinical trials and to include patients with HT as subject of such studies if we are to see meaningful progress in the future.

Genomic alterations reveal potential for higher grade transformation in follicular lymphoma and confirm parallel evolution of tumor cell clones

Our aim was to examine the genetics of clonal evolution in follicular lymphoma (FL) and to identify genetic alterations associated with disease progression. A total of 100 biopsies from 44 patients diagnosed with t(14;18)-positive FL were examined by array comparative genomic hybridization. In 20 patients the patterns of somatic hypermutations (SHMs) in the variable region of heavy chain gene were additionally analyzed. Gain of chromosome X in male samples was a marker for poor outcome (P < .01). Gains involving chromosome 2, 3q, and 5 were exclusively present in FL biopsies from cases with higher grade transformation and were among the copy number alterations (CNAs) associated with inferior survival. Although we noted a trend for increasing genomic complexity in initial versus late FL samples, the overall frequencies of CNAs in initial and late FL biopsies showed a surprisingly stable pattern through the course of the disease. In 27 of cases the initial samples harbored CNAs that were absent in relapse samples, indicating that tumor cell clones at relapse were not direct descendants of initially dominating clones. The pattern of SHMs confirmed parallel development of tumor cell clones in 14 cases. Our findings support the hypothesis of common progenitor cells in FL.