Yttrium-90 ibritumomab tiuxetan radioimmunotherapy in Richter syndrome

Treatment of Richter Transformation of Chronic Lymphocytic Leukemia in the Modern Era

Richter Transformation (RT) refers to the development of an aggressive lymphoma in the setting of chronic lymphocytic leukemia (CLL). While many variants of RT are recognized, diffuse large B-cell lymphoma (RT-DLBCL) is the most common (80%), followed by Hodgkin’s lymphoma (RT-HL, 19%). Diagnosis is based upon histologic evaluation of clinically suspicious lymph nodes. Positron emission tomography (PET) may be used to select the node of interest for biopsy. Although clonality testing is not a prerequisite of RT diagnosis, it has significant implications for survival. Clonally related DLBCL carries the worst prognosis with a median overall survival (OS) of less than one year in the era of combination chemotherapies with or without anti-CD20 antibodies. Prognosis has improved with the use of stem cell transplant and newer agents such as targeted therapy and newer forms of immunotherapy. Consideration of a clinical trial is encouraged. This review describes our current understanding of RT and focuses on treatment of RT-DLBCL, including clinical trials in progress and new therapies in development. We also report an illustrative example of a patient with clonally related DLBCL who survived two years after diagnosis without the use of combination chemotherapy.

Richter Syndrome

PURPOSE OF REVIEW

Richter syndrome (RS) is an uncommon but aggressive evolution of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). RS is an unmet clinical need in the field of CLL. Recent advances in understanding the biology of this condition provide the rationale for testing new therapeutic concepts in order to improve the outcome of patients developing RS, which is so far poor. In this review, we summarize disease characteristics and available therapeutic options for RS.

RECENT FINDINGS

Current regimens with novel agents in monotherapy have shown little impact on survival. Nevertheless, the better reported outcome for RS has been achieved with the combination of chemo-immunotherapy with a novel agent, confirming the synergistic effect of the approaches. Still, the frailty of this population may impose a less toxic management leaving most patients with no reasonable therapeutic option. Treatment options for RS need to be further expanded. Preclinical models in current development may allow to explore actionable pathways and identify new drug targeted combinations.

Allogeneic hematopoietic cell transplantation is an effective treatment for patients with Richter syndrome: A systematic review and meta-analysis

Efficacy of conventional chemoimmunotherapy is limited in patients with Richter syndrome (RS) with anticipated median overall survival (OS) of less than 10 months. Allogeneic hematopoietic cell transplantation (allo-HCT) is commonly offered as a consolidative treatment option in RS. To our knowledge, there are no randomized controlled studies that have compared allo-HCT against other therapies in RS; available allo-HCT data are limited to small case series from single-institution or registry studies. We performed a systematic review and meta-analysis to assess the totality of evidence regarding the efficacy (or lack thereof) of allo-HCT for RS. We extracted data on post-allograft outcomes related to benefits (overall response rate [ORR], complete remission [CR], OS, and progression-free survival [PFS]). For harms, data were extracted on non-relapse mortality (NRM) and relapse post-allografting. Our search strategy identified 240 studies, but only four studies (n = 72 patients) met our inclusion criteria. Pooled ORR, CR, OS, and PFS rates were 79%, 33%, 49%, and 30%, respectively. Pooled NRM and relapse rates were 24% and 28%, respectively. Results of this systematic review and meta-analysis indicate that allo-HCT yields encouraging OS in RS, thus remaining a reasonable treatment option in fit patients whose disease demonstrates a chemosensitive response to pre-transplant salvage therapies. Novel strategies are certainly needed to reduce the risk of relapse to further improve outcomes in these patients.

Successful Treatment of Richter Transformation with Ibrutinib in a Patient with Chronic Lymphocytic Leukemia following Allogeneic Hematopoietic Stem Cell Transplant

Patients with chronic lymphocytic leukemia (CLL) who progress to Richter transformation (RT) have a poor prognosis. Multi-agent chemotherapy regimens do not have good response rates. There are few case reports on the use of ibrutinib in RT. Here, we present a patient who was heavily pretreated for CLL, including allogeneic stem cell transplant, and progressed to RT. She had a mixed response to multi-agent chemotherapy and was started on ibrutinib. She had a complete response for 16 months on single-agent ibrutinib with minimal toxicity.

Richter Syndrome in Chronic Lymphocytic Leukemia

The term Richter syndrome (RS) indicates the transformation of chronic lymphocytic leukemia (CLL) into an aggressive lymphoma. RS is a rare complication with an aggressive clinical course, bearing an unfavorable prognosis. In the majority of cases, CLL transforms into RS as diffuse large B cell lymphoma (DLBCL), and a clonal relation between the two processes can be found. However, clonally unrelated RS can occur and transformations to other histologies beside DLBCL have been described. Recent data have shed some light on genetic characteristics that can influence and drive the transformation from CLL to RS. This molecular information has not been translated yet into significant treatment advances, and currently the therapy regimens for RS continue to rely on intensive chemotherapy combinations followed by stem cell transplant in suitable candidates. Based on the rapid pace of discoveries in the field of hematological malignancies and on the recent revolution in the therapeutic landscape for CLL and B cell lymphomas, new therapeutic options for RS might be available in the upcoming years.

Richter syndrome: pathogenesis and management

Richter syndrome (RS) is the development of an aggressive lymphoma in patients with a previous or concomitant diagnosis of chronic lymphocytic leukemia (CLL). The incidence rate RS is ~0.5% per year of observation. Two biomarkers (NOTCH1 mutations and subset 8 configuration of the B-cell receptor) may help identifying CLL patients at risk of RS to be considered for close monitoring and a careful biopsy policy. In the presence of clinical features suspicious of RS, diagnosis of transformation and choice of the site of biopsy may take advantage of fluorine 18 fluorodeoxyglucose ((18)FDG) positron emission tomography (PET)/computed tomography (CT). Molecular lesions of regulators of tumor suppression (TP53), cell cycle (CDKN2A), and cell proliferation (NOTCH1, MYC) overall account for ~90% of RS and may be responsible for the aggressive clinical phenotype observed in this disease because of the combined effect of chemoresistance and rapid disease kinetics. The prognosis of RS is generally highly unfavorable. However, the pattern of survival is not homogeneous and the most important prognostic factor is the clonal relationship between the CLL and the aggressive lymphoma clones. Rituximab-containing polychemotherapy represents the backbone for induction treatment in RS. Younger patients who respond to induction therapy should be offered stem cell transplant (SCT) to prolong survival.

Richter syndrome in chronic lymphocytic leukemia: updates on biology, clinical features and therapy

Richter syndrome (RS) or Richter transformation is the development of secondary aggressive lymphoma in the setting of underlying chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Most frequently CLL transforms into diffuse large B-cell lymphoma (DLBCL) (90%) and rarely (10%) into Hodgkin lymphoma, termed Hodgkin variant of Richter syndrome (HvRS). RS is generally characterized by an aggressive clinical course and poor prognosis. In recent years, major advances have been made in understanding genetic events which relate to the progression of CLL or transformation into RS. Better understanding of the molecular pathways has revealed that RS is not a single homogeneous entity. The majority of cases are clonally related to the original CLL clone, while a minority develop from an unrelated clone. This review summarizes new data relating to the molecular biology and the genetic/epigenetic changes occurring during Richter transformation, and also considers the clinical features and therapy for both DLBCL-RS and Hodgkin variant-RS.

How we treat Richter syndrome

Richter syndrome (RS) is defined as the transformation of chronic lymphocytic leukemia (CLL) into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). RS occurs in approximately 2% to 10% of CLL patients during the course of their disease, with a transformation rate of 0.5% to 1% per year. A combination of germline genetic characteristics, clinical features (eg, advanced Rai stage), biologic (ζ-associated protein-70(+), CD38(+), CD49d(+)) and somatic genetic (del17p13.1 or del11q23.1) characteristics of CLL B cells, and certain CLL therapies are associated with higher risk of RS. Recent studies have also identified the crucial role of CDKN2A loss, TP53 disruption, C-MYC activation, and NOTCH1 mutations in the transformation from CLL to RS. An excisional lymph node biopsy is considered the gold standard for diagnosis of RS; a (18)F-fluorodeoxyglucose positron emission tomography scan can help inform the optimal site for biopsy. Approximately 80% of DLBCL cases in patients with CLL are clonally related to the underlying CLL, and the median survival for these patients is approximately 1 year. In contrast, the remaining 20% of patients have a clonally unrelated DLBCL and have a prognosis similar to that of de novo DLBCL. For patients with clonally related DLBCL, induction therapy with either an anthracycline- or platinum-based regimen is the standard approach. Postremission stem cell transplantation should be considered for appropriate patients. This article summarizes our approach to the clinical management of CLL patients who develop RS.

Second Malignancies and Richter's Syndrome in Patients with Chronic Lymphocytic Leukemia

Second malignancies are frequent complications in patients with chronic lymphocytic leukemia (CLL). Patients with this leukemia may develop large cell lymphoma (LCL) known as Richter's syndrome (RS). RS occurs in CLL patients of about 3% and may develop in a single lymph node or more often in a group of nodes. However, in some patients extranodal localization of aggressive lymphoma in RS has been observed. Besides LCL, Hodgkin's disease, prolymphocytoid leukemia, multiple myeloma and acute lymphoblastic leukemia may also occur as RS variants. The origin of lymphoid cells in RS remains tentative. However, CLL and RS originate from the same clone for some patients, whereas, in other patients cells of aggressive lymphoma do not have the features of the same clone as the CLL cells. The prognosis of RS is poor. Survival in different studies will be usually 2-5 months. The secondary development or coexistence of myeloproliferative disorders or myelodysplastic syndrome and solid tumors have also been rarely documented in CLL patients. It is of great concern that therapy may further increase the risk of a second neoplasm. However, until now, there are no clear evidence that alkylating agents or purine nucleoside analogs may be associated with an increased incidence of second malignancies in patients with CLL. In this review, epidemiology, biology, clinical characteristic and treatment approaches in RS and other secondary neoplasms in patients with CLL are discussed.

Richter syndrome

Transformation of chronic lymphocytic leukemia (CLL) to aggressive lymphoma is known as Richter syndrome (RS). In the CLL population considered as a whole, the prevalence of RS development ranges from 2 to 7 %. The most common pathologic phenotype at the time of RS transformation is diffuse large B-cell lymphoma (DLBCL), while, in a small fraction of cases, the transformed phase shows pathologic features mimicking Hodgkin lymphoma. TP53 disruption and MYC activation cooperate as dual hits in driving DLBCL transformation. Two biomarkers (NOTCH1 mutations and usage of the immunoglobulin VH CDR3 subset 8) may help in identifying CLL patients at risk of DLBCL transformation to be considered for close monitoring and a careful biopsy policy. In the presence of clinical features suspicious of RS, diagnosis of transformation and choice of the site of biopsy may take advantage of (18)FDG PET/CT. The prognosis of RS transformation is generally highly unfavorable. However, the pattern of survival is not homogeneous and may be predicted on clinical and biological grounds. RS that are clonally unrelated to the paired CLL phase are biologically and clinically different from clonally related cases, and should be considered, and probably managed, as a de novo DLBCL arising in the context of CLL. Rituximab-containing polychemotherapy represents the backbone for induction treatment in patients with clonally related DLBCL transformation. Younger patients who respond to induction therapy should be offered stem cell transplant to prolong survival.

Cancer immunotherapy

Cancer immunotherapy consists of approaches that modify the host immune system, and/or the utilization of components of the immune system, as cancer treatment. During the past 25 years, 17 immunologic products have received regulatory approval based on anticancer activity as single agents and/or in combination with chemotherapy. These include the nonspecific immune stimulants BCG and levamisole; the cytokines interferon-α and interleukin-2; the monoclonal antibodies rituximab, ofatumumab, alemtuzumab, trastuzumab, bevacizumab, cetuximab, and panitumumab; the radiolabeled antibodies Y-90 ibritumomab tiuxetan and I-131 tositumomab; the immunotoxins denileukin diftitox and gemtuzumab ozogamicin; nonmyeloablative allogeneic transplants with donor lymphocyte infusions; and the anti-prostate cancer cell-based therapy sipuleucel-T. All but two of these products are still regularly used to treat various B- and T-cell malignancies, and numerous solid tumors, including breast, lung, colorectal, prostate, melanoma, kidney, glioblastoma, bladder, and head and neck. Positive randomized trials have recently been reported for idiotype vaccines in lymphoma and a peptide vaccine in melanoma. The anti-CTLA-4 monoclonal antibody ipilumumab, which blocks regulatory T-cells, is expected to receive regulatory approval in the near future, based on a randomized trial in melanoma. As the fourth modality of cancer treatment, biotherapy/immunotherapy is an increasingly important component of the anticancer armamentarium.

A systematic review on Richter syndrome: what is the published evidence?

A systematic and comprehensive search of literature was performed using MEDLINE databases from 1st January 1978 to 2nd November 2009 and hand search of references. A search performed by combining the Medical Subject Headings (MESH) terms 'Richter's syndrome' and 'chronic lymphocytic leukemia' (CLL) yielded 143 citations. Ten additional case-control studies judged relevant for the purpose of study were also included. In total, 45 case reports, 18 case series, and 9 case-control studies were identified. For the purpose of this review, only case series and case-control studies were considered. The following conclusions could be drawn from the studies analyzed in this review: (i) some biological markers (i.e. CD38 expression and genotype, absence of del13q) or clinical features (i.e. bulky lymph node involvement), although not validated in prospective trials, may be considered for close monitoring and a careful biopsy policy; (ii) PET, is not yet standardized in RS, however, it may be useful in the diagnosis and to choose the site for biopsy; (iii) when diagnosed RS should be treated with a combination of rituximab and polychemotherapy; (iii) younger patients who respond to initial therapy should be offered allogeneic SCT, if feasible. Despite the paucity of data, it is important to note that this article represents the first systematic review of the entire body of available clinical evidence useful for an appropriate management of Richter transformation.

Yttrium 90 ibritumomab tiuxetan in lymphoma

Radioimmunoconjugates are radioisotope-bound monoclonal antibodies that target radiation specifically to sites of lymphoma involvement. Initial studies of 90Y-ibritumomab tiuxetan in non-Hodgkin's lymphoma (NHL) have suggested benefit in patients with relapsed or refractory indolent disease. However, the routine adoption of this agent is tempered by concerns of associated toxicities and unclear long-term benefit. A comprehensive search for studies on 90Y-ibritumomab tiuxetan use in lymphoma was completed. The aims of this systematic review were to summarize and evaluate the evidence on: (1) the benefits and risks of this novel therapy; (2) predictors for response and toxicity; and (3) the role of dosimetry and imaging studies prior to treatment. A total of twenty trials investigating the use of 90Y-ibritumomab tiuxetan for the treatment of adult patients with NHL were identified. In trials of patients with relapsed or refractory indolent NHL, overall response rates ranged from 67 - 83%. In patients with follicular NHL refractory to the monoclonal antibody, rituximab, response rates remained high (74%). However, in rituximab-naïve patients with relapsed or refractory indolent or transformed NHL, the higher response rate seen with 90Y-ibritumomab tiuxetan therapy compared to rituximab monotherapy has not translated into clear improvements in time-to-progression or survival. 90Y-ibritumomab tiuxetan is an active agent in relapsed and refractory non-Hodgkin's lymphoma that should be considered in select patients.

Richter syndrome: molecular insights and clinical perspectives

Richter syndrome (RS) represents the clinico-pathologic transformation of chronic lymphocytic leukaemia (CLL) to an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). The clinical definition of RS is heterogeneous, and encompasses at least two biologically different conditions: (i) CLL transformation to a clonally related DLBCL, that accounts for the majority of cases; (ii) development of a DLBCL unrelated to the CLL clone. In clonally related RS, the pathogenetic link between the CLL and the DLBCL phases is substantiated by the acquisition of novel molecular lesions at the time of clinico-pathologic transformation. RS is not a rare event in the natural history of CLL, since the cumulative incidence of RS at 10 years exceeds 10%. Prompt recognition of RS is known to be clinically useful, and may be favoured by close monitoring of CLL patients harbouring clinical and/or biological risk factors of RS development. Conventional risk factors that are independent predictors of RS development at the time of CLL diagnosis include: (i) expression of CD38; (ii) absence of del13q14 and (iii) lymph node size > or =3 cm. Other risk factors of RS development include CD38 genotype and usage of specific immunoglobulin variable genes. The molecular pathogenesis of RS has been elucidated to a certain extent. Acquisition of TP53 mutations and/or 17p13 deletion is a frequent molecular event in RS, as it is in other types of transformation from indolent to aggressive B-cell malignancies. Additional molecular alterations are being revealed by genome wide studies. Once that transformation has occurred, RS prognosis may be predicted by the RS score, based on performance status, LDH, platelet count, tumour size and number of prior therapies. Depending on patient's age and RS score, the therapeutic options for RS may range from conventional immunochemotherapy to allogeneic bone marrow transplantation.

Recent advances in the diagnosis and therapy of richter’s syndrome

Richter's syndrome (RS) denotes the development of aggressive lymphoma that arises in patients with chronic lymphocytic leukemia (CLL). Presenting features typically include a rapid clinical deterioration with fever in the absence of infection, progressive lymph node enlargement, and an elevation in serum LDH. Diagnostic biopsy of affected sites usually reveals large cell lymphomas; however, Hodgkin variant cases have been described. Richter's transformation occurs in approx 5% of CLL patients and may be associated with infection with Epstein-Barr virus (EBV). Chromosome 11 and 14 abnormalities have also been described as well as tumor suppressor gene defects involving p53, p21, and p27. Treatment options for these patients are limited and include combination chemotherapy with or without the addition of monoclonal antibodies and stem cell transplantation. Response to therapy is variable and generally short-lived. Median survival is usually in the order of 5-8 mo. More effective management for RS is needed as well as prognostic models that will identify CLL patients at risk of transformation. This review will address the current status of RS and deal with the pathophysiology, diagnostic approach, and treatment of this challenging disease.

Is targeted chemotherapy an alternative to immunotherapy in chronic lymphocytic leukemia?

Although molecular remission is now detected, it is still unknown whether we have the tools to cure B cell chronic lymphocytic leukemia (referred to as CLL). Nonetheless, several new therapeutic approaches have been introduced in cancer therapy during the last decade, including antiangiogenic therapy, apoptosis-inducing treatment and inhibition of heat shock proteins, farnesyl transferase, tyrosine kinases and proteasomes. These modalities may also be considered in CLL, but additional experimental characterization is required. Further characterization and development of CLL animal models should be a part of this preclinical work (especially xenografting in NOD/SCID animals, but also murine leukemia) to allow a more extensive evaluation prior to clinical trials. Animal models are particularly important for preclinical comparison of pharmacological effects between different disease compartments and for in vivo evaluation of antileukemic immune reactivity. However, T cell targeting therapy seems to have several advantages in comparison to other approaches: (1) based on the current clinical experience one would expect low toxicity for several of these strategies, especially vaccine treatment; (2) several studies have demonstrated that autologous T cells can recognize CLL cells; (3) experimental and clinical evidence suggests that immunotherapy can be combined with chemotherapy. Thus, T cell therapy has a relatively strong scientific basis that justifies further clinical studies of immunotherapy in CLL. Although several of the new pharmacological agents seem to have immunosuppressive effects, at least some of them (e.g. heat shock protein 90 inhibitors, proteasome inhibitors, inhibition of angiogenesis) appear to affect T cells only at relatively high concentrations and may thus be used in combination with immunotherapy.

Richterʼs Syndrome

Richter's syndrome, that is, transformation of chronic lymphocytic leukemia to a large cell or immunoblastic lymphoma, occurs in up to 10% of patients with chronic lymphocytic leukemia. The onset of Richter's syndrome is characterized by worsening systemic symptoms, rapid tumor growth, and/or extranodal involvement. Median survival with conventional chemotherapy is less than 6 months. Therapy with more recent therapeutic regimens, such as hyperCVXD (fractionated cyclophosphamide, vincristine, liposomal daunorubicin, and dexamethasone), augmented hyperCVXD, and yttrium-90 ibritumomab tiuxetan, has not produced major improvements in response rates or overall survival. Improvement in the outcome of patients with Richter's syndrome may be aided by a more comprehensive understanding of the pathogenesis of Richter's syndrome; therapy could then be targeted against specific abnormalities. Current data indicate that the transformation of chronic lymphocytic leukemia to a large-cell or immunoblastic lymphoma is associated with abnormalities in cell cycle regulation (e.g., loss of the cell cycle inhibitors p16(INK4a) and p27(KIP1) ) and DNA repair (e.g., mutations and/or deletions of the p53, ATM, and p14(ARF) genes and epigenetic silencing of the MLH1 gene). However, the critical event leading to transformation is unclear. Given the poor prognosis of patients with Richter's syndrome, every effort should be made to enroll these patients into clinical trials evaluating novel agents with the appropriate correlative studies.

Richter syndrome: biology, incidence, and therapeutic strategies

Richter's transformation denotes the development of high-grade non-Hodgkin lymphoma, prolymphocytic leukemia, Hodgkin disease, or acute leukemia in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma. A search of published articles in Medline (PubMed) and abstracts from professional meetings was performed. An electronic database search of patients with CLL at The University of Texas M. D. Anderson Cancer Center (Houston, TX) determined the incidence of Richter syndrome (RS) in patients with CLL between 1992 and 2002. RS occurs in approximately 5% of patients with CLL. The large cells of RS may arise through transformation of the original CLL clone or represent a new neoplasm. RS may be triggered by viral infections, such as Epstein-Barr virus. Trisomy 12 and chromosome 11 abnormalities are more frequent in patients with RS than in the overall population of patients with CLL. Multiple genetic defects, such as mutations of the p53 tumor suppressor gene, p16INK4A, and p21, loss of p27 expression, deletion of retinoblastoma, increased copy number of C-MYC, and decreased expression of the A-MYB gene, have been described. These abnormalities may cause CLL cells to proliferate and-by facilitating the acquisition of new genetic abnormalities-to transform into RS cells. Therapeutic strategies include intensive chemotherapy, monoclonal antibodies, and stem cell transplantation. The response rates range from 5% to 43% (complete response, 5-38%), and the median survival duration ranges from 5 months to 8 months. In conclusion, RS may be triggered by viral infections or by genetic defects. Current treatments are aggressive, but prognosis is poor. Novel curative treatment strategies are needed.