Immunotherapy in mantle cell lymphoma: anti-CD20-based therapy and beyond

Survival Trends in Patients Under Age 65 Years With Mantle Cell Lymphoma, 1995-2016: A SEER-Based Analysis

Purpose: The treatment paradigm for mantle cell lymphoma (MCL), a B-cell malignancy, has shifted considerably during the past decades. This study aimed to evaluate time trends in overall survival (OS) and disease-specific mortality (DSM) of younger (age ≤ 65 years) patients with MCL from 1995 to 2016.

Methods: We used the Surveillance, Epidemiology, and End Results database. Year of diagnosis was divided into three eras: the chemotherapy-alone era (1995–2000), intensified-immunochemotherapy era (2001–2012), and targeted-therapy era (2013–2016). We used the Kaplan–Meier method, log-rank test, and subdistribution proportional hazard regression in the analysis.

Results: A total 4,892 patients were identified. Median OS increased from 67 months in the chemotherapy-alone era to 107 months in the intensified-immunochemotherapy era (P < 0.001). The DSM rate decreased significantly from 1995 to 2016 (P < 0.001); the adjusted hazard ratios of MCL-specific death were 0.589 (P < 0.001) for the intensified-immunochemotherapy era and 0.459 (P < 0.001) for targeted-therapy era, as compared with the chemotherapy-alone era. Patients with advanced-stage MCL exhibited lowering risk of death across the three eras (P < 0.001).

Conclusions: During 1995–2016, survival in younger patients with MCL increased significantly, especially those with advanced-stage disease, potentially reflecting the impact of advancement in treatment modalities on MCL outcome.

Vaccination strategies in lymphoproliferative disorders: Failures and successes

Anti-tumor vaccines in lymphoproliferative disorders hold out the prospect of effective tumor therapies with minimal side effects. The addition of immunotherapy to old and new chemotherapy regimens has improved both response rates and disease-free survival, leading in many cases to an extended overall survival. Ideally, an antigen that is used for vaccination would be specifically expressed in the tumor; it must have an important, causal part in the multifactorial process that leads to cancer, and it must be expressed stably even after it is attacked by the immune system. Immunotherapies, which aim to activate the immune system to kill cancer cells, include strategies to increase the frequency or potency of antitumor T cells, to overcome suppressive factors in the tumor microenvironment, and to reduce T-cell suppression systemically. In this review, we focus on the results of clinical trials of vaccination in lymphoma, and discuss potential strategies to enhance the efficacy of immunotherapy in the future.

In vitro and in vivo therapeutic efficacy of carfilzomib in mantle cell lymphoma: targeting the immunoproteasome

Mantle cell lymphoma (MCL) remains incurable due to its inevitable pattern of relapse after treatment with current existing therapies. However, the promise of a cure for MCL lies in the burgeoning area of novel agents. In this study, we elucidated the therapeutic effect and mechanism of carfilzomib, a novel long-acting second-generation proteasome inhibitor, in MCL cells. We found that carfilzomib induced growth inhibition and apoptosis in both established MCL cell lines and freshly isolated primary MCL cells in a dose-dependent manner. In contrast, carfilzomib was less toxic to normal peripheral blood mononuclear cells from healthy individuals. The carfilzomib-induced apoptosis of MCL cells was mediated by the activation of JNK, Bcl-2, and mitochondria-related pathways. In addition, carfilzomib inhibited the growth and survival signaling pathways NF-κB and STAT3. Interestingly, we discovered that expression of immunoproteasome (i-proteasome) subunits is required for the anti-MCL activity of carfilzomib in MCL cells. In MCL-bearing SCID mice/primary MCL-bearing SCID-hu mice, intravenous administration of 5 mg/kg carfilzomib on days 1 and 2 for 5 weeks slowed/abrogated tumor growth and significantly prolonged survival. Our preclinical data show that carfilzomib is a promising, potentially less toxic treatment for MCL. Furthermore, an intact i-proteasome, especially LMP2, appears to be necessary for its anti-MCL activity, suggesting that i-proteasome could serve as a biomarker for identifying patients who will benefit from carfilzomib.

Therapeutic effects of thalidomide in hematologic disorders: a review

The extensive autoimmune, anti-inflammatory, and anticancer applications of thalidomide have inspired a growing number of studies and clinical trials. As an inexpensive agent with relatively low toxicity, thalidomide is regarded as a promising therapeutic candidate, especially for malignant diseases. We review its therapeutic effects in hematology, including those on multiple myeloma, Waldenstroem macroglobulinemia, lymphoma, mantle-cell lymphoma, myelodysplastic syndrome, hereditary hemorrhagic telangiectasia, and graftversus-host disease. Most studies have shown satisfactory results, although several have reported the opposite. Aside from optimal outcomes, the toxicities and adverse effects of thalidomide should also be examined. The current work includes a discussion of the mechanisms through which the novel biological effects of thalidomide occur, although more studies should be devoted to this aspect. With appropriate safeguards, thalidomide may benefit patients suffering from a broad variety of disorders, particularly refractory and resistant diseases.

Selective immunophenotyping for diagnosis of B-cell neoplasms: immunohistochemistry and flow cytometry strategies and results

Determining the immunophenotype of hematologic malignancies is now an indispensable part of diagnostic classification, and can help to guide therapy, or to predict clinical outcome. Diagnostic workup should be guided by morphologic findings and evaluate clinically important markers, but ideally should avoid the use of overly broad panels of immunostains that can reveal incidental findings of uncertain significance and give rise to increased costs. Here, we outline our approach to diagnosis of B-cell neoplasms, combining histologic and clinical data with tailored panels of immunophenotyping reagents, in the context of the 2008 World Health Organization classification. We present data from cases seen at our institution from 2004 through 2008 using this approach, to provide a practical reference for findings seen in daily diagnostic practice.

Stat3 inhibition augments the immunogenicity of B-cell lymphoma cells, leading to effective antitumor immunity

Mantle cell lymphoma (MCL) is an aggressive and incurable subtype of B-cell non-Hodgkin lymphomas. Although patients often respond initially to first-line treatment with chemotherapy plus monoclonal antibodies, relapse and decreased response to further lines of treatment eventually occurs. Harnessing the immune system to elicit its exquisite specificity and long-lasting protection might provide sustained MCL immunity that could potentially eradicate residual malignant cells responsible for disease relapse. Here, we show that genetic or pharmacologic disruption of Stat3 in malignant B cells augments their immunogenicity leading to better activation of antigen-specific CD4(+) T cells and restoration of responsiveness of tolerized T cells. In addition, treatment of MCL-bearing mice with a specific Stat3 inhibitor resulted in decreased Stat3 phosphorylation in malignant B cells and anti-lymphoma immunity in vivo. Our findings therefore indicate that Stat3 inhibition may represent a therapeutic strategy to overcome tolerance to tumor antigens and elicit a strong immunity against MCL and other B-cell malignancies.

Survival trends in mantle cell lymphoma in the United States over 16 years 1992-2007

A retrospective analysis was done using the Surveillance, Epidemiology, and End-Results (SEER) database to determine the trends in overall survival and identify prognostic factors in patients with mantle cell lymphoma (MCL). In total 5367 cases of MCL identified from 1992 to 2007 were split into three cohorts, group 1(1992-1999), group 2 (2000-2003) and group 3 (2004-2007). Survival was analyzed using the Cox proportional hazards model to correct for age, gender and stage of disease. The proportion of patients with advanced disease at diagnosis, male gender and advanced age increased over time and these were all associated with increased mortality. The overall survival remained unchanged. However, when adjusted for the increased proportion of patients with poor prognostic features noted above, we found a significant improvement in survival. The adjusted model also showed an improvement in predicted survival over time in patients with advanced stage. No change in survival was seen in patients with localized disease. Although this analysis is not designed to evaluate specific treatment modalities, these data suggest that the development of new treatment strategies over the past decade may be impacting the survival of patients with advanced MCL despite the finding that the overall survival remains unchanged in the general US population.

Novel targeted therapies for mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive B-cell malignancy characterized by short median survival despite intensive therapies. The clinical behavior of MCL may be due to the complex pathophysiology of the disease which includes its genetic hallmark, the chromosomal translocation t(11;14) resulting in aberrant expression of cyclin D1, alteration in the DNA damage response, and constitutive activation of key anti-apoptotic pathways such as phosphatidyl-inositol 3-kinase (PI3K)/Akt and nuclear factor-kB (NF-kB). Collectively, these changes result in cell cycle dysregulation and give rise to profound genetic instability. Given this complex pathophysiology, the limited number of options for patients with relapsed/refractory MCL, and the difficulty in achieving long-lasting remissions with conventional approaches, it is essential to explore new treatment options targeting the numerous dysregulated pathways that are operable in MCL. We have recently reported that milatuzumab, a fully humanized anti-CD74 monoclonal antibody (mAb), in combination with anti-CD20 mAbs has significant preclinical and clinical activity in MCL. Here we discuss these results, provide additional insights into milatuzumab-mediated MCL cell death, and report preliminary data on the activity of other targeted biologic agents including PCI-32765 and CAL-101 currently undergoing evaluation at our institution and others.

Combination anti-CD74 (milatuzumab) and anti-CD20 (rituximab) monoclonal antibody therapy has in vitro and in vivo activity in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive B-cell malignancy with a median survival of 3 years despite chemoimmunotherapy. Rituximab, a chimeric anti-CD20 monoclonal antibody (mAb), has shown only modest activity as single agent in MCL. The humanized mAb milatuzumab targets CD74, an integral membrane protein linked with promotion of B-cell growth and survival, and has shown preclinical activity against B-cell malignancies. Because rituximab and milatuzumab target distinct antigens and potentially signal through different pathways, we explored a preclinical combination strategy in MCL. Treatment of MCL cell lines and primary tumor cells with immobilized milatuzumab and rituximab resulted in rapid cell death, radical oxygen species generation, and loss of mitochondrial membrane potential. Cytoskeletal distrupting agents significantly reduced formation of CD20/CD74 aggregates, cell adhesion, and cell death, highlighting the importance of actin microfilaments in rituximab/milatuzumab-mediated cell death. Cell death was independent of caspase activation, Bcl-2 family proteins or modulation of autophagy. Maximal inhibition of p65 nuclear translocation was observed with combination treatment, indicating disruption of the NF-κB pathway. Significant in vivo therapeutic activity of combination rituximab and milatuzumab was demonstrated in a preclinical model of MCL. These data support clinical evaluation of combination milatuzumab and rituximab therapy in MCL.

Temsirolimus for the treatment of mantle cell lymphoma

Although recent progress has been made in the treatment of mantle cell lymphoma (MCL) the majority of patients experience relapse and ultimately die of their disease. The translocation t(11;14) is a prerequisite for the diagnosis of MCL and results in overexpression of cyclin D1. Its protein translation is controlled by mTOR, a key element of the PI3K/Akt pathway, and mTOR constitutes an attractive therapeutic target. Temsirolimus, a specific inhibitor of mTOR, has been evaluated in two Phase II trials in patients with relapsed MCL, and promising response rates up to 40% were found. Subsequently, a randomized Phase III trial was initiated, in which superiority in remission induction and progression-free survival could be demonstrated for a regimen of temsirolimus 175 mg for 3 weeks, followed by a 75-mg weekly application in comparison with established agents. This adds temsirolimus to the therapeutic armamentarium for the treatment of MCL. Further developments target combination therapy in MCL and other lymphoid neoplasms.

Synergistic antitumor effects of lenalidomide and rituximab on mantle cell lymphoma in vitro and in vivo

Rituximab (RTX), a chimeric anti-CD20 antibody, is associated with direct induction of apoptosis and antibody-dependent cell-mediated cytotoxicity (ADCC) with clinical efficacy in mantle cell lymphoma (MCL). Lenalidomide (LEN), a novel immunomodulatory agent, sensitizes tumor cells and enhances ADCC. Our study attempted to elucidate the mechanism of LEN-enhanced RTX-mediated cytotoxicity of MCL cells. We found that LEN and RTX induced growth inhibition of both cultured and fresh primary MCL cells. LEN enhanced RTX-induced apoptosis via upregulating phosphorylation of c-Jun N-terminal protein kinases (JNK), Bcl-2, Bad; increasing release of cytochrome-c; enhancing activation of caspase-3, -8, -9 and cleavage of PARP. Meanwhile, LEN activated NK cells and increased CD16 expression on CD56(low)CD16(+) NK cells. Whole PBMCs but not NK cell-depleted PBMCs treated with LEN augmented 30% of RTX-dependent cytotoxicity. Daily treatment with LEN increased NK cells by 10-folds in SCID mice, and combination of LEN and RTX decreased tumor burden and prolonged survival of MCL-bearing SCID mice. Taken together, our study demonstrates that LEN plus RTX provides a synergistically therapeutic effect on MCL cells by enhancing apoptosis and RTX-dependent NK cell-mediated cytotoxicity and may be an optimal combination in the clinical trial of relapsed or refractory MCL.

[Mantle cell lymphoma: case report]

Mantle cell lymphoma (MCL) is a moderately aggressive disease, which is not curable with chemo-immunotherapy. The median survival duration is short, approximately three years. Most of the patients have advanced stage disease at the time of diagnosis. Fifty percent of the patients show infiltration of the bone marrow, in 25% of the MCL patients the gastrointestinal tract is involved, in 25% of patients leukaemic transformation occurs. The tumor cells express pan-B-cell markers and the T-cell marker CD5. The overexpression of cyclin D1 was found as another marker for mantle cell lymphoma. Combined chemotherapy, chemo-immunotherapy, autologous peripheral stem cell (and allogenous) transplantation is the treatment of choice. Our two patients had prolonged survival, in spite of missing the best first line therapy. The survival time after the complex treatment (chemo-immunotherapy, irradiation, surgical intervention, autologous stem cell transplantation) was 80 and 90 months, respectively. In addition to the history of two patients, authors review the current treatment options in mantle cell lymphoma.