Effect of remission status and induction chemotherapy regimen on outcome of autologous stem cell transplantation for mantle cell lymphoma

Evaluating the Therapeutic Potential of Zanubrutinib in the Treatment of Relapsed/Refractory Mantle Cell Lymphoma: Evidence to Date

Mantle cell lymphoma (MCL) is an uncommon B-cell non-Hodgkin lymphoma characterized by an aggressive clinical course in the majority of patients. Despite recent improvements in outcomes, MCL remains incurable and a major therapeutic challenge. BTK inhibitors are the preferred treatment option for patients with relapsed/refractory MCL, including those unfit for chemotherapy or those with chemoresistant disease. In addition to ibrutinib and acalabrutinib, the FDA recently approved zanubrutinib for the treatment of patients with relapsed/refractory MCL based on the results of two Phase 2 clinical trials showing overall response rates of 85–87% with complete responses in 30–77% of patients. Compared with ibrutinib, zanubrutinib is more selective for BTK and has less off-target inhibition, which is thought to limit certain toxicities although direct comparative data are still lacking. This review article summarizes data from clinical trials of currently FDA-approved BTK inhibitors in MCL with a focus on zanubrutinib.

Mantle Cell Lymphoma: Is It Time for a New Treatment Paradigm?

Mantle cell lymphoma is a relatively rare subtype of lymphoma with a great deal of heterogeneity, both clinically and biologically. Since its recognition as a separate entity in the early 1990s though, consistent efforts have led to a significant improvement of overall survival, from a median overall survival of 2.5 years initially to 5-7 years currently. This decades-long and stepwise progress, summarized in the article, definitely accelerated recently, shedding light on a changing paradigm.

RB but not R-HCVAD is a feasible induction regimen prior to auto-HCT in frontline MCL: results of SWOG Study S1106

Aggressive induction chemotherapy followed by autologous haematopoietic stem cell transplant (auto-HCT) is effective for younger patients with mantle cell lymphoma (MCL). However, the optimal induction regimen is widely debated. The Southwestern Oncology Group S1106 trial was designed to assess rituximab plus hyperCVAD/MTX/ARAC (hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone, alternating with high dose cytarabine and methotrexate) (RH) versus rituximab plus bendamustine (RB) in a randomized phase II trial to select a pre-transplant induction regimen for future development. Patients had previously untreated stage III, IV, or bulky stage II MCL and received either 4 cycles of RH or 6 cycles of RB, followed by auto-HCT. Fifty-three of a planned 160 patients were accrued; an unacceptably high mobilization failure rate (29%) on the RH arm prompted premature study closure. The estimated 2-year progression-free survival (PFS) was 81% vs. 82% and overall survival (OS) was 87% vs. 88% for RB and RH, respectively. RH is not an ideal platform for future multi-centre transplant trials in MCL. RB achieved a 2-year PFS of 81% and a 78% MRD negative rate. Premature closure of the study limited the sample size and the precision of PFS estimates and MRD rates. However, RB can achieve a deep remission and could be a platform for future trials in MCL.

Reduced-intensity or myeloablative allogeneic hematopoietic cell transplantation for mantle cell lymphoma: a systematic review

Allogeneic hematopoietic cell transplantation (allo-HCT) is the only known treatment that can offer a cure in mantle cell lymphoma, but it is unclear if regimen dose-intensity offers any advantage. We performed a systematic review/meta-analysis to assess efficacy of allo-HCT using myeloablative or reduced-intensity conditioning. We report results according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. On the basis of a relatively lower nonrelapse mortality and a slightly better progression-free survival/event-free survival and overall survival rates, reduced-intensity allo-HCT regimens appear to be the preferred choice when an allo-HCT is being considered for mantle cell lymphoma. The higher rate of relapse when offering reduced-intensity regimens cannot be ignored but certainly highlights opportunities to incorporate post-transplant strategies to mitigate this risk. A prospective comparative study is ultimately needed to generate more conclusive evidence.

A phase 2 study of Rituximab-Bendamustine and Rituximab-Cytarabine for transplant-eligible patients with mantle cell lymphoma

Chemoimmunotherapy followed by autologous stem cell transplantation (ASCT) is a standard therapy for transplant-eligible patients with newly diagnosed mantle cell lymphoma (MCL). The achievement of complete remission (CR) and minimal residual disease (MRD) negativity are associated with better outcomes. We tested an induction regimen of rituximab/bendamustine followed by rituximab/high-dose cytarabine (RB/RC). This phase 2 study (NCT01661881) enrolled 23 transplant-eligible patients aged 42-69, of whom 70% were MCL international prognostic index low-risk. Patients received three cycles of RB followed by three cycles of RC. The primary endpoint of the trial was the rate of CR after six cycles of therapy, with a rate of 75% considered promising. 96% of patients achieved a CR/unconfirmed CR after treatment, meeting the primary objective. One patient progressed on study, one declined ASCT in CR, and the remaining 21 underwent successful stem cell collection and ASCT. After a median follow-up of 13 months, the progression-free survival rate was 96%. Among 15 MRD-evaluable patients who completed treatment, 93% achieved MRD negativity after RB/RC. In conclusion, RB/RC achieves very high CR and MRD negativity rates in transplant-eligible patients, with a favourable safety profile. RB/RC warrants further comparative studies, and may become a useful alternative to RCHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone)-based induction regimens in this patient population.

Long-term sustained disease control in patients with mantle cell lymphoma with or without active disease after treatment with allogeneic hematopoietic cell transplantation after nonmyeloablative conditioning

BACKGROUND

Previously, early results were reported for allogeneic hematopoietic cell transplantation (HCT) after nonmyeloablative conditioning with 2 Gy of total body irradiation with or without fludarabine and/or rituximab in 33 patients with mantle cell lymphoma (MCL).

METHODS

This study examined the outcomes of 70 patients with MCL and included extended follow-up (median, 10 years) for the 33 initial patients. Grafts were obtained from human leukocyte antigen (HLA)-matched, related donors (47%), unrelated donors (41%), and HLA antigen-mismatched donors (11%).

RESULTS

The 5-year incidence of nonrelapse mortality was 28%. The relapse rate was 26%. The 5-year rates of overall survival (OS) and progression-free survival (PFS) were 55% and 46%, respectively. The 10-year rates of OS and PFS were 44% and 41%, respectively. Eighty percent of surviving patients were off immunosuppression at the last follow-up. The presence of relapsed or refractory disease at the time of HCT predicted a higher rate of relapse (hazard ratio [HR], 2.94; P = .05). Despite this, OS rates at 5 (51% vs 58%) and 10 years (43% vs 45%) were comparable between those with relapsed/refractory disease and those undergoing transplantation with partial or complete remission. A high-risk cytomegalovirus (CMV) status was the only independent predictor of worse OS (HR, 2.32; P = .02). A high-risk CMV status and a low CD3 dose predicted PFS (HR, 2.22; P = .03).

CONCLUSIONS

Nonmyeloablative allogeneic HCT provides a long-term survival benefit for patients with relapsed MCL, including those with refractory disease or multiple relapses.

Treatment strategies in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a distinct B-cell non-Hodgkin's lymphoma (NHL) defined by the translocation t(11;14). MCL combines characteristics of both indolent and aggressive lymphomas, and it is incurable with conventional chemoimmunotherapy but has a more aggressive disease course. Minimal data exist on treatment of patients diagnosed with early-stage disease (stage I-II non-bulky), as this represents only a small portion of the patients diagnosed with MCL, but therapeutic options evaluated in retrospective studies include radiation or combination radiation and chemotherapy. There is a subset of patients with newly diagnosed MCL that can be observed without treatment, but the majority of patients will require treatment at diagnosis. Treatment is often based on age (≤65-70 years of age), comorbidities, and risk factors for disease. The majority of patients who are younger and without significant comorbidities are treated with intensive induction using combination chemoimmunotherapy regimens, many which include consolidation with autologous stem cell transplant (ASCT). Several regimens have been studied that show improved median progression-free survival (PFS) to 3-6 years in this population of patients. The majority of older patients (≥65-70 years of age) are treated with combination chemoimmunotherapy regimens with consideration of rituximab maintenance, with enrollment on a clinical trial encouraged. Therapy for relapsed disease is dependent on prior treatment, age, comorbidities, and toxicities but includes targeted therapies such as the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib, the immunomodulatory agent lenalidomide, the proteasome inhibitor bortezomib, combination chemoimmunotherapy, ASCT, and allogeneic stem cell transplant in selected cases. Several novel agents and targeted therapies alone or in combination are currently being studied and developed in both the upfront and relapsed setting.

Lifting the mantle: Unveiling new treatment approaches in relapsed or refractory mantle cell lymphoma

The management of relapsed/refractory mantle cell lymphoma (MCL) remains a clinical challenge. A standard second-line treatment for relapsed/refractory MCL does not exist. Management of relapsed/refractory MCL requires an individualized treatment approach, incorporating factors such as: functional status, prior treatments, response to prior therapies, and disease biology. Generally, there are two categories of salvage therapy; the first, non-cross-resistant cytotoxic chemotherapeutic agents and, the second, pathway-targeted agents. For transplant eligible patients, the optimal therapy usually consists of salvage, remission re-induction phase followed, whenever possible, by a consolidation phase. Bendamustine and/or high dose cytarabine plus rituximab based chemotherapy represent the most common salvage therapy with an overall response rate of 70-80%. Consolidation with a reduced intensity conditioning allogeneic stem cell transplantation represents the only potentially curative treatment. Overall survival ranges from 30% to 50% at 5 years with this approach. For transplant ineligible patients, ibrutinib is the most effective treatment with an overall response rate of almost 70% and median response duration of 17.5 months. Lacking an effective consolidation, this approach is not considered curative. In this review we characterize the main therapeutic approaches available in this setting and summarize our preferred clinical treatment approach.

Phase I trial of rituximab, cladribine, and temsirolimus (RCT) for initial therapy of mantle cell lymphoma

BACKGROUND

We conducted this trial to determine the maximum tolerated dose (MTD) of temsirolimus added to an established regimen comprised of rituximab and cladribine for the initial treatment of mantle cell lymphoma.

PATIENTS AND METHODS

A standard phase I cohort of three study design was utilized. The fixed doses of rituximab and cladribine were 375 mg/m(2) i.v. day 1 and 5 mg/m(2)/day i.v. days 1-5 of a 28-day cycle, respectively. There were five planned temsirolimus i.v. dose levels: 15 mg day 1; 25 mg day 1; 25 mg days 1 and 15; 25 mg days 1, 8 and 15; and 25 mg days 1, 8, 15, and 22.

RESULTS

Seventeen patients were treated: three each at levels 1-4 and five at dose level 5. The median age was 75 years (52-86 years). Mantle Cell International Prognostic Index (MIPI) scores were low in 6% (1), intermediate in 59% (10), and high in 35% (6) of patients. Five patients were treated at level 5 without dose limiting toxicity. Hematologic toxicity was frequent: grade 3 anemia in 12%, grade 3 thrombocytopenia in 41%, grade 4 thrombocytopenia in 24%, grade 3 neutropenia in 6%, and grade 4 neutropenia in 18% of patients. The overall response rate (ORR) was 94% with 53% complete response and 41% partial response. The median progression-free survival was 18.7 months.

CONCLUSIONS

Temsirolimus 25 mg i.v. weekly may be safely added to rituximab and cladribine at 375 mg/m(2) i.v. day 1 and 5 mg/m(2)/day i.v. days 1-5 of a 28-day cycle, respectively. This regimen had promising preliminary activity in an elderly cohort of patients with mantle cell lymphoma.

CLINICALTRIALSGOV IDENTIFIER

NCT00787969.

Autologous or reduced-intensity conditioning allogeneic hematopoietic cell transplantation for chemotherapy-sensitive mantle-cell lymphoma: analysis of transplantation timing and modality

PURPOSE

To examine the outcomes of patients with chemotherapy-sensitive mantle-cell lymphoma (MCL) following a first hematopoietic stem-cell transplantation (HCT), comparing outcomes with autologous (auto) versus reduced-intensity conditioning allogeneic (RIC allo) HCT and with transplantation applied at different times in the disease course.

PATIENTS AND METHODS

In all, 519 patients who received transplantations between 1996 and 2007 and were reported to the Center for International Blood and Marrow Transplant Research were analyzed. The early transplantation cohort was defined as those patients in first partial or complete remission with no more than two lines of chemotherapy. The late transplantation cohort was defined as all the remaining patients.

RESULTS

Auto-HCT and RIC allo-HCT resulted in similar overall survival from transplantation for both the early (at 5 years: 61% auto-HCT v 62% RIC allo-HCT; P = .951) and late cohorts (at 5 years: 44% auto-HCT v 31% RIC allo-HCT; P = .202). In both early and late transplantation cohorts, progression/relapse was lower and nonrelapse mortality was higher in the allo-HCT group. Overall survival and progression-free survival were highest in patients who underwent auto-HCT in first complete response. Multivariate analysis of survival from diagnosis identified a survival benefit favoring early HCT for both auto-HCT and RIC allo-HCT.

CONCLUSION

For patients with chemotherapy-sensitive MCL, the optimal timing for HCT is early in the disease course. Outcomes are particularly favorable for patients undergoing auto-HCT in first complete remission. For those unable to achieve complete remission after two lines of chemotherapy or those with relapsed disease, either auto-HCT or RIC allo-HCT may be effective, although the chance for long-term remission and survival is lower.

Plerixafor to the rescue: boosting peripheral blood stem cell mobilization in patients previously treated with hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone/methotrexate, cytarabine (Hyper-CVAD) chemotherapy

Hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone/methotrexate, cytarabine (Hyper-CVAD) chemotherapy exerts deleterious effects on peripheral blood stem cell (PBSC) mobilization. We retrospectively reviewed the use of plerixafor to salvage mobilization in 18 Hyper-CVAD treated patients who initially mobilized poorly with chemotherapy and granulocyte colony stimulating factor (G-CSF). After plerixafor administration the median peripheral blood (PB) CD34 + count rose from 3.74/μL (0-17/μL) to 6.85/μL (0-47.2/μL). The patients collected a median of 1.64 (0.21-5.56) × 10(6) CD34 + cells/kg with a median number of 3 (1-4) doses in the same collection cycle, and 11 patients reached the 2.0 × 10(6) CD34 + cells/kg minimum required for transplant. Six patients were remobilized later with G-CSF and plerixafor, and three additional patients reached this goal. For these 14 patients the median number of doses of plerixafor required to reach 2.0 × 10(6) CD34 + cells/kg was 3 (range 1-4). In conclusion, plerixafor can be utilized successfully in many cases to overcome the effects of Hyper-CVAD on PBSC mobilization.

Specific features identify patients with relapsed or refractory mantle cell lymphoma benefitting from autologous hematopoietic cell transplantation

Outcomes with autologous hematopoietic cell transplantation (auto HCT) for relapsed and/or refractory mantle cell lymphoma (MCL) are typically poor. We hypothesized that certain factors could predict which patients experience a favorable outcome with this approach. We thus developed a predictive score from a cohort of 67 such patients using 3 factors independently associated with progression-free survival (PFS): (1) simplified Mantle Cell Lymphoma International Prognostic Index score before auto HCT (hazard ratio [HR], 2.9; P = .002); (2) B symptoms at diagnosis (HR, 2.7; P = .005); and (3) remission quotient, calculated by dividing the time, in months, from diagnosis to auto HCT by the number of prior treatments (HR, 1.4; P = .02). The estimated 5-year PFS for favorable-risk patients (n = 23) and unfavorable-risk patients (n = 44) were 58% (95% confidence interval [CI], 34% to 75%) and 15% (95% CI, 6% to 28%), respectively. These factors also independently predicted overall survival. In summary, we have defined 3 simple factors that can identify patients with relapsed/refractory MCL who derive a durable benefit from salvage auto HCT.

Initial therapy of mantle cell lymphoma

Mantle cell lymphoma is a well-recognized distinct clinicopathologic subtype of B-cell non-Hodgkin lymphoma. The current World Health Organization (WHO) classification subdivides this entity into aggressive and other variants. The disease has a predilection for older males, and patients typically present at an advanced stage with frequent splenomegaly and extranodal involvement including bone marrow, peripheral blood, gastrointestinal, and occasional central nervous system involvement. Early studies of therapy outcomes in this disease revealed that while response rates where high, relapse was expected after a limited period of time. Prolonged survival was uncommon, with initial median survival rates typically in the 3-4-year range. Those with a high proliferative rate, blastoid morphology, and selected clinical features were recognized as having a worse prognosis. Therapeutic approaches have diverged into aggressive therapies with high response rates and promising progression free survival rates, which may be applied to younger healthy patients, and less aggressive approaches. Aggressive therapies include intensive chemotherapy alone or chemotherapy followed by autologous stem cell transplant, which has been shown to be most effective when applied in first remission. Whether these more intense therapies result in improved survival as compared with less aggressive therapies is not well established. Allogeneic transplant has also been investigated, although high treatment-related mortality and the risk of chronic graft versus host disease and the relatively advanced age of this patient population have tempered enthusiasm for this approach. A number of less aggressive therapies have been shown to produce promising results. Consolidation and maintenance strategies are an active area of investigation. A number of newer agents have shown promising activity in relapsed disease, and are being investigated in the front-line setting. Overall survival rates are improving in this disease, with current studies suggesting a median survival of 5 or more years.

Allogeneic hematopoietic cell transplantation for chemotherapy-unresponsive mantle cell lymphoma: a cohort analysis from the center for international blood and marrow transplant research

Patients with chemorefractory mantle cell lymphoma (MCL) have a poor prognosis. We used the Center for International Blood and Marrow Transplant Research database to study the outcome of 202 patients with refractory MCL who underwent allogeneic hematopoietic cell transplantation (allo-HCT) using either myeloablative (MA) or reduced-intensity/nonmyeloablative conditioning (RIC/NST), during 1998-2010. We analyzed nonrelapse mortality (NRM), progression/relapse, progression-free survival (PFS), and overall survival (OS). Seventy-four patients (median age, 54 years) received MA, and 128 patients (median age, 59 years) received RIC/NST. Median follow-up after allo-HCT was 35 months in the MA group and 43 months in the RIC/NST group. At 3 years post-transplantation, no significant between-group differences were seen in terms of NRM (47% in MA versus 43% in RIC/NST; P = .68), relapse/progression (33% versus 32%; P = .89), PFS (20% versus 25%; P = .53), or OS (25% versus 30%; P = .45). Multivariate analysis also revealed no significant between-group differences in NRM, relapse, PFS, or OS; however, receipt of a bone marrow or T cell-depleted allograft was associated with an increased risk of NRM and inferior PFS and OS. Our data suggest that despite a refractory disease state, approximately 25% of patients with MCL can attain durable remission after allo-HCT, and conditioning regimen intensity does not influence outcome of allo-HCT.

Reappraising the role of autologous transplantation for indolent B-cell lymphomas in the chemoimmunotherapy era: is it still relevant?

The role of autologous hematopoietic cell transplantation (auto-HCT) in the management of indolent non-Hodgkin lymphomas (NHL) is shrouded in controversy. The outcomes of conventional therapies for many indolent lymphoma subtypes have dramatically improved over the last several years with the use of monoclonal antibodies, maintenance therapy programs and with the incorporation of radio-immunoconjugates. These significant advances in the armamentarium of lymphoma therapeutics warrant reappraisal of the current role of auto-HCT in the treatment algorithm of indolent NHL. Prospective randomized studies comparing contemporary chemoimmunotherapies against auto-HCT are lacking, leading to significant debate about the role and timing of auto-HCT for indolent NHL in the modern era. Although autografting for follicular lymphoma (FL) in first remission has been largely abandoned, it remains a useful modality for relapsed disease, especially for the subgroup of patients who are not candidates for allogeneic transplantation with a curative intent. Auto-HCT can provide durable disease control in chemosensitive transformed FL and mantle cell lymphoma (MCL) in first remission, with relatively low toxicity, and remains appropriate in chemoimmunotherapy era. Contemporary data are also reviewed to clarify the often underutilized role of autografting in relapsed MCL and other less frequent indolent NHL histologies. The biological basis of the increased risks of second malignancies with auto-HCT are reviewed to identify strategies designed to mitigate this risk by, for example, avoiding exposure to genotoxic agents, planning early stem cell collection/cryopreservation and minimizing the use of TBI with transplant conditioning, and so on. Genetic testing able to identify patients at high risk of therapy-related complications and novel post-transplant immune therapies with the potential of transforming autografting in indolent NHL from a remission-extending therapy to a curative modality are discussed to examine the possibly expanding role of auto-HCT for lymphoid malignancies in the coming years.

Autologous stem-cell transplantation in patients with mantle cell lymphoma beyond 65 years of age: a study from the European Group for Blood and Marrow Transplantation (EBMT)

BACKGROUND

Limited experience is available on the feasibility and efficacy of autologous stem-cell transplantation (ASCT) in patients with mantle cell lymphoma (MCL) beyond 65 years.

DESIGN AND METHODS

We analysed 712 patients with MCL treated with ASCT from 2000 to 2007 and reported to the European Group for Blood and Marrow Transplantation registry. Patients>65 years were compared with patients<65 years for the end points non-relapse mortality (NRM), relapse incidence, progression-free survival (PFS), and overall survival (OS).

RESULTS

Seventy-nine patients were ≥65 years old. Median time from diagnosis to ASCT was longer in the elderly patients (11 versus 9 months, P=0.005); they had more commonly received at least two treatment lines (62.0% versus 47.9%, P=0.02) and were less commonly in first complete remission at ASCT (35.4% versus 51.2%, P=0.002). Median follow-up after ASCT was 19 and 25 months, respectively. NRM was comparable at 3 months (3.8% versus 2.5%) and at 5 years (5.6% versus 5.0%). There were no differences in relapse rate (66% versus 55% at 5 years), PFS (29% versus 40%) and OS (61% versus 67%) between both populations of patients.

CONCLUSION

ASCT beyond 65 years of age is feasible in selected patients with MCL and results in similar disease control and survival as in younger patients.

Mantle cell lymphoma international prognostic index but not pretransplantation induction regimen predicts survival for patients with mantle-cell lymphoma receiving high-dose therapy and autologous stem-cell transplantation

PURPOSE

High-dose therapy (HDT) and autologous stem-cell transplantation (ASCT) are frequently used in an attempt to improve outcome in patients with mantle-cell lymphoma (MCL); however, the importance of intensive induction regimens before transplantation is unknown.

PATIENTS AND METHODS

To address this question, we evaluated baseline characteristics, time to treatment, induction regimen, disease status at the time of transplantation, and MIPI score at diagnosis and their associations with survival in 118 consecutive patients with MCL who received HDT and ASCT at our centers.

RESULTS

The MIPI was independently associated with survival after transplantation in all 118 patients (hazard ratio [HR], 3.5; P < .001) and in the 85 patients who underwent ASCT as initial consolidation (HR, 7.2; P < .001). Overall survival rates were 93%, 60%, and 32% at 2.5 years from ASCT for all patients with low-, intermediate-, and high-risk MIPI, respectively. Low-risk MIPI scores were more common in the intensive induction group than the standard induction group in all patients (64% v 46%, respectively; P = .03) and in the initial consolidation group (66% v 45%, respectively; P = .03). After adjustment for the MIPI, an intensive induction regimen was not associated with improved survival after transplantation in all patients (HR, 0.5; P = .10), the initial consolidation group (HR, 1.1; P = .86), or patients ≤ 60 years old (HR, 0.6; P = .50). Observation of more than 3 months before initiating therapy did not yield inferior survival (HR, 2.1; P = .12) after adjustment for the MIPI in patients receiving ASCT.

CONCLUSION

An intensive induction regimen before HDT and ASCT was not associated with improved survival after adjusting for differences in MIPI scores at diagnosis.

Transplantation for non-Hodgkin lymphoma

High-dose therapy followed by autologous hematopoietic stem cell transplantation (auto-HCT) has become the treatment of choice for patients with relapsed aggressive non-Hodgkin lymphoma (NHL). However, relapse remains the most common cause of treatment failure after auto-HCT. More intensive regimens incorporating radioimmunotherapy into high-dose regimens have been developed to prevent relapse. The role of auto-HCT for follicular lymphoma and mantle cell lymphoma remain inconclusive. Since prognosis of patients with peripheral T-cell lymphoma, not otherwise specified are very poor with conventional chemotherapy, auto-HCT during first remission is being explored in peripheral T-cell lymphoma. Given the lower risk of relapse after allogeneic HCT (allo-HCT) in NHL, allo-HCT has been performed in patients with refractory or relapsed NHL, especially after auto-HCT failure. However, the transplant-related mortality remains high after myeloablative allo-HCT. Reduced-intensity conditioning followed by allo-HCT has been shown to reduce transplant-related mortality but graft-versus-host disease continues to be the major problem, thus the role of allo-HCT in NHL remains an investigational approach for NHL. The outcomes of auto-HCT and allo-HCT for various lymphomas are reviewed.

An XRCC1 polymorphism is associated with the outcome of patients with lymphoma undergoing autologous stem cell transplant

High-dose chemotherapy supported by autologous stem cell transplant (ASCT) remains the treatment of choice for patients with lymphoma failing first-line chemotherapy. Recent evidence suggests a relationship between the genetic variations in genes involved in DNA repair and the outcome of patients with a number of malignancies. In this work, we retrospectively evaluated the influence of an XRCC1 polymorphism (rs25487) on the treatment results in a series of 73 patients with lymphoma subjected to ASCT. The factors correlated to overall survival were the disease status at transplant and XRCC1 genotype. Carriers of a mutant A allele had a two-fold higher risk of death than those with the wild-type genotype. In addition, patients harboring one or two copies of the A allele (GA/AA) were 4.5-fold more likely to develop therapy-related acute myeloid (t-AML). Thus, the cumulative probability of t-AML at 10 years was 37 ± 13% in patients with the mutant A allele as compared to 8.5 ± 6% in the remaining cases (p = 0.04). Our findings suggest that genetic variation in the DNA repair gene XRCC1 may play a role in the results of transplant in patients with lymphoma.

Temsirolimus in the treatment of relapsed or refractory mantle cell lymphoma

Mantle cell lymphoma (MCL) is a rare and aggressive subtype of lymphoma associated with a poor prognosis. Chemotherapy is the mainstay of frontline treatment for patients with this disease. Despite high response rates to combination chemotherapy regimens, the majority of patients relapse within a few years of treatment. Therefore, finding efficacious treatments for relapsed or refractory disease has become a growing area of clinical research. The mammalian target of rapamycin (mTOR) is responsible for integrating cell signals from growth factors, hormones, and nutrients and communicating energy status. Scientific research on aberrant molecular pathways in cancer has revealed that several proteins along the mTOR pathway may be upregulated in this and other types of lymphoma. Temsirolimus is the first mTOR inhibitor that has shown clinical efficacy in treating MCL that has relapsed after frontline treatments.

Current treatment standards and emerging strategies in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a unique subtype of B-cell non-Hodgkin lymphomas characterized by the chromosomal translocation t(11;14)(q13;q32) and nuclear cyclin D1 overexpression in the vast majority of cases. Most patients present with advanced stage disease, often with extranodal dissemination, and pursue an aggressive clinical course in the majority of cases. Recent improvement has been achieved by the successful introduction of monoclonal antibodies and dose-intensified approaches including autologous stem cell transplantation (ASCT) strategies. With the exception of allogeneic hematopoietic stem cell transplantation, current treatment approaches are non-curative and the corresponding survival curves are characterized by a delayed, but continuous decline and a median survival of 4 to 6 years. However, recently a subset (15%) of long-term survivors have been identified with a rather indolent clinical course even after conventional treatment strategies only. Emerging strategies such as proteasome inhibitors, IMIDs, mTOR inhibitors and others are based on the dysregulated control of cell cycle machinery and impaired apoptotic pathways. Monotherapy of these compounds achieves efficacy comparable to conventional chemotherapy in relapsed MCL, and combination strategies are currently being investigated in numerous trials; however, their introduction into clinical practice and current treatment algorithms remains a challenge.