High-dose chemotherapy and autologous stem cell transplant in elderly patients with primary CNS lymphoma: a pilot study

Myeloablative vs nonmyeloablative consolidation for primary central nervous system lymphoma: results of Alliance 51101

ABSTRACT

Although it is evident that standard-dose whole-brain radiotherapy as consolidation is associated with significant neurotoxicity, the optimal consolidative strategy for primary central nervous system lymphoma (PCNSL) is not defined. We performed a randomized phase 2 clinical trial via the US Alliance cancer cooperative group to compare myeloablative consolidation supported by autologous stem cell transplantation with nonmyeloablative consolidation after induction therapy for PCNSL. To our knowledge, this is the first randomized trial to be initiated that eliminates whole-brain radiotherapy as a consolidative approach in newly diagnosed PCNSL. Patients aged 18 to 75 years were randomly assigned in a 1:1 manner to induction therapy (methotrexate, temozolomide, rituximab, and cytarabine) followed by consolidation with either thiotepa plus carmustine and autologous stem cell rescue vs induction followed by nonmyeloablative, infusional etoposide plus cytarabine. The primary end point was progression-free survival (PFS). A total of 113 patients were randomized, and 108 (54 in each arm) were evaluable. More patients in the nonmyeloablative arm experienced progressive disease or death during induction (28% vs 11%; P = .05). Thirty-six patients received autologous stem cell transplant, and 34 received nonmyeloablative consolidation. The estimated 2-year PFS was higher in the myeloablative vs nonmyeloablative arm (73% vs 51%; P = .02). However, a planned secondary analysis, landmarked at start of the consolidation, revealed that the estimated 2-year PFS in those who completed consolidation therapy was not significantly different between the arms (86% vs 71%; P = .21). Both consolidative strategies yielded encouraging efficacy and similar toxicity profiles. This trial was registered at www.clininicals.gov as #NCT01511562.

Primary central nervous system lymphomas: EHA-ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up

This EHA-ESMO Clinical Practice Guideline provides key recommendations for managing primary DLBCL of the CNS.The guideline covers clinical, imaging and pathological diagnosis, staging and risk assessment, treatment and follow-up.Algorithms for first-line and salvage treatments are provided.The author group encompasses a multidisciplinary group of experts from different institutions and countries in Europe.Recommendations are based on available scientific data and the authors' collective expert opinion.

Survival, neurocognitive function, and health-related quality of life outcomes after rituximab-methotrexate, BCNU, teniposide, and prednisolone for primary CNS lymphoma: Final results of the HOVON 105/ALLG NHL 24 study

BACKGROUND

Studies on the efficacy of rituximab in primary CNS lymphoma (PCNSL) reported conflicting results. Our international randomized phase 3 study showed that the addition of rituximab to high-dose methotrexate, BCNU, teniposide, and prednisolone (MBVP) in PCNSL was not efficacious in the short term. Here we present long-term results after a median follow-up of 82.3 months.

METHODS

One hundred and ninety-nine eligible newly diagnosed, nonimmunocompromised patients with PCNSL aged 18-70 years with WHO performance status 0-3 was randomized between treatment with MBVP chemotherapy with or without rituximab, followed by high-dose cytarabine consolidation in responding patients, and reduced-dose WBRT in patients aged ≤ 60 years. Event-free survival was the primary endpoint. Overall survival rate, neurocognitive functioning (NCF), and health-related quality of life (HRQoL) were additionally assessed, with the IPCG test battery, EORTC QLQ-C30 and QLQ-BN20 questionnaires, respectively.

RESULTS

For event-free survival, the hazard ratio was 0.85, 95% CI 0.61-1.18, P = .33. Overall survival rate at 5 years for MBVP and R-MBVP was 49% (39-59) and 53% (43-63) respectively. In total, 64 patients died in the MBVP arm and 55 in the R-MBVP arm, of which 69% were due to PCNSL. At the group level, all domains of NCF and HRQoL improved to a clinically relevant extent after treatment initiation, and remained stable thereafter up to 60 months of follow-up, except for motor speed which deteriorated between 24 and 60 months. Although fatigue improved initially, high levels persisted in the long term.

CONCLUSIONS

Long-term follow-up confirms the lack of added value of rituximab in addition to MBVP and HD-cytarabine for PCNSL.

Relevance of different prognostic scores in primary CNS lymphoma in the era of intensified treatment regimens: A retrospective, multicenter analysis of 174 patients

OBJECTIVES

Treatment intensification (including consolidative high-dose chemotherapy with autologous stem cell transplantation [HDT-ASCT]) significantly improved outcome in primary central nervous system lymphoma (PCNSL) patients.

METHODS

We conducted a multicenter, retrospective analysis of newly diagnosed PCNSL patients, treated with intensified treatment regimens. The following scores were evaluated in terms of overall survival (OS) and progression-free survival (PFS): Memorial Sloan-Kettering Cancer Center (MSKCC), International Extranodal Lymphoma Study Group (IELSG), and three-factor (3F) prognostic score. Further, all scores were comparatively investigated for model quality and concordance.

RESULTS

Altogether, 174 PCNSL patients were included. One hundred and five patients (60.3%) underwent HDT-ASCT. Two-year OS and 2-year PFS for the entire population were 73.3% and 48.5%, respectively. The MSKCC (p = .003) and 3F score (p < .001), but not the IELSG score (p = .06), had the discriminatory power to identify different risk groups for OS. In regard to concordance, the 3F score (C-index [0.71]) outperformed both the MSKCC (C-index [0.64]) and IELSG (C-index [0.53]) score. Moreover, the superiority of the 3F score was shown for PFS, successfully stratifying patients in three risk groups, which also resulted in the highest C-index (0.66).

CONCLUSION

The comparative analysis of established PCNSL risk scores affirm the clinical utility of the 3F score stratifying the widest prognostic spectrum among PCNSL patients treated with intensified treatment approaches.

High-dose chemotherapy and autologous haematopoietic stem-cell transplantation in older, fit patients with primary diffuse large B-cell CNS lymphoma (MARTA): a single-arm, phase 2 trial

BACKGROUND

Available treatments for older patients with primary diffuse large B-cell CNS lymphoma (PCNSL) offer progression-free survival of up to 16 months. We aimed to investigate an intensified treatment of high-dose chemotherapy and autologous haematopoietic stem-cell transplantation (HSCT) in older patients with PCNSL.

METHODS

MARTA was a prospective, single-arm, phase 2 study done at 15 research hospitals in Germany. Patients aged 65 years or older with newly diagnosed, untreated PCNSL were enrolled if they had an Eastern Cooperative Oncology Group performance status of 0-2 and were fit for high-dose chemotherapy and autologous HSCT. Induction treatment consisted of two 21-day cycles of high-dose intravenous methotrexate 3·5 g/m2 (day 1), intravenous cytarabine 2 g/m2 twice daily (days 2 and 3), and intravenous rituximab 375 mg/m2 (days 0 and 4) followed by high-dose chemotherapy with intravenous rituximab 375 mg/m2 (day -8), intravenous busulfan 3·2 mg/kg (days -7 and -6), and intravenous thiotepa 5 mg/kg (days -5 and -4) plus autologous HSCT. The primary endpoint was progression-free survival at 12 months in all patients who met eligibility criteria and started treatment. The study was registered with the German clinical trial registry, DRKS00011932, and recruitment is complete.

FINDINGS

Between Nov 28, 2017, and Sept 16, 2020, 54 patients started induction treatment and 51 were included in the full analysis set. Median age was 71 years (IQR 68-75); 27 (53%) patients were female and 24 (47%) were male. At a median follow-up of 23·0 months (IQR 16·8-37·4), 23 (45%) of 51 patients progressed, relapsed, or died. 12-month progression-free survival was 58·8% (80% CI 48·9-68·2; 95% CI 44·1-70·9). During induction treatment, the most common grade 3-5 toxicities were thrombocytopenia and leukopenia (each in 52 [96%] of 54 patients). During high-dose chemotherapy and autologous HSCT, the most common grade 3-5 toxicity was leukopenia (37 [100%] of 37 patients). Treatment-related deaths were reported in three (6%) of 54 patients, all due to infectious complications.

INTERPRETATION

Although the primary efficacy threshold was not met, short induction followed by high-dose chemotherapy and autologous HSCT is active in selected older patients with PCNSL and could serve as a benchmark for comparative trials.

FUNDING

Else Kröner-Fresenius Foundation, Riemser Pharma, and Medical Center-University of Freiburg.

Improved early outcome prediction by MRI-based 3D tumor volume assessment in patients with CNS lymphomas

BACKGROUND

Central nervous system lymphomas (CNSL) display remarkable clinical heterogeneity, yet accurate prediction of outcomes remains challenging. The IPCG criteria are widely used in routine practice for the assessment of treatment response. However, the value of the IPCG criteria for ultimate outcome prediction is largely unclear, mainly due to the uncertainty in delineating complete from partial responses during and after treatment.

METHODS

We explored various MRI features including semi-automated 3D tumor volume measurements at different disease milestones and their association with survival in 93 CNSL patients undergoing curative-intent treatment.

RESULTS

At diagnosis, patients with more than 3 lymphoma lesions, periventricular involvement, and high 3D tumor volumes showed significantly unfavorable PFS and OS. At first interim MRI during treatment, the IPCG criteria failed to discriminate outcomes in responding patients. Therefore, we randomized these patients into training and validation cohorts to investigate whether 3D tumor volumetry could improve outcome prediction. We identified a 3D tumor volume reduction of ≥97% as the optimal threshold for risk stratification (=3D early response, 3D_ER). Applied to the validation cohort, patients achieving 3D_ER had significantly superior outcomes. In multivariate analyses, 3D_ER was independently prognostic of PFS and OS. Finally, we leveraged prognostic information from 3D MRI features and circulating biomarkers to build a composite metric that further improved outcome prediction in CNSL.

CONCLUSIONS

We developed semi-automated 3D tumor volume measurements as strong and independent early predictors of clinical outcomes in CNSL patients. These radiologic features could help improve risk stratification and help guide future treatment approaches.

Different patterns of failure in two treatment regimens for primary central nervous system lymphoma, a retrospective analysis of 124 cases in Taiwan

To explore prognostic factors and outcomes of primary central nervous system lymphoma (PCNSL) of diffuse large B-cell lymphoma (DLBCL) in Taiwan, 124 PCNSL-DLBCL patients (from 1995 to 2021) were retrospectively analyzed. Mainly, two treatment modalities including sandwich chemoradiotherapy and modified MATRix regimen were employed in these patients. Overall survival (OS) was determined by log-rank test and time-dependent Cox analysis. Median OS of all patients was 27.1 months. 47 (37.9%) patients who underwent sandwich chemoradiotherapy had a complete remission (CR) rate of 87.2%, median OS of 53.9 months, and progression free survival (PFS) of 42.9 months. 11 (8.9%) patients who underwent modified MATRix regimen had CR rate of 72.7%, median OS of 18.9, and PFS of 11.2 months. There are no significant OS differences between treatment groups or addition of Rituximab. Patients treated with the modified MATRix regimen experienced a higher early mortality rate followed by a survival plateau. IELSG low-risk group had significantly improved OS and PFS than IELSG intermediate- or high-risk group. In multivariant analysis, age > 60 years old and bilateral cerebral lesions are associated with significantly inferior OS. Sandwich chemoradiotherapy demonstrated better early survival and reduced treatment-related toxicity for PCNSL patients compared to the modified MATRix regimen. However, the long-term follow-up revealed a higher rate of treatment failure events in the sandwich chemoradiotherapy group. IELSG and MSKCC scores served as reliable risk assessment models. Incorporating bilateral cerebral lesions as a risk factor further improved risk evaluation.

Treatment of new-onset primary central nervous system lymphoma in elderly patients using RMPV chemotherapy: a single-institution experience

The prognosis of primary central nervous system lymphoma (PCNSL) in the elderly remains poor. We aimed to evaluate the outcome of rituximab, methotrexate, procarbazine, and vincristine (RMPV) chemotherapy in elderly patients with new-onset PCNSL. Twenty-eight patients aged ≥ 70 years treated for PCNSL between 2010 and 2020 were examined retrospectively. Nineteen patients received RMPV and nine did not qualify. Patients received five to seven cycles of RMPV plus response-adapted whole-brain radiotherapy (WBRT) and cytarabine. Ten of the 19 patients who received RMPV (52.6%) completed the induction, but only four patients (21.1%) completed RMPV chemotherapy, WBRT 23.4 Gy, and cytarabine. Median progression-free survival (PFS) and overall survival (OS) in the RMPV group was 54.4 and 85.0 months, respectively. Both PFS and OS were significantly longer in patients who received RMPV chemotherapy than in those who did not, and in patients who started but did not complete RMPV than in those who did not receive RMPV. Patients who received incomplete RMPV tended to have a favorable prognosis. Initial treatment with RMPV chemotherapy was effective in elderly patients with PCNSL. Adjusting the number of courses of RMPV may improve the prognosis of elderly patients with PCNSL, but further verification is necessary.

Age-adjusted high-dose chemotherapy followed by autologous stem cell transplantation or conventional chemotherapy with R-MP as first-line treatment in elderly primary CNS lymphoma patients - the randomized phase III PRIMA-CNS trial

BACKGROUND

Older primary central nervous system lymphoma (PCNSL) patients have an inferior prognosis compared to younger patients because available evidence on best treatment is scarce and treatment delivery is challenging due to comorbidities and reduced performance status. High-dose chemotherapy and autologous stem cell transplantation (HCT-ASCT) after high-dose methotrexate (MTX)-based immuno-chemotherapy has become an increasingly used treatment approach in eligible elderly PCNSL patients with promising feasibility and efficacy, but has not been compared with conventional chemotherapy approaches. In addition, eligibility for HCT-ASCT in elderly PCNSL is not well defined. Geriatric assessment (GA) may be helpful in selecting patients for the best individual treatment choice, but no standardized GA exists to date. A randomized controlled trial, incorporating a GA and comparing age-adapted HCT-ASCT treatment with conventional chemotherapy is needed.

METHODS

This open-label, multicenter, randomized phase III trial with two parallel arms will recruit 310 patients with newly diagnosed PCNSL > 65 years of age in 40 centers in Germany and Austria. The primary objective is to demonstrate that intensified chemotherapy followed by consolidating HCT-ASCT is superior to conventional chemotherapy with rituximab, MTX, procarbazine (R-MP) followed by maintenance with procarbazine in terms of progression free survival (PFS). Secondary endpoints include overall survival (OS), event free survival (EFS), (neuro-)toxicity and quality of life (QoL). GA will be conducted at specific time points during the course of the study. All patients will be treated with a pre-phase rituximab-MTX (R-MTX) cycle followed by re-assessment of transplant eligibility. Patients judged transplant eligible will be randomized (1:1). Patients in arm A will be treated with 3 cycles of R-MP followed by maintenance therapy with procarbazine for 6 months. Patients in arm B will be treated with 2 cycles of MARTA (R-MTX/AraC) followed by busulfan- and thiotepa-based HCT-ASCT.

DISCUSSION

The best treatment strategy for elderly PCNSL patients remains unknown. Treatments range from palliative to curative but more toxic therapies, and there is no standardized measure to select patients for the right treatment. This randomized controlled trial will create evidence for the best treatment strategy with the focus on developing a standardized GA to help define eligibility for an intensive treatment approach.

TRIAL REGISTRATION

German clinical trials registry DRKS00024085 registered March 29, 2023.

Central nervous system lymphomas-Assessment and treatment and prevention of central nervous system relapse

In this review focused on lymphoma and the central nervous system (CNS), we summarize recent developments in the management of primary (PCNSL) and secondary CNS lymphoma (SCNSL), treatment of CNS lymphoma in the older population, the neuroradiological assessment of CNS lymphoma and finally highlight the ongoing debate on optimal CNS prophylaxis. The section on PCNSL focuses on the different approaches available for frontline treatment in Europe and the United States and discusses consolidation strategies. We then highlight available strategies to treat PCNSL in the elderly population, an area of unmet need. New therapies aiming at minimizing toxicity and prioritizing quality of life are emerging for these patients. Secondary CNS lymphoma, especially in the relapsed/refractory setting is another area of unmet need, and the efficacy of CAR-T cell therapy is being explored. We provide an overview of the imaging challenges in the neuroradiological assessment of CNS lymphoma. Finally, the section on CNS prophylaxis summarizes recent findings from large retrospective studies challenging the efficacy of present approaches to prophylaxis in higher-risk patients with lymphoma.

Primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a diffuse large B cell lymphoma in which the brain, spinal cord, leptomeninges and/or eyes are exclusive sites of disease. Pathophysiology is incompletely understood, although a central role seems to comprise immunoglobulins binding to self-proteins expressed in the central nervous system (CNS) and alterations of genes involved in B cell receptor, Toll-like receptor and NF-κB signalling. Other factors such as T cells, macrophages or microglia, endothelial cells, chemokines, and interleukins, probably also have important roles. Clinical presentation varies depending on the involved regions of the CNS. Standard of care includes methotrexate-based polychemotherapy followed by age-tailored thiotepa-based conditioned autologous stem cell transplantation and, in patients unsuitable for such treatment, consolidation with whole-brain radiotherapy or single-drug maintenance. Personalized treatment, primary radiotherapy and only supportive care should be considered in unfit, frail patients. Despite available treatments, 15-25% of patients do not respond to chemotherapy and 25-50% relapse after initial response. Relapse rates are higher in older patients, although the prognosis of patients experiencing relapse is poor independent of age. Further research is needed to identify diagnostic biomarkers, treatments with higher efficacy and less neurotoxicity, strategies to improve the penetration of drugs into the CNS, and roles of other therapies such as immunotherapies and adoptive cell therapies.

Challenges in the management of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare extranodal non-Hodgkin lymphoma. Stereotactic biopsy remains the gold standard for the pathological diagnosis of PCNSL. However, certain new auxiliary diagnostic methods are considered to have good application prospects; these include cytokine and tumor circulating DNA, among others. Although new drugs such as immunomodulators, immune checkpoint inhibitors, chimeric antigen receptor T-cells, and Bruton tyrosine kinase inhibitors have brought hope owing to their improved efficacy, the high recurrence rate and subsequent high mortality remain barriers to long-term survival. Increasing emphasis is therefore being placed on consolidation treatments. Consolidation treatment strategies include whole brain radiotherapy, autologous hematopoietic stem cell transplantation, and non-myeloablative chemotherapy. As studies directly comparing the effectiveness and safety of different consolidation treatment schemes are lacking, the optimal consolidation strategy remains uncertain. This article will review the diagnosis and treatment of PCNSL, focusing on the progress in research pertaining to consolidation therapy.

Recent advances in the diagnosis and the treatment of primary CNS lymphoma

This review focuses on the recent progress in the management of primary central nervous system lymphoma (PCNSL). Multiomic analyses allowed to better understand the tumorigenesis of PCNSL and to establish a molecular classification with prognostic value that will optimize patient management and guide future targeted approaches. Cooperative clinical trials have demonstrated the feasibility and efficacy, in selected fit patients, of high-dose chemotherapy with autologous stem cell transplantation as post-induction consolidation, that will progressively replace whole brain radiotherapy associated with a much higher risk of delayed neurotoxicity. Several novel treatments have shown efficacy and overall good tolerance in PCNSL patients, such as Bruton's tyrosine kinase (BTK) inhibitors, imids, immune checkpoint inhibitors and chimeric antigen receptor T-cells (CAR-T). This opens promising therapeutic perspectives to improve the current standard treatment, especially for elderly and unfit patients who represent a growing population.

Prevention and management of secondary central nervous system lymphoma

Secondary central nervous system (CNS) lymphoma (SCNSL) is defined by the involvement of the CNS, either at the time of initial diagnosis of systemic lymphoma or in the setting of relapse, and can be either isolated or with synchronous systemic disease. The risk of CNS involvement in patients with diffuse large B-cell lymphoma is approximately 5%; however, certain clinical and biological features have been associated with a risk of up to 15%. There has been growing interest in improving the definition of patients at increased risk of CNS relapse, as well as identifying effective prophylactic strategies to prevent it. SCNSL often occurs within months of the initial diagnosis of lymphoma, suggesting the presence of occult disease at diagnosis in many cases. The differing presentations of SCNSL create the therapeutic challenge of controlling both the systemic disease and the CNS disease, which uniquely requires agents that penetrate the blood-brain barrier. Outcomes are generally poor with a median overall survival of approximately 6 months in retrospective series, particularly in those patients presenting with SCNSL after prior therapy. Prospective studies of intensive chemotherapy regimens containing high-dose methotrexate, followed by hematopoietic stem cell transplantation have shown the most favorable outcomes, especially for patients receiving thiotepa-based conditioning regimens. However, a proportion of patients will not respond to induction therapies or will subsequently relapse, indicating the need for more effective treatment strategies. In this review we focus on the identification of high-risk patients, prophylactic strategies and recent treatment approaches for SCNSL. The incorporation of novel agents in immunochemotherapy deserves further study in prospective trials.

Autologous hematopoietic cell transplantation versus whole-brain radiotherapy consolidation in primary central nervous system lymphoma: A systematic review and meta-analysis

The management of newly diagnosed primary central nervous system lymphoma (PCNSL) includes administration of high-dose methotrexate based regimens followed by consolidation therapy to minimize the risk of relapse. However, the best consolidation strategy (autologous hematopoietic cell transplant [auto-HCT] vs. whole-brain radiotherapy [WBRT]) is controversial. Hence, we performed a systematic review and meta-analysis of all randomized controlled trials that compared auto-HCT versus WBRT consolidation for patients with PCNSL after first-line treatment.The primary outcome was overall survival (OS), while the secondary outcomes included progression-free survival (PFS), response rates (overall response rate [ORR] and complete remission [CR]), relapse rate, treatment-related mortality (TRM), and neuropsychological adverse events. We performed a pooled analysis of the single-arm studies that incorporated auto-HCT or WBRT consolidation and evaluated neurocognitive outcomes. Only two studies met the inclusion criteria (n = 240). There was no significant difference in OS (HR = 1.50; 95% CI = 0.95-2.36), PFS (HR = 0.99; 95% CI = 0.44-2.22), ORR (RR = 1.48; 95% CI = 0.90-2.44), CR rate (RR = 1.21; 95% CI = 0.90-1.63), relapse rate (RR = 0.46; 95% CI = 0.05-4.28), and TRM (RR = 5.67; 95% CI = 1.01-31.91). The neuropsychological tests to assess neurocognitive domains were different and inconsistently reported in the two studies and therefore we were unable to perform a meta-analysis but provide a descriptive assessment. Both the studies showed a significant decline in the attention/executive function (based on the trail making test A and trail making test B) in those receiving WBRT compared to auto-HCT. We found 9 single-arm phase II studies that reported data on outcomes associated with either auto-HCT (5 studies) or WBRT (4 studies) consolidation. Of these, two studies (n = 43) reported data on neurocognitive decline following auto-HCT consolidation. Pooled proportion of patients with neurocognitive decline in these studies was 6% (95% CI, 0%-17%) for those receiving auto-HCT and there was no heterogeneity between studies (I²  = 0%). Three studies (n = 122) reported data on neurocognitive decline following WBRT consolidation. Pooled proportion of patients with neurocognitive decline in these studies was 43% (95% CI, 11%-78%) for those receiving WBRT and there was high heterogeneity between studies (I²  = 94%). There was significant heterogeneity between subgroups (p = 0.035). The outcomes were not significantly different in patients with PCNSL receiving auto-HCT or WBRT consolidation therapies, however, there is a higher degree of neurocognitive decline associated with WBRT compared to auto-HCT consolidation. The decision to choose a consolidation strategy needs to be individualized based on age, frailty, and co-morbidities.

Safety and efficacy of high-dose cytarabine MEAM therapy and other treatments for auto-peripheral blood stem cell transplantation: A retrospective comparative study

AIM

The MEAM regimen consisting of ranimustine (MCNU), etoposide (ETP), cytarabine (Ara-C), and melphalan (MEL) is widely used before auto-peripheral blood stem cell transplantation (auto-PBSCT) for malignant lymphoma in Japan. The MEAM regimen generally consists of 200-400 mg/m² for 4 days, but we decided to increase the dosage of Ara-C from the standard to 2 g/m² for 2 days with the aim of increasing drug transferability to the central nervous system. We evaluate the safety and therapeutic efficacy of high-dose Ara-C MEAM therapy.

METHODS

The high-dose Ara-C MEAM protocol consisted of MCNU 300 mg/m² on day -7, ETP 200 mg/m² on days -6, -5, -4, -3 and Ara-C 2 g/m² on day -4 -3, and MEL 140 mg/m² on day -2. We retrospectively analyzed 37 cases of malignant lymphoma at our institution between May 2014 and July 2020.

RESULTS

All patients got engraftment and there were no cases of treatment-related mortality. In all cases, the 3-year overall survival (OS) and progression-free survival (PFS) after transplantation were 80.6% and 65.7%, respectively. Twenty-one cases of diffuse large B-cell lymphoma recurrence, for which there is proven usefulness of auto-PBSCT, showed good results after transplantation, with the 3-year OS and PFS after transplantation being 100% and 74.3%, respectively.

CONCLUSION

The safety and efficacy of high-dose Ara-C MEAM therapy were demonstrated, but the expected therapeutic effect on central nervous system lesions could not be fully evaluated owing to the small number of cases.

Diagnosis and Treatment Using Autologous Stem-Cell Transplantation in Primary Central Nervous System Lymphoma: A Systematic Review

BACKGROUND

Consolidation therapy has improved the outcome of newly diagnosed PCNSL patients. Whole-brain radiotherapy (WBRT) was the first consolidation strategy used and represented the gold standard for many years, but at the expense of a high risk of neurotoxicity. Thus, alternative strategies are being investigated in order to improve disease outcomes and to spare the neurocognitive side effects due to WBRT.

METHODS

We reviewed published studies on PCNSL patients treated with HDC/ASCT, focusing on the efficacy and safety of the conditioning regimens. Prospective and retrospective studies, published in the English language from 1992 to 2022, in high-quality international journals were identified in PubMed.

RESULTS

Consolidation with HDC containing highly CNS-penetrating agents (thiotepa, busulfan or BCNU) followed by ASCT provided long-term disease control and survival in PCNSL patients. Two prospective randomized studies, comparing HDC/ASCT versus WBRT, reported similar progression-free survival (PFS) and similar results on the decline in neurocognitive functions in a substantial proportion of patients after WBRT but not after HDC-ASCT. A recent randomized study comparing HDC/ASCT versus non-myeloablative consolidation reported a longer PFS in transplanted patients.

CONCLUSION

ASCT conditioned with regimens, including highly CNS-penetrating agents, represents, to date, the best choice among the available consolidation strategies for fit newly diagnosed PCNSL patients.

European Association of Neuro-Oncology (EANO) guidelines for treatment of primary central nervous system lymphoma (PCNSL)

The management of primary central nervous system (PCNSL) is one of the most controversial topics in neuro-oncology because of the complexity of the disease and the limited number of controlled studies available. In 2021, given recent advances and the publication of practice-changing randomized trials, the European Association of Neuro-Oncology (EANO) created a multidisciplinary task force to update the previously published evidence-based guidelines for immunocompetent adult patients with PCNSL and added a section on immunosuppressed patients. The guideline provides consensus considerations and recommendations for the treatment of PCNSL, including intraocular manifestations and specific management of the elderly. The main changes from the previous guideline include strengthened evidence for the consolidation with ASCT in first-line treatment, prospectively assessed chemotherapy combinations for both young and elderly patients, clarification of the role of rituximab even though the data remain inconclusive, of the role of new agents, and the incorporation of immunosuppressed patients and primary ocular lymphoma. The guideline should aid the clinicians in everyday practice and decision making and serve as a basis for future research in the field.

Treatment Options for Recurrent Primary CNS Lymphoma

OPINION STATEMENT

Primary CNS lymphoma (PCNSL) constitutes a rare extranodal variant of non-Hodgkin lymphoma (NHL) with an annual incidence of 0.45/100,000. Given the paucity of large prospective clinical trials, there is no consensus treatment for refractory or relapsed (r/r) PCNSL, and available strategies are largely based on retrospective analyses. Patient age, performance status, previously administered treatment, duration of response, and molecular characteristics guide selection of salvage therapy. Patients with a good performance status (KPS >70), particularly ≤65 years, and adequate organ function should be considered for salvage polychemotherapy. Based on its high overall response rate even in the relapsed setting, we choose high-dose (≥ 3.5g/m²) methotrexate (HD-MTX) based regimens, e.g., R-MPV (rituximab, HD-MTX, procarbazine, and vincristine), for remission re-induction as long as patients were sensitive to first line HD-MTX-based regimens, especially when duration of previous response was ≥ 1 year. Following successful remission induction, we choose myeloablative chemotherapy (e.g., thiotepa, busulfan, cyclophosphamide) and subsequent autologous stem cell transplant in curative intent whenever feasible. Alternatively, conventional chemotherapy regimens (for example, monthly HD-MTX) or low-dose whole-brain radiation therapy (WBRT) are selected for consolidation in non-transplant candidates in complete remission. In cases of HD-MTX refractory disease or contraindications, we use pemetrexed; temozolomide/rituximab; high-dose cytarabine; or whole brain radiation for remission induction. Clinical trial participation is considered as well. Emerging therapies for upfront or salvage therapy under ongoing investigation include bruton tyrosine kinase inhibition (e.g., ibrutinib), immunomodulatory drugs (e.g., lenalidomide), immune checkpoint inhibitors (ICI, e.g., nivolumab), and chimeric antigen receptor T (CAR-T) cell therapy.

Prognostic factors in primary central nervous system lymphoma

PURPOSE OF REVIEW

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive extranodal diffuse large B cell lymphoma. Despite its apparent immunopathological homogeneity, PCNSL displays a wide variability in outcome. Identifying prognostic factors is of importance for patient stratification and clinical decision-making. The purpose of this review is to focus on the clinical, neuroradiological and biological variables correlated with the prognosis at the time of diagnosis in immunocompetent patients.

RECENT FINDINGS

Age and performance status remain the most consistent clinical prognostic factors. The current literature suggests that neurocognitive dysfunction is an independent predictor of poor outcome. Cumulating data support the prognostic value of increased interleukin-10 level in the cerebrospinal fluid (CSF), in addition to its interest as a diagnostic biomarker. Advances in neuroimaging and in omics have identified several semi-quantitative radiological features (apparent diffusion restriction measures, dynamic contrast-enhanced perfusion MRI (pMRI) pattern and 18F-fluorodeoxyglucose metabolism) and molecular genetic alterations with prognostic impact in PCNSL.

SUMMARY

Validation of new biologic and neuroimaging markers in prospective studies is required before integrating future prognostic scoring systems. In the era of radiomic, large clinicoradiological and molecular databases are needed to develop multimodal artificial intelligence algorithms for the prediction of accurate outcome.

Optimizing MATRix as remission induction in PCNSL: de-escalated induction treatment in newly diagnosed primary CNS lymphoma

BACKGROUND

Primary diffuse large B-cell lymphoma (DLBCL) of the central nervous system (PCNSL) is a rare disorder with an increasing incidence over the past decades. High-level evidence has been reported for the MATRix regimen (high-dose methotrexate (HD-MTX), high-dose AraC (HD-AraC), thiotepa and rituximab) followed by high-dose chemotherapy and autologous stem cell transplantation (HCT-ASCT) supporting this approach to be considered a standard therapy in newly diagnosed PCNSL patients ≤ 70 years. However, early treatment-related toxicities (predominantly infectious complications), occurring in up to 28% per MATRix cycle, diminish its therapeutic success. Furthermore, sensitivity to first-line treatment is an independent prognostic factor for improved overall survival (OS) in PCNSL. Thus, patients achieving early partial remission (PR) after 2 cycles of MATRix might be over-treated with 4 cycles, in the context of consolidation HCT-ASCT.

METHODS

This is an open-label, multicentre, randomized phase III trial with two parallel arms. 326 immunocompetent patients with newly diagnosed PCNSL will be recruited from 37 German, 1 Austrian and 12 UK sites. Additional IELSG (International Extranodal Lymphoma Study Group) sites are planned. The objective is to demonstrate superiority of a de-escalated and optimised remission induction treatment strategy, followed by HCT-ASCT. Randomization (1:1) will be performed after completion of all screening procedures. Patients in Arm A (control treatment) will receive 4 cycles of MATRix. Patients in Arm B (experimental treatment) will receive a pre-phase (R/HD-MTX), followed by 2 cycles of MATRix. Patients in both arms achieving PR or better will proceed to HCT-ASCT (BCNU, thiotepa). The primary endpoint of the study is event-free-survival (EFS), defined as time from randomization to premature end of treatment due to any reason, lymphoma progression or death whichever occurs first. Secondary endpoints include OS, progression free survival (PFS), toxicity, neurocognitive impairment and quality of life. Minimal follow-up is 24 months.

DISCUSSION

Current treatment options for PCNSL in patients ≤ 70 years have improved remarkably over recent years. However, the potential efficacy benefits are offset by an increased incidence of short-term toxicities which can impact on treatment delivery and hence on survival outcomes. In patients ≤ 70 years with newly diagnosed PCNSL addressing the need to reduce treatment-related toxicity by de-escalating and optimising the induction phase of treatment, is a potentially attractive treatment strategy.

TRIAL REGISTRATION

German clinical trials registry DRKS00022768 registered June 10th, 2021.

A Retrospective Analysis of R-MPV Plus Response-adapted Whole-brain Radiotherapy for Elderly Patients with Primary Central Nervous System Lymphoma

Objective Few reports have described the real-world outcomes of rituximab, methotrexate (MTX), procarbazine, and vincristine (R-MPV) plus response-adapted whole-brain radiotherapy (WBRT) for elderly patients with primary central nervous system lymphoma (PCNSL). We evaluated the outcome of this regimen. Methods We evaluated >60-year-old patients with newly diagnosed PCNSL who received R-MPV plus WBRT from January 2010 to December 2019 at Toyohashi Municipal Hospital. The patients' characteristics, regimen enforcement, response rate, survival, and toxicity were analyzed. Patients Ten patients were consecutively enrolled. Their median age was 69 years old, and 60% had a performance status of 3 or 4 before induction therapy. Results Seven patients achieved a complete response after induction, and all 10 patients achieved a complete response after consolidation. Seven received reduced-dose WBRT at 23.4 Gy, and 2 received WBRT at 45 Gy. The median follow-up was 44.4 months; the 3-year progression-free survival and overall survival rates were 60% and 80%, respectively; and the cumulative incidence of relapse was 40%. The incidence of symptomatic delayed neurotoxicity was 70%. Of the 7 patients who received reduced-dose WBRT, 4 (57%) developed delayed neurotoxicity, including 1 severely affected patient. Only one patient survived without relapse and delayed neurotoxicity. The ratio of patients who developed relapse or delayed neurotoxicity that impaired daily life was 33% and 100% in the MTX high- and low-intensity groups, respectively. Conclusion This regimen in elderly patients is unsatisfactory because of delayed neurotoxicity. We should consider maintaining an adequate MTX intensity, postponing or minimizing WBRT, and choosing high-dose consolidation therapy for select patients.

High-Dose Chemotherapy with Autologous Hematopoietic Stem Cell Transplantation in Relapsed or Refractory Primary CNS Lymphoma: A Retrospective Monocentric Analysis of Long-Term Outcome, Prognostic Factors, and Toxicity

High-dose chemotherapy with autologous stem cell transplantation (HCT-ASCT) is reportedly an effective treatment strategy in relapsed or refractory primary CNS lymphoma (r/r PCNSL); however, only selected patients are eligible for this treatment. We retrospectively analyzed outcome, prognostic factors, and toxicity in 59 patients with r/r PCNSL planned to receive HCT-ASCT at our institution between January 2005 and December 2021 (n = 33 < 65 years; n = 26 ≥ 65 years). Median follow-up was 65 months (95% CI 21−109). Median age was 63 years (range 29−76), median Karnofsky performance score (KPS) was 80 (range 30−100). In the entire cohort of 59 patients, median overall survival (OS) was 14 months (95% CI 0−37). In 50/59 (84.7%) patients who completed HCT-ASCT, median progression free survival (PFS) was 12 months (95% CI 3−21) and median OS 30 months (95% CI 0−87). 1-year, 2-year, and 5-year OS rates of 61.2%, 52.3% and 47.1%, respectively, were observed. Six patients (10.2%) died related to treatment (1 during induction treatment, 5 post HCT-ASCT). Age was not prognostic. On univariate analysis, KPS ≥ 80 (p = 0.019) and complete or partial remission before HCT-ASCT (p = 0.026) were positive prognosticators of OS; on multivariate analysis, KPS (p = 0.043) and male gender (p = 0.039) had an impact on OS. The 5-year OS rate in patients with progressive or stable disease after induction treatment was 32.7%. In summary, HCT-ASCT was effective and feasible in this cohort of r/r PCNSL patients. Clinical state, remission status before HCT-ASCT, and gender influenced survival, whereas age did not influence outcome in this study.

Efficacy and Safety of Autologous Stem-Cell Transplantation as Part of First-Line Treatment for Newly Diagnosed Primary Central Nervous System Lymphoma: A Systematic Review and Meta-Analysis

Objective

The reviewed literature supports a treatment regimen for primary central nervous system lymphoma (PCNSL) that includes induction chemotherapy, followed by one consolidation therapy. High-dose chemotherapy supported by autologous stem-cell transplantation (ASCT) is the most studied option, but its effects are controversial. The aim of this study was to evaluate the efficacy and safety of ASCT for newly diagnosed PCNSL by means of a meta-analysis.

Methods

The PubMed, Embase, and Cochrane Library databases were systematically searched for studies published until May 20, 2021. Included studies were prospective studies of patients with newly diagnosed PCNSL treated with ASCT. The pooled rates and 95% confidence intervals (CIs) were determined for all outcomes. Subgroup analysis was conducted to compare the relative risk (RR) with 95% CIs for the complete remission (CR) rate and the hazard ratios (HRs) with 95% CIs for progression-free survival (PFS) and overall survival (OS).

Results

Thirteen prospective studies including 348 patients were analyzed. The pooled CR rate, overall response rate, and relapse rate were 80% (95% CI, 71–88%, I² = 67.06%, p = 0.00), 95% (95% CI, 87–100%, I² = 73.65%, p= 0.00), and 19% (95% CI, 15–24%, I² = 76.18%, p = 0.00), respectively. The pooled 2- and 5-year PFS and OS rates were 74% (95% CI, 68–80%, I² = 3.90%), 65% (95% CI, 51–77%, I² = 74.61%), 80% (95% CI, 72–88%, I² = 57.54%), and 69% (95% CI, 53–83%, I² = 83.89%), respectively. Hematological toxicity and infections were more common adverse events above grade 3. The pooled treatment-related mortality was 3% (95% CI, 1–6%, I² = 28.18%, p = 0.16). In the group analysis of ASCT compared with whole-brain radiotherapy, there were no significant differences in the CR rate (RR, 1.00, 95% CI, 0.88–1.14, p = 0.971), relapse rate (RR, 0.44, 95% CI, 0.06–3.10, p = 0.408), PFS (HR, 1.28, 95% CI, 0.81–2.01, p = 0.29), or OS (HR, 1.62, 95% CI, 0.97–2.69, p = 0.06). Cognitive functions were preserved or improved after ASCT.

Conclusions

ASCT is a feasible approach for consolidation with good tolerability for newly diagnosed PCNSL patients. High-quality randomized controlled trials are still needed to confirm the effects of ASCT.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42021268422.

A narrative review of consolidation strategies for young and fit patients with newly-diagnosed primary central nervous system lymphoma

INTRODUCTION

The modern treatment of patients with primary central nervous system lymphoma (PCNSL) consists of two phases: induction, currently represented by a high-dose-methotrexate-based polychemotherapy, and consolidation. The optimal consolidation therapy has not been defined yet, but several strategies, such as whole-brain radiotherapy (WBRT), high-dose chemotherapy supported by autologous stem cell transplantation (HDC/ASCT) or non-myeloablative chemotherapy, have been addressed in important randomized trials.

AREAS COVERED

This review provides an overview of the current role of consolidation strategies in young and fit patients with newly-diagnosed PCNSL. Publications in English language, peer-reviewed, from high-quality international journals, edited from 2003 to 2021 were identified on PubMed.

EXPERT OPINION

Consolidation treatment significantly improved outcomes of PCNSL. Radiotherapy had represented for years the only choice in the consolidation therapy, but large randomized trials have demonstrated that HDC/ASCT is equally effective and associated with lower neurotoxicity risk in patients younger than 65-70 years. Encouraging results have been obtained using reduced-dose WBRT, while a recent randomized trial failed to demonstrate that consolidation with non-myeloablative chemotherapy is more effective than HDC/ASCT in PCNSL patients. A personalized consolidation treatment, driven also by a response prediction model based on radiological and molecular details, may improve the management of PCNSL patients.

Treatment of Primary CNS Lymphoma: Maximizing Clinical Benefit, Minimizing Neurotoxicity

PURPOSE OF REVIEW

The optimal treatment for newly diagnosed and refractory or relapsed primary central nervous system lymphoma (PCNSL) is not fully defined. We review the epidemiology, clinical presentation, and current management strategies for newly diagnosed PCNSL as well as emerging treatments for refractory and relapsed disease.

RECENT FINDINGS

In recent decades, the incidence of PCNSL has increased in the elderly population. With advancements in chemotherapy for PCNSL, survival has improved. However, outcomes remain inferior when compared with other forms of extranodal lymphoma. Additionally, treatments can be associated with clinically significant neurotoxicities. Despite advances in the treatment of PCNSL, current treatment regimens remain suboptimal in terms of response rates and neurotoxicity. Well-tolerated agents, especially for the elderly, are still needed.

Treatment Regimens for Immunocompetent Elderly Patients with Primary Central Nervous System Lymphoma: A Scoping Review

Simple Summary

Most patients diagnosed with primary central nervous system lymphoma (PCNSL) are 60 years or older and tend to have a poor prognosis. Evidence to guide and optimize treatment choices for these vulnerable patients is limited. We performed a scoping review to identify and describe all relevant clinical studies investigating chemotherapies and combinations of chemotherapies (including high-dose chemotherapy followed by autologous stem cell transplantation (HCT-ASCT)) in elderly PCNSL patients. In total, we identified six randomized controlled trials, 26 prospective and 24 retrospective studies (with/without control group). While most studies investigated protocols based on ‘conventional’ chemotherapy treatment, data evaluating HCT-ASCT in the elderly were scarce, and the generalizability of the only RCT published is questionable. Considering the poor prognosis of these patients and their need for more effective treatment options, a thoroughly planned randomized controlled trial comparing HCT-ASCT with ‘conventional’ chemoimmunotherapy is urgently needed to evaluate the efficacy of HCT-ASCT.

Abstract

Background: Most patients diagnosed with primary central nervous system lymphoma (PCNSL) are older than 60 years. Despite promising treatment options for younger patients, prognosis for the elderly remains poor and efficacy of available treatment options is limited. Materials and Methods: We conducted a scoping review to identify and summarize the current study pool available evaluating different types and combinations of (immuno) chemotherapy with a special focus on HCT-ASCT in elderly PCNSL. Relevant studies were identified through systematic searches in the bibliographic databases Medline, Web of Science, Cochrane Library and ScienceDirect (last search conducted in September 2020). For ongoing studies, we searched ClinicalTrials.gov, the German study register and the WHO registry. Results: In total, we identified six randomized controlled trials (RCT) with 1.346 patients, 26 prospective (with 1.366 patients) and 24 retrospective studies (with 2.629 patients). Of these, only six studies (one completed and one ongoing RCT (with 447 patients), one completed and one ongoing prospective single arm study (with 65 patients), and two retrospective single arm studies (with 122 patients)) evaluated HCT-ASCT. Patient relevant outcomes such as progression-free and overall survival and (neuro-)toxicity were adequately considered across almost all studies. The current study pool is, however, not conclusive in terms of the most effective treatment options for elderly. Main limitations were (very) small sample sizes and heterogeneous patient populations in terms of age ranges (particularly in RCTs) limiting the applicability of the results to the target population (elderly). Conclusions: Although it has been shown that HCT-ASCT is probably a feasible and effective treatment option, this approach has never been investigated within a RCT including a wide range of elderly patients. A RCT comparing conventional (immuno) chemotherapy with HCT-ASCT is crucial to evaluate benefit and harms in an un-biased manner to eventually provide older PCNSL patients with the most effective treatment.

Primary Central Nervous System Lymphoma in Elderly Patients: Management and Perspectives

The management of elderly patients suffering from primary central nervous system (CNS) lymphoma, who represent a rapidly growing population, is challenging. Despite the advances made in PCNSL treatment, the prognosis in older patients remains unsatisfactory. The high risk of systemic and CNS toxicity induced by a high-dose chemotherapy regimen and radiation therapy, respectively, limits the use of consolidation phase treatments in elderly patients and contributes to the poor outcome of these patients. Here, we review the current treatment strategies and ongoing trials proposed for elderly PCNSL patients.

Outcomes Associated With Thiotepa-Based Conditioning in Patients With Primary Central Nervous System Lymphoma After Autologous Hematopoietic Cell Transplant

Importance

Primary central nervous system lymphoma (PCNSL) requires induction and consolidation to achieve potential cure. High-dose therapy and autologous hematopoietic cell transplant (AHCT) is an accepted and effective consolidation strategy for PCNSL, but no consensus exists on the optimal conditioning regimens.

Objective

To assess the outcomes in patients with PCNSL undergoing AHCT with the 3 most commonly used conditioning regimens: thiotepa/busulfan/cyclophosphamide (TBC), thiotepa/carmustine (TT-BCNU), and carmustine/etoposide/cytarabine/melphalan (BEAM).

Design, Setting, and Participants

This observational cohort study used registry data from the Center for International Blood and Marrow Transplant Research registry. The Center is a working group of more than 380 transplantation centers worldwide that contributed detailed data on HCT to a statistical center at the Medical College of Wisconsin, Milwaukee. The participant data were from 603 adult patients with PCNSL who underwent AHCT as initial, or subsequent, consolidation between January 2010 and December 2018. Patients were excluded if they had a non-Hodgkin lymphoma subtype other than diffuse large B-cell lymphoma, systemic non-Hodgkin lymphoma, or HIV; received an uncommon conditioning regimen; or were not in partial remission or complete remission prior to AHCT. Statistical analysis was performed from July 5, 2020, to March 1, 2021.

Interventions

Patients received 1 of 3 conditioning regimens: TBC (n = 263), TT-BCNU (n = 275), and BEAM (n = 65).

Main Outcomes and Measures

The primary outcome was progression-free survival. Secondary outcomes included hematopoietic recovery, incidence of relapse, nonrelapse mortality, and overall survival.

Results

Of 603 patients, the mean age was 57 (range, 19-77) years and 318 (53%) were male. The 3-year adjusted progression-free survival rates were higher in the TBC cohort (75%) and TT-BCNU cohort (76%) compared with the BEAM cohort (58%) (P = .03) owing to a higher relapse risk in the BEAM cohort (hazard ratio [HR], 4.34; 95% CI, 2.45-7.70; P < .001). In a multivariable regression analysis, compared with the TBC cohort, patients who received TT-BCNU had a higher relapse risk (HR, 1.79; 95% CI, 1.07-2.98; P = .03), lower risk of nonrelapse mortality (NRM) (HR, 0.50; 95% CI, 0.29-0.87; P = .01), and similar risk of all-cause mortality more than 6 months after HCT (HR, 1.54; 95% CI, 0.93-2.55; P = .10). Age of 60 years or older, Karnofsky performance status less than 90, and an HCT-comorbidity index greater than or equal to 3 were associated with lower rates of survival across all 3 cohorts. Subgroup analyses demonstrated that patients aged 60 years and older had considerably higher NRM with TBC.

Conclusions and Relevance

In this cohort study, thiotepa-based conditioning regimen was associated with higher rates of survival compared with BEAM, despite higher rates of early toxic effects and NRM; these findings may assist clinicians in choosing between TBC or TT-BCNU based on patient and disease characteristics.

Primary central nervous system lymphoma: a narrative review of ongoing clinical trials and goals for future studies

Primary central nervous system lymphoma (PCNSL) is a rare disease of the brain, spine, cerebrospinal fluid (CSF) and/or vitreoretinal space. PCNSL is chemo and radiosensitive but relapse is common even years after initial treatment. Outside of consensus regarding the use of high-dose methotrexate (HD-MTX) for first line treatment, there is little uniformity in the management of newly diagnosed or relapsed PCNSL. The lack of consensus is driven by a paucity of randomized trials in this disease. Prospective studies are troubled by low enrollment, the lack of a standard induction regimen, and a varied approach to consolidation strategies. Moreover, the PCNSL patient population is heterogeneous and includes a high proportion of elderly or frail patients and consists of patients manifesting disease in varied compartments of the central nervous system (CNS). As a result, current treatment strategies vary widely and are often dictated by physician and institutional preference or regional practice. This review provides an overview of recently completed and ongoing therapeutic studies for patients with newly diagnosed and recurrent or refractory PCNSL. It discusses the existing evidence behind common approaches to induction and consolidation or maintenance regimens as well as the recent data regarding management of recurrent disease. Finally, it highlights the complexity of trial design in this disease and provides a framework for the design of future studies, which are needed to identify patient populations likely to benefit from specific induction, consolidation, or maintenance therapies.