Reduced-dose whole-brain radiotherapy with tumor bed boost after upfront high-dose methotrexate for primary central nervous system lymphoma

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.

The role of radiotherapy in newly diagnosed primary CNS lymphoma: A descriptive review and a pragmatic approach to clinical practice

Earlier, prior to the development of effective systemic therapy, monotherapy with whole-brain radiotherapy (WBRT) was widely used to treat primary central nervous system lymphoma (PCNSL). Recently, chemotherapy, especially with high dose methotrexate (HDMTX), has largely replaced WBRT as upfront treatment, and the most accepted standard of care is induction with a combination drug therapy followed by consolidation therapy with either autologous stem-cell transplantation (ASCT) or radiation. Whilst WBRT is an effective component of treatment, it is occasionally associated with risk of permanent, irreversible neurotoxicity when doses of more than 30 Gy are used. Hence, there has been a strong focus on the optimization of radiotherapy (RT) which includes dose reduction in the consolidation phase. In this comprehensive review, we have summarized the progress on clinical results and evidence considering the role and use of radiation including combined treatment modalities, low-dose radiotherapy, and neurotoxicity. Finally, we present a practical approach to low-dose WBRT and boosting higher doses to the gross tumor that can be integrated into clinical practice.

Evidence-based expert consensus on the management of primary central nervous system lymphoma in China

Primary central nervous system lymphoma (PCNSL) is a type of central nervous system restricted non-Hodgkin lymphoma, whose histopathological diagnosis is majorly large B cell lymphoma. To provide specific, evidence-based recommendations for medical professionals and to promote more standardized, effective and safe treatment for patients with PCNSL, a panel of experts from the Chinese Neurosurgical Society of the Chinese Medical Association and the Society of Hematological Malignancies of the Chinese Anti-Cancer Association jointly developed an evidence-based consensus. After comprehensively searching literature and conducting systematic reviews, two rounds of Delphi were conducted to reach consensus on the recommendations as follows: The histopathological specimens of PCNSL patients should be obtained as safely and comprehensively as possible by multimodal tomography-guided biopsy or minimally invasive surgery. Corticosteroids should be withdrawn from, or not be administered to, patients with suspected PCNSL before biopsy if the patient's status permits. MRI (enhanced and DWI) should be performed for diagnosing and evaluating PCNSL patients where whole-body PET-CT be used at necessary time points. Mini-mental status examination can be used to assess cognitive function in the clinical management. Newly diagnosed PCNSL patients should be treated with combined high-dose methotrexate-based regimen and can be treated with a rituximab-inclusive regimen at induction therapy. Autologous stem cell transplantation can be used as a consolidation therapy. Refractory or relapsed PCNSL patients can be treated with ibrutinib with or without high-dose chemotherapy as re-induction therapy. Stereotactic radiosurgery can be used for PCNSL patients with a limited recurrent lesion who were refractory to chemotherapy and have previously received whole-brain radiotherapy. Patients with suspected primary vitreoretinal lymphoma (PVRL) should be diagnosed by vitreous biopsy. PVRL or PCNSL patients with concurrent VRL can be treated with combined systemic and local therapy.

Reduced-dose WBRT as consolidation treatment for patients with primary CNS lymphoma: a LOC-network study

After consolidation rdWBRT in a subset of patients, most of the patients exhibited sustained or improved cognitive function.

rdWBRT should be considered a strong consolidation treatment for PCNSL in patients aged <60 years showing CR after induction chemotherapy.

The optimal consolidation strategy for primary central nervous system lymphoma (PCNSL) remains controversial. Preventing radio-induced neurotoxicity of consolidation treatment through reduced-dose whole-brain radiotherapy (rdWBRT) at a dose of 23.4 Gy is an interesting alternative to conventional WBRT in patients aged <60 years. From the LOC Network (Network for Oculo-cerebral Lymphomas) database, we retrospectively selected patients with PCNSL aged <60 years who showed complete (CR) or unconfirmed CR after high-dose methotrexate–based chemotherapy and had received consolidation rdWBRT as the first-line treatment. If available, prospective neuropsychological follow-ups were reported. Twenty-nine patients diagnosed between 2013 and 2018 met the study selection criteria. Nine (31%) patients experienced relapse during the follow-up, with a median time from radiotherapy to recurrence of 8.7 months (interquartile range, 4-11.5). Five of those patients received salvage treatment and consolidation with intensive chemotherapy and autologous stem cell transplantation. Progression-free survival rates were 89% (95% confidence interval [CI] 79%-100%), 72% (95% CI, 56%-88%), and 69% (95% CI, 52%-85%) at 1, 2, and 5 years, respectively. Overall survival rates were 100%, 89% (95% CI, 79%-100%), and 86% (95% CI, 74%-99%) at 1, 2, and 5 years, respectively, and were consistent with those observed for standard-dose WBRT (sdWBRT). No prognostic factor was identified. The results of the 36-month neuropsychological follow-up for a subset of patients appeared reassuring, with most patients exhibiting maintenance of or improvements in their baseline conditions. Our results, combined with phase 2 study results, support the use of rdWBRT instead of sdWBRT as a consolidation treatment in <60-year-old patients showing CR after induction treatment.

Central Nervous System Lymphoma: Novel Therapies

OPINION STATEMENT

Primary central nervous system lymphomas (PCNSLs) are very rare neoplasms and continue to be challenging to treat. While high-dose methotrexate (HD-MTX)-based regimens are the currently accepted standard first-line therapy for newly diagnosed patients, the optimal induction therapies are still unknown. The role of consolidation therapies continues to evolve with a variety of chemotherapy regimens, including high-dose chemotherapy with stem cell rescue and reduced or deferred whole brain radiotherapy being used. Importantly, several recent advances have been made in the treatment of PCNSL. The incorporation of targeted therapy and immune therapy remain promising strategies. Several agents, successfully used in treatment of systemic lymphomas, have shown activity in PCNSL, frequently leading to durable responses in the relapsed/refractory patients. Many ongoing studies will likely lead to a better understanding of the roles of these treatments, especially as the first line and potentially also as maintenance. In addition, the use of molecular profiling to predict disease response to targeted agents and understand relapse patterns will become increasingly important. Clinical trials in PCNSL are critical yet frequently challenging to conduct given the rarity of the condition and lack of suitable subjects. Therefore, multi-institutional and international collaboration is of utmost importance to accelerate progress in understanding the biology and design better treatments for this disease. It is critical to consider patients of all demographics in the design and study of future treatment algorithms to have the largest impact on patient care and outcomes.

Selective salvage radiotherapy could provide favorable outcomes in patients with refractory or relapsed primary central nervous system lymphoma

INTRODUCTION

To date, there is no relevant data supporting the role of salvage radiotherapy (sRT) in patients with refractory or relapsed primary central nervous system lymphoma (PCNSL). Herein, we aimed to investigate the impact of sRT in patients with refractory or relapsed PCNSL following upfront HD-MTX.

METHODS

We retrospectively reviewed 89 patients who had refractory (n = 16) or recurrent disease after an initial favorable response (n = 73); among them, 41 were treated with sRT and 48 were treated without sRT (nRT). Event-free survival (rEFS) and overall survival (rOS) after first recurrence were considered from the date of recurrence to date of each event.

RESULTS

Overall, the first failure was diagnosed at a median of 11.0 months [interquartile range (IQR), 5.6-26.4] after first treatment. More than half of the patients had recurrent disease involving initial tumor bed (n = 47), deep structure (n = 67), and multiple lesions (n = 58). Among 19 patients who were initially treated with 23.4 Gy of whole brain RT, 10 patients received sRT as a re-irradiation; other 31 patients in sRT group were RT naïve patients. There was no significant difference in tumor characteristics between sRT and nRT group. Overall and complete response after salvage treatment were 80% and 48%, respectively; sRT provided higher overall response rate than nRT (93% vs. 69%, p = 0.011). With a median follow-up of 14.3 months (IQR, 7.9-31.4), 2-year rEFS and rOS rates were 27% and 57%, respectively. There were no differences in rEFS and rOS according to sRT (sRT vs. nRT, 26% vs. 28%, p = 0.730; 63% vs. 50%, p = 0.690). Poor performance, recurrence interval < 8 months, and unfavorable response following salvage treatment were associated with inferior rEFS and rOS. Additionally, sRT and stem cell transplantation improved response rate independently after multivariate analysis for complete/partial response.

CONCLUSIONS

We found favorable response rate and comparable survival outcomes following sRT compared with non-local treatments for patients with refractory/relapsed PCNSL. Further studies of patient selection could stratify patients who can benefit from sRT.

Advances in treatment of elderly primary central nervous system lymphoma

The management of older individuals (≥60 years) with primary central nervous system lymphoma remains a clinical challenge. Identification of optimal therapy and delivering adequate dose intensity are two of the major issues in treating elderly patients. Premorbid performance status and comorbidities influence individualised treatment approaches and geriatric assessment tools are increasingly utilised. Optimal induction treatment remains high-dose methotrexate-based immunochemotherapy, delivery is feasible in the majority of patients and the goal of treatment remains achieving complete remission. Consolidation strategies are also relevant in the elderly, aiming to maximise duration of response and quality of life (QoL). Potential options include high-dose therapy with haematopoietic stem cell consolidation, non-myeloablative chemotherapy and whole-brain radiotherapy. Efficacy of novel agents, such as Bruton tyrosine kinase inhibitors and lenalidomide, have been reported; these represent an alternative for elderly patients unfit for chemotherapy. Prognosis remains poor, improvement of outcomes in this age group is urgently needed.

Role of 23.4 Gy upfront whole-brain radiation therapy following high-dose methotrexate for primary central nervous system lymphoma: a comparative analysis of whole-brain radiation therapy versus no radiation therapy

INTRODUCTION

We aimed to investigate the role of upfront whole-brain radiation therapy (RT), with a reduced dose of 23.4 Gy, following high-dose methotrexate (HD-MTX) in patients with primary central nervous system lymphoma (PCNSL).

METHODS

We retrospectively reviewed 185 patients with PCNSL treated with HD-MTX between January 2013 and January 2020; 145 patients underwent no RT and 40 patients underwent upfront RT. Using propensity score matching (PSM) to adjust for clinical factors, 40 patients were selected from each treatment group. Event-free survival (EFS) and overall survival (OS) were compared between treatment groups.

RESULTS

At baseline, patients in the upfront RT group were younger, had higher LDH levels, received less frequent rituximab and stem cell transplantation than those in the no-RT group. Patients in the upfront RT group also showed a lower response rate after initial HD-MTX than those in the no-RT group (73% vs. 88%, p = 0.038). The median follow-up was 25.1 (interquartile range 13.7-43.0) months. Comparable 2-year EFS and OS rates were observed between the upfront RT and no-RT groups (56.6% vs. 53.8%, p = 0.170; and 81.7% vs. 75.3%, p = 0.097, respectively). Upfront RT was related to improved EFS and OS in patients with stable disease or progressive disease after HD-MTX, but not in patients with complete or partial response after HD-MTX. Upfront RT was also an independent predictor of EFS and OS in the PSM cohort. The cumulative incidences of treatment-related neurotoxicity at 3 years were 20.2% and 21.2% in the upfront RT and no-RT groups, respectively (p = 0.630).

CONCLUSIONS

Upfront RT with a reduced dose of 23.4 Gy, showed favorable outcomes in patients with stable disease or progressive disease after initial HD-MTX. In addition, upfront RT appears to be an effective treatment for PCNSL when rituximab or stem cell transplantation is not feasible.

Is There an Indication for First Line Radiotherapy in Primary CNS Lymphoma?

Background: Primary CNS Lymphoma is a rare and severe but potentially curable disease. In the last thirty years treatment has changed significantly. Survival times increased due to high-dose methotrexate-based chemotherapy. With intensive regimens involving autologous stem cell transplantation (ASCT), 4-year survival rates of more than 80% can be reached. However, this treatment regimen is not feasible in all patients, and is associated with some mortality. Methods: In this review, current evidence regarding the efficacy and toxicity of radiotherapy in PCNSL shall be summarized and discussed mainly based on data of controlled trials. Results: Being the first feasible treatment whole brain radiotherapy (WBRT) was initially used alone, and later as a consolidating treatment after high-dose methotrexate-based chemotherapy. More recently, concerns regarding activity and neurotoxicity of standard dose WBRT limited its use. On the contrary, latest evidence of some phase II trials suggests efficacy of consolidating WBRT is comparable to ASCT. After complete remission reduced dose WBRT appears as a feasible concept with decreased neurotoxicity. Evidence for use of local stereotactic radiotherapy is very limited. Conclusion: Radiotherapy has a role in the treatment of PCNSL patients not suitable to ASCT, e.g., as consolidating reduced dose WBRT after complete response. Local stereotactic radiotherapy for residual disease should be examined in future trials.

Diagnosis, prognosis and treatment of primary central nervous system lymphoma in the elderly population (Review)

Primary central nervous system lymphoma (PCNSL) is a rare subtype of extranodal non-Hodgkin lymphoma that is unique and different from systemic diffuse large B-cell lymphomas. The median age at diagnosis of PCNSL is 65 years and its incidence is rising rapidly in the elderly population. A total of ≥20% of all patients with PCNSL are ≥80 years old. Notably, age has been identified as an independent poor prognostic factor for PCNSL. Elderly patients have an inferior prognosis to that of younger patients and are more severely affected by iatrogenic toxicity; therefore, elderly patients represent a unique and vulnerable treatment subgroup. The present review summarized the available literature to provide an improved understanding of the epidemiology, clinical characteristics, diagnosis, prognosis and management of PCNSL in the elderly population. Notably, the incidence of PCNSL in immunocompetent elderly patients, predominantly in men, is increasing. For the diagnosis of CNSL, imaging-guided stereotactic biopsy is considered the gold standard. When stereotactic biopsy is not possible or conclusive, certain biomarkers have been described that can help establish a diagnosis. PCNSL has a very poor prognosis in the elderly, even though several prognostic scoring systems exist and several prognostic markers have been reported in patients with PCNSL. Furthermore, the treatment of elderly patients remains challenging; it is unlikely that a novel agent could be used as a curative monotherapy; however, a combination of novel agents with polychemotherapy or its combination with other novel drugs may have therapeutic potential.