Study of radiolabeled indium-111 and yttrium-90 ibritumomab tiuxetan in primary central nervous system lymphoma

Targets and treatments in primary CNS lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare and highly aggressive lymphoma entirely localized in the central nervous system or vitreoretinal space. PCNSL generally initially responds to methotrexate-containing chemotherapy regimens, but progressive or relapsing disease is common, and the prognosis is poor for relapsed or refractory (R/R) patients. PCNSL is often characterized by activation of nuclear factor kappa B (NF-κB) due to mutations in the B-cell receptor (BCR) or toll-like receptor (TLR) pathways, as well as immune evasion. Targeted treatments that inhibit key PCNSL mechanisms and pathways are being evaluated; inhibition of Bruton's tyrosine kinase (BTK) downstream of BCR activation has demonstrated promising results in treating R/R disease. This review will summarize the evidence and potential for targeted therapeutic agents to improve treatment outcomes in PCNSL. This includes immunotherapeutic and immunomodulatory approaches and inhibitors of the key pathways driving PCNSL, such as aberrant BCR and TLR signaling.

Role of Rituximab in Treatment of Patients With Primary Central Nervous System Lymphoma (PCNSL): A Systematic Review and Meta-Analysis

Primary central nervous system lymphoma (PCNSL) is a rare form of non-Hodgkin's lymphoma involving the brain, cerebrospinal fluid, spinal cord and eyes. Rituximab has played a prominent role in the treatment of non-Hodgkin's B-cell lymphomas, including aggressive diffuse large B lymphoma. However, as a macromolecular drug, the role of rituximab in the treatment of PCNSL has been controversial. In this systematic review and meta-analysis, we evaluated the role of rituximab in the treatment of PCNSL. We searched articles in the following electronic databases including PubMed, Embase, Cochrane Library, Web of Science, and ClinicalTrials.gov until October 20, 2022.We included 11 studies (3 RCTS and 8 retrospective studies) with a total of 1182 patients. We extracted the baseline characteristics and outcomes of the studies and assessed the risk of bias, then used Review Manager 5.4 for this meta-analysis. The primary outcomes included complete response rate (CR), overall survival (OS), and progression-free survival (PFS). Odds ratios (ORS) and corresponding 95% confidence intervals (CIS) for the primary outcome were analyzed and compared. The results of our statistical analysis show that the use of rituximab was closely correlated with a higher CR(OR 1.70,95%CI 1.17-2.46, P = .005), 3-year OS (OR 2.40, 95%CI 1.53-3.77, P = .0001), 5-year OS (OR 2.75, 95%CI 1.68-4.49, P < .0001), 3-year PFS(OR 4.42, 95%CI 1.15-16.97, P < .0001), 5-year PFS(OR 1.97, 95%CI 1.39-2.78, P = .0001).These results suggest that rituximab may have a positive impact on the prognosis of patients with PCNSL, and may be helpful in the determination of treatment plan for patients with PCNSL.

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.

Development of a novel Indium-111 radiolabeled mogamulizumab targeting CCR4 for imaging adult T-cell leukemia/lymphoma in vivo

OBJECTIVE

Adult T-cell leukemia/lymphoma (ATL), caused by human T-cell lymphotropic virus type I (HTLV-1) infection, is among the most aggressive categories and has the worst prognosis among T-cell lymphomas. Mogamulizumab, an anti-CC chemokine receptor 4 (CCR 4), has been shown to be effective in the treatment of ATL; however, some ATL cases are often resistant, particularly the lymphoma-type ATL. To evaluate drug delivery in vivo and identify the distribution of CCR4-positive cells in the body, we developed a novel mogamulizumab tracer labeled with Indium-111 (¹¹¹In) via diethylenetriaminepentaacetic acid (DTPA) for single-photon emission computerized tomography (SPECT), named [¹¹¹In]In-DTPA-mogamulizumab, and evaluated its potential for visualizing CCR4 expression in vivo.

METHODS

[¹¹¹In]In-DTPA-mogamulizumab was added to HCT116/CCR4 or HCT116/empty vector (EV) cells, and their radioactivity was measured 1 h after administration. A blocking study was additionally performed by treating HCT116/CCR4 cells with excess mogamulizumab in addition to [¹¹¹In]In-DTPA-mogamulizumab. The biodistribution and SPECT imaging of [¹¹¹In]In-DTPA-mogamulizumab in HCT116/CCR4 and HCT116/EV dual-xenografted BALB/c-nu mice were evaluated for 72 h after intravenous injection.

RESULTS

[¹¹¹In]In-DTPA-mogamulizumab was acquired with a radiochemical purity > 95%. The cellular uptake level of [¹¹¹In]In-DTPA-mogamulizumab by HCT116/CCR4 cells was significantly higher than that by HCT116/EV cells (HCT116/CCR4: 0.951 ± 0.069, HCT116/EV: 0.006 ± 0.001%dose/mg protein, p < 0.01), and the uptake was significantly suppressed by co-incubation with excess mogamulizumab (0.013 ± 0.003%dose/mg protein, p < 0.01). In the in vivo study, the radioactivity of the HCT116/CCR4 tumor tissue was significantly higher than that of the HCT116/EV tumor tissue at 72 h after the administration of [¹¹¹In]In-DTPA-mogamulizumab (HCT116/CCR4: 20.5 ± 5.4, HCT116/EV: 5.7 ± 1.0%ID/g), and HCT116/CCR4 tumors were clearly and specifically visualized on SPECT imaging.

CONCLUSIONS

We have successfully developed a novel SPECT imaging tracer targeting CCR4, [¹¹¹In]In-DTPA-mogamulizumab, which showed good specificity and pharmacokinetics, indicating potential in visualizing CCR4 expression in vivo.

FDG-PET/CT in Lymphoma: Where Do We Go Now?

18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) is an essential part of the management of patients with lymphoma at staging and response evaluation. Efforts to standardize PET acquisition and reporting, including the 5-point Deauville scale, have enabled PET to become a surrogate for treatment success or failure in common lymphoma subtypes. This review summarizes the key clinical-trial evidence that supports PET-directed personalized approaches in lymphoma but also points out the potential place of innovative PET/CT metrics or new radiopharmaceuticals in the future.

Central Nervous System Lymphoma: Approach to Diagnosis and Treatment

Central nervous system lymphoma (CNSL) is a rare form of extranodal non-Hodgkin lymphoma. Central nervous system lymphoma can be primary (isolated to the central nervous space) or secondary in the setting of systemic disease. Treatment of CNSL has improved since the introduction of high-dose methotrexate and aggressive consolidation regimens. However, results after treatment are durable in only half of patients, and long-term survivors may experience late neurotoxicity, impacting quality of life. Given the rarity of this disease, few randomized prospective trials exist. This leaves many questions unanswered regarding optimal first-line and salvage treatments. Recent advances in the knowledge of pathophysiology of CNSL will hopefully help the development of future treatments. This review gives an overview of the epidemiology, pathophysiology, clinical presentation, diagnosis, and treatment of immunocompetent patients with CNSL.

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.

Molecular imaging in lymphoma beyond 18F-FDG-PET: understanding the biology and its implications for diagnostics and therapy

Mature lymphoproliferative diseases are a heterogeneous group of neoplasms arising from different stages of B-cell and T-cell development. With improved understanding of the molecular processes in lymphoma and novel treatment options, arises a growing need for the molecular characterisation of tumours. Molecular imaging with single-photon-emission CT and PET using specific radionuclide tracers can provide whole-body information to investigate cancer biology, to evaluate phenotypic heterogeneity, to identify resistance to targeted therapy, and to assess the biodistribution of drugs in patients. In this Review, we evaluate the existing literature on molecular imaging in lymphoma, other than ¹⁸F-fluordeoxyglucose molecular imaging. The aim is to examine the contribution of molecular imaging to the understanding of the biology of lymphoma and to discuss potential implications for the diagnostics and therapy of this disease. Finally, we discuss possible applications for molecular imaging of patients with lymphoma in the clinical context.

Rituximab in primary central nervous system lymphoma-A systematic review and meta-analysis

The CD-20 antibody rituximab is a standard component of treatment of non-Hodgkin B-cell lymphomas, including diffuse large B-cell lymphoma (DLBCL). Primary DLBCL of the central nervous system, also called primary central nervous system lymphoma (PCNSL), is a DLBCL confined to the central nervous system. There has been debate whether intravenous rituximab accumulates sufficiently in the central nervous system to exert an effect. In this systematic review, we assess the benefits and harms of rituximab in the treatment of immunocompetent patients with PCNSL. By searching MEDLINE, CENTRAL, and ClincialTrials.gov up to March 2019, we identified randomized controlled trials (RCTs) investigating the effect of rituximab in patients with PCNSL. We extracted study characteristics and results, assessed risk of bias, performed trial-level random-effects meta-analyses, and graded the certainty of evidence. The protocol was registered with PROSPERO (CRD42019121965). Main outcomes were overall survival (time to death), progression-free survival (time to progression or death), quality of life, grades 3 and 4 toxicity, and treatment-related mortality. We included two RCTs with a total of 343 participants. Overall survival was not statistically significantly improved (HR 0.76; 95% CI, 0.52-1.12; low certainty), with 187 fewer to 39 more deaths after 2 years in 1000 treated patients. Low certainty of evidence indicated that rituximab improved progression-free survival (HR 0.65; 95% CI, 0.45-0.95), which translated into 137 fewer progressions or deaths after 2 years in 1000 treated patients (231 to 18 fewer). None of the RCTs provided data on quality of life. We found no evidence that rituximab increased grades 3 and 4 toxicity or treatment-related mortality (RR 0.53; 95% CI, 0.20-1.37; low certainty). Overall, the available evidence suggests with low certainty that rituximab in combination with methotrexate-based chemotherapy may improve progression-free survival in immunocompetent patients with newly diagnosed PCNSL, the pooled effect estimates did not show evidence for improvement of overall survival.

Molecular imaging of bone metastases using tumor-targeted tracers

Bone metastasis is a disastrous manifestation of most malignancies, especially in breast, prostate and lung cancers. Since asymptomatic bone metastases are not uncommon, early detection, precise assessment, and localization of them are very important. Various imaging modalities have been employed in the setting of diagnosis of bone metastasis, from plain radiography and bone scintigraphy to SPECT, SPECT/CT, PET/CT, MRI. However, each modality showed its own limitation providing accurate diagnostic performance. In this regard, various tumor-targeted radiotracers have been introduced for molecular imaging of bone metastases using modern hybrid modalities. In this article we review the strength of different cancer-specific radiopharmaceuticals in the detection of bone metastases. As shown in the literature, among various tumor-targeted tracers, 68Ga DOTA-conjugated-peptides, 68Ga PSMA, 18F DOPA, 18F galacto-RGD integrin, 18F FDG, 11C/18F acetate, 11C/18F choline, 111In octreotide, 123/131I MIBG, 99mTc MIBI, and 201Tl have acceptable capabilities in detecting bone metastases depending on the cancer type. However, different study designs and gold standards among reviewed articles should be taken into consideration.

Management of primary central nervous system lymphoma

A rare tumor, primary central nervous system lymphoma can affect immunocompetent and immunocompromised patients. While sensitive to radiotherapy or chemotherapy crossing the blood-brain barrier, it often recurs. Modern treatment consists of high-dose methotrexate-based induction chemotherapy, often followed by consolidation with either radiotherapy or further chemotherapy. Neurotoxicity is however a concern with radiotherapy, especially for patients older than 60 years. The benefit of the addition of rituximab to chemotherapy is unclear. Targeted therapies and immunotherapy have been effective in some patients and are tested on a larger scale. Survival has improved in the last decade, but remains poor in older patients.

Challenges and prospects in the diagnosis and treatment of primary central nervous system lymphoma

Introduction: Primary central nervous system lymphoma (PCNSL) retains peculiar biological and clinical characteristics and a worse prognosis with respect to other comparable lymphomas. The need for high doses of chemotherapy to achieve valid drug concentrations in cerebral tissues and/or radiotherapy results in severe treatment-related toxicities, mainly neurologic, which are frequently as disabling as the disease itself.Areas covered: Several emerging combined therapies are addressed that focus on treating PCNSL. The prognosis has improved in the last years but several questions remain unanswered and the research of more effective therapies goes on. Information and data were obtained from direct authors' experience and a PubMed search of recent peer-reviewed original articles, review articles, and clinical guidelines.Expert commentary: The substantial progress observed in PCNSL has to be ascribed to a carefully combination of standard chemotherapeutic drugs. High-dose methotrexate-based polychemotherapy followed by mainteinance therapy offers one of the best chances to control the disease. Major issues that deserve many efforts by researchers are the definition of optimal consolidation treatment and a shared management of specific conditions such as elderly population and intra-ocular localization.

Primary CNS Lymphoma

Primary CNS lymphoma (PCNSL) is a rare form of extranodal non-Hodgkin lymphoma that is typically confined to the brain, eyes, and cerebrospinal fluid without evidence of systemic spread. The prognosis of patients with PCNSL has improved during the last decades with the introduction of high-dose methotrexate. However, despite recent progress, results after treatment are durable in half of patients, and therapy can be associated with late neurotoxicity. PCNSL is an uncommon tumor, and only four randomized trials and one phase III trial have been completed so far, all in the first-line setting. To our knowledge, no randomized trial has been conducted for recurrent/refractory disease, leaving many questions unanswered about optimal first-line and salvage treatments. This review will give an overview of the presentation, evaluation, and treatment of immunocompetent patients with PCNSL.

Primary central nervous system lymphoma: current state of anti-CD20 therapy and appraisal of reported response criteria

Primary central nervous system lymphoma (PCNSL) is an aggressive non-Hodgkin's lymphoma which is confined to the central nervous system and may also affect intraocular structures. Despite high initial rates of response to methotrexate-based chemotherapy, more than 50% of patients will experience relapse and about 10% have disease that is refractory to chemotherapy. Outcome in patients who fail treatment is very poor, and therefore new therapeutic approaches that may increase the rate of complete response and the proportion of durable remission are sought. Based on the pivotal role that anti-CD20 therapy now plays in the treatment outcome of aggressive systemic B-cell lymphomas, a similar approach is commonly being adapted for PCNSL despite the lack of evidence for its effectiveness. This review examines the current status and level of evidence for the use of monoclonal antibodies against the CD20 surface antigen, which is present on normal and malignant B-cells in PCNSL. The review covers both systemic and local (intracerebrospinal fluid or intravitreal) administration of CD20 monoclonal antibodies in PCNSL. In addition, it scrutinizes the response criteria commonly reported for evaluation of treatment outcome. The importance of differentiating unconfirmed complete response from partial response is outlined and the lack of consensus on response criteria for atypical imaging presentations of PCNSL is delineated.

Managing lymphoma with non-FDG radiotracers: current clinical and preclinical applications

Nuclear medicine imaging modalities such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have played a prominent role in lymphoma management. PET with [(18)F]Fluoro-2-deoxy-D-glucose (FDG) is the most commonly used tool for lymphoma imaging. However, FDG-PET has several limitations that give the false positive or false negative diagnosis of lymphoma. Therefore, development of new radiotracers with higher sensitivity, specificity, and different uptake mechanism is in great demand in the management of lymphoma. This paper reviews non-FDG radiopharmaceuticals that have been applied for PET and SPECT imaging in patients with different types of lymphoma, with attention to diagnosis, staging, therapy response assessment, and surveillance for disease relapse. In addition, we introduce three radiolabeled anti-CD20 antibodies for radioimmunotherapy, which is another important arm for lymphoma treatment and management. Finally, the relatively promising radiotracers that are currently under preclinical development are also discussed in this paper.

Pathogenesis and management of primary CNS lymphoma

Primary CNS lymphoma (PCNSL), a rare variant of extranodal non-Hodgkin's lymphoma, may cause various neurological symptoms and signs. The best therapeutic strategy is still a matter of debate. High-dose methotrexate (HD-MTX) is the most active compound and should be used as the backbone for any chemotherapy applied. Several other chemotherapeutic drugs have been assessed in combination with HD-MTX, but no standard has yet been defined. Whole-brain radiotherapy is active against PCNSL, but typically does not confer long-lasting remission and is associated with significant neurotoxicity in many patients. The recently published G-PCNSL-SG1 trial has shown that consolidating whole-brain radiotherapy after HD-MTX-based chemotherapy does not prolong overall survival and may therefore be deferred. Combined systemic and intraventricular polychemotherapy, or high-dose chemotherapy followed by stem cell transplantation may offer cures to younger patients. Improving treatment regimens without adding significant (neuro-)toxicity should be the focus of ongoing and future studies.

Cancer radioimmunotherapy

Targeting of radionuclides with antibodies, or radioimmunotherapy, has been an active field of research spanning nearly 50 years, evolving with advancing technologies in molecular biology and chemistry, and with many important preclinical and clinical studies illustrating the benefits, but also the challenges, which all forms of targeted therapies face. There are currently two radiolabeled antibodies approved for the treatment of non-Hodgkin lymphoma, but radioimmunotherapy of solid tumors remains a challenge. Novel antibody constructs, focusing on treatment of localized and minimal disease, and pretargeting are all promising new approaches that are currently under investigation.

How I treat primary CNS lymphoma

Primary CNS lymphoma (PCNSL) is a rare malignancy with peculiar clinical and biologic features, aggressive course, and unsatisfactory outcome. It represents a challenge for multidisciplinary clinicians and scientists as therapeutic progress is inhibited by several issues. Molecular and biologic knowledge is incomplete, limiting the identification of new therapeutic targets, and the particular microenvironment of this malignancy, and sanctuary sites where tumor cells grow undisturbed, strongly affects treatment efficacy. Moreover, active treatments are known to be associated with disabling neurotoxicity, posing the dilemma of whether to intensify therapy to improve the cure rate or to de-escalate treatment to avoid sequels. The execution of prospective trials is also difficult because of the rarity of the tumor and the impaired general condition and poor performance status of patients. Thus, level of evidence is low, with consequent uncertainties in therapeutic decisions and lack of consensus on primary endpoints for future trials. Despite this unfavorable background, laboratory and clinical researchers are coordinating efforts to develop new ideas, resulting in the recent publication of studies on PCNSL's biology and molecular mechanisms and of the first international randomized trials. Herein, these important contributions are analyzed to provide recommendations for everyday practice and the rationale for future trials.

Primary CNS lymphoma

Primary CNS Lymphoma (PCNSL) accounts for 3% of all primary brain tumors with a median age at onset of about 62 years. In the vast majority of cases, PCNSL presents as unifocal or multifocal enhancing lesions on MRI, frequently adjacent to the ventricles. Stereotactic biopsy is the diagnostic procedure of choice revealing high-grade malignant non-Hodgkin's B-cell lymphoma in more than 90% of cases. Therapy is not evidence based. When eligible, patients should be included in clinical trials. In patients younger than 60 years cure is the aim. Polychemotherapy based on high-dose methotrexate (MTX) or alternatively high-dose chemotherapy with autologous stem cell rescue should be offered to patients eligible for this regimens. For patients over 60 years of age no curative regimen with acceptable toxicity has yet been established. An MTX-based chemotherapy, for example, in combination with temozolomide, is recommended. The role of radiotherapy as part of the initial treatment is not established; however, the combination of radiotherapy with MTX-based chemotherapy potentially leads to severe long-term neurotoxic sequelae. Therefore, radiotherapy as part of the initial therapy is not recommended by the author outside clinical trials. At relapse or in cases of refractory disease, patients will frequently benefit of salvage therapy, which depends on the initial treatment.

Cancer immunotherapy

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

Pharmacotherapy for primary CNS lymphoma: progress beyond methotrexate?

Studies conducted in the 1990s have established that high-dose methotrexate-based chemotherapy added to whole-brain radiotherapy improves survival in primary CNS lymphoma (PCNSL). However, radiotherapy-related delayed neurotoxicity has emerged as a serious complication of chemo-radiotherapy, particularly in the elderly. Unfortunately, omitting radiotherapy results in decreased progression-free survival, and therefore establishing more effective chemotherapy regimens is necessary in order to improve the number of long-term remissions. Recent studies have suggested that a combination of drugs is superior to single-agent methotrexate, but the optimal chemotherapy combination and the role of alternative consolidation treatments such as reduced-dose radiotherapy and high-dose chemotherapy with stem cell rescue remain to be defined. In this article, we review the multiple chemotherapy options reported in newly diagnosed and in progressive/refractory PCNSL, including recently reported and ongoing clinical trials, as well as future perspectives.

Primary central nervous system lymphoma

PURPOSE OF REVIEW

This review will summarize recent advances in the understanding and treatment of primary central nervous system lymphoma (PCNSL).

RECENT FINDINGS

The molecular and genetic characteristics that distinguish PCNSL are beginning to be elucidated. New tools such as flow cytometry and PET are improving the diagnosis and management of PCNSL. Although the current standard of care is high-dose methotrexate-based chemotherapy alone or in combination with whole brain radiotherapy, multiple questions remain regarding the optimal treatment of PCNSL, in general, and unusual variants of PCNSL.

SUMMARY

Although recent advances have improved our understanding of PCNSL, the need for additional collaborative research is critical.

Management of immunocompetent patients with primary central nervous system lymphoma

Primary central nervous system (CNS) lymphoma (PCNSL) is a non-Hodgkin lymphoma that arises within and is confined to the CNS. Recent data have suggested an increasing incidence in immunocompetent individuals, with a peak of incidence between 60 and 70 years of age. Patients with PCNSL present mostly with symptoms of increased intracranial pressure. The clinical management of these patients remains controversial, and the optimal treatment for patients with PCNSL has not yet been defined. Surgery, even if macroscopically radical, does not improve survival because of the multifocal and infiltrative nature of PCNSL; furthermore, the deep location of most of these tumors makes patients susceptible to serious and irreversible neurologic sequelae. Corticosteroids have a specific role in the treatment of patients with PCNSL, whose disease is sensitive to them as a chemotherapeutic agent. PCNSL is an extremely radiation-sensitive neoplasm; whole-brain radiation therapy plus corticosteroids was the first modality of treatment for patients with this neoplasm until 10 years ago, with a low cure rate and a high local recurrence rate. PCNSL is also a chemosensitive neoplasm; while the optimal choice, sequence, and combination of appropriate agents for efficacious treatment of patients with PCNSL has yet to be determined. An essential component of therapy must include an adequate drug delivery behind a normal blood-brain barrier. Methotrexate is the agent with the most proven activity in PCNSL. Combined-modality therapy has improved survival, but relapse is still common, and late neurologic toxicity is a significant complication, especially in older patients, who represent the majority of immunocompetent patients with PCNSL.

Primary central nervous system lymphoma: an update

PURPOSE OF REVIEW

The purpose of the present review is to present an overview of the recent findings in diagnostic procedures, treatment outcomes and biological advances in primary central nervous system lymphoma (PCNSL).

RECENT FINDINGS

Recent imaging techniques are helpful in the diagnosis of atypical presentations of PCNSL and are likely to represent useful tools for patient follow-up. Knowledge of the biology of PCNSL is still fragmentary, but an increasing amount of data support the biological specificity of this disease with the identification of specific molecular alterations in PCNSL and specific interactions of lymphoma cells with the CNS microenvironment. The origin of the malignant cell is still unknown. Improvement of the therapeutic results along with numerous phase II studies clearly highlight a few important issues that need to be unequivocally answered and stress the need for the development of multicentric comparative studies. Attempts to decrease treatment-related toxicity on the CNS without impacting the disease control are ongoing.

SUMMARY

The standard of care for PCNSL has definitively switched toward a curative objective. Considerable cooperative efforts are being made and will hopefully result in both a better understanding of the disease and significant therapeutic outcomes.

Therapeutic challenges in primary CNS lymphoma

Optimum treatment for patients with primary CNS lymphoma remains challenging because there have not been any large randomised clinical trials of this rare tumour. Drugs used in treating systemic non-Hodgkin lymphoma have mostly proven ineffective because of difficulties crossing the blood-brain barrier. The recognition of the efficacy of high-dose methotrexate was a substantial therapeutic breakthrough and further advances, such as the development of polychemotherapy regimens, have built on this. Whole-brain radiotherapy can consolidate response to chemotherapy, but the associated toxic effects of chemoradiation can be unacceptable. Other effective approaches include disruption of the blood-brain barrier and the use of high-dose chemotherapy. Recently, there have been attempts to optimise multi-drug chemotherapy regimens by focusing on improving survival and reducing toxic effects. A promising area of research is the incorporation of novel targeted drugs into standard treatment frameworks. In the future, greater cooperation between research groups should hopefully lead to further therapeutic advances.

First report on a prospective trial with yttrium-90-labeled ibritumomab tiuxetan (Zevalin) in primary CNS lymphoma

Most patients with primary CNS lymphoma (PCNSL) relapse after primary therapy. Standard salvage treatment has not yet been established in PCNSL. Anti-CD20 immunotherapy has expanded treatment options in systemic B-cell lymphoma; however, its use is limited by reconstitution of the blood-brain barrier after tumor shrinkage. The aim of this phase II trial was to evaluate the therapeutic efficacy, toxicity, and biodistribution of yttrium-90 ((90)Y) ibritumomab tiuxetan in PCNSL. Ten patients with relapsed PCNSL were included in a phase II trial and treated with the (90)Y-labeled anti-CD20 antibody ibritumomab tiuxetan. Nine patients actually received the planned radioimmunotherapy. In six patients, biodistribution of the antibody was measured by indium-111 ((111)In) ibritumomab tiuxetan whole-body scans and single-photon-emission CT (SPECT) of the brain. All patients were evaluated for toxicity and response at least 4 weeks after therapy. Four patients responded: one patient had a complete response lasting 30+ months, and three patients had short-lived responses of </=4 weeks. Five patients progressed, and one patient did not receive treatment due to an infection prior to (90)Y-antibody administration. Target accumulation of the antibody was demonstrated in four of the six patients examined by SPECT imaging with (111)In ibritumomab tiuxetan. All patients experienced grade 3/4 hematotoxicity but no acute neurotoxicity. Penetration of a therapeutic antibody into PCNSL and significant clinical activity was shown. Because of limited response duration and considerable hematotoxicity, future investigations should focus on a multimodal approach with additional chemotherapy and preferably autologous stem cell support.