Liquid biopsy for improving diagnosis and monitoring of CNS lymphomas: a RANO review

BACKGROUND

The utility of liquid biopsies is well documented in several extracranial and intracranial (brain/leptomeningeal metastases, gliomas) tumors.

METHODS

The RANO (Response Assessment in Neuro-Oncology) group has set up a multidisciplinary Task Force to critically review the role of blood and CSF-liquid biopsy in central nervous system lymphomas, with a main focus on primary central nervous system lymphomas (PCNSL).

RESULTS

Several clinical applications are suggested: diagnosis of PCNSL in critical settings (elderly or frail patients, deep locations, steroids responsiveness), definition of minimal residual disease, early indication of tumor response or relapse following treatments and prediction of outcome.

CONCLUSIONS

Thus far, no clinically validated circulating biomarkers for managing both primary and secondary CNS lymphomas exist. There is need of standardization of biofluid collection, choice of analytes and type of technique to perform the molecular analysis. The various assays should be evaluated through well organized central testing within clinical trials.

EBV-positive PCNSL in older patients: incidence, characteristics, tumor pathology, and outcomes across a large multicenter cohort

The objective of this multicenter retrospective study was to examine the incidence, patient characteristics, pathology, and outcomes associated with Epstein-Barr virus (EBV)-related CNS lymphoma (CNSL) in older patients. Among 309 CNSL patients aged ≥60, 11.7% had EBV + tumors of which 72.2% were solid organ transplant (SOT)-related post-transplant lymphoproliferative disorders (PTLD). Younger age, SOT or autoimmune disease, and immunosuppressive treatment correlated highly with EBV-positivity. EBV + tumors were associated with absent C-MYC and BCL6 expression. EBV + PTLD was more likely to be associated with the absence of CD5 expression. EBV + non-PTLD had better median OS (not reached) compared to EBV + PTLD (10.8 months) and EBV-negative patients (43 months). Multivariable Cox regression analysis showed that age, performance status, and PTLD were negative predictors of OS. EBV status and immunosuppressive treatment were not correlated with OS. Our findings merit further investigation of EBV + PCNSL tumors and EBV-directed therapies.

Stereotactic Radiosurgery for Primary Central Nervous System Lymphoma

Background Primary central nervous system lymphoma (PCNSL) is rare, with a treatment backbone that typically includes high-dose methotrexate-based chemotherapy, with radiation often reserved for persistent or progressive disease. In this study, we report the outcomes of stereotactic radiosurgery (SRS) in patients with PCNSL to potentially defer whole brain radiotherapy (WBRT) or as salvage after WBRT. Methodology We performed a single-institution, retrospective review of 20 patients with PCNSL who received single-fraction or fractionated SRS to 32 lesions between September 1992 and July 2019. Results The median age at SRS was 67 years (interquartile range (IQR) = 56-74 years). The median Karnofsky Performance Status (KPS) at SRS was 80 (IQR = 50-80). In total, 18 (90%) patients received methotrexate-based chemotherapy prior to SRS, with a median of eight cycles (IQR = 5-10). A total of 10 patients received SRS for recurrent disease after chemotherapy and/or WBRT, nine patients received SRS for the persistent disease after chemotherapy alone, and one patient received up-front SRS. Overall, five patients received SRS following WBRT. The median SRS dose was 16 Gy (IQR = 14-22.5 Gy) in one fraction (IQR = 1-5 fractions). Eight patients (40%) were treated with consolidative pomalidomide or lenalidomide following SRS. The local control rate was 100% (32/32 lesions at a median follow-up of 15 months). In total, 13 of 16 (81%) patients with available follow-up experienced distant brain recurrence. The median time to distant failure following SRS was 10 months (IQR = 1-16 months). Three patients received salvage SRS, and three patients received salvage WBRT. The median overall survival from diagnosis was 39 months (95% confidence interval = 24-54 months). KPS at the time of SRS was significantly correlated with time to progression (p = 0.002). The use of lenalidomide or pomalidomide after SRS was associated with improved overall survival after SRS (three vs. 14 months, p = 0.035). Consolidative etoposide and cytarabine after initial methotrexate-based chemotherapy was also associated with improved survival following SRS (eight vs. 47 months, p = 0.028). Conclusions SRS offers effective local tumor control for patients with PCNSL; however, the majority of patients experience distant progression. SRS may have a role in the salvage setting for patients with recurrence after WBRT, or allow deferral of WBRT in select patients, although systemic therapy appears to strongly influence outcomes in this cohort.

Primary CNS lymphoma: update on molecular pathogenesis and therapy

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive form of extra-nodal non-Hodgkin lymphoma that as a brain tumor poses a unique set of challenges in diagnosis and management. With the advent of next-generation sequencing, we review updates in the understanding of its molecular and genomic pathogenesis. We also highlight key issues in management, with a focus on emerging technologies and new biological therapies including monoclonal antibodies, IMiDs, BTK inhibitors, PD-1 inhibitors, and CAR-T therapy. Integration of these approaches will likely enhance induction and consolidation strategies to suppress NF-κB activation and the anti-tumor immune response, while minimizing the often noxious effects of genotoxic approaches.

Primary CNS Lymphoma: Progress With Dose-Intensive Consolidation

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.

Acquired factor VII inhibitor associated with primary central nervous system Lymphoma: A case report

Paraneoplastic coagulopathies are uncommon in patients with lymphoma. We report the first case of an acquired coagulopathy in a patient with isolated primary central nervous system lymphoma (PCNSL) demonstrating large‐cell histology. In our patient, a paraneoplastic factor VII inhibitor significantly delayed a diagnostic lumbar puncture despite fresh frozen plasma and inactivated prothrombin complex concentrate. While her coagulopathy was effectively overcome with recombinant activated factor VIIa and subsequently with lymphoma‐directed therapy, her delayed diagnosis likely contributed to a poor outcome. Our case highlights the importance of rapidly identifying and correcting paraneoplastic coagulopathies when PCNSL is suspected.

Primary central nervous system lymphoma in older adults and the rationale for maintenance strategies: a narrative review

Objective:

To provide a summary and analysis of the evidence for various agents applied as maintenance therapy and highlight ongoing trials or trials in development that evaluate the efficacy of maintenance therapy strategies in older patients with primary central nervous system lymphoma (PCNSL).

Background:

PCNSL are rare neoplasms that can have an aggressive course with short-lived remissions when compared to systemic diffuse large B-cell lymphoma (DLBCL). There is currently a paucity of evidence on treatment in older adults with PCNSL, who may be unfit to tolerate effective therapies for PCNSL. Those who can tolerate these therapies and survive PCNSL are at increased risk from developing treatment-related toxicity, functional decline, and debilitating neurotoxicity. While there is no clearly defined role for maintenance therapy after treatment of systemic DLBCL, it should be considered in PCNSL because central nervous system (CNS) recurrence often has a devastating and irreversible impact on neurologic function. Therefore, at least theoretically, use of effective maintenance therapy in older adults with PCNSL, either in lieu of consolidation or after consolidation therapy, may be better tolerated and help delay tumor progression, resulting in an improved overall global neurologic function and quality of life.

Methods:

We systematically searched MEDLINE (via PubMed) for all studies of drug treatments for maintenance therapy in PCNSL and also relied on expert opinion. We provide a summary and analysis of the evidence for various maintenance therapy agents, including methotrexate, rituximab, lenalidomide, temozolomide, ibrutinib, and procarbazine. We also highlight ongoing trials or trials in development that evaluate the efficacy of maintenance therapy in PCNSL.

Conclusions:

Prospective clinical studies focusing on PCNSL patients who are not candidates for intensive post-induction therapy are scarce. To date, there are no studies that clarify whether maintenance therapy can be used in lieu of consolidation therapy with autologous stem cell transplant or radiation. Prospective studies may provide critical data regarding the identification of optimal agents, whether consolidation therapy could be replaced by maintenance therapy, and the overall role of maintenance therapy as a means to potentially improve survival and preserve quality of life and function in a vulnerable, older patient population.

Consensus recommendations for MRI and PET imaging of primary central nervous system lymphoma: guideline statement from the International Primary CNS Lymphoma Collaborative Group (IPCG)

Advanced molecular and pathophysiologic characterization of primary central nervous system lymphoma (PCNSL) has revealed insights into promising targeted therapeutic approaches. Medical imaging plays a fundamental role in PCNSL diagnosis, staging, and response assessment. Institutional imaging variation and inconsistent clinical trial reporting diminishes the reliability and reproducibility of clinical response assessment. In this context, we aimed to: (1) critically review the use of advanced positron emission tomography (PET) and magnetic resonance imaging (MRI) in the setting of PCNSL; (2) provide results from an international survey of clinical sites describing the current practices for routine and advanced imaging, and (3) provide biologically based recommendations from the International PCNSL Collaborative Group (IPCG) on adaptation of standardized imaging practices. The IPCG provides PET and MRI consensus recommendations built upon previous recommendations for standardized brain tumor imaging protocols (BTIP) in primary and metastatic disease. A biologically integrated approach is provided to addresses the unique challenges associated with the imaging assessment of PCNSL. Detailed imaging parameters facilitate the adoption of these recommendations by researchers and clinicians. To enhance clinical feasibility, we have developed both “ideal” and “minimum standard” protocols at 3T and 1.5T MR systems that will facilitate widespread adoption.

Myeloablative versus non-myeloablative consolidative chemotherapy for newly diagnosed primary central nervous system lymphoma: Results of CALGB 51101 (Alliance)

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Background: Optimal consolidative therapy for primary central nervous system lymphoma (PCNSL) is not defined. Avoidance of whole brain radiation may reduce risk of neurotoxicity. Non-radiation consolidative options include myeloablative chemotherapy with autologous stem cell transplantation (HDT/ASCT) or non-myeloablative chemotherapy. Methods: This is a randomized phase 2, National Clinical Trials Network study of induction methotrexate (MTX) (8 g/m2 days 1, 15), temozolomide (TMZ) (150-200 mg/m2 D7-11), and rituximab (RTX) (C1 D3, 10, 17, 24 and C2 D3, 10 ) in four 28-day cycles followed by one cycle of cytarabine (ARA-C) (2 g/m2 BID, D1, 2) (MTRA). After induction, patients (pts) received consolidation with thiotepa (5 mg/kg BID, D -5, -4) plus carmustine (400 mg/m2, day -6) and ASCT (Arm A) or one cycle of ARA-C (2 g/m2 BID, D1-4) plus infusional etoposide (40 mg/kg over 96h) (Arm B). Pts were stratified on age and performance status and randomized 1:1 before induction. The primary endpoint was progression-free survival (PFS) from randomization. With 110 pts, there was 84% power to detect an improvement in PFS using a log-rank test (1-sided α= 10%), assuming a median PFS of 3 months for pts who progress during induction, and a median PFS of 2 years (yrs) for Arm B and 4.5 yrs for Arm A consolidation. This report includes the results for the primary endpoint analysis. Results: 113 pts (median age 61 yrs, range 33-75) were randomized (Arm A: 57, Arm B: 56) across 27 centers. 108 eligible pts who received induction therapy were included in the primary endpoint analysis (Arm A: 54, Arm B: 54). 72/108 pts started consolidation and 70/72 completed consolidation per protocol (Arm A: 36, Arm B: 34). With a median follow-up of 3.8 years, median PFS from randomization was 6 yrs (95% CI 3.9-not reached) in Arm A vs 2.4 yrs (95% CI 0.6-not reached) in Arm B (p = 0.02). However, more pts randomized to Arm B went off treatment before consolidation due to progression or death (28% vs 11%, p = 0.05). PFS landmarked at start of consolidation demonstrated a trend for improved PFS favoring Arm A (HR 0.58, 95% CI 0.25-1.36; p = 0.21). Median OS was not reached in either arm, and 3-yr estimates were 83% (95% CI 69-91; Arm A) vs 72% (95% CI 57-82; Arm B). Toxicities were similar between arms with no treatment-related mortality during consolidation. Conclusions: MTRA induction followed by myeloablative consolidation (Arm A) had improved PFS vs MTRA induction followed by non-myeloablative consolidation (Arm B), though more progressions or deaths leading to treatment discontinuation prior to consolidation in Arm B were noted. Both consolidation regimens were well-tolerated with encouraging PFS and OS in newly-diagnosed PCNSL. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org . Clinical trial information: NCT01511562.

Blood Coagulation Factor Fibrinogen in Tumor Pathogenesis of Central Nervous System B-Cell Lymphoma

Central nervous system (CNS) lymphoma is an extranodal non-Hodgkin B-cell lymphoma characterized by malignant lymph tissue arising in the brain or spinal cord, associated with inflammation and blood-brain barrier (BBB) disruption. Although BBB disruption is known to occur in patients with CNS lymphoma, a direct link between these two has not been shown. Herein, abundant deposition of the blood coagulation protein fibrinogen around B-cell lymphoma was detected in CNS lymphoma patients and in the CNS parenchyma in an orthotopic mouse model. Functional enrichment analysis of unbiased cerebrospinal fluid proteomics of CNS B-cell lymphoma patients showed that coagulation protein networks were highly connected with tumor-associated biological signaling pathways. In vivo two-photon imaging demonstrated that lymphoma growth was associated with BBB disruption, and in vitro experiments identified a role for fibrinogen in promoting lymphoma cell adhesion. Overall, these results identify perivascular lymphoma clustering at sites of fibrinogen deposition, and suggest that fibrinogen may be a target for pharmacologic intervention in metastatic B-cell lymphoma associated with BBB disruption.

Tumor Metabolism and Neurocognition in CNS Lymphoma

BACKGROUND

The mechanistic basis for neurocognitive deficits in CNS lymphoma and other brain tumors is incompletely understood. We tested the hypothesis that tumor metabolism impairs neurotransmitter pathways and neurocognitive function.

METHODS

We performed serial cerebrospinal fluid (CSF) metabolomic analyses using liquid chromatography-electrospray tandem mass spectrometry to evaluate changes in the tumor microenvironment in 14 patients with recurrent CNS lymphoma, focusing on 18 metabolites involved in neurotransmission and bioenergetics. These were paired with serial mini-mental state examinations (MMSE) and MRI studies for tumor volumetric analyses. Patients were analyzed in the setting of the phase I trial of lenalidomide/rituximab. Associations were assessed by Pearson and Spearman correlation coefficient. Generalized estimating equation (gee) models were also established, adjusting for within-subject repeated measures.

RESULTS

Of 18 metabolites, elevated CSF lactate correlated most strongly with lower MMSE score (p<8E-8, rho=-0.67). High lactate was associated with lower GABA, higher glutamate/GABA ratio and dopamine. Conversely, high succinate correlated with higher MMSE score. Serial analysis demonstrated a reproducible, time-dependent, reciprocal correlation between changes in lactate and GABA concentrations. While high lactate and low GABA correlated with tumor contrast enhancing volume, they correlated more significantly with lower MMSE scores than tumor volumes.

CONCLUSIONS

We provide evidence that lactate production and Warburg metabolism may impact neurotransmitter dysregulation and neurocognition in CNS lymphomas. We identify novel metabolomic biomarkers that may be applied in future studies of neurocognition in CNS lymphomas. Elucidation of mechanistic interactions between lymphoma metabolism, neurotransmitter imbalance and neurocognition may promote interventions that preserve cognitive function.

On point in primary CNS lymphoma

Primary CNS lymphoma (PCNSL) is an aggressive brain tumor that represents a significant challenge both to elucidate its biological pathogenesis as well as to develop definitive precision medicines with minimal collateral toxicity. We highlight the key issues in diagnosis and treatment and focus on emerging technologies, current options among consolidation strategies, and biological agents. We anticipate that further development of molecular diagnostics and molecular imaging approaches that elucidate minimal residual disease in brain parenchyma, leptomeninges, intraocular compartments and even bone marrow will greatly impact the delivery and timing of cytotoxic and biological therapies. Implementation of these approaches is likely essential to clarify ongoing discrepancies in the interpretation of clinical trial results that currently are based on relatively unrefined definitions of response. While the results of early phase investigations involving ibrutinib and the IMiD agents, lenalidomide, pomalidomide, as well as avadomide, strongly support the hypothesis that the B-cell receptor (BCR) pathway, involving MYD88 and CD79B and NF-kB activation, is critical to the pathogenesis of PCNSL, much work is needed to elucidate mechanisms of resistance. Similarly, development of strategies to overcome immunosuppressive mechanisms that are upregulated in the tumor microenvironment is a high priority. Finally, ongoing evidence supports the hypothesis that the blood-brain barrier represents a significant impediment to efficient brain tumor penetration of novel therapeutic agents and innovative strategies of drug delivery remain essential to further improve outcomes.

Myeloablative versus non-myeloablative consolidative chemotherapy for newly diagnosed primary central nervous system lymphoma: Results of induction therapy in Alliance 51101

8042

Background: Optimal consolidative therapy for primary central nervous system lymphoma (PCNSL) is not defined. Avoidance of whole brain radiation may reduce risk of neurotoxicity. Non-radiation consolidative options include myeloablative chemotherapy followed by autologous stem cell transplantation (HDT/ASCT) or non-myeloablative chemotherapy. Methods: This is a randomized phase 2, National Clinical Trials Network study of induction methotrexate (MTX) (8 g/m2days 1, 15), temozolomide (TMZ) (150-200 mg/m2 D7-11), and rituximab (RTX) (C1 D3, 10, 17, 24 and C2 D3, 10) in four 28-day cycles followed by one cycle of cytarabine (ARA-C) (2 g/m2 BID, D1, 2) (MTRA). Following induction, patients (pts) received consolidation with thiotepa (5 mg/kg BID, D -5, -4) plus carmustine (400 mg/m2, day -6) and ASCT (Arm A) or one cycle of ARA-C (2 g/m2 BID, D1-4) plus infusional etoposide (40 mg/kg over 96h) (Arm B). The primary endpoint was median progression-free survival (PFS), designed to compare consolidation regimens. This report describes the results of the 5 cycles of induction therapy. Results: 113 pts (median age 61 years, range 33-75) were randomized (Arm A: 57, Arm B: 56) across 27 centers. 108 eligible pts who received induction therapy were evaluated. 36 pts (33.3%) did not proceed to consolidation, mainly due to disease progression (17), pt withdrawal (8), or adverse events including death (6). Grade 3 or 4 febrile neutropenia occurred in 12 pts (11.1%) during induction. Dose modifications of MTX were required in 75% of pts and 63.3% of cycles, mainly due to renal adjustments. Dose delays of MTX were required in 52.8% of pts and 22.2% of cycles. Overall response rate (CR, CRu, PR) at the end of induction was 65.7% (95% CI, 56%, 74.6%). Conclusions: While MTRA is feasible and active a significant proportion of pts did not receive consolidation, supporting the need to develop more effective induction strategies. Clinical trial information: NCT01511562 .

Comprehensive approach to diagnosis and treatment of newly diagnosed primary CNS lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare form of non-Hodgkin lymphoma that affects the brain parenchyma, spinal cord, eyes, and cerebrospinal fluid without evidence of systemic, non-CNS involvement. PCNSL is uncommon and only a few randomized trials have been completed in the first-line setting. Over the past decades, the prognosis of PCNSL has improved, mainly due to the introduction and widespread use of high-dose methotrexate, which is now the backbone of all first-line treatment polychemotherapy regimens. Despite this progress, durable remission is recorded in only 50% of patients, and therapy can be associated with significant late neurotoxicity. Here, we overview the epidemiology, clinical presentation, staging evaluation, prognosis, and current up-to-date treatment of immunocompetent PCNSL patients.

An audit of retinal lymphoma treatment at the University of California San Francisco

BACKGROUND/OBJECTIVES

To evaluate retinal lymphoma treatment at the University of California San Francisco.

SUBJECTS/METHODS

Prospective observational audit. Patients were treated systemically, usually with: methotrexate, temozolomide, and rituximab induction; etoposide consolidation; and maintenance with lenalidomide or another immunomodulatory agent. Persistent disease was treated initially by ocular radiotherapy or intravitreal melphalan and latterly by vitrectomy.

RESULTS

The cohort comprised eight females and two males. The median age was 58 years (range, 38-73). Ocular manifestations were initially unilateral in four patients. Vitreous and subretinal infiltrates were initially present in 16 and 12 eyes, respectively, with three eyes having vision of 20/200 or worse. Four patients had a history of central nervous system (CNS) lymphoma. The median ophthalmic follow-up was 37 months (range, 8-56). Diagnostic and therapeutic vitrectomy were performed in 10 and 2 eyes, respectively. All patients had systemic chemotherapy and eight received maintenance immunotherapy. Four patients underwent ocular radiotherapy, bilaterally in two. One patient received bilateral intravitreal melphalan injections. Two eyes of four patients developed lymphoma during the study and two patients developed CNS disease. At study close, subretinal deposits were subtle in nine eyes and more prominent in two, whereas vitreous infiltrates were minimal in nine eyes, mild in one and moderate in one. The latest visual acuity was significantly worse than at presentation in two eyes and better in two. All patients were alive with no active CNS disease.

CONCLUSIONS

Subretinal lymphomatous infiltrates respond to systemic chemotherapy with immunomodulatory maintenance, but dense vitreous infiltrates require therapeutic vitrectomy.

Evolving Treatments for Primary Central Nervous System Lymphoma

Primary central nervous system (CNS) lymphoma (PCNSL) is an aggressive form of non-Hodgkin lymphoma that remains confined to the CNS neuroaxis during its natural history of disease and is therefore considered stage IE disease. PCNSL is diffuse large B-cell lymphoma (DLBCL) morphology in more than 95% of patients and is designated primary diffuse large B-cell lymphoma of the CNS on the basis of the 2017 World Health Organization classification of hematopoietic and lymphoid tumors. Rapidly evolving therapeutic paradigms have been linked to evidence of progress in PCNSL, a disease long considered to be incurable. Increasing evidence supports the need for efficient diagnosis, staging, and initiation of therapy, ideally at centers with experience with this type of brain cancer. High-dose methotrexate (MTX) remains a cornerstone of induction regimens, and most data support the use of rituximab. However, clinical research challenges must address key questions, including the development of ever more effective and less toxic induction regimens and the selection of the most appropriate and effective consolidation approaches, as well as the fact that, increasingly, PCNSL affects older patients who do not tolerate strong genotoxic irradiation or high-dose chemotherapy (HDC)-based strategies. Maintenance therapy, immunotherapy, and the implementation of targeted agents on the basis of the molecular and biologic properties of the disease create opportunities for precision medicine and the potential for long-term disease-free survival and cure, with minimal treatment-related neurotoxicity, for a greater fraction of patients.

Insights from a Case of Vitreoretinal Lymphoma

Purpose/Background

The aim of this study was to report a patient with vitreoretinal lymphoma with clinical features providing hypothesis-generating insights into the pathophysiology of this disease.

Methods

Clinical history and imaging studies (i.e., fundus photography, optical coherence tomography, fundus autofluorescence, and fluorescein angiography) were documented.

Results

A 71-year-old woman presented with a 2-month history of blurred vision in the right eye and bilateral vitreous infiltrates unresponsive to topical and systemic steroids. Vitreous biopsy of the left eye was diagnostic for lymphoma. Bulky subretinal deposits in the right eye responded to systemic therapy. The left fundus showed diffuse hypoautofluorescence and punctate, hyperfluorescent sub-retinal pigment epithelial tumor deposits, which resolved leaving hypoautofluorescent atrophic retinal pigment epithelium (RPE) scars, except inferotemporally, where retinal vasculopathy had occurred.

Conclusions

The clinical features suggest that occlusion of the inferotemporal retinal arteriole prevented sub-RPE lymphomatous deposits and subsequent RPE atrophy in this area of vascular nonperfusion. This suggests that "primary" vitreoretinal lymphoma is secondary to hematogenous spread from systemic loci. This finding, together with the ocular tumor control achieved entirely by systemic therapy, indicates scope for studies investigating systemic treatment protocols, especially those including immune-modulatory agents.

Abstract 4975: Tumor metabolism and cognitive dysfunction in CNS lymphoma

Background: The etiologic basis for neurocognitive and neuropsychological deficits in cancer patients and cancer survivors is poorly understood. Because of ongoing improvements in therapy and advances in survival, the problem of cancer-associated cognitive dysfunction is increasingly significant. While there is agreement that T2-weighted imaging abnormalities on MRI correlate with neurocognitive deficits, there has been limited insight into the neurochemical abnormalities associated with cognitive dysfunction in brain tumor patients. We are testing the hypothesis that tumor metabolism directly impairs neurotransmitter pathways and cognitive function, independent of anatomic extent of the cancer.

Methods: Our approach has been to focus on a type of brain tumor, CNS lymphoma, in which we are able to simultaneously monitor cognitive function, as assayed by repeat Mini-Mental Status Examinations (MMSE), tumor volume, as assessed by MRI, and dynamic changes in the tumor metabolic microenvironment, as characterized by quantitative measurement of tumor-associated metabolites in correlation with neurotransmitters that we hypothesize to be linked to normal cognitive function. Our initial study was to evaluate 14 subjects with CNS lymphoma that were treated on a phase I trial of the immunomodulatory agent lenalidomide. Volumetric analysis of CNS lymphomas was performed using Smartbrush Software (Brainlab) on pre-and post-therapy MRI's conducted at baseline and at monthly restaging. Metabolomic analysis of cerebrospinal fluid (CSF), using GC/MS, was conducted at baseline and at timepoints within 1 week of corresponding MRI. MMSE tests were conducted in all subjects at baseline and at corresponding monthly restaging examinations.

Results: Of 20 CSF metabolites analyzed, including 12 neurotransmitters, elevated CSF lactate correlated most strongly with impaired neurocognitive function as measured by MMSE score. (P=2.5e-6; rho= -0.66). Patients with high lactate had lower relative CSF concentration of the inhibitory neurotransmitter GABA, and higher concentrations of the excitotoxic glutamate. Notably, we determined that CSF lactate concentration more significantly correlated with lower MMSE score than size of the brain tumor, as quantified by volumetric analysis of tumor T2 hyperintensity and lesional contrast-enhancing volume.

Conclusions: To our knowledge, this is the first data linking cancer metabolism, neurotransmitter dysregulation, and neurocognitive deficits in a brain tumor patient population. We anticipate that elucidation of the mechanistic basis between tumor lactate metabolism, neurotransmitter imbalance, and neurocognitive deficits will provide potential opportunities for pharmacologic intervention to preserve neurologic function and potentially minimize cognitive and neuropsychological deficits in cancer patients.

Citation Format: Lakshmi Subbaraj, Huimin Geng, Jigyasa Sharma, Marisa LaFontaine, James L. Rubenstein. Tumor metabolism and cognitive dysfunction in CNS lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4975.

Biology of CNS lymphoma and the potential of novel agents

Primary and secondary CNS lymphomas are aggressive brain tumors that pose an immense challenge to define in terms of molecular pathogenesis, as well as to effectively treat. During the past 10 years improvements in survival have been achieved with the implementation of anti-CD20 immunotherapy and optimization of dose-intensive consolidation strategies. The applications of whole-exome sequencing, comparative genomic hybridization, transcriptional profiling, and examination of the tumor microenvironment, particularly in the context of clinical investigation, provide insights that create a roadmap for the development and implementation of novel targeted agents for this disease. A body of genetic evidence strongly suggested that primary CNS lymphomas (PCNSLs) are likely largely dependent on NF-κB prosurvival signals, with enrichment of mutations involving the B-cell receptor pathway, in particular myeloid differentiation primary response 88 and cluster of differentiation 79B. The first set of early-phase investigations that target NF-κB in PCNSL have now been completed and support the NF-κB hypothesis but at the same time reveal that much work needs to be done to translate these results into meaningful advances in survival for a large fraction of patients. Insights into secondary prosurvival pathways that mediate drug resistance is a priority for investigation. Similarly, further evaluation of the immune-suppressive mechanisms in the CNS lymphoma tumor microenvironment is requisite for progress. Combinatorial interventions that promote the antitumor immune response have significant potential. With increasing availability of targeted agents, there is also a need to develop more sensitive imaging tools, not only to detect this highly invasive brain neoplasm but also potentially to define an evolving molecular phenotype to facilitate precision medicine.

The Challenge of Primary Central Nervous System Lymphoma

Primary central nervous system (CNS) lymphoma is a challenging subtypes of aggressive non-Hodgkin lymphoma. Emerging clinical data suggest that optimized outcomes are achieved with dose-intensive CNS-penetrant chemotherapy and avoiding whole brain radiotherapy. Anti-CD20 antibody-based immunotherapy as a component of high-dose methotrexate-based induction programs may contribute to improved outcomes. An accumulation of insights into the molecular and cellular basis of disease pathogenesis is providing a foundation for the generation of molecular tools to facilitate diagnosis as well as a roadmap for integration of targeted therapy within the developing therapeutic armamentarium for this challenging brain tumor.

Functional consequences of I56ii Dlx enhancer deletion in the developing mouse forebrain

Dlx homeobox genes encode a group of transcription factors that play an essential role during developmental processes including maintaining the differentiation, proliferation and migration of GABAergic interneurons. The Dlx1/2 and Dlx5/6 genes are expressed in the forebrain and are arranged in convergently transcribed bigene clusters, with I12a/I12b and I56i/I56ii cis-regulatory elements (CREs) located in the intergenic region of each cluster respectively. We have characterized the phenotypic consequences of deleting I56ii on forebrain development and spatial patterning of corridor cells that are involved in guiding thalamocortical projections. Here we report that deletion of I56ii impairs expression of Dlx genes and that of potential targets including Gad2 as well as striatal markers Islet1, Meis2, and Ebf1. In addition, I56ii deletion reduces both the binding of DLX2 in the Dlx5/Dlx6 intergenic region and the presence of H3K9Ac at the Dlx5/Dlx6 locus, consistent with the reduced expression of these genes. Deletion of I56ii reduces the expression of the ISLET1 and CTIP2 in the striatum and disrupts the number of parvalbumin and calretinin expressing cells in the adult somatosensory cortex of the ΔI56ii mice. These data suggest an important regulatory role for I56ii in the developing forebrain by means of a potential regulatory mechanism which may regulate the expression of Dlx genes, notably Dlx6 as well as the spatial patterning of the ventral telencephalon, including possibly corridor cells.

Long-term survival in AIDS-related primary central nervous system lymphoma

BACKGROUND

The optimal therapeutic approach for patients with AIDS-related primary central nervous system lymphoma (AR-PCNSL) remains undefined. While its incidence declined substantially with combination antiretroviral therapy (cART), AR-PCNSL remains a highly aggressive neoplasm for which whole brain radiotherapy (WBRT) is considered a standard first-line intervention.

METHODS

To identify therapy-related factors associated with favorable survival, we first retrospectively analyzed outcomes of AR-PCNSL patients treated at San Francisco General Hospital, a public hospital with a long history of dedicated care for patients with HIV and AIDS-related malignancies. Results were validated in a retrospective, multicenter analysis that evaluated all newly diagnosed patients with AR-PCNSL treated with cART plus high-dose methotrexate (HD-MTX).

RESULTS

We provide evidence that CD4+ reconstitution with cART administered during HD-MTX correlates with long-term survival among patients with CD4 <100. This was confirmed in a multicenter analysis which demonstrated that integration of cART regimens with HD-MTX was generally well tolerated and resulted in longer progression-free survival than other treatments. No profound differences in immunophenotype were identified in an analysis of AR-PCNSL tumors that arose in the pre- versus post-cART eras. However, we detected evidence for a demographic shift, as the proportion of minority patients with AR-PCNSL increased since advent of cART.

CONCLUSION

Long-term disease-free survival can be achieved in AR-PCNSL, even among those with histories of opportunistic infections, limited access to health care, and medical non-adherence. Given this, as well as the long-term toxicities of WBRT, we recommend that integration of cART plus first-line HD-MTX be considered for all patients with AR-PCNSL.

New approaches in primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) has long been associated with an inferior prognosis compared to other aggressive non-Hodgkin's lymphomas (NHLs). However, during the past 10 years an accumulation of clinical experience has demonstrated that long-term progression-free survival (PFS) can be attained in a major proportion of PCNSL patients who receive dose-intensive consolidation chemotherapy and avoid whole brain radiotherapy. One recent approach that has reproducibly demonstrated efficacy for newly diagnosed PCNSL patients is an immunochemotherapy combination regimen used during induction that consists of methotrexate, temozolomide, and rituximab followed by consolidative infusional etoposide plus high-dose cytarabine (EA), administered in first complete remission (CR). Other high-dose chemotherapy-based consolidative regimens have shown efficacy as well. Our goal in this review is to update principles of diagnosis and management as well as data regarding the molecular pathogenesis of PCNSL, information that may constitute a basis for development of more effective therapies required to make additional advances in this phenotype of aggressive NHL.

The Combined Performance of ADC, CSF CXC Chemokine Ligand 13, and CSF Interleukin 10 in the Diagnosis of Central Nervous System Lymphoma

BACKGROUND AND PURPOSE

CXC chemokine ligand 13 and interleukin 10 have emerged as CSF biomarkers for the diagnosis of CNS lymphoma. Our hypothesis is that the combined use of ADC, CXC chemokine ligand 13, and interleukin 10 will result in increased diagnostic performance compared with the use of ADC values alone.

MATERIALS AND METHODS

Eighty-seven patients were included in this study, including 43 with CNS lymphoma and 44 without CNS lymphoma (21 metastases, 14 high-grade gliomas, 9 tumefactive demyelinating lesions) who had undergone CSF proteomic analysis and had a new enhancing mass on brain MR imaging. Average ADC was derived by contouring the contrast-enhancing tumor volume. Group means were compared via t tests for average ADC, CXC chemokine ligand 13, and interleukin 10. Receiver operating characteristic analysis was performed for each individual variable. Multiple-variable logistic regression with receiver operating characteristic analysis was performed, and the multiple-variable receiver operating characteristic was compared with single-variable receiver operating characteristics.

RESULTS

The average ADC was lower and CSF CXC chemokine ligand 13 and interleukin 10 values were higher in CNS lymphoma (P < .001). Areas under the curve ranged from 0.739 to 0.832 for single-variable ROC. Multiple-variable logistic regression yielded statistically significant individual effects for all 3 variables in a combined model. Multiple-variable receiver operating characteristics (area under the curve, 0.928) demonstrated statistically significantly superior diagnostic performance compared with the use of single variables alone.

CONCLUSIONS

The combined use of ADC, CSF CXC chemokine ligand 13, and interleukin 10 results in increased diagnostic performance for the diagnosis of CNS lymphoma. This finding highlights the importance of CSF analysis when the diagnosis of CNS lymphoma is considered on the basis of MR imaging.

Prolonged Complete Response in a Pediatric Patient With Primary Peripheral T-Cell Lymphoma of the Central Nervous System

We describe a child with a 2-week history of progressive headaches, blurry vision, and intermittent vomiting. Magnetic resonance imaging (MRI) of the brain showed a deep left hemispheric lesion with extension into the corpus callosum. Histology and immunophenotyping of the lesion was consistent with peripheral T-cell lymphoma, not otherwise specified. Chemotherapy was initiated and a complete remission was achieved. This case illustrates that a chemotherapeutic regimen used in adults with central nervous system (CNS) lymphoma can achieve durable remissions in pediatric patients with peripheral T-cell lymphoma, not otherwise specified of the CNS.

Progress in central nervous system lymphomas

Until recently, primary central nervous system lymphoma (PCNSL) was associated with a uniformly dismal prognosis. It is now reasonable to anticipate long-term survival and possibly cure for a significant proportion of patients diagnosed with PCNSL. Accumulated data generated over the past 10 years has provided evidence that long-term progression-free survival (PFS) can reproducibly be attained in a significant fraction of PCNSL patients that receive dose-intensive chemotherapy consolidation, without whole brain radiotherapy. One consolidative regimen that has reproducibly demonstrated promise is the combination of infusional etoposide plus high-dose cytarabine (EA), administered in first complete remission after methotrexate, temozolomide and rituximab-based induction. Given evolving principles of management and the mounting evidence for reproducible improvements in survival rates in prospective clinical series, our goal in this review is to highlight and update principles in diagnosis, staging and management as well as to review data regarding the pathogenesis of central nervous system lymphomas, information that is likely to constitute a basis for the implementation of novel therapies that are requisite for further progress in this unique phenotype of non-Hodgkin lymphoma.

Beyond high-dose methotrexate and brain radiotherapy: novel targets and agents for primary CNS lymphoma

BACKGROUND

While there has been significant progress in outcomes for patients diagnosed with primary central nervous system (CNS) lymphoma (PCNSL), survival rates will likely plateau with the current armamentarium of agents used to treat these patients. Moreover, given that PCNSL increasingly impacts an older population, a significant proportion of patients are not eligible for intensive therapies such as high-dose chemotherapy or whole-brain radiation. There is a need for the development of novel agents, which target key survival pathways in order to continue to make progress in this disease.

PATIENTS AND METHODS

We reviewed the key molecular pathways and genomic aberrations in PCNSL in order to identify candidate targets. We focused on molecules and pathways that have been identified and confirmed by more than one investigator or methodology.

RESULTS

While PCNSL tumors usually express a BCL6+, MUM1+ 'activated, germinal center' immunophenotype, they exhibit multiple shared genetic properties with ABC-type diffuse large B-cell lymphomas. Candidate targets and pathways include NFkB, the B-cell receptor, the JAK/STAT pathway, IRF4, BCL-6 as well as PIM kinases. Elements of the tumor microenvironment that may be exploited therapeutically include chemokine pathways, as well as macrophage and T-cell responses.

CONCLUSIONS

There is a significant need for developing novel therapies in PCNSL, given that an increasing proportion of patients are not eligible for high-dose chemotherapy and brain radiation is associated with detrimental cognitive side-effects. We provide an overview of potential drug targets and novel agents that may be integrated with existing strategies in order to make further progress in this disease.

Complement activation and intraventricular rituximab distribution in recurrent central nervous system lymphoma

PURPOSE

To elucidate the mechanistic basis for efficacy of intrathecal rituximab. We evaluated complement activation as well as the pharmacokinetics of intraventricular rituximab in patients who participated in two phase 1 multicenter studies.

EXPERIMENTAL DESIGN

We evaluated complement activation as a candidate mediator of rituximab within the central nervous system (CNS). Complement C3 and C5b-9 were quantified by ELISA in serial cerebrospinal fluid (CSF) specimens after intraventricular rituximab administration. We determined rituximab concentration profiles in CSF and serum. A population three- compartment pharmacokinetic model was built to describe the disposition of rituximab following intraventricular administration. The model was derived from results of the first trial and validated with results of the second trial.

RESULTS

Complement C3 and C5b-9 were reproducibly activated in CSF after intraventricular rituximab. Ectopic expression of C3 mRNA and protein within CNS lymphoma lesions was localized to myeloid cells. Constitutive high C3 activation at baseline was associated with adverse prognosis. A pharmacokinetic model was built, which contains three distinct compartments, to describe the distribution of rituximab within the neuroaxis after intraventricular administration.

CONCLUSIONS

We provide the first evidence of C3 activation within the neuroaxis with intraventricular immunotherapy and suggest that complement may contribute to immunotherapeutic responses of rituximab in CNS lymphoma. Penetration of rituximab into neural tissue is supported by this pharmacokinetic model and may contribute to efficacy. These findings have general implications for intraventricular immunotherapy. Our data highlight potential innovations to improve efficacy of intraventricular immunotherapy both via modulation of the innate immune response as well as innovations in drug delivery.

A systematic approach to the diagnosis of suspected central nervous system lymphoma

Central nervous system (CNS) lymphoma can present a diagnostic challenge. Currently, there is no consensus regarding what presurgical evaluation is warranted or how to proceed when lesions are not surgically accessible. We conducted a review of the literature on CNS lymphoma diagnosis (1966 to October 2011) to determine whether a common diagnostic algorithm can be generated. We extracted data regarding the usefulness of brain and body imaging, serum and cerebrospinal fluid (CSF) studies, ophthalmologic examination, and tissue biopsy in the diagnosis of CNS lymphoma. Contrast enhancement on imaging is highly sensitive at the time of diagnosis: 98.9% in immunocompetent lymphoma and 96.1% in human immunodeficiency virus-related CNS lymphoma. The sensitivity of CSF cytology is low (2%-32%) but increases when combined with flow cytometry. Cerebrospinal fluid lactate dehydrogenase isozyme 5, β2-microglobulin, and immunoglobulin heavy chain rearrangement studies have improved sensitivity over CSF cytology (58%-85%) but have only moderate specificity (85%). New techniques of proteomics and microRNA analysis have more than 95% specificity in the diagnosis of CNS lymphoma. Positive CSF cytology, vitreous biopsy, or brain/leptomeningeal biopsy remain the current standard for diagnosis. A combined stepwise systematic approach outlined here may facilitate an expeditious, comprehensive presurgical evaluation for cases of suspected CNS lymphoma.

Intensive chemotherapy and immunotherapy in patients with newly diagnosed primary CNS lymphoma: CALGB 50202 (Alliance 50202)

PURPOSE

Concerns regarding neurocognitive toxicity of whole-brain radiotherapy (WBRT) have motivated development of alternative, dose-intensive chemotherapeutic strategies as consolidation in primary CNS lymphoma (PCNSL). We performed a multicenter study of high-dose consolidation, without WBRT, in PCNSL. Objectives were to determine: one, rate of complete response (CR) after remission induction therapy with methotrexate, temozolomide, and rituximab (MT-R); two, feasibility of a two-step approach using high-dose consolidation with etoposide plus cytarabine (EA); three, progression-free survival (PFS); and four, correlation between clinical and molecular prognostic factors and outcome.

PATIENTS AND METHODS

Forty-four patients with newly diagnosed PCNSL were treated with induction MT-R, and patients who achieved CR received EA consolidation. We performed a prospective analysis of molecular prognostic biomarkers in PCNSL in the setting of a clinical trial.

RESULTS

The rate of CR to MT-R was 66%. The overall 2-year PFS was 0.57, with median follow-up of 4.9 years. The 2-year time to progression was 0.59, and for patients who completed consolidation, it was 0.77. Patients age > 60 years did as well as younger patients, and the most significant clinical prognostic variable was treatment delay. High BCL6 expression correlated with shorter survival.

CONCLUSION

CALGB 50202 demonstrates for the first time to our knowledge that dose-intensive consolidation for PCNSL is feasible in the multicenter setting and yields rates of PFS and OS at least comparable to those of regimens involving WBRT. On the basis of these encouraging results, an intergroup study has been activated comparing EA consolidation with myeloablative chemotherapy in this randomized trial in PCNSL, in which neither arm involves WBRT.

Combined diffusion and perfusion MR imaging as biomarkers of prognosis in immunocompetent patients with primary central nervous system lymphoma

BACKGROUND AND PURPOSE

ADC derived from DWI has been shown to correlate with PFS and OS in immunocompetent patients with PCNSL. The purpose of our study was to confirm the validity of ADC measurements as a prognostic biomarker and to determine whether rCBV measurements derived from DSC perfusion MR imaging provide prognostic information.

MATERIALS AND METHODS

Pretherapy baseline DWI and DSC perfusion MR imaging in 25 patients with PCNSL was analyzed before methotrexate-based induction chemotherapy. Contrast-enhancing tumor was segmented and coregistered with ADC and rCBV maps, and mean and minimum values were measured. Patients were separated into high or low ADC groups on the basis of previously published threshold values of ADC(min) < 384 × 10(-6) mm(2)/s. High and low rCBV groups were defined on the basis of receiver operating curve analysis. High and low ADC and rCBV groups were analyzed independently and in combination. Multivariate Cox survival analysis was performed.

RESULTS

Patients with ADC(min) values < 384 × 10(-6) mm(2)/s or rCBV(mean) values < 1.43 had worse PFS and OS. The patient cohort with combined low ADC(min)-low rCBV(mean) had the worst prognosis. No other variables besides ADC and rCBV significantly affected survival.

CONCLUSIONS

Our study reinforces the validity of ADC values as a prognostic biomarker and provides the first evidence of low tumor rCBV as a novel risk factor for adverse prognosis in immunocompetent patients with PCNSL.

Immunochemotherapy with intensive consolidation for primary CNS lymphoma: a pilot study and prognostic assessment by diffusion-weighted MRI

PURPOSE

We evaluated a novel therapy for primary central nervous system lymphoma (PCNSL) with induction immunochemotherapy with high-dose methotrexate, temozolomide, and rituximab (MT-R) followed by intensive consolidation with infusional etoposide and high-dose cytarabine (EA). In addition, we evaluated the prognostic value of the minimum apparent diffusion coefficient (ADC(min)) derived from diffusion-weighted MRI (DW-MRI) in patients treated with this regimen.

EXPERIMENTAL DESIGN

Thirty-one patients (median age, 61 years; median Karnofsky performance score, 60) received induction with methotrexate every 14 days for 8 planned cycles. Rituximab was administered the first 6 cycles and temozolomide administered on odd-numbered cycles. Patients with responsive or stable central nervous system (CNS) disease received EA consolidation. Pretreatment DW-MRI was used to calculate the ADC(min) of contrast-enhancing lesions.

RESULTS

The complete response rate for MT-R induction was 52%. At a median follow-up of 79 months, the 2-year progression-free and overall survival were 45% and 58%, respectively. For patients receiving EA consolidation, the 2-year progression-free and overall survival were 78% and 93%, respectively. EA consolidation was also effective in an additional 3 patients who presented with synchronous CNS and systemic lymphoma. Tumor ADC(min) less than 384 × 10(-6) mm(2)/s was significantly associated with shorter progression-free and overall survival.

CONCLUSIONS

MT-R induction was effective and well tolerated. MT-R followed by EA consolidation yielded progression-free and overall survival outcomes comparable to regimens with chemotherapy followed by whole-brain radiotherapy consolidation but without evidence of neurotoxicity. Tumor ADC(min) derived from DW-MRI provided better prognostic information for PCNSL patients treated with the MTR-EA regimen than established clinical risk scores.

Primary vitreoretinal lymphoma: a report from an International Primary Central Nervous System Lymphoma Collaborative Group symposium

Primary vitreoretinal lymphoma (PVRL), also known as primary intraocular lymphoma, is a rare malignancy typically classified as a diffuse large B-cell lymphoma and most frequently develops in elderly populations. PVRL commonly masquerades as posterior uveitis and has a unique tropism for the retina and central nervous system (CNS). Over 15% of primary CNS lymphoma patients develop intraocular lymphoma, usually occurring in the retina and/or vitreous. Conversely, 65%-90% of PVRL patients develop CNS lymphoma. Consequently, PVRL is often fatal because of ultimate CNS association. Current PVRL animal models are limited and require further development. Typical clinical findings include vitreous cellular infiltration (lymphoma and inflammatory cells) and subretinal tumor infiltration as determined using dilated fundoscopy, fluorescent angiography, and optical coherent tomography. Currently, PVRL is most often diagnosed using both histology to identify lymphoma cells in the vitreous or retina and immunohistochemistry to indicate monoclonality. Additional adjuncts in diagnosing PVRL exist, including elevation of interleukin-10 levels in ocular fluids and detection of Ig(H) or T-cell receptor gene rearrangements in malignant cells. The optimal therapy for PVRL is not defined and requires the combined effort of oncologists and ophthalmologists. PVRL is sensitive to radiation therapy and exhibits high responsiveness to intravitreal methotrexate or rituximab. Although systemic chemotherapy alone can result in high response rates in patients with PVRL, there is a high relapse rate. Because of the disease rarity, international, multicenter, collaborative efforts are required to better understand the biology and pathogenesis of PVRL as well as to define both diagnostic markers and optimal therapies.

Primary vitreoretinal lymphoma: a report from an International Primary Central Nervous System Lymphoma Collaborative Group symposium

Primary vitreoretinal lymphoma (PVRL), also known as primary intraocular lymphoma, is a rare malignancy typically classified as a diffuse large B-cell lymphoma and most frequently develops in elderly populations. PVRL commonly masquerades as posterior uveitis and has a unique tropism for the retina and central nervous system (CNS). Over 15% of primary CNS lymphoma patients develop intraocular lymphoma, usually occurring in the retina and/or vitreous. Conversely, 65%-90% of PVRL patients develop CNS lymphoma. Consequently, PVRL is often fatal because of ultimate CNS association. Current PVRL animal models are limited and require further development. Typical clinical findings include vitreous cellular infiltration (lymphoma and inflammatory cells) and subretinal tumor infiltration as determined using dilated fundoscopy, fluorescent angiography, and optical coherent tomography. Currently, PVRL is most often diagnosed using both histology to identify lymphoma cells in the vitreous or retina and immunohistochemistry to indicate monoclonality. Additional adjuncts in diagnosing PVRL exist, including elevation of interleukin-10 levels in ocular fluids and detection of Ig(H) or T-cell receptor gene rearrangements in malignant cells. The optimal therapy for PVRL is not defined and requires the combined effort of oncologists and ophthalmologists. PVRL is sensitive to radiation therapy and exhibits high responsiveness to intravitreal methotrexate or rituximab. Although systemic chemotherapy alone can result in high response rates in patients with PVRL, there is a high relapse rate. Because of the disease rarity, international, multicenter, collaborative efforts are required to better understand the biology and pathogenesis of PVRL as well as to define both diagnostic markers and optimal therapies.

Abstract 2728: Multivariate analysis of cerebrospinal fluid protein biomarkers in central nervous system lymphoma patients and controls

Establishing the diagnosis of primary central nervous system lymphoma (PCNSL) is often difficult as the clinical presentation and radiographic features are nonspecific. The gold standards for diagnosis are cytologic analysis of the CSF, which has poor sensitivity, or brain biopsy, which may be associated with significant morbidity and a high rate of diagnostic failure. We are testing the hypothesis that the cerebrospinal fluid (CSF) proteome contains information which may facilitate early and noninvasive diagnosis of CNS lymphoma as well as provide prognostic information.

We evaluated the CSF concentrations of three candidate CNS lymphoma protein biomarkers: CXCL-13, a B-cell homing chemokine, Interleukin-10 (IL-10), an autocrine B-cell growth factor, and antithrombin-III (ATIII), a candidate tumor biomarker which we previously identified by mass spectrometric analysis of the CSF.

Determinations were performed by ELISA of CSF diagnostic specimens from 228 patients: 75 specimens were from patients with a confirmed diagnosis of non-Hodgkin's lymphoma of the brain and 153 controls including 15 specimens from patients with astrocytic neoplasms, 16 specimens from secondary brain tumors including metastases from breast and lung cancer, and 122 other controls including patients with established systemic lymphoma who staged negative for CNS involvement. Mean concentrations of CXCL-13, IL-10 and ATIII were each significantly elevated in the CSF of CNS lymphoma patients compared to the controls (p&lt;0.0003). By contrast, mean CSF albumin concentration, measured to control for disruption of the blood-brain barrier in the two groups, was similar in CNS lymphoma versus controls (p=0.17). The potential utility of each of these candidate biomarkers for CNS lymphoma was evaluated by means of receiver operating characteristic (ROC) curve analysis, both individually as well as in combination. Bivariate determination of CXCL-13 and IL-10 concentrations yield the best potential discrimination of CNS lymphoma versus all other controls. Detection of IL-10 in combination with CXCL-13 in CSF identified CNS lymphoma with the highest accuracy with area under the ROC curve equal to 0.858 (79% sensitivity and 92.2% specificity), (p&lt;0.0001). In addition, we noted a potential relationship between high CSF concentration of CXCL-13 and short survival at first relapse.

These preliminary data support a role for CXCL-13 and IL-10 in the pathogenesis of B-cell non-Hodgkin's lymphoma involving the brain and support our hypothesis that molecular signals within the CSF may be rapidly evaluated in combination to facilitate early and relatively non-invasive diagnosis. This approach may also be applied with other diagnostic modalities such as neuroimaging and flow-cytometry.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2728.

Abstract 5580: Macrophage polarization and acquired resistance to rituximab in CNS lymphoma

Macrophages are a critical component of anti-tumor immunity but may be subverted from an M1 phenotype, which mediates tumor elimination, to an M2 phenotype, which promotes tumor progression. IL-4 signaling is a pivotal regulator of macrophage polarization to the M2 phenotype; we have recently demonstrated the intratumoral expression of IL-4 in CNS lymphoma (Blood, 2006; CCR, 2009).

Rituximab efficacy appears to be mediated predominantly by ADCC, with tumor-associated macrophages being the dominant effector cell. We hypothesize that the phenotype of tumor-associated macrophages (M1 vs. M2) may be a determinant of rituximab efficacy and resistance.

There is an extreme paucity of information regarding the role and phenotype of macrophages in non-Hodgkin lymphoma (NHL), including CNS lymphoma. We have developed a novel flow-cytometry-based approach for the isolation and characterization of macrophages from the cerebrospinal fluid (CSF) of patients with CNS NHL. Our gene expression studies of CD14+ activated CSF macrophages suggested two candidate markers of M2 differentiation, CD206 and Factor XIII. M1 differentiation was identified using DAF-FM diacetate, a cell-permeable marker of nitric oxide synthase (iNOS). Our results suggest the presence of at least four distinct subpopulations of activated macrophages in CSF based upon the relative expression of these markers.

CSF macrophage subpopulations were characterized and sorted from 42 subjects: 22 immunocompetent patients with CNS NHL and 20 control subjects with non-neoplastic conditions. Our data suggest an association of M2 macrophages in the CSF with the pathogenesis of CNS NHL: a greater than six-fold increase in the proportion of macrophages with M2 features was detected in CSF from CNS NHL subjects compared to controls (p&lt;0.001). By contrast, the proportion of macrophages with M1 features was similar between NHL and controls. Intraventricular administration of rituximab was reproducibly associated with a greater than three-fold increase in the relative ratio of M2:M1 macrophages in the CSF of patients with recurrent CNS NHL (p&lt;0.001), usually within two weeks of administration. By contrast, intra-CSF administration of methotrexate (MTX) was associated with an increased ratio of M1:M2 macrophages (within 96h). In each of five patients participating in a Phase I clinical trial involving intrathecal rituximab plus MTX, increased M2 macrophage polarization anticipated the onset of rituximab resistance and tumor progression.

We believe this to be the first application of flow-cytometry to define the phenotypes of intratumoral macrophages in NHL as well as the first description of dynamic changes in macrophage phenotypes during the evolution of resistance to rituximab therapy. The elucidation of distinct macrophage subpopulations based upon the expression of candidate markers of M1 vs. M2 phenotypes may provide insight into tumor pathogenesis and prognosis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5580.

Diffusion-weighted MR imaging derived apparent diffusion coefficient is predictive of clinical outcome in primary central nervous system lymphoma

BACKGROUND AND PURPOSE

There is evidence that increased tumor cellular density within diagnostic specimens of primary central nervous system lymphoma (PCNSL) may have significant prognostic implications. Because cellular density may influence measurements of apparent diffusion coefficient (ADC) by using diffusion-weighted MR imaging (DWI), we hypothesized that ADC measured from contrast-enhancing regions might correlate with clinical outcome in patients with PCNSL.

MATERIALS AND METHODS

PCNSL tumors from 18 immunocompetent patients, treated uniformly with methotrexate-based chemotherapy, were studied with pretherapeutic DWI. Enhancing lesions were diagnosed by pathologic analysis as high-grade B-cell lymphomas. Regions of interest were placed around all enhancing lesions allowing calculation of mean, 25th percentile (ADC(25%)), and minimum ADC values. Histopathologic tumor cellularity was quantitatively measured in all patients. High and low ADC groups were stratified by the median ADC value of the cohort. The Welch t test assessed differences between groups. The Pearson correlation examined relationships between ADC measurements and tumor cellular density. Single and multivariable survival analysis was performed.

RESULTS

We detected significant intra- and intertumor heterogeneity in ADC measurements. An inverse correlation between cellular density and ADC measurements was observed (P < .05). ADC(25%) measurements less than the median value of 692 (low ADC group) were associated with significantly shorter progression-free and overall survival. Patients with improved clinical outcome were noted to exhibit a significant decrease in ADC measurements following high-dose methotrexate chemotherapy.

CONCLUSIONS

Our study provides evidence that ADC measurements within contrast-enhancing regions of PCNSL tumors may provide noninvasive insight into clinical outcome.

Biology and treatment of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare variant of extranodal non-Hodgkin lymphoma that is restricted in distribution to the brain, leptomeninges, spinal cord, and intraocular compartments. Although PCNSL shares overlapping features with systemic lymphoma, recent studies also reveal a unique pattern of gene and protein expression in PCNSL. These findings have yielded new insights into the pathophysiology of the disease, as well as the identification of novel prognostic biomarkers. Immune system compromise, such as is seen in acquired immune deficiency syndrome (AIDS), is the best established known risk factor for PCNSL. Like other lesions of the brain, meninges, and eye, the presenting symptoms associated with PCNSL typically include focal neurological deficits related to the site of disease or more global consequences of increased intracranial pressure. Diagnosis of PCNSL typically includes gadolinium-enhanced MRI and pathologic tissue analysis, as well as additional studies aimed at excluding concurrent systemic disease. PCNSL typically has a worse overall prognosis than systemic lymphoma. High-dose chemotherapy, particularly with methotrexate-based regimens, is the backbone of therapy for most patients, and chemotherapy is associated with much lower rates of treatment-related morbidity and mortality than whole-brain irradiation. Autologous stem cell transplantation is an emerging treatment modality, particularly in younger patients with relapsed disease, but high rates of treatment-related mortality are observed in older patients. Immunotherapy, including treatment with intrathecal rituximab, is another area of active research that may have promise in refractory or relapsed disease. Treatment options for intraocular lymphoma parallel those for PCNSL elsewhere in the brain: systemic chemotherapy, radiation, and local delivery of cytotoxic and immunologically active agents such as anti-CD20 antibody.

Insights into the biology of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare variant of non-Hodgkin lymphoma that is confined to the central nervous system. Biologic studies of PCNSL are challenging to conduct because the disease is rare and available tissue material is sparse. However, in recent years there has been progress in the understanding of PCNSL biology, largely as the result of multicenter studies using modern molecular techniques. Recent studies may improve insight into the pathogenesis of PCNSL and increase the chances of identifying prognostic factors and novel therapeutic targets. This review discusses recent advances in PCNSL biology, including immunologic and genetic risk factors, and focuses on the molecular alterations important in central nervous system lymphomagenesis.

Pathologic correlates of primary central nervous system lymphoma defined in an orthotopic xenograft model

PURPOSE

The prospect for advances in the treatment of patients with primary central nervous system lymphoma (PCNSL) is likely dependent on the systematic evaluation of its pathobiology. Animal models of PCNSL are needed to facilitate the analysis of its molecular pathogenesis and for the efficient evaluation of novel therapeutics.

EXPERIMENTAL DESIGN

We characterized the molecular pathology of CNS lymphoma tumors generated by the intracerebral implantation of Raji B lymphoma cells in athymic mice. Lymphoma cells were modified for bioluminescence imaging to facilitate monitoring of tumor growth and response to therapy. In parallel, we identified molecular features of lymphoma xenograft histopathology that are evident in human PCNSL specimens.

RESULTS

Intracerebral Raji tumors were determined to faithfully reflect the molecular pathogenesis of PCNSL, including the predominant immunophenotypic state of differentiation of lymphoma cells and their reactive microenvironment. We show the expression of interleukin-4 by Raji and other B lymphoma cell lines in vitro and by Raji tumors in vivo and provide evidence for a role of this cytokine in the M2 polarization of lymphoma macrophages both in the murine model and in diagnostic specimens of human PCNSL.

CONCLUSION

Intracerebral implantation of Raji cells results in a reproducible and invasive xenograft model, which recapitulates the histopathology and molecular features of PCNSL, and is suitable for preclinical testing of novel agents. We also show for the first time the feasibility and accuracy of tumor bioluminescence in the monitoring of a highly infiltrative brain tumor.