Rare Primary Central Nervous System Tumors in Adults: An Overview

Overall, tumors of primary central nervous system (CNS) are quite common in adults with an incidence rate close to 30 new cases/100,000 inhabitants per year. Significant clinical and biological advances have been accomplished in the most common adult primary CNS tumors (i.e., diffuse gliomas). However, most CNS tumor subtypes are rare with an incidence rate below the threshold defining rare disease of 6.0 new cases/100,000 inhabitants per year. Close to 150 entities of primary CNS tumors have now been identified by the novel integrated histomolecular classification published by the World Health Organization (WHO) and its updates by the c-IMPACT NOW consortium (the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy). While these entities can be better classified into smaller groups either by their histomolecular features and/or by their location, assessing their treatment by clinical trials and improving the survival of patients remain challenging. Despite these tumors are rare, research, and advances remain slower compared to diffuse gliomas for instance. In some cases (i.e., ependymoma, medulloblastoma) the understanding is high because single or few driver mutations have been defined. The European Union has launched European Reference Networks (ERNs) dedicated to support advances on the clinical side of rare diseases including rare cancers. The ERN for rare solid adult tumors is termed EURACAN. Within EURACAN, Domain 10 brings together the European patient advocacy groups (ePAGs) and physicians dedicated to improving outcomes in rare primary CNS tumors and also aims at supporting research, care and teaching in the field. In this review, we discuss the relevant biological and clinical characteristics, clinical management of patients, and research directions for the following types of rare primary CNS tumors: medulloblastoma, pineal region tumors, glioneuronal and rare glial tumors, ependymal tumors, grade III meningioma and mesenchymal tumors, primary central nervous system lymphoma, germ cell tumors, spinal cord tumors and rare pituitary tumors.

Use of FDG-PET/CT for systemic assessment of suspected primary central nervous system lymphoma: a LOC study

INTRODUCTION

Primary Central Nervous System Lymphoma (PCNSL) is a rare disease with different therapeutic implications than systemic lymphoma. In this study, we evaluated whole-body ¹⁸FDG-PET/CT for pre-chemotherapy imaging of suspected PCNSL.

METHODS

One hundred and thirty consecutive immunocompetent patients were retrospectively included. The results of initial ¹⁸FDG-PET/CT, contrast-enhanced CT (CeCT) and bone marrow biopsy (BMB) when available were compared to a gold standard based on pathological diagnosis or follow-up.

RESULTS

CNS lesion pathology showed large B-cell lymphoma in 95% of patients, including 11 patients with primary vitro-retinal lymphoma. Ten patients (8%) where ultimately diagnosed with systemic lymphoma involvement, including five pathologically confirmed cases, all of which were detected by ¹⁸FDG-PET/CT. ¹⁸FDG-PET/CT showed incidental systemic findings unrelated to lymphoma in 14% of patients. An SUVmax threshold of nine enabled good discrimination between systemic lymphoma and other lesions (sensitivity 92% and specificity 89%). CeCT and BMB performed in 108 and 77 patients respectively revealed systemic lesions in only three patients.

CONCLUSION

¹⁸FDG-PET/CT detected concomitant occult systemic involvement in a non-negligible proportion of suspected PCNSL cases (8%). In this setting its sensitivity is higher than that of CeCT. All of our patients ultimately diagnosed with concomitant systemic involvement had positive ¹⁸FDG-PET/CT. We believe it constitutes a safe one-stop shop evaluation for the systemic pre-treatment imaging of suspected PCNSL.

Mechanisms and therapeutic implications of hypermutation in gliomas

A high tumour mutational burden (hypermutation) is observed in some gliomas1-5; however, the mechanisms by which hypermutation develops and whether it predicts the response to immunotherapy are poorly understood. Here we comprehensively analyse the molecular determinants of mutational burden and signatures in 10,294 gliomas. We delineate two main pathways to hypermutation: a de novo pathway associated with constitutional defects in DNA polymerase and mismatch repair (MMR) genes, and a more common post-treatment pathway, associated with acquired resistance driven by MMR defects in chemotherapy-sensitive gliomas that recur after treatment with the chemotherapy drug temozolomide. Experimentally, the mutational signature of post-treatment hypermutated gliomas was recapitulated by temozolomide-induced damage in cells with MMR deficiency. MMR-deficient gliomas were characterized by a lack of prominent T cell infiltrates, extensive intratumoral heterogeneity, poor patient survival and a low rate of response to PD-1 blockade. Moreover, although bulk analyses did not detect microsatellite instability in MMR-deficient gliomas, single-cell whole-genome sequencing analysis of post-treatment hypermutated glioma cells identified microsatellite mutations. These results show that chemotherapy can drive the acquisition of hypermutated populations without promoting a response to PD-1 blockade and supports the diagnostic use of mutational burden and signatures in cancer.

Management and outcome of primary CNS lymphoma in the modern era: An LOC network study

OBJECTIVE

Real-life studies on patients with primary CNS lymphoma (PCNSL) are scarce. Our objective was to analyze, in a nationwide population-based study, the current medical practice in the management of PCNSL.

METHODS

The French oculo-cerebral lymphoma network (LOC) database prospectively records all newly diagnosed PCNSL cases from 32 French centers. Data of patients diagnosed between 2011 and 2016 were retrospectively analyzed.

RESULTS

We identified 1,002 immunocompetent patients (43% aged >70 years, median Karnofsky Performance Status [KPS] 60). First-line treatment was high-dose methotrexate-based chemotherapy in 92% of cases, with an increasing use of rituximab over time (66%). Patients <60 years of age received consolidation treatment in 77% of cases, consisting of whole-brain radiotherapy (WBRT) (54%) or high-dose chemotherapy with autologous stem cell transplantation (HCT-ASCT) (23%). Among patients >60 years of age, WBRT and HCT-ASCT consolidation were administered in only 9% and 2%, respectively. The complete response rate to initial chemotherapy was 50%. Median progression-free survival was 10.5 months. For relapse, second-line chemotherapy, HCT-ASCT, WBRT, and palliative care were offered to 55%, 17%, 10%, and 18% of patients, respectively. The median, 2-year, and 5-year overall survival was 25.3 months, 51%, and 38%, respectively (<60 years: not reached [NR], 70%, and 61%; >60 years: 15.4 months, 44%, and 28%). Age, KPS, sex, and response to induction CT were independent prognostic factors in multivariate analysis.

CONCLUSIONS

Our study confirms the increasing proportion of elderly within the PCNSL population and shows comparable outcome in this population-based study with those reported by clinical trials, reflecting a notable application of recent PCNSL advances in treatment.

Romiplostim for temozolomide-induced thrombocytopenia in glioblastoma: The PLATUM trial

OBJECTIVE

To determine the efficacy of the thrombopoietin receptor agonist romiplostim for the prevention of temozolomide-induced thrombocytopenia in newly diagnosed glioblastoma.

METHODS

In the PLATUM phase II open-label, multicenter, single-arm trial, patients diagnosed with Common Terminology Criteria for Adverse Events grade 3 or 4 thrombocytopenia during chemoradiotherapy received weekly subcutaneous romiplostim injections. PLATUM aimed at demonstrating that the percentage of thrombocytopenic patients treated with romiplostim able to complete 6 cycles of maintenance temozolomide chemotherapy exceeded 10% (p0 = 0.10; pA = 0.35). Using type I error equal to 0.05% and 95% power, 31 patients had to be recruited. According to a Fleming 2-step design with a preplanned interim analysis after recruitment of 20 patients (step 1), the trial was terminated early for success.

RESULTS

Twenty patients were enrolled in step 1. Median age was 61 years (range 33-73). Twelve patients received 6 temozolomide cycles, corresponding to a success rate of 60% (95% confidence interval 36%-81%). Four patients discontinued temozolomide because they did not respond to romiplostim, 2 for progression, and 2 for adverse events unrelated to romiplostim.

CONCLUSION

The thrombopoietin receptor agonist romiplostim improves exposure to chemotherapy in patients with glioblastoma experiencing temozolomide-induced thrombocytopenia.

CLINICALTRIALSGOV IDENTIFIER

NCT02227576.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with glioblastoma and thrombocytopenia, romiplostim is effective for the secondary prophylaxis of temozolomide-induced thrombocytopenia.

Optimization of CSF biological investigations for CNS lymphoma diagnosis

Diagnosis of lymphoma leptomeningeal dissemination is challenging and relies on a wide array of methods. So far, no consensus biological guidelines are available. This increases the chance of intra- and interpractice variations, despite the shared concern to perform the minimum amount of tests while preserving clinically relevant results.We evaluated a training cohort of 371 cerebrospinal fluid (CSF) samples from patients with putative lymphomatous central nervous system (CNS) localization using conventional cytology (CC), flow cytometry (FCM), molecular clonality assesment by PCR and cytokine quantification (CQ). This led us to propose a biological algorithm, which was then verified on a validation cohort of 197 samples. The samples were classified according to the clinical context and the results of each technique were compared. Using all four techniques was not useful for exclusion diagnosis of CNS lymphoma (CNSL), but they proved complementary for cases with suspected CNSL. This was particularly true for CQ in primary CNSL. Overall, diagnosis can be obtained with a two-step approach. The first step comprises CC and FCM, as results are available quickly and FCM is a sensitive method. Both PCR and CQ can be postponed and performed in a second step, depending on the results from the first step and the clinical context.The proposed algorithm missed none of the CNSL samples of the validation cohort. Moreover, applying this algorithm would have spared 30% of PCR tests and 20% of CQ over a one-year period, without compromising clinical management.

P14.73 Toxicity and outcomes of reduced-dose whole brain radiotherapy as consolidation treatment for patients with CNS lymphoma in real life setting

BACKGROUND

Optimal treatment strategy for newly diagnosed primary PCNSL remains controversial. The high risk of radio-induced late-delayed neurotoxicity in patients who achieve long-term disease control constrains the use of classical consolidation WBRT. So as to reduce side cognitive effects, Morris et al, reported a phase II study, to assess the efficacy and toxicity of consolidation reduced-dose (23.4Gy) WBRT (rdWBRT) for patients with complete response after high dose methotrexate based chemotherapy. The study reported a 2-year PFS rate for these patients of 77%, with no evidence of significant cognitive decline during the follow-up (FU) period. The aim of this retrospective study was to report toxicity and outcomes of rdWBRT, in patients < 60 years old with complete response (CR) after HD-MTX based chemotherapy, in real life setting, without selection bias.

MATERIAL AND METHODS

Patients were selected from the French LOC network database, a nationwide database centralizing since 2011 information from 28 different centers in France, representing the main centers involved in PCNSL management. Patients were retrospectively selected according to the following criteria: 1) Pathological diagnosis of diffuse large B cell PCNSL; 2) age>18 and <60 years; 3) immunocompetent status; 4) First line induction treatment based on high dose MTX (At least MTX>1.5 g/m2); 5) CR according to the IPCG criteria after first-line induction treatment. Patients should have received a rdWBRT (23.4Gy in 13 fractions of 1.8Gy).

RESULTS

Twenty seven patients, were included. The median FU from initial diagnosis was 28.5 months [9.6–50.7]. Median age was 50.2 years [25–60]. Median Karnofsky Performans Status (KPS) was 90% [40–100%]. Seventeen patients had a multi focal disease at diagnosis (meningeal involvement n=6, in ophthalmic involvement n=4). PFS rates were 85% IC95[76–100 %], 65% IC95 [45–85%] and 65% IC95 [45–85%] at 1, 2, and 3 years respectively. The OS rates were 100%, 90,5% IC95 [77–100%] and 85%IC95 [69–100%]. 8 patients relapsed, with a median time from radiotherapy to recurrence of 6.5months [2.4–17]. All recurrences were outside the initially involved site(s), and 62.5% of tumors recurred as multifocal disease. All patients received salvage treatment, including intensive chemotherapy with autologous stem cell transplantation in 4 cases. No acute grade III-IV toxicity related to rdWBRT was reported. Neuropsychological follow up was available for 14 patients with no cognitive impairment at last follow up.

CONCLUSION

This is the largest retrospective study evaluating outcomes of rdWBRT for PCNSL young patients with CR after HD-MTX chemotherapy. Real life setting data from this study are quite reassuring, and rdWBRT could be considered as an efficient and safe consolidation strategy in this population. We need a longer FU to confirm the absence of cognitive deterioration.

Ibrutinib monotherapy for relapse or refractory primary CNS lymphoma and primary vitreoretinal lymphoma: Final analysis of the phase II 'proof-of-concept' iLOC study by the Lymphoma study association (LYSA) and the French oculo-cerebral lymphoma (LOC) network

BACKGROUND

Primary central nervous system lymphomas (PCNSLs) are mainly diffuse large B-cell lymphomas (DLBCLs) of the non-germinal centre B-cell subtype, with unmet medical needs. This study aimed to evaluate the efficacy and toxicity of ibrutinib in DLBCL-PCNSL PATIENTS AND METHODS: This prospective, multicentre, phase II study involved patients with relapse or refractory(R/R) DLBCL-PCNSL or primary vitreoretinal lymphoma. The treatment consisted of ibrutinib (560 mg/day) until disease progression or unacceptable toxicity occurred. The primary outcome was the disease control (DC) rate after two months of treatment (P0 < 10%; P1 > 30%).

RESULTS

Fifty-two patients were recruited. Forty-four patients were evaluable for response. After 2 months of treatment, the DC was 70% in evaluable patients and 62% in the intent-to-treat analysis, including 10 complete responses (19%), 17 partial responses (33%) and 5 stable diseases (10%). With a median follow-up of 25.7 months (range, 0.7-30.5), the median progression-free and overall survivals were 4.8 months (95% confidence interval [CI]; 2.8-12.7) and 19.2 months (95% CI; 7.2-NR), respectively. Thirteen patients received ibrutinib for more than 12 months. Two patients experienced pulmonary aspergillosis with a favourable (n = 1) or fatal outcome (n = 1). Ibrutinib was detectable in the cerebrospinal fluid (CSF). The clinical response to ibrutinib seemed independent of the gene mutations in the BCR pathway.

CONCLUSION

Ibrutinib showed clinical activity in the brain, the CSF and the intraocular compartment and was tolerated in R/R PCNSL. The addition of ibrutinib to standard methotrexate-base induction chemotherapy will be further evaluated in the first-line treatment.

CLINICAL TRIAL NUMBER

NCT02542514.

Radiotherapy or Autologous Stem-Cell Transplantation for Primary CNS Lymphoma in Patients 60 Years of Age and Younger: Results of the Intergroup ANOCEF-GOELAMS Randomized Phase II PRECIS Study

PURPOSE

To determine the efficacy and toxicity of chemoimmunotherapy followed by either whole-brain radiotherapy (WBRT) or intensive chemotherapy and autologous stem-cell transplantation (ASCT) as a first-line treatment of primary CNS lymphoma (PCNSL).

PATIENTS AND METHODS

Immunocompetent patients (18 to 60 years of age) with untreated PCNSL were randomly assigned to receive WBRT or ASCT as consolidation treatment after induction chemotherapy consisting of two cycles of R-MBVP (rituximab 375 mg/m2 day (D) 1, methotrexate 3 g/m2 D1; D15, VP16 100 mg/m2 D2, BCNU 100 mg/m2 D3, prednisone 60 mg/kg/d D1-D5) followed by two cycles of R-AraC (rituximab 375 mg/m2 D1, cytarabine 3 g/m2 D1 to D2). Intensive chemotherapy consisted of thiotepa (250 mg/m2/d D9; D8; D7), busulfan (8 mg/kg D6 through D4), and cyclophosphamide (60 mg/kg/d D3; D2). WBRT delivered 40 Gy (2 Gy/fraction). The primary end point was 2-year progression-free survival. Cognitive outcome was the main secondary end point. Analysis was intention to treat in a noncomparative phase II trial.

RESULTS

Between October 2008 and February 2014, 140 patients were recruited from 23 French centers. Both WBRT and ASCT met the predetermined threshold (among the first 38 patients in each group, at least 24 patients were alive and disease free at 2 years). The 2-year progression-free survival rates were 63% (95% CI, 49% to 81%) and 87% (95% CI, 77% to 98%) in the WBRT and ASCT arms, respectively. Toxicity deaths were recorded in one and five patients after WBRT and ASCT, respectively. Cognitive impairment was observed after WBRT, whereas cognitive functions were preserved or improved after ASCT.

CONCLUSION

WBRT and ASCT are effective consolidation treatments for patients with PCNSL who are 60 years of age and younger. The efficacy end points tended to favor the ASCT arm. The specific risk of each procedure should be considered.

Lenalidomide in combination with intravenous rituximab (REVRI) in relapsed/refractory primary CNS lymphoma or primary intraocular lymphoma: a multicenter prospective 'proof of concept' phase II study of the French Oculo-Cerebral lymphoma (LOC) Network and the Lymphoma Study Association (LYSA)†

BACKGROUND

Primary central nervous system lymphomas (PCNSLs) are mainly diffuse large B-cell lymphomas (DLBCLs) of the non-germinal center B-cell (non-GCB) subtype. This study aimed to determine the efficacy of rituximab plus lenalidomide (R2) in DLBCL-PCNSL.

PATIENTS AND METHODS

Patients with refractory/relapsed (R/R) DLBCL-PCNSL or primary vitreoretinal lymphoma (PVRL) were included in this prospective phase II study. The induction treatment consisted of eight 28-day cycles of R2 (rituximab 375/m2 i.v. D1; lenalidomide 20 mg/day, D1-21 for cycle 1; and 25 mg/day, D1-21 for the subsequent cycles); in responding patients, the induction treatment was followed by a maintenance phase comprising 12 28-day cycles of lenalidomide alone (10 mg/day, D1-21). The primary end point was the overall response rate (ORR) at the end of induction (P0 = 10%; P1 = 30%).

RESULTS

Fifty patients were included. Forty-five patients (PCNSL, N = 34; PVRL, N = 11) were assessable for response. The ORR at the end of induction was 35.6% (95% CI 21.9-51.2) in assessable patients and 32.0% (95% CI 21.9-51.2) in the intent-to-treat analysis, including 13 complete responses (CR)/unconfirmed CR (uCR; 29%) and 3 partial responses (PR; 7%). The best responses were 18 CR/uCR (40%) and 12 PR (27%) during the induction phase. The maintenance phase was started and completed by 18 and 5 patients, respectively. With a median follow-up of 19.2 months (range 1.5-31), the median progression-free survival (PFS) and overall survival (OS) were 7.8 months (95% CI 3.9-11.3) and 17.7 months (95% CI 12.9 to not reached), respectively. No unexpected toxicity was observed. The peripheral baseline CD4/CD8 ratio impacted PFS [median PFS = 9.5 months (95% CI, 8.1-14.8] for CD4/CD8 ≥ 1.6; median PFS = 2.8 months, [95% CI, 1.1-7.8) for CD4/CD8 < 1.6, P = 0.03).

CONCLUSIONS

The R2 regimen showed significant activity in R/R PCNSL and PVRL patients. These results support assessments of the efficacy of R2 combined with methotrexate-based chemotherapy as a first-line treatment of PCNSL.

CLINICAL TRIALS NUMBER

NCT01956695.

Safety and Feasibility of Repeated and Transient Blood-Brain Barrier Disruption by Pulsed Ultrasound in Patients with Recurrent Glioblastoma

PURPOSE

The blood-brain barrier (BBB) limits the efficacy of drug therapies for glioblastoma (GBM). Preclinical data indicate that low-intensity pulsed ultrasound (LIPU) can transiently disrupt the BBB and increase intracerebral drug concentrations.

PATIENTS AND METHODS

A first-in-man, single-arm, single-center trial (NCT02253212) was initiated to investigate the transient disruption of the BBB in patients with recurrent GBM. Patients were implanted with a 1-MHz, 11.5-mm diameter cranial ultrasound device (SonoCloud-1, CarThera). The device was activated monthly to transiently disrupt the BBB before intravenous carboplatin chemotherapy.

RESULTS

Between 2014 and 2016, 21 patients were registered for the study and implanted with the SonoCloud-1; 19 patients received at least one sonication. In 65 ultrasound sessions, BBB disruption was visible on T1w MRI for 52 sonications. Treatment-related adverse events observed were transient and manageable: a transient edema at H1 and at D15. No carboplatin-related neurotoxicity was observed. Patients with no or poor BBB disruption (n = 8) visible on MRI had a median progression-free survival (PFS) of 2.73 months, and a median overall survival (OS) of 8.64 months. Patients with clear BBB disruption (n = 11) had a median PFS of 4.11 months, and a median OS of 12.94 months.

CONCLUSIONS

SonoCloud-1 treatments were well tolerated and may increase the effectiveness of systemic drug therapies, such as carboplatin, in the brain without inducing neurotoxicity.See related commentary by Sonabend and Stupp, p. 3750.

Pretreatment Hemoglobin as an Independent Prognostic Factor in Primary Central Nervous System Lymphomas

BACKGROUND

Primary central nervous system lymphoma (PCNSL) is a rare subtype of extranodal lymphoma. Despite established clinical prognostic scoring such as that of the Memorial Sloan Kettering Cancer Center (MSKCC) and the International Extranodal Lymphoma Study Group, outcome prediction needs to be improved. Several studies have indicated an association between changes in hematologic laboratory parameters with patient outcomes in PCNSL. We sought to assess the association between hematological parameters and overall survival (OS) in patients with PCNSL.

METHODS

Pretreatment blood tests were analyzed in patients with newly diagnosed PCNSL (n = 182), and we divided the analysis into two cohorts (A and B, both n = 91). OS was evaluated using the Cox proportional hazards models and log-rank test. Furthermore, the accuracy of the different multivariate models was assessed by Harrell's concordance index (C-index).

RESULTS

Using prechemotherapy blood tests, anemia was found in 38 patients (41.8%) in cohort A and 34 patients (37.4%) in cohort B. In univariate analysis, anemia (<12 g/dL in women and <13 g/dL in men) was significantly associated with OS. None of the other blood tests parameters (neutrophils, lymphocyte, or platelets counts) or their ratios (neutrophil-to-lymphocyte ratio and neutrophil-to-platelets ratio) were associated with OS. In multivariate analysis, after adjusting by MSKCC score, anemia remained an independent prognostic factor. Interestingly, the prediction accuracy of OS using Harrell's C-index was similar using anemia or MSKCC (mean C-index, 0.6) and was increased to 0.67 when combining anemia and MSKCC.

CONCLUSION

The presence of anemia was associated with poor prognosis in both cohorts of PCNSL. Validation of these results and biologic role of hemoglobin levels in PCNSL requires further investigation.

IMPLICATIONS FOR PRACTICE

The prediction of the outcome of primary central nervous system lymphoma (PCNSL) using the most frequently used scores (i.e., Memorial Sloan Kettering Cancer Center [MSKCC] or International Extranodal Lymphoma Study Group) needs to be improved. We analyzed a large cohort of PCNSL to dissect the potential prognostic value of blood tests in this rare entity. We found anemia as an independent predictor for overall survival in PCNSL. Interestingly, the accuracy to predict PCNSL outcome was improved using hemoglobin level. This improvement was additional to the currently used clinical score (i.e., MSKCC). Finally, none of the other blood tests parameters or their ratios had a prognostic impact in this study.

Identification of novel recurrent ETV6-IgH fusions in primary central nervous system lymphoma

Background

Primary central nervous system lymphoma (PCNSL) represents a particular entity within non-Hodgkin lymphomas and is associated with poor outcome. The present study addresses the potential clinical relevance of chimeric transcripts in PCNSL discovered by using RNA sequencing (RNA-seq).

Methods

Seventy-two immunocompetent and newly diagnosed PCNSL cases were included in the present study. Among them, 6 were analyzed by RNA-seq to detect new potential fusion transcripts. We confirmed the results in the remaining 66 PCNSL. The gene fusion was validated by fluorescence in situ hybridization (FISH) using formalin-fixed paraffin-embedded (FFPE) samples. We assessed the biological and clinical impact of one new gene fusion.

Results

We identified a novel recurrent gene fusion, E26 transformation-specific translocation variant 6-immunoglobulin heavy chain (ETV6-IgH). Overall, ETV6-IgH was found in 13 out of 72 PCNSL (18%). No fusion conserved an intact functional domain of ETV6, and ETV6 was significantly underexpressed at gene level, suggesting an ETV6 haploinsufficiency mechanism. The presence of the gene fusion was also validated by FISH in FFPE samples. Finally, PCNSL samples harboring ETV6-IgH showed a better prognosis in multivariate analysis, P = 0.03, hazard ratio = 0.33, 95% CI = 0.12-0.88. The overall survival at 5 years was 69% for PCNSL harboring ETV6-IgH versus 29% for samples without this gene fusion.

Conclusions

ETV6-IgH is a new potential surrogate marker of PCNSL with favorable prognosis with ETV6 haploinsufficiency as a possible mechanism. The potential clinical impact of ETV6-IgH should be validated in larger prospective studies.

Prognostic value of early 18F-FDG PET scanning evaluation in immunocompetent primary CNS lymphoma patients

Primary central nervous system lymphoma (PCNSL) is a rare topographic variant of diffuse large B-cell lymphoma (DLBCL). While prognostic scales are useful in clinical trials, no dynamic prognostic marker is available in this disease. We report here the prognostic value of early metabolic response by 18F-FDG PET scanner (PET) in 25 newly diagnosed immunocompetent PCNSL patients. Induction treatment consisted of four cycles of Rituximab, Methotrexate and Temozolamide (RMT). Based on patient's general condition, consolidation by high-dose Etoposide and Aracytine was given to responding patients. Brain MRI and PET were performed at diagnosis, after two and four cycles of RMT, and after treatment completion. Two-year progression-free (PFS) and overall survival (OS) were 62% and 74%, respectively for the whole cohort. Best responses after RMT induction were 18 (72%) complete response (CR)/CR undetermined (CRu), 4 (16%) partial response, 1 (4%) progressive disease and 2 (8%) stable disease. Response evaluation was concordant between MRI and PET at the end of induction therapy. Nineteen patients (76%) had a negative PET2. Predictive positive and negative values of PET2 on end-of-treatment (ETR) CR were 66.67% and 94.74%, respectively. We observed a significant association between PET2 negativity and ETR (p = 0.001) and longer PFS (p = 0.02), while having no impact on OS (p = 0.32). Two years PFS was 72% and 33% for PET2- and PET2+ patients, respectively (p < 0.02). PET2 evaluation may help to early define a subgroup of CR PCNSL patients with a favorable outcome.

Optic Nerve Infiltration in Primary Central Nervous System Lymphoma

Importance

Visual impairment in primary central nervous system lymphoma (PCNSL) is caused mostly by intraocular lymphomatous involvement (vitritis and retinal infiltration), whereas optic nerve infiltration (ONI) is a rare condition.

Objective

To describe the clinical presentation of ONI, its imaging characteristics, and outcome.

Design, Setting and Participants

A total of 752 patients diagnosed with PCNSL were retrospectively identified from the databases of 3 French hospitals from January 1, 1998, through December 31, 2014. Of these, 7 patients had documented ONI. Exclusion criteria were intraocular involvement, orbital lymphoma, or other systemic lymphoma. Clinical presentation, neuroimaging, biological features, treatment, and outcomes were assessed.

Main Outcomes and Measures

Treatment response was evaluated clinically and radiologically on follow-up magnetic resonance imaging (MRI) according to the International PCNSL Collaborative Group response criteria.

Results

The 7 patients included 5 women and 2 men. Median age at diagnosis was 65 years (range, 49-78 years). Two patients had initial ONI at diagnosis, and 5 had ONI at relapse. Clinical presentation was marked by rapidly progressive and severe visual impairment for all patients. The MRI findings showed optic nerve enlargement in 3 patients and contrast enhancement of the optic nerve in all patients. Additional CNS lesions were seen in 4 patients. Examination of cerebrospinal fluid samples detected lymphomatous meningitis in 2 patients. Clinical outcome was poor and marked by partial recovery for 2 patients and persistent severe low visual acuity or blindness for 5 patients. Median progression-free survival after optic nerve infiltration was 11 months (95% CI, 9-13 months), and median overall survival was 18 months (95% CI, 9-27 months).

Conclusions and Relevance

Optic nerve infiltration is an atypical and challenging presentation of PCNSL. Its visual and systemic prognosis is particularly poor compared with vitreoretinal lymphomas even in response to chemotherapy. Although intraocular involvement is frequent in PCNSL and clinically marked by slowly progressive visual deterioration, lymphomatous ONI is rare and characterized by rapidly progressive severe visual impairment.