Primary central nervous system lymphoma: recent progress, many remaining questions

High-dose methotrexate with or without rituximab in newly diagnosed primary CNS lymphoma

OBJECTIVE

To evaluate the efficacy of rituximab (R) when added to high-dose methotrexate (HD-MTX) in patients with newly diagnosed immunocompetent primary CNS lymphomas (PCNSLs).

METHODS

Immunocompetent adults with newly diagnosed PCNSL treated at The Johns Hopkins Hospital between 1995 and 2012 were investigated. From 1995 to 2008, patients received HD-MTX monotherapy (8 g/m2 initially every 2 weeks and after complete response [CR] monthly to complete 12 months of therapy). From 2008 to 2012, patients received the same HD-MTX with rituximab (375 mg/m2) with each HD-MTX treatment. CR rates and median overall and progression-free survival were analyzed for each patient cohort in this single-institution, retrospective study.

RESULTS

A total of 81 patients were identified: 54 received HD-MTX (median age 66 years) while 27 received HD-MTX/R (median age 65 years). CR rates were 36% in the HD-MTX cohort and 73% in the HD-MTX/R cohort (p = 0.0145). Median progression-free survival was 4.5 months in the HD-MTX cohort and 26.7 months in the HD-MTX/R cohort (p = 0.003). Median overall survival was 16.3 months in the HD-MTX cohort and has not yet been reached in the HD-MTX/R cohort (p = 0.01).

CONCLUSIONS

The addition of rituximab to HD-MTX appears to improve CR rates as well as overall and progression-free survival in patients with newly diagnosed PCNSL. Comparisons of long-term survival in the 2 cohorts await further maturation of the data.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that in immunocompetent patients with PCNSL, HD-MTX plus rituximab compared with HD-MTX alone improves CR and overall survival rates.

Limited detection of IgH gene rearrangements in plasma of patients with primary central nervous system lymphoma

Chemotherapy-based treatment of patients with primary central nervous system lymphoma can lead to durable remissions and potentially cure in a fraction of patients. Accurate assessment of residual disease is necessary to determine the duration and success of treatment that cannot be achieved by contrast-enhanced imaging due to limited sensitivity and specificity. A tumor-derived blood-based biomarker, if detectable and quantifiable, could serve as a more specific and reliable marker for these patients. The goal of this study was to assess whether lymphoma-specific IgH rearrangements can be detected in plasma of patients with PCNSL. PCNSL tissue was analyzed by capturing and sequencing the IgH genomic regions (IgCap) using next generation sequencing with the Illumina platform. Plasma of patients with detected IgH rearrangement was then analyzed for presence of the respective rearrangement using polymerase chain reaction. Tumor tissue and matched plasma of five treatment-naïve patients with biopsy-proven PCNSL (mean age of 65.6 years; range 62-68 years) were analyzed. All patients had measurable contrast-enhancing disease on MRI at time of plasma collection. IgH rearrangements were identified in 4 of 5 analyzed PCNSL tissue samples. The respective rearrangement could be detected in the plasma of 1 patient (25 %) but not in the others. IgH rearrangements can be detected in tumor tissue of patients with PCNSL using IgCap, however, they are absent or only present in minimal quantities in plasma, even in treatment-natïve patients with bulky disease. Alternative strategies to develop circulating biomarkers for PCNSL patients need to be explored.

Imaging and therapy with rituximab anti-CD20 immunotherapy in an animal model of central nervous system lymphoma

PURPOSE

To evaluate the effect of rituximab monoclonal antibody (mAb) on MRI tumor volumetrics and efficacy in a rat model of central nervous system (CNS) lymphoma when delivery to the brain was optimized with osmotic blood-brain barrier disruption (BBBD).

EXPERIMENTAL DESIGN

Female nude rats with intracerebral MC116 human B-cell lymphoma xenografts underwent baseline MRI and were randomized into 5 groups (n = 6 per group): (i) BBBD saline control; (ii) methotrexate with BBBD; (iii) rituximab with BBBD; (iv) rituximab and methotrexate with BBBD; and (v) intravenous rituximab. Tumor volumes were assessed by MRI at 1 week, and rats were followed for survival.

RESULTS

BBBD increased delivery of yttrium-90-radiolabeled mAb in the model of CNS lymphoma. Control rats showed 201 ± 102% increase in tumor volume on MRI 1 week after entering the study and median 14-day survival (range: 6-33). Tumor growth on MRI was slowed in the methotrexate treatment group, but survival time (median: 7 days; range: 5-12) was not different from controls. Among 17 evaluable rats treated with rituximab, 10 showed decreased tumor volume on MRI. All rituximab groups had increased survival compared with control, with a combined median of 43 days (range: 20-60, P < 0.001). There were no differences by route of delivery or combination with methotrexate.

CONCLUSIONS

Rituximab was effective at decreasing tumor volume and improving survival in a model of CNS lymphoma and was not affected by combination with methotrexate or by BBBD. We suggest that rituximab warrants further study in human primary CNS lymphoma.

Ocular relapse of primary brain lymphoma in immunocompetent patient, treated with intrathecal rituximab

Primary brain lymphoma is a rare variant of extranodal non-Hodgkin's B-cell lymphoma. In >90% of cases, this is diffuse large B-cell lymphoma with CD20 expression and is confined to the brain, meninges, spinal cord, and eyes. It accounts for fewer than 7% of primary brain tumors. Its incidence has been rising in recent years in immunocompetent patients in their fifth and sixth decades. The rate of relapse after initial therapy based on high-dose methotrexate and/or total brain irradiation is high. There is no consensus for treating relapse, which ranges from retreatment with high doses of methotrexate, polychemotherapy, high doses of chemotherapy backed up by autologous stem-cell transplant to intrathecal chemotherapy, with widely differing results. Given the lack of consensus and poor results, new therapy options have appeared, including immunotherapy with rituximab. At a systemic level, alongside chemotherapy, its results are very modest and limited due to the low concentration it reaches in cerebrospinal fluid (CSF). However, its intrathecal and intraventricular use, though only isolated cases have been reported, has provided promising results.