Primary CNS lymphoma and HLA class I and II alleles in a German cohort of immunocompetent patients

Targeting the tumor microenvironment in primary central nervous system lymphoma: Implications for prognosis

Primary central nervous system lymphoma (PCNSL) is a rare extranodal non-Hodgkin lymphoma, and there is limited research on its tumor microenvironment (TME). Nevertheless, more and more studies have evidence that TME has essential effects on tumor cell proliferation, immune escape, and drug resistance. Thus, it is critical to elucidate the role of TME in PCNSL. The understanding of the PCNSL TME is gradually unfolding, including factors that distinguish it from systemic diffuse large B-cell lymphoma (DLBCL). The TME in PCNSL exhibits both transcriptional and spatial intratumor heterogeneity. Cellular interactions between tumor cells and stroma cells reveal immune evasion signaling. The comparative analysis between PCNSL and DLBCL suggests that PCNSL is more likely to be an immunologically deficient tumor. In PCNSL, T cell exhaustion and downregulation of macrophage immune function are accompanied by suppressive microenvironmental factors such as M2 polarized macrophages, endothelin B receptor, HLA depletion, PD-L1, and TIM-3. MMP-9, Integrin-β1, and ICAM-1/LFA-1 play crucial roles in transendothelial migration towards the CNS, while CXCL13/CXCR5, CD44, MAG, and IL-8 are essential for brain parenchymal invasion. Further, macrophages, YKL-40, CD31, CD105, PD-1/PD-L1 axis, osteopontin, galectin-3, aggregative perivascular tumor cells, and HLA deletion may contribute to poor outcomes in patients with PCNSL. This article reviews the effect of various components of TME on the progression and prognosis of PCNSL patients to identify novel therapeutic targets.

Advances in Pathobiology of Primary Central Nervous System Lymphoma

Objective:

Primary central nervous system lymphoma (PCNSL) is a specific type of non-Hodgkin lymphoma with poor prognosis. The rare incidence of this disease and difficulty to obtain sufficient tissue material impede deep research into PCNSL. However, application of modern molecular techniques makes it possible to find biological characteristics exclusive to PCNSL. Therefore, we systematically reviewed the latest research progress on biological characteristics and pathogenesis of PCNSL.

Data Sources:

The data analyzed in this review were from the articles listed in PubMed database.

Study Selection:

Articles focusing on the biology of PCNSL at the cytogenetic or molecular level were reviewed, including clinical, basic research, and review articles.

Results:

With respect to histopathology, perivascular growth pattern and reactive perivascular T-cell infiltration are regarded as typical histopathological manifestations of tumor cells in PCNSL. Moreover, tumor cells of PCNSL predominantly express an activated B-cell-like phenotype, including CD10⁻ BCL-6⁺ MUM1⁺, CD10⁻ BCL-6⁻ MUM1⁺, and CD10⁻ BCL-6⁻ MUM1⁻. On the molecular level, some molecular and genetic alterations may contribute to malignant transformation, including mutations of proto-oncogenes and tumor suppressor genes, gains and losses of genetic material, as well as aberrant activation of some important signaling pathways, such as nuclear factor-κB and JAK/STAT pathway.

Conclusions:

The integrated molecular mechanisms involved in pathogenesis of PCNSL are not well understood. The important biomarkers indicating prognosis are not identified. Multicenter studies should be carried out to elucidate pathogenesis of PCNSL to find novel and effective therapeutic strategies.

High-dose methotrexate with or without whole brain radiotherapy for primary CNS lymphoma (G-PCNSL-SG-1): a phase 3, randomised, non-inferiority trial

BACKGROUND

High-dose methotrexate is the standard of care for patients with newly diagnosed primary CNS lymphoma. The role of whole brain radiotherapy is controversial because delayed neurotoxicity limits its acceptance as a standard of care. We aimed to investigate whether first-line chemotherapy based on high-dose methotrexate was non-inferior to the same chemotherapy regimen followed by whole brain radiotherapy for overall survival.

METHODS

Immunocompetent patients with newly diagnosed primary CNS lymphoma were enrolled from 75 centres and treated between May, 2000, and May, 2009. Patients were allocated by computer-generated block randomisation to receive first-line chemotherapy based on high-dose methotrexate with or without subsequent whole brain radiotherapy, with stratification by age (<60 vs ≥60 years) and institution (Berlin vs Tübingen vs all other sites). The biostatistics centre assigned patients to treatment groups and informed local centres by fax; physicians and patients were not masked to treatment group after assignment. Patients enrolled between May, 2000, and August, 2006, received high-dose methotrexate (4 g/m(2)) on day 1 of six 14-day cycles; thereafter, patients received high-dose methotrexate plus ifosfamide (1·5 g/m(2)) on days 3-5 of six 14-day cycles. In those assigned to receive first-line chemotherapy followed by radiotherapy, whole brain radiotherapy was given to a total dose of 45 Gy, in 30 fractions of 1·5 Gy given daily on weekdays. Patients allocated to first-line chemotherapy without whole brain radiotherapy who had not achieved complete response were given high-dose cytarabine. The primary endpoint was overall survival, and analysis was per protocol. Our hypothesis was that the omission of whole brain radiotherapy does not compromise overall survival, with a non-inferiority margin of 0·9. This trial is registered with ClinicalTrials.gov, number NCT00153530.

FINDINGS

551 patients (median age 63 years, IQR 55-69) were enrolled and randomised, of whom 318 were treated per protocol. In the per-protocol population, median overall survival was 32·4 months (95% CI 25·8-39·0) in patients receiving whole brain radiotherapy (n=154), and 37·1 months (27·5-46·7) in those not receiving whole brain radiotherapy (n=164), hazard ratio 1·06 (95% CI 0·80-1·40; p=0·71). Thus our primary hypothesis was not proven. Median progression-free survival was 18·3 months (95% CI 11·6-25·0) in patients receiving whole brain radiotherapy, and 11·9 months (7·3-16·5; p=0·14) in those not receiving whole brain radiotherapy. Treatment-related neurotoxicity in patients with sustained complete response was more common in patients receiving whole brain radiotherapy (22/45, 49% by clinical assessment; 35/49, 71% by neuroradiology) than in those who did not (9/34, 26%; 16/35, 46%).

INTERPRETATION

No significant difference in overall survival was recorded when whole brain radiotherapy was omitted from first-line chemotherapy in patients with newly diagnosed primary CNS lymphoma, but our primary hypothesis was not proven. The progression-free survival benefit afforded by whole brain radiotherapy has to be weighed against the increased risk of neurotoxicity in long-term survivors.

Genetic variants of folate and methionine metabolism and PCNSL incidence in a German patient population

Functional genetic polymorphisms involved in folate and methionine metabolism play an important role in both DNA synthesis and methylation, and affect the risk of various malignancies including lymphoproliferative disorders such as systemic non-Hodgkin's lymphoma. In a retrospective analysis of 185 immunocompetent patients with primary central nervous system lymphoma (PCNSL) and 212 population controls we therefore investigated eight genetic polymorphisms affecting methionine metabolism for potential association with the development of PCNSL. We observed underrepresentation of the G-allele of the methyltetrahydrofolate homocysteine S-methyltransferase (MTR) c.2756A > G (D919G) missense polymorphism among PCNSL patients (P = 0.045; odds ratio (OR) = 0.65; 0.43-0.99). Furthermore, for the methylenetetrahydrofolate reductase (MTHFR) c.1298A > C (E429A) polymorphism the mutated C-allele was found more frequently among PCNSL patients than among population controls (P = 0.026; OR = 1.57; 1.05-2.34). There were no associations of the other polymorphisms investigated (MTHFR c.677C > T, transcobalamin 2 (Tc2) c.776C > G, cystathionin beta-synthase (CBS) c.844_855ins68, reduced folate carrier-1 (RFC-1) c.80G > A, thymidylate synthase (TYMS) 28-bp repeat, and dihydrofolate reductase (DHFR) c.594 + 59del19 bp) and the presence of PCNSL. This analysis is the largest to date to evaluate associations between genetic variants of folate and methionine metabolism and PCNSL. Our results suggest the hypothesis that folate and methionine metabolism is relevant to susceptibility to PCNSL.