Central Nervous System Lymphoma Research Articles

Detection of circulating tumor DNA in plasma of patients with primary CNS lymphoma by digital droplet PCR

BackgroundPrimary central nervous system lymphoma (PCNSL) are rare mature B-cell lymphoproliferative diseases characterized by a high incidence of MYD88 L265P and CD79B Y196 hotspot mutations. Diagnosis of PCNSL can be challenging. The aim of the study was to analyze the detection rate of the MYD88 L265P and CD79B Y196 mutation in cell free DNA (cfDNA) in plasma of patients with PCNSL.MethodsWe analyzed by digital droplet PCR (ddPCR) to determine presence of the MYD88 L265P and CD79B Y196 hotspot mutations in cfDNA isolated from plasma of 24 PCNSL patients with active disease. Corresponding tumor samples were available for 14 cases. Based on the false positive rate observed in 8 healthy control samples, a stringent cut-off for the MYD88 L265P and CD79B Y196 mutation were set at 0.3% and 0.5%, respectively.ResultsMYD88 L265P and CD79B Y196 mutations were detected in 9/14 (64%) and 2/13 (15%) tumor biopsies, respectively. In cfDNA samples, the MYD88 L265P mutation was detected in 3/24 (12.5%), while the CD79B Y196 mutation was not detected in any of the 23 tested cfDNA samples. Overall, MYD88 L265P and/or CD79B Y196 were detected in cfDNA in 3/24 cases (12.5%). The detection rate of the combined analysis did not improve the single detection rate for either MYD88 L265P or CD79B Y196.ConclusionThe low detection rate of MYD88 L265P and CD79B Y196 mutations in cfDNA in the plasma of PCNSL patients argues against its use in routine diagnostics. However, detection of MYD88 L265P by ddPCR in cfDNA in the plasma could be considered in challenging cases.

Machine learning-based pathomics signature of histology slides as a novel prognostic indicator in primary central nervous system lymphoma

PurposeTo develop and validate a pathomics signature for predicting the outcomes of Primary Central Nervous System Lymphoma (PCNSL).MethodsIn this study, 132 whole-slide images (WSIs) of 114 patients with PCNSL were enrolled. Quantitative features of hematoxylin and eosin (H&E) stained slides were extracted using CellProfiler. A pathomics signature was established and validated. Cox regression analysis, receiver operating characteristic (ROC) curves, Calibration, decision curve analysis (DCA), and net reclassification improvement (NRI) were performed to assess the significance and performance.ResultsIn total, 802 features were extracted using a fully automated pipeline. Six machine-learning classifiers demonstrated high accuracy in distinguishing malignant neoplasms. The pathomics signature remained a significant factor of overall survival (OS) and progression-free survival (PFS) in the training cohort (OS: HR 7.423, p < 0.001; PFS: HR 2.143, p = 0.022) and independent validation cohort (OS: HR 4.204, p = 0.017; PFS: HR 3.243, p = 0.005). A significantly lower response rate to initial treatment was found in high Path-score group (19/35, 54.29%) as compared to patients in the low Path-score group (16/70, 22.86%; p < 0.001). The DCA and NRI analyses confirmed that the nomogram showed incremental performance compared with existing models. The ROC curve demonstrated a relatively sensitive and specific profile for the nomogram (1-, 2-, and 3-year AUC = 0.862, 0.932, and 0.927, respectively).ConclusionAs a novel, non-invasive, and convenient approach, the newly developed pathomics signature is a powerful predictor of OS and PFS in PCNSL and might be a potential predictive indicator for therapeutic response.

Non-Hodgkin’s Lymphoma of the Central Nervous System with N-Methyl-D-Aspartate Receptor Antibody Positivity - A Case Report

Purpose: Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, among the paraneoplastic syndromes, is a recently characterized autoimmune encephalitis most commonly associated with antibodies against subunits of the NMDAR in the central nervous system. As a paraneoplastic syndrome, anti-NMDAR encephalitis is commonly associated with ovarian teratomas, small cell lung carcinomas and testicular germ cell tumors. To our knowledge, there have been no cases with primary central nervous system lymphoma (PCNSL), a rare type of extranodal non-Hodgkin’s lymphoma, without lymph node involvement associated with anti-NMDAR encephalitis. Case Report: A 58-year-old right-handed male patient with complaints of instability in walking for two months, progressively smaller handwriting, hallucinations when falling asleep or waking up, decreased memory, inability to maintain attention was admitted to our hospital for further diagnosis and treatment. Lumbar puncture was performed with the diagnosis of possible encephalitis after many further examinations and CSF studies revealed NMDAR antibody positivity, leading to the initial diagnosis of anti - NMDAR encephalitis. He was treated with high dose methylprednisolone and intravenous immunoglobulin. Due to the continuation of the patient’s presenting symptoms and cranial magnetic resonance imaging findings, a stereotactic brain biopsy was performed from the area with contrast enhancement and the diagnosis was revised as PCNSL associated with NMDAR antibody positivity. Conclusion: This report emphasizes the importance of anti-NMDAR encephalitis as a paraneoplastic syndrome in previously undiagnosed PCNSL. Therefore, it is crucial to be aware of anti-NMDAR encephalitis as a paraneoplastic neurological syndrome that can present with non-Hodgkin’s lymphoma. It is necessary to continually observe the evolution of the disease and perform further diagnostic tests for early identification.

Recent advances in liquid biopsy of central nervous system lymphomas: case presentations and review of the literature.

Surgical biopsy is the gold standard for diagnosing central nervous system (CNS) lymphomas. However, reliable liquid biopsy methods for diagnosing CNS lymphomas have quickly developed and have been implicated in clinical decision-making. In the current report, we introduce two patients for whom liquid biopsy was essential for diagnosing CNS lymphomas and discuss the rapidly growing applications of this technology.

Abstract 1022: Integration of cerebrospinal fluid methylome and proteome can obviate the need for biopsy in central nervous system lymphoma

Abstract Background: The diagnosis of intra-axial brain tumors requires histopathological examination of tissue obtained by neurosurgery in current clinical practice, which comes with inherent risks. Some patients, particularly those with primary CNS lymphoma (PCNSL), only undergo surgery to obtain a diagnosis and do not derive any therapeutic benefit from surgical resection or debulking. Less-invasive techniques for diagnosis, such as liquid biopsy, therefore provides an opportunity to mitigate surgical risk in these patients. Methods: Patients with histopathology confirmed glioblastoma (GBM, IDH wild type), brain metastases (BM), and PCNSL with accompanying cerebrospinal fluid (CSF) samples were included in our study. Cell-free DNA methylation profiling and shotgun proteomics were obtained for all patients and used to train classifiers to distinguish each tumour entity from others. Specifically, binomial elastic net regression models were built by combining both data modalities using established early and late integration paradigms and performance was compared to classifiers built from individual data types alone. Each model was repeated 100 fold and performance assessed on an untouched testing subset. Results: Our cohort includes 20 patients with GBM, 17 with BM, and 14 with PCNSL, each with matching CSF cell-free DNA methylation and shotgun proteomic profiling. We show that these data can be integrated to fully discriminate PCNSL from its major diagnostic counterparts with a perfect median AUC of 1.00 (95% CI 1-1) and 100% specificity. Integrated "lymphoma vs other" models significantly outperform models trained on methylation or protein data alone, though the same dramatic improvement was not demonstrated in GBM or BM, suggesting synergistic biological information is specific to lymphoma. Conclusions: There is a critical need to diagnose patients with intra-axial tumours, particularly PCNSL, without relying on invasive and costly surgery. We present the most specific and accurate CNS lymphoma classifier to date by integrating the methylome and proteome of CSF. This has the potential for immediate clinical utility, eliminating the need for biopsy in an important subset of these patients. Citation Format: Alex P. Landry, Jeffrey A. Zuccato, Vikas Patil, Mathew Voisin, Justin Z. Wang, Yosef Ellenbogen, Chloe Gui, Andrew Ajisebutu, Farshad Nassiri, Gelareh Zadeh. Integration of cerebrospinal fluid methylome and proteome can obviate the need for biopsy in central nervous system lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1022.

Retracted: Effect of Tumor Microenvironment and Angiogenesis on Clinical Outcomes of Primary Central Nervous System Lymphoma.

[This retracts the article DOI: 10.1155/2021/3291762.].

How does deep learning/machine learning perform in comparison to radiologists in distinguishing glioblastomas (or grade IV astrocytomas) from primary CNS lymphomas?: a meta-analysis and systematic review

Several studies have been published comparing deep learning (DL)/machine learning (ML) to radiologists in differentiating PCNSLs from GBMs with equivocal results. We aimed to perform this meta-analysis to evaluate the diagnostic accuracy of ML/DL versus radiologists in classifying PCNSL versus GBM using MRI. The study was performed in accordance with PRISMA guidelines. Data was extracted and interpreted by two researchers with 12 and 23 years' experience, respectively, and QUADAS-2 tool was used for quality and risk-bias assessment. We constructed contingency tables to derive sensitivity, specificity accuracy, summary receiver operating characteristic (SROC) curve, and the area under the curve (AUC). Our search identified 11 studies, of which 8 satisfied our inclusion criteria and restricted the analysis in each study to reporting the model showing highest accuracy, with a total sample size of 1159 patients. The random effects model showed a pooled sensitivity of 0.89 [95% CI:0.84-0.92] for ML and 0.82 [95% CI:0.76-0.87] for radiologists. Pooled specificity was 0.88 [95% CI: 0.84-0.91] for ML and 0.90 [95% CI: 0.81-0.95] for radiologists. Pooled accuracy was 0.88 [95% CI: 0.86-0.90] for ML and 0.86 [95% CI: 0.78-0.91] for radiologists. Pooled AUC of ML was 0.94 [95% CI:0.92-0.96]and for radiologists, it was 0.90 [95% CI: 0.84-0.93]. MRI-based ML/DL techniques can complement radiologists to improve the accuracy of classifying GBMs from PCNSL, possibly reduce the need for a biopsy, and avoid any unwanted neurosurgical resection of a PCNSL.

Glofitamab stimulates immune cell infiltration of CNS tumors and induces clinical responses in secondary CNS lymphoma

AbstractAlthough CD20×CD3 bispecific antibodies are effective against systemic B-cell lymphomas, their efficacy in central nervous system (CNS) lymphoma is unknown. Here, we report the CD20×CD3 bispecific glofitamab penetrates the blood-brain barrier, stimulates immune-cell infiltration of CNS tumors, and induces clinical responses in patients with secondary CNS.

Bifunctional iRGD-Exo-DOX crosses the blood-brain barrier to target central nervous system lymphoma

Central nervous system lymphoma (CNSL) is a type of hematological tumor. Treatment of CNSL is difficult due to the existence of the blood–brain barrier (BBB). Here, we used exosomes (Exos), a type of extracellular vesicle, and iRGD to construct a new drug carrier system and use it to load doxorubicin (DOX). The results of in vitro and in vivo experiments showed that the iRGD-Exo-DOX system can efficiently and securely transport DOX through the BBB and target tumor cells. The results suggest that iRGD-Exo-DOX may cross the BBB through brain microvascular endothelial cell-mediated endocytosis. Together, our study indicates an impactful treatment of central nervous system tumors.

Histopathological Diagnosis of Primary Central Nervous System Lymphoma after Therapy with Corticosteroids or Anticoagulants.

In patients with primary central nervous system lymphoma (PCNSL), the choice of surgical strategy for histopathologic assessments is still controversial, particularly in terms of preoperative corticosteroid (CS) therapy. To provide further evidence for clinical decision-making, we retrospectively analyzed data from 148 consecutive patients who underwent surgery at our institution. Although patients treated with corticosteroids preoperatively were significantly more likely to require a second or third biopsy (p = 0.049), it was only necessary in less than 10% of the cases with preoperative (but discontinued) corticosteroid treatment. Surprisingly, diagnostic accuracy was significantly lower when patients were treated with anticoagulation or dual antiplatelet therapy (p = 0.015). Preoperative CSF sampling did not provide additional information but was associated with delayed surgery (p = 0.02). In conclusion, preoperative CS therapy can challenge the histological diagnosis of PCNSL. At the same time, our data suggest that preoperative CS treatment only presents a relative contraindication for early surgical intervention. If a definitive diagnosis cannot be made after the first surgical intervention, the timing of a repeat biopsy after the discontinuation of CS remains a case-by-case decision. The effect of anticoagulation and dual antiplatelet therapy on diagnostic accuracy might have been underestimated and should be examined closely in future investigations.

Brain tumor grading diagnosis using transfer learning based on optical coherence tomography.

In neurosurgery, accurately identifying brain tumor tissue is vital for reducing recurrence. Current imaging techniques have limitations, prompting the exploration of alternative methods. This study validated a binary hierarchical classification of brain tissues: normal tissue, primary central nervous system lymphoma (PCNSL), high-grade glioma (HGG), and low-grade glioma (LGG) using transfer learning. Tumor specimens were measured with optical coherence tomography (OCT), and a MobileNetV2 pre-trained model was employed for classification. Surgeons could optimize predictions based on experience. The model showed robust classification and promising clinical value. A dynamic t-SNE visualized its performance, offering a new approach to neurosurgical decision-making regarding brain tumors.

Survival outcomes and treatment experience of 124patients with primary central nervous system lymphoma.

Primary central nervous system lymphoma (PCNSL) is arare malignancy of the central nervous system with high invasiveness. There is little consensus on the treatment of PCNSL. This study retrospectively studied data from PCNSL patients in asingle center to summarize treatment experience and explore prognostic factors. Survival curves were drawn using the Kaplan-Meier method and prognostic factors were analyzed using Cox's hazards model. In multivariate analysis, cerebrospinal fluid lactic acid dehydrogenase (CSF LDH; p = 0.005 and p = 0.002), neutrophil to lymphocyte ratio (NLR; p = 0.014 and p = 0.038), and completion of four cycles of induction therapy (p < 0.001and p < 0.001) were significant and independent predictors of overall survival (OS) and progression-free survival (PFS), respectively. On the basis of this study, we propose that PCNSL patients should receive early induction therapy with sufficient cycles. Subsequent consolidation therapy can prevent relapses and improve survival. In patients with PCNSL, the independent prognostic factors for OS and PFS were CSF LDH level, NLR, and full cycles of induction therapy.

Factors related to central nervous system involvement of primary vitreoretinal lymphoma.

This single center retrospective study aimed to investigate the factors associated with central nervous system (CNS) involvement of primary vitreoretinal lymphoma (PVRL). Clinical features of patients with PVRL (Group 1), those diagnosed with vitreoretinal lymphoma (VRL) after primary CNS lymphoma diagnosis (Group 2), and those concurrently diagnosed with CNS lymphoma and VRL (Group 3), were compared. The main outcomes included sex, age, types of treatment, survival, visual acuity, diagnostic methods, VRL recurrence, ocular manifestations, and interleukin levels in the aqueous humor. Groups 1, 2, and 3 included 66 eyes in 38 patients, 29 eyes in 18 patients, and 14 eyes in 8 patients, respectively. Group 3 had shorter overall survival (OS) than Groups 1 and 2 (P = 0.042 and P = 0.009, respectively). The three groups did not differ in progression-free survival (P = 0.060). The 5-year survival rates of Groups 1, 2, and 3 were 56.5%, 44.0%, and 25.0%, respectively (P = 0.001). Patients with CNS involvement in Group 1 exhibited VRL recurrence (P < 0.001), high interleukin-10 (P = 0.024), and sub-retinal pigment epithelium (RPE) infiltration (P = 0.009). Patients experiencing VRL recurrence in Group 1 tended to show CNS involvement (P < 0.001). Patients concurrently diagnosed with CNS lymphoma and VRL had a shorter OS and a lower 5-year survival rate. In patients with PVRL, the recurrence of VRL, high interleukin-10, and sub-RPE infiltration were associated with CNS involvement.

Stereotactic Radiosurgery and Highly Active Antiretroviral Therapy for HIV-Related Primary Central Nervous System Lymphomas: A Prospective Study Analyzing the Efficacy and Safety

BACKGROUND AND OBJECTIVES: Stereotactic radiosurgery (SRS) has been well established and considered a safe alternative for primary central nervous system lymphomas (PCNSLs). However, in HIV-related PCNSL, the use of SRS remains controversial. The purpose of this study was to evaluate the efficacy and safety of SRS in HIV-related PCNSL. METHODS: Forty-two adult patients with confirmed PCNSL and no previous radiotherapy or chemotherapy were selected, with 16 receiving Gamma Knife Radiosurgery (GKRS) alone and 26 receiving Highly Active Antiretroviral Therapy (HAART) before GKRS. Follow-up evaluations were conducted at 3, 6, 12, and 24 months post-treatment using clinical and imaging techniques. Statistical analyses were performed using SPSS v22, assessing for new lesions, changes in lesion size, progression-free survival, and overall survival. RESULTS: HAART/GKRS showed a significantly higher rate of complete response compared with the GKRS group, with 53.8% vs 18.8% (P = .048). The mean progression-free survival for the HAART/GKRS group and the GKRS group was 39.7 months and 31.2 months, respectively (P = .0051). Patients with a delayed HAART initiation (&gt;6 months) exhibited an increased burden of T2 white matter lesions and a higher number of large lesions (odds ratio = 1.9, 95% CI = 1.44-2.42, P = .001). However, no significant difference was observed between the two groups regarding radionecrosis. CONCLUSION: The study highlights the potential benefits of adding HAART to GKRS for patients with PCNSL, leading to improved survival outcomes. An early initiation of HAART was associated with less tumor progression, underscoring the importance of timely administration of HAART in patients with AIDS-related PCNSL.

Clinical profile of central nervous system space-occupying lesions and their association with CD4 counts in patients with HIV: A prospective observational study.

Neurological manifestations are one of the major concerns for patients with human immunodeficiency virus (HIV). The secondary spectrum includes space-occupying lesions (SOL), including tuberculoma, cryptococcosis, candidiasis, toxoplasmosis, primary central nervous system lymphoma (PCNSL), and progressive multifocal leukoencephalopathy (PML). To assess the neurological manifestations, disease outcome, and their associations with cluster of differentiation 4 (CD4) counts in patients with HIV. This single-center, prospective, observational study was performed in the Department of General Medicine of a tertiary care institute, over a period of 2 years (January 2017 to December 2018). The study included 150 known or newly diagnosed HIV patients with CNS SOL. The physical examination, laboratory investigations, and imaging were conducted on every patient, and the findings were noted. The patients mainly presented with hemiparesis (52%), had involvement of the frontal region (38.7%), and were diagnosed with tuberculoma (29.3%). Other diagnoses were toxoplasmosis (22.7%), PML (17.3%), PCNSL (15.3%), brain abscess (10%), and neurocysticercosis (5.3%). Of 150 patients, 136 (90.7%) were survivors, while 14 (9.3%) were non-survivors. The mean CD4 count was significantly less in patients with toxoplasmosis (P < 0.0001) and PCNSL (P = 0.02), and significantly higher in patients with tuberculoma (P < 0.0001) and brain abscess (P = 0.0009) relative to other causes of SOL. Moreover, the mean CD4 count was not significantly associated with survivors and non-survivors (P = 0.28). In patients with HIV, CD4 count was significantly low in toxoplasmosis and PCNSL, and high in tuberculoma and brain abscess.

Consensus guidelines for the management of primary central nervous system lymphoma for low and middle-income countries.

Primary lymphoma of the central nervous system (PCNSL) is a rare and aggressive form of extranodal non-Hodgkin lymphoma primarily involving the brain, spinal cord, cerebrospinal fluid, and eyes. The role of surgical intervention in PCNSL is currently limited to biopsy and decompression of critical structures if needed - extended resection is debated. Chemotherapy is the mainstay of treatment. In lower and middle-income countries (LMICs), issues like delayed diagnosis and resource constraints are widespread. These guidelines provide a framework for addressing PCNSL in LMICs, emphasizing the importance of early diagnosis, tailored treatment approaches, and ongoing patient monitoring to improve outcomes for this rare and aggressive disease.

Zanubrutinib plus Cytarabine in Patients with Refractory/Relapsed Primary Central Nervous System Lymphoma

Introduction: Primary central nervous system lymphoma (PCNSL) is a rare subtype of aggressive extranodal non-Hodgkin lymphoma. Currently, there is no standard of care for the treatment of refractory or relapsed PCNSL (r/r PCNSL). We conducted a prospective single-arm phase II study to evaluate zanubrutinib plus cytarabine for r/r PCNSL. Methods: Using Simon’s two-stage design, we analyzed 34 patients who received high-dose cytarabine (3.0 g/m2 once daily) for 2 days and zanubrutinib (160 mg twice daily) for 21 days each cycle for up to 6 cycles. The study was registered at www.chictr.org.cn as #ChiCTR2000039229. Results: The median follow-up was 19 months. The overall response rate was 64.7% (95% confidence interval [CI], 47.9–78.5%) with a complete remission or unconfirmed complete remission rate of 47.1% (16/34) and a partial remission rate of 17.6% (6/34). The median progression-free survival was 4.5 months (95% CI, 1.5–9.4), and the median OS was 18 months (95% CI, 9.5 to not estimable). The median duration of the response was 9 months (95% CI, 3.2 to not estimable). The most common treatment-emergent adverse events were thrombocytopenia (55.9%). No treatment-related death occurred. Conclusion: Zanubrutinib and cytarabine showed efficacy in r/r PCNSL with an acceptable safety profile.

Efficacy and Safety of BTKis in Central Nervous System Lymphoma: A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis aimed to evaluate the efficacy and safety of Bruton tyrosine kinase inhibitors (BTKis) for central nervous system lymphoma (CNSL). A systematic review was carried out to identify relevant studies from the PubMed, Embase, Cochrane Library, Web of Science, WanFang, CNKI, and CBM databases. The studies included patients with CNSL who received BTKis and reported the overall response (OR), complete remission (CR), and partial response (PR). An overall effect analysis was performed using STATA 15.0. A random-effects model was utilized to calculate the pooled rates, and 95% confidence intervals (CI) were determined for all outcomes. A total of 21 studies involving 368 patients were included in the meta-analysis. For newly diagnosed CNSL, due to the small simple size, we conducted a quantitative description, and the ORR could reach up to 100%. For relapsed/refractory patients, the pooled ORR was 72% (95% CI: 64-80%, I2 = 54.89%, p = 0.00), with a pooled CR and PR of 43% (95% CI: 33-54%, I2 = 65.40%, p = 0.00) and 23% (95% CI: 13-35%, I2 = 78.05%, p = 0.00), respectively. Most adverse events were hematology-related and generally manageable. BTKis showed acceptable efficacy and safety in treating patients with CNSL. However, large and well-designed trials are still required to confirm BTKis as a treatment for CNSL.

Impact of Prophylactic Trimethoprim-Sulfamethoxazole on Clearance of High-Dose Methotrexate in Adult Patients.

High-dose methotrexate (HDMTX) is an antineoplastic dosing strategy used to treat various cancers including primary central nervous system lymphoma. Trimethoprim-sulfamethoxazole (TMP/SMX) is commonly used for antibiotic prophylaxis against Pneumocystis pneumonia infections in this patient population. Significant drug-drug interactions between TMP/SMX and methotrexate (MTX) leading to adverse outcomes have been documented, primarily in adult patients taking MTX for rheumatologic conditions. This study is a single-center, retrospective, cohort study comparing outcomes in patients where TMP/SMX was held during HDMTX and patients who received concurrent prophylactic TMP/SMX during treatment. The primary end point was mean MTX level at 24, 48, and 72 hours. Secondary end points included rate of nonhematologic toxicity, rate of hematologic toxicity, median days to MTX clearance, and frequency of glucarpidase utilization. In total, 248 cycles of HDMTX were analyzed from 221 individual patients. One hundred ninety-one cycles were administered without prophylactic TMP/SMX, and 57 were administered with TMP/SMX. The median MTX level at 24, 48, and 72 hours in those without versus with prophylactic TMP/SMX was 4.30 versus 4.30, 0.29 versus 0.30, and 0.14 versus 0.15, respectively. Similarly, rates of hematologic and nonhematologic toxicities did not differ significantly between groups with the exception of neutropenia; however, there was no corresponding increased rate of neutropenic fever. Only one patient received glucarpidase and had not received TMP/SMX. Prophylactic TMP/SMX had minimal interaction with HDMTX and does not lead to increased time to clearance or clinically relevant toxicities. Prophylactic TMP/SMX can be safely administered with HDMTX in adult patients.

Interim FDG-PET improves treatment failure prediction in primary central nervous system lymphoma: An LOC network prospective multicentric study.

The purpose of our study was to assess the predictive and prognostic role of 2-18F-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/MRI during high-dose methotrexate-based chemotherapy (HD-MBC) in de novo primary central nervous system lymphoma (PCNSL) patients aged 60 and above. This prospective multicentric ancillary study included 65 immunocompetent patients who received induction HD-MBC as part of the BLOCAGE01 phase III trial. FDG-PET/MRI were acquired at baseline, post 2 cycles (PET/MRI2), and posttreatment (PET/MRI3). FDG-PET response was dichotomized with "positive" indicating persistent tumor uptake higher than the contralateral mirroring brain region. Performances of FDG-PET and International PCNSL Collaborative Group criteria in predicting induction response, progression-free survival (PFS), and overall survival (OS) were compared. Of the 48 PET2 scans performed, 9 were positive and aligned with a partial response (PR) on MRI2. Among these, 8 (89%) progressed by the end of the induction phase. In contrast, 35/39 (90%) of PET2-negative patients achieved complete response (CR). Among the 18 discordant responses at interim (PETCR/MRIPR), 83% ultimately achieved CR. Eighty-seven percent of the PET2-negative patients were disease free at 6 months versus 11% of the PET2-positive patients (P < .001). The MRI2 response did not significantly differentiate patients based on their PFS, regardless of whether they were in CR or PR. Both PET2 and MRI2 independently predicted OS in multivariate analysis, with PET2 showing a stronger association. Our study highlights the potential of interim FDG-PET for early management of PCNSL patients. Response-driven treatment based on PET2 may guide future clinical trials. LOCALYZE, NCT03582254, ancillary of phase III clinical trial BLOCAGE01, NCT02313389 (Registered July 10, 2018-retrospectively registered) https://clinicaltrials.gov/ct2/show/NCT03582254?term=LOCALYZE&draw=2&rank=1.