PURPOSE: Clinical outcomes of patients with CNS lymphomas (CNSLs) are remarkably heterogeneous, yet identification of patients at high risk for treatment failure is challenging. Furthermore, CNSL diagnosis often remains unconfirmed because of contraindications for invasive stereotactic biopsies. Therefore, improved biomarkers are needed to better stratify patients into risk groups, predict treatment response, and noninvasively identify CNSL. PATIENTS AND METHODS: We explored the value of circulating tumor DNA (ctDNA) for early outcome prediction, measurable residual disease monitoring, and surgery-free CNSL identification by applying ultrasensitive targeted next-generation sequencing to a total of 306 tumor, plasma, and CSF specimens from 136 patients with brain cancers, including 92 patients with CNSL. RESULTS: Before therapy, ctDNA was detectable in 78% of plasma and 100% of CSF samples. Patients with positive ctDNA in pretreatment plasma had significantly shorter progression-free survival (PFS, P < .0001, log-rank test) and overall survival (OS, P = .0001, log-rank test). In multivariate analyses including established clinical and radiographic risk factors, pretreatment plasma ctDNA concentrations were independently prognostic of clinical outcomes (PFS HR, 1.4; 95% CI, 1.0 to 1.9; P = .03; OS HR, 1.6; 95% CI, 1.1 to 2.2; P = .006). Moreover, measurable residual disease detection by plasma ctDNA monitoring during treatment identified patients with particularly poor prognosis following curative-intent immunochemotherapy (PFS, P = .0002; OS, P = .004, log-rank test). Finally, we developed a proof-of-principle machine learning approach for biopsy-free CNSL identification from ctDNA, showing sensitivities of 59% (CSF) and 25% (plasma) with high positive predictive value. CONCLUSION: We demonstrate robust and ultrasensitive detection of ctDNA at various disease milestones in CNSL. Our findings highlight the role of ctDNA as a noninvasive biomarker and its potential value for personalized risk stratification and treatment guidance in patients with CNSL. [Media: see text]

Noninvasive disease monitoring and risk stratification by circulating tumor DNA (ctDNA) profiling has become a potential novel strategy for patient management in B-cell lymphoma. Emerging innovative therapeutic options and an unprecedented growth in our understanding of biological and molecular factors underlying lymphoma heterogeneity have fundamentally increased the need for precision-based tools facilitating personalized and accurate disease profiling and quantification. By capturing the entire mutational landscape of tumors, ctDNA assessment has some decisive advantages over conventional tissue biopsies, which usually target only one single tumor site. Due to its non- or minimal-invasive nature, serial and repeated ctDNA profiling provides a real-time picture of the genetic composition and facilitates quantification of tumor burden any time during the course of the disease. In this review, we present a comprehensive overview of technologies used for ctDNA detection and genotyping in B-cell lymphoma, focusing on pre-analytical and technical requirements, the advantages and limitations of various approaches, and highlight recent advances around improving sensitivity and suppressing technical errors. We broadly review potential applications of ctDNA in clinical practice and for translational research by describing how ctDNA might enhance lymphoma subtype classification, treatment response assessment, outcome prediction, and monitoring of measurable residual disease. We finally discuss how ctDNA could be implemented in prospective clinical trials as a novel surrogate endpoint and be utilized as a decision-making tool to guide lymphoma treatment in the future.

Various clinical scenarios preclude or delay invasive stereotactic biopsies and subsequent histopathological assessment for the diagnosis of central nervous system lymphoma (CNSL), necessitating innovative minimal-invasive strategies. We designed a digital droplet PCR (ddPCR) assay for minimal-invasive identification of CNSL in clinical practice by detecting MYD88 L265P mutations in circulating tumor DNA (ctDNA) of cerebrospinal fluid (CSF). After assay approval by the national accreditation authority, this laboratory-developed test (LDT) was first independently validated in a cohort of 128 patients with confirmed malignant or inflammatory/infectious brain diseases, revealing a sensitivity of 67% and specificity of 100% for correct CNSL diagnosis. Following implementation in a clinical laboratory environment, the LDT was applied to 205 CSF samples from 182 independent patients, reporting results to treating physicians with a median turnaround time of 5 days. The MYD88 L265P mutation was detected in 33% of CSF specimens, obviating the need for invasive surgical biopsies in 37% of patients and guiding lymphoma-specific treatment in 48% of evaluable cases. 94% of patients undergoing CNS-directed treatment based on CSF-ctDNA profiling objectively responded to therapies. Collectively, our results demonstrate that minimal-invasive identification of CNSL by ctDNA genotyping in CSF can effectively guide clinical management and has practice-changing impact for a substantial subset of patients with unknown CNS lesions.

Background/Objectives: Short induction followed by high-dose chemotherapy and autologous stem cell transplantation (HCT-ASCT) is effective in newly diagnosed elderly patients with primary central nervous system lymphoma (PCNSL) but associated with significant toxicity. Geriatric assessments (GAs) may help to predict treatment risk and prognosis, yet no standardized GAs exist for PCNSL. Our aim was to evaluate the impact of GA on HCT-ASCT eligibility and survival. Methods: We analyzed 65 patients > 65 years treated in the MARiTA and MARTA studies. Treatment comprised 2 cycles of rituximab, HD-MTX and cytarabine followed by HCT-ASCT. GAs at diagnosis were analyzed for progression-free survival (PFS), overall survival (OS) and premature end of treatment (pEOT). Results: After median follow-up of 43 months, 12-month PFS/OS were 69.2% (95% CI 56.5–78.9%)/70.8% (58.1–80.2%) from diagnosis and 80.4% (66.6–88.9%)/84.3% (71.1–91.8%) from time of HCT-ASCT. ECOG PS ≥ 2, Lachs geriatric screening (Lachs) ≥30% and Cumulative Illness Rating Scale-Geriatric (CIRS-G) ≥6, ≥7 and ≥8, respectively, were significantly associated with pEOT in univariate analysis (UVA). In multivariate analysis (MVA), CIRS-G remained significant. A composite EBL score (ECOG PS ≥ 2, Barthel Index of Activities of Daily Living (Barthel) < 20, Lachs ≥ 30%) ≤1 predicted successful completion of HCT-ASCT in >90% of patients. ECOG PS ≥ 2 and Barthel < 20 were associated with decreased PFS and OS in UVA; ECOG PS ≥ 2 remained significant in MVA. Conclusions: This is the first study to link GA with treatment feasibility in elderly PCNSL patients undergoing intensive therapy. Our results will be validated in the PRIMA-CNS trial (EudraCT 2020-001181-10).

Background/Objectives: Relapsed and refractory (rr) primary large B-cell lymphoma of the central nervous system (PCNSL) has a dismal prognosis, and the standard of care is not established. The most common genetic imbalance includes the B-cell lymphoma 2 (BCL-2) locus. Methods: We planned a bi-centric phase Ib dose-escalation study with the chemotherapy-free combination of the BCL-2 inhibitor venetoclax and CD20 antibody obinutuzumab for rrPCNSL patients in Germany. The intended treatment consisted of 6 cycles of fixed-dose obinutuzumab at 1000 mg intravenously every 3 weeks, and an oral daily dose of 600, 800, or 1000 mg venetoclax, depending on the planned dosing group, followed by a 12-month venetoclax maintenance period. The primary endpoint was the pharmacokinetics of venetoclax and obinutuzumab in cerebrospinal fluid (CSF). Results: This study was prematurely terminated after registration of 5/15 (33%) patients in dosing group 1 (600 mg oral daily dose of venetoclax) between May 2020 and November 2021. The mean ratio of the concentration of venetoclax in CSF over peripheral blood was 0.55% (±0.28 standard deviation (SD)) and 0.25% (±0.23 SD) for obinutuzumab. Two of five patients achieved complete remission, and each one patient achieved partial remission and stable disease as best response. The median duration of response was 6.5 months (range 0.7–47). Conclusions: Venetoclax and obinutuzumab can penetrate into the central nervous system, but the CSF concentration did not correlate with the outcome. The combination is feasible, tolerable, and may lead to durable responses in selected rrPCNSL patients.