Relapsed Primary Central Nervous System Lymphoma: Current Advances

Bruton's tyrosine kinase (BTK) inhibitors for the treatment of primary central nervous system lymphoma (PCNSL): current progress and latest advances

The incidence of primary central nervous system lymphoma (PCNSL) has steadily increased, particularly in elderly patients. Although highly responsive to first-line chemotherapy and radiotherapy, approximately 50% of patients relapse or become refractory within 1 year. Prognosis following relapse is dismal and no standard salvage therapy exists. Bruton's tyrosine kinase (BTK), a key regulator of the B-cell receptor (BCR) pathway, has emerged as a promising therapeutic target. The first BTK inhibitor ibrutinib has been evaluated in the relapsed/refractory PCNSL setting, with overall response rates of 51.9%-89.0% and median progression-free survival of 4.6-4.8 months. However, ibrutinib inhibits several kinases in addition to BTK, leading to off-target effects. Second-generation BTK inhibitors have since been developed, which afford greater selectivity for BTK and fewer off-target effects. We review current practices in the diagnosis and evaluation of PCNSL, as well as clinical trials of BTK inhibitors in PCNSL and future developments in PCNSL treatment.

Targets and treatments in primary CNS lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare and highly aggressive lymphoma entirely localized in the central nervous system or vitreoretinal space. PCNSL generally initially responds to methotrexate-containing chemotherapy regimens, but progressive or relapsing disease is common, and the prognosis is poor for relapsed or refractory (R/R) patients. PCNSL is often characterized by activation of nuclear factor kappa B (NF-κB) due to mutations in the B-cell receptor (BCR) or toll-like receptor (TLR) pathways, as well as immune evasion. Targeted treatments that inhibit key PCNSL mechanisms and pathways are being evaluated; inhibition of Bruton's tyrosine kinase (BTK) downstream of BCR activation has demonstrated promising results in treating R/R disease. This review will summarize the evidence and potential for targeted therapeutic agents to improve treatment outcomes in PCNSL. This includes immunotherapeutic and immunomodulatory approaches and inhibitors of the key pathways driving PCNSL, such as aberrant BCR and TLR signaling.

Prognosis, Risk Factors, and Clinical Features of Intraocular Recurrence in Primary Vitreoretinal Lymphoma

PURPOSE

To investigate the clinical features, risk factors, and prognosis of the intraocular recurrence in primary vitreoretinal lymphoma (PVRL).

DESIGN

Retrospective case-control study.

PARTICIPANTS

Ninety-seven eyes of 51 patients diagnosed with PVRL between December 2011 and January 2021 were enrolled in this study. Fourteen patients among them had experienced intraocular recurrence.

METHODS

Data on demographic and ophthalmic characteristics, results of diagnostic tests, treatments, and prognosis of intraocular recurrence and nonrecurrence for PVRL patients were collected and compared. Multivariate logistic regression was used to identify independent risk factors. Receiver operating characteristic curves were used to determine the cutoff values.

MAIN OUTCOME MEASURES

Clinical features and risk factors.

RESULTS

Fourteen (19 eyes) of 51 PVRL patients had intraocular recurrences, resulting in a recurrence rate of 27.5% over a mean follow-up period of 42.5 months. No difference was observed in central nervous system lymphoma (CNSL) relapse rate (54.3% vs. 64.3%, P = 0.52) or median time to CNSL (36.5 months; 95% confidence interval [CI], 24.6-48.3 vs. 37.3 months; 95% CI, 24.8-49.8; P = 0.78) between intraocular nonrecurrence and intraocular recurrence groups. Furthermore, there were no statistically significant differences in the survival outcomes, such as mortality (28.6% vs. 29.7%, P = 1.00) and median overall survival (70.8 months; 95% CI, 54.0-87.7 vs. 59.2 months; 95% CI, 44.8-73.6; P = 0.30), between these 2 groups. Younger onset age (odds ratio [OR] 0.90; 95% CI, 0.84-0.98; P = 0.010), isolated PVRL (OR, 35.3; 95% CI, 2.08-600.0; P = 0.014), and no history of intravitreal chemotherapy (OR, 7.72; 95% CI, 1.37-43.6; P = 0.021) were identified as independent risk factors for intraocular recurrences. Of the patients with intraocular recurrence, 23.6% were asymptomatic and were diagnosed during routine follow-up. The rate of interleukin-10 (IL-10)/interleukin-6 > 1 was significantly lower than that at diagnosis (43.8% vs. 92.3%, P = 0.008). However, the rate of IL-10 ≥ 50 pg/mL was high (81.3%) and not significantly different from that at diagnosis (92.3%, P = 0.61).

CONCLUSIONS

This study did not identify an impact of intraocular recurrence on CNS manifestations or survival outcomes in patients with PVRL. Younger patients have a higher risk of intraocular recurrence, and combined systemic and intravitreal chemotherapy may reduce intraocular recurrence. Regular ophthalmic follow-up and IL-10 testing are recommended to detect intraocular recurrence.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Molecular Analysis of Liquid Vitreous Biopsy Reveals Occult Lymphoma Following Cytology-Negative Biopsies of the Brain and Vitreous

PURPOSE

Primary central nervous system lymphoma (PCNSL) is a rare but deadly malignancy that principally affects adults in the fifth and sixth decades of life. Despite diagnostic advances in analyses of cerebral spinal fluid and neuroimaging, definitive diagnosis of PCNSL requires primary brain tissue biopsy. While small neurosurgical biopsy volumes are pursued to minimize removal of normal brain tissue, the spatial margins to precisely biopsy pathologic tissue are narrow and can result in missed diagnoses. Furthermore, prior steroid treatment can significantly reduce tumor burden increasing the likelihood of a non-diagnostic biopsy.

METHODS

A retrospective case report from a tertiary referral center using a combination of neuroradiological studies, sterotactic tissue biopsy, and molecular testing for genome mutations.

RESULTS

A 72-year-old woman with strong suspicion for PCNSL clinically and radiologically, but cerebral spinal fluid and primary brain tissue biopsy were negative for tumor. However, vitreous liquid biopsy molecular testing for a MYD88 mutation as well as B-cell clonality (IGH/IGK rearrangement) were positive, indicating the presence of secondary vitreoretinal lymphoma from PCNSL. Only after autopsy of her brain was histopathological and immunohistochemical evidence of PCNSL confirmed.

CONCLUSION

This case illustrates the unique contribution of liquid biopsy neuropathology-oriented molecular testing in a challenging case with high clinical suspicion of PCNSL in which gold-standard diagnostic testing failed to yield a diagnosis.

Checkpoint inhibition in hematologic malignancies

Checkpoint inhibitor therapy has emerged as an effective therapeutic strategy for many types of malignancies, especially in solid tumors. Within the last two decades, numerous monoclonal antibody drugs targeting the CTLA-4 and PD-1/PD-L1 checkpoint pathways have seen FDA approval. Within hematologic malignancies, Hodgkin Lymphoma has seen the greatest clinical benefits thus far with more recent data showing efficacy in the front-line setting. As our understanding of checkpoint inhibition expands, using these pathways as a therapeutic target has shown some utility in the treatment of other hematologic malignancies as well, primarily in the relapsed/refractory settings. Checkpoint inhibition also appears to have a role as a synergistic agent to augment clinical responses to other forms of therapy such as hematopoietic stem cell transplant. Moreover, alternative checkpoint molecules that bypass the well-studied CTLA-4 and PD-1/PD-L1 pathways have emerged as exciting new therapeutic targets. Most excitingly is the use of anti-CD47 blockade in the treatment of high risk MDS and TP-53 mutated AML. Overall, there has been tremendous progress in understanding the benefits of checkpoint inhibition in hematologic malignancies, but further studies are needed in all areas to best utilize these agents. This is a review of the most recent developments and progress in Immune Checkpoint Inhibition in Hematologic Malignancies in the last decade.

Evaluation of progression-free survival as a surrogate end point in primary CNS lymphoma: a systematic review and meta-analysis

Purpose: To evaluate progression-free survival (PFS) as early surrogate endpoints for overall survival (OS) in primary CNS lymphoma (PCNSL). Methods: PubMed, Embase and Cochrane Central Library were searched up to 7 June 2022. Trial-level analyses were performed by weighted linear regression of logarithmic hazard ratios for PFS and OS. Treatment arm-level analyses were performed between PFS rates and 3- or 5-year OS rates. Results: 1471 PCNSL patients in nine randomized control trials were included. PFS was associated with OS (r = 0.750; 95% CI: 0.228-0.937). Strong linear correlations existed between 1-, 2- and 3-year PFS and 3-year OS (r = 0.896-0.928), moderate or weak correlations existed between 3- to 6-month PFS and 3-year OS, 3-month to 5-year PFS and 5-year OS. Conclusion: Short-term PFS can validly substitute for long-term OS in PCNSL.

Primary central nervous system lymphoma (PCNSL) in older patients

INTRODUCTION

Primary central nervous system lymphoma (PCNSL) is a rare, chemo and radio-sensitive tumor limited to the central nervous system. The incidence of PCSNL increases notably in the elderly population which represented approximately half of the patients. The limit of 'elderly' population remained debated and nonuniform, including 60 years as a cutoff for brain radiotherapy, 65 years for autologous stem-cell transplantation, and 70 years for the last clinical trials. Current therapeutic options include first line treatment based on high-dose methotrexate based polychemotherapy, consolidation chemotherapy, and adapted autologous stem cell transplantation for highly selected patients. At relapse, single agent targeted therapies or salvage chemotherapy followed by intensive consolidation are promising therapeutic options. Nevertheless, improving management of elderly patients is an urgent medical need that currently remains unresolved.

OBJECTIVE

We will focus on elderly patients with PCNSL and their specificities including clinical presentations, available therapeutic options and adaptations to be made.

CONCLUSION

To improve survival, it will be necessary to personalized and adapt the treatments, to each patient and his comorbidities, to increase their effectiveness and limit their toxicity in this frail population. Finally, inclusion of these patients in clinical trials is one of the major challenges to significantly change PCNSL elderly patient prognosis.

Pretreatment diffusion-weighted imaging for prediction of relapsed and refractory primary central nervous system lymphoma

Objectives

A subset of primary central nervous system lymphoma (PCNSL) has been shown to undergo an early relapsed/refractory (R/R) period after first-line chemotherapy. This study investigated the pretreatment clinical and MRI features to predict R/R in PCNSL, emphasizing the apparent diffusion coefficient (ADC) values in diffusion-weighted imaging (DWI).

Methods

This retrospective study investigated the pretreatment MRI features for predicting R/R in PCNSL. Only patients who had undergone complete preoperative and postoperative MRI follow-up studies were included. From January 2006 to December 2021, 52 patients from two medical institutions with a diagnosis of PCNSL were included (median follow-up time, 26.3 months). Among these, 24 (46.2%) had developed R/R (median time to relapse, 13 months). Cox proportional hazard regression analyses were performed to determine hazard ratios for all parameters.

Results

Significant predictors of R/R in PCNSL were female sex, complete response (CR) to first-line chemotherapy, and ADC value/ratio (p < 0.05). Cut-off points of ADC values and ADC ratios for prediction of R/R were 0.68 × 10-3 mm2/s and 0.97, with AUCs of 0.78 and 0.77, respectively (p < 0.05). Multivariate Cox proportional hazards analysis showed that failure of CR to first-line chemotherapy and low ADC values (<0.68 × 10-3 mm2/s) were significant risk factors for R/R, with hazard ratios of 5.22 and 14.45, respectively (p < 0.05). Kaplan-Meier analysis showed that lower ADC values and ratios predicted significantly shorter progression-free survival (p < 0.05).

Conclusion

Pretreatment ADC values in DWI offer quantitative valuable information for the treatment planning in PCNSL.

The Current Landscape of Immune Checkpoint Inhibitor Immunotherapy for Primary and Metastatic Brain Tumors

Antibodies against immune checkpoint inhibitors (ICIs) have revolutionized the treatment of multiple aggressive malignancies, including melanoma and non-small cell lung cancer. ICIs for the treatment of primary and metastatic brain tumors have been used with varying degrees of success. Here, we discuss the available evidence for the use of ICIs in the treatment of primary and metastatic brain tumors, highlighting challenges and opportunities for furthering this type of cancer immunotherapy in neuro-oncology.

European Association of Neuro-Oncology (EANO) guidelines for treatment of primary central nervous system lymphoma (PCNSL)

The management of primary central nervous system (PCNSL) is one of the most controversial topics in neuro-oncology because of the complexity of the disease and the limited number of controlled studies available. In 2021, given recent advances and the publication of practice-changing randomized trials, the European Association of Neuro-Oncology (EANO) created a multidisciplinary task force to update the previously published evidence-based guidelines for immunocompetent adult patients with PCNSL and added a section on immunosuppressed patients. The guideline provides consensus considerations and recommendations for the treatment of PCNSL, including intraocular manifestations and specific management of the elderly. The main changes from the previous guideline include strengthened evidence for the consolidation with ASCT in first-line treatment, prospectively assessed chemotherapy combinations for both young and elderly patients, clarification of the role of rituximab even though the data remain inconclusive, of the role of new agents, and the incorporation of immunosuppressed patients and primary ocular lymphoma. The guideline should aid the clinicians in everyday practice and decision making and serve as a basis for future research in the field.

Use of rituximab, temozolomide, and radiation in recurrent and refractory primary central nervous system lymphoma in the Philippines: a retrospective analysis

Background

Refractory disease in primary central nervous system lymphoma (PCNSL) may occur despite adequate initial treatment. There is currently no standard of care for relapsed and recurrent PCSNL. No study to date documents using a combined regimen of radiotherapy, temozolomide, and rituximab. This study aimed to present the clinical course and outcomes of patients with recurrent or refractory disease who were given a combination of radiation, temozolomide, and rituximab.

Methods

Retrospective analysis was employed to evaluate data from recurrent or refractory PCNSL patients who were treated with radiation, temozolomide, and rituximab in two tertiary hospitals in the Philippines. Baseline demographics, treatment regimen, and outcomes were analyzed.

Results

Fifteen patients with a median age of 56 years were included, 11 with refractory disease and 4 with recurrent disease. Patients with bulky disease received either whole brain radiotherapy or partial field radiotherapy with rituximab and temozolomide given during radiation and for 6 months after radiation. Overall response rate to salvage therapy was 93.3% (14/15). Median overall survival from initial diagnosis was not reached (median follow-up: 84 months). Mortality rate was 33.3% (5/15), but only 2 out of 5 mortalities were from disease progression. There were only two reported cases of mild allergic reactions to rituximab, which did not result in treatment interruption.

Conclusion

Rituximab, temozolomide, and radiotherapy can be considered as an effective and safe salvage therapy for relapsed and recurrent central nervous system lymphoma.

Cutaneous metastasis of primary diffuse large B-cell lymphoma of the central nervous system developing 4 years after complete remission: Diagnosis confirmed by comparison of clones

B-cell lymphoma of the central nervous system (CNS) is a rare malignancy with diffuse large B-cell lymphoma (DLBCL) variant being most common. Although DLBCL has a high propensity to relapse locally within the CNS, only a few cases of cutaneous metastasis have been described in the literature. We present a unique case of cutaneous metastasis of a primary DLBCL of the CNS in a 79-year-old man who was in clinical remission for 4 years until presenting with a lesion in the left adrenal gland and cutaneous nodules on the left flank. Skin biopsy specimen revealed a diffuse dermal infiltrate of atypical B-cell lymphocytes with expression of CD20, BCL-2, BCL-6, and MUM-1, suggestive of DLBCL. For differentiation between another primary or a recurrent process, immunoglobulin kappa (IgK) light chain gene rearrangement was performed and demonstrated that the DLBCL of the skin and CNS were of the same clonal origin. Restaging computerized tomography after initiating chemotherapy and daily ibrutinib showed complete resolution of the left adrenal mass and resolving cutaneous lesions. Our case demonstrates the rare, late cutaneous metastasis of DLBCL of the CNS and highlights the importance of genetic testing for the distinction between the primary and secondary lesions.