Proton craniospinal irradiation with bevacizumab and pembrolizumab for leptomeningeal disease: a case report

Early experience with proton craniospinal irradiation in adult patients with leptomeningeal disease

BACKGROUND

Leptomeningeal disease (LMD) is a fatal complication of cancer linked to poor survival rates and limited treatment options. While photon involved-field radiotherapy is the standard of care for local palliation and symptom alleviation, it lacks durable disease control. Recent data suggest proton craniospinal irradiation (pCSI) to be a promising treatment option, potentially prolonging progression-free survival (PFS) and overall survival (OS). Herein, we report our initial experience with pCSI for treating LMD from solid malignancies.

METHODS

Adult patients treated with pCSI for LMD were identified, with analysis of patient, tumor, and treatment characteristics as well as clinical outcomes.

RESULTS

Nine patients were eligible for analysis who were treated between February 2023 and February 2024. The median age at pCSI and Karnofsky performance status (KPS) were 58.6 years and 80%, respectively. The primary disease was breast cancer in 33.3%, and LMD involved both the brain and spine in 55.5%. Approximately half of the patients (55.5%) had a cerebrospinal fluid diversion before treatment, and nearly all patients underwent pCSI with 30 Gy (relative biological effectiveness) in 10 fractions. All patients completed pCSI as planned. The median clinical and central nervous system (CNS) radiographic follow-up periods were both 3.5 months. Six deaths were observed during the available follow-up. The median PFS, CNS PFS, and OS were 2.7, 4.0, and 4.0 months, respectively. Younger age, higher KPS, and concurrent treatment with targeted therapy were associated with longer OS, while cases with LMD involving both the brain and spine had shorter survival. The observed toxicity was manageable, without any occurrence of grade 4 or 5 toxicity.

CONCLUSION

pCSI can be an effective and safe treatment option for a highly selected population of patients with LMD. Further data and prospective studies are warranted to clarify its role in the management of LMD.

Proton Craniospinal Irradiation for Patients with Solid Tumor Leptomeningeal Disease: Real-World Feasibility, Toxicity, and Outcome Analysis

Leptomeningeal disease (LMD) is a devastating clinical scenario in patients with metastatic cancer [...].

Leptomeningeal Disease: Current Approaches and Future Directions

PURPOSE OF REVIEW

Leptomeningeal disease (LMD), or spread of cancer cells into the pia and arachnoid membranes encasing the brain and spinal cord, is associated with high symptom burden and poor survival at 2 to 5 months. Conventional treatments including photon-based radiation therapy, systemic chemotherapy, and intrathecal chemotherapy demonstrate limited efficacy. Despite significant successes for a range of solid tumors, immunotherapy has not yet demonstrated significant efficacy in management of LMD. Advances in understanding of LMD pathophysiology, improved diagnostics, and novel therapeutics are shifting this paradigm. In this article, we review diagnostic and treatment challenges associated with LMD.

RECENT FINDINGS

We discuss the use of novel cerebrospinal fluid (CSF) analysis techniques such as circulating tumor cell and CSF cell-free DNA assessment to overcome limitations of conventional diagnostic modalities. We then review advances in treatment including clinical trial data demonstrating efficacy of proton craniospinal radiation to treat the entire neuroaxis. We discuss emerging data regarding targeted therapeutics conferring durable survival benefit. Novel therapeutics and combinatorial treatment approaches will likely further improve outcomes for patients with LMD.

Immunotherapy for leptomeningeal disease from solid tumors: current clinical outcomes and future opportunities

Leptomeningeal disease is a debilitating, late-stage form of metastatic cancer disseminated within the cerebrospinal fluid, subarachnoid space, and leptomeninges, leading to significant neurological morbidity and mortality. As systemic cancer treatments improve, rates of leptomeningeal disease have increased, yet prognosis remains exceedingly poor. A wide range of treatment modalities have been trialed; however, no standard of care has been established. Additionally, many clinical trials exclude patients with leptomeningeal disease, limiting available prospective data. In this review, we discuss the efficacy of immunotherapy for leptomeningeal disease from solid tumors including systemic and intrathecal therapies, as well as combined therapy regimens. Our review indicates a continued deficiency in the current prospective literature and highlights ongoing research regarding the leptomeningeal immune microenvironment, which will be critical in directing future study of leptomeningeal disease treatment. Currently, the efficacy of immunotherapies on leptomeningeal disease appears limited, and further prospective research is needed to draw significant conclusions. However, recent advancement in understanding the leptomeningeal microenvironment points to potential efficacy of novel immunotherapies targeting the innate immune system, and further study is warranted to evaluate the efficacy of these treatments in this subpopulation of patients.

Proton Craniospinal Irradiation with Immunotherapy in Two Patients with Leptomeningeal Disease from Melanoma

Introduction

Proton craniospinal irradiation (pCSI) is a treatment option for leptomeningeal disease (LMD), which permits whole neuroaxis treatment while minimizing toxicity. Despite this, patients inevitably experience progression. Adding systemic therapy to pCSI may improve outcomes.

Methods

In this single-institution retrospective case series, we present the feasibility of treatment with pCSI (30Gy, 10 fractions) and an immune checkpoint inhibitor (ICI) in two sequential patients with LMD from melanoma.

Results

The first patient developed LMD related to BRAF V600E-mutant melanoma after prior ICI and BRAF-targeted therapy. After pCSI with concurrent nivolumab, the addition of relatlimab, and BRAF-targeted therapy, he remained alive 7 months after LMD diagnosis despite central nervous system progression. The second patient developed LMD related to BRAF-wildtype melanoma after up-front ICI. He received pCSI with concurrent ipilimumab and nivolumab, then nivolumab maintenance. Though therapy was held for ICI hepatitis, the patient remained progression-free 5 months after LMD diagnosis.

Conclusion

Adding an ICI to pCSI is feasible for patients with LMD and demonstrates a tolerable toxicity profile. While prospective evaluation is ultimately warranted, pCSI with ICI may confer survival benefits, even after prior ICI.