Melanoma is third most common cancer to metastasize to the leptomeningeal space and confers a dismal prognosis. We retrospectively identified 87 cases of melanoma related leptomeningeal disease (M-LMD) diagnosed between 2011-2020 at Moffitt Cancer Center. The average age at diagnosis was 54 years (range 28-93 years) with a male predominance (50 men vs 36 women). There was a significant increase in median overall survival (OS) for patients with BRAF V600E mutation, but only if they were treated with combined BRAF/MEK inhibitors after diagnosis of LMD (5.54 months vs 1.39 months; p < 0.01). Immune checkpoint inhibitors also associated with a small but significant increase in OS when given after diagnosis of M-LMD (2.73 months vs 1.38mths; p < 0.01). There was no association between OS and gender (p > 0.05). The current data supports use of BRAF/MEK inhibitors for treatment of BRAF V600E mutated M-LMD. More work is needed to improve OS for these patients and patients without a targetable mutation and M-LMD.

BACKGROUND LMD from systemic cancer has a dismal prognosis with median survivals of 8-10 weeks. A phase 2 trial of PD-1 inhibitor monotherapy in LMD showed median overall survival (OS) of 3.6 months (Brastianos P et al., 2020). We determined the safety/efficacy of avelumab, a PD-L1 inhibitor with WBRT in patients with LMD (NCT0371768). This combination can treat the tumor directly and increase BBB permeability (Li, 2003; Nordal, 2005) allowing the increased egress of activated T cells into the meninges/CSF. METHODS Patients received concurrent avelumab 800 mg IV q2 weeks for ≤ 5 cycles (unless PD or unacceptable toxicity) with WBRT 3000 cGy in 10 fractions. Primary endpoints are safety/DLTs and OS at 3 months. Secondary endpoints are CSF T-cell/cytokine profiles (scRNAseq, phosophoproteomics etc.). RESULTS A total of 15 patients (7 breast, 7 lung & 1 other) were enrolled (n = 13 F, ages 32-79). Pts receiving anti-PD-1/PD-1L/PD-L2/CD137,CTLA-4 therapy ≤ 6 months prior were excluded. Three of 15 patients had grade 3/4 AEs (diarrhea, lymphopenia, decreased WBC count in 3 patients). Seven patients (50%) were alive at 3 or 6 months. The estimated median follow up in 14 patients is 4.75 months (range, 0.92 – 30.05 months, 95% CI is 1.32 ~ 19.82). The median PFS is 3.75 months (95% CI = 0.85-15.16) and median OS is 6.89 months (95% CI = 1.18-14.7). CONCLUSIONS The combination of avelumab and WBRT is safe, well tolerated, and demonstrates encouraging activity in patients with LMD with an OS that is longer than other published series. Multiple platform interrogation of CSF (analysis underway) will determine mechanisms of LMD therapeutic/resistance effects.

Leptomeningeal disease is a devastating complication characterized by the rapid onset of debilitating neurological symptoms and a markedly poor prognosis. It is diagnosed in 5-15% of hematological cancers. Here, we aim to identify the metabolic and immune remodeling of the tumor leptomeningeal microenvironment in Non-Hodgkin lymphoma through comprehensive multi-omic analysis of patient specimens, in vivo models, and in vitro functional studies. Cerebrospinal fluid (CSF) from leptomeningeal lymphoma (LML) patients and tumor-free controls were collected and analyzed using single-cell RNA sequencing (scRNA-Seq), metabolomics, proteomics, and lipidomics. Patients’ CSF cellular components were highly enriched with heterogeneous B-cell populations. Few T-lymphocytes in LML patients showed expression of activation or proliferation markers. Poor prognosis was associated with significant infiltration of macrophages and a lack of dendritic cells. These findings were confirmed to be unique to LML using immune-competent animal models where tumor cells were injected intrathecally, and into lymph nodes. Moreover, LML patients’ CSF showed an accumulation of branched-chain keto-acids (BKAs), which are well-known neurotoxins, metabotoxins, and acidogens. Absolute quantification of individual BKAs was confirmed by high-performance liquid chromatography and showed a 30-fold increase in LML patients’ CSF. To investigate the effect of BKAs accumulation on T-lymphocytes, we examined their viability, proliferation, and activation with BKAs treatment in the context of physiological CSF. Cell trace violet-labeled T lymphocytes showed a significant reduction in proliferation and viability with increasing doses of BKAs. Additionally, a significant decline in the secretion of TNF-α, interferon-γ, granzyme B, and IL-2 was found using ELISA assays, indicating a reduction in T-lymphocyte activation. The proteomic and lipidomic analysis of patients’ CSF also revealed a significant downregulation in proteins and lipids vital for neuronal development, synaptic organization, and myelin sheath integrity. Similarly, scRNA-Seq of the leptomeningeal layer collected from the LML mouse model revealed compromised leptomeningeal integrity. Neurological scoring of the LML mouse model showed disease progression to be associated with rapid neurological decline. To investigate the direct effect of BKAs on the leptomeningeal and neuronal integrity, we tested different concentrations of BKAs on murine primary neuronal cells and human leptomeningeal cells (HMC). MTT assays showed a significant reduction in HMC metabolic activity after 72 hours and in neuronal metabolic activity after 7 days. In conclusion, our data unveil the immunosuppressive and neurodegenerative role of BKAs in the leptomeningeal tumor microenvironment. Citation Format: Mariam Lotfy Khaled, Gerald Wallace, Brittany Evernden, Zhihua Chen, Hasan Alhaddad, Yuan Ren, Oscar Ospina, Maclean Hall, Ann Chen, Timothy J. Robinson, John Koomen, Shari Pilon-thomas, Peter Forsyth, Inna Smalley. Branched-chain keto acids exert an immune-suppressive and neurodegenerative microenvironment in CNS leptomeningeal lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1192.

Background Breast cancer-related leptomeningeal disease (BC-LMD) is a dire diagnosis for 5–8% of patients with breast cancer (BC). We conducted a retrospective review of BC-LMD patients diagnosed at Moffitt Cancer Center (MCC) from 2011–2020, to determine the changing incidence of BC-LMD, which factors impact progression of BC CNS metastasis to BC-LMD, and which factors affect OS for patients with BC-LMD Methods Patients with BC and brain/spinal metastatic disease were identified. For those who eventually developed BC-LMD, we used Kaplan-Meier survival curve, log-rank test, univariable, and multivariate Cox proportional hazards regression model to identify factors affecting time from CNS metastasis to BC-LMD and OS. Results 128 cases of BC-LMD were identified. The proportion of BC-LMD to total BC patients was higher between 2016–2020 when compared to 2011–2015. Patients with HR + or HER2 + BC experienced longer times between CNS metastasis and LMD than patients with triple-negative breast cancer (TNBC). Systemic therapy and whole-brain radiation therapy (WBRT) prolonged progression to LMD in all patients. Hormone therapy in patients with HR + BC delayed BC-CNS metastasis to LMD progression. Lapatinib delayed progression to LMD in patients with HER2 + BC. Patients with TNBC-LMD had shorter OS compared to those with HR + and HER2 + BC-LMD. Systemic therapy, intrathecal (IT) therapy, and WBRT prolonged survival for all patients. Lapatinib and trastuzumab improved OS in patients with HER2 + BC-LMD. Conclusions Increasing rates of BC-LMD provide treatment challenges and opportunities for clinical trials. Trials testing lapatinib and/or similar tyrosine kinase inhibitors, IT therapies, and combination treatments are urgently needed.

Patients with primary central nervous system lymphoma (PCNSL) typically present with non-focal neurological symptoms, including disorientation, poor balance and memory loss with unifocal or multifocal periventricular lesions seen on MRI. Deviations from these characteristic findings can delay diagnosis and lead to additional diagnostic tests being needed. The present study reports a 68-year-old man with a recent varicella zoster infection and history of acetylcholine receptor antibody-positive myasthenia gravis who received mycophenolate mofetil for 22 years. He presented with left eye vision changes and cognitive memory deficits. A brain MRI showed an enhancing lesion within his left medulla extending to the cerebellum. Cerebrospinal fluid analysis was positive for Epstein-Barr virus (EBV) and negative for malignancy. He was diagnosed with varicella zoster virus vasculopathy. At 3 months later, a repeat brain MRI showed multiple new enhancing lesions developing bilaterally along the periventricular white matter. Soon after, he presented to a local ER with acute left-sided blurry vision and worsening memory loss, and he began receiving steroids. Because of rapid symptom progression, he underwent resection of the left frontal lesion, which showed EBV-induced diffuse large B-cell lymphoma (DLBCL). Mycophenolate mofetil was discontinued, and within 24 h of one dose of intravenous 500 mg/m 2 rituximab, he had a dramatic improvement in left eye vision and memory loss. He experienced mixed responses to rituximab after 3 cycles. Following one dose of high-dose methotrexate, he developed subsequent chronic kidney disease and required dialysis. He received whole-brain radiation therapy with craniospinal radiation and is currently in complete remission. An EBV-induced DLBCL diagnosis should be highly considered for patients with periventricular lesions and EBV-positive cerebrospinal fluid. Misdiagnosis or delay in PCNSL diagnosis because of atypical features in disease presentation and radiographic findings could lead to PCNSL progression and worsening neurological deficits.