Dudek, Arkadiusz Z.

With improved medical treatments, the prognosis for many malignancies has improved, and more patients are presenting for transplant evaluation with a history of treated cancer. Solid organ transplant (SOT) recipients with a prior malignancy are at higher risk of posttransplant recurrence or de novo malignancy, and they may require a cancer surveillance program that is individualized to their specific needs. There is a dearth of literature on optimal surveillance strategies specific to SOT recipients. A working group of transplant physicians and cancer-specific specialists met to provide expert opinion recommendations on optimal cancer surveillance after transplantation for patients with a history of malignancy. Surveillance strategies provided are mainly based on general population recurrence risk data, immunosuppression effects, and limited transplant-specific data and should be considered expert opinion based on current knowledge. Prospective studies of cancer-specific surveillance models in SOT recipients should be supported to inform posttransplant management of this high-risk population.

Abstract Background: The prognosis of patients with MM with CNS mets is poor. E6201 is an intravenous (IV) MEK inhibitor with activity against BRAF V600-mutated MM cell lines, including MAPK resistance alteration. A previous phase I trial demonstrated activity of E6201 in BRAF V600E mutated MM with a Maximal Tolerated Dose of 320mg/m2 given IV once a week x 3 weeks q 28 days. 2/23 (8.7%) of patients had a PR, 8/23 (34.8%) had SD. Two patients with MM and brain mets achieved near-CR which led to preclinical studies that demonstrated E6201 is unaffected by P-gp and BCRP transport and achieved higher brain to blood concentration (266%).In this trial, patients with BRAF mutation + MM with brain mets, single agent E6201 given at 320mg/m2 twice weekly x 3 weeks q 28 days was determined to be safe. One patient had CNS SD and a PR in lung mets, and a second patient achieved CNS stable disease and CR in a leg melanotic lesion. The drug was well-tolerated with one reversible AE thrombocytopenia (Gr 2). The final review showed intracranial response of SD in 2/4 (50%) patients and systemic SD in 3/4 (75%) patients. Methods: We are currently accruing to the dose escalation cohort of E6201 with dabrafenib 150 mg twice daily orally (n=up to 22 evaluable patients). E6201 is administered IV at 320mg/m2 twice weekly for 3 weeks every 28 days. Patients must have stage IV melanoma with BRAF mutation with at least one active lesion in the brain. Prior local therapy is allowed if done at least 3 weeks prior to cycle 1. Participants must be on a stable dose of steroids for at least 7 days and have an ECOG <!–=2. The study allows one prior BRAF/MEK inhibitor therapy. The primary objectives are to determine the MTD of E6201 when combined with dabrafenib and the response rate of brain mets. The secondary objectives include duration of response, extracranial response, progression free survival, overall survival, and impact of BRAF mutation subtype and safety of the combination. Clinicaltrials.gov: NCT05388877 References:1.Gampa G, et al. Brain distribution of a novel MEK inhibitor E6201: implications in the treatment of melanoma brain metastases. 2018. Drug Metab Dispos.2.Tibes R et al. Safety, pharmacokinetics, and preliminary efficacy of E6201 in patients with advanced solid tumors, including melanoma: results of a phase I study. 2018. Brit J of Cancer. 3.Babiker Gm et al, E6201, an intravenous MEK1 inhibitor, achieves an exceptional response in BRAF V600E mutated metastatic malignant melanoma with brain metastases. 2018. Inv New Drugs4.Gampa G, Kim M, Cook-Rostie N, Laramy JK, Sarkaria JN, Paradiso L, DePalatis L, Elmquist WF. Brain distribution of a novel MEK inhibitor E6201: Implications in the treatment of melanoma brain metastases. 2018. Drug Met Disp.–> Citation Format: Mahesh Seetharam, Roxana Dronca, Arkadiusz Z. Dudek, Garth Nelson, Matthew Block, Skylar Starling, Amber Baskin, Renee Bradshaw, Courtney Nelson, Kylee Andrews, Alisha Birgin, Cristina Watson, Yiyi Yan, Daruka Mahadevan, Svetomir Markovic, Tom Myers, Linda Paradiso, Hani Babiker. Phase 1 trial of MEK1 inhibitor E6201 plus dabrafenib in patients (pts) with BRAF V600-mutated metastatic melanoma (MM) with central nervous system (CNS) metastases (mets) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT157.

Abstract Objective: LX-101 is a next-generation, targeted therapy directed to the insulin-like growth factor 1 receptor (IGF-1R). LX-101 consists of a proprietary IGF-1 variant coupled to a cytotoxic methotrexate payload. LX-101 was previously evaluated in Phase 1 trials of adult patients with advanced, pretreated cancers, where it was well-tolerated and demonstrated single agent activity. Neither a dose limiting toxicity, nor a maximum tolerated dose was reached, leaving potential room for additional dose escalation and schedule optimization. Multiple aggressive cancers of unmet need have genetic alterations affecting the IGF-1R pathway and/or high IGF-1R expression that correlates with poor outcomes, including certain cancers of the breast, head and neck, Ewing’s sarcoma, osteosarcoma, and others. Prior attempts at inhibiting IGF-1R with non-payload bearing naked monoclonal antibodies or small molecules produced a range of clinical outcomes including some partial and complete responses. None of these agents, however, were ultimately approved, potentially due to suboptimal potency that allowed for escape mechanisms, including redundant signaling pathways, and the lack of enrichment for select tumor types with strong ties to the IGF-1/IGF-1R pathway. Herein, we investigated the anti-tumor activity of the payload-bearing agent LX-101 against IGF-1R-involved cancer cell lines. Methods: Cell lines were incubated with LX-101 (~1.6 - 2500nM). Cell viability was assessed by CellTiter-Glo after 4 days. IC50s were calculated using GraphPad PRISM software. Results: LX-101 displayed potency against head and neck cancer (FaDu, IC50 = 9 nM), triple negative breast cancer (BT-20, IC50 = 17 nM), Ewing’s sarcoma, including EWSR1-FLI1 gene fusion-positive cell lines RD-ES (IC50 = 10 nM), A-673 (IC50 = 14 nM), and SK-ES-1 (IC50 = 29 nM) and EWSR1-ERG gene fusion-positive cell line CADO-ES1 (IC50 = 14 nM). LX-101 was also potent against PAX3-FOXO1 gene fusion positive alveolar rhabdomyosarcoma (SJCRH30, IC50 = 23 nM), osteosarcoma (143B, IC50 = 6 nM; HOS, IC50 = 7 nM; U2OS, IC50 = 32 nM), and neuroblastoma (SK-N-AS, IC50 = 16 nM; IMR-32, IC50 = 20 nM; SH-SY5Y, IC50 = 30 nM). Conclusion: These results demonstrate that LX-101 has potent preclinical anti-tumor activity against multiple cancer cell lines with well-established ties to the IGF-1/IGF-1R pathway, including with different genetic and epigenetic alterations. These data support further clinical development of LX-101 in IGF-1R-involved cancers. New clinical trials are planned. Citation Format: Matt Hoberman, Arkadiusz Z. Dudek. LX-101, a novel, clinical stage, payload-bearing targeted therapy directed to the insulin-like growth factor receptor (IGF-1R), demonstrates potent preclinical anti-tumor activity against multiple cancer types with well-established ties to the IGF-1/IGF-1R pathway [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 1918.

Clarkson disease, or monoclonal gammopathy–associated idiopathic systemic capillary leak syndrome (ISCLS), is a rare, relapsing-remitting disorder featuring the abrupt extravasation of fluids and proteins into peripheral tissues, which in turn leads to hypotensive shock, severe hemoconcentration, and hypoalbuminemia. The specific leakage factor(s) and pathways in ISCLS are unknown, and there is no effective treatment for acute flares. Here, we characterize an autonomous vascular endothelial defect in ISCLS that was recapitulated in patient-derived endothelial cells (ECs) in culture and in a mouse model of disease. ISCLS-derived ECs were functionally hyperresponsive to permeability-inducing factors like VEGF and histamine, in part due to increased endothelial nitric oxide synthase (eNOS) activity. eNOS blockade by administration of N (γ)-nitro-l-arginine methyl ester (l-NAME) ameliorated vascular leakage in an SJL/J mouse model of ISCLS induced by histamine or VEGF challenge. eNOS mislocalization and decreased protein phosphatase 2A (PP2A) expression may contribute to eNOS hyperactivation in ISCLS-derived ECs. Our findings provide mechanistic insights into microvascular barrier dysfunction in ISCLS and highlight a potential therapeutic approach.

Abstract BACKGROUND Leptomeningeal disease (LMD) is a devastating complication of cancer with median overall survival (OS) of 3-6 months following diagnosis. Proton craniospinal irradiation (pCSI) is a novel treatment option for LMD, permitting whole neuroaxis treatment with tolerable toxicity and improved efficacy compared to conventional photon whole brain radiation therapy and as needed focal spine radiotherapy. Despite this, patients experience progression and succumb to LMD. Addition of systemic therapy to pCSI may improve outcomes. METHODS In this single institution retrospective case series, we report feasibility of combination treatment with pCSI and immune checkpoint inhibitor (ICI) in patients with LMD from solid tumors. RESULTS Three patients were treated with pCSI (30 Gy in 10 fractions) and ICI. The first patient developed LMD related to large cell neuroendocrine carcinoma of lung primary, diagnosed by imaging and cytology, having previously undergone resection and stereotactic radiosurgery for brain metastases. Clinical and radiographic improvement was noted following pCSI, bevacizumab, and pembrolizumab therapy. Patient experienced disease progression and passed away only after ICI was held due to hypophysitis, with 6-month OS. The second patient developed LMD related to BRAF V600E mutant melanoma, diagnosed by imaging and cytology, having previously undergone ICI and BRAF-targeted therapy. Following pCSI, relatlimab, nivolumab, and BRAF-targeted therapy, the patient remains alive 7 months after LMD diagnosis despite radiographic progression treated with carboplatin, paclitaxel, intrathecal IL-2, ipilimumab, and bevacizumab. The third developed LMD related to BRAF-wildtype melanoma, diagnosed by imaging, having previously received ICI. Patient underwent pCSI followed by ipilimumab and nivolumab, progression-free 5 months after LMD diagnosis. CONCLUSION Addition of systemic therapy to pCSI is feasible for patients with LMD. Combination of ICI and pCSI may confer additional survival benefit, even among patients with prior exposure to ICI. These initial promising results warrant prospective evaluation.

ABSTRACT 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.

9538 Background: Uveal melanoma has a poor prognosis following metastasis to the liver. Immune checkpoint inhibitors (ICIs) are often utilized in patients with metastatic uveal melanoma (MUM); however, ICIs in MUM have low response rates. We studied the association of immune infiltrates in MUM liver metastases with survival outcomes for all patients, in addition to evaluating if immune infiltrates improve survival for patients treated with ICIs. Methods: We included MUM patients with liver metastases who had pre-treatment liver biopsies available at Mayo Clinic Rochester. Demographics, disease characteristics, treatments, and clinical outcomes were obtained from the electronic medical record. Core biopsies of liver metastases were reviewed for the presence of lymphocytes at interface of the tumor and liver parenchyma, and for tumor-infiltrating lymphocytes (TILs). If TILs were present, then additional immunohistochemistry (IHC) staining was performed for CD3, CD4, CD8, PD1, CD25, and FoxP3. Overall survival (OS) was estimated with the Kaplan-Meier method and compared between groups with Cox proportional hazards regression. Median OS and hazard ratios (HR) were calculated and p-values (p) <0.05 were considered statistically significant. Results: 140 patients with MUM who had pre-treatment liver biopsies were identified. 122 biopsies were evaluable for the presence of lymphocytes, either at the tumor-liver interface, or for TILs. 80/122 (65.6%) biopsies showed presence of any lymphocyte and 27/80 had TILs. 27 biopsies had sufficient tissue for further IHC classification. CD8+ T cells were identified in 27/27 samples, T cell PD1 positivity ≥1% in 4/27 samples, and regulatory T cell markers (CD25 and/or FoxP3) in 18/27 samples. Median OS for the entire cohort was 16 months (mo). Patients still alive at the time of data analysis had at least one year of follow-up available (range 13-124 mo). Univariate analyses (UVA) showed no significant improvement in OS based on the presence of any lymphocytes (HR 1.01, p 0.98), lymphocytes at the tumor-liver interface (HR 1.10, p 0.64), TILs (HR 0.78, p 0.27), >50% CD8+ T cells (HR 0.88, p 0.77), or absence of FoxP3+ T cells (HR 0.68, p 0.40). In the 69 patients treated with ICIs (pembrolizumab, nivolumab, or ipilimumab plus nivolumab), neither the presence of any lymphocytes (HR 1.19, p 0.56) nor TILs (HR 0.68, p 0.24) were associated with an OS benefit. Conclusions: We present a large cohort of patients with MUM where we characterized immune infiltrates in liver metastases and evaluated clinical outcomes. OS did not significantly improve with the presence of any lymphocytes, TILs, CD8+ T cells, or with the absence of FoxP3+ T cells. These results were consistent across all patients whether they were treated with ICIs or not. Our findings suggest that lymphocytes in MUM are functionally dormant and highlights the need for novel immune-activating treatment strategies.

e18634 Background: Informed patients have better health outcomes. In a study of 1,057 patient encounters with 3,552 clinical decisions, only 9% resulted in informed medical decisions.The complexity of treatments and patients' limitations in health literacy (especially common in underserved communities) make it difficult for patients to engage in SDM. In 2017, A Breath of Hope Lung Foundation introduced An Animated Patient’s Guide to Lung Cancer (APG), an online resource aimed at improving patient knowledge. Methods: APG consists of animations, expert FAQ videos, slide shows, infographics, patient-experience videos, knowledge-assessment tools, and learner feedback. Video views, duration of use, and learner responses to multiple-choice questions on the APG website were collected for 33 months – through August 2020. Total APG views, most frequently viewed animations and expert videos were monitored on the website and on YouTube, to measure learner responses to outcome-based questions, and learner intent-to-implement changes. Results: 212,336 total views: 142,998 unique visitors: 59% from U.S. and 41% from 50 other countries. Unique U.S. visitors: 43,872 patients, 16,030 caregivers, and 7,593 health providers. 94% reported they will ‘use new information to better self-manage their lung cancer’ (n = 277); 98% ‘will discuss information learned with their doctor’ (n = 455), and 93% ‘plan to discuss treatment options with their doctor’ (n = 272). Conclusions: Multimedia ‘animated’ formats of learning tailored to the needs and learning styles of lung cancer patients provides effective learning, informed patients, increased management skills, and improved engagement in shared decision making.

9048 Background: Brain metastases continue to be the major cause of morbidity and mortality in patients with metastatic melanoma. The impact of BRAF mutations and effectiveness of BRAF inhibitors on the brain metastases in these patients is lacking. Methods: Preclinical studies were conducted to assessthe steady-state brain and plasma distribution of vemurafenib, a BRAF inhibitor in FVB wild-type and Mdr1a/b-/-Bcrp1-/- mice deficient in the drug efflux transporters, p-glycoprotein (P-gp) and breast cancer resistant protein (BCRP). A retrospective analysis of patients with metastatic melanoma treated at University of Minnesota from August 2011 to December 2012 was conducted. A similar analysis of cases treated at Mayo Clinic is underway. Results: The preclinical studies in mice show that both P-gp and BCRP play a significant role in limiting the brain distribution of vemurafenib. Retrospective analysis was performed on 57 patients with Stage IIIc /IV cutaneous and mucosal melanoma. Patients with BRAF mutation had a higher incidence rate of brain metastases compared to patients without BRAF mutation, although it was not statistically significant (Incidence ratio=1.56; 95% CI=0.70-3.48; P=0.27). Vemurafenib neither reduced the incidence of brain metastases (Incidence ratio = 0.89; 95% CI: 0.30-2.60; P=0.83) nor made significant difference in overall survival. It was observed that treatment with BRAF inhibitor led to improvement in extracranial disease but did not affect progression of intracranial disease. Conclusions: In concordance with preclinical data which indicates that P-gp and BCRP play a significant role in limiting the brain distribution of vemurafenib, the retrospective analysis shows that there is improvement in extracranial disease but progression in intracranial disease with treatment with BRAF inhibitor in patients with metastatic malignant melanoma with BRAF mutation. Development of BRAF inhibitors that are not substrates for P-gp and BCRP or concomitant use of P-gp and BCRP inhibitors with vemurafenib, may be needed in order to control or prevent intracranial disease in these patients. Further analysis to improve statistical power of our observation is underway.