Citations

TPS258 Background: Engineered toxin bodies (ETBs) are comprised of a proprietarily engineered form of Shiga-like Toxin A subunit genetically fused to antibody-like binding domains. ETBs work through novel mechanisms of action & are capable of forcing internalization, self-routing through intracellular compartments to the cytosol & inducing potent cell-kill via the enzymatic & permanent inactivation of ribosomes. MT-5111 is a de-immunized ETB targeting HER2+ solid tumors. Its novel mechanism of action, via enzymatic ribosome inactivation, may not be subject to resistance mechanisms that exist for tyrosine kinase inhibitors, antibody-drug conjugates, or antibody modalities. MT-5111 binds an epitope on HER2, distinct from trastuzumab or pertuzumab, that may provide for combination potential with other HER2-targeting agents. MT-5111 is a 55 kilodalton protein & may have improved tumor penetration capability. The objective of this trial will be to determine the safety, tolerability, & maximum tolerated dose (MTD) of MT-5111 in patients (pts) with advanced HER2+ solid tumors. Methods: This Phase 1, first-in-human, open-label, dose escalation & expansion study will evaluate MT-5111 monotherapy in pts with HER2-positive solid tumors. The primary objective is to determine the MTD; secondary objectives include pharmacokinetics, tumor response & immunogenicity. Part 1 consists of MT-5111 dose escalation (0.5, 1.0, 2.0, 3.0, 4.5, 6.75, 10µg/kg/dose) based on a modified 3+3 design (n≤42 pts); Part 2 (dose expansion) will evaluate MT-5111 at the MTD in ≤98 pts. All pts will be administered MT-5111 over 30 min via IV infusion on Days 1, 8, & 15 of each 21-day cycle until disease progression, unacceptable toxicity, death, withdrawal of consent, or another reason for withdrawal. Part 1 will include pts with any HER2+ solid cancers. Part 2 will enroll 3 expansion cohorts: HER2+ breast (BC), HER2+ gastric or gastroesophageal junction adenocarcinomas (collectively referred as gastroesophageal adenocarcinomas [GEA]) & other HER2+ solid cancers. Immunohistochemistry (IHC) status must be 2+ or 3+, regardless of in situ hybridization (ISH) results; if no IHC is available for pts with BC or GEA, ISH criteria per the American Society of Clinical Oncology College of American Pathologists guidelines will be used. In metastatic cases, HER2 positivity must be demonstrated on metastatic lesions. Pts with HER2+ BC should have had ≥2 lines of HER2-directed therapy; pts with HER2+ GEA should have received or been intolerant to trastuzumab. Pts with evaluable disease may be included in Part 1; in Part 2, all pts must have ≥1 measurable lesion per Response Evaluation Criteria in Solid Tumors v1.1. Further details can be found on clinicaltrials.gov (NCT04029922). Enrollment, which began in September 2019, is ongoing. Clinical trial information: NCT04029922.

Abstract A 40-yr-old male with no significant past medical history presented with sudden onset right-sided retro-orbital headache associated with vision loss after a session of strenuous exercise. Initial assessment with noncontrast head computed tomography at the local emergency department revealed a right sided occipital intracranial hemorrhage (ICH). On arrival the patient ad a left quadrantopsia with Glasgow Coma Scale of 15 and an ICH score of 0. A computed tomographic angiography showed a high density 6 × 9 mm vascular lesion associated with 2 tortuous vessels. Cerebral angiography revealed a right sided dural arteriovenous fistula, Cognard Type IV, with arterial feeders arising from dural branches of the right vertebral artery, the posterior division of the right middle meningeal artery and meningeal branches distal to the neuromeningeal trunk of the left ascending pharyngeal artery. 1 Four days after the ICH event the patient was treated with endovascular Onyx embolization of the fistula, through a transradial approach. Immediate angiographic assessment showed complete obliteration of the dAVF. The patient was discharged home and recovered his visual field deficit over 3 mo. The following operative video includes a discussion of the endovascular technique and treatment nuances associated with the transarterial management of a dural arteriovenous fistula. Patient consent was given prior to the procedure and consent and approval for this operative video was waived due to the retrospective nature of this manuscript and the anonymized video material.

Abstract Wide-necked aneurysms often pose challenges for distal access to the distal vasculature. This 64-yr-old woman without neurological deficits presented with atypical headaches of gradual onset. MRI revealed a large, symptomatic, unruptured carotid terminus aneurysm incorporating the origin of both the middle (MCA) and anterior cerebral arteries (ACA). Its wide neck created significant risks to coil prolapse and parent vessel compromise, risking stroke. With other options of higher risks, we recommended an around-the-world technique. Standard transfemoral access was used to the right internal carotid artery (ICA) with a 6F-Shuttle sheath and intracranial carotid with a 6F-Sofia distal access catheter. With dual-microcatheter access, 1 catheter was placed in the aneurysm dome, a second in the MCA for stent placement. Advancing the wire around the aneurysm first formed a loop from the lateral to medial wall for access to the MCA. The microcatheter was then advanced around the wire into the MCA, keeping the loop within the dome. With the loop's distal tip anchored, the distal end of the stent was deployed and anchored into the MCA. Both pitfalls (ie, lack of sufficient distal access, collapse of stent device during deployment) were resolved using a balloon catheter. With the balloon positioned and inflated as the anchor, the wire and catheter were pulled together. The loop in the aneurysm's dome straightened out across the neck, the stent was advanced into the MCA, and coiling proceeded. A large neck remnant had partially closed on 6-mo follow-up angiogram. Patient consented to undergo the procedure. Illustrations in video published/printed with permission from Mayfield Clinic.

Abstract Sidewall aneurysm treatment often requires complex management strategies. These can include advanced clipping techniques or stent-assisted coiling techniques. Endovascular coiling alone has been associated with high recurrence rates and is often not feasible. 1-4 Flow-diversion embolization has recently become a standard of care for many aneurysms, demonstrating high occlusion rates. 4,5 However, the third generation of coil-assist stents can be delivered with 0.0165” microcatheters, being an ideal adjunct to manage this group of aneurysms in more distal locations. In this video, a 16-yr-old teenager with Parry-Romberg syndrome and congenital adrenal hyperplasia had an incidental finding of a 6.5-mm sidewall aneurysm arising off the angular branch of the left middle cerebral artery, found during the work-up of complex partial seizures. The patient consented to the procedure. Due to his young age and aneurysm size, a decision was made to treat the aneurysm through an endovascular approach. Under general anesthesia, a transfemoral approach was carried out using a 6-French short sheath. A 6-French guiding catheter was left in the distal cervical left internal carotid artery; a 0.0165” microcatheter was used to first deploy a 3.0 × 15 mm Neuroform Atlas stent, completely covering the length of the aneurysm. Then, the stent was traversed with the microcatheter to coil the aneurysm. Follow-up cerebral angiogram confirmed complete occlusion of the aneurysm.

Abstract BACKGROUND Intravenous (IV) alteplase with mechanical thrombectomy has been found to be superior to alteplase alone in select patients with intracranial large vessel occlusion. Current guidelines discourage the use of antiplatelet agents or heparin for 24 h following alteplase. However, their use is often necessary in certain circumstances during thrombectomy procedures. OBJECTIVE To study the safety and outcomes in patients who received blood thinning medications for thrombectomy after IV Tissue-Type plasminogen activator (tPA). METHODS This is a multicenter retrospective review of the use of antiplatelet agents and/or heparin in patients within 24 h following tPA administration. Patient demographics, comorbidities, bleeding complications, and discharge outcomes were collected. RESULTS A series of 88 patients at 9 centers received antiplatelet medications and/or heparin anticoagulation following IV alteplase for revascularization procedures requiring stenting. The mean National Institutes of Health Stroke Scale (NIHSS) on admission was 14.6. Reasons for use of a stent included internal carotid artery occlusion in 74% of patients. Thrombolysis in cerebral infarction (TICI) 2b-3 revascularization was accomplished in 90% of patients. The rate of symptomatic intracranial hemorrhage (sICH) was 8%; this was not significantly different than the sICH rate for a matched group of patients not receiving antiplatelets or heparin during the same time frame. Functional independence at 90 d (modified Rankin Scale 0-2) was seen in 57.8% of patients. All-cause mortality was 12%. CONCLUSION The use of antiplatelet agents and heparin for stroke interventions following IV alteplase appears to be safe without significant increased risk of hemorrhagic complications in this group of patients when compared to control data and randomized controlled trials.

The coronavirus disease 2019 (COVID-19) pandemic is associated with significant morbidity and mortality throughout the world, predominantly due to lung and cardiovascular injury. The virus responsible for COVID-19—severe acute respiratory syndrome coronavirus 2—gains entry into host cells via ACE2 (angiotensin-converting enzyme 2). ACE2 is a primary enzyme within the key counter-regulatory pathway of the renin-angiotensin system (RAS), which acts to oppose the actions of Ang (angiotensin) II by generating Ang-(1–7) to reduce inflammation and fibrosis and mitigate end organ damage. As COVID-19 spans multiple organ systems linked to the cardiovascular system, it is imperative to understand clearly how severe acute respiratory syndrome coronavirus 2 may affect the multifaceted RAS. In addition, recognition of the role of ACE2 and the RAS in COVID-19 has renewed interest in its role in the pathophysiology of cardiovascular disease in general. We provide researchers with a framework of best practices in basic and clinical research to interrogate the RAS using appropriate methodology, especially those who are relatively new to the field. This is crucial, as there are many limitations inherent in investigating the RAS in experimental models and in humans. We discuss sound methodological approaches to quantifying enzyme content and activity (ACE, ACE2), peptides (Ang II, Ang-[1–7]), and receptors (types 1 and 2 Ang II receptors, Mas receptor). Our goal is to ensure appropriate research methodology for investigations of the RAS in patients with severe acute respiratory syndrome coronavirus 2 and COVID-19 to ensure optimal rigor and reproducibility and appropriate interpretation of results from these investigations.

8599 Background: MM survival varies enormously from few months to more than a decade. Baseline prognostic factors (PF) have been identified that are linked to survival outcomes, especially B2M and albumin. MM survival plots are typically characterized by 3 segments of slopes with decreasing steepness, suggesting that different PF may govern these time segments. Methods: We therefore examined, in S9321, PF that were associated with overall survival (OS) from baseline (BL) and from 3 subsequent landmarks 3, 5, and 7 years later (LM3, LM5, LM7). With a median follow-up of 9 years, OS and EFS were virtually identical in transplant and standard therapy arms so that the data were pooled. Results: Median OS and EFS for 817 eligible patients are 48 and 22 months. The BL model identified age (>60yr), hemoglobin (<10g/gL), platelet count (<130,000/uL), albumin (<3.5g/dL), B2M (>3.5g/dL), calcium (>10mg/dL), creatinine (>2mg/dL), LDH (>190U/L), performance status (PS, >1), IL-6 level (>140mg/L) and plasma cell labeling index (PCLI, >1%) as being univariately associated with short OS, while age (p=0.002), platelet count (p=0.04), calcium (p<0.001), B2M (p=0.002), LDH (p=0.010) and PCLI (p<0.001) retained significance in multivariate analysis. For the LM3 analyses, age (p=0.006) and B2M (p=0.009) were independently associated with poor OS, whereas PCLI was the only PF associated with LM5 (p=0.026) and age with LM7 (p<0.001). While associated univariately with OS from BL, CRP, platelet count, hemoglobin, albumin, calcium, creatinine, LDH, IL6 and PS all failed to affect OS from later LM times. Conclusions: Whereas the initial 3 years of OS are governed by a combination of features related to disease aggressiveness (LDH, calcium, albumin, CRP), tumor burden (hemoglobin, platelet count) and host tolerance (PS, creatinine), B2M and PCLI as reflectors of tumor burden and proliferation have sustained long-term OS implications. The age factor figures in partly due to death from other causes. In an era of ever-improving survival outcomes, such LM-based PF analysis may reveal trial-specific differences and thus provide guidance toward individualizing therapy. [Table: see text]

Glembatumumab vedotin (CDX-011, GV) is a fully human Immunoglobulin G2 monoclonal antibody directed against glycoprotein NMB coupled via a peptide linker to monomethyl auristatin E (MMAE), a potent cytotoxic microtubule inhibitor. This phase II study evaluated the overall response rate and safety of GV, glycoprotein NMB (GPNMB) expression, and survival in patients with metastatic uveal melanoma. Eligible patients with metastatic uveal melanoma who had not previously been treated with chemotherapy received GV 1.9 mg/kg every three weeks. The primary endpoint was the objective response rate (ORR). Secondary endpoints included GPNMB expression, progression-free survival (PFS), overall survival (OS), and toxicity analysis. GPNMB expression was assessed pre- and post-treatment via immunohistochemistry for patients with available tumor tissue. Out of 35 patients who received treatment, two patients had confirmed partial responses (PRs; 6%), and 18 patients had a stable disease (SD; 51%) as the best objective response. 38% of the patients had stable disease >100 days. The grade 3 or 4 toxicities that occurred in two or more patients were neutropenia, rash, hyponatremia, and vomiting. The median progression-free survival was 3.1 months (95% CI: 1.5–5.6), and the median overall survival was 11.9 months (95% CI 9.0–16.9) in the evaluable study population. GV is well-tolerated in metastatic uveal melanoma. The disease control rate was 57% despite a low objective response rate. Exploratory immune correlation studies are underway to provide insight into target saturation, combination strategies, and antigen release.

Abstract Background The incidence of very early onset inflammatory bowel disease (VEOIBD) is increasing, yet the phenotype and natural history of VEOIBD are not well described. Methods We performed a retrospective cohort study of patients diagnosed with VEOIBD (6 years of age and younger) between 2008 and 2013 at 25 North American centers. Eligible patients at each center were randomly selected for chart review. We abstracted data at diagnosis and at 1, 3, and 5 years after diagnosis. We compared the clinical features and outcomes with VEOIBD diagnosed younger than 3 years of age with children diagnosed with VEOIBD at age 3 to 6 years. Results The study population included 269 children (105 [39%] Crohn’s disease, 106 [39%] ulcerative colitis, and 58 [22%] IBD unclassified). The median age of diagnosis was 4.2 years (interquartile range 2.9–5.2). Most (94%) Crohn’s disease patients had inflammatory disease behavior (B1). Isolated colitis (L2) was the most common disease location (70% of children diagnosed younger than 3 years vs 43% of children diagnosed 3 years and older; P = 0.10). By the end of follow-up, stricturing/penetrating occurred in 7 (6.6%) children. The risk of any bowel surgery in Crohn’s disease was 3% by 1 year, 12% by 3 years, and 15% by 5 years and did not differ by age at diagnosis. Most ulcerative colitis patients had pancolitis (57% of children diagnosed younger than 3 years vs 45% of children diagnosed 3 years and older; P = 0.18). The risk of colectomy in ulcerative colitis/IBD unclassified was 0% by 1 year, 3% by 3 years, and 14% by 5 years and did not differ by age of diagnosis. Conclusions Very early onset inflammatory bowel disease has a distinct phenotype with predominantly colonic involvement and infrequent stricturing/penetrating disease. The cumulative risk of bowel surgery in children with VEOIBD was approximately 14%–15% by 5 years. These data can be used to provide anticipatory guidance in this emerging patient population.