Smestad, John

Abstract Background Pembrolizumab is approved for advanced cutaneous melanoma (aCM). Cabozantinib, an oral multi‐tyrosine kinase inhibitor, has demonstrated antitumor activity as monotherapy or in combination with anti‐PD‐1 therapy in malignancies. The objective of this study was to determine the safety and efficacy of cabozantinib and pembrolizumab for patients with aCM. Methods This phase 1b/2 study enrolled 28 patients with unresectable aCM. In phase 1b, escalating dose levels of cabozantinib (20 mg, 40 mg, and 60 mg) were administered concurrently with pembrolizumab 200 mg intravenously every 3 weeks using a 3 + 3 design to determine recommended phase 2 dose (RP2D). In phase 2, patients received cabozantinib at RP2D in combination with pembrolizumab using a Simon 2 stage design. Primary end point of phase 2 was overall response rate (ORR). Secondary end points included disease control rate, progression‐free survival (PFS), and overall survival (OS). Results Phase 1b enrolled eight patients, cabozantinib 40 mg daily dose level was selected as RP2D. Response rate in stage 1 exceeded predefined criteria for proceeding to expansion phase; however, phase 2 was terminated after 20 patients due to low accrual in the setting of evolving standard of care. Among all treated patients, the most common grade ≥3 toxicities were hypertension ( n = 10, 36%), hypokalemia ( n = 5, 18%), hypophosphatemia ( n = 4, 14%), and ALT elevation ( n = 4, 14%). Among 20 patients treated in phase 2, ORR was 45%, median PFS was 6.6 months, and median OS was 29.5 months. Conclusions Cabozantinib and pembrolizumab combination was explored in treatment‐naive aCM. Toxicity was consistent with known profiles, but discontinuation rates were notable.

We previously reported the in vitro selection and characterization of a DNA aptamer capable of stimulating remyelination in a mouse model of multiple sclerosis. This aptamer was selected for its ability to bind to suspensions of crude murine myelin in vitro . Our initial studies in vitro and in vivo involved a 40-nucleotide derivative (LJM-3064) of the original 100-nucleotide aptamer. LJM-3064 retained robust myelin-binding properties. Structural characterization of LJM-3064 revealed that the guanosine-rich 5′ half of the sequence forms different G-quadruplex-type structures that are variably stable in the presence of physiologically relevant ions. We hypothesized that this structured domain is sufficient for myelin binding. In this study, we confirm that a 20-nucleotide DNA, corresponding to the 5′ half of LJM-3064, retains myelin-binding properties. We then optimize this minimal myelin-binding aptamer via systematic evolution of ligands by exponential enrichment after sparse rerandomization. We report a sequence variant (LJM-5708) of the 20-nucleotide myelin-binding aptamer with enhanced myelin-binding properties and the ability to bind cultured human oligodendroglioma cells in vitro , providing the first evidence of cross-species reactivity of this myelin-binding aptamer. As our formulation of DNA aptamers for in vivo remyelination therapy involves conjugation to streptavidin, we verified that the myelin-binding properties of LJM-5708 were retained in conjugates to avidin, streptavidin, and neutravidin. DNA aptamer LJM-5708 is a lead for further preclinical development of remyelinating aptamer technologies.

Summary Objective The outcomes of patients with metastatic phaeochromocytoma (PHEO) and paraganglioma (PGL) are unclear. We performed a systematic review and meta‐analysis of baseline characteristics and mortality rates of patients with metastatic PHEO and PGL (PPGL). Design Ovid MEDLINE In‐Process & Other Non‐Indexed Citations, Ovid MEDLINE, Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, Scopus, Web of Science, and references of key articles were searched from inception to 2016. Patients Studies comprised ≥20 patients with metastatic PPGL and reported baseline characteristics and follow‐up data. Measurements Reviewers extracted standardized data and assessed risk of bias using a modified Newcastle‐Ottawa tool. Random‐effects meta‐analysis was used to pool event rates across studies. Results Twenty retrospective noncomparative studies reported on 1338 patients with metastatic PHEO (685/1296, 52.9%) and PGL (611/1296, 47.1%), diagnosed at a mean age of 43.9 ± 5.2 years. Mean follow‐up was 6.3 ± 3.2 years. Of 532 patients with reported data, 40.4% had synchronous metastases. Five‐year (7 studies, n = 738) and 10‐year (2 studies, n = 55) mortality rates for patients with metastatic PPGL were 37% (95% CI, 24%‐51%) and 29% (95% CI, 17%‐42%), respectively. Higher mortality was associated with male sex (RR 1.50; 95% CI, 1.11‐2.02) and synchronous metastases (RR 2.43; 95% CI, 1.01‐5.85). Conclusions Available low‐quality evidence from heterogeneous studies suggests low mortality rates of patients with metastatic PPGL. Male sex and synchronous metastases correlated with increased mortality. The outcomes of patients with metastatic PPGL have been inadequately assessed, indicating the need for carefully planned prospective studies.

DNA aptamer oligonucleotides and their protein conjugates show promise as therapeutics in animal models of diseases such as multiple sclerosis. These molecules are large and highly charged, raising questions about their biodistribution and pharmacokinetics in mammals. Here we exploit the power of quantitative polymerase chain reaction to accurately quantitate the tissue distribution of 40-nucleotide DNA aptamers and their streptavidin conjugates after intraperitoneal injection in mice. We show remarkably rapid distribution to peripheral tissues including the central nervous system. Modeling of tissue distribution data reveals the importance of DNA aptamer sequence, 3′ modification, and protein conjugation in enhancing tissue exposure. These data help to interpret the previously observed effectiveness of aptamer conjugates, as opposed to free aptamers, in stimulating central nervous system remyelination in a mouse model of multiple sclerosis.