Improved safety and efficacy of 213Bi-DOTATATE-targeted alpha therapy of somatostatin receptor-expressing neuroendocrine tumors in mice pre-treated with L-lysine

Background

Targeted alpha therapy (TAT) offers advantages over current β-emitting conjugates for peptide receptor radionuclide therapy (PRRT) of neuroendocrine tumors. PRRT with ¹⁷⁷Lu-DOTATATE or ⁹⁰Y-DOTATOC has shown dose-limiting nephrotoxicity due to radiopeptide retention in the proximal tubules. Pharmacological protection can reduce renal uptake of radiopeptides, e.g., positively charged amino acids, to saturate in the proximal tubules, thereby enabling higher radioactivity to be safely administered. The aim of this preclinical study was to evaluate the therapeutic effect of ²¹³Bi-DOTATATE with and without renal protection using L-lysine in mice. Tumor uptake and kinetics as a function of injected mass of peptide (range 0.03–3 nmol) were investigated using ¹¹¹In-DOTATATE. These results allowed estimation of the mean radiation absorbed tumor dose for ²¹³Bi-DOTATATE. Pharmacokinetics and dosimetry of ²¹³Bi-DOTATATE was determined in mice, in combination with renal protection. A dose escalation study with ²¹³Bi-DOTATATE was performed to determine the maximum tolerated dose (MTD) with and without pre-administration of l-lysine as for renal protection. Neutrophil gelatinase-associated lipocalin (NGAL) served as renal biomarker to determine kidney injury.

Results

The maximum mean radiation absorbed tumor dose occurred at 0.03 nmol and the minimum at 3 nmol. Similar mean radiation absorbed tumor doses were determined for 0.1 and 0.3 nmol with a mean radiation absorbed dose of approximately 0.5 Gy/MBq ²¹³Bi-DOTATATE. The optimal mass of injected peptide was found to be 0.3 nmol. Tumor uptake was similar for ¹¹¹In-DOTATATE and ²¹³Bi-DOTATATE at 0.3 nmol peptide. Lysine reduced the renal uptake of ²¹³Bi-DOTATATE by 50% with no effect on the tumor uptake. The MTD was <13.0 ± 1.6 MBq in absence of l-lysine and 21.7 ± 1.9 MBq with l-lysine renal protection, both imparting an LD₅₀ mean renal radiation absorbed dose of 20 Gy. A correlation was found between the amount of injected radioactivity and NGAL levels.

Conclusions

The therapeutic potential of ²¹³Bi-DOTATATE was illustrated by significantly decreased tumor burden and improved overall survival. Renal protection with l-lysine immediately prior to TAT with ²¹³Bi-DOTATATE prolonged survival providing substantial evidence for pharmacological nephron blockade to mitigate nephrotoxicity.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-016-0240-5) contains supplementary material, which is available to authorized users.

Decreasing sound and vibration during ground transport of infants with very low birth weight

OBJECTIVE

To measure the effectiveness of modifications to reduce sound and vibration during interhospital ground transport of a simulated infant with very low birth weight (VLBW) and a gestational age of 30 weeks, a period of high susceptibility to germinal matrix and intraventricular hemorrhage.

STUDY DESIGN

Researchers measured vibration and sound levels during infant transport, and compared levels after modifications to the transport incubator mattresses, addition of vibration isolators under incubator wheels, addition of mass to the incubator mattress and addition of incubator acoustic cover.

RESULT

Modifications did not decrease sound levels inside the transport incubator during transport. The combination of a gel mattress over an air chambered mattress was effective in decreasing vibration levels for the 1368 g simulated infant.

CONCLUSION

Transport mattress effectiveness in decreasing vibration is influenced by infant weight. Modifications that decrease vibration for infants weighing 2000 g are not effective for infants with VLBW. Sound levels are not affected by incubator covers, suggesting that sound is transmitted into the incubator as a low-frequency vibration through the incubator's contact with the ambulance. Medical transportation can apply industrial methods of vibration and sound control to protect infants with VLBW from excessive physical strain of transport during vulnerable periods of development.

An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe

We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase of a double beta decay experiment, nEXO. The goal is to identify the Ba ion resulting from an extremely rare nuclear decay of the isotope (136)Xe, hence providing a confirmation of the occurrence of the decay. This is achieved through Resonance Ionization Spectroscopy (RIS). In the test setup described here, Ba ions can be produced in liquid xenon or vacuum and collected on a clean substrate. This substrate is then removed to an analysis chamber under vacuum, where laser-induced thermal desorption and RIS are used with time-of-flight mass spectroscopy for positive identification of the barium decay product.

Tibial bone versican content decreases with zoledronate treatment in adult mice

In bone remodeling, the expression and turnover of the proteoglycans versican and aggrecan are poorly understood. We report changes in adult mouse bone contents of versican and aggrecan associated with both age and treatment with the drug zoledronate. The data may have implications for experimental animal models of osteoporosis and related conditions.

INTRODUCTION

Versican and aggrecan are large, aggregating proteoglycans involved in skeletal development, but little is known about their roles in bone remodeling. The purpose of this study was to investigate versican and aggrecan contents in adult mouse bones, and changes in their contents in response to the bisphosphonate zoledronate (ZOL).

METHODS

Mice (9 weeks old) were treated with 125 μg/kg ZOL or vehicle for 3 or 15 weeks. Versican and aggrecan were isolated from tibial bones for Western blotting, automated integrated densitometry, and analysis (two-way ANOVA, α = 0.05).

RESULTS

In ZOL-treated mouse bones, compared to vehicle, 340 and 60 kDa versican content decreased significantly, and 100 and 60 kDa aggrecan content decreased significantly (drug effect). In 24-week-old mouse bones, compared to 12 weeks, statistically significant decreases were observed in 340, 80, 60, and 11 kDa versican, and in 100, 70, and 40 kDa aggrecan (age effect). There was a statistically significant ZOL-age interaction for 330 kDa aggrecan.

CONCLUSION

This is the first study to assess physiological versican and aggrecan adaptations in adult mammalian bone tissue, in the presence and absence of ZOL. We observed large decreases in some versican and aggrecan species from 12 to 24 weeks. We also observed decreases in several versican and aggrecan species in the presence of ZOL. This indicates that bone proteoglycan expression and turnover may be important in bone remodeling.

Clinical and radiographic outcomes of the mobility total ankle arthroplasty system: early results from a prospective multicenter study

BACKGROUND

The Mobility Total Ankle System is a third-generation design consisting of a 3-component, cementless, unconstrained, mobile-bearing prosthesis. This study reports the early results of a prospective multicenter study of the Mobility prosthesis.

METHODS

Eighty-eight Mobility total ankle arthroplasties (TAAs) were implanted in 85 patients. The most common underlying diagnosis was posttraumatic arthritis (53%). Ankles were classified according to the Canadian Orthopedic Foot and Ankle Society (COFAS) end-stage ankle arthritis classification system. Coronal plane deformity was quantified preoperatively. Patients were reviewed at regular intervals postoperatively, with clinical and radiographic assessment. The mean follow-up time was 40 months (range, 30-60 months).

RESULTS

Type 1 ankle arthritis was demonstrated in 44 ankles (50%). No patient had preoperative coronal plane angulation greater than 20 degrees. In 32 ankles (36%) the preoperative coronal alignment was neutral, and in 34 ankles (39%) the deformity was less than 10 degrees. The mean American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot score improved from 38.2 (range, 12-59) preoperatively to 74.8 (range, 46-100) postoperatively. Bone-implant interface abnormalities were identified in 33 ankles with a retained prostheses (43%). Thirty (91%) of these involved zones around the tibial plate. In total, 8 TAAs required revision, 6 for aseptic loosening, 1 for talar migration, and 1 for deep infection. There was 1 conversion to arthrodesis for component malpositioning and 1 transtibial amputation for chronic regional pain syndrome. Six patients were being investigated for ongoing pain. The cumulative survival was 89.6% (95% confidence interval, 80.8-94.8) at 3 years and 88.4% (95% confidence interval, 79.3-93.9) at 4 years.

CONCLUSION

Early results of the Mobility TAA for independent researchers do not match those reported by other surgeons. Good pain relief and improved function were achieved postoperatively in 72 ankles (82%). High rates of bone-implant interface abnormalities around the tibial plate are concerning but require longer follow-up to determine their clinical significance.

Search for neutrinoless double-beta decay in 136Xe with EXO-200

We report on a search for neutrinoless double-beta decay of 136Xe with EXO-200. No signal is observed for an exposure of 32.5 kg yr, with a background of ∼1.5×10(-3)  kg(-1) yr(-1)  keV(-1) in the ±1σ region of interest. This sets a lower limit on the half-life of the neutrinoless double-beta decay T(1/2)(0νββ)(136Xe)>1.6×10(25)  yr (90% C.L.), corresponding to effective Majorana masses of less than 140-380 meV, depending on the matrix element calculation.