The ATM kinase inhibitor AZ31 and ATR kinase inhibitor AZD6738 are in various phases of preclinical and clinical evaluation for their ability to potentiate chemoradiation. To support the preclinical evaluation of their pharmacokinetics, we developed and validated an LC-MS/MS assay for the simultaneous quantification of AZ31 and AZD6738 in mouse plasma. A “dilute and shoot” method was used to precipitate proteins from a sample volume of 50 μL. Chromatographic separation was achieved using a Phenomenex Polar-RP column and a gradient mobile phase consisting of methanol-water with 0.1% formic acid. Detection was accomplished using a Waters Quattro Micro mass spectrometer in positive ionization mode. The assay utilizing 50 μL sample was linear from 10–5,000 ng/mL and determined to be both accurate (−8.2 to 8.6%) and precise (<5.4% CV) and achieved the criteria for U.S. FDA guidance for bioanalytical method validation. Quantification was achieved in mouse tissue homogenate using a separate 200 μL sample preparation. This LC-MS/MS assay will be essential for determining the tissue distribution and pharmacokinetics in future mouse studies.

Intro: Tibial tuberosity avulsion fractures are rare fracture patterns accounting for less than 1% of all pediatric fractures. These fractures occur when there is a sudden unbalancing of forces through the patellar tendon that separates the tibial tubercle from the anterior portion of the proximal tibia. These forces are commonly introduced in sporting activities and show a predominance for adolescent males. Treatment with open reduction internal fixation commonly results in favorable outcomes with minimal complications. In this presentation, we explore a case of a tibial tuberosity avulsion fracture and give an in-depth review of all aspects concerning this fracture pattern. Case Description: A 14-year-old male with no significant past medical history presented via emergency medical services after a ground level fall while playing basketball. Radiographs of the left knee and tibia revealed an Ogden Type III, distracted avulsion fracture of the tibial tuberosity with suprapatellar effusion. Surgical intervention was achieved through open reduction internal fixation of the left tibial tubercle. Discussion: Although a relatively rare fracture pattern, this case demonstrates a classic presentation and treatment of a tibial tuberosity avulsion fracture. This case serves as a reminder that despite the rarity of the injury, a clinician with an appropriate index of suspicion can accurately diagnose and treat this fracture and achieve positive outcomes in returning the patient to pre-injury activities. For those reasons, we provide a comprehensive overview of all aspects regarding this fracture pattern including the anatomy, embryology, mechanism of action, predisposing conditions, treatment considerations, complications and associated injuries.