Efficacy and Effect of Cabozantinib on Bone Metastases in Treatment-naive Castration-resistant Prostate Cancer

BACKGROUND

Cabozantinib is active in advanced prostate cancer with improvement on bone scans in men on phase II trials. This trial evaluated the efficacy and changes in bone lesions in men with metastatic castration-resistant prostate cancer (mCRPC) treated with cabozantinib.

PATIENTS AND METHODS

Eligible patients with mCRPC involving bone underwent biopsy of a bone lesion followed by cabozantinib starting at 60 mg daily and continuing until progression or intolerable toxicity. The primary study endpoint was progression-free survival at 12 weeks. The bone lesion was rebiopsied at 6 weeks. Expression of CMET, phospho-CMET, and VEGFR2 was assayed by immunohistochemistry. Serum was obtained at baseline, and at 3, 6, and 12 weeks and assayed for bone remodeling markers.

RESULTS

A total of 25 patients were enrolled: 22 were evaluable, and 3 were excluded before receiving cabozantinib. At 12 weeks, 17 (77%) of 22 patients had stable disease or better. The median time on treatment was 24 weeks (range, 3-112 weeks). The overall median progression-free survival was 43.7 weeks (95% confidence interval, 23.7-97.0 weeks). Eight (36%) of 22 patients had markedly reduced uptake on bone scan. Patients with significant response on bone scan had higher bone morphogenic protein-2 levels at baseline, stable N-telopeptides levels, increased vascular endothelial growth factor receptor 2 expression, and a trend towards increased phospho-CMET while on cabozantinib compared with patients with stable disease.

CONCLUSIONS

Cabozantinib is active in men with mCRPC, inducing significant changes on bone scan in one-third of patients with changes in markers of bone formation and the tumor microenvironment.

Fractures Around the Shoulder: Radiologic Update on Surgical Fixation Techniques

Although radiologists are likely familiar with basic fracture patterns around the shoulder, certain fracture types in this area have particularly relevant and controversial clinical management issues. These include proximal humeral fractures, in which conservative management is favored but some patients receive surgical treatment; glenoid fractures and Hill-Sachs lesions, in which surgery may be performed depending on the amount of bone loss; and distal clavicular fractures, in which certain displaced fractures have high rates of nonunion, but there is no clearly favored surgical technique. Knowledge of the different clinical issues and surgical options can aid the radiologist in identifying key imaging findings and creating a useful report.

Normal and Injured Ankle Ligaments on Ultrasonography With Magnetic Resonance Imaging Correlation

Ultrasonography (US) has been increasingly used in the evaluation of ankle ligamentous injuries given its advantages as a dynamic, efficient, noninvasive, and cost-effective imaging method. Understanding the anatomy of the ankle ligaments is critical for correct diagnosis and treatment. This pictorial essay describes and illustrates the US scanning technique and potential pitfalls in evaluating the ankle ligaments and also provides an overview of the US appearance of normal and injured ankle ligaments with magnetic resonance imaging correlation. Highlighted structures include the lateral complex, medial/deltoid complex, spring (calcaneonavicular) ligament complex, and syndesmosis.

Imaging appearance following surgical decompression of the ulnar nerve

Ulnar neuropathy at the elbow is the second most common entrapment neuropathy of the upper extremity. Yet, there is a paucity of literature focusing on the imaging appearance following surgical decompression of the ulnar nerve at the elbow. Diagnostic imaging studies obtained after surgical decompression at The University of Michigan were reviewed and imaging findings were documented. We aim to describe the various techniques of ulnar nerve decompression and corresponding post-operative appearance on imaging. Potential complications following decompression will also be described with imaging and clinical correlation of recalcitrant ulnar neuropathy. It is important for the radiologist who performs MRI or ultrasound of the elbow to be aware of the various ulnar nerve decompression procedures. This knowledge will facilitate rapid and accurate diagnosis of normal and abnormal appearance of the ulnar nerve in this context.

Imaging appearance of well-differentiated liposarcomas with myxoid stroma

OBJECTIVE

Describe the imaging appearance of well-differentiated liposarcoma with myxoid stroma (WDLMS) and correlate with histopathology.

MATERIALS AND METHODS

A keyword search of the institution medical records was performed from 1 January 2000 to 30 June 2017. The histopathology slides of cases identified in this fashion were then reviewed by a pathologist. Additional cases were prospectively collected from extramural referrals and tumor boards. Diagnostic imaging studies of pathologically proven cases of WDLMS were then reviewed in consensus and correlated with pathology.

RESULTS

Ten cases of pathologically proven WDLMS were identified (7 men, 3 women, ages 26-81). Tumor location included the retroperitoneum (n = 5), thigh (n = 4), and the shin (n = 1). Nine patients had macroscopic fat on imaging. The nonlipomatous components had a variable appearance, including septal, nodular, and lacelike patterns. Two cases included two distinct areas that were predominantly myxoid or lipomatous ("bi-morphic"). One tumor had no macroscopic fat on imaging. On CT, the nonlipomatous nodular components were hypodense/had hypodense areas. On MRI, the nodular components had intermediate/bright T2W signal. Interval nonlipomatous nodular growth was identified in 3 cases.

CONCLUSION

WDLMS may present on imaging as a mass with variable morphology and amounts of nonlipomatous components. Histopathological diagnosis of WDLMS is challenging and imaging correlation may be helpful, as this tumor may have ≥50% fatty volume, may have a myxoid nodular component or bi-morphic appearance, or may be located in the retroperitoneum, features that are unusual for myxoid liposarcoma. WDLMS with a nodular component cannot be distinguished from dedifferentiated liposarcoma based on imaging alone.

The 9 Habits of Highly Effective Radiologists

Stephen R. Covey's landmark work in the field of effectiveness and professional development delineated first 7, then ultimately eight, habits of highly effective people with applicability to all professions.¹ This article describes the eight habits in specific relation to the radiologist, and proposes a ninth habit to help one bring a positive and centered approach during the journey to effectiveness and beyond.

Role of Sonography in Clinically Occult Femoral Hernias

OBJECTIVES

The purpose of this article is to evaluate the diagnostic accuracy of sonography in clinically occult femoral hernias and to describe our sonographic technique.

METHODS

The clinical and imaging data for 93 outpatients referred by general surgeons, all of whom underwent sonographic evaluation and surgery, were reviewed retrospectively. Of these, 55 patients who underwent surgical exploration for groin hernias within 3 months of sonography and met all inclusion criteria were included in the study. The sonographic technique involves using the pubic tubercle as an osseous landmark to identify and appropriately visualize the femoral canal. The Valsalva maneuver is then used to differentiate the movement of normal fat (a potential pitfall) from true herniation in the femoral canal. Surgical findings were used as the reference standard by which sonographic results were judged. Two-by-two contingency tables were used to calculate the sensitivity, specificity, positive predictive value, and negative predictive value.

RESULTS

In these 55 patients, surgery revealed 15 femoral hernias. Eight femoral hernias occurred in women, and 7 occurred in men. For diagnosing femoral hernias, sonography demonstrated sensitivity of 80%, specificity of 88%, a positive predictive value of 71%, and a negative predictive value of 92%. True-positive cases of femoral hernias have a sonographic appearance of a hypoechoic sac with speckled internal echoes. When examining during the Valsalva maneuver, a femoral hernia passes deep to the inguinal ligament, expands the femoral canal, displacing the normal canal fat, and effaces the femoral vein.

CONCLUSIONS

Sonography can exclude femoral hernias with high confidence in light of its exceptional negative predictive value. With attention to technique and imaging criteria, the diagnostic accuracy of sonography can be enhanced.

Potential for Early Fracture Risk Assessment in Patients with Metastatic Bone Disease using Parametric Response Mapping of CT Images

Pathologic vertebral compression fractures (PVCFs) cause significant morbidity in patients with metastatic bone disease. Limitations in existing clinical biomarkers leave clinicians without reliable metrics for predicting PVCF, thus impeding efforts to prevent this severe complication. To establish the feasibility of a new method for defining the risk of a PVCF, we retrospectively analyzed serial computed tomography (CT) scans from 5 breast cancer patients using parametric response mapping (PRM) to quantify dynamic bone miniral density (BMD) changes that preceded an event. Vertebrae segmented from each scan were registered to the same spatial frame and voxel classification was accomplished using a predetermined threshold of change in Hounsfield units (HU), resulting in relative volumes of increased (PRM_HU+), decreased (PRM_HU−), or unchanged (PRM_HU0) attenuation. A total of 7 PVCFs were compared to undiseased vertebrae in each patient serving as controls. A receiver operator curve (ROC) analysis identified optimal imaging times for group stratification. BMD changes were apparent by an elevated PRM_HU+ as early as 1 year before fracture. ROC analysis showed poor performance of PRM_HU− in stratifying PVCFs versus controls. As early as 6 months before PVCF, PRM_HU+ was significantly larger (12.9 ± 11.6%) than control vertebrae (2.3 ± 2.5%), with an area under the curve of 0.918 from an ROC analysis. Mean HU changes were also significant between PVCF (26.8 ± 26.9%) and control (−2.2 ± 22.0%) over the same period. A PRM analysis of BMD changes using standard CT imaging was sensitive for spatially resolving changes that preceded structural failure in these patients.

Sonography of traumatic quadriceps tendon tears with surgical correlation

OBJECTIVES

Using surgical correlation as the reference standard, the purpose of this study was to assess the ability of sonography to detect quadriceps tendon tears that require surgical treatment (high-grade partial tears and complete ruptures).

METHODS

Two hundred thirty-nine consecutive sonographic reports of the knee (May 2001 to October 2008) with subsequent surgical correlation were retrospectively reviewed for surgical intervention on the quadriceps tendon. All sonograms were blindly and retrospectively reviewed. Surgical findings were compared with results from the consensus review. Results from the original sonographic reports (nonretrospective interpretation) were also compared with the surgical findings.

RESULTS

On the retrospective consensus review, the sensitivity (23 of 23), specificity (16 of 16), and accuracy (39 of 39) were 100% for identifying high-grade partial tears or complete ruptures versus a normal quadriceps tendon. For the original, nonretrospective sonographic reports, 22 of 23 high-grade partial tears or complete ruptures (96%) were correctly diagnosed.

CONCLUSIONS

Sonography is an effective tool for identifying quadriceps tendon tears that require surgical treatment (high-grade partial tears and complete ruptures).

Using computed tomography to assess proximal humerus fractures

Computed tomography (CT) scans are often used to evaluate proximal humerus fractures. We conducted a study to determine if use of preoperative CT scans affects surgical decision-making with respect to proximal humerus fractures. Three board-certified orthopedic surgeons interpreted plain radiographs of 40 proximal humerus fractures and then CT scans with reformatted images. Results were assessed for interrater reliability. Use of CT significantly improved interobserver reliability in fracture characterization and assessment. Surgeons were more likely to identify a displaced fracture (P < .01), an impaction (P < .001), and involvement of the anatomical neck (P < .03). However, CT did not improve agreement with use of AO (Arbeitsgemeinschaft für Osteosynthesefragen) fracture classification and did not significantly alter treatment recommendations. CT scans provide more detail about the character of proximal humerus fractures (displacement, involved segments) but do not significantly influence surgical treatment recommendations when compared with plain radiographs alone.

A phase II trial of cabozantinib (Cabo) in patients (pts) with castrate-resistant prostate cancer (CRPC) metastatic to bone (NCT01428219)

TPS5094

Background: MET overexpression predicts prostate cancer invasion and bone metastasis; inhibition of MET/VEGF pathways has synergistic activity in CRPC (Knudsen et al. Adv Cancer Res 2004; Aftab et al. Clin Transl Oncol 2011). Cabo is a small molecule that inhibits multiple receptor tyrosine kinases, including MET and VEGFR2. A phase II randomized discontinuation trial of Cabo showed clinical activity in CRPC, including reduction of soft tissue lesions, prolongation of progression-free survival (PFS), resolution of bone scans, and reductions in bone turnover markers, pain and narcotic use (Smith et al, JCO 2013). To further define the activity of Cabo in pts with CRPC and bone metastases, we launched a phase II trial to characterize the effects of Cabo on bone metabolism and tumor activity in prostate cancer bone lesions. We hypothesize that the clinical activity of Cabo correlates with measurable pharmacodynamic effects on bone micro-environment. Methods: After informed consent, chemotherapy-naive pts with progressive CRPC and bone metastases accessible to CT-guided biopsy, adequate performance status/organ function, are treated with Cabo 60 mg once daily. Primary endpoint: proportion of pts progression-free (PF) at 12 weeks. Secondary endpoints: safety, PFS, response proportion/duration, PSA response, PSA time-to-progression. A Simon's two-stage mini-max design permits early termination after the first 27 evaluable pts in case of unfavorable results. Alternatively, up to 46 evaluable pts will be accrued. Cabo would not be of interest if the 12-week PF proportion is <0.45; it would be of definite clinical interest if the 12-week PF proportion is >0.65 (5% type I error, 85% power). Perfusion/diffusion-weighted MRI (parametric response maps) and bone lesion biopsies are required at baseline and 6 weeks after starting Cabo. Doxycycline is administered prior to bone biopsy for bone labeling. Bone cores are sent for dynamic histomorphometry and immunohistochemistry (phospho-MET/MET, phospho-VEGFR2/VEGFR2, phospho-Akt/Akt). Serum is collected at several time-points to measure markers of bone metabolism. 13 of 27 first-stage pts have been enrolled and started Cabo. Clinical trial information: NCT01428219.

Analysis of diffusion changes in posttraumatic bone marrow using navigator-corrected diffusion gradients

OBJECTIVE

This study was undertaken to analyze diffusion characteristics of normal and posttraumatic bone marrow.

MATERIALS AND METHODS

Fifty consecutive patients with knee pain underwent both conventional and diffusion-weighted MR imaging (b values, 0-980 sec/mm2). Diffusion maps derived from source data were analyzed on a workstation using region-of-interest techniques. Apparent diffusion values recorded in normal marrow were compared with values recorded in abnormal posttraumatic bone marrow (square centimeters per second).

RESULTS

Normal bone marrow identified in 35 patients showed minimal diffusion, with a mean value of 0.15x10(-5) cm2/sec. Bone marrow in 15 patients sustaining direct traumatic injury (21 bone bruises) showed markedly increased diffusion, with a mean value of 0.8x10(-5) cm2/sec (range, 0.4-1.3 cm2/sec).

CONCLUSION

Marrow injury after trauma with trabecular damage allows increased movement or diffusion of interstitial water relative to normal marrow. The magnitude of diffusion change appears to reflect the severity of marrow injury.