Yttrium-90 radioembolization for colorectal cancer liver metastases in KRAS wild-type and mutant patients: Clinical and ccfDNA studies

Patients with unresectable, chemo-refractory colorectal cancer liver metastases (CRCLM) have limited local treatment options. We report our institutional experience on the efficacy of resin-based yttrium-90 (⁹⁰Y) radioembolization for the treatment of CRCLM and our findings on associated circulating cell-free DNA (ccfDNA) studies. A total of 58 patients treated with ⁹⁰Y for CRCLM at the Medstar Georgetown University Hospital had a median survival of 6 months [95% confidence interval (CI), 4.55–7.45 months] after treatment, with a 12-month survival rate of 33%. The median survival from treatment stratified by mutational status was longer in the wild-type (WT) as compared to the KRAS mutant patients at 7 vs. 5 months, but did not achieve statistical significance (p=0.059). Median tumor local control duration after ⁹⁰Y treatment was 2 months (95% CI, 0.34–3.66 months) for the entire cohort and was longer in the WT vs. the mutant patients (2 vs. 1 month, respectively, p=0.088). Plasma was prospectively collected from a subset of 9 patients both before and after single lobe treatment, and ccfDNA concentration and fragmentation index (FI) were measured using quantitative PCR and atomic-force microscopy (AFM). In the WT and KRAS mutant patients, DNA FI was reduced from a median of 0.73–0.65 after treatment. A reduction in DNA FI after single lobe treatment was associated with an improved overall survival (p=0.046). Analysis by AFM of paired pre- and post-treatment samples from KRAS mutant and WT patients revealed a larger average decrease in fragment size in the WT patients (p=0.013). ⁹⁰Y radioembolization extends local control for CRCLM, however, KRAS mutant tumors may be more radio-resistant to treatment. Changes in the FI of patients following treatment were noted and may be evaluated in a larger study for relevance as a biomarker of response.

CyberKnife high-dose fractionated stereotactic radiosurgery with tumor tracking: An effective non-surgical treatment alternative for single small peripheral lung tumors

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Background: We report preliminary outcomes using CyberKnife radiosurgery with tumor tracking to treat small (<4 cm) peripheral inoperable stage I lung cancers and single pulmonary metastases. Methods: Enrollment of eligible pts began in July 2004. Prior conventional thoracic irradiation and the incorporation of systemic therapy were permitted. Fiducials (3–5) were placed near tumors under CT guidance. Pts received 45–60 Gy in 3 equal 1–2 hour fractions delivered over a 5–9 day period. Results: The median follow-up period of survivors was 12 months (range = 3–24 months). A total of 24 lesions were treated, 15 clinical stage I lung cancers and 9 single lung metastases. Four patients had prior conventional thoracic radiation (17%) and 6 patients received systemic therapy in conjunction with radiosurgery (25%). Two received systemic doses of platinum based doublet chemotherapy, 3 received gefitinib and 1 received sunitinib. Pneumothorax was a complication of fiducial placement in 7 pts, requiring tube thoracostomy in 4. All pts completed treatment with few acute side effects. No unexpected additional toxicities were noted with systemic therapy except for one pt who developed Grade III radiation pneumonitis while receiving gefitinib. A second pt with Grade III radiation pneumonitis had prior extensive conventional thoracic radiation. All tumors responded to treatment at 3 months as seen by a decrease in gross tumor volume. At 12 months 14 CT scans were evaluable. Four lesions responded completely (33%), 2 exhibited a partial response and the remaining 8 were obscured by radiation fibrosis corresponding to the high-dose irradiated volume (57%). Local progression was seen in only 2 single lung metastases at 10 and 12 months. There have been no regional lymph node failures. Four patients have died, 1 of progressive metastatic disease and 3 of comorbid illnesses. Conclusion: CyberKnife high-dose fractionated stereotactic radiosurgery with tumor tracking is an effective well-tolerated treatment option for small peripheral lung tumors, both primary and metastatic. The integration of systemic therapy appears feasible but needs to be further evaluated in clinical trials.

No significant financial relationships to disclose.

Feasibility of percutaneous transabdominal portosystemic shunt creation

Evaluation of the anatomic feasibility of the percutaneous transabdominal puncture of selected portal and hepatic veins in patients with cirrhosis was performed. This approach would become the framework for an image-guided robot-assisted needle drive mechanism for use in transjugular intrahepatic portosystemic shunt (TIPS) creation. Retrospective analysis of 10 CT and 14 MRI axial abdominal studies was carried out to determine whether single simultaneous transabdominal puncture of portal and hepatic veins was possible. A necessary modification of the TIPS procedure was tested in an ex vivo porcine model under fluoroscopy. Eighteen of 24 patients (75%) had intrahepatic vascular anatomy amenable to a single transabdominal puncture. Successful catheterization of portal and hepatic veins using a modified approach for TIPS was accomplished in two ex vivo porcine livers. A suitable anatomic approach for modified TIPS is present in a majority of patients with cirrhosis. Feasibility of the technique using this anatomic approach was confirmed in two ex vivo porcine models. This study serves as an initial step in a novel technical approach to TIPS using a new anatomic approach for this procedure.

Interaction of osteoblasts with extracellular matrix: effect of mast cell chymase

We studied the effect of mast cell chymase on the interaction between osteoblasts and extracellular matrix. Chymase was purified from mast cell lysate by anion exchange chromatography. Osteoblasts were isolated from rat calvarias by collagenase digestion. Incubation of osteoblasts with mast cell lysate (40-170 micrograms/ml) or purified chymase (8-32 micrograms/ml) resulted in changes in cell-matrix interaction and cell morphology. Osteoblasts treated with chymase also showed a gradual detachment from the artificial substrata and from the biomatrix (collagen-digested rib fragment). A similar effect of mast cell chymase on the osteoblasts was found in vitro on endosteum of an intact parietal bone. Neutral protease inhibitors abolished the effect of both crude and purified enzyme preparations on the cell-matrix interaction. Mast cell chymase had no effect on osteoblast viability. The effect of enzyme on osteoblast proliferation was studied with lower concentrations of enzyme (0.2 micrograms/ml) in order to avoid cell detachment; there was no effect on either the metaphase index or on the number of cells after 5 days of incubation with chymase. Osteoblast attachment and cell spreading on different matrix proteins (fibronectin, vitronectin, extract of noncollagenous matrix proteins from rat bone) were significantly altered by their pretreatment with chymase. Matrix fibronectin of osteoblasts in culture as well as soluble vitronectin and fibronectin were digested by rat mast cell chymase. Our data suggest that mast cells through action of neutral protease chymase may alter molecules in extracellular matrix that are important in osteoblast adhesion, cell spreading, maintenance of cell morphology, and, most likely, cell function.