Insights into the dose-response relationship of radioembolization with resin yttrium-90 microspheres

Sorry if this has been posted,
http://jnm.snmjournals.org/content/early/2016/02/22/jnumed.115.166942.abstract

I checked back but there have been so many posts on SRX, I may have missed it.

It again refers to the pre treatment selection challenges, and I would concur that it is a challenge. I have to believe that with over 10 years of increasing sales, and in vast improvements in scanning technology, the pt selection is somewhat more targeted than when the SIRFLOX trial started.

I may have my rose coloured speccies on, but my logical conclusion (bias) is that the two later trials should have had better targeting and thus more likely to produce better results that SIRFLOX. We will see, unfortunately another 18 months to find out.
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1. For correspondence or reprints contact: Andor van den Hoven, University Medical Center Utrecht, P.O. Box 85500, H.P. E.01.132, Heidelberglaan 100, Utrecht 3508 GA, Netherlands. E-mail: [email protected]

Abstract

Randomized controlled trials are investigating the benefit of hepatic radioembolization added to systemic therapy in the first/second-line treatment of patients with colorectal liver metastases (CRLM). Remarkably, administered activity may still be suboptimal, because a dose-response relationship has not been defined. The purpose of this study was to characterize the relationship between tumor absorbed dose and response after ⁹⁰Y-radioembolization treatment for CRLM. Methods: 30 patients with unresectable chemorefractory CRLM were treated with resin ⁹⁰Y-microspheres in a prospective phase II clinical trial. Tumor absorbed dose was quantified on ⁹⁰Y-PET. Metabolic tumor activity, defined as tumor lesion glycolysis (TLG*) on ¹⁸F-FDG-PET, was measured at baseline and 1 month posttreatment. The relationship between tumor absorbed dose and posttreatment metabolic activity was assessed per metastasis, with a linear mixed effects regression model. Results: 133 treated metastases were identified. Mean tumor absorbed dose was 51 ± 28 Gy (range 7 – 174 Gy). A 50% reduction in TLG* was achieved in 46% of metastases, and in 11/30 (37%) patients for the sum of metastases. The latter was associated with prolonged median overall survival (11.6 vs. 6.6 months, P = 0.02). A strong, and statistically significant dose-response relationship was found (P < 0.001). The dose-effect depended on baseline TLG* (P < 0.01). Effective tumor absorbed dose was conservatively estimated at a minimum of 40 – 60 Gy. Conclusion: A strong dose-response relationship exists for the treatment of CRLM with resin microspheres ⁹⁰Y-radioembolization. Treatment efficacy is however still limited, because the currently used pretreatment activity calculation methods curb potentially achievable tumor absorbed dose values. A more personalized approach to radioembolization is required before concluding on its clinical potential.