Depth of response greater in patients who receive SIR-Spheres Y-90 resin microspheres

According to a recent study, patients with liver tumors achieved greater depth of response when they received chemotherapy plus SIR-Spheres Y-90 resin microspheres compared with chemotherapy alone.

Depth of response (DpR) is a new methodology previously shown to correlate with overall survival and post-progression survival. Volker Heinemann, MD, professor of medical oncology at the Comprehensive Cancer Centre, Ludwig-Maximillian University, Munich, Germany, and colleagues, developed the DpR method in collaboration with other experts treating colorectal cancer. In their analysis, a model is used to measure a patient’s spherical liver tumor volume based on the length of several target liver tumors. These target tumors are selected through a blinded imaging review of the patient’s baseline and radiographic images. DpR is then measured by tracking tumor shrinkage until it reaches its lowest point.

In the current study — called SIRFLOX — Heinemann and colleagues examined 530 patients with recently diagnosed non-resectable colorectal cancer tumors of the liver. Patients who received the combination therapy had a 75% mean reduction in liver tumor burden vs 67.8% for those receiving only chemotherapy (P = .039). Further, patients who received the combination therapy had a two-month longer time to DpR or maximal tumor shrinkage (median 266 vs 206 days; P < .001).

The results of SIR-Spheres Y-90 resin microspheres were most evident in patients with a greater baseline liver tumor burden (>12% of the liver having been replaced by tumor). These patients, who comprised more than half of the study, saw a 20% greater DpR (77.5% vs 57.2%; P = .003) and over three-months longer time to DpR (median 298 vs 196 days; P < .001) compared with those with chemotherapy alone. In addition, median progression-free survival in the liver doubled by competing risk analysis in these patients.

Patients with a smaller liver tumor burden (≤12%) were more than six times more likely to have a complete response or disappearance of all liver tumors following SIR-Spheres Y-90 resin microspheres compared with those who only received chemotherapy (27.2 vs 13.1 months; P = .003).

“The greater depth of response and time to maximal response following SIR-Spheres Y-90 resin microspheres, together with the prolonged PFS in the liver, are very encouraging and increase our anticipation for the survival data we hope to see in 2017,” Heinemann said in a press release.