Stereotactic Radiotherapy Delays Treatment Switch in Those with Oligoprogression

Oligoprogression occurs when a small number of metastases progress on systemic therapy whereas other tumors remain stable or in response. Stereotactic radiotherapy (SRT) has been increasingly used as a strategy for delaying the need to switch systemic therapy in the setting of oligoprogression. It is believed that delaying the switch to another systemic therapy may benefit patients, particularly those who have few treatment options remaining or who are tolerating their current regimen well.¹

In this prospective phase 2 study, patients with advanced renal-cell carcinoma (RCC) who had oligoprogression while receiving a first- or second-line tyrosine kinase inhibitor (TKI) were enrolled. Oligoprogression was defined as radiographic progression of ≤5 metastatic lesions after stable disease or response to ≥3 months of TKI therapy. Patients received SRT to the oligoprogressive tumors; during SRT and for 1 week following, TKI therapy was temporarily paused.¹

A total of 37 patients and 57 oligoprogressive lesions received SRT. Most patients had disease progression on sunitinib; 2 patients had disease progression on pazopanib. TKI therapy was administered for a median of 18.6 months before oligoprogression and enrollment.¹

After a median follow-up of 11.8 months, 2 patients had local failure in SRT-treated lesions, for a 1-year local control rate of 93% (95% confidence interval [CI], 71%-98%). An additional 21 patients had disease progression at nonirradiated sites. Median progression-free survival after irradiation was 9.3 months (95% CI, 7.5-15.7 months), and overall survival at 1 year was 92%.¹

At the 1-year mark, 47% of patients had changed systemic therapy. The median time to a change in systemic therapy was 12.6 months (95% CI, 9.6-17.4 months). An exploratory analysis showed that patients with a longer duration of TKI therapy before SRT had numerically improved progression-free survival (hazard ratio, 0.97; 95% CI, 0.94-1.0; P = .05). The median progression-free survival for patients in the top half of previous TKI duration was longer than for those in the bottom half of previous TKI duration (15.3 vs 7.5 months, respectively).¹

SRT was associated with generally mild adverse events. No grade ≥3 acute or late adverse events were reported. The most common adverse events were fatigue (19%), nausea/vomiting (16%), dyspnea or cough (14%), dyspnea or pneumonitis (11%), and bone/chest wall pain (11%).¹

The researchers concluded that SRT administered at oligoprogressive sites for patients with advanced RCC receiving TKIs resulted in favorable tolerability and delayed the need for a switch to a new systemic therapy.¹ Whether this approach of SRT or immediately changing systemic therapy is superior is unknown.

Reference

1. Cheung P, Patel S, North SA, et al. Stereotactic radiotherapy for oligoprogression in metastatic renal cell cancer patients receiving tyrosine kinase inhibitor therapy: a phase 2 prospective multicenter study. Eur Urol. 2021;80:693-700.