Top Line: Is it safe to keep biologics on-board during metastases-directed ablative radiation?
The Study: TOaSTT was a prospective international registry enrolling 433 patients who underwent 514 courses of metastases-directed stereotactic radiotherapy (SRT) delivered concurrently (±30 days) with biological therapy, including ICIs (61%), small molecules like TKIs and PARP or CDK4/6-inhibitors (29%), and monoclonal antibodies (10%). About half the treatments were intracranial, reflecting real-world practice across 27 centers. Grade 3+ adverse events were uncommon: 5% acute and 6%, with ≤1% grade 5 events. Importantly, uninterrupted biologics were not associated with increased odds of severe acute or late toxicity. Pausing biologics—done in ~18% of patients, most commonly for TKIs—did not improve safety, but nor did it meaningfully impact survival outcomes. Exploratory analyses across drug classes and anatomic sites failed to reveal any glaring red flags.
TBL: In this large prospective registry, on-board biologics during metastases-directed ablative radiation was generally well tolerated, and routinely holding biologics during radiation doesn’t appear necessary. | Looman, JAMA Netw Open 2025
The Study: TOaSTT was a prospective international registry enrolling 433 patients who underwent 514 courses of metastases-directed stereotactic radiotherapy (SRT) delivered concurrently (±30 days) with biological therapy, including ICIs (61%), small molecules like TKIs and PARP or CDK4/6-inhibitors (29%), and monoclonal antibodies (10%). About half the treatments were intracranial, reflecting real-world practice across 27 centers. Grade 3+ adverse events were uncommon: 5% acute and 6%, with ≤1% grade 5 events. Importantly, uninterrupted biologics were not associated with increased odds of severe acute or late toxicity. Pausing biologics—done in ~18% of patients, most commonly for TKIs—did not improve safety, but nor did it meaningfully impact survival outcomes. Exploratory analyses across drug classes and anatomic sites failed to reveal any glaring red flags.
TBL: In this large prospective registry, on-board biologics during metastases-directed ablative radiation was generally well tolerated, and routinely holding biologics during radiation doesn’t appear necessary. | Looman, JAMA Netw Open 2025