Targeting a Rare and Aggressive Cancer

On 09 December 2024, Roche released updated data from its ongoing Phase II trial of atezolizumab in patients with RET-altered thyroid cancer, a rare and aggressive form of the disease. The trial showed a 35% overall response rate (ORR) and durable disease control in patients who had progressed on prior kinase inhibitors.

RET mutations are found in a subset of medullary and papillary thyroid cancers and are associated with poor prognosis. While targeted kinase inhibitors like selpercatinib and pralsetinib have shown efficacy, resistance often develops, leaving patients with few options.

Trial Highlights

The study enrolled 72 patients with advanced RET-mutant thyroid cancer. Participants received atezolizumab monotherapy every three weeks. Key findings include:

• 35% ORR, with 12% achieving complete response
• Median progression-free survival (PFS): 8.7 months
• Durable responses observed in both medullary and papillary subtypes
• Safety profile consistent with prior PD-L1 trials, with manageable immune-related adverse events

These results suggest that immune checkpoint inhibition may offer benefit even in genetically driven cancers traditionally considered less immunogenic.

Expanding the Immunotherapy Landscape

The success of atezolizumab in this niche indication reflects a broader trend in 2024 toward precision immunotherapy, where checkpoint inhibitors are paired with genomic profiling to identify responsive subgroups.

Roche plans to initiate a confirmatory Phase III trial in early 2025 and is exploring combination strategies with RET inhibitors and tumour vaccines.

If approved, atezolizumab could become the first immunotherapy indicated for RET-altered thyroid cancer, expanding options for a patient population with high unmet need.