Antengene to Present Latest Clinical Results from Two Studies in CPI-resistant Solid Tumors at ASCO 2025

Antengene announced positive clinical trial results for two drug candidates, ATG-037 and ATG-008, in checkpoint inhibitor (CPI)-resistant cancers. ATG-037, combined with pembrolizumab, demonstrated a 36.4% overall response rate (ORR) and 100% disease control rate (DCR) in CPI-resistant melanoma patients, and a 22% ORR and 67% DCR in CPI-resistant NSCLC. Additionally, ATG-008, combined with toripalimab, achieved a 22.2% ORR and 85.2% DCR in CPI-resistant cervical cancer patients, suggesting potential efficacy in difficult-to-treat populations.

Analysis

Antengene Corporation has reported encouraging clinical data for two of its oncology drug candidates, ATG-037 and ATG-008, targeting checkpoint inhibitor (CPI)-resistant cancers. In the ongoing STAMINA-01 Phase I/Ib trial, ATG-037, an oral CD73 inhibitor, demonstrated significant clinical activity when combined with MSD's pembrolizumab (KEYTRUDA®). Specifically, in CPI-resistant melanoma patients, the combination achieved a 36.4% overall response rate (ORR) and a 100% disease control rate (DCR), with one patient maintaining a partial response for over two years without safety concerns. For CPI-resistant non-small cell lung cancer (NSCLC) patients, the same combination yielded a 22% ORR and 67% DCR. Across all CPI-resistant patients receiving the combination (n=28), the ORR was 21.4% and DCR was 78.6%. ATG-037's oral administration and its design to overcome the 'hook effect' associated with anti-CD73 antibodies are key differentiators. The safety profile for both monotherapy (56% TRAEs, n=43) and combination therapy (61% TRAEs, n=28) was manageable, with most treatment-related adverse events (TRAEs) being grade 1-2. Separately, in the TORCH-2 Phase I/II trial, ATG-008, an oral dual mTORC1/2 inhibitor, combined with toripalimab, showed an ORR of 22.2% and a DCR of 85.2% in 27 efficacy-evaluable patients with CPI-resistant cervical cancer. Notably, median progression-free survival was 4.2 months and median overall survival reached 21.4 months. While all 30 patients experienced at least one TEAE and 73.3% reported grade ≥3 TRAEs, most were grade 1-2 and no TEAEs led to death. These results underscore the potential of both ATG-037 and ATG-008 to address high unmet needs in difficult-to-treat, CPI-resistant tumor types, bolstering Antengene's R&D pipeline.

Key Decisions for Investors

• Investors should view these positive interim results for ATG-037 and ATG-008 as potentially de-risking events for Antengene's pipeline, particularly given the high unmet need in checkpoint inhibitor-resistant cancers.
• Monitor upcoming data readouts and the progression of STAMINA-01 and TORCH-2 trials into later stages, as successful advancement could significantly enhance Antengene's valuation.
• Consider the strategic implications of Antengene's focus on oral formulations like ATG-037, which offer convenience and potential advantages over intravenous treatments, and its collaboration with major pharmaceutical companies like MSD for KEYTRUDA.
• Evaluate the balance between the promising efficacy signals and the reported adverse event profiles, particularly the higher rate of grade ≥3 TRAEs with ATG-008, although deemed manageable in the current context.