April 28, 2025 brought a series of exciting updates from the oncology immunotherapy landscape, particularly for two investigational drugs – botensilimab and balstilimab being studied both as a pair and as individual agents in aggressive cancers. New clinical trial data presented at major meetings in Chicago and Europe illustrated how these therapies are reshaping expectations for patients who typically have few remaining options.

The Phase 2 NEOASIS study made headlines by reporting significant success for botensilimab and balstilimab in the neoadjuvant (pre-operative) setting across a range of solid tumors, including mismatch repair–proficient (pMMR/MSS) and deficient (dMMR/MSI-H) cancers. Among patients with the harder-to-treat pMMR/MSS cancers, 80% experienced pathological responses, with 20% achieving a complete eradication of their tumors before surgery. For those with dMMR/MSI-H tumors, a remarkable 90% saw tumor shrinkage, and 70% had their cancer entirely disappear under the microscope. Triple-negative breast cancer patients enrolled in the same study also posted major response rates, pointing toward the broad applicability of this immunotherapy combination.

The safety profile remained manageable, with no dose-limiting toxicities and no delays to scheduled surgeries, underscoring the practicality of these agents in the real-world setting. Surgeons and oncologists are encouraged by these results, as the ultimate goal for any pre-surgical treatment is to increase the number of patients who can avoid radical procedures and improve overall survival.

Another highlight came from the UNICORN Phase II trial, which confirmed that in locally advanced colon cancer, a single cycle of botensilimab alone did little. In contrast, when combined with balstilimab, the pathological complete response rate (tumor disappearance) soared to 29% in harder-to-treat pMMR tumors and a staggering 93% in dMMR tumors. These results are, to date, among the highest ever reported in this setting, suggesting that the combination could fundamentally change preoperative therapy standards.

In liver cancer, specifically hepatocellular carcinoma (HCC) that had failed standard immunotherapy, early studies of botensilimab plus balstilimab achieved disease control in nearly three-quarters of patients, with median overall survival exceeding a year an accomplishment in this advanced, high-risk group. The treatments were tolerable, with adverse events consistent with prior immunotherapy experiences, reinforcing hopes for wider future use.

Botensilimab and balstilimab are now progressing to larger, phase 3 pivotal trials such as the BATTMAN study for refractory metastatic colorectal cancer, aiming to offer new hope to patients who have exhausted standard chemotherapy regimens. Continued research will focus on identifying biomarkers to better match therapies with patients, maximizing benefit while minimizing risks, and potentially opening a door to non-surgical management for many with solid tumors.

These findings build on a growing wave of clinical evidence that immune system targeting strategies are quickly advancing from experimental to potentially standard of care. For clinicians and patients alike, April 28’s news signals a shift towards more effective and less invasive treatments for some of the most challenging cancers seen in practice.