The bispecific antibody Ivanesimab binds to the VEGF dimer, creating a "daisy chain" of antibody-VEGF complexes. This multimerization concentrates the drug in the tumor microenvironment, where VEGF is high, and enhances its ability to bind and block PD-1 more effectively than single-molecule approaches.

Early 4-1BB agonists failed due to severe liver toxicity. Excalipoint's bispecifics solve this by requiring one arm to bind to a tumor before the other activates T-cells. This localizes the immune response, preventing systemic toxicity and reviving a previously failed mechanism for cancer therapy.

With multiple PD-L1/VEGF bispecifics showing similar high efficacy, the ultimate market leader will likely be determined by strategic clinical trial design—including patient selection, endpoint ambition, and generation of robust global data—rather than minor molecular differences between the compounds.

The HARMONY-2 study showed Ivanesimab delivered a median progression-free survival of 11.3 months compared to 5.8 months for Pembrolizumab in PD-L1 positive NSCLC. Analysis confirmed Pembrolizumab performed as expected, suggesting the dual VEGF/PD-1 blockade provides a genuinely superior clinical benefit over PD-1 inhibition alone.

Beyond simply blocking the PD-1/PD-L1 pathway, these bispecifics may form a macromolecular structure with VEGF and PD-L1 in the tumor microenvironment. This structure can cause the cancer cell to internalize the PD-L1 protein, effectively removing it as a target and creating a dual blockade.

After standard immunotherapy biomarkers like PD-L1 and TMB proved ineffective in SCLC, the field shifted to a more direct approach. Novel therapies like the bispecific antibody tarlatumab target surface proteins such as DLL3, physically bridging immune cells to cancer cells without relying on predictive biomarkers.

In the HARMONY A study, Ivanesimab plus chemotherapy significantly improved progression-free survival in EGFR-mutant non-small cell lung cancer patients. This is notable because prior trials showed that adding standard PD-1 inhibitors to chemotherapy was ineffective for this specific patient population.

Bispecific antibodies, which target two antigens like PD-1 and VEGF simultaneously, are viewed as the next major upgrade to standard immunotherapy. Their 'cooperative binding' mechanism is expected to improve efficacy and safety, and early trial data suggest they could replace decade-old checkpoint inhibitors like pembrolizumab as the new standard of care.

Unlike bevacizumab's long 20-day half-life and associated bleeding risks that excluded squamous cell carcinoma patients, new bispecifics have a ~6-day half-life. This results in a similar but less severe toxicity profile, broadening their clinical application to a wider patient population.