When choosing between therapies for dually positive (Claudin+/PD-L1+) gastric cancer, the existence of robust five-year survival data for immunotherapy regimens provides a compelling reason to prioritize it over newer agents like zolbetuximab, which lack such long-term follow-up.

While median survival improvements in advanced HCC are notable, the truly revolutionary impact of immunotherapy is the creation of a long-term survival "tail" on the Kaplan-Meier curve. Clinicians now manage patients for years, a reality that was nonexistent in the pre-IO era.

In the SPOTLIGHT trial, adding zolbituximab to FOLFOX for Claudin-18.2 positive patients improved progression-free and overall survival. However, it did not significantly increase the objective response rate, demonstrating that survival benefit can be decoupled from tumor shrinkage metrics.

A defining characteristic of antibody-drug conjugates is not just their response rate, but their remarkable duration of response. Patients who respond often maintain that response for a significantly longer period than with standard chemotherapy, a benefit likely attributable to the ADC's effect on the tumor microenvironment.

Similar to findings in small cell lung cancer, immunotherapy combinations in advanced ovarian cancer may create a "tail on the curve." Even if median survival benefit is modest, data shows the survival curves remain separated long-term, suggesting a small but significant subset of patients achieves durable survival of 3-5 years.

Immunotherapy antibodies bind to immune cells for weeks or months, a pharmacodynamic (PD) effect far longer than their pharmacokinetic (PK) half-life. This long-lasting binding suggests that minor variations in infusion timing for subsequent doses are unlikely to impact overall outcomes, casting doubt on the study's core hypothesis.

A key emerging characteristic of belzutifan-based therapies is their ability to produce a long-lasting duration of response. This creates a notable "tail of the curve" in survival plots, suggesting belzutifan adds significant durability to combination regimens.

Dr. Carbone argues that traditional metrics like median survival or response rate are less relevant for immunotherapies. The true measure of success is the percentage of patients alive at five or six years—the "tail of the curve"—as this indicates a durable, potentially curative, response.

The progression-free survival (PFS) curves for Belzutifan regimens consistently overlap with controls for 6-8 months before separating. This signature “Belzutifan effect,” seen across multiple trials, suggests the drug provides durable, long-term disease control for a subset of patients rather than immediate, broad efficacy, hinting at a distinct biological mechanism.