While neoadjuvant pembrolizumab (KEYNOTE-689) is now standard of care for resectable head and neck cancer, it carries a critical risk. During the pre-surgical treatment window, some patients may experience disease progression or toxicity that makes them ineligible for their planned curative surgery.

The CheckMate 9LA regimen provides exceptional benefit to PD-L1 negative and squamous histology NSCLC patients. This is significant because these subgroups often respond poorly to other immunotherapy combinations, with Dr. Carbone noting some trials where the control arm outperformed pembrolizumab in these patients.

The Matterhorn study found that adding the immunotherapy drug Durvalumab to FLOT chemotherapy significantly improved survival in localized gastric cancer. Surprisingly, this benefit extended to patients with low or negative PD-L1 expression, challenging the biomarker's predictive value for immunotherapy efficacy in this perioperative setting.

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.

A leading hypothesis for why adding immunotherapy to chemoradiation failed is that radiation, particularly for central tumors, destroys the very lymphocytes immunotherapy aims to activate. This biological mechanism suggests the radiation essentially canceled out the drug's intended effect.

Successful immunotherapies like anti-PD-1 work by shifting the battlefield's arithmetic. They enhance the efficiency of each T-cell, allowing one cell to destroy five or ten cancer cells instead of three. This turns the fight into a 'numbers game' that the immune system can finally win.

Contrary to the standard 'TKI-first' approach for driver mutations, a study in MET exon 14 skipping NSCLC suggests a different strategy. Patients with high PD-L1 expression appeared to have better outcomes with first-line chemoimmunotherapy, reserving the targeted therapy for later. This challenges the conventional wisdom of prioritizing the driver mutation over immunotherapy biomarkers in this specific subgroup.

Despite major advances in immunotherapy, patient selection remains crude compared to targeted therapies. PD-L1 is still the primary, yet imperfect, biomarker used. Dr. Carbone highlights an urgent need to develop better predictive biomarkers to customize immunotherapy regimens, as is standard for targeted agents.

An expert argues forcefully that the PD-L1 biomarker should be "ditched" in bladder cancer. Citing its repeated failure to predict overall survival benefit across multiple major trials, it is deemed an oversimplified and unreliable tool that leads to both over- and under-treatment of patients.