As multiple new drugs like antibody-drug conjugates (ADCs) become available for SCLC, the critical research question will shift from *if* they work to *when* they should be used. Future biomarker strategies must focus on optimizing treatment sequences, considering factors like the drug's target and payload.

In community SCLC care, molecular strategies are not monolithic. Genomic alteration testing (NGS) is ready for immediate use and can identify targets today. In contrast, neuroendocrine subtyping is still investigational and not yet clinically actionable, pending results from research studies.

Genetic tests like DecisionDX for squamous cell carcinoma are evolving from simply predicting recurrence risk to actively informing treatment choices. Ongoing studies are exploring whether these tests can determine a patient's potential benefit from adjuvant radiation therapy, representing a critical step toward personalized medicine.

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.

Unlike novel challenges from bispecifics, upcoming SCLC therapies like antibody-drug conjugates (ADCs) and radiopharmaceuticals will benefit from existing familiarity. Community practices are already comfortable with these drug classes from their use in breast cancer (ADCs) and prostate cancer (radioligands), which should streamline their integration.

The ongoing SWOG PRISM study represents a paradigm shift for small cell lung cancer (SCLC). By analyzing gene expression profiles to identify molecular subtypes during initial therapy, the trial aims to assign patients to different targeted agents. This moves away from the current one-size-fits-all strategy towards a personalized approach based on underlying tumor biology.

The success of perioperative osimertinib means oncologists cannot choose the optimal strategy (targeted therapy vs. chemoimmunotherapy) for resectable lung cancer without first knowing the patient's EGFR, ALK, and PD-L1 status. This elevates biomarker profiling from a metastatic-setting tool to a critical first step in early-stage disease.

The long-standing platinum doublet backbone for frontline SCLC may soon be challenged. The high efficacy of novel agents like antibody-drug conjugates and bispecific antibodies in later lines is prompting trials that consider moving them into the first-line setting, a strategy previously considered "unthinkable."

Despite being "targeted therapies," multiple promising antibody-drug conjugates (ADCs) for small cell lung cancer (SCLC) show no correlation between the target protein's expression level and patient response. This suggests the payload or other factors are the primary drivers of efficacy, complicating biomarker development for patient selection.