International Research Journal of Oncology

Cancer treatment has undergone a profound transformation over the past two decades, evolving from non-specific cytotoxic chemotherapy toward precision-based targeted therapies and immunotherapeutic strategies. Advances in molecular oncology have enabled the identification of oncogenic drivers, aberrant signaling pathways, and immune regulatory mechanisms that govern tumor initiation, progression, and therapeutic resistance. Targeted therapies selectively inhibit key molecular alterations, such as receptor tyrosine kinases, intracellular kinases, and cell-cycle regulators, resulting in improved efficacy and reduced systemic toxicity compared with conventional chemotherapy. Concurrently, immunotherapy has revolutionized cancer management by restoring antitumor immune surveillance through immune checkpoint inhibition, adoptive cell therapies, cancer vaccines, and cytokine-based approaches.

Despite significant clinical success, both targeted therapy and immunotherapy face critical challenges, including intrinsic and acquired resistance, limited durability of responses, immune evasion, and treatment-related toxicities. Tumor heterogeneity, adaptive signaling rewiring, and the immunosuppressive tumor microenvironment substantially contribute to therapeutic failure. Emerging evidence underscores the pivotal role of immune cell infiltration, metabolic reprogramming, and immune checkpoint pathways in shaping treatment outcomes. Biomarkers such as tumor mutational burden, mismatch repair deficiency, PD-L1 expression, and gene expression signatures have shown promise in patient stratification and therapeutic decision-making, although their predictive accuracy remains imperfect.

This narrative review comprehensively examines the molecular basis and clinical applications of targeted and immunotherapeutic approaches across multiple cancer types. A structured literature search was conducted using databases including PubMed, Scopus, and Google Scholar, focusing on peer-reviewed articles published primarily between 2010 and 2024, with emphasis on recent clinical trials and translational studies. Key mechanisms of action, landmark clinical evidence, approved agents, resistance mechanisms, and immune-related adverse events are discussed. Special emphasis is placed on rational combination strategies integrating targeted therapy with immunotherapy to enhance antitumor efficacy, overcome resistance, and improve long-term clinical outcomes. Additionally, emerging therapeutic strategies, novel biomarkers, and future directions in precision oncology are highlighted. Overall, the integration of targeted therapy and immunotherapy represents a paradigm shift in oncology, offering the potential for more durable, effective, and individualized cancer treatment.