State-Space Modulation for Cancer Therapy

Persistent therapeutic variability remains a central challenge in cancer therapy. Contemporary precision oncology has addressed this problem primarily through molecular targeting and patient stratification. Although these approaches have substantially improved therapeutic prediction and patient selection, they remain fundamentally limited in their ability to resolve therapeutic variability, to overcome resistance, and to convert nonresponders to responders.Based on a recently proposed state-space and trajectory-evolution framework for cancer therapy, which emphasizes therapeutic trajectory evolution as the central determinant of outcome, I extend this formulation by introducing a control-oriented extension termed state-space modulation, aimed at modulating state-space organization to regulate trajectory evolution and thereby establish a unified and extensible theoretical structure for cancer therapy. In that formulation, therapeutic outcomes are interpreted not as direct consequences of therapeutic inputs, but as emergent consequences of the therapeutic trajectory evolution initiated by those inputs in the accessible state-space organization. State-space organization refers to the global organization of the tumor–host system arising from biological and physicochemical variables and the composition, relationships, interactions, and constraints among them. Because therapeutic trajectory evolution occurs within and is constrained by this state-space organization, identical therapeutic inputs can generate different trajectory evolution under different state-space organizations, ultimately producing different therapeutic outcomes, including therapeutic response and nonresponse. Under this perspective, therapeutic variability, sensitivity, and resistance emerge as manifestations of the therapeutic trajectory evolution. Since therapeutic variability, sensitivity, and resistance arise from differences in state-space organization, modification of state-space organization represents a rational approach for therapeutic control. State-space modulation is defined as the intentional modification of tumor–host state-space organization to redirect therapeutic trajectory evolution toward more favorable therapeutic outcomes. To achieve this objective, state-space modulation operates through state-space modulating operators, which act primarily through system-level reorganization of the conditions under which therapeutic trajectory evolution occurs. Such reorganization could be achieved through modulation of fundamental organizing variables that serve as modulating interfaces for global state-space modification. Among currently identifiable candidates, pH, oxygen availability, and temperature appear particularly important because of their capacity to induce coordinated changes across multiple biological dimensions. Our previous experimental and clinical studies demonstrate that bicarbonate-mediated pH modulation in hepatocellular carcinoma markedly increases the therapeutic efficacy of TACE and anti-PD-1 therapy and support the state-space modulation concept. In summary, state-space modulation extends therapeutic intervention into a new dimension, providing a conceptual framework that complements precision oncology by rational modification of tumor–host state-space organization. This perspective may guide the development of future therapeutic strategies aimed at improving efficacy, reducing therapeutic variability, converting nonresponders to responders, overcoming resistance, and promoting convergence toward optimal clinical outcomes.