Tumor cell migration involves proteolytic degradation of the extracellular matrix (ECM), but protease inhibitors only partially inhibit this process, suggesting compensatory mechanisms. In 3D collagen matrices, HT-1080 fibrosarcoma and MDA-MB-231 carcinoma cells exhibit mesenchymal-type migration with integrin and MMP clustering at fiber binding sites. However, near-complete inhibition of proteases leads to a spherical morphology with reduced migration. This suggests a protease-independent amoeboid migration mode, characterized by flexible shape changes, forward propulsion, and constriction rings without matrix degradation. In vivo, HT-1080 cells injected into the mouse dermis showed similar amoeboid migration, indicating a compensatory mechanism for tumor dissemination after proteolysis is blocked. The transition from mesenchymal to amoeboid migration highlights a supramolecular plasticity in cell movement, allowing tumor cells to bypass ECM barriers without proteolysis. This mechanism may serve as an escape strategy for tumor cells in response to protease inhibitor-based therapies. The study reveals that tumor cells can adapt to lose proteolytic capacity by switching to amoeboid movement, which is supported by changes in cytoskeletal structure, integrin distribution, and MMP localization. This finding has implications for understanding tumor cell behavior and developing effective therapeutic strategies.Tumor cell migration involves proteolytic degradation of the extracellular matrix (ECM), but protease inhibitors only partially inhibit this process, suggesting compensatory mechanisms. In 3D collagen matrices, HT-1080 fibrosarcoma and MDA-MB-231 carcinoma cells exhibit mesenchymal-type migration with integrin and MMP clustering at fiber binding sites. However, near-complete inhibition of proteases leads to a spherical morphology with reduced migration. This suggests a protease-independent amoeboid migration mode, characterized by flexible shape changes, forward propulsion, and constriction rings without matrix degradation. In vivo, HT-1080 cells injected into the mouse dermis showed similar amoeboid migration, indicating a compensatory mechanism for tumor dissemination after proteolysis is blocked. The transition from mesenchymal to amoeboid migration highlights a supramolecular plasticity in cell movement, allowing tumor cells to bypass ECM barriers without proteolysis. This mechanism may serve as an escape strategy for tumor cells in response to protease inhibitor-based therapies. The study reveals that tumor cells can adapt to lose proteolytic capacity by switching to amoeboid movement, which is supported by changes in cytoskeletal structure, integrin distribution, and MMP localization. This finding has implications for understanding tumor cell behavior and developing effective therapeutic strategies.