Cancer cells have evolved mechanisms to escape the body’s immune defense. Agents that prevent immune escape are attractive targets for the development of new cancer therapies. Scientists led by Prof. Herbert Waldmann and Dr. Slava Ziegler at the Max Planck Institute of Molecular Physiology in Dortmund have now developed a new cell-based test system to identify immunoregulatory modulators. Screening a library of over 150,000 substances revealed several potent substances with unprecedented structure.