Martha Ingola (Wuppertal / DE), Therese Eriksson Faelker (Wuppertal / DE), Stefanie Zimmermann (Wuppertal / DE), Clara Lemos (Cambridge, MA / US), Philipp Cromm (Wuppertal / DE), Clemens-Jeremias von Buehler (Wuppertal / DE)
Androgen receptor (AR) degraders have emerged as promising therapeutic agents for the treatment of metastatic castration resistant prostate cancer. AR degraders are designed to induce the degradation of the AR protein, which plays a critical role in the growth and progression of prostate cancer. Compared to classical small molecules, novel modalities such as targeted protein degraders (TPD) provide several advantages, offering a potential strategy to overcome resistance to traditional anti-androgen therapies. However, the development and optimization of AR degraders are still in the early stages, and due to its specific mode of action they present unique considerations for safety assessment.
The specificity and selectivity of AR degraders especially needs to be thoroughly evaluated to minimize off-target effects. Off-target liabilities can lead to undesired biological effects and potential adverse effects. Treatment effects were investigated in vitro across cell lines and in vivo using dogs following repeated intravenous infusions to overcome limited oral bioavailability. From these studies both on- and off-target cell and tissue proteomics approaches were established. For the analysis of on-target effects, samples from prostate were collected for tissue proteomics. In addition, 13 different tissue types were collected, including heart, lung, liver, muscle, kidney and brain, to analyze potential off-target effects, especially off-target degradation, using tissue proteomics. The various samples were lysed and the protein extracts digested using the Preomics iST kit in an automated manner using a Hamilton"s StarV automated liquid handling robot. The peptides were separated using a nano ultra-high-performance liquid chromatography (UHPLC) coupled to an Orbitrap mass spectrometry (Orbitrap-MS). The data was acquired in a data-independent acquisition (DIA) manner and data analysis was performed using Spectronaut.
In summary, the utilization of proteomics offers valuable insights into potential off-target effects of the novel modalities mentioned above, thereby contributing to their preclinical risk mitigation and potential clinical application. Furthermore, ongoing investigation and innovation in this field are essential to fully leverage the therapeutic potential of degraders and to advance personalized treatment strategies for several cancers.