First-Hit™ – a novel, phenotypic screening approach for the identification of differentiation inducing compounds in TNBC

Purpose:

New therapeutic approaches for the treatment of solid tumours are urgently needed as severe side effects and resistances often arise. However, of the 259 agents approved by the FDA in ten years, only 75 were first-in-class drugs. This undesirable development can be ascribed to the long-term focus on target-based drug discovery approaches. Whereas the contribution of phenotypic screening to the discovery of first-in-class small-molecule drugs exceeds that of target-based approaches. Furthermore, drugs targeting differentiation blocks are supposed to essentially improve current cancer therapy.

Methods:

We developed a cell-based phenotypic high-throughput screening system which allows the identification of potential differentiation inducing agents in solid tumours via the quantification of two innovative differentiation markers. MDA-MB-231 cells were used as a model for early differentiation arrest. Substances with a known differentiation inducing effect were used to verify the innovative markers of FIRST-HIT™ and the robustness of the platform.

Results:

FIRST-HIT™ could successfully discriminate between two HDAC-inhibitors (pan-/vs. class I&II -inhibitor), one methyltransferase-inhibitor and one nucleoside analogue, proofing that the innovative markers of FIRST-HIT™ successfully mirror the cells' differentiation status. Furthermore, FIRST-HIT™ meets the criteria necessary for an appropriate high-throughput screen, e.g. Z-factor and can be carried out from 96 to 1536-well plate-format.

Conclusions:

Our results successfully revealed that FIRST-HIT™ can uniquely identify differentiation inducing compounds in TNBC. Further studies with substances databases will be performed to identify unknown differentiation inducing compounds with potentially new molecular MOA.