GIGO = garbage in, gold out?

In an effort by a team at AstraZeneca, novel PROTAC degraders for 2′-deoxynucleoside 5′-monophosphate N-glycosidase (DNPH1) (an oncology target) were discovered through a Direct-to-Biology (D2B) platform.  They employed two different campaigns, one in which the binding moiety was derived from a DNA-encoded library hit (Campaign #1) and one in which the binding moiety was derived from an HTS hit (Campaign #2).  For the DEL hit, enrichment data helped to inform a region of the molecule where the E3 ligase could be tethered.  They described a set of 238 different E3 ligase ligands that could be attached using amide coupling conditions in a 384-well plate on a 120 nmol scale, with 218 wells showing >30% of desired product.  (Detection was performed using DNPH1 degradation assay with HiBit-tagged SUM149PT cells).  Example 33 illustrates one of the more potent compounds found from this effort.  Next, they conducted an HTS screen and used the HTS hit (Campaign #2) to do the same thing as they did with the DEL hit.  One interesting quote from this part of the effort is highlighted:

 “Previous research indicated that even low-conversion reactions provide valuable assay readouts for identifying active PROTACs”. 

As such, they screened all the wells in this plate using the Hi-Bit assay and followed with a 10-pt DRC.   They reported that a part of the array (120 wells) exhibited nanomolar-range degradation potency (DC₅₀ > 7.0). Additionally, 13% of the array (49 wells) showed degradation levels exceeding 65%.  Out of this mixture, they identified compound 59,  which had a DC₅₀ of 11 nM and D_max of 70% from the crude reaction mixture, despite only 7% product formation. Following resynthesis and purification, the purified sample replicated the findings in the low nM region and high Dmax.