Mefuparib Hydrochloride

CVL218, a novel poly ADP‐ribose polymerase (PARP1/2) inhibitor, has strong PARP1/2 selective inhibitory activity and high oral bioavailability. We aimed to assess the safety and tolerability of CVL218 in patients with pretreated advanced solid tumors. Patients in this phase I dose escalation trial received one dose of CVL218 (50, 100, 200, 350, 500, 600, 700, and 850 mg) twice a day. The safety, tolerability, maximum tolerated dose (MTD), dose‐limiting toxicity (DLT), recommended dose, as well as antitumor activity of CVL218 were evaluated. A total of 26 patients were enrolled in this trial. The most common treatment‐related adverse events were vomiting (76.9%), nausea (76.9%), diarrhea (38.5%), proteinuria (23.1%), and lipase increased (23.1%). DLTs occurred in three patients, one out of six in the 700 mg BID group, and two out of five in the 850 mg BID group, so the MTD was set to 700 mg BID. Overall, the disease control rate (DCR) was 70.8%, while the DCR of patients with high‐level doses (≥700 mg BID) and recommended dose (700 mg BID) were both 100%. CVL218 was generally well tolerated and safe. It showed potential antitumor activity in patients treated with the recommended dose.

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) targeting PARP1 and PARP2 have revolutionized cancer therapy by selectively killing cancer cells with defective DNA repair. However, achieving PARP1 or PARP2-selective inhibitors is difficult due to structural homology. Selectivity profiling is typically done with purified proteins, but these lack the complexity of intracellular environments and could therefore be inaccurate. Here, we duplex PARP1 L713F-GFP and PARP2 L269A-mCherry cellular target engagement by accumulation of mutant (CeTEAM) drug biosensors to systematically characterize binding and cell cycle alterations of 27 PARPi. Our results reveal that most PARPi are equipotent for both PARPs, including the next-generation drug, senaparib. However, benzimidazole carboxamide (niraparib) derivatives demonstrated PARP1-selective tendencies, while phthalazinones (olaparib) favored PARP2. AZD5305, a reported PARP1-selective inhibitor with characteristics of both series, was the exception and appears ∼1600-fold more potent toward PARP1. In agreement with current understanding, we see that trapping-associated S/G2-phase transitions positively correlate with PARP1/2 binding potency, while some potent binders, such as veliparib, did not - likely reflecting their allosteric influence on DNA retention. We also assessed the effect of the PARP1/2 active site component, histone PARylation factor 1, on intracellular PARPi binding and see that its depletion elicits slight deviations in apparent binding potency, while contributing additively to trapping-like phenotypes. The PARP1/2 CeTEAM platform thus provides a structural roadmap for the development of selective PARPi and should facilitate the discovery of targeted therapies. Furthermore, our results highlight that multiplexing CeTEAM biosensors and layered genetic perturbations can systematically profile determinants of intracellular drug selectivity.