Patel, H. V. | bioRxiv Science

bioRxiv2023

Tipifarnib potentiates the antitumor effects of PI3Kα inhibition in PIK3CA- and HRAS-dysregulated HNSCC via convergent inhibition of mTOR activity

Outcomes for patients with recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) are poor, with median overall survival ranging from 6 to 18 months. For those who progress on standard of care (chemo)immunotherapy, treatment options are limited, necessitating the development of rational therapeutic strategies. Toward this end, we targeted the key HNSCC drivers PI3K-mTOR and HRAS via the combination of tipifarnib, a farnesyltransferase inhibitor, and alpelisib, a PI3K inhibitor, in multiple molecularly defined subsets of HNSCC. We find that tipifarnib synergizes with alpelisib at the level of mTOR in PI3K-or HRAS-dependent HNSCCs, leading to marked cytotoxicity in vitro and tumor regression in vivo. Based on these findings, we have launched the KURRENT-HN trial to evaluate the effectiveness of this combination in PIK3CA-mutant/amplified and/or HRAS-overexpressing R/M HNSCC. Preliminary evidence supports the clinical activity of this molecular biomarker-driven combination therapy. SignificanceBacked by strong mechanistic rationale, the combination of alpelisib and tipifarnib has the potential to benefit >45% of R/M HNSCC patients. By blocking feedback reactivation of mTORC1, tipifarnib may prevent adaptive resistance to additional targeted therapies, thereby enhancing their clinical utility.

cancer biology↗

bioRxiv2021

A competitive activity-based protein profiling platform yields cell wall synthesis inhibitors active against replicating and non-replicating Mycobacterium tuberculosis

The identification and validation of a small molecules targets is a major bottleneck in the discovery process for tuberculosis antibiotics. Activity-based protein profiling (ABPP) is an efficient tool for determining a small molecules targets within complex proteomes. However, how target inhibition relates to biological activity is often left unexplored. Here we studied the effects of 1,2,3-triazole ureas on Mycobacterium tuberculosis (Mtb). After screening ~200 compounds, we focused on two inhibitors active against both exponentially replicating and hypoxia-induced drug-tolerant Mtb that form part of a four-compound structure-activity series. The compound with negligible activity revealed potential false positive targets not addressed in other ABPP studies. Biochemistry, computational docking, and morphological analysis confirmed that active compounds preferentially inhibit serine hydrolases with cell wall and lipid metabolism functions and that disruption of the cell wall underlies biological activity. Our findings showed that ABPP identifies the targets most likely relevant to a compounds antibacterial activity.

microbiology↗