Pathway profiling of a novel SRC inhibitor, AZD0424, in combination with MEK inhibitors for cancer treatment

Abstract

A more comprehensive understanding of how cells respond to drug intervention, the likely immediate signalling responses and how resistance may develop within different microenvironments will help inform treatment regimes. The nonreceptor tyrosine kinase SRC regulates many cellular signalling processes, and pharmacological inhibition has long been a target of cancer drug discovery projects. Here, we describe the in vitro and in vivo characterisation of the small-molecule SRC inhibitor AZD0424. We show that AZD0424 potently inhibits the phosphorylation of tyrosine-419 of SRC (IC50 ~100 nM) in many cancer cell lines; however, inhibition of cell viability, via a G1 cell cycle arrest, was observed only in a subset of cancer cell lines in the low (on target) micromolar range. We profiled the changes in intracellular pathway signalling in cancer cells following exposure to AZD0424 and other targeted therapies using reverse-phase protein array (RPPA) analysis. We demonstrate that SRC is activated in response to treatment of KRAS-mutant colorectal cell lines with MEK inhibitors (trametinib or AZD6244) and that AZD0424 abrogates this. Cell lines treated with trametinib or AZD6244 in combination with AZD0424 had reduced EGFR, FAK and SRC compensatory activation, and cell viability was synergistically inhibited. In vivo, trametinib treatment of mice-bearing HCT116 tumours increased phosphorylation of SRC on Tyr419, and, when combined with AZD0424, inhibition of tumour growth was greater than with trametinib alone. We also demonstrate that drug-induced resistance to trametinib is not re-sensitised by AZD0424 treatment in vitro, likely as a result of multiple compensatory signalling mechanisms; however, inhibition of SRC remains an effective way to block invasion of trametinib-resistant tumour cells. These data imply that SRC inhibition may offer a useful addition to MEK inhibitor combination strategies.

Crosstalk with lung fibroblasts shapes the growth and therapeutic response of mesothelioma cells

“…Some caution is suggested by the toxicity of the combination of saracatinib and vistusertib in our genetically-engineered mouse model. In future experiments, toxicity may be addressed through the dose of each compound, better scheduling or combination with new generation improved SRC inhibitors [99]. Nevertheless, our results show that saracatinib as single agent provides superior activity in this model than the current standard-of-care, extending the medium survival of asbestos-treated animals by 72 days without noticeable toxicity.…”

Combining MEK and SRC inhibitors for treatment of colorectal cancer demonstrate increased efficacy in vitro but not in vivo

“…Among these combinations, we identified classes of PI3K/mTOR, SRC, and receptor tyrosine kinase inhibitors that are broadly synergistic with trametinib in KRAS-mutant cell lines. Importantly, some of these classes were previously identified as synergistic to MEK inhibitors and with our current knowledge of cell signaling pathways, these findings were anticipated; these findings increased our confidence that this method provides relevant information [ 42 – 45 ].…”

“…Researchers have examined the effects of the combination of SRC and MEK inhibitors on other cancer types with activation of the MAPK pathway [ 57 – 59 ]. Initial success of these studies provides a rationale for combining SRC inhibitors with MEK inhibitors in clinical studies [ 45 , 60 , 61 ]. This rationale is also supported by our in vitro studies that identifies dasatinib as a drug that enhances the efficacy of trametinib against KRAS-mutated CRC.…”

KRAS Mutations in Solid Tumors: Characteristics, Current Therapeutic Strategy, and Potential Treatment Exploration

“…Apart from drugs directly targeting KRAS, a number of indirectly targeted therapies targeting its upstream or downstream signaling pathway have also been developed. A study found that AZD0424 (an SRC inhibitor), when combined with MEK inhibitors (such as trametinib), inhibits tumor growth more than MEK inhibitor monotherapy, but does not reverse pre-existing MEK inhibitor resistance [ 78 ]. A study of KRAS G12R-mutant pancreatic cancer patients treated with selumetinib (KOSELUGO™; ARRY-142886, an oral MEK1/2 inhibitor) showed a median PFS of 3.0 months and a median OS of 9 months.…”