Targeting AXL and mTOR Pathway Overcomes Primary and Acquired Resistance to WEE1 Inhibition in Small-Cell Lung Cancer.

Purpose: Drugs targeting DNA repair and cell-cycle checkpoints have emerged as promising therapies for small-cell lung cancer (SCLC). Among these, the WEE1 inhibitor AZD1775 has shown clinical activity in a subset of SCLC patients, but resistance is common. Understanding primary and acquired resistance mechanisms will be critical for developing effective WEE1 inhibitor combinations.Experimental Design: AZD1775 sensitivity in SCLC cell lines was correlated with baseline expression level of 200 total or phosphorylated proteins measured by reverse-phase protein array (RPPA) to identify predictive markers of primary resistance. We further established AZD1775 acquired resistance models to identify mechanism of acquired resistance. Combination regimens were tested to overcome primary and acquired resistance to AZD1775 in in vitro and in vivo SCLC models.Results: High-throughput proteomic profiling demonstrate that SCLC models with primary resistance to AZD1775 express high levels of AXL and phosphorylated S6 and that WEE1/AXL or WEE1/mTOR inhibitor combinations overcome resistance in vitro and in vivo Furthermore, AXL, independently and via mTOR, activates the ERK pathway, leading to recruitment and activation of another G2-checkpoint protein, CHK1. AZD1775 acquired resistance models demonstrated upregulation of AXL, pS6, and MET, and resistance was overcome with the addition of AXL (TP0903), dual-AXL/MET (cabozantinib), or mTOR (RAD001) inhibitors.Conclusions: AXL promotes resistance to WEE1 inhibition via downstream mTOR signaling and resulting activation of a parallel DNA damage repair pathway, CHK1. These findings suggest rational combinations to enhance the clinical efficacy of AZD1775, which is currently in clinical trials for SCLC and other malignancies. Clin Cancer Res; 23(20); 6239-53. ©2017 AACR.

Sen T ，Tong P ，Diao L ，Li L ，Fan Y ，Hoff J ，Heymach JV ，Wang J ，Byers LA ... -  《-》

GCN2 is a determinant of the response to WEE1 kinase inhibition in small-cell lung cancer.

Patients with small-cell lung cancer (SCLC) are in dire need of more effective therapeutic options. Frequent disruption of the G1 checkpoint in SCLC cells creates a dependency on the G2/M checkpoint to maintain genomic integrity. Indeed, in pre-clinical models, inhibiting the G2/M checkpoint kinase WEE1 shows promise in inhibiting SCLC growth. However, toxicity and acquired resistance limit the clinical effectiveness of this strategy. Here, using CRISPR-Cas9 knockout screens in vitro and in vivo, we identified multiple factors influencing the response of SCLC cells to the WEE1 kinase inhibitor AZD1775, including the GCN2 kinase and other members of its signaling pathway. Rapid activation of GCN2 upon AZD1775 treatment triggers a stress response in SCLC cells. Pharmacological or genetic activation of the GCN2 pathway enhances cancer cell killing by AZD1775. Thus, activation of the GCN2 pathway represents a promising strategy to increase the efficacy of WEE1 inhibitors in SCLC.

Drainas AP ，Hsu WH ，Dallas AE ，Poltorack CD ，Kim JW ，He A ，Coles GL ，Baron M ，Bassik MC ，Sage J ... -  《Cell Reports》

PAXIP1 Potentiates the Combination of WEE1 Inhibitor AZD1775 and Platinum Agents in Lung Cancer.

The DNA damage response (DDR) involves a complex network of signaling events mediated by modular protein domains such as the BRCA1 C-terminal (BRCT) domain. Thus, proteins that interact with BRCT domains and are a part of the DDR constitute potential targets for sensitization to DNA-damaging chemotherapy agents. We performed a pharmacologic screen to evaluate 17 kinases, identified in a BRCT-mediated interaction network as targets to enhance platinum-based chemotherapy in lung cancer. Inhibition of mitotic kinase WEE1 was found to have the most effective response in combination with platinum compounds in lung cancer cell lines. In the BRCT-mediated interaction network, WEE1 was found in complex with PAXIP1, a protein containing six BRCT domains involved in transcription and in the cellular response to DNA damage. We show that PAXIP1 BRCT domains regulate WEE1-mediated phosphorylation of CDK1. Furthermore, ectopic expression of PAXIP1 promotes enhanced caspase-3-mediated apoptosis in cells treated with WEE1 inhibitor AZD1775 (formerly, MK-1775) and cisplatin compared with cells treated with AZD1775 alone. Cell lines and patient-derived xenograft models expressing both PAXIP1 and WEE1 exhibited synergistic effects of AZD1775 and cisplatin. In summary, PAXIP1 is involved in sensitizing lung cancer cells to the WEE1 inhibitor AZD1775 in combination with platinum-based treatment. We propose that WEE1 and PAXIP1 levels may be used as mechanism-based biomarkers of response when WEE1 inhibitor AZD1775 is combined with DNA-damaging agents. Mol Cancer Ther; 15(7); 1669-81. ©2016 AACR.

Jhuraney A ，Woods NT ，Wright G ，Rix L ，Kinose F ，Kroeger JL ，Remily-Wood E ，Cress WD ，Koomen JM ，Brantley SG ，Gray JE ，Haura EB ，Rix U ，Monteiro AN ... -  《-》

Augmented antitumor activity by olaparib plus AZD1775 in gastric cancer through disrupting DNA damage repair pathways and DNA damage checkpoint.

Lin X ，Chen D ，Zhang C ，Zhang X ，Li Z ，Dong B ，Gao J ，Shen L ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

The Combination of the PARP Inhibitor Olaparib and the WEE1 Inhibitor AZD1775 as a New Therapeutic Option for Small Cell Lung Cancer.

Purpose: Introduced in 1987, platinum-based chemotherapy remains standard of care for small cell lung cancer (SCLC), a most aggressive, recalcitrant tumor. Prominent barriers to progress are paucity of tumor tissue to identify drug targets and patient-relevant models to interrogate novel therapies. Following our development of circulating tumor cell patient-derived explants (CDX) as models that faithfully mirror patient disease, here we exploit CDX to examine new therapeutic options for SCLC.Experimental Design: We investigated the efficacy of the PARP inhibitor olaparib alone or in combination with the WEE1 kinase inhibitor AZD1775 in 10 phenotypically distinct SCLC CDX in vivo and/or ex vivo These CDX represent chemosensitive and chemorefractory disease including the first reported paired CDX generated longitudinally before treatment and upon disease progression.Results: There was a heterogeneous depth and duration of response to olaparib/AZD1775 that diminished when tested at disease progression. However, efficacy of this combination consistently exceeded that of cisplatin/etoposide, with cures in one CDX model. Genomic and protein analyses revealed defects in homologous recombination repair genes and oncogenes that induce replication stress (such as MYC family members), predisposed CDX to combined olaparib/AZD1775 sensitivity, although universal predictors of response were not noted.Conclusions: These preclinical data provide a strong rationale to trial this combination in the clinic informed by prevalent, readily accessed circulating tumor cell-based biomarkers. New therapies will be evaluated in SCLC patients after first-line chemotherapy, and our data suggest that the combination of olaparib/AZD1775 should be used as early as possible and before disease relapse. Clin Cancer Res; 24(20); 5153-64. ©2018 AACR.

Lallo A ，Frese KK ，Morrow CJ ，Sloane R ，Gulati S ，Schenk MW ，Trapani F ，Simms N ，Galvin M ，Brown S ，Hodgkinson CL ，Priest L ，Hughes A ，Lai Z ，Cadogan E ，Khandelwal G ，Simpson KL ，Miller C ，Blackhall F ，O'Connor MJ ，Dive C ... -  《-》