Journal
TRANSLATIONAL LUNG CANCER RESEARCH
Volume 10, Issue 11, Pages 4095-+Publisher
AME PUBL CO
DOI: 10.21037/tlcr-21-437
Keywords
Small cell lung cancer (SCLC); lurbinectedin; ATR; SLFN11; replication stress
Categories
Funding
- NIH/NCI [CCSG R50-CA243698, R01-CA207295, U01-CA213273, T32 CA009666, R50-CA243698]
- University of Texas SPORE in Lung Cancer [P5-CA070907]
- IALSC ILCF Fellowship
- ASCO Young Investigator Award
- Khalifa Bin Zayed Al Nahyan Foundation
- Andrew Sabin Family Fellowship
- Abell Hangar Foundation
- LUNGevity Foundation Career Development Award
- Rexanna Foundation for Fighting Lung Cancer
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The study identified SLFN11 as a potential biomarker for predicting sensitivity of SCLC to lurbinectedin, and combination therapy of lurbinectedin with ATR inhibitors may overcome resistance in SCLC cells with low SLFN11 expression.
Background: Lurbinectedin recently received FDA accelerated approval as a second line treatment option for metastatic small cell lung cancer (SCLC). However, there are currently no established biomarkers to predict SCLC sensitivity or resistance to lurbinectedin or preclinical studies to guide rational combinations. Methods: Drug sensitivity was assayed in proliferation assays and xenograft models. Baseline proteomic profiling was performed by reverse-phase protein array. Lurbinectedin-induced changes in intracellular signaling pathways were assayed by Western blot. Results: Among 21 human SCLC cell lines, cytotoxicity was observed following lurbinectedin treatment at a low dose (median IC50 0.46 nM, range, 0.06-1.83 nM). Notably, cell lines with high expression of Schlafen-11 (SLFN11) protein, a promising biomarker of response to other DNA damaging agents (e.g., chemotherapy, PARP inhibitors), were more sensitive to single-agent lurbinectedin (FC =3.2, P=0.005). SLFN11 was validated as a biomarker of sensitivity to lurbinectedin using siRNA knockdown and in xenografts representing SLFN11 high and low SCLC. Replication stress and DNA damage markers (e.g., gamma H2AX, phosphorylated CHK1, phosphorylated RPA32) increased in SCLC cell lines following treatment with lurbinectedin. Lurbinectedin also induced PD-L1 expression via cGAS-STING pathway activation. Finally, the combination of lurbinectedin with the ATR inhibitors ceralasertib and berzosertib showed a greater than additive effect in SLFN11-low models. Conclusions: Together our data confirm the activity of lurbinectedin across a large cohort of SCLC models and identify SLFN11 as a top candidate biomarker for lurbinectedin sensitivity. In SLFN1 1 low SCLC cell lines which are relatively resistance to lurbinectedin, the addition of an ATR inhibitor to lurbinectedin re-sensitized otherwise resistant cells, confirming previous observations that SLFN11 is a master regulator of DNA damage response independent of ATR, and the absence of SLFN11 leads to synthetic lethality with ATR inhibition. This study provides a rationale for lurbinectedin in combination with ATR inhibitors to overcome resistance in SCLC with low SLFN11 expression.
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