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Elisa De Stanchina
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MA21 - Non EGFR/MET Targeted Therapies (ID 153)
- Event: WCLC 2019
- Type: Mini Oral Session
- Track: Targeted Therapy
- Presentations: 1
- Now Available
- Moderators:Benjamin Besse, Michael Thomas
- Coordinates: 9/10/2019, 14:30 - 16:00, Vienna (2016)
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MA21.01 - Generation and Characterization of Novel Preclinical Disease Models of NSCLC with NRG1 Rearrangements to Improve Therapy (Now Available) (ID 2811)
14:30 - 16:00 | Author(s): Elisa De Stanchina
- Abstract
- Presentation
Background
Chimeric proteins encoded by NRG1 rearrangements retain the EGF-like domain of NRG1, a HER3 ligand that triggers HER3-HER2 heterodimerization and drives tumor growth. Activating NRG1 fusions have been identified in a variety of cancers including lung, pancreatic, breast, head and neck, etc, and previous work by our group has shown that anti-HER3 antibody (GSK2849330) therapy was effective at inducing a durable response in a NSCLC patient with a CD74/NRG1-fusion. It is possible that targeting both HER2 and HER3 would be more effective than targeting HER3 alone given that HER3-HER2 dimerization is necessary for tumorigenesis induced by NRG1 rearrangements. However, this has not been explored extensively due to a paucity of well-characterized preclinical models of NRG1-driven NSCLC. We aimed to establish patient-derived xenograft (PDX) and cell line models with NRG1-rearrangements to evaluate signaling networks and the role of novel therapies for this recently identified oncogene.
Method
Approximately 30,000 tumor samples were evaluated for the presence of NRG1-fusions by targeted DNA and RNA sequencing (using the MSK-IMPACT and MSK-Fusion panels, respectively). Fresh tumor samples were collected and implanted into immune-compromised mice to generate PDX models and/or used to generate cell lines. Separately, NRG1-fusions were genomically engineered using CRISPR-Cas9 systems or by lentiviral transduction of cDNAs into immortalized human bronchiolar epithelial (HBEC) cells. RT-PCR and Sanger sequencing were used to verify NRG1-fusion mRNA expression, whereas western blot analysis examined fusion protein expression and phosphorylation. Subsequently, cell viability following inhibition of HER2, HER3 and downstream signaling pathways was assessed.
Result
NRG1 fusions were identified in 24 patients (9 NSCLC); and we successfully generated two PDX models with corresponding cell lines from two NSCLC surgical specimens (2/2). One model harbors a CD74/NRG1 fusion whereas the second harbors a SLC3A2/NRG1-fusion. Using CRISPR-Cas9 mediated gene editing, we are introducing NRG1 fusions that were identified in NCSLC (CD74/NRG1, SLC3A2/NRG1, VAMP2/NRG1) into HBEC cells, and have generated a stable cell line with VAMP2/NRG1 fusion to date. In addition, we established a CD74/NRG1-positive model in HBEC cells using lentiviral transduction. Treatment of NRG1-fusion positive cells with small molecule inhibitors of HER2 (afatinib, neratinib, sapitinib) or trastuzumab inhibited growth, induced caspase 3/7 activity and blocked activation of PI3K and ERK signaling. Neratinib was more potent than other small anti-HER2 molecules. The PI3K inhibitor pictilisib inhibited growth of NRG1 fusion-positive cells as a single agent with little effect on non-tumor control cells.
Conclusion
We generated novel NSCLC PDX and cell line models with verified NRG1 chromosomal rearrangements. In vitro studies show that targeting HER2 and PI3K effectively inhibits growth and induces apoptosis. Studies exploring the efficacy of additional agents targeting HER2, HER3 and PI3K alone or in combination using in vivo models are ongoing and results will be presented.
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P1.12 - Small Cell Lung Cancer/NET (ID 179)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Small Cell Lung Cancer/NET
- Presentations: 1
- Moderators:
- Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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P1.12-15 - PET Imaging of [<sup>18</sup>F]PARP Inhibitor as a Pharmacodynamic Biomarker of Talazoparib in Small Cell Lung Cancer PDXs (ID 1794)
09:45 - 18:00 | Author(s): Elisa De Stanchina
- Abstract
Background
Inhibitors of poly-(ADP)-ribose polymerase (PARP) are promising therapeutics for small cell lung cancer (SCLC). We tested whether PARP inhibitor (PARPi) target engagement as measured by a radiolabeled PARP inhibitor ([18F]PARPi) has the potential to predict drug efficacy in vivo.
Method
Tumor growth inhibition during daily talazoparib treatment was evaluated in mice engrafted with SCLC patient-derived xenografts to evaluate talazoparib efficacy at multiple doses. Mice were intravenously injected with [18F]PARPi radiotracer at multiple time points after single doses of oral talazoparib to quantitatively assess the extent to which talazoparib could reduce tumor radiotracer uptake and PET/CT activity.
Result
A dose range of talazoparib with differential therapeutic efficacy was established, with significant delay in time to reach 1000 mm3 for tumors treated with 0.3 mg/kg (p=0.02) but not 0.1 mg/kg talazoparib. On PET/CT with [18F]PARPi tumor was among the tissues with the highest radioactivity per gram (1.37 ± 0.15 %ID/g), significantly higher than surrounding lung (0.24 ± 0.05 %ID/g, p = 0.007), bone (0.27 ± 0.05 %ID/g, p = 0.007), and muscle (0.24 ± 0.15 %ID/g, p < 0.002). A reduction in [18F]PARPi uptake after talazoparib dosing was consistent with talazoparib clearance, with reduction in PET activity attenuating over 24 hours. Talazoparib target engagement, measured by maximum tumor PET uptake, increased in a dose dependent manner (3.9% vs. 2.1% ID/g for 0.1 and 0.3 mg/kg at 3 hours post-talazoparib, p=0.003) and correlated with PARP enzymatic activity among individual tumors as measured by total tumor PAR (p=0.04, R=0.62 at 1 hour post-talazoparib).
Conclusion
[18F]PARPi PET imaging appears to model PARP inhibitor pharmacokinetics, correlates with PARP inhibitor pharmacodynamics as measured by tumor PAR levels, and differs significantly between therapeutic and subtherapeutic doses of talazoparib. PET imaging using [18F]PARPi has the potential to be a powerful tool in treatment monitoring by assessing PARP inhibitor target engagement in real-time.
