Abstract 3071: Repotrectinib demonstrates promising activities in ROS1 wild-type and solvent-front mutant lung cancer patients-derived preclinical models

The ROS1-rearranged non-small-cell lung cancer (NSCLC) is currently treated with ALK/ROS1 tyrosine kinase inhibitor (TKI) crizotinib as a first-line agent. However, resistance invariably develops and subsequent therapeutic option for overcoming them is limited. Therefore, we investigated the antitumor activity of several ROS1-TKIs in ROS1-positive patient-derived preclinical models.

In this study, we established 6 patient-derived cells (PDCs) from patients with different types of ROS1 fusion partners as follows: treatment-naïve (YU1078, YU1082 and YU1083), crizotinib-resistant G2032R (YU1079) and crizotinib- or entrectinib- primary resistant (YU1081 and YU1085). Sanger sequencing and whole-exome sequencing were then conducted to determine the characteristics. The in vitro and in vivo antitumor activities of ROS1-TKIs in these PDCs were evaluated by comparing the survival, expression assay, duration of tumor re-emergence and ability to penetrate the blood-brain barrier (BBB).

Repotrectinib potently inhibited cell proliferation and ROS1-downstream signaling pathways in YU1078 (CD74-ROS1). In YU1078-derived xenograft models, repotrectinib induced the marked tumor regression and delayed the duration of tumor re-emergence following drug withdrawal compared with crizotinib and entrectinib. Interestingly, both YU1081 (TPM3-ROS1) and YU1082 (SLC34A2-ROS1) with cross primary resistance to other clinically available ROS1-TKIs exhibited high sensitivity to repotrectinib in the concentration range of 100~200 nM. Immunoblot analysis demonstrated that repotrectinib completely suppressed the phosphorylation of ROS1 and STAT3. Notably, repotrectinib showed the selective and highly potency in vitro and in vivo against solvent-front mutant G2032R conferring crizotinib resistance. In G2032R-mutant xenograft models, the response of repotrectinib was still maintained until the end of the experiment (120 days) after drug withdrawal, but loratinib- or cabozantinib-treated tumors rapidly re-emerged. Moreover, repotrectinib induced profound tumor regression in brain metastasis model with excellent brain/plasma and tumor/brain area under the concentration-time curve value. As clinical proof of concept, the potent systemic and intracranial activity of ropotrectinib has been observed in patients who had progressed on prior TKIs or TKI-naïve patients, who were enrolled on-going phase 1/2 clinical trial (NCT03093116).

Our finding indicated a superior antitumor activity of repotrectinib in both wild-type and mutant ROS1 fusion, providing a rationale that repotrectinib may be an effective subsequent or upfront treatment option for patients with ROS1-positive NSCLC who have relapsed on the available TKIs as well as TKI naïve, including patients with progressive CNS metastases.

Citation Format: Dong Hwi Kim, Seok-Young Kim, Hyeong Seok Joo, You Won Lee, Han Na Kang, Min Hee Hong, Hye Ryun Kim, Byoung Chul Cho, Miran Yun. Repotrectinib demonstrates promising activities in ROS1 wild-type and solvent-front mutant lung cancer patients-derived preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3071.

Co-clinical trials demonstrate predictive biomarkers for dovitinib, an FGFR inhibitor, in lung squamous cell carcinoma

Background

We conducted co-clinical trials in patient-derived xenograft (PDX) models to identify predictive biomarkers for the multikinase inhibitor dovitinib in lung squamous cell carcinoma (LSCC).

Methods

The PDX01-02 were established from LSCC patients enrolled in the phase II trial of dovitinib (NCT01861197) and PDX03-05 were established from LSCC patients receiving surgery. These five PDX tumors were subjected to in vivo test of dovitinib efficacy, whole exome sequencing and gene expression profiling.

Results

The PDX tumors recapitulate histopathological properties and maintain genomic characteristics of originating tumors. Concordant with clinical outcomes of the trial enrolled-LSCC patients, dovitinib produced substantial tumor regression in PDX-01 and PDX-05, whereas it resulted in tumor progression in PDX-02. PDX-03 and -04 also displayed poor antitumor efficacy to dovitinib. Mutational and genome-wide copy number profiles revealed no correlation between genomic alterations of FGFR1-3 and sensitivity to dovitinib. Of note, gene expression profiles revealed differentially expressed genes including FGF3 and FGF19 between PDX-01 and 05 and PDX-02-04. Pathway analysis identified two FGFR signaling-related gene sets, FGFR ligand binding/activation and SHC-mediated cascade pathway were substantially up-regulated in PDX-01 and 05, compared with PDX-02-04. The comparison of gene expression profiles between dovitinib-sensitive versus -resistant lung cancer cell lines in the Cancer Cell Line Encyclopedia database also found that transcriptional activation of 18 key signaling components in FGFR pathways can predict the sensitivity to dovitinib both in cell lines and PDX tumors. These results highlight FGFR pathway activation as a key molecular determinant for sensitivity to dovitinib.

Conclusions

FGFR gene expression signatures are predictors for the response to dovitinib in LSCC.

Activation of the Met kinase confers acquired drug resistance in FGFR-targeted lung cancer therapy

Aberrant fibroblast growth factor receptor (FGFR) activation/expression is a common feature in lung cancer (LC). In this study, we evaluated the antitumor activity of and the mechanisms underlying acquired resistance to two potent selective FGFR inhibitors, AZD4547 and BAY116387, in LC cell lines. The antitumor activity of AZD4547 and BAY1163877 was screened in 24 LC cell lines, including 5 with FGFR1 amplification. Two cell lines containing FGFR1 amplifications, H1581 and DMS114, were sensitive to FGFR inhibitors (IC50<250 nm). Clones of FGFR1-amplified H1581 cells resistant to AZD4547 or BAY116387 (H1581AR and H1581BR cells, respectively) were established. Receptor tyrosine kinase (RTK) array and immunoblotting analyses showed strong overexpression and activation of Met in H1581AR/BR cells, compared with that in the parental cells. Gene set enrichment analysis against the Kyoto Encyclopedia of Genes and Genomes (KEGG) database showed that cytokine-cytokine receptor interaction pathways were significantly enriched in H1581AR/BR cells, with Met contributing significantly to the core enrichment. Genomic DNA quantitative PCR and fluorescent in situ hybridization analyses showed MET amplification in H1581AR, but not in H1581BR, cells. Met amplification drives acquired resistance to AZD4547 in H1581AR cells by activating ErbB3. Combination treatment with FGFR inhibitors and an anaplastic lymphoma kinase (ALK)/Met inhibitor, crizotinib, or Met-specific short interfering RNA (siRNA) synergistically inhibited cell proliferation in both H1581AR and H1581BR cells. Conversely, ectopic expression of Met in H1581 cells conferred resistance to AZD4547 and BAY1163877. Acquired resistance to FGFR inhibitors not only altered cellular morphology, but also promoted migration and invasion of resistant clones, in part by inducing epithelial-to-mesenchymal transition. Taken together, our data suggest that Met activation is sufficient to bypass dependency on FGFR signaling. Concurrent inhibition of the Met and FGFR pathways may have synergistic clinical benefits when targeting FGFR-dependent LC.

Structure-activity relationship of lysophosphatidylcholines in HL-60 human leukemia cells

AIM

To explore the structure-activity relationship of lysophosphatidylcholine (LPC) and lysolipid molecules from a marine sponge and ladybirds.

METHODS

We tested three synthetic LPCs and four natural lysolipids on Ca2+ mobilization in HL-60 human leukemia cells.

RESULTS

We observed lysolipid-mediated Ca2+ mobilization. The activity was the same in both ester- and ether-linked lysolipids, and introduction of a double bond or methoxy group on the alkyl chain did not significantly modulate the activity. However, replacement of trimethylammonium moiety in the choline structure with ammonium moiety reduced the activity. Furthermore, change of the alkyl chain length influenced the Ca2+ response.

CONCLUSION

LPC-induced Ca2+ mobilization might be dependent on the length of alkyl chain and the presence of choline moiety in HL-60 leukemia cells.