Pyrotinib combined with CDK4/6 inhibitor in HER2-positive metastatic gastric cancer: A promising strategy from AVATAR mouse to patients

Abstract

Background: Pyrotinib was well tolerated but its efficacy was unsatisfactory in patients with HER2-positive gastric cancer (GC) (NCT02378389). This study was to optimize the efficacy of pyrotinib.

Methods: Human GC cell lines and AVATAR mice were used to explore the refractory mechanisms of pyrotinib. A pyrotinib-combined strategy was proposed, which was validated in preclinical AVATAR mouse and in clinical patients enrolled in a phase I clinical trial (NCT03480256).

Results: Dysregulation of CCND1-CDK4/6-Rb axis might be the key to pyrotinib refractory. The strategy of pyrotinib combined with a CDK4/6 inhibitor SHR6390 was proposed and validated in preclinical AVATAR mouse, which was successfully verified in clinical patients. For five patients treated with pyrotinib plus SHR6390 who had available response evaluation, the best response was partial response in three patients, stable disease in one patient, and progressive disease in one patient. The progression-free survival times were 120, 200, 532, 109, and 57 days, respectively.

Conclusions: This translational study suggests that pyrotinib combined with SHR6390 may serve as a promising strategy for patients with HER2-positive GC.

Trial registration: The ClinicalTrials.gov identifiers are NCT02378389 (https://ichgcp.net/clinical-trials-registry/NCT02378389, registered in 11 February 2015) and NCT03480256 (https://ichgcp.net/clinical-trials-registry/NCT03480256, registered in 8 March 2018).

Keywords: CDK inhibitor; pyrotinib; refractory mechanisms.

Conflict of interest statement

Jianjun Zou and Xiaoyu Zhu are employees from Jiangsu Hengrui Medicine Co, Ltd. All other authors have no conflict of interest.

© 2020 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.

Figures

FIGURE 1

Pyrotinib exerts selective antitumor activity in GC AVATAR models. A, Antitumor activity of pyrotinib in 10 GC AVATAR models with different expression of HER2 and EGFR (×200 magnification; scale bar represents 100 µm). Data are presented as mean ± SEM (n = five mice per group). B, The efficacy of pyrotinib in 10 AVATAR models with different molecular features of HER2 and EGFR IHC, immunohistochemistry; FISH, fluorescence in situ hybridization; TGI, tumor growth inhibition.

FIGURE 2

The establishment and characteristics of the pyrotinib‐refractory AVATAR model. A, The process of generating a pyrotinib‐refractory AVATAR model (019R). B, H&E staining and immunohistochemical staining for Ki‐67 in 019P, 019S, and 019R (×100 magnification; scale bar represents 100 µm). C, The Pearson correlation between 019P, 019S, and 019R by transcriptome sequencing

FIGURE 3

CDK4/6 inhibitor SHR6390 sensitizes pyrotinib in pyrotinib refractory AVATAR model. A, Differentially expressed genes (DEGs) in the 019S and 019R detected by RNA sequencing. Green, Padj < .005 and log2 (fold change) < –1; Red, Padj < .005 and log2 (fold change) > 1. B, Quantitative real‐time PCR of CCND1, CDK4, and CDK6 in 019P and 019R. Data are presented as mean ± SD of three independent experiments. C and D, Expression and quantification of critical molecules in the ErbB family and cell‐cycle signaling pathway in 019P, 019S, and 019R. E, The efficacy of pyrotinib, SHR6390, and the combination therapy in 019R. Data are presented as mean ± SD (n = 5 mice per group). F and G, Expression and quantification of critical molecules in the ErbB family and cell cycle signaling pathway in 019R. *P < .05, **P < .01, and ***P < .001 according to repeated measures ANOVAs

FIGURE 4

The clinical responses of three HER2‐positive GC patients treated by pyrotinib combined with SHR6390. A, CT scans of tumor metastases in lung, liver, and hepatic hilar lymph nodes during four cycles of combination treatment in patient 1. C, CT scans of tumor metastases in lung, axillary, and supraclavicular lymph nodes during six cycles of combination treatment in patient 2. E, CT scans of tumor metastases in lung and retroperitoneal lymph nodes during four cycles of combination treatment in patient 3. B, D, and F, The dynamic change of CEA, CA199, CA72.4, and CA125 during combination treatment in patient 1, 2, and 3

FIGURE 5

The clinical responses of the other two HER2‐positive GC patients treated by pyrotinib combined with SHR6390. A, CT scans of tumor metastases in liver, left adrenal gland, and perigastric lymph nodes during three cycles of combination treatment in patient 4. C, CT scans of tumor metastases in liver during two cycles of combination treatment in patient 5. B and D, The dynamic change of CEA, CA199, CA72.4, and CA125 during combination treatment in patient 4 and 5. E, Treatment response of each patient after combination treatment and the duration of response. Patient number are shown to the left of the Y‐axis PR, partial response; SD, stable disease; PD, progressive disease. PFS, progression‐free survival.