HER2 exon 20 insertions in non-small-cell lung cancer are sensitive to the irreversible pan-HER receptor tyrosine kinase inhibitor pyrotinib

Abstract

Background: Effective targeted therapy for non-small-cell lung cancer (NSCLC) patients with human epidermal growth factor receptor 2 (HER2) mutations remains an unmet need. This study investigated the antitumor effect of an irreversible pan-HER receptor tyrosine kinase inhibitor, pyrotinib.

Patients and methods: Using patient-derived organoids and xenografts established from an HER2-A775_G776YVMA-inserted advanced lung adenocarcinoma patient sample, we investigated the antitumor activity of pyrotinib. Preliminary safety and efficacy of pyrotinib in 15 HER2-mutant NSCLC patients in a phase II clinical trial are also presented.

Results: Pyrotinib showed significant growth inhibition of organoids relative to afatinib in vitro (P = 0.0038). In the PDX model, pyrotinib showed a superior antitumor effect than afatinib (P = 0.0471) and T-DM1 (P = 0.0138). Mice treated with pyrotinib displayed significant tumor burden reduction (mean tumor volume, -52.2%). In contrast, afatinib (25.4%) and T-DM1 (10.9%) showed no obvious reduction. Moreover, pyrotinib showed a robust ability to inhibit pHER2, pERK and pAkt. In the phase II cohort of 15 patients with HER2-mutant NSCLC, pyrotinib 400 mg resulted in a objective response rate of 53.3% and a median progression-free survival of 6.4 months.

Conclusion: Pyrotinib showed activity against NSCLC with HER2 exon 20 mutations in both patient-derived organoids and a PDX model. In the clinical trial, pyrotinib showed promising efficacy.

Clinical trial registration: NCT02535507.

Keywords: HER2 mutations; clinical trial; non-small-cell lung cancer; patient-derived organoids; pyrotinib.

Supplementary Materials

Figure 1

Activity of pyrotinib in HER2-mutant patient-derived organoids. (A, B) 3D organoids in bright field (10 × 10), and H&E and IHC results of representative organoids suggested epithelial origin. (C) Sequencing results of representative organoids showed HER2 A775_G776insYVMA, indicating that the genomic characterization of this patient-derived in vitro models was identical to the parental tumor. (D) Drug response curves of the organoids treated with the dual EGFR/HER2 inhibitors (afatinib and pyrotinib, respectively) showed that the IC₅₀ of afatinib and pyrotinib were 89.1 and 112.5 nM. Cell viability was measured by a CellTiter-Glo (Promega) Luminescent Cell Viability Assay after 72 h of treatment. (E) Cell growth curves of the organoids treated with vehicle (DMSO), afatinib (29 nM^#) and pyrotinib (180 nM^#) showed that compared with afatinib, pyrotinib at plasma concentration inhibited the cell growth more significantly (*P = 0.0038). ^#The concentrations were adopted from the in vivo plasma concentrations of the 2 drugs in previous phase I clinical studies, e.g. (C_afatinib: 21.1 ng/ml)/(MW_afatinib: 718.08 g/mol)×1000 = 29 nM; (C_pyrotinib: 147 ng/ml)/(MW_pyrotinib: 815.22 g/mol)×1000 = 180 nM. (F) Representative images (three repeated well) of the 3D organoids treated with vehicle (DMSO), afatinib (29 nM) and pyrotinib (180 nM) on day 16 after dosing.

Figure 2

In vivo activity of pyrotinib in PDX models. (A) Tumor volume curves of the PDX models treated with vehicle, and different doses of pyrotinib. (B) Tumor volume changes among mice treated with vehicle, and different doses of pyrotinib by 24 days. (C) Body weight changes among mice treated with vehicle, and different doses of pyrotinib. (D) Tumor volume curves of the PDX models treated with vehicle, pyrotinib, afatinib and T-DM1. (E) Tumor volume changes among mice treated with vehicle, and pyrotinib, afatinib and T-DM1 by 24 days. (F) Body weight changes among mice treated with vehicle, pyrotinib, afatinib and T-DM1. (G) Concentrations in plasma and in tumor in different doses of pyrotinib treatment groups were detected on day 24 after administration. The pyrotinib concentration in the tumor of the 80 mg/kg group was not available due to a low volume of tumor tissue after 24 days of pyrotinib treatment. (H) Concentrations in plasma and in tumor of pyrotinib and afatinib treatment groups were detected on day 24 after administration. (I) IHC staining of HER2 and its downstream proteins including ERK and Akt, in vehicle and pyrotinib treatment groups. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.

Figure 3

PK/PD correlation of pyrotinib in PDX model. (A) Concentrations of pyrotinib in plasma and in tumor were detected at 0, 2, 6, 24 h after dosing. Pyrotinib plasma concentrations peaked at ∼2 h after dosing. Concentration of pyrotinib in tumor reached a relative maximum at 6 h, and at the same time, pHER2 was maximally inhibited. (B) Representative images of pHER2 in tumor tissues at 0, 2, 6, 24 h after pyrotinib treatment. (C, D) Western blot analyzed the proteins of HER2 and its downstream proteins including ERK and Akt in mice treated with pyrotinib (80 mg/kg) at 0, 2, 6 h after dosing. Phosphorylation of these proteins was significantly inhibited 6 h after dosing. (E, F) IHC analyzed the proteins of HER2 and its downstream proteins including ERK and Akt in mice treated with pyrotinib (80 mg/kg) at 0, 2, 6 h after dosing. Phosphorylation of these proteins was significantly inhibited 6 h after dosing. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.

Figure 4

HER2-mutant lung cancer patients response to pyrotinib. (A, B) Percent best change from baseline of target lesions and progression-free survival (PFS) plots corresponding to each type of HER2 mutations. *The target lesions of this patient increased by <20% while the nontarget lesions progressed, so we evaluated this as progressive disease. (C) Distribution of HER2 mutations observed in the cohort of 15 patients. (D) Treatment time of 15 patients in this study. Prior treatment: Time from diagnosis of advanced NSCLC or relapse. ⋆, this patient had received one cycle of albumin bound-paclitaxel (100 mg i.v.gtt, D1) during postprogressive pyrotinib treatment. (E) Computed tomography (CT) scan of a 78-year-old patient with HER2-A775_G776YVMA-inserted advanced lung cancer. His lung lesions were significantly reduced after pyrotinib treatment and CT scan showed sustained tumor shrinkage. (F) CT scan of a 53-year-old patient with HER2-A775_G776YVMA-inserted advanced lung cancer. He responded to pyrotinib after disease progression on afatinib.