ErbB Receptor Tyrosine Kinase Inhibitors Research Articles

Pyrotinib Sensitizes 5-Fluorouracil-Resistant HER2+ Breast Cancer Cells to 5-Fluorouracil.

5-Fluorouracil (5-FU) is a widely used chemotherapeutic agent for breast cancer. However, acquired chemoresistance leads to a loss of its efficacy; methods to reverse are urgently needed. Some studies have shown that pyrotinib, an ErbB receptor tyrosine kinase inhibitor, is effective against HER2+ breast cancer. However, whether pyrotinib sensitizes 5-FU-resistant breast cancer cells to 5-FU is unknown. We hypothesized that the combination of pyrotinib and 5-FU would show synergistic antitumor activity, and pyrotinib could reverse 5-FU resistance in HER2+ breast cancer cells in vitro and in vivo. Our data showed that pyrotinib inhibited the growth of 5-FU-resistant SKBR-3/FU and MDA-MB-453/FU cell lines and the parental cell lines. 5-FU remarkably suppressed the growth of SKBR-3 and MAD-MB-453 cells. However, SKBR-3/FU and MAD-MB-453/FU cells showed resistance to 5-FU. A combination of pyrotinib and 5-FU resulted in the synergistic inhibition of the growth of the 5-FU-resistant SKBR-3/FU and MDA-MB-453/FU cell lines and the parental cell lines. Pyrotinib decreased significantly the IC50 values of 5-FU and the thymidylate synthase (TS) mRNA expression levels in the 5-FU-resistant SKBR-3/FU and MDA-MB-453/FU cell lines and the parental cell lines and increased significantly the intracellular concentration of 5-FU in SKBR-3/FU and MDA-MB-453/FU cells. In addition, pyrotinib reduced the ABCG2 mRNA and protein expression levels in SKBR-3/FU and MDA-MB-453/FU cells and downregulated the protein expression levels of pAKT, pHER2, and pHER4 in all four cell lines. After TS or ABCG2 in 5-FU-resistant breast cancer cells was knocked down, the sensitivity of SKBR-3/FU and MDA-MB-453/FU cells to 5-FU was restored. Moreover, in vivo experiments demonstrated that pyrotinib in combination with 5-FU more effectively inhibited SKBR-3/FU tumor growth than either pyrotinib or 5-FU alone. In conclusion, our findings suggest that pyrotinib could restore sensitivity of 5-FU-resistant HER2+ breast cancer cells to 5-FU through downregulating the expression levels of TS and ABCG2.

Intestinal epithelial potassium channels and CFTR chloride channels activated in ErbB tyrosine kinase inhibitor diarrhea.

Diarrhea is a major side effect of ErbB receptor tyrosine kinase inhibitors (TKIs) in cancer chemotherapy. Here, we show that the primary mechanism of ErbB TKI diarrhea is activation of basolateral membrane potassium (K+) channels and apical membrane chloride (Cl-) channels in intestinal epithelia and demonstrate the efficacy of channel blockers in a rat model of TKI diarrhea. Short-circuit current in colonic epithelial cells showed that the TKIs gefitinib, lapatinib, and afatinib do not affect basal secretion but amplify carbachol-stimulated secretion by 2- to 3-fold. Mechanistic studies with the second-generation TKI afatinib showed that the amplifying effect on Cl- secretion was Ca2+ and cAMP independent, was blocked by CF transmembrane conductance regulator (CFTR) and K+ channel inhibitors, and involved EGFR binding and ERK signaling. Afatinib-amplified activation of basolateral K+ and apical Cl- channels was demonstrated by selective membrane permeabilization, ion substitution, and channel inhibitors. Rats that were administered afatinib orally at 60 mg/kg/day developed diarrhea with increased stool water from approximately 60% to greater than 80%, which was reduced by up to 75% by the K+ channel inhibitors clotrimazole or senicapoc or the CFTR inhibitor (R)-BPO-27. These results indicate a mechanism for TKI diarrhea involving K+ and Cl- channel activation and support the therapeutic efficacy of channel inhibitors.

Interleukin-6 and neuregulin-1 as regulators of utrophin expression via the activation of NRG-1/ErbB signaling pathway in mdx cells

Duchenne muscular dystrophy (DMD) is a neuromuscular disease originated by mutations in the dystrophin gene. A promising therapeutic approach deals with functional substitution of dystrophin by utrophin, a structural homolog that might be able to compensate dystrophin absence in DMD muscle fibers.It has been described that both interleukin-6 (IL-6) and neuregulin-1 (NRG-1; Heregulin-HRG) induce utrophin expression in skeletal muscle. We investigated a possible functional link among IL-6, NRG-1 and utrophin, in normal (C57) and dystrophic (mdx) skeletal muscle cells. Western Blot analysis allowed us to demonstrate that IL-6 (100ng/mL) induces NRG-1 receptor phosphorylation (ErbB2/ErbB3) in both cell types, in a process that depends on intracellular Ca2+ and metalloproteinase activity; it also induces a transient increase of ERK1 and GABPα phosphorylation only in dystrophic myotubes. Semiquantitative PCR showed that IL-6 treatment increases utrophin mRNA levels just in mdx myotubes. We observed that utrophin mRNA induction was abolished by BAPTA-AM (an intracellular Ca2+ chelator), GM6001 (a general metalloproteinase inhibitor), genistein (a general protein tyrosine kinase inhibitor), PD-158780 (an ErbB receptor tyrosine kinase inhibitor) and PD-98059 (a MEK inhibitor), whereas Ly-294002 and wortmannin (PI3K inhibitors) did not affect utrophin induction evoked by IL-6 in dystrophic myotubes.Our results suggest that IL-6 induces utrophin expression in mdx myotubes through activation of a NRG-1/ErbBs signaling cascade. Soluble NRG-1 elicited by proteolytic processing of transmembrane NRG-1 might induce ErbBs phosphorylation and ERK1/2 pathway activation, leading to utrophin up-regulation.

Neratinib, an irreversible ErbB receptor tyrosine kinase inhibitor, shows efficacy in the treatment of HER2 amplified carcinosarcoma in vitro and in vivo

Neratinib, an irreversible ErbB receptor tyrosine kinase inhibitor, shows efficacy in the treatment of HER2 amplified carcinosarcoma in vitro and in vivo

Interleukin‐6 induces ErbBs receptor phosphorylation and utrophin expression in dystrophic myotubes.

Duchenne muscular dystrophy (DMD) is a neuromuscular disease originated by mutations in the dystrophin gene, leading to skeletal muscle fiber loss. A promising pharmacological treatment aims to increase the level of utrophin, a functional dystrophin homolog that could compensate dystrophin absence in DMD muscle fibers. It has been described that interleukin‐6 (IL‐6) and neuregulin‐1 (NRG‐1) induce utrophin expression in skeletal muscle.We investigated a possible functional link among IL‐6, NRG‐1 and utrophin, in normal (C57) and dystrophic (mdx) skeletal muscle cells.Using Western Blot and semiquantitative PCR, we demonstrated that IL‐6 (100 ng/ml) induces NRG‐1 receptor phosphorylation (ErbB2/ErbB3) in both cellular types, and a transient increase on utrophin mRNA levels in dystrophic myotubes. We observed that BAPTA‐AM (an intracellular Ca2+ chelator), GM6001 (a general metalloproteinase inhibitor), genistein (a general protein tyrosine kinase inhibitor) and PD‐158780 (an ErbB receptor tyrosine kinase inhibitor) treatment abolished utrophin mRNA induction.Our results suggest that IL‐6 induces utrophin expression in dystrophic myotubes, through NRG‐1/ErbBs signaling activation, elicited by proteolytic processing of NRG‐1 and ErbBs phosphorylation. Understanding the mechanism involved on utrophin up regulation could help to the development of DMD new therapies.FONDECYT 11100267

Impact of neratinib on patient-reported outcomes.

e11078 Background: Neratinib, an irreversible ErbB receptor tyrosine kinase inhibitor was evaluated in an open label multi-center phase 2 study, with a daily oral dose in advanced breast cancer patients split into 2 cohorts, based on prior trastuzumab (n=66) and no prior trastuzumab treatment (n=70) with the primary endpoint being 16- week progression free survival rate (59% vs 78% with and without prior trastuzumab respectively) as reported by Burstein et al. Here we assess the impact of Neratinib on patient reported outcomes (PROs). Methods: PROs were measured as secondary endpoints at screening, months 3, 5 and final visit using EORTC-QLQ breast cancer module (BR-23) that includes 5 multi-item scales assessing breast symptoms, arm symptoms, side effects, body image, sexual functioning and 3 items assessing sexual enjoyment, hair loss and future perspective. Items are measured on a 4-point Likert scale ranging from 1 (not at all) to 4 (very much). Raw scores were transformed using a standard algorithm i...

Abstract A5: Characterization of signaling pathways related to resistance of breast cancer cells against irreversible EGFR/HER/ErbB kinase inhibitors

Abstract Epidermal growth factor (EGF) receptor-related antigens (EGFR, ErbB1-4, HER1-4) represent emerging drug targets in oncology. However, resistance against ErbB-targeting drugs occurs frequently in cancer patients. Drug-resistant cells may exhibit drug-refractory phosphatidylinositol 3-kinase (PI3K) or mitogen-activated protein kinase (MAPK) signaling, but the relative impact and contribution of these two downstream pathways to drug resistance are still controversially discussed. We examined the effects of the two very potent, irreversibly binding ErbB receptor tyrosine kinase inhibitors (RTKIs) pelitinib (EKB-569) and canertinib (CI-1033) on PI3K- and MAPK activity in ErbB RTKI-sensitive and ErbB RTKI-resistant breast and ovarian cancer cells. Western blot analysis revealed that ErbB phosphorylation was abrogated by the inhibitors in both drug-sensitive and drug-resistant cells, whereas AKT- and GSK3β phosphorylation were drug-dependently downregulated only in drug-sensitive cells. ErbB RTKI sensitivity did not correlate with expression of wildtype PTEN or PIK3CA, nor was it associated with drug-dependent silencing of ERK1,2 in the breast and ovarian cancer cell lines examined. Moreover, exogenous AKT, but not MEK, significantly induced drug resistance. Our data demonstrate that blocking AKT phosphorylation is essential and sufficient, whereas abrogation of ERK phosphorylation is not required for ErbB RTKI anticancer efficacy. AKT phosphorylation may thus be a useful biomarker of ErbB RTKI sensitivity in breast and ovarian cancer cells. Supported by ‘MedizinischWissenschaftlicher Fonds des Bürgermeisters der Bundeshauptstadt Wien’ (#08037) and ‘Initiative Krebsforschung’, Medical Univ. Vienna. Citation Information: Clin Cancer Res 2010;16(7 Suppl):A5

Neratinib (HKI-272), an irreversible pan erbB receptor tyrosine kinase inhibitor: phase 2 results in patients with advanced HER2+ breast cancer.

Abstract Abstract #37 Background: Neratinib (HKI-272) irreversibly inhibits the tyrosine kinase receptors, erbB1 (EGFR) and erbB2 (HER2). In a phase 1 study, neratinib was tolerable and demonstrated antitumor activity in patients (pts) with solid tumors, including 8 of 25 evaluable pts with erbB2-positive advanced breast cancer. In this open-label, 2-arm phase 2 study, pts with stage IIIB, IIIC or IV erbB2-positive advanced breast cancer were evaluated to further characterize the safety and efficacy of neratinib.
 Methods: ErbB2 gene amplification in tumor tissue, by FISH was a requirement for study entry. Pts were assigned to arm A if they had prior treatment with trastuzumab and to arm B if they had no prior treatment with trastuzumab or other erbB2-targeted drug. All pts received oral doses of 240 mg of neratinib daily. The primary endpoint was progression-free (PFS) survival rate at 16 weeks (wks).
 Results: Enrollment of 136 pts (arm A: 66 pts; arm B: 70 pts; median age 50 years [range 31-83 years]) was completed in November 2007. Common neratinib-related adverse events (AEs), any grade, were diarrhea (89%), nausea (29%), vomiting (23%), fatigue (16%), and anorexia (15%). Diarrhea was the only ≥grade 3 AE that occurred in ≥5% of pts, 26/136 (19%) total pts, 27% in arm A and 11% in arm B. Dose reductions occurred in 27% total pts, 36% in arm A and 19% in arm B, most commonly because of diarrhea. The main reasons for discontinuation of the study were disease progression (arm A: 74%, arm B: 43%), and AEs (arm A: 8%, arm B: 4%).
 124 pts (arm A: 61 pts, arm B: 63 pts) were evaluable for efficacy based on independent assessment and 131 pts (arm A: 65 pts, arm B: 66 pts) were evaluable based on investigator assessment. The objective response rates (complete or partial response) were 26% (95% CI 16%, 39%) in arm A, 51% (95% CI: 38%, 64%) in arm B for independent assessment and 34% (95% CI: 23%, 47%) in arm A, 62% (95% CI: 49%, 74%) in arm B for investigator assessment. The 16-wk PFS rates were 61% in arm A, 75% in arm B (independent); 57% in arm A, and 78% in arm B (investigator). The median PFS for independent [and investigator assessment] was 23 [22] wks in arm A and 40 [35] wks in arm B.
 Discussion: Neratinib demonstrates robust antitumor activity in pts with erbB2-positive advanced breast cancer, with objective response rates of 26% in pts who had prior treatment with trastuzumab and 51% in pts who had no prior treatment with trastuzumab. Additional updated efficacy and safety data will be presented. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 37.

HKI-272, an irreversible pan erbB receptor tyrosine kinase inhibitor: Preliminary phase 1 results in patients with solid tumors

3018 Background: HKI-272 is a potent, low molecular weight, orally active, irreversible pan erbB receptor tyrosine kinase inhibitor. It inhibits the growth of tumor cells that express erbB-1 (epidermal growth factor receptor, EGFR) and erbB-2 (HER-2) in culture and xenografts. HKI-272 also inhibits the growth of cultured cells that contain sensitizing and resistance-associated EGFR mutations (Kwak et al, Proc Natl Acad Sci USA 102:7665–70, 2005). We are conducting a phase 1 study in patients (pts) with advanced-stage tumors that express EGFR or HER-2 to assess HKI-272 for tolerability, safety, pharmacokinetics, and preliminary antitumor activity. Methods: Pts (3–6/cohort) received 40, 80, 120, 180, 240, 320, or 400 mg HKI-272 orally once on day 1 and then once daily beginning on day 8. Timed blood samples were collected on days 1 and 21 for pharmacokinetic analysis. Results: Enrollment of 73 pts is complete. Preliminary data for 51 pts as of 28 Nov 2005 are presented. Patients were a median 60 years and 26% men. The most frequently occurring tumor types at primary diagnosis were breast (23 pts), non-small cell lung (9), and colorectal, ovarian, and renal (3 pts each). Dose escalation ended when 2 pts who received 400 mg HKI-272/day had drug-related dose-limiting toxicity of grade 3 diarrhea. Thus, the maximum tolerated dose (MTD) was 320 mg HKI-272/day. HKI-272-related adverse events (AEs), any grade, that occurred in ≥10% of pts were diarrhea (84%), nausea (55%), asthenia (45%), anorexia (31%), vomiting (29%), chills (12%), and rash (10%). Grade 3 related AEs that occurred in >1 pt were diarrhea (11) and asthenia (4). HKI-272 Cmax and AUC increased in a dose-dependent manner. At steady state at the MTD, mean values were Cmax: 112±58 ng/mL, AUC: 1618±930 ng.h/mL, t1/2: 15±2.5 h. Day 1 and 21 AUC values were comparable. Tumor assessments (modified RECIST criteria) were made at baseline and at the end of alternate cycles (28 days/cycle). Two breast cancer pts had confirmed partial responses (PRs) and 2 had unconfirmed PRs. Conclusions: When HKI-272 was administered on a continuous, once-daily, oral treatment schedule, the MTD was 320 mg/day, with diarrhea as the most frequently occurring related AE. HKI-272 has antitumor activity in HER-2-positive breast cancer. [Table: see text]

Neuregulin-1 Reverses Long-Term Potentiation at CA1 Hippocampal Synapses

Neuregulin-1 (NRG-1) has been identified genetically as a schizophrenia susceptibility gene, but its function in the adult brain is unknown. Here, we show that NRG-1beta does not affect basal synaptic transmission but reverses long-term potentiation (LTP) at hippocampal Schaffer collateral-->CA1 synapses in an activity- and time-dependent manner. Depotentiation by NRG-1beta is blocked by two structurally distinct and selective ErbB receptor tyrosine kinase inhibitors. Moreover, ErbB receptor inhibition increases LTP at potentiated synapses and blocks LTP reversal by theta-pulse stimuli. NRG-1beta selectively reduces AMPA, not NMDA, receptor EPSCs and has no effect on paired-pulse facilitation ratios. Live imaging of hippocampal neurons transfected with receptors fused to superecliptic green fluorescent protein, as well as quantitative analysis of native receptors, show that NRG-1beta stimulates the internalization of surface glutamate receptor 1-containing AMPA receptors. This novel regulation of LTP by NRG-1 has important implications for the modulation of synaptic homeostasis and schizophrenia.

Autocrine extracellular signal-regulated kinase (ERK) activation in normal human keratinocytes: metalloproteinase-mediated release of amphiregulin triggers signaling from ErbB1 to ERK.

ErbB signaling through extracellular signal-regulated kinase (ERK) has been implicated in regulating the expression of ErbB ligands in hyperproliferative skin disorders and wound healing. Here, we characterize the process of autocrine ERK activation in cultured normal human keratinocytes (NHKs) subjected to growth factor (GF) deprivation. Basal ERK phosphorylation was lower after 48 h than after 24 h of GF deprivation, and lowest at 30-60 min after an additional medium change. ERK phosphorylation was markedly increased by low concentrations of epidermal growth factor (EGF) (0.2-1 ng/ml) that provoked only a limited increase in ErbB1 tyrosine phosphorylation and internalization. Basal ErbB tyrosine phosphorylation and ERK phosphorylation were inhibited by two different ErbB receptor tyrosine kinase inhibitors, by the ErbB1-specific neutralizing monoclonal antibody 225 IgG, by two different metalloproteinase inhibitors, and by neutralizing antibodies against amphiregulin (AR). In contrast, these responses were unaffected by neutralizing antibodies against other ErbB1 ligands or the ErbB2 inhibitors geldanamycin and AG825. The time course of autocrine ERK phosphorylation correlated with the appearance of soluble AR, and two different metalloproteinase inhibitors blocked AR release. These results define an amphiregulin- and ErbB1-dependent mechanism by which autocrine ERK activation is maintained in NHKs, even when ErbB1 autophosphorylation and internalization are limited.

ErbB receptor tyrosine kinase inhibitors as therapeutic agents

The ErbB family of receptor tyrosine kinases comprise four members: EGFR, ErbB2, ErbB3 and ErbB4. All are essential for normal development and participate in the functioning of normal cells. ErbB receptors, particularly EGFR and ErbB2 are commonly deregulated in certain prevalent forms of human cancer. Recently a number of small molecule inhibitors of the tyrosine kinase activity of these receptors have been developed. Some of these agents, known as TKIs, are progressing through clinical trials in patients with aberrant ErbB receptor expression in their tumors. This article provides a brief overview on the structure and biology of ErbB receptors and their ligands before discussing in detail the development and current status of ErbB receptor TKIs. These agents are shown to inhibit multiple features of cancer cells including proliferation, survival, invasion and angiogenesis. It is clear from recent studies that not all cancer cells that overexpress ErbB receptors will be sensitive to TKIs. Potential explanations for resistance to these molecules are reviewed. Finally the prospect of using TKIs in combination with existing chemotherapeutic agents is discussed.

ErbB receptor tyrosine kinase inhibitors as therapeutic agents.

The ErbB family of receptor tyrosine kinases comprise four members: EGFR, ErbB2, ErbB3 and ErbB4. All are essential for normal development and participate in the functioning of normal cells. ErbB receptors, particularly EGFR and ErbB2 are commonly deregulated in certain prevalent forms of human cancer. Recently a number of small molecule inhibitors of the tyrosine kinase activity of these receptors have been developed. Some of these agents, known as TKIs, are progressing through clinical trials in patients with aberrant ErbB receptor expression in their tumors. This article provides a brief overview on the structure and biology of ErbB receptors and their ligands before discussing in detail the development and current status of ErbB receptor TKIs. These agents are shown to inhibit multiple features of cancer cells including proliferation, survival, invasion and angiogenesis. It is clear from recent studies that not all cancer cells that overexpress ErbB receptors will be sensitive to TKIs. Potential explanations for resistance to these molecules are reviewed. Finally the prospect of using TKIs in combination with existing chemotherapeutic agents is discussed.