Suppression of c-Met-Overexpressing Tumors by a Novel c-Met/CD3 Bispecific Antibody

Phase 1 Study of the Selective c-MET Inhibitor, HS-10241, in Patients With Advanced Solid Tumors

Introduction

c-MET is an important therapeutic target for various cancers; however, the People's Republic of China currently retails only one specific c-MET inhibitor. Our preclinical study has revealed the high selectivity of HS-10241 to suppress c-MET. This phase 1 study aims to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of the selective c-MET inhibitor (HS-10241) in patients with advanced solid tumors.

Methods

Patients with locally advanced or metastatic solid tumors orally received a single or multiple dose of HS-10241 once daily or twice daily for 21 consecutive days, which included the following six regimens: 100 mg once daily, 200 mg once daily, 400 mg once daily, 600 mg once daily, 200 mg twice daily, and 300 mg twice daily. The treatment continued until disease progression, unacceptable toxicity, or treatment termination. The primary end point was the incidence of dose-limiting toxicity and maximal tolerated dose (MTD). Secondary end points included safety, tolerability, pharmacokinetics, and pharmacodynamics.

Results

A total of 27 patients with advanced NSCLC received HS-10241, and dose-limiting toxicity was observed in three patients after 600 mg once-daily HS-10241 treatment. For once-daily dosing, MTD was 400 mg, and for twice-daily dosing, the maximal safe escalated dose was 300 mg, and MTD was not reached. Nausea (48.1%, 13 of 27), fatigue (37.0%, 10 of 27), and anemia (33.3%, 9 of 27) are the three most frequent treatment-emergent adverse events. At 400 mg once daily, C_ss,max was 5076 ng/mL and steady state area under the curve was 39,998 h × ng/mL. Patients (n = 5) with positive MET (MET exon 14-skipping, MET amplified, and MET immunohistochemistry 3+) had confirmed partial responses (n = 1) or stable disease (n = 3), with a disease control rate of 80.0%.

Conclusions

The selective c-MET inhibitor HS-10241 was well tolerated and had clinical activity in advanced NSCLC, especially in patients with positive MET. Furthermore, this study expounds on the therapeutic potential of HS-10241 in patients with cancer.

Involvement of Met receptor pathway in aggressive behavior of colorectal cancer cells induced by parathyroid hormone-related peptide

BACKGROUND

Parathyroid hormone-related peptide (PTHrP) plays a key role in the development and progression of many tumors. We found that in colorectal cancer (CRC) HCT116 cells, the binding of PTHrP to its receptor PTHR type 1 (PTHR1) activates events associated with an aggressive phenotype. In HCT116 cell xenografts, PTHrP modulates the expression of molecular markers linked to tumor progression. Empirical evidence suggests that the Met receptor is involved in the development and evolution of CRC. Based on these data, we hypothesized that the signaling pathway trigged by PTHrP could be involved in the transactivation of Met and consequently in the aggressive behavior of CRC cells.

AIM

To elucidate the relationship among PTHR1, PTHrP, and Met in CRC models.

METHODS

For in vitro assays, HCT116 and Caco-2 cells derived from human CRC were incubated in the absence or presence of PTHrP (1-34) (10^-8 M). Where indicated, cells were pre-incubated with specific kinase inhibitors or dimethylsulfoxide, the vehicle of the inhibitors. The protein levels were evaluated by Western blot technique. Real-time polymerase chain reaction (RT-qPCR) was carried out to determine the changes in gene expression. Wound healing assay and morphological monitoring were performed to evaluate cell migration and changes related to the epithelial-mesenchymal transition (EMT), respectively. The number of viable HCT116 cells was counted by trypan blue dye exclusion test to evaluate the effects of irinotecan (CPT-11), oxaliplatin (OXA), or doxorubicin (DOXO) with or without PTHrP. For in vivo tests, HCT116 cell xenografts on 6-wk-old male N:NIH (S)_nu mice received daily intratumoral injections of PTHrP (40 μg/kg) in 100 μL phosphate-buffered saline (PBS) or the vehicle (PBS) as a control during 20 d. Humanitarian slaughter was carried out and the tumors were removed, weighed, and fixed in a 4% formaldehyde solution for subsequent treatment by immunoassays. To evaluate the expression of molecular markers in human tumor samples, we studied 23 specimens obtained from CRC patients which were treated at the Hospital Interzonal de Graves y Agudos Dr. José Penna (Bahía Blanca, Buenos Aires, Argentina) and the Hospital Provincial de Neuquén (Neuquén, Neuquén, Argentina) from January 1990 to December 2007. Seven cases with normal colorectal tissues were assigned to the control group. Tumor tissue samples and clinical histories of patients were analyzed. Paraffin-embedded blocks from primary tumors were reviewed by hematoxylin-eosin staining technique; subsequently, representative histological samples were selected from each patient. From each paraffin block, tumor sections were stained for immunohistochemical detection. The statistical significance of differences was analyzed using proper statistical analysis. The results were considered statistically significant at P < 0.05.

RESULTS

By Western blot analysis and using total Met antibody, we found that PTHrP regulated Met expression in HCT116 cells but not in Caco-2 cells. In HCT116 cells, Met protein levels increased at 30 min (P < 0.01) and at 20 h (P < 0.01) whereas the levels diminished at 3 min (P < 0.05), 10 min (P < 0.01), and 1 h to 5 h (P < 0.01) of PTHrP treatment. Using an active Met antibody, we found that where the protein levels of total Met decreased (3 min, 10 min, and 60 min of PTHrP exposure), the status of phosphorylated/activated Met increased (P < 0.01) at the same time, suggesting that Met undergoes proteasomal degradation after its phosphorylation/activation by PTHrP. The increment of its protein level after these decreases (at 30 min and 20 h) suggests a modulation of Met expression by PTHrP in order to improve Met levels and this idea is supported by our observation that the cytokine increased Met mRNA levels at least at 15 min in HCT116 cells as revealed by RT-qPCR analysis (P < 0.05). We then proceeded to evaluate the signaling pathways that mediate the phosphorylation/ activation of Met induced by PTHrP in HCT116 cells. By Western blot technique, we observed that PP1, a specific inhibitor of the activation of the proto-oncogene protein tyrosine kinase Src, blocked the effect of PTHrP on Met phosphorylation (P < 0.05). Furthermore, the selective inhibition of the ERK 1/2 mitogen-activated protein kinase (ERK 1/2 MAPK) using PD98059 and the p38 MAPK using SB203580 diminished the effect of PTHrP on Met phosphorylation/activation (P < 0.05). Using SU11274, the specific inhibitor of Met activation, and trypan blue dye exclusion test, Western blot, wound healing assay, and morphological analysis with a microscope, we observed the reversal of cell events induced by PTHrP such as cell proliferation (P < 0.05), migration (P < 0.05), and the EMT program (P < 0.01) in HCT116 cells. Also, PTHrP favored the chemoresistance to CPT-11 (P < 0.001), OXA (P < 0.01), and DOXO (P < 0.01) through the Met pathway. Taken together, these findings suggest that Met activated by PTHrP participates in events associated with the aggressive phenotype of CRC cells. By immunohistochemical analysis, we found that PTHrP in HCT116 cell xenografts enhanced the protein expression of Met (0.190 ± 0.014) compared to tumors from control mice (0.110 ± 0.012; P < 0.05) and of its own receptor (2.27 ± 0.20) compared to tumors from control mice (1.98 ± 0.14; P < 0.01). Finally, assuming that the changes in the expression of PTHrP and its receptor are directly correlated, we investigated the expression of both Met and PTHR1 in biopsies of CRC patients by immunohistochemical analysis. Comparing histologically differentiated tumors with respect to those less differentiated, we found that the labeling intensity for Met and PTHR1 increased and diminished in a gradual manner, respectively (P < 0.05).

CONCLUSION

PTHrP acts through the Met pathway in CRC cells and regulates Met expression in a CRC animal model. More basic and clinical studies are needed to further evaluate the PTHrP/Met relationship.

LINC00839 knockdown restrains the metastatic behavior of nasopharyngeal carcinoma by sponging miR-454-3p

Long intergenic non-coding RNA 00839 (LINC00839) has been verified as a pro-metastasis factor in malignancies. However, the significance of LINC00839 in nasopharyngeal carcinoma (NPC) has yet to be illuminated, as well as its underlying mechanism. Here, we disclosed that LINC00839 is highly expressed in NPC. Deletion of LINC00839 suppresses NPC cells rapid growth, invasive capacity and EMT in vitro. Besides, LINC00839 is identified as a "sponge" for miR-454-3p, and upregulation of LINC00839 reverses miR-454-3p-mediated inhibition of aggressiveness in NPC cells. Furthermore, the expression of cellular-mesenchymal epithelial transition factor (c-Met), the downstream target of miR-454-3p, is downregulated by LINC00839 knockdown in NPC cells. In vivo, LINC00839 knockdown retards the tumor growth of NPC cells in the xenografted mice model. Collectively, attenuation of LINC00839 expression attenuates the aggressive properties of NPC cells via directly sponging the miR-454-3p and regulating c-Met expression.

MET alterations and their impact on the future of non-small cell lung cancer (NSCLC) targeted therapies

Introduction: The MET gene and its pathway normally plays a crucial role in cell homeostasis, motility, and apoptosis. However, when the MET gene is altered, there is an imbalance toward cell proliferation and invasion commonly seen in numerous different types of cancers. The heterogeneous group of MET alterations that includes MET amplification, MET exon 14 skipping mutation, and MET fusions has been difficult to diagnose and treat. Currently, treatments are focused on tyrosine kinase inhibitors but now there is emerging data on novel MET-targeted therapies including monoclonal antibodies and antibody-drug conjugates that have emerged.Areas covered: We introduce new emerging data on MET alterations in non-small cell lung cancer (NSCLC) that has contributed to advances in MET targeted therapeutics. We offer our perspective and examine new information on the mechanisms of the MET alterations in this review.Expert opinion: Given the trends currently involving the targeting of MET altered malignancies, there will most likely be a continued rapid expansion of testing, novel tyrosine kinase inhibitors and potent antibody approaches. Combination treatments will be necessary to optimize management of advanced and early disease.

Overcoming Challenges for CD3-Bispecific Antibody Therapy in Solid Tumors

Immunotherapy of cancer with CD3-bispecific antibodies is an approved therapeutic option for some hematological malignancies and is under clinical investigation for solid cancers. However, the treatment of solid tumors faces more pronounced hurdles, such as increased on-target off-tumor toxicities, sparse T-cell infiltration and impaired T-cell quality due to the presence of an immunosuppressive tumor microenvironment, which affect the safety and limit efficacy of CD3-bispecific antibody therapy. In this review, we provide a brief status update of the CD3-bispecific antibody therapy field and identify intrinsic hurdles in solid cancers. Furthermore, we describe potential combinatorial approaches to overcome these challenges in order to generate selective and more effective responses.