Kotaro Miyake

Overcoming chemoresistance of small-cell lung cancer through stepwise HER2-targeted antibody-dependent cell-mediated cytotoxicity and VEGF-targeted antiangiogenesis

Small-cell lung cancer (SCLC) easily recurs with a multidrug resistant phenotype. However, standard therapeutic strategies for relapsed SCLC remain unestablished. We found that human epidermal growth factor receptor 2 (HER2) is not only expressed in pretreated human SCLC specimens, but is also upregulated when HER2-positive SCLC cells acquire chemoresistance. Trastuzumab induced differential levels of antibody-dependent cell-mediated cytotoxicity (ADCC) to HER2-positive SCLC cells. Furthermore, as a mechanism of the differential levels of ADCC, we have revealed that coexpression of intracellular adhesion molecule (ICAM)-1 on SCLC cells is essential to facilitate and accelerate the trastuzumab-mediated ADCC. Although SN-38–resistant SCLC cells lacking ICAM-1 expression were still refractory to trastuzumab, their in vivo growth was significantly suppressed by bevacizumab treatment due to dependence on their distinctive and abundant production of vascular endothelial growth factor. Collectively, stepwise treatment with trastuzumab and bevacizumab is promising for the treatment of chemoresistant SCLC.

Favorable response to trastuzumab plus irinotecan combination therapy in two patients with HER2-positive relapsed small-cell lung cancer

Small-cell lung cancer (SCLC) easily recurs with multidrug resistance phenotype. However, standard therapeutic strategies for relapsed-SCLC remain unestablished. Human epidermal growth factor receptor 2 (HER2) expression correlates with poor prognosis in extensive disease-SCLC. We have reported previously that HER2 expression is upregulated when HER2-positive SCLC cells acquire chemoresistance, and also demonstrated that trastuzumab exerts significant antitumor activity toward HER2-upregulated chemoresistant SCLC, mainly via antibody-dependent cell-mediated cytotoxicity mechanism. Based on these preclinical data, we treated two patients with HER2-positive SCLC by combination of trastuzumab (6 mg/kg, day 1) and irinotecan (80 mg/m(2), days 1 and 8) every 21 days as the third-line chemotherapy following two prior regimens, first-line carboplatin plus etoposide and second-line amrubicin. One patient achieved partial response after the first cycle and received 6 cycles in total without disease progression for 4.5 months. The other also received 4 cycles and kept stable disease for 3.5 months. This treatment can be continued safely at an outpatient clinic without any severe adverse event. In conclusion, trastuzumab plus irinotecan chemotherapy is promising and feasible against HER2-positive relapsed SCLC. Further clinical studies are encouraged to confirm the antitumor efficacy of trastuzumab in SCLC.

Dapsone Hypersensitivity Syndrome-related Lung Injury without Eosinophilia in the Bronchoalveolar Lavage Fluid

A 73-year-old man was admitted in respiratory failure that had subacutely progressed after five weeks of dapsone treatment for a skin rash. He also presented with fever, systemic erythroderma and liver dysfunction. Chest computed tomography showed diffuse reticular shadows with ground-glass opacity and bilateral mediastinal lymphadenopathy. Lymphocytes, but not eosinophils, were increased in the bronchoalveolar lavage fluid. Moreover, reactivation of human herpes virus-6 was confirmed on a paired serum test. Finally, we diagnosed the patient with dapsone hypersensitivity syndrome (DHS), a rare adverse event of this drug. Lung injury unaccompanied by eosinophilia in the bronchoalveolar lavage fluid is even more rare as a DHS-related lung manifestation.

Clarifying the biological significance of the CHK2 K373E somatic mutation discovered in The Cancer Genome Atlas database

We identified CHK2 K373E as a recurrent mutation in The Cancer Genome Atlas (TCGA) database. In this study, we demonstrate that the K373E mutation disrupts CHK2 autophosphorylation as well as kinase activity, thus leading to impairment of CHK2 functions in suppressing cell proliferation and promoting cell survival after ionizing radiation. We propose that K373E impairs p53‐independent induction of p21WAF1/CIP1 by CHK2. Our data implicate the K373E mutation of CHK2 in tumorigenesis.

Double deletion of tetraspanins CD9 and CD81 in mice leads to a syndrome resembling accelerated aging

Chronic obstructive pulmonary disease (COPD) has been recently characterized as a disease of accelerated lung aging, but the mechanism remains unclear. Tetraspanins have emerged as key players in malignancy and inflammatory diseases. Here, we found that CD9/CD81 double knockout (DKO) mice with a COPD-like phenotype progressively developed a syndrome resembling human aging, including cataracts, hair loss, and atrophy of various organs, including thymus, muscle, and testis, resulting in shorter survival than wild-type (WT) mice. Consistent with this, DNA microarray analysis of DKO mouse lungs revealed differential expression of genes involved in cell death, inflammation, and the sirtuin-1 (SIRT1) pathway. Accordingly, expression of SIRT1 was reduced in DKO mouse lungs. Importantly, siRNA knockdown of CD9 and CD81 in lung epithelial cells additively decreased SIRT1 and Foxo3a expression, but reciprocally upregulated the expression of p21 and p53, leading to reduced cell proliferation and elevated apoptosis. Furthermore, deletion of these tetraspanins increased the expression of pro-inflammatory genes and IL-8. Hence, CD9 and CD81 might coordinately prevent senescence and inflammation, partly by maintaining SIRT1 expression. Altogether, CD9/CD81 DKO mice represent a novel model for both COPD and accelerated senescence.

Abstract 3416: Clarifying the biological significance of the CHK2 K373E somatic mutation discovered in The Cancer Genome Atlas database

Identification of somatic mutations that contribute to cancer development leads not only to more precise understanding of cancer pathogenesis, but also development of novel molecular targeted therapies. Analyses of cancer genomes using high-throughput sequencing technology are currently conducted as international collaborative research projects, and the results of those analyses are deposited in public databases, allowing everyone in the world to access to these data. To identify a somatic mutation that plays an important role in cancer pathogenesis, we counted the occurrences of each somatic mutation found in the TCGA lung adenocarcinoma dataset and became interested in the CHK2 K373E mutation (c1117A>G), which was present in 31 of 542 patients. The K373E mutation impaired CHK2 autophosphorylation at Thr383 and Ser516. In vitro kinase assay revealed that the K373E mutation markedly attenuates CHK2 kinase activity. Growth curves showed that wild-type CHK2 substantially suppressed cell proliferation, but this effect was lost in the K373E mutant in HCT-15 harboring tetracycline-inducible CHK2. Clonogenic assays revealed that wild-type CHK2 promoted survival after ionizing radiation and this pro-survival function was impaired in K373E CHK2. The results of western blotting and RT-PCR suggested that the p53-independent induction of p21 by CHK2 might underlie these effects. Therefore, we identified a somatic mutation that contributes to cancer pathogenesis, using information in a public database. This kind of attempt is expected to lead to discovering new 9driver9 mutations in the future. Citation Format: Masayoshi Higashiguchi, Izumi Nagatomo, Takashi Kijima, Osamu Morimura, Kotaro Miyake, Toshiyuki Minami, Shohei Koyama, Haruhiko Hirata, Kota Iwahori, Takayuki Takimoto, Yoshito Takeda, Hiroshi Kida, Atsushi Kumanogoh. Clarifying the biological significance of the CHK2 K373E somatic mutation discovered in The Cancer Genome Atlas database [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3416. doi:10.1158/1538-7445.AM2017-3416

Abstract 4506: Targeting stepwise HER2 and VEGF can overcome multidrug resistance in small cell lung cancer

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Small-cell lung cancer (SCLC) accounts for approximately 15% of primary lung cancer and has the poorest outcome of all its histological types. One of the major reasons of extreme aggressiveness of SCLC is that it recurs shortly after initial therapy with multidrug resistance (MDR) phenotype. However, standard therapeutic strategy for relapsed-SCLC has not been established yet. As one of the targetable receptor tyrosine kinases, human epidermal growth factor receptor 2 (HER2) was reported to be a negative prognostic factor in extensive-disease SCLC (Micke et al. Int J Cancer. 2001;92:474-9). We found that HER2 was more frequently overexpressed in SCLC cell lines of Japanese origin (6/10) compared to those of Caucasian origin (0/3). We also detected HER2 expression in SCLC tissues in 7 out of 25 patients tested by our highly sensitive immunohistochemistry system. Moreover, we found that HER2 was upregulated when HER2-positive SCLC cells acquired MDR. Trastuzumab, a humanized monoclonal antibody against HER2, exerted differential levels of killing effect on HER2-positive parental and chemoresistant SCLC cells only when Fcγ receptor-positive natural killer (NK) cells coexisted. This result suggests that trastuzumab-induced SCLC cell-killing effect was caused mainly via antibody-dependent cell-mediated cytotoxicity (ADCC) but not via direct inhibition of HER2 signal. Among these cell lines, etoposide-resistant SCLC cells were most susceptible to trastuzumab in vitro and in vivo, and the antitumor effects of trastuzumab were not only dependent on the amount of HER2 expression on SCLC cells. We focused on cell-cell contact between SCLC cells and NK cells to determine the molecule affecting trastuzumab-mediated ADCC other than HER2. We found that intercellular adhesion molecule (ICAM)-1 was abundantly expressed on etoposide-resistant SCLC cells, and trastuzumab-mediated ADCC was canceled in the presence of an ICAM-1 functional blocking antibody. These results indicate that ICAM-1 expression on SCLC cell surface is indispensable to augment trastuzumab-mediated ADCC. Thus, trastuzumab could overcome etoposide-resistance in SCLC. On the contrary, irinotecan-resistant SCLC cells were still refractory to trastuzumab. The reason for this was thought that they not only lacked ICAM-1 expression but also came to produce abundant vascular endothelial growth factor (VEGF). Bevacizumab, a humanized monoclonal antibody against VEGF, treatment could significantly inhibit the in vivo growth of irinotecan-resistant xenografts through decreasing microvesseles in mice. These results suggest that bevacizumab-mediated antiangiogenesis is a promising therapeutic strategy to salvage irinotecan-resistance. Collectively, targeting stepwise HER2 and VEGF could overcome MDR in SCLC and bring about a favorable outcome for patients with relapsed-SCLC. Citation Format: Toshiyuki Minami, Takashi Kijima, Osamu Morimura, Yuhei Kinehara, Masayoshi Higashiguchi, Kotaro Miyake, Haruhiko Hirata, Yoshiko Takeuchi, Kiyoharu Fukushima, Yoshitomo Hayama, Koji Inoue, Izumi Nagatomo, Yoshito Takeda, Hiroshi Kida, Atsushi Kumanogoh. Targeting stepwise HER2 and VEGF can overcome multidrug resistance in small cell lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4506. doi:10.1158/1538-7445.AM2014-4506