Bo Mi Ku

High-throughput profiling identifies clinically actionable mutations in salivary duct carcinoma

BackgroundSalivary duct carcinoma (SDC) is a highly aggressive subtype of salivary gland cancers and there is no established standard therapy for this disease. Thus, development of molecular markers for SDC will be important to guide the diagnosis and therapy of this aggressive tumor.MethodsWe performed next-generation sequencing using the Ion Torrent AmpliSeq cancer panel, which explores the mutational status of hotspot regions in 50 cancer-associated genes, and we analyzed copy number variations (CNVs) of 21 genes by NanoString nCounter for 37 patients with SDC. Fluorescent in situ hybridization was also conducted to confirm ERBB2 gene amplification. Clinical records and tumor histopathology of the patients were retrospectively reviewed.ResultsGenetic alterations were detected in 29 of 37 (78.3%) tumors, including mutations in PIK3CA (N = 9, 24.3%), ERBB2 (N = 4, 10.8%), and EGFR (N = 4, 10.8%). To our knowledge, this is the first time that ERBB2 mutations have been reported in this tumor type. Both PIK3CA and ERBB2 mutation status were associated with poor overall survival, but without statistical significance. ERBB2 amplification was strong and common in SDC and almost all cases also exhibited EGFR and ERBB3 amplifications.ConclusionsThis study reports the largest and most comprehensive analysis of DNA aberrations in SDC. Our results show that PIK3CA and/or ERBB2 alterations in the development of SDC might be a useful diagnostic tool and could serve as a potential therapeutic target.

The CDK4/6 inhibitor LY2835219 has potent activity in combination with mTOR inhibitor in head and neck squamous cell carcinoma

Deletion of CDKN2A (p16) or amplification of CCND1 (cyclin D1) occurs commonly in head and neck squamous cell carcinoma (HNSCC) and induces sustained cyclin-dependent kinase (CDK) 4/6 activation. Here, we report the antiproliferative activity of LY2835219, a selective CDK4/6 inhibitor through inhibition of CDK4/6-dependent Ser780 phosphorylation in retinoblastoma (RB) and induction of cell cycle arrest in HNSCC cells. In addition, we demonstrated the antitumor effects of HNSCC xenografts to LY2835219 in vivo. Given the limited effect in HNSCC as a single-agent treatment with LY2835219, a combinational strategy is required to enhance antitumor activity. At the molecular level, we found that LY2835219 inhibited activation of AKT and ERK, but not mTOR. The combination of LY2835219 with mTOR inhibitor was found to be more effective than either drug alone in vitro and in vivo. Taken together, our findings suggest that a combinational treatment with LY2835219 and mTOR inhibitor is a promising therapeutic approach for HNSCC.

BYL719, a selective inhibitor of phosphoinositide 3-Kinase α, enhances the effect of selumetinib (AZD6244, ARRY-142886) in KRAS-mutant non-small cell lung cancer

SummaryPurposeKRAS is frequently mutated in non-small cell lung cancers (NSCLC), resulting in activation of the MEK/ERK pathway. Because there are currently no drugs that target oncogenic KRAS, MEK inhibitors have been tested clinically as a possible treatment option for patients with NSCLC. However, KRAS-mutant cancers exhibit resistance to MEK inhibitors. Therefore, a combinational strategy is necessary for effective therapy. To address this, we investigated the therapeutic effects of combining selumetinib, a MEK1/2 inhibitor, with BYL719, a PI3Kα inhibitor. Methods We evaluated the effects of selumetinib and BYL719 in vitro and in vivo in NSCLC cell lines. Results The combination of BYL719 and selumetinib resulted in synergistic cytotoxic activity compared with the single agents alone in KRAS-mutant NSCLC cells. At the molecular level, we found that AKT activation strongly influenced the sensitivity of KRAS-mutant NSCLC cells to selumetinib. Selumetinib upregulated phospho-AKT and phosphorylated BAD at ser136, which is responsible for intrinsic drug resistance in KRAS-mutant NSCLC cells. In contrast, inhibition of the PI3K/AKT pathway by BYL719 hindered selumetinib-induced BAD phosphorylation and increased the antitumor efficacy of selumetinib. Furthermore, selumetinib and BYL719 combination therapy showed synergy in the suppression of A549 xenograft tumor growth. On analysis of the pharmacodynamics, selumetinib and BYL719 together resulted in effective inhibition of both p-ERK and p-AKT expression in tumor tissue. Conclusion Taken together, these data suggest that combination treatment with selumetinib and BYL719 is a promising therapeutic approach to overcoming resistance to MEK inhibitors.

Genetic Alterations and Their Clinical Implications in High-Recurrence Risk Papillary Thyroid Cancer

Purpose Papillary thyroid carcinomas (PTCs) frequently involve genetic alterations. The objective of this study was to investigate genetic alterations and further explore the relationships between these genetic alterations and clinicopathological characteristics in a high-recurrence risk (node positive, N1) PTC group. Materials and Methods Tumor tissue blocks were obtained from 240 surgically resected patients with histologically confirmed stage III/IV (pT3/4 or N1) PTCs. We screened gene fusions using NanoString’s nCounter technology and mutational analysis was performed by direct DNA sequencing. Data describing the clinicopathological characteristics and clinical courses were retrospectively collected. Results Of the 240 PTC patients, 207 (86.3%) had at least one genetic alteration, including BRAF mutation in 190 patients (79.2%), PIK3CA mutation in 25 patients (10.4%), NTRK1/3 fusion in six patients (2.5%), and RET fusion in 24 patients (10.0%). Concomitant presence of more than two genetic alterations was seen in 36 patients (15%). PTCs harboring BRAF mutation were associated with RET wild-type expression (p=0.001). RET fusion genes have been found to occur with significantly higher frequency in N1b stage patients (p=0.003) or groups of patients aged 45 years or older (p=0.031); however, no significant correlation was found between other genetic alterations. There was no trend toward favorable recurrence-free survival or overall survival among patients lacking genetic alterations. Conclusion In the selected high-recurrence risk PTC group, most patients had more than one genetic alteration. However, these known alterations could not entirely account for clinicopathological features of high-recurrence risk PTC.

Mutational status of TP53 defines the efficacy of Wee1 inhibitor AZD1775 in KRAS -mutant non-small cell lung cancer

KRAS is frequently mutated in non-small cell lung cancer (NSCLC). However, direct targeting of KRAS has proven to be challenging, and inhibition of KRAS effectors has resulted in limited clinical efficacy. Wee1 kinase is an important regulator of the G2 checkpoint and is overexpressed in various cancers. Inhibition of Wee1 exerts anticancer effects as a monotherapy or in combination with DNA-damaging agents when cancer cells harbor TP53 mutations. However, its role in KRAS-mutant NSCLC, especially as a single agent, has not been explored. Here, we investigate the anticancer potential of Wee1 inhibitor AZD1775 as a monotherapy and uncover a possible cellular context underlying sensitivity to AZD1775. Our data show that treatment with AZD1775 significantly inhibited cell survival, growth, and proliferation of TP53-mutant (TP53MUT) compared to TP53 wild-type (TP53WT) in KRAS-mutant (KRASMUT) NSCLC cells. In KRASMUT/TP53MUT cells, AZD1775 treatment led to DNA damage, a decrease of survival signaling, and cell death by apoptosis. Interestingly, cell death through apoptosis was found to be heavily dependent on specific cellular genetic context, rather than inhibition of Wee1 kinase activity alone. In addition, AZD1775 treatment was well tolerated and displayed single-agent efficacy in a mouse xenograft model. This study provides rationale for inhibiting Wee1 using AZD1775 as a potential anticancer therapy against the TP53MUT subgroup of KRASMUT NSCLC.KRAS is frequently mutated in non-small cell lung cancer (NSCLC). However, direct targeting of KRAS has proven to be challenging, and inhibition of KRAS effectors has resulted in limited clinical efficacy. Wee1 kinase is an important regulator of the G2 checkpoint and is overexpressed in various cancers. Inhibition of Wee1 exerts anticancer effects as a monotherapy or in combination with DNA-damaging agents when cancer cells harbor TP53 mutations. However, its role in KRAS-mutant NSCLC, especially as a single agent, has not been explored. Here, we investigate the anticancer potential of Wee1 inhibitor AZD1775 as a monotherapy and uncover a possible cellular context underlying sensitivity to AZD1775. Our data show that treatment with AZD1775 significantly inhibited cell survival, growth, and proliferation of TP53-mutant (TP53MUT) compared to TP53 wild-type (TP53WT) in KRAS-mutant (KRASMUT) NSCLC cells. In KRASMUT/TP53MUT cells, AZD1775 treatment led to DNA damage, a decrease of survival signaling, and cell death by apoptosis. Interestingly, cell death through apoptosis was found to be heavily dependent on specific cellular genetic context, rather than inhibition of Wee1 kinase activity alone. In addition, AZD1775 treatment was well tolerated and displayed single-agent efficacy in a mouse xenograft model. This study provides rationale for inhibiting Wee1 using AZD1775 as a potential anticancer therapy against the TP53MUT subgroup of KRASMUT NSCLC.

Pembrolizumab for Patients With Refractory or Relapsed Thymic Epithelial Tumor: An Open-Label Phase II Trial

Purpose Limited treatment options exist for patients with thymic epithelial tumor (TET) whose disease progresses after platinum-based chemotherapy. We conducted a phase II study of pembrolizumab in patients with TET to evaluate its efficacy and safety. Methods Patients with histologically confirmed TET whose disease progressed after at least one line of platinum-based chemotherapy were eligible for the study. Patients were excluded if they had an active autoimmune disease requiring systemic treatment within the past year or documented history of clinically severe autoimmune disease. Patients received 200 mg of pembrolizumab intravenously every 3 weeks until tumor progression or unacceptable toxicity. The primary objective of response rate was assessed every 9 weeks by investigators. Results Of 33 patients enrolled, 26 had thymic carcinoma and seven had thymoma. Of seven thymoma, two (28.6%; 95% CI, 8.2% to 64.1%) had partial response, and five (71.6%) had stable disease. Of 26 thymic carcinoma, five (19.2%; 95% CI, 8.5% to 37.9%) had partial response and 14 (53.8%) had stable disease. The median progression-free survival was 6.1 months for both groups. The most common adverse events of any grade included dyspnea (11; 33.3%), chest wall pain (10; 30.3%), anorexia (seven; 21.2%), and fatigue (seven; 21.2%). Five (71.4%) of seven patients with thymoma and four (15.4%) of 26 patients with thymic carcinoma reported grade ≥ 3 immune-related adverse events, including hepatitis (four; 12.1%), myocarditis (three; 9.1%), myasthenia gravis (two; 6.1%), thyroiditis (one; 3.0%), antineutrophil cytoplasmic antibody-associated rapidly progressive glomerulonephritis (one; 3.0%), colitis (one; 3.0%), and subacute myoclonus (one; 3.0%). Conclusions Pembrolizumab showed encouraging antitumor activity in patients with advanced TET. Given the high incidence of autoimmunity, additional studies are needed to identify those who can benefit from pembrolizumab without immune-related adverse events.

Acquired resistance to AZD9291 as an upfront treatment is dependent on ERK signaling in a preclinical model

AZD9291 (osimertinib) is approved for standard care in patients with EGFR T790M-positive non-small cell lung cancer (NSCLC) after prior EGFR TKI progression. Furthermore, AZD9291 is now being evaluated as a first-line treatment for NSCLC patients with activation EGFR mutations. Based on previous experiments, resistance to AZD9291 as a first-line treatment may also emerge. Thus, identification and understanding of resistance mechanisms to AZD9291 as a first-line treatment can help direct development of future therapies. AZD9291-resistant cells (PC9/AZDR) were established using EGFR inhibitor-naïve PC9 cells. Resistance mechanisms were analyzed using next-generation sequencing (NGS) and a proteome profiler array. Resistance to AZD9291 developed through aberrant activation of ERK signaling by an EGFR-independent mechanism. The combination of a MEK inhibitor with AZD9291 restored the sensitivity of PC9/AZDR cells in vitro and in vivo. PC9/AZDR cells also showed increased MET expression and an HRAS G13R mutation. In addition, maspin expression was higher after AZD9291 treatment in PC9/AZDR cells. Sustained ERK activation confers resistance to AZD9291 as a first-line therapy. Thus, co-targeting EGFR and MEK may be an effective strategy to overcome resistance to AZD9291.

Abstract 2837: The CDK4/6 inhibitor has potent activity in combination with mTOR inhibitor in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a rare lethal human malignancy with no effective therapy. It is critical to identify new therapeutic strategies for NHSCC. Deregulation of CDKN2A (p16) or CCND1 (cyclin D1) occurs commonly in HNSCC and induces sustained cyclin-dependent kinase (CDK) 4/6 activation. The selective CDK4/6 inhibitor, LY2835219 inhibited CDK4/6-dependent Ser780 phosphorylation in retinoblastoma (RB) and induced cell cycle arrest and growth inhibition. In an animal xenograft model of HNSCC, LY2835219 treatment led to reduced tumor growth. However, because single-agent treatment with LY2835219 showed a limited effect in HNSCC, a combinational strategy is necessary for effective therapy. At the molecular level, we found that LY2835219 inhibited activation of AKT and ERK, but not mTOR. The combination of LY2835219 with mTOR inhibitor was found to be more effective than either drug alone in vitro and in vivo. Taken together, our findings suggest that a combination treatment with LY2835219 and mTOR inhibitor is a promising therapeutic approach for HNSCC. Citation Format: Bo Mi Ku, Jiae Koh, Yeon-Hee Bae, Jong-Mu Sun, Se-hoon Lee, Jin Seok Ahn, Keunchil Park, Myung-Ju Ahn. The CDK4/6 inhibitor has potent activity in combination with mTOR inhibitor in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2837.

Abstract 3897: High-throughput profiling of actionable mutations in salivary duct carcinoma

Salivary duct carcinoma (SDC) is a highly aggressive subtype of salivary gland cancers and there is no established standard therapy for this disease. Thus, development of molecular markers for SDC will be important to guide the diagnosis and therapy of this aggressive tumor. We performed next-generation sequencing using the Ion Torrent AmpliSeq cancer panel, which explores the mutational status of hotspot regions in 50 cancer-associated genes, and we analyzed copy number variations (CNVs) of 21 genes by NanoString nCounter for 37 patients with SDC. Fluorescent in situ hybridization was also conducted to confirm ERBB2 gene amplification. Clinical records and tumor histopathology of the patients were retrospectively reviewed. Genetic alterations were detected in 29 of 37 (78.3%) tumors, including mutations in PIK3CA (N = 9, 24.3%), ERBB2 (N = 4, 10.8%), and EGFR (N = 4, 10.8%). To our knowledge, this is the first time that ERBB2 mutations have been reported in this tumor type. Both PIK3CA and ERBB2 mutation status were associated with poor overall survival, but without statistical significance. ERBB2 amplification was strong and common in SDC and almost all cases also exhibited EGFR and ERBB3 amplifications. This study reports the largest and most comprehensive analysis of DNA aberrations in SDC. Our results show that PIK3CA and/or ERBB2 alterations in the development of SDC might be a useful diagnostic tool and could serve as a potential therapeutic target. Key words: Salivary duct carcinoma, next-generation sequencing, molecular markers, PIK3CA, ERBB2, EGFR Citation Format: Bo Mi Ku, Yeon-Hee Bae, Hyun Ae Jung, Jong-Mu Sun, Young Hyeh Ko, Han-Sin Jeong, Young-Ik Son, Chung-Hwan Baek, Keunchil Park, Myung-Ju Ahn. High-throughput profiling of actionable mutations in salivary duct carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3897. doi:10.1158/1538-7445.AM2015-3897