Case report: Navigating treatment pathways for cardiac intimal sarcoma with PDGFRß N666K mutation.

In the realm of rare cardiac tumors, intimal sarcoma presents a formidable challenge, often requiring innovative treatment approaches. This case report presents a unique instance of primary intimal sarcoma in the left atrium, underscoring the critical role of genomic profiling in guiding treatment. Initial genomic testing unveiled a somatic, active mutation in PDGFRß (PDGFRß N666K), accompanied by MDM2 and CDK4 amplifications. This discovery directed the treatment course toward pazopanib, a PDGFRß inhibitor, following irradiation. The patient's response was remarkable, with the therapeutic efficacy of pazopanib lasting for 16.3 months. However, the patient experienced a recurrence in the left atrium, where subsequent genomic analysis revealed the absence of the PDGFRß N666K mutation and a significant reduction in PDGFRß expression. This case report illustrates the complexities and evolving nature of cardiac intimal sarcoma treatment, emphasizing the potential of PDGFRß signaling as a strategic target and highlighting the importance of adapting treatment pathways in response to genetic shifts.

Safety and Efficacy of Encorafenib, Binimetinib, and Cetuximab for BRAFV600E-Mutant Metastatic Colorectal Cancer: Results of the Japanese Expanded Access Program.

BACKGROUND: The phase 3 BEACON CRC study demonstrated the survival benefits of encorafenib and cetuximab, with or without binimetinib (the BEACON triplet or doublet regimen), for BRAFV600E-mutant metastatic colorectal cancer (mCRC). This expanded access program (EAP) and subsequent follow-up study assessed the efficacy and safety of the BEACON triplet regimen in Japanese patients with BRAFV600E-mutant mCRC. MATERIALS AND METHODS: The EAP was an open-label, single-arm study including Japanese patients with BRAFV600E-mutant mCRC whose disease progressed after 1 to 2 prior regimens. The patients received the BEACON triplet regimen with 28-day cycles. The subsequent follow-up study assessed the survival outcomes following EAP completion. Safety was assessed only during the EAP. RESULTS: Among the 86 enrolled patients, 81 received the BEACON triplet regimen. The objective response rate and median progression-free survival were 27.6% (95% confidence interval [CI], 18.0%-39.1%) and 5.26 (95% CI, 4.14-5.52) months, respectively. Grade 3 to 4 adverse events and treatment-related adverse events occurred in 43.2% and 28.4% of patients, respectively. No new safety signals were observed during the EAP. Among 58 patients with confirmed survival at EAP completion, 57 were included in the follow-up study. With a median observation period of 9.17 months through the EAP and follow-up study, the median overall survival was 10.38 (95% CI, 9.00-16.16) months. CONCLUSION: The efficacy and safety of the BEACON triplet regimen in Japanese patients with BRAFV600E-mutant mCRC were consistent with those reported in the BEACON CRC trial, supporting its use as a standard treatment for pretreated patients with BRAFV600E-mutant mCRC.

Successful second-line treatment with cabozantinib for hepatocellular carcinoma harboring cytoplasmic mesenchymal-epithelial transition factor amplification.

A 72-year-old man with metastatic hepatocellular carcinoma previously received first-line systemic therapy with atezolizumab plus bevacizumab. His disease was judged to be progressing 5 months after treatment initiation. Comprehensive genomic profiling revealed cytoplasmic mesenchymal-epithelial transition factor amplification. On the basis of an expert panel's recommendation, he received cabozantinib as second-line therapy. The tumors shrank markedly and continued to shrink 6 months after treatment. Comprehensive genomic profiling could provide useful information for selecting effective second-line treatments for patients with hepatocellular carcinoma after first-line immunotherapy.

Development of ultrafast camera-based single fluorescent-molecule imaging for cell biology.

The spatial resolution of fluorescence microscopy has recently been greatly enhanced. However, improvements in temporal resolution have been limited, despite their importance for examining living cells. Here, we developed an ultrafast camera system that enables the highest time resolutions in single fluorescent-molecule imaging to date, which were photon-limited by fluorophore photophysics: 33 and 100 µs with single-molecule localization precisions of 34 and 20 nm, respectively, for Cy3, the optimal fluorophore we identified. Using theoretical frameworks developed for the analysis of single-molecule trajectories in the plasma membrane (PM), this camera successfully detected fast hop diffusion of membrane molecules in the PM, previously detectable only in the apical PM using less preferable 40-nm gold probes, thus helping to elucidate the principles governing the PM organization and molecular dynamics. Furthermore, as described in the companion paper, this camera allows simultaneous data acquisitions for PALM/dSTORM at as fast as 1 kHz, with 29/19 nm localization precisions in the 640 × 640 pixel view-field.

Ultrafast single-molecule imaging reveals focal adhesion nano-architecture and molecular dynamics.

Using our newly developed ultrafast camera described in the companion paper, we reduced the data acquisition periods required for photoactivation/photoconversion localization microscopy (PALM, using mEos3.2) and direct stochastic reconstruction microscopy (dSTORM, using HMSiR) by a factor of ≈30 compared with standard methods, for much greater view-fields, with localization precisions of 29 and 19 nm, respectively, thus opening up previously inaccessible spatiotemporal scales to cell biology research. Simultaneous two-color PALM-dSTORM and PALM-ultrafast (10 kHz) single fluorescent-molecule imaging-tracking has been realized. They revealed the dynamic nanoorganization of the focal adhesion (FA), leading to the compartmentalized archipelago FA model, consisting of FA-protein islands with broad diversities in size (13-100 nm; mean island diameter ≈30 nm), protein copy numbers, compositions, and stoichiometries, which dot the partitioned fluid membrane (74-nm compartments in the FA vs. 109-nm compartments outside the FA). Integrins are recruited to these islands by hop diffusion. The FA-protein islands form loose ≈320 nm clusters and function as units for recruiting FA proteins.

FIGHT-102: A phase 1 study of pemigatinib in Japanese patients with advanced malignancies.

BACKGROUND: FIGHT-102 was a phase 1, dose-escalation, dose-expansion study of pemigatinib in Japanese patients with advanced solid tumors. Here, we report safety, tolerability, and preliminary efficacy of pemigatinib from FIGHT-102. METHODS: Patients (≥20 years old) self-administered oral pemigatinib 9, 13.5, or 18 mg QD on intermittent dosing (Part 1) or 13.5 mg QD intermittent or continuous dosing (Part 2). A dosing cycle was 21 days (2 weeks on/1 week off or 21 continuous days). Primary endpoint was safety. Secondary endpoints were pharmacokinetics, pharmacodynamics, and preliminary efficacy. RESULTS: Forty-four patients (Part 1, n = 14; Part 2, n = 30) were enrolled; most common tumors, cholangiocarcinoma, n = 8; esophageal, n = 6; 26 patients had confirmed FGF/FGFR alterations (Part 1, n = 3; Part 2, n = 23); 70.5% had ≥3 prior systemic therapies. Maximum tolerated dose was not identified. The recommended phase 2 dosage was determined to be 13.5 mg QD. Most common treatment-emergent adverse events (TEAEs) were hyperphosphatemia (81.8%), dysgeusia (45.5%), stomatitis (43.2%), and alopecia (38.6%); most frequent Grade ≥3 TEAEs were anemia and decreased appetite (9.1% each). In Part 1, no patient achieved partial response (PR) or complete response, and 7 (50.0%) patients had stable disease (SD). In Part 2, 5 (16.7%) patients achieved PR (one each with cholangiocarcinoma, gall bladder cancer, breast cancer, urothelial tract/bladder cancer, and sweat gland carcinoma) and 6 (20%) had SD. Median duration of response was 9.56 months (95% CI: 4.17, 14.95). CONCLUSIONS: Pemigatinib demonstrated manageable adverse events, consistent pharmacokinetics and pharmacodynamics profiles, and preliminary efficacy in Japanese patients with advanced solid tumors.

MET kinase inhibitor reverses resistance to entrectinib induced by hepatocyte growth factor in tumors with NTRK1 or ROS1 rearrangements.

BACKGROUND: Entrectinib is an effective drug for treating solid tumors with NTRK gene rearrangement and non-small cell lung cancer (NSCLC) with ROS1 gene rearrangement. However, its efficacy is limited by tolerance and acquired resistance, the mechanisms of which are not fully understood. The growth factors produced by the tumor microenvironment, including hepatocyte growth factor (HGF) produced by tumor-associated fibroblasts, critically affect the sensitivity to targeted drugs. METHODS: We investigated whether growth factors that can be produced by the microenvironment affect sensitivity of NTRK1-rearranged colon cancer KM12SM cells and ROS1-rearranged NSCLC HCC78 cells to entrectinib both in vitro and in vivo. RESULTS: Among the growth factors assessed, HGF most potently induced entrectinib resistance in KM12SM and HCC78 cells by activating its receptor MET. HGF-induced entrectinib resistance was reversed by the active-HGF-specific macrocyclic peptide HiP-8 and the MET kinase inhibitor capmatinib in vitro. In addition, HGF-producing fibroblasts promoted entrectinib resistance in vitro (culture model) and in vivo (subcutaneous tumor model). The use of capmatinib circumvented entrectinib resistance in a subcutaneous tumor model inoculated with KM12SM and HGF-producing fibroblasts. CONCLUSION: Our findings suggest that growth factors in the tumor microenvironment, such as HGF, may induce resistance to entrectinib in tumors with NTRK1 or ROS1 rearrangements. Our results further suggest that optimally co-administering inhibitors of resistance-inducing growth factors may maximize the therapeutic efficacy of entrectinib.

Methylation of Tumor Suppressive miRNAs in Plasma from Patients With Pancreaticobiliary Diseases.

BACKGROUND/AIM: We previously reported the usefulness of aberrant methylation of tumor suppressive miRNAs in bile to discriminate pancreaticobiliary cancers (PBCs) from benign pancreaticobiliary diseases (BD). Here we performed a methylation analysis of plasma miRNAs to identify miRNAs specific for PBCs. PATIENTS AND METHODS: Plasma was collected from 80 patients with pancreatic cancer (PC); 18 with biliary tract cancer (BTC) and 28 with BD. Sequences encoding 3 tumor suppressive miRNAs (miR-200a, -200b, and -1247) were PCR amplified and sequenced, and their methylation rates were determined. RESULTS: The methylation rate of miR-1247 was significantly higher in patients with BTC than in those with BD, and tended to be higher in patients with PC than in those with BD. Furthermore, it was significantly higher in three patients with stages I/II BTC than in those with BD. CONCLUSION: Methylation of miR-1247 in plasma may be useful to distinguish BTC from BD.

Inhibition of EGFR and MEK surmounts entrectinib resistance in a brain metastasis model of NTRK1-rearranged tumor cells.

Tropomyosin receptor kinase (TRK) inhibitors have demonstrated histology-agnostic efficacy in patients with neurotrophic receptor tyrosine kinase (NTRK) gene fusion. Although responses to TRK inhibitors can be dramatic and durable, duration of response may eventually be limited by acquired resistance via several mechanisms, including resistance mutations such as NTRK1-G595R. Repotrectinib is a second-generation TRK inhibitor, which is active against NTRK1-G595R. However, its efficacy against entrectinib-resistant tumors has not been fully elucidated. In the present study, we established entrectinib-resistant tumor cells (M3B) in a brain metastasis model inoculated with NTRK1-rearranged KM12SM cells and examined the sensitivity of M3B cells to repotrectinib. While M3B cells harbored the NTRK1-G595R mutation, they were unexpectedly resistant to repotrectinib. The resistance was due to extracellular signal-regulated kinase (ERK) reactivation partially mediated by epidermal growth factor receptor (EGFR) activation. We further demonstrate that the triplet combination of repotrectinib, EGFR inhibitor, and MEK inhibitor could sensitize M3B cells in vitro as well as in a brain metastasis model. These results indicate that resistant mutations, such as NTRK1-G595R, and alternative pathway activation, such as ERK activation, could simultaneously occur in entrectinib-resistant tumors, thereby causing resistance to second-generation inhibitor repotrectinib. These findings highlight the importance of intensive examinations to identify resistance mechanisms and application of the appropriate combination treatment to circumvent the resistance.

STAT3 inhibition suppresses adaptive survival of ALK-rearranged lung cancer cells through transcriptional modulation of apoptosis.

Patients with advanced anaplastic lymphoma kinase (ALK)-rearranged non-small cell lung cancer who are prescribed ALK-tyrosine kinase inhibitors (ALK-TKIs) rarely have complete responses, with residual tumors relapsing as heterogeneous resistant phenotypes. Herein, we investigated new therapeutic strategies to reduce and eliminate residual tumors in the early treatment phase. Functional genomic screening using small guide RNA libraries showed that treatment-induced adaptive survival of ALK-rearranged lung cancer cells was predominantly dependent on STAT3 activity upon ALK inhibition. STAT3 inhibition effectively suppressed the adaptive survival of ALK-rearranged lung cancer cells by enhancing ALK inhibition-induced apoptosis. The combined effects were characterized by treatment-induced STAT3 dependence and transcriptional regulation of anti-apoptotic factor BCL-XL. In xenograft study, the combination of YHO-1701 (STAT3 inhibitor) and alectinib significantly suppressed tumor regrowth after treatment cessation with near tumor remission compared with alectinib alone. Hence, this study provides new insights into combined therapeutic strategies for patients with ALK-rearranged lung cancer.

Mediastinal Malignant Melanoma Markedly Shrinking in Response to Nivolumab.

Primary malignant melanoma (MM) of the mediastinum is rare, and there is a lack of consensus regarding the preferred treatment because non-cutaneous MM demonstrates an inferior response to systemic therapy. Herein, we describe the case of a 73-year-old man with MM of the anterior mediastinum with multiple liver metastases. Even though the size of lesions increased rapidly following diagnosis, nivolumab monotherapy caused remarkable tumor shrinkage. This is the first report of mediastinal MM showing a significant response to nivolumab. We, therefore, suggest that immunotherapy may be one of the treatment options for primary mediastinal MM.

Severe Skin Toxicity Caused by Sequential Anti-PD-1 Antibody and Alectinib in Non-small-cell Lung Cancer: A Report of Two Cases and a Literature Review.

Immune checkpoint inhibitors (ICIs) have demonstrated marked efficacy in some cancer patients, but they may cause various severe immune-related adverse events. Alectinib is a second-generation anaplastic lymphoma kinase (ALK)-tyrosine kinase inhibitor (TKI) approved for ALK-rearranged non-small-cell lung cancer (NSCLC). Alectinib is said to be safer than other TKIs. We conducted an investigator-initiated trial of alectinib, which also has RET kinase-inhibitory activity, against RET-rearranged NSCLC. Two RET-rearranged NSCLC patients experienced severe skin toxicity with alectinib after first undergoing anti-PD-1 antibody treatment with an ICI. These findings suggest that we should carefully follow patients for adverse effects of targeted drugs following ICI treatment.

A phase I/II study of osimertinib in EGFR exon 20 insertion mutation-positive non-small cell lung cancer.

OBJECTIVES: Several preclinical data proposed a potential efficacy of osimertinib, a third-generation EGFR tyrosine kinase inhibitor, for EGFR exon 20 insertion (EGFR ex20ins)-positive non-small cell lung cancer (NSCLC). However, reported case series and a retrospective study proposed controversial efficacy. The efficacy of osimertinib in EGFR ex20ins-positive NSCLC have not been well evaluated in prospective clinical trials. In this study, we performed a prospective, single-arm, multi-center, open-label, non-randomized phase I/II study to evaluate efficacy of osimertinib for EGFR ex20ins-positive NSCLC. MATERIALS AND METHODS: From August 2018 to January 2020, 14 NSCLC patients with EGFR ex20ins were enrolled, of whom 2 were excluded because they did not meet the inclusion criteria. Efficacy and safety of 80 mg osimertinib were evaluated. In addition, we performed a translational exploratory study to clarify the association of mutation type-specific drug sensitivity, osimertinib pharmacokinetic data, and clinical efficacy. RESULTS: Of the evaluated patients, none experienced objective response, 7 experienced stable disease (58.3%), and 5 experienced disease progression (41.7%). The median progression free survival (PFS) was 3.8 months, and the median overall survival was 15.8 months. Interestingly, the exploratory study demonstrated statistically significant positive correlation between plasma osimertinib concentration/in vitro IC50 ratio and PFS (R = 0.9912, P = 0.0001), highlighting the mutation type-specific concentration-dependent efficacy of osimertinib for EGFR ex20ins-positive NSCLC. CONCLUSIONS: Regular dose, 80 mg/day, of osimertinib has limited clinical activity in NSCLC patients with EGFR ex20ins. The translational study proposed the potential efficacy of higher dose osimertinib in a subgroup of EGFR ex20ins-positive NSCLC.

An analytical survey of benzotriazole UV stabilizers in plastic products and their endocrine-disrupting potential via human estrogen and androgen receptors.

Benzotriazole UV stabilizers (BUVSs) are added to various materials to prevent damage from UV-irradiation. Recently, there has been great concern regarding the endocrine-disrupting effects of exposure to microplastic-derivative BUVSs in particular. In this study, we measured the concentrations of nine representative BUVSs in the plastic bottle caps of 10 beverages, 4 food packages, and 4 plastic shopping bags purchased from Japanese grocery stores by GC-MS analysis, and found that eight BUVSs, except for 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-2H-benzotriazole (UV-320), were detected from these plastic products. In particular, 2-(2-hydroxy-5-methylphenyl) benzotriazole (UV-P) and 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole (UV-326) were detected from all the bottle caps at concentrations in the order of ng/g. In addition, we characterized the agonistic and/or antagonistic activities against human estrogen receptors (ERα/ß) and androgen receptor (AR) of 13 BUVSs. Results revealed that, among the 13 BUVSs, UV-P, 2-(5-tert-butyl-2-hydroxyphenyl) benzotriazole (UV-PS), 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole (UV-090) and 2-(2-hydroxy-5-tert-octylphenyl)-benzotriazole (UV-329) showed ERα and/or ERß agonistic activity, with UV-P being the most potent based on these assays. On the other hand, UV-320 and 2-(3-s-butyl-5-tert-butyl-2-hydroxyphenyl) benzotriazole (UV-350) showed both ERα and ERß antagonistic activities, and 2-(3,5-di-tert-amyl-2-hydroxylphenyl) benzotriazole (UV-328) and UV-329 acted as ERß antagonists. In the AR assay, UV-P and 2-(3-allyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole (UV-9) showed AR antagonistic activity although none of the test compounds showed AR agonistic activity. Taken together, our findings suggest that a series of BUVSs are present in our environments via plastic materials and several of these compounds possess endocrine-disrupting potential, such as ERα/ß agonistic and/or antagonistic activity and AR antagonistic activity. UV-P and its structurally similar compounds, in particular, appear to be a cause for concern.

Trametinib overcomes KRAS-G12V-induced osimertinib resistance in a leptomeningeal carcinomatosis model of EGFR-mutant lung cancer.

Leptomeningeal carcinomatosis (LMC) occurs frequently in non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations and is associated with acquired resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs). However, the mechanism by which LMC acquires resistance to osimertinib, a third-generation EGFR-TKI, is unclear. In this study, we elucidated the resistance mechanism and searched for a novel therapeutic strategy. We induced osimertinib resistance in a mouse model of LMC using an EGFR-mutant NSCLC cell line (PC9) via continuous oral osimertinib treatment and administration of established resistant cells and examined the resistance mechanism using next-generation sequencing. We detected the Kirsten rat sarcoma (KRAS)-G12V mutation in resistant cells, which retained the EGFR exon 19 deletion. Experiments involving KRAS knockdown in resistant cells and KRAS-G12V overexpression in parental cells revealed the involvement of KRAS-G12V in osimertinib resistance. Cotreatment with trametinib (a MEK inhibitor) and osimertinib resensitized the cells to osimertinib. Furthermore, in the mouse model of LMC with resistant cells, combined osimertinib and trametinib treatment successfully controlled LMC progression. These findings suggest a potential novel therapy against KRAS-G12V-harboring osimertinib-resistant LMC in EGFR-mutant NSCLC.

Multi-institutional survey of cancer disparities in disabled patients in the region of northwestern Japan.

BACKGROUND: Potential disparities between cancer patients with and without disabilities remained to be validate in Japan. METHODS: We surveyed retrospective data on hospital cancer registration as well as information on disability certificates obtained through the Hokushin Ganpro database. In total, 93,545 cancer patients in 10 principal hospitals covering the region of northwestern Japan were registered with the Hokushin Ganpro database between 2010 and 2015. The database included the following data: diagnosis date, cancer type, staging, treatment, cancer detection process, and possession of a disability certificate. RESULTS: We found that 2983 patients, which accounted for 3.2% of the total patients, had disabilities. No significant differences in gender, age at diagnosis, cancer stage distribution, and cancer incidence rates were observed between the disabled and non-disabled patients. Even though the proportion of early-stage cancer among disabled patients differed only slightly from that in non-disabled patients, early-stage cancer was more frequently diagnosed in patients with disabilities during their regular hospital visits than in those without disabilities, who had more opportunity for early cancer detection during cancer screening. According to in-house data reflecting treatment period and process from a single hospital, all 16 disabled patients treated with chemotherapy completed the treatment until disease progression or end of predetermined cycles. CONCLUSION: These results indicate that deep disparities between cancer patients with and without disabilities are not apparent and that the disabled patients in the region of northwestern Japan receive appropriate hospital follow-up.

Phase 1/2 study of alectinib in RET-rearranged previously-treated non-small cell lung cancer (ALL-RET).

BACKGROUND: Rearranged during transfection (RET) rearrangements occur in 1-2% of non-small cell lung cancers (NSCLCs). Alectinib administered at doses of 300 mg and 600 mg twice daily (BID) is approved for. ALK: rearranged NSCLC in Japan and other countries, respectively. Since alectinib has activity against RET, we conducted a phase (P) 1/2 study of alectinib to determine its activity in Japanese patients with. RET: rearranged NSCLC. METHODS: This study was a single-arm, open-label, multi-institutional P1/2 trial. Previously treated patients with RET-rearranged NSCLC, screened by nation-wide network (LC-SCRUM-Japan), were recruited. In P1, alectinib (600 or 450 mg BID) was administered following a 3+3 design and its safety was assessed. During P2, alectinib was administered at the recommended dose (RD) determined in P1. The primary endpoint was the objective response rate (ORR) in RET inhibitor-naïve patients treated with the RD of alectinib. RESULTS: Thirty-four patients were administered alectinib. In cohort 1 (600 mg BID) of P1, we observed 5 dose-limiting toxicities (DLTs), including grade 3 rash and thromboembolic event, in 3 of 6 patients. In cohort 2 (450 mg BID), we observed no DLTs in 3 patients. Pharmacokinetic analysis revealed that AUC0-10 to 600 mg BID was higher than that previously reported in global trials. We determined 450 mg BID as the RD for P2. In 25 RET inhibitor-naïve patients, one achieved an objective response (4%) and 13 achieved disease control at 8 weeks (52%). The median progression-free survival (PFS) was 3.4 months (95% CI, 2.0-5.4), while the median overall survival was 19.0 months (5.4-NE). We observed grade 3 adverse events (AEs) (4%) including pneumonitis in P2. CONCLUSIONS: Alectinib exerts limited activity against RET-rearranged NSCLC. Further investigation to elucidate the mechanisms underlying sensitivity and resistance of RET inhibitors is required to improve outcomes for these patients.

Multiple Malignant Lymphomas of the Bile Duct Developing after Spontaneous Regression of an Autoimmune Pancreatitis-like Mass.

We herein report a 67-year-old woman with malignant lymphomas of the bile duct that developed after regression of a pancreatic head mass. Computed tomography suggested the mass was pancreatic head cancer. Endoscopic ultrasonography showed a low-echoic mass with hyperechoic strands resembling autoimmune pancreatitis. Her serum IgG4 concentration was elevated to 674 mg/dL. After the pancreatic head mass spontaneously diminished, three masses were detected in the common bile duct. A biopsy of the major papilla revealed high-grade B-cell lymphoma with MYC, BCL2 and/or BCL6 rearrangement. Systemic chemotherapy with rituximab plus etoposide, prednisolone, vincristine, cyclophosphamide and doxorubicin resulted in complete remission.

Proteasome Inhibition Overcomes ALK-TKI Resistance in ALK-Rearranged/TP53-Mutant NSCLC via Noxa Expression.

PURPOSE: In ALK-rearranged non-small cell lung cancer (NSCLC), impacts of concomitant genetic alterations on targeted therapies with ALK-tyrosine kinase inhibitors (ALK-TKI) are not yet well understood. Here, we investigated genetic alterations related to ALK-TKI resistance using clinico-genomic data and explored effective therapies to overcome the resistance in preclinical models through the identification of underlying molecular mechanisms. EXPERIMENTAL DESIGN: We used integrated clinical and next-generation sequencing data generated in a nationwide lung cancer genome screening project (LC-SCRUM-Japan). ALK-rearranged NSCLC cell lines expressing wild-type or mutant TP53 were used to evaluate cellular apoptosis induced by ALK-TKIs. RESULTS: In 90 patients with ALK-rearranged NSCLC who were treated with a selective ALK-TKI, alectinib, TP53 comutated patients showed significantly worse progression-free survival (PFS) than TP53 wild-type patients [median PFS, 11.7 months (95% confidence interval, CI, 6.3-not reached, NR) vs. NR (23.6-NR); P = 0.0008; HR, 0.33 (95% CI, 0.17-0.65)]. ALK-rearranged NSCLC cell lines that lost p53 function were resistant to alectinib-induced apoptosis, but a proteasome inhibitior, ixazomib, markedly induced apoptosis in the alectinib-treated cells by increasing the expression of a proapoptotic protein, Noxa, which bound to an antiapoptotic protein, Mcl-1. In subcutaneous tumor models, combination of ixazomib and alectinib prominently induced tumor regression and apoptosis even though the tumors were generated from ALK-rearranged NSCLC cells with nonfunctional p53. CONCLUSIONS: These clinical and preclinical results indicate concomitant TP53 mutations reduce the efficacy of alectinib for ALK-rearranged NSCLC and the combined use of a proteasome inhibitor with alectinib is a promising therapy for ALK-rearranged/TP53-mutated NSCLC.

Resminostat, a histone deacetylase inhibitor, circumvents tolerance to EGFR inhibitors in EGFR-mutated lung cancer cells with BIM deletion polymorphism.

Drug-tolerant cells are mediators of acquired resistance. BIM-intron2 deletion polymorphism (BIM-del) is one of the mechanisms underlying the resistance to epidermal growth factor tyrosine kinase inhibitor (EGFR-TKI)-mediated apoptosis that induces drug tolerance. Here, we investigated whether resminostat, a histone deacetylase inhibitor, circumvents BIM-del-associated apoptosis resistance. The human EGFR-mutated non-small cell lung cancer (NSCLC) cell line PC-9 and its homozygous BIM-del-positive variant (PC-9 BIMi2- / -), established by editing with zinc finger nuclease, were used. In comparison with PC-9 cells, PC-9 BIMi2- / - cells were less sensitive to apoptosis mediated by EGFR-TKIs such as gefitinib and osimertinib. The combined use of resminostat and an EGFR-TKI preferentially induced the expression of the pro-apoptotic BIM transcript containing exon 4 rather than that containing exon 3, increased the level of pro-apoptotic BIM protein (BIMEL), and stimulated apoptosis in vitro. In a subcutaneous tumor model derived from PC-9 BIMi2- / - cells, gefitinib monotherapy decreased tumor size but retained residual lesions, indicative of the presence of tolerant cells in tumors. The combined use of resminostat and gefitinib increased BIMEL protein level and induced apoptosis, subsequently leading to the remarkable shrinkage of tumor. These findings suggest the potential of resminostat to circumvent tolerance to EGFR-TKIs associated with BIM deletion polymorphism. J. Med. Invest. 67 : 343-350, August, 2020.