Tazemetostat synergistically combats multidrug resistance by the unique triple inhibition of ABCB1, ABCC1, and ABCG2 efflux transporters in vitro and ex vivo.

ATP-binding cassette (ABC) drug efflux transporters and drug metabolizing enzymes play crucial roles in pharmacokinetic drug-drug interactions and multidrug tumor resistance (MDR). Tazemetostat (EPZ-6438, Tazverik) is a novel epigenetic drug that has been recently approved for the therapy of advanced epithelioid sarcoma and follicular lymphoma. Additionally, this medication is currently being clinically tested to treat several other cancers such as non-small cell lung cancer (NSCLC). This study aimed to investigate the inhibitory effects of tazemetostat on selected ABC transporters/cytochrome P450 3A4 (CYP3A4) enzyme to comprehensively explore its role in MDR. First, our accumulation and molecular docking studies showed that tazemetostat is a unique triple inhibitor of ABCB1, ABCC1, and ABCG2 transporters. In contrast, tazemetostat exhibited only low level of interaction with the CYP3A4 isozyme. Drug combination assays confirmed that tazemetostat is a multipotent MDR modulator able to synergize with various conventional chemotherapeutics in vitro. Subsequent caspase activity assays and microscopic staining of apoptotic nuclei proved that the effective induction of apoptosis is behind the observed synergies. Notably, a potent MDR-modulatory capacity of tazemetostat was recorded in primary ex vivo NSCLC explants generated from patients' biopsies. On the contrary, its possible position of pharmacokinetic MDR's victim was excluded in comparative proliferation assays. Finally, tested drug has not been identified as an inducer of resistant phenotype in NSCLC cell lines. In conclusion, we demonstrated that tazemetostat is a unique multispecific chemosensitizer, which has strong potential to overcome limitations seen in the era of traditional MDR modulators.

Encorafenib Acts as a Dual-Activity Chemosensitizer through Its Inhibitory Effect on ABCC1 Transporter In Vitro and Ex Vivo.

Encorafenib (LGX818, trade name Braftovi), a novel BRAF inhibitor, has been approved for the treatment of melanoma and colorectal cancer. In the present work, we evaluated encorafenib's possible antagonistic effects on the pharmacokinetic mechanisms of multidrug resistance (MDR), as well as its perpetrator role in drug interactions. Firstly, encorafenib potently inhibited the efflux function of the ABCC1 transporter in drug accumulation assays, while moderate and null interaction levels were recorded for ABCB1 and ABCG2, respectively. In contrast, the mRNA expression levels of all the tested transporters were not altered by encorafenib. In the drug combination studies, we found that daunorubicin and topotecan resistances were synergistically attenuated by the encorafenib-mediated interaction in A431-ABCC1 cells. Notably, further experiments in ex vivo patient-derived explants confirmed the MDR-modulating ability of encorafenib. Advantageously, the overexpression of tested drug efflux transporters failed to hinder the antiproliferative activity of encorafenib. In addition, no significant modulation of the CYP3A4 enzyme's activity by encorafenib was observed. In conclusion, our work indicated that encorafenib can act as an effective chemosensitizer targeting the ABCC1-induced MDR. Our in vitro and ex vivo data might provide valuable information for designing the novel effective scheme applicable in the clinical pharmacotherapy of BRAF-mutated/ABCC1-expressing tumors.

Talazoparib Does Not Interact with ABCB1 Transporter or Cytochrome P450s, but Modulates Multidrug Resistance Mediated by ABCC1 and ABCG2: An in Vitro and Ex Vivo Study.

Talazoparib (Talzenna) is a novel poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitor that is clinically used for the therapy of breast cancer. Furthermore, the drug has shown antitumor activity against different cancer types, including non-small cell lung cancer (NSCLC). In this work, we investigated the possible inhibitory interactions of talazoparib toward selected ATP-binding cassette (ABC) drug efflux transporters and cytochrome P450 biotransformation enzymes (CYPs) and evaluated its position in multidrug resistance (MDR). In accumulation studies, talazoparib interacted with the ABCC1 and ABCG2 transporters, but there were no significant effects on ABCB1. Furthermore, incubation assays revealed a negligible capacity of the tested drug to inhibit clinically relevant CYPs. In in vitro drug combination experiments, talazoparib synergistically reversed daunorubicin and mitoxantrone resistance in cells with ABCC1 and ABCG2 expression, respectively. Importantly, the position of an effective MDR modulator was further confirmed in drug combinations performed in ex vivo NSCLC patients-derived explants, whereas the possible victim role was refuted in comparative proliferation experiments. In addition, talazoparib had no significant effects on the mRNA-level expressions of MDR-related ABC transporters in the MCF-7 cellular model. In summary, our study presents a comprehensive overview on the pharmacokinetic drug-drug interactions (DDI) profile of talazoparib. Moreover, we introduced talazoparib as an efficient MDR antagonist.

Sonidegib potentiates the cancer cells' sensitivity to cytostatic agents by functional inhibition of ABCB1 and ABCG2 in vitro and ex vivo.

Sonidegib (LDE-225) is a Hedgehog pathway inhibitor used for the therapy of basal cell carcinoma. In addition, the drug is a subject of clinical trials for the treatment of other solid tumors including non-small cell lung cancer (NSCLC). In this study, we explored the potential of sonidegib to act as a perpetrator of drug-drug interactions (DDIs) and modulator of transporter- and enzyme-mediated multidrug resistance (MDR). First, we found that transport functions of ABCB1 and ABCG2 were effectively inhibited by sonidegib in accumulation studies. In contrast, the drug did not cause fluctuations in mRNA levels of tested efflux transporters. In drug combination assays, sonidegib synergistically enhanced the cytotoxicity of daunorubicin and mitoxantrone in ABCB1- and ABCG2-overexpressing cells, respectively. Notably, similar phenomena were also observed in explant tumor cultures derived from NSCLC-suffering patients. In addition, the anticancer effects of sonidegib were not hampered by the expression of the ABC transporters associated with MDR. Last, sonidegib had no significant influence on the activity of CYP3A4 isoform in vitro. In summary, our work suggests that sonidegib can be considered a potential perpetrator of clinical DDIs on ABCB1 and ABCG2. After in vivo evaluation, its chemosensitizing properties might be projected into efficient and safe treatment regimen for the clinical management of NSCLC patients with high ABCB1/ABCG2 expression.

Tepotinib Inhibits Several Drug Efflux Transporters and Biotransformation Enzymes: The Role in Drug-Drug Interactions and Targeting Cytostatic Resistance In Vitro and Ex Vivo.

Tepotinib is a novel tyrosine kinase inhibitor recently approved for the treatment of non-small cell lung cancer (NSCLC). In this study, we evaluated the tepotinib's potential to perpetrate pharmacokinetic drug interactions and modulate multidrug resistance (MDR). Accumulation studies showed that tepotinib potently inhibits ABCB1 and ABCG2 efflux transporters, which was confirmed by molecular docking. In addition, tepotinib inhibited several recombinant cytochrome P450 (CYP) isoforms with varying potency. In subsequent drug combination experiments, tepotinib synergistically reversed daunorubicin and mitoxantrone resistance in cells with ABCB1 and ABCG2 overexpression, respectively. Remarkably, MDR-modulatory properties were confirmed in ex vivo explants derived from NSCLC patients. Furthermore, we demonstrated that anticancer effect of tepotinib is not influenced by the presence of ABC transporters associated with MDR, although monolayer transport assays designated it as ABCB1 substrate. Finally, tested drug was observed to have negligible effect on the expression of clinically relevant drug efflux transporters and CYP enzymes. In conclusion, our findings provide complex overview on the tepotinib's drug interaction profile and suggest a promising novel therapeutic strategy for future clinical investigations.

Dieulafoys jejunal lesion as a source of lifethreating bleeding.

Dieulafoy`s lesion is a rare condition characterized by bleeding into gastrointestinal tract from minimaly eroded submucous artery. Mostly is localized in stomach in elderly polymorbid men, but can occure in entire gastrointestinal tract, in both sexes, in every age. It should be thought off as one of possible causes of obscure bleeding. It is often massive, requiring fast diagnostics, treatment and multidisciplinary approach. The case report discusses patient with recurrent hemodynamicaly significant bleeding into jejunum. It pointed to combined diagnostic approach using both endoscopy and angiography. After failing endoscopically and angiografically due to hemodynamic instability, surgical intervention took place. Precise Dieulafoy`s lesion diagnosis has been determined eventually on histologic section. Diagnostic and therapeutic approach should be individual taking patient´s condition and capabilities of department into consideration. Surgical intervention remains golden standard when hemodynamic instability occures or when endoscopy and angiography fail.

The Time Between Chemoradiation and Surgery for Rectal Carcinoma Negatively Influences Mesorectal Excision Quality.

Total mesorectal excision quality (TMEq) is a prognostic factor associated with local recurrence in rectal adenocarcinoma. Neoadjuvant chemoradiotherapy (NCRT) reduces the risk of tumor recurrence, but may compromise TMEq. The time between NCRT and surgery (TTS) and how it influences TMEq and tumor control were evaluated. In prospective registry, 236 patients after NCRT and TME were analyzed. NCRT involved radiotherapy with 45 Gy to the pelvis, plus tumor boost dose 5.4 Gy with concurrent 5-fluorouracil infusion. NCRT was followed by TME after 9 weeks on average (median 9.4 ± SD 2.5). TMEq was parametrically analyzed by standard three-grade system. With median follow-up of 47.5 months, 3-year overall survival (OS) was 83.8%, disease-free survival (DFS) was 77.7%, and 6.4% was the rate of local recurrence (LR). TTS was not associated with OS, DFS, or LR. TMEq was found to be associated with LR in univariate analysis, but not in multivariate, where pathological tumor stage and resection margins remained dominant predictors. TMEq was negatively influenced by inferior location of the tumor, longer TTS, higher tumor and nodal stage, presence of tumor perforation, perineural invasion, and close/positive resection margins. Nonetheless, TTS remained a strong predictor of TMEq in multivariate analyses. TTS was proven to be an independent predictor of TMEq. With longer TTS, fewer complete TME with intact mesorectal plane were observed. However, TTS was not associated with survival deterioration or tumor recurrence. These were negatively influenced by other factors interfering with TMEq, especially by pathological tumor stage and resection margins.

[Predictive diagnostics of gastric cancer in 2018]. / Prediktivní diagnostika adenokarcinomu zaludku - stav v roce 2018.

Anti-HER2 monoclonal antibody trastuzumab remains the only targeted therapy of gastric carcinoma based on histopathological predictive diagnostics used in current routine clinical practice. In the Czech Republic only the adenocarcinomas with HER2 immunohistochemical score of 3+, together with HER2 amplification detected with in situ hybridization are indicated for treatment with trastuzumab. There has been recent progress in our understanding of the molecular biology of gastric cancer, the role of its tumor microenvironment and vascular supply points to PD-1/PD-L1 and VEGFR2 as possible future targets of targeted therapy. Unfortunately, the interpretation of the results of pharmacological studies, as well as establishing new algorithms of predictive diagnostics are complicated by insufficient molecular stratification of tumors enrolled in the study groups.

[Identification of an optimal algorithm for effective diagnostics of non-small cell lung cancer with ALK gene rearrangement - implementation of the method and practical experiences with routine diagnostics]. / Stanovení optimálního vysetrovacího algoritmu pro efektivní vyhledávání nemalobunecných karcinomu plic s prestavbou genu ALK - zavedení metodiky a praktické zkusenosti z rutinního vysetrování.

The aim of the retrospective part of the study was a) to select an optimal clone of immunohistochemical (IHC) antibody against the ALK protein with specificity and sensitivity high enough to use this antibody as a screening method for selecting non-small cell lung cancer (NSCLC) cases for fluorescence in situ hybridization (FISH) testing of ALK gene rearrangement and b) to determine the diagnostic yield of "small" biopsies i.e. endobronchial, transbronchial and transthoracic biopsies and cytoblocks for ALK gene rearrangement testing. The best IHC method of ALK protein detection (clone D5F3, dilution 1:100, Cell Signaling Technology, Danvers, MA, USA) was then verified in prospective routine testing of patients with NSCLC. ALK status was correlated with tumor morphology and clinical data. In the retrospective part of the study, 170 EGFR-nonmutated cases of NSCLC were IHC and FISH tested. In the prospective part, 557 cases of NSCLC were tested by IHC and 76 by FISH. There were 8/154 (5.2%) cases with ALK gene rearrangement detected in the retrospective part and 24/557(4.3 %) in the prospective part. Sensitivity and specificity of the best IHC method were 100 % and 99 % in the retrospective part and 100 % and 80 % in the prospective part. The diagnostic yield of "small" biopsies was between 74 - 80 % retrospectively, depending on IHC variant, and 88 % prospectively. No case with ALK gene rearrangement detected prospectively had EGFR mutation. A high diagnostic yield confirms that ALK status testing can be used in this type of specimen. A prevalence of 5.2 % in the retrospective part (EGFR-nonmutated cases) and 4.3 % in the prospective part (without known EGFR mutation status), tumor morphology (solid and acinar type, mucinous type or at least partial mucin production (extra- and/or intracellular) as well as lower average age and male/female ratio of patients with ALK positive tumors in the prospective part (57.5 y vs. 65.2 y, 8 men and 16 women vs. 336 men and 197 women) are consistent with global data.

EGFR in triple negative breast carcinoma: significance of protein expression and high gene copy number.

BACKGROUND: As up to 60 % of triple negative breast carcinomas are reported to express EGFR, the receptor is a potential target for biological therapy. The exact role EGFR plays in triple negative breast carcinoma (TNBC) biology, however, remains uncertain. We aimed to discover associations between EGFR protein expression as well as gene copy number changes and clinico-pathologic TNBC characteristics. METHODS: We performed an immunohistochemical and dual in situ hybridization study on a set of 52 archive cases of pre-treatment TNBC in order to detect EGFR protein expression and EGFR gene copy number changes. Clinico-pathologic and follow up data were compared with EGFR status for determining possible links between EGFR and tumor characteristics and/or behavior. RESULTS: 88.5 % of our cases showed EGFR expression. We found no significant links between EGFR expression and tumor grade (p = 0.204), lymph node status (p = 0.514) or p53 status (p = 0.078). Though EGFR gene amplification (EGFR gene:chromosome 7 ratio 2) was rare (1.9 % of all cases), a high gene copy number ( 4 copies per cell) was observed in 15.4 % of all cases. High EGFR gene copy number appeared to be more common in non-ductal, special-type carcinomas than in ductal carcinomas. Neither EGFR expression nor EGFR gene copy number was associated with event-free survival. CONCLUSION: EGFR changes do not appear to be associated with markers of aggressive behavior in TNBC. Further studies with much larger sample sizes are essential in understanding the role EGFR plays in TNBC biology in order to identify the patients that could benefit from EGFR targeted therapy.

[Hopes and pitfalls of the molecular classification of breast cancer]. / Nadeje a úskalí molekulární klasifikace karcinomu prsu.

Traditional histopathological diagnosis of breast cancer has been extended in recent years through the results of additional methods. Today, the results of the detection of hormone receptors, HER-2/neu, and Ki67 antigen are thus an integral part of the histopathological diagnosis. A critical factor for the success of these tests is the fulfillment of pre-analytical phase conditions - i.e. optimal fixation, as well as taking into account the heterogeneous nature of the neoplastic population. In addition to the above-mentioned markers - which have become a routine practice in recent years, there are many efforts to include the molecular characteristics of tumors both in tumor classification as well as in the prediction of results of cancer treatment. Most of the work is based on the use of gene expression profiles. On the basis of the detection of increased or decreased expression of a large number of genes, it is possible to find a set of multiple genes correlating with the biological behavior of the tumor. Using this approach, four basic subgroups of breast cancer have been identified - luminal, basal-like, HER-2 enriched and normal gland-like. Over the course of time, the number of molecular categories has expanded - originally a homogenous group of luminal cancers has been subclassified into the luminal A, B and C. Also within basal-like carcinomas additional subgroups have been identified. However, the results of studies dealing with the analysis of gene expression profiles suggest that our understanding of the biology of breast cancer is far from being complete. The individual categories are defined differently in various publications and thus the comparison of the results of these studies is very difficult. Another approach for the molecular classification of breast cancer is the immunohistochemical detection of various proteins used as a surrogate marker instead of the detection of the mRNA of individual genes. The advantage of this approach is the possibility to use even archive material, as well as much lower costs. On the other hand, its main limitation is the inability of parallel detection of thousands of markers, unlike in genomic profiling. The results of molecular classification are, however, not fundamentally surprising. The fact that breast cancer tumor stem cells can differentiate towards myoepithelial (or basal) and luminal cells has been known for a long time. These two lines of differentiation are - among others - characterized by differential expression of cytoskeletal proteins as well as of other molecules. These findings have been confirmed by the results of molecular studies - either those based on gene expression profiling or immunohistochemical ones. Research results in gene expression profiling have relatively quickly translated into clinical practice. At present, several commercially available certified tests serve as a complementary source of information for decisions about clinical treatment.

Comparison of immunohistochemistry, four in situ hybridization methods and quantitative polymerase chain reaction for the molecular diagnosis of HER2 status in gastric cancer: a study of 55 cases.

In the current study, the sensitivity and specificity of methods of HER2 status detection were studied in 55 patients presenting with gastric/gastroesophageal junction carcinoma (30 intestinal and 25 diffuse), in small biopsy (endoscopy; n=33) and resection specimens (n=22). The primary objective of the present study was to compare various methods for the assessment of HER2 status, with regards to the sensitivity and specificity of each method, as well as their concordance. In all cases, the status of HER2 was determined using immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), silver in situ hybridization (SISH), and quantitative polymerase chain reaction (qPCR). The concordance rate between IHC and ISH was 100% for IHC 0 and 3+. The concordance rate for IHC 1+ was 100% between IHC and SISH, and 92.9% between IHC and FISH. The concordance rate among different FISH methods was 100%, between FISH and SISH it was 96.2%, and between qPCR and ISH methods it was 88.5%. Thus, the results demonstrate that different in situ hybridization methods are comparable and that none were superior. Furthermore, the IHC and FISH methods were found to be comparable and the concordance rate was particularly good. qPCR analysis correlated well with the other methods and appears to be a possible alternative tool for detection of the HER2 status. However, the concordance rate of qPCR with other methods was identified to be lower in the diffuse carcinoma group of endoscopy biopsy specimens; therefore investigation of further cases is required.

Hepatic arterial infusion for biliary tract carcinoma: single-center experience.

AIM: The aim of the present study was to evaluate a single-center experience in hepatic arterial infusion (HAI) of patients with biliary tract carcinomas. PATIENTS AND METHODS: A retrospective analysis of 60 patients treated between 1997 and 2011 was performed. RESULTS: Most patients were treated with HAI of a combination of 5-fluorouracil, folinic acid and cisplatin. The response was not evaluable in most patients, predominantly because of prior surgical procedures. The median survival of all patients was 15.1 months (5-year survival=13%). The survival was significantly better in patients treated with radical surgery (median=50.1 months, 5-year survival=45%) or palliative surgery (median=22.5 months, 5-year survival=13%) compared to no surgery (median=7.6 months, 5-year survival=3%). CONCLUSION: The current data demonstrate the efficacy of HAI in patients with biliary tract carcinoma. HAI is a therapeutic method to be considered in patients with inoperable biliary tract carcinoma and no extrahepatic spread.

Calcific aortic valve stenosis: Immunohistochemical analysis of inflammatory infiltrate.

Calcific aortic valve disease is considered a form of atherosclerosis and, like the latter, possibly of inflammatory origin. The aim of our work was to study the pattern of cellular infiltrate in calcific aortic valve stenosis (CAS). Fifteen operatively excised calcified aortic valves were examined by histology and immunohistochemistry (CD20, CD79α, CD3, CD4, CD8, CD68, CD138, CD117, BJK, BJL, IgA, IgD, IgG, IgG4 and IgM). The findings revealed that in CAS, there were chronic inflammatory features with infiltrates comprising lymphocytes, polyclonal plasma cells, histiocytes and mast cells. In T-lymphocytes, CD4 prevailed over CD8. In B-lymphocytes, there was a slight preponderance of CD20 over CD79α. The BJL (lambda)-positive plasma cells prevailed over the BJK (kappa) ones. The CD138-positive plasma cells comprised 24% IgA-, 20% IgD-, 41% IgG- (including 11% of IgG4-) and 15% IgM-positive cells. CAS did not fulfill the criteria of the recently described clinicopathological entity IgG4-related sclerosing systemic disease. The inflammatory process was the same in both subsets of CAS - those with trileaflet (normally formed) valves and those with congenitally bicuspid valves.