Effect of thoracic cage width on surgery time and postoperative outcome in minimally invasive esophagectomy.

INTRODUCTION: Minimally invasive esophagectomy (MIE) for esophageal cancer is a complex procedure that reduces postoperative morbidity in comparison to open approach. In this study, thoracic cage width as a factor to predict surgical difficulty in MIE was evaluated. METHODS: All patients of our institution receiving either total MIE or robotic-assisted MIE (RAMIE) with intrathoracic anastomosis between February 2016 and April 2021 for esophageal cancer were included in this study. Right unilateral thoracic cage width on the level of vena azygos crossing the esophagus was measured by the horizontal distance between the esophagus and parietal pleura on preoperative computer tomography. Patients' data as well as operative and postoperative details were collected in a prospective database. Correlation between thoracic cage width with duration of the thoracic procedure and postoperative complication rates was analyzed. RESULTS: Overall, 313 patients were eligible for this study. Thoracic width on vena azygos level ranged from 85 to 149 mm with a mean of 116.5 mm. In univariate analysis, a small thoracic width significantly correlated with longer duration of the thoracic procedure (p = 0.014). In multivariate analysis, small thoracic width and neoadjuvant therapy were identified as independent factors for long duration of the thoracic procedure (p = 0.006). Regarding postoperative complications, thoracic cage width was a significant risk factor for occurrence of postoperative pneumonia in the multivariate analysis (p = 0.045). Dividing the cohort into two groups of patients with narrow (≤ 107 mm, 19.5%) and wide thoraces (≥ 108 mm, 80.5%), the thoracic procedure was significantly prolonged by 17 min (204 min vs. 221 min, p = 0.014). CONCLUSION: A small thoracic cage width is significantly correlated with longer operation time during thoracic phase of a MIE in Europe, which suggests increased surgical difficulty. Patients with small thoracic cage width may preferably be operated by MIE-experienced surgeons.

Extended lower paratracheal lymph node resection during esophagectomy for cancer - safety and necessity.

BACKGROUND: The ideal extent of lymphadenectomy (LAD) in esophageal oncological surgery is debated. There is no evidence for improved survival after standardized paratracheal lymph node resection performing oncological esophagectomy. Lymph nodes from the lower paratracheal station are not standardly resected during 2-field Ivor-Lewis esophagectomy for esophageal cancer. The objective of this study was to evaluate the impact of lower paratracheal lymph node (LPL) resection on perioperative outcome during esophagectomy for cancer and analyze its relevance. METHODS: Retrospectively, we identified 200 consecutive patients operated in our center for esophageal cancer from January 2017 - December 2019. Patients with and without lower paratracheal LAD were compared regarding demographic data, tumor characteristics, operative details, postoperative complications, tumor recurrence and overall survival. RESULTS: 103 out of 200 patients received lower paratracheal lymph node resection. On average, five lymph nodes were resected in the paratracheal region and cancer infiltration was found in two patients. Those two patients suffered from neuroendocrine carcinoma and melanoma respectively. Cases with lower paratracheal lymph node yield had significantly less overall complicated procedures (p = 0.026). Regarding overall survival and recurrence rate no significant difference could be detected between both groups (p = 0.168 and 0.371 respectively). CONCLUSION: The resection of lower paratracheal lymph nodes during esophagectomy remains debatable for distal squamous cell carcinoma or adenocarcinoma of the esophagus. Tumor infiltration was only found in rare cancer entities. Since resection can be performed safely, we recommend LPL resection on demand.

Robot-assisted minimally invasive thoraco-laparoscopic esophagectomy versus minimally invasive esophagectomy for resectable esophageal adenocarcinoma, a randomized controlled trial (ROBOT-2 trial).

BACKGROUND: For patients with esophageal adenocarcinoma or cancer of the gastroesophageal junction, radical esophagectomy with 2-field lymphadenectomy is the cornerstone of the multimodality treatment with curative intent. Both conventional minimally invasive esophagectomy (MIE) and robot assisted minimally invasive esophagectomy (RAMIE) were shown to be superior compared to open transthoracic esophagectomy considering postoperative complications. However, no randomized comparison exists between MIE and RAMIE in the Western World for patients with esophageal adenocarcinoma. METHODS: This is an investigator-initiated and investigator-driven multicenter randomized controlled parallel-group superiority trial. All adult patients (age ≥ 18 and ≤ 90 years) with histologically proven, surgically resectable (cT1-4a, N0-3, M0) esophageal adenocarcinoma of the intrathoracic esophagus or adenocarcinoma of the gastroesophageal junction and with European Clinical Oncology Group performance status 0, 1 or 2 will be assessed for eligibility and included after obtaining informed consent. Patients (n = 218) with resectable esophageal adenocarcinoma of the intrathoracic esophagus or adenocarcinoma of the gastroesophageal junction are randomized to either RAMIE (n = 109) or MIE (n = 109). The primary outcome of this study is the total number of resected abdominal and mediastinal lymph nodes specified per lymph node station. CONCLUSION: This is the first randomized controlled trial designed to compare RAMIE to MIE as surgical treatment for resectable esophageal adenocarcinoma or adenocarcinoma of the gastroesophageal junction in the Western World. The hypothesis of the proposed study is that RAMIE will result in a higher abdominal and mediastinal lymph node yield specified per station compared to conventional MIE. Short-term results and the primary endpoint (total number of resected abdominal and mediastinal lymph nodes per lymph node station) will be analyzed and published after discharge of the last randomized patient within this trial. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04306458 . Registered 13th March 2020, https://clinicaltrials.gov/ct2/show/NCT04306458; Date of first enrolment 18.01.2021; Target sample size 218; Recruitment status: Recruiting; Protocol version 2; Issue date 10.03.2020; Rev. 02.02.2021; Authors ET, PCvdS, PPG.

Minimally invasive esophagectomy: clinical evidence and surgical techniques.

BACKGROUND: Surgical esophagectomy plays a crucial role in the curative and palliative treatment of esophageal cancer. Thereby, minimally invasive esophagectomy (MIE) is increasingly applied all over the world. Combining minimal invasiveness with improved possibilities for meticulous dissection, robot-assisted minimal invasive esophagectomy (RAMIE) has been implemented in many centers. PURPOSE: This review focuses on the development of MIE as well as RAMIE and their value based on evidence in current literature. CONCLUSION: Although MIE and RAMIE are highly complex procedures, they can be performed safely with improved postoperative outcome and equal oncological results compared with open esophagectomy (OE). RAMIE offers additional advantages regarding surgical dissection, lymphadenectomy, and extended indications for advanced tumors.

Robot-assisted minimally invasive esophagectomy (RAMIE) compared to conventional minimally invasive esophagectomy (MIE) for esophageal cancer: a propensity-matched analysis.

Robot-assisted minimally invasive esophagectomy (RAMIE) is increasingly being applied as treatment for esophageal cancer. In this study, the results of 50 RAMIE procedures were compared with 50 conventional minimally invasive esophagectomy (MIE) operations, which had been the standard treatment for esophageal cancer prior to the robotic era. Between April 2016 and March 2018, data of 100 consecutive patients with esophageal carcinoma undergoing modified Ivor Lewis esophagectomy were prospectively collected. All operations were performed by the same surgeon using an identical intrathoracic anastomotic reconstruction technique with the same perioperative management and pain control regimen. Intra-operative and postoperative complications were graded according to definitions stated by the Esophagectomy Complications Consensus Group. Data analysis was carried out with and without propensity score matching. Baseline characteristics did not show significant differences between the RAMIE and MIE group. Propensity score matching of the initial group of 100 patients resulted in two equal groups of 40 patients for each surgical approach. In the RAMIE group, the median total lymph node yield was 27 (range 13-84) compared to 23 in the MIE group (range 11-48), P = 0.053. Median intensive care unit (ICU) stay was 1 day (range 1-43) in the RAMIE group compared to 2 days (range 1-17) in the MIE group (P = 0.029). The incidence of postoperative complications was not significantly different between the two groups (P = 0.581). In this propensity-matched study comparing RAMIE to MIE, ICU stay was significantly shorter in the RAMIE group. There was a trend in improved lymphadenectomy in RAMIE.

Innovative fully robotic 4-arm Ivor Lewis esophagectomy for esophageal cancer (RAMIE4).

Nowadays robotic surgery is established for abdominal and thoracic surgery. It has been shown that complex procedures are feasible using robotic systems, e.g., da Vinci Xi, with a huge benefit in precision. Different techniques for esophageal cancer surgery are reported; however, only a few robotic and partial robotic procedures are described. Therefore, a fully robotic (abdominal and thoracic) Ivor Lewis esophageal resection using four robotic arms-RAMIE4-the standard technique used for lower esophageal cancer, is presented in this paper. The technique shown in the video was performed successfully in 100 cases in 24 months. The reconstruction is performed with a gastric conduit pull-up and intrathoracic manually inserted 28-mm circular end-to-side stapled anastomosis. This video demonstrates the feasibility of RAMIE4 in the abdomen and thorax and reveals advantages of the robotic assistance.

Change from Hybrid to Fully Minimally Invasive and Robotic Esophagectomy is Possible without Compromises.

BACKGROUND: The incidence of esophageal carcinoma is increasing in the western world, and esophageal resection is the essential therapy. Several studies report advantages of minimally invasive esophagectomies (MIEs) versus conventional open procedures (OPs). The benefits of the use of fully MIE or robot-assisted MIE (RAMIE) compared with the hybrid approaches (laparoscopic gastric preparation and open transthoracic esophagectomy) remain unclear. METHODS: Between July 2015 and August 2017, the data of 75 patients with esophageal carcinoma were prospectively registered. Of the 75 patients, 25 treated with a hybrid MIE (hybrid), 25 with total MIE (MIE), and 25 with RAMIE. All patients were operated by the same specialized surgeon in our center with an identical anastomotic technique (circular stapler). RESULTS: The overall 30- and 90-day mortality rates were 0 and 1.33% (1/75), respectively. Total hospital stay (p = 0.262), intensive care unit stay (p = 0.079), number of resected lymph nodes (p = 0.863), and R status (p = 0.132) did not differ statistically between the groups. However, pneumonia and wound infections occurred significantly and more frequently in the hybrid group compared with the minimally invasive groups (MIE and RAMIE) (p = 0.046 and p = 0.003, respectively). CONCLUSION: Comparable results regarding morbidity and short-term outcome could be achieved in the MIE and RAMIE groups compared with the hybrid group. The data indicate that the learning curve is low in surgeons changing the technique form hybrid esophagectomy to fully MIE. Additionally, the total minimally invasive approaches seem to be associated with a low incidence of complications such as pneumonia and wound infections.

Preoperative endoscopic pyloric balloon dilatation decreases the rate of delayed gastric emptying after Ivor-Lewis esophagectomy.

Delayed gastric emptying (DGE) after Ivor-Lewis esophagectomy occurs postoperatively in up to 50% of the patients. This pyloric dysfunction can lead to severe secondary complications postoperatively such as early aspiration, pneumonia or may even have an impact on anastomotic healing and therefore leakage. Early detection of DGE is essential to prevent further complications. The common treatment postoperatively is endoscopic pyloric balloon dilatation (EPBD) after symptoms already occurred. In our work, we analyzed patients who received a preoperative EPBD during the routine restaging endoscopy and compared those patients to a control group to analyze if preoperative EPBD may prevent postoperative DGE and secondary additional complications. We performed a single-center retrospective analysis of 115 patients who received an Ivor-Lewis esophagectomy by the same surgeon between June 2015 and October 2017. Out of these 115 patients, 91 (79.1%) patients received EPBD preoperatively during the staging/restaging endoscopy (PDG, pyloric dilatation group). In 24 (20.9%) patients, preoperative EPBD was not performed due to stenotic esophageal tumors or logistic reasons (NDG, non-pyloric dilatation group). Data of the PDG and NDG group were compared regarding the rate of postoperative DGE as well as DGE and EPBD related complications. In total, 21 (18.3%) patients developed pyloric dysfunction requiring a total of 27 EPBD during follow-up. There were 12 (13.2%) patients in the PDG and 9 (37.5%) patients in the NDG (p = 0.014), respectively. DGE-related complications such as anastomotic leaks (p = 0.466), pulmonary complications (p = 0.466) and longer median hospital stay (p = 0.685) were more frequent in the NDG group; however this difference did not reach statistical significance. The success rate for postoperative EPBD with 20-mm balloons was lower (58.5%) compared to the usage of 30-mm balloons (93.3%). All pre- and postoperative EPBD were performed without any complications. Preoperative EPBD is feasible, safe and can be combined with restating endoscopy. It seems that preoperative EPBD reduces the incidence of DGE and can prevent the need for early postoperative endoscopic interventions. Our recommendation is therefore to perform an EPBD preoperatively when possible to reduce postoperative complications to a minimum. For postoperative EPBD, we recommend the use of the 30-mm balloon due to lower redilatation rates.

Drug-induced inhibition of phosphorylation of STAT5 overrides drug resistance in neoplastic mast cells.

Systemic mastocytosis (SM) is a mast cell (MC) neoplasm with complex pathology and a variable clinical course. In aggressive SM (ASM) and MC leukemia (MCL), responses to conventional drugs are poor and the prognosis is dismal. R763 is a multi-kinase inhibitor that blocks the activity of Aurora-kinase-A/B, ABL1, AKT and FLT3. We examined the effects of R763 on proliferation and survival of neoplastic MC. R763 produced dose-dependent inhibition of proliferation in the human MC lines HMC-1.1 (IC50 5-50 nM), HMC-1.2 (IC50 1-10 nM), ROSAKIT WT (IC50 1-10 nM), ROSAKIT D816V (IC50 50-500 nM) and MCPV-1.1 (IC50 100-1000 nM). Moreover, R763 induced growth inhibition in primary neoplastic MC in patients with ASM and MCL. Growth-inhibitory effects of R763 were accompanied by signs of apoptosis and a G2/M cell cycle arrest. R763 also inhibited phosphorylation of KIT, BTK, AKT and STAT5 in neoplastic MC. The most sensitive target appeared to be STAT5. In fact, tyrosine phosphorylation of STAT5 was inhibited by R763 at 10 nM. At this low concentration, R763 produced synergistic growth-inhibitory effects on neoplastic MC when combined with midostaurin or dasatinib. Together, R763 is a novel promising multi-kinase inhibitor that blocks STAT5 activation and thereby overrides drug-resistance in neoplastic MC.

Nilotinib-induced vasculopathy: identification of vascular endothelial cells as a primary target site.

The BCR/ABL1 inhibitor Nilotinib is increasingly used to treat patients with chronic myeloid leukemia (CML). Although otherwise well-tolerated, Nilotinib has been associated with the occurrence of progressive arterial occlusive disease (AOD). Our objective was to determine the exact frequency of AOD and examine in vitro and in vivo effects of Nilotinib and Imatinib on endothelial cells to explain AOD-development. In contrast to Imatinib, Nilotinib was found to upregulate pro-atherogenic adhesion-proteins (ICAM-1, E-selectin, VCAM-1) on human endothelial cells. Nilotinib also suppressed endothelial cell proliferation, migration and tube-formation and bound to a distinct set of target-kinases, relevant to angiogenesis and atherosclerosis, including angiopoietin receptor-1 TEK, ABL-2, JAK1 and MAP-kinases. Nilotinib and siRNA against ABL-2 also suppressed KDR expression. In addition, Nilotinib augmented atherosclerosis in ApoE-/- mice and blocked reperfusion and angiogenesis in a hindlimb-ischemia model of arterial occlusion, whereas Imatinib showed no comparable effects. Clinically overt AOD-events were found to accumulate over time in Nilotinib-treated patients. After a median observation-time of 2.0 years, the AOD-frequency was higher in these patients (29.4%) compared to risk factor- and age-matched controls (<5%). Together, Nilotinib exerts direct pro-atherogenic and anti-angiogenic effects on vascular endothelial cells, which may contribute to development of AOD in patients with CML.

Achalasia-an unnecessary long way to diagnosis.

Although achalasia presents with typical symptoms such as dysphagia, regurgitation, weight loss, and atypical chest pain, the time until first diagnosis often takes years and is frustrating for patients and nevertheless associated with high costs for the healthcare system. A total of 563 patients were interviewed with confirmed diagnosis of achalasia regarding their symptoms leading to diagnosis along with past clinical examinations and treatments. Included were patients who had undergone their medical investigations in Germany. Overall, 527 study subjects were included (male 46%, female 54%, mean age at time of interview 51 ± 14.8 years). Dysphagia was present in 86.7%, regurgitation in 82.9%, atypical chest pain in 79%, and weight loss in 58% of patients before diagnosis. On average, it took 25 months (Interquartile Range (IQR) 9-65) until confirmation of correct diagnosis of achalasia. Though, diagnosis was confirmed significantly quicker (35 months IQR 9-89 vs. 20 months IQR 8-53; p < 0.01) in the past 15 years. The majority (72.1%) was transferred to three or more specialists. Almost each patient underwent at least one esophagogastroduodenoscopy (94.2%) and one radiological assessment (89.3%). However, esophageal manometry was performed in 70.4% of patients only. The severity of symptoms was independent with regard to duration until first diagnosis (Eckardt score 7.14 ± 2.64 within 12 months vs. 7.29 ± 2.61 longer than 12 months; P = 0.544). Fifty-five percent of the patients primarily underwent endoscopic dilatation and 37% a surgical myotomy. Endoscopic dilatation was realized significantly faster compared to esophageal myotomy (1 month IQR 0-4 vs. 3 months IQR 1-11; p < 0.001). Although diagnosis of achalasia was significantly faster in the past 15 years, it still takes almost 2 years until the correct diagnosis of achalasia is confirmed. Alarming is the fact that although esophageal manometry is known as the gold standard to differentiate primary motility disorders, only three out of four patients had undergone this diagnostic pathway during their diagnostic work-up. Better education of medical professionals and broader utilization of highly sensitive diagnostic tools, such as high-resolution manometry, are strictly necessary in order to correctly diagnose affected patients and to offer therapy faster.

Proposed diagnostic criteria and classification of basophilic leukemias and related disorders.

Basophils form a distinct cell lineage within the hematopoietic cell family. In various myeloid neoplasms, including chronic myeloid leukemia, basophilia is frequently seen. Acute and chronic basophilic leukemias, albeit rare, have also been described. However, no generally accepted criteria and classification of basophilic leukemias have been presented to date. To address this unmet need, a series of Working Conferences and other meetings were organized between March 2015 and March 2016. The current article provides a summary of consensus statements from these meetings, together with proposed criteria to delineate acute basophilic leukemia (ABL) from chronic basophilic leukemia (CBL) and primary forms of the disease where no preceding myeloid malignancy is detected, from the more common 'secondary' variants. Moreover, the term hyperbasophilia (HB) is proposed for cases with a persistent peripheral basophil count ⩾1000 per µl of blood. This condition, HB, is highly indicative of the presence of an underlying myeloid neoplasm. Therefore, HB is an important checkpoint in the diagnostic algorithm and requires a detailed hematologic investigation. In these patients, an underlying myeloid malignancy is often found and is then labeled with the appendix -baso, whereas primary cases of ABL or CBL are very rare. The criteria and classification proposed in this article should facilitate the diagnosis and management of patients with unexplained basophilia and basophil neoplasms in routine practice, and in clinical studies.

IL-4 downregulates expression of the target receptor CD30 in neoplastic canine mast cells.

CD30 is a novel therapeutic target in human mast cell (MC) neoplasms. In this 'comparative oncology' study, we examined CD30 expression and regulation in neoplastic canine MC using a panel of immunomodulatory cytokines [interleukin-2 (IL-2), IL-4, IL-5, IL-6, IL-13 and stem cell factor (SCF)] and the canine mastocytoma cell lines NI-1 and C2. Of all cytokines tested IL-4 was found to downregulate expression of CD30 in NI-1 and C2 cells. We also found that the CD30-targeting antibody-conjugate brentuximab vedotin induces growth inhibition and apoptosis in both MC lines. Next, we asked whether IL-4-induced downregulation of CD30 interferes with brentuximab vedotin-effects. Indeed, pre-incubation of NI-1 cells with IL-4 decreased responsiveness towards brentuximab vedotin. To overcome IL-4-mediated resistance, we applied drug combinations and found that brentuximab vedotin synergizes with the Kit-targeting drugs masitinib and PKC412 in inhibiting growth of NI-1 and C2 cells. In summary, CD30 is a new marker and IL-4-regulated target in neoplastic canine MC.

Target interaction profiling of midostaurin and its metabolites in neoplastic mast cells predicts distinct effects on activation and growth.

Proteomic-based drug testing is an emerging approach to establish the clinical value and anti-neoplastic potential of multikinase inhibitors. The multikinase inhibitor midostaurin (PKC412) is a promising new agent used to treat patients with advanced systemic mastocytosis (SM). We examined the target interaction profiles and the mast cell (MC)-targeting effects of two pharmacologically relevant midostaurin metabolites, CGP52421 and CGP62221. All three compounds, midostaurin and the two metabolites, suppressed IgE-dependent histamine secretion in basophils and MC with reasonable IC(50) values. Midostaurin and CGP62221 also produced growth inhibition and dephosphorylation of KIT in the MC leukemia cell line HMC-1.2, whereas the second metabolite, CGP52421, which accumulates in vivo, showed no substantial effects. Chemical proteomic profiling and drug competition experiments revealed that midostaurin interacts with KIT and several additional kinase targets. The key downstream regulator FES was recognized by midostaurin and CGP62221, but not by CGP52421 in MC lysates, whereas the IgE receptor downstream target SYK was recognized by both metabolites. Together, our data show that the clinically relevant midostaurin metabolite CGP52421 inhibits IgE-dependent histamine release, but is a weak inhibitor of MC proliferation, which may have clinical implications and may explain why mediator-related symptoms improve in SM patients even when disease progression occurs.

Identification of bromodomain-containing protein-4 as a novel marker and epigenetic target in mast cell leukemia.

Advanced systemic mastocytosis (SM) is a life-threatening neoplasm characterized by uncontrolled growth and accumulation of neoplastic mast cells (MCs) in various organs and a poor survival. So far, no curative treatment concept has been developed for these patients. We identified the epigenetic reader bromodomain-containing protein-4 (BRD4) as novel drug target in aggressive SM (ASM) and MC leukemia (MCL). As assessed by immunohistochemistry and PCR, neoplastic MCs expressed substantial amounts of BRD4 in ASM and MCL. The human MCL lines HMC-1 and ROSA also expressed BRD4, and their proliferation was blocked by a BRD4-specific short hairpin RNA. Correspondingly, the BRD4-targeting drug JQ1 induced dose-dependent growth inhibition and apoptosis in HMC-1 and ROSA cells, regardless of the presence or absence of KIT D816V. In addition, JQ1 suppressed the proliferation of primary neoplastic MCs obtained from patients with ASM or MCL (IC50: 100-500 nm). In drug combination experiments, midostaurin (PKC412) and all-trans retinoic acid were found to cooperate with JQ1 in producing synergistic effects on survival in HMC-1 and ROSA cells. Taken together, we have identified BRD4 as a promising drug target in advanced SM. Whether JQ1 or other BET-bromodomain inhibitors are effective in vivo in patients with advanced SM remains to be elucidated.

The KIT D816V allele burden predicts survival in patients with mastocytosis and correlates with the WHO type of the disease.

KIT D816V is present in a majority of patients with systemic mastocytosis (SM). We determined the KIT D816V allele burden by quantitative real-time PCR in bone marrow and peripheral blood of 105 patients with mastocytosis. KIT D816V was detected in 92/105 patients (88%). Significant differences in the median allele burden were observed between disease subgroups: cutaneous mastocytosis (0.042%), indolent SM (0.285%), smoldering SM (5.991%), aggressive SM (9.346%), and SM with associated hematologic non-mast cell lineage disease (3.761%) (P < 0.001). The KIT D816V burden also correlated with serum tryptase (R = 0.5, P < 0.005) but not with mast cell infiltration in bone marrow or mediator symptoms. Moreover, the allele burden was of prognostic significance regarding survival (P < 0.01). Patients responding to cytoreductive therapy showed a significant decrease in KIT D816V (P < 0.05). To conclude, the KIT D816V burden correlates with the variant of mastocytosis, predicts survival, and is a valuable follow-up parameter in SM.

NI-1: a novel canine mastocytoma model for studying drug resistance and IgER-dependent mast cell activation.

BACKGROUND: Advanced mast cell (MC) disorders are characterized by uncontrolled growth of neoplastic MC in various organs, mediator-related symptoms, and a poor prognosis. Kit mutations supposedly contribute to abnormal growth and drug resistance in these patients. METHODS: We established a novel canine mastocytoma cell line, NI-1, from a patient suffering from MC leukemia. RESULTS: NI-1 cells were found to form mastocytoma lesions in NOD/SCID IL-2Rgamma(null) mice and to harbor several homozygous Kit mutations, including missense mutations at nucleotides 107(C→T) and 1187(A→G), a 12-bp duplication (nucleotide 1263), and a 12-bp deletion (nucleotide 1550). NI-1 cells expressed several MC differentiation antigens, including tryptase, Kit, and a functional IgE receptor. Compared to the C2 mastocytoma cell line harboring a Kit exon 11 mutation, NI-1 cells were found to be less responsive against the Kit tyrosine kinase inhibitors (TKI) masitinib and imatinib, but were even more sensitive against proliferation-inhibitory effects of the mammalian target of rapamycin (mTOR) blocker RAD001 and PI3-kinase/mTOR blocker NVP-BEZ235. The Kit-targeting multikinase inhibitors PKC412 and dasatinib were also found to override TKI resistance in NI-1 cells, and produced growth inhibition with reasonable IC(50) values (<0.1 µM). CONCLUSION: NI-1 may serve as a useful tool to investigate IgE-dependent reactions and mechanisms of abnormal growth and drug resistance in neoplastic MC in advanced mastocytosis.

Targeting of Hsp32 in solid tumors and leukemias: a novel approach to optimize anticancer therapy.

Heat shock protein 32 (Hsp32), also known as heme oxygenase-1 (HO-1), is a stress-related anti-apoptotic molecule, that has been implicated in enhanced survival of neoplastic cells and in drug-resistance. We here show that Hsp32 is expressed in most solid tumors and hematopoietic neoplasms and may be employed as a new therapeutic target as evidenced by experiments using specific siRNA and a Hsp32-targeting pharmacologic inhibitor. This Hsp-32 targeting drug, SMA-ZnPP, was found to inhibit the proliferation of neoplastic cells with IC(50) values ranging between 1 and 50 microM. In addition, SMA-ZnPP induced apoptosis in all neoplastic cells examined. Furthermore, SMA-ZnPP was found to synergize with other targeted and conventional drugs in producing growth-inhibition. Resulting synergistic effects were observed in all tumor and leukemia cells examined. Interestingly, several of the drug partners, when applied as single agents, induced the expression of Hsp32 in neoplastic cells, suggesting that synergistic effects resulted from SMA-ZnPP-induced ablation of a Hsp32-mediated survival-pathway that is otherwise used by tumor cells to escape drug-induced apoptosis. Together, Hsp32 is an important survival factor and target in solid tumors and hematopoietic neoplasms, and may be used to optimize anticancer therapy by combining conventional or targeted drugs with Hsp32-inhibitors. Based on these data, it seems desirable to explore the value of Hsp32-targeting drugs as anti-cancer agents in clinical trials.