The impact of chemotherapy-induced side effects on medical care usage and cost in German hospital care--an observational analysis on non-small-cell lung cancer patients.

PURPOSE: To evaluate frequency and severity of adverse drug reactions (ADRs) and its economic consequences after standard dose (immuno-)chemotherapy (CT) of non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Subanalysis of a prospective, multicentre, longitudinal, observational cohort study; data were collected from patient interviews and pre-planned chart reviews. Costs were aggregated per CT line and presented from provider perspective. RESULTS: A total of 120 consecutive NSCLC patients (mean age, 63.0 ± 8.4 (SD) years; men, 64.2%; ECOG (Eastern Cooperative Oncology Group) performance status <2, 84.3%; tumour stage III/IV, 85%; history of comorbidity, 93.3%) receiving 130 CT lines were evaluated. 80% of CT lines were associated with grade 3 or 4 ADRs, 22.3% developed potential life-threatening complications, 77.7% were associated with at least one hospital stay (inpatient, 63.9%; outpatient/day clinic 39.2%, ICU 6.9%), with a mean cumulative number of 12.8 (±14.0 SD) hospital days. Mean (median) toxicity management costs per CT line (TMC-TL) amounted to €3,366 (€1,406) and were found to be higher for first-line compared to second-line treatment: €3,677 (€1,599) vs. €2,475 (€518). TMC-TL were particularly high in CT lines with ICU care €12,207 (€9,960). Eight out of 11 ICU stays were associated with grade 3 or 4 infections. Nine CT lines with ICU care accounted for 25% of total expenses (€109,861 out of €437,580). CONCLUSIONS: In first-line NSCLC treatment, in particular, CT toxicity management is expensive. Asymmetric cost distribution seems to be triggered by infection associated ICU care. Its avoidance should reduce patients' clinical burden and have considerable economic implications. Nevertheless, comparative observational studies have to confirm estimated savings.

Prospective multicentre randomized double-blind placebo-controlled parallel group study on the efficacy and tolerability of StroVac® in patients with recurrent symptomatic uncomplicated bacterial urinary tract infections.

PURPOSE: To evaluate efficacy and safety of vaccination with StroVac compared to placebo in patients with recurrent urinary tract infections (rUTI). MATERIAL AND METHODS: We performed a prospective, double-blinded, placebo-controlled study in patients with uncomplicated rUTI. Patients received three single intramuscular injections with StroVac every two weeks. Primary endpoint was the number of bacterial urinary tract infections (UTI) over 13.5 months after randomization and adjusted by the respective "baseline" value when comparing verum and placebo group. Secondary endpoints were the number of patients with non-recurrence, time to first recurrence, frequency of recurrences, and patients' self-assessment of quality of life using a validated questionnaire. RESULTS: 376 patients were randomized to both groups between January 2012 and March 2015. Mean age was 44.4 years. Patients were mainly female (98.4%). In the StroVac group (n = 188), the number of UTIs was reduced from 5.5 to 1.2, in the placebo group (n = 188) from 5.4 to 1.3 (p = 0.63). In patients with ≥ 7 UTIs prior to study inclusion, StroVac was statistically significantly superior to placebo (p = 0.048). However, in all other secondary endpoints, no statistical differences between the two groups could be seen (all p > 0.3). CONCLUSION: StroVac reduced the number of clinically relevant UTIs like in former studies but did not show statistically significant better results than the chosen placebo. Most likely, that was due to a, since confirmed, prophylactic effect of the chosen placebo itself. Therefore, placebo-controlled and double-blinded studies using a different ineffective placebo preparation are needed to determine the importance of StroVac in prophylaxis of rUTI.

Health resource consumption and costs attributable to chemotherapy-induced toxicity in German routine hospital care in lymphoproliferative disorder and NSCLC patients.

BACKGROUND: Multidrug chemotherapy (CT) is still associated with relevant side-effects. We assessed, under current practice patterns, frequency and severity of CT-induced toxicity and its economic consequences. PATIENTS AND METHODS: Prospective, multicentre, longitudinal, observational cohort study with lymphoproliferative disorder (LPD) and non-small-cell lung cancer (NSCLC) patients, receiving first- or second-line (immuno-) CT (excluding myeloablative CT). Data were collected from patient interviews and preplanned chart reviews. Costs in 2007 euros are presented from the provider perspective. RESULTS: Two hundred and seventy-three patients (n = 153 LPD; n = 120 NSCLC) undergoing a total of 1004 CT cycles were assessable (age ≥65 years, 40%; female, 36%; Eastern Cooperative Oncology Group performance status ≥2, 11%; tumour stage ≥III, 56%; history of comorbidity, 80%). Fifty percent of cycles were associated with grade 3/4 toxicity and 37% (n = 371) with at least one hospital stay (outpatient/day care n = 154; intensive care n = 19). Mean (median) toxicity-related costs amounted to €1032 (€86) per cycle. Costs rose exponentially with the number of grade 3/4 adverse drug reactions (ADRs) and were highest in cycles affected by more than four ADRs, €10 881 (€5455); in cycles with intensive care, €14 121 (€8833); and in cycles affected by grade 3/4 infections and febrile neutropenia/leukopenia, €7093 (€4531) and €5170 (€2899), respectively. Five percent of CT cycles accounted for 56% of total expenses. CONCLUSIONS: Individualised supportive care strategies are needed. Future research should focus on identifying toxicity clusters and patient characteristics predictive for high costs.

Extramedullary expansion of hematopoietic progenitor cells in interleukin (IL)-6-sIL-6R double transgenic mice.

Soluble cytokine receptors modulate the activity of their cognate ligands. Interleukin (IL)-6 in association with the soluble IL-6 receptor (sIL-6R) can activate cells expressing the gp130 signal transducer lacking the specific IL-6R. To investigate the function of the IL-6-sIL-6R complex in vivo and to discriminate the function of the IL-6-sIL-6R complex from the function of IL-6 alone, we have established a transgenic mouse model. Double-transgenic mice coexpressing IL-6 and sIL-6R were generated and compared with IL-6 and sIL-6R single-transgenic mice. The main phenotype found in IL-6-sIL-6R mice was a dramatic increase of extramedullary hematopoietic progenitor cells in liver and spleen but not in the bone marrow. In IL-6 single-transgenic mice and sIL-6R single-transgenic mice no such effects were observed. The high numbers of hematopoietic progenitor cells were reflected by a strong increase of peripheral blood cell numbers. Therefore, activators of the gp130 signal transducer like the IL-6-IL-6R complex may represent most powerful stimulators for extramedullary hematopoietic progenitor cells. gp130 activators may become important for the expansion of hematopoietic progenitor cells in vivo and in vitro.

Cetuximab plus oxaliplatin/leucovorin/5-fluorouracil in first-line metastatic gastric cancer: a phase II study of the Arbeitsgemeinschaft Internistische Onkologie (AIO).

BACKGROUND: Cetuximab enhances the efficacy of chemotherapy in several cancer types. This trial assessed the activity of cetuximab and chemotherapy in advanced gastric cancer. METHODS: Patients with previously untreated, metastatic, gastric cancer received cetuximab 400 mg m(-2) at first infusion followed by weekly infusions of 250 mg m(-2) combined with FUFOX (oxaliplatin 50 mg m(-2), 5-FU 2000 mg m(-2), and DL-folinic acid 200 mg m(-2) d1, 8, 15 and 22 qd36). The primary endpoint was tumour response. RESULTS: Overall, 52 patients were enrolled. The most common grade 3/4 toxicities were diarrhoea (33%), and skin toxicity (24%). Efficacy was evaluable in 46 patients who showed a response rate of 65% (CI 95%: 50-79%) including four complete responses. Time to progression (TTP) was 7.6 months (CI 95%: 5.0-10.1 months) and overall survival (OS) was 9.5 months (CI 95%: 7.9-11.1 months). Epidermal growth factor receptor (EGFR) was detectable in 60% of tumours but showed no correlation with treatment outcome. A KRAS mutation was found in only 1 of 32 (3%) tumour samples analysed. CONCLUSION: Cetuximab plus FUFOX showed an interesting high response rate in metastatic gastric cancer. Cetuximab plus platinum-fluoropyrimidine chemotherapy is at present being investigated in a phase III randomised controlled trial.

Cetuximab plus cisplatin-5-fluorouracil versus cisplatin-5-fluorouracil alone in first-line metastatic squamous cell carcinoma of the esophagus: a randomized phase II study of the Arbeitsgemeinschaft Internistische Onkologie.

BACKGROUND: This study assessed the activity of the mAb cetuximab in combination with cisplatin and 5-fluorouracil (5-FU) in advanced esophageal squamous cell carcinoma. PATIENTS AND METHODS: For a maximum of six 29-day cycles, patients received cisplatin 100 mg/m(2), day 1, plus 5-FU 1000 mg/m(2), days 1-5 (CF), either alone or in combination with cetuximab (CET-CF; 400 mg/m(2) initial dose followed by 250 mg/m(2) weekly thereafter). The primary end point was tumor response. Tumor material was obtained for analysis of KRAS mutation status. RESULTS: Sixty-two eligible patients were included, 32 receiving CET-CF and 30 CF. Cetuximab did not exacerbate grade 3/4 toxicity, except for rash (6% versus 0%) and diarrhea (16% versus 0%). The overall response rate according to RECIST criteria was 19% and 13% and the disease control rate 75% and 57% for the CET-CF and CF arms, respectively. With a median follow-up of 21.5 months, the median progression-free survival was 5.9 and 3.6 months and median overall survival 9.5 and 5.5 months for CET-CF and CF, respectively. No KRAS codon 12/13 tumor mutations were identified in 37 evaluated samples. CONCLUSION: Cetuximab can be safely combined with CF chemotherapy and may increase the efficacy of standard CF chemotherapy.

Weekly docetaxel monotherapy for advanced gastric or esophagogastric junction cancer. Results of a phase II study in elderly patients or patients with impaired performance status.

BACKGROUND: Three-weekly docetaxel is active in patients with advanced esophagogastric cancer but myelosuppression may make this schedule unsuitable for some patient groups such as elderly, pretreated, or poor performance status patients. PATIENTS AND METHODS: Eligible patients were chemonaive with Karnofsky index < or =70% and/or had received prior platinum-based chemotherapy. Docetaxel 35 mg/m(2) was administered on days 1, 8, 15, 22, 29, and 36 of a 49-day cycle. The primary endpoint was disease stabilization rate. RESULTS: Of 46 patients (median age, 68.5 years; 47% > or =70 years) included, 87% had Karnofsky index < or =70 and 50% had prior treatment. The safety profile was acceptable. Principal grade 3/4 toxicities were leukopenia (9%) and fatigue (14%). Fifteen patients experienced no progression for > or =100 days (disease stabilization rate: 36%). Overall response rate was 9%; median overall survival was 7.0 months. CONCLUSIONS: Weekly docetaxel was well tolerated and achieved disease stabilization in one-third of difficult-to-treat patients.

Neoadjuvant continuous infusion of weekly 5-fluorouracil and escalating doses of oxaliplatin plus concurrent radiation in locally advanced oesophageal squamous cell carcinoma: results of a phase I/II trial.

Oxaliplatin and 5-fluorouracil have a significant activity in locally advanced oesophageal squamous cell cancer (OSCC). However, their optimal dosage and efficacy when combined with concurrent radiotherapy as neoadjuvant treatment are unknown. This non-randomised, phase I/II study aimed to define the maximum tolerated dose (MTD) and assessed the histopathological tumour response rate to neoadjuvant oxaliplatin in weekly escalating doses (40, 45, 50 mg m(-2)) and continuous infusional 5-fluorouracil (CI-5FU; 225 mg m(-2)) plus concurrent radiotherapy. Patients had resectable OSCC. Resection was scheduled for 4-6 weeks after chemoradiotherapy. During phase I (dose escalation; n=19), weekly oxaliplatin 45 mg m(-2) plus CI-5FU 225 mg m(-2) was established as the MTD and was the recommended dosage for phase II. Oesophageal mucositis was the dose-limiting toxicity at higher doses. During phase II, histopathological responses (<10% residual tumour cells within the specimen) were observed in 10 of 16 patients (63%; 95% confidence interval: 39-82%). Overall, 16 of the 25 patients (64%) who underwent resection had a histopathological response; tumour-free resection (R0) was achieved in 80%. Neoadjuvant weekly oxaliplatin 45 mg m(-2) plus CI-5FU 225 mg m(-2) with concurrent radiotherapy provides promising histological response rates and R0 resection rates in locally advanced OSCC.

Randomized phase III study comparing irinotecan combined with 5-fluorouracil and folinic acid to cisplatin combined with 5-fluorouracil in chemotherapy naive patients with advanced adenocarcinoma of the stomach or esophagogastric junction.

BACKGROUND: We aimed to establish the superiority (or noninferiority if superiority was not achieved) in terms of time to progression (TTP) of irinotecan/5-fluorouracil (IF) over cisplatin/5-fluorouracil (CF) in chemonaive patients with adenocarcinoma of the stomach/esophagogastric junction. PATIENTS AND METHODS: Patients received either IF: i.v. irinotecan 80 mg/m(2) 30 min, folinic acid 500 mg/m(2) 2 h, 5-fluorouracil (5-FU) 2000 mg/m(2) 22 h, for 6/7 weeks or CF: cisplatin 100 mg/m(2) 1-3 h, with 5-FU 1000 mg/m(2)/day 24 h, days 1-5, every 4 weeks. RESULTS: In all, 333 patients were randomized and treated (IF 170, CF 163). Patient characteristics were balanced except more IF patients had Karnofsky performance status 100%. TTP for IF was 5.0 months [95% confidence interval (CI) 3.8-5.8] and 4.2 months (95% CI 3.7-5.5) for CF (P = 0.088). Overall survival (OS) was 9.0 versus 8.7 months, response rate 31.8% versus 25.8%, time to treatment failure (TTF) 4.0 versus 3.4 months for IF and CF, respectively. The difference in TTF was statistically significant (P = 0.018). IF was better in terms of toxic deaths (0.6% versus 3%), discontinuation for toxicity (10.0% versus 21.5%), severe neutropenia, thrombocytopenia and stomatitis, but not diarrhea. CONCLUSION: IF did not yield a significant TTP or OS superiority over CF, and the results of noninferiority of IF were borderline. However, IF may provide a viable, platinum-free front-line treatment alternative for metastatic gastric cancer.

Informatics and medicine--from molecules to populations.

OBJECTIVES: To clarify challenges and research topics for informatics in health and to describe new approaches for interdisciplinary collaboration and education. METHODS: Research challenges and possible solutions were elaborated by scientists of two universities using an interdisciplinary approach, in a series of meetings over several months. RESULTS AND CONCLUSION: In order to translate scientific results from bench to bedside and further into an evidence-based and efficient health system, intensive collaboration is needed between experts from medicine, biology, informatics, engineering, public health, as well as social and economic sciences. Research challenges can be attributed to four areas: bioinformatics and systems biology, biomedical engineering and informatics, health informatics and individual healthcare, and public health informatics. In order to bridge existing gaps between different disciplines and cultures, we suggest focusing on interdisciplinary education, taking an integrative approach and starting interdisciplinary practice at early stages of education.

Split-dose docetaxel, cisplatin and leucovorin/fluorouracil as first-line therapy in advanced gastric cancer and adenocarcinoma of the gastroesophageal junction: results of a phase II trial.

BACKGROUND: Phase II and III trials of docetaxel, cisplatin and fluorouracil (DCF) have shown superior efficacy versus cisplatin and fluorouracil alone but high rates of hematologic toxicity in advanced gastric cancer. To reduce toxicity while maintaining the efficacy of DCF, we investigated split doses of docetaxel (T), cisplatin (P), leucovorin (L) and fluorouracil (F). PATIENTS AND METHODS: Chemotherapy-naive patients with advanced gastric-/esophageal adenocarcinomas received T 50 mg/m(2) and P 50 mg/m(2) on days 1, 15 and 29 and L 500 mg/m(2) plus F 2000 mg/m(2) weekly, every 8 weeks. Because significant dose reductions to <80% became necessary in 80% of patients, the regimen was amended after the first 15 patients to T 40 mg/m(2), P 40 mg/m(2), L 200 mg/m(2) and F 2000 mg/m(2). The primary endpoint was response rate. RESULTS: Sixty patients were enrolled: 24 had locally advanced (LA) tumors and 36 had metastatic disease. Grade 3/4 toxicities included neutropenia (22%), febrile neutropenia (5%), diarrhea (20%) and lethargy (18%). The overall response rate was 47%. Twenty-three LA patients underwent secondary surgical resection (96%); complete resection was achieved in 87%. Overall, median time to progression and overall survival were 9.4 and 17.9 months, respectively (8.1 and 15.1 months, respectively, for patients with metastatic disease). CONCLUSION: T-PLF regimen is highly active and has a favorable toxicity profile.

Nucleophosmin-anaplastic lymphoma kinase of large-cell anaplastic lymphoma is a constitutively active tyrosine kinase that utilizes phospholipase C-gamma to mediate its mitogenicity.

Large-cell anaplastic lymphoma is a subtype of non-Hodgkin's lymphoma characterized by the expression of CD30. More than half of these lymphomas have a chromosomal translocation, t(2;5), that leads to the expression of a hybrid protein comprised of the nucleolar phosphoprotein nucleophosmin (NPM) and the anaplastic lymphoma kinase (ALK). Here we show that transfection of the constitutively active tyrosine kinase NPM-ALK into Ba/F3 and Rat-1 cells leads to a transformed phenotype. Oncogenic tyrosine kinases transform cells by activating the mitogenic signal transduction pathways, e.g., by binding and activating SH2-containing signaling molecules. We found that NPM-ALK binds most specifically to the SH2 domains of phospholipase C-gamma (PLC-gamma) in vitro. Furthermore, we showed complex formation of NPM-ALK and PLC-gamma in vivo by coimmunoprecipitation experiments in large-cell anaplastic lymphoma cells. This complex formation leads to the tyrosine phosphorylation and activation of PLC-gamma, which can be corroborated by enhanced production of inositol phosphates (IPs) in NPM-ALK-expressing cells. By phosphopeptide competition experiments, we were able to identify the tyrosine residue on NPM-ALK responsible for interaction with PLC-gamma as Y664. Using site-directed mutagenesis, we constructed a comprehensive panel of tyrosine-to-phenylalanine NPM-ALK mutants, including NPM-ALK(Y664F). NPM-ALK(Y664F), when transfected into Ba/F3 cells, no longer forms complexes with PLC-gamma or leads to PLC-gamma phosphorylation and activation, as confirmed by low IP levels in these cells. Most interestingly, Ba/F3 and Rat-1 cells expressing NPM-ALK(Y664F) also show a biological phenotype in that they are not stably transformed. Overexpression of PLC-gamma can partially rescue the proliferative response of Ba/F3 cells to the NPM-ALK(Y664F) mutant. Thus, PLC-gamma is an important downstream target of NPM-ALK that contributes to its mitogenic activity and is likely to be important in the molecular pathogenesis of large-cell anaplastic lymphomas.

Mechanisms of apoptosis-induction by rottlerin: therapeutic implications for B-CLL.

Constitutively activated signaling pathways contribute to the apoptosis-defect of B-CLL cells. Protein kinase C-delta is a permanently activated kinase and a putative downstream target of phosphatidylinositol-3 kinase in B-CLL. Blockade of protein kinase C-delta (PKC-delta) by the highly specific inhibitor rottlerin induces apoptosis in chronic lymphocytic leukaemia (CLL) cells. By co-culturing bone marrow stromal and CLL cells, we determined that the proapoptotic effect of rottlerin is not abolished in the presence of survival factors, indicating that a targeted therapy against PKC-delta might be a powerful approach for the treatment of CLL patients. The downstream events following rottlerin treatment engage mitochondrial and non-mitochondrial pathways and ultimately activate caspases that execute the apoptotic cell death. Herein we report that the inhibition of PKC-delta decreases the expression of the important antiapoptotic proteins Mcl-1 and XIAP accompanied by a loss of the mitochondrial membrane potential Deltapsi. In addition, we discovered that ZAP-70-expressing cells are significantly more susceptible to rottlerin-induced cell death than ZAP-70 negative cells. We finally observed that rottlerin can augment cell toxicity induced by standard chemotherapeutic drugs. Conclusively, PKC-delta is a promising new target in the combat against CLL.

The Bcr-Abl mutations T315I and Y253H do not confer a growth advantage in the absence of imatinib.

Mutations in the Bcr-Abl kinase domain are a frequent cause of imatinib resistance in patients with advanced CML or Ph+ ALL. The impact of these mutations on the overall oncogenic potential of Bcr-Abl and on the clinical course of the disease in the absence of imatinib is presently unclear. In this study, we analyzed the effects of the Bcr-Abl P-loop mutation Y253H and the highly imatinib resistant T315I mutation on kinase activity in vitro and transforming efficiency of Bcr-Abl in vitro and in vivo. Immunoprecipitated Bcr-AblY253H and Bcr-AblT315I proteins displayed similar kinase activities and substrate phosphorylation patterns as Bcr-Abl wildtype. We directly compared the proliferative capacity of mutant to wildtype Bcr-Abl in primary BM cells in vitro and in a murine transplantation model of CML by using a competitive repopulation assay. The results implicate that in the absence of imatinib, there is no growth advantage for cells carrying Bcr-AblT315I or Bcr-AblY253H compared to Bcr-Ablwt, whereas imatinib treatment clearly selects for leukemic cells expressing mutant Bcr-Abl both in vitro and in vivo. Thus, the analysed Bcr-Abl mutants confer imatinib resistance, but do not induce a growth advantage in the absence of imatinib.

I. A bioactive designer cytokine for human hematopoietic progenitor cell expansion.

Efficient expansion of hematopoietic progenitor cells requires, at least, the simultaneous stimulation of the receptors c-kit and gp130. While c-kit is activated by SCF; gp130, in cells which do not express sufficient amounts of IL-6R, can be activated by the complex of soluble IL-6R (sIL-6R) and IL-6. The therapeutic use of IL-6/sIL-6R, however, has been hampered by the high concentrations of the sIL-6R protein required. We have designed a fusion protein of sIL-6R and IL-6, linked by a flexible peptide chain, that was expressed to high levels. On gp130 expressing cells the fusion protein turned out to be fully active at 100 to 1,000-fold lower concentration than the combination of unlinked IL-6 and IL-6R. The fusion protein was used to effectively expand human hematopoietic progenitor cells ex vivo in a dose dependent fashion.

Visualisation of metastatic oesophageal and gastric cancer and prediction of clinical response to palliative chemotherapy using 18FDG PET.

AIM: This study assessed the value of (18)F-deoxyglucose positron emission tomography (FDG-PET) for visualisation and early metabolic response assessment in metastatic gastro-oesophageal cancer. PATIENTS, METHODS: Twenty-six patients who were treated for metastatic disease (20 adenocarcinomas, 6 squamous cell cancers) underwent FDG-PET before and two weeks after the onset of palliative chemotherapy with either oxaliplatin + 5-FU/LV or with docetaxel + capecitabine. PET results were validated according to clinical response based on RECIST criteria. RESULTS: Twenty-four tumours (92%) could be visualised by FDG-PET and were also assessable by a second PET scan at 2 weeks. The 2 tumours that were not detectable by PET were both gastric cancers belonging to the non-intestinal subtype according to Lauren. Median time to progression and overall survival were not significantly different for metabolic responders and non-responders (6.3 vs 5.3 months and 14.1 vs 12.5 months, respectively). CONCLUSION: In this heterogeneous study population, FDG-PET had a limited accuracy in predicting clinical response. However, the metabolic response prediction was particularly good in the subgroup of patients with oesophageal squamous cell cancer. Therefore, FDG-PET and assessment of cancer therapy clearly merits further investigation in circumscribed patient populations with metastatic disease.

Blockade of BCL-2 proteins efficiently induces apoptosis in progenitor cells of high-risk myelodysplastic syndromes patients.

Deregulated apoptosis is an identifying feature of myelodysplastic syndromes (MDS). Whereas apoptosis is increased in the bone marrow (BM) of low-risk MDS patients, progression to high-risk MDS correlates with an acquired resistance to apoptosis and an aberrant expression of BCL-2 proteins. To overcome the acquired apoptotic resistance in high-risk MDS, we investigated the induction of apoptosis by inhibition of pro-survival BCL-2 proteins using the BCL-2/-XL/-W inhibitor ABT-737 or the BCL-2-selective inhibitor ABT-199. We characterized a cohort of 124 primary human BM samples from MDS/secondary acute myeloid leukemia (sAML) patients and 57 healthy, age-matched controls. Inhibition of anti-apoptotic BCL-2 proteins was specifically toxic for BM cells from high-risk MDS and sAML patients, whereas low-risk MDS or healthy controls remained unaffected. Notably, ABT-737 or ABT-199 treatment was capable of targeting the MDS stem/progenitor compartment in high-risk MDS/sAML samples as shown by the reduction in CD34(+) cells and the decreased colony-forming capacity. Elevated expression of MCL-1 conveyed resistance against both compounds. Protection by stromal cells only partially inhibited induction of apoptosis. Collectively, our data show that the apoptotic resistance observed in high-risk MDS/sAML cells can be overcome by the ABT-737 or ABT-199 treatment and implies that BH3 mimetics might delay disease progression in higher-risk MDS or sAML patients.

Re-activation of mitochondrial apoptosis inhibits T-cell lymphoma survival and treatment resistance.

T lymphocyte non-Hodgkin's lymphoma (T-NHL) represents an aggressive and largely therapy-resistant subtype of lymphoid malignancies. As deregulated apoptosis is a frequent hallmark of lymphomagenesis, we analyzed gene expression profiles and protein levels of primary human T-NHL samples for various apoptotic regulators. We identified the apoptotic regulator MCL-1 as the only pro-survival BCL-2 family member to be highly expressed throughout all human T-NHL subtypes. Functional validation of pro-survival protein members of the BCL-2 family in two independent T-NHL mouse models identified that the partial loss of Mcl-1 significantly delayed T-NHL development in vivo. Moreover, the inducible reduction of MCL-1 protein levels in lymphoma-burdened mice severely impaired the continued survival of T-NHL cells, increased their susceptibility to chemotherapeutics and delayed lymphoma progression. Lymphoma viability remained unaffected by the genetic deletion or pharmacological inhibition of all alternative BCL-2 family members. Consistent with a therapeutic window for MCL-1 treatment within the context of the whole organism, we observed an only minimal toxicity after systemic heterozygous loss of Mcl-1 in vivo. We conclude that re-activation of mitochondrial apoptosis by blockade of MCL-1 represents a promising therapeutic strategy to treat T-cell lymphoma.