Relations entre p53, perturbations cytocinétiques, apoptose et survie cellulaire après agressions génotoxiques et en présence ou non de caféine

Les altérations du gène suppresseur de tumeur p53 constituent l'événement génétique le plus fréquemment observé dans les cancers humains. La protéine p53 possède en effet de multiples fonctions qui sont au centre de la plupart des concepts majeurs de la cancérologie fondamentale. Certains de ses rôles dans la réponse cellulaire aux agressions génotoxiques (bloc G1/S, bloc G2/M et déclenchement de l'apoptose) ont été largement mis en avant. On admet ainsi que les tumeurs malignes où p53 est inactivée sont plus résistantes aux agents anticancéreux en raison de leur impossibilité à s'engager dans la voie de l'apoptose. L'utilisation d'agents radio ou chimiosensibilisants comme la caféine pourrait également permettre d'augmenter l'efficacité des agents génotoxiques de manière différentielle pour les cellules où p53 est inactivée. Curieusement, il n'existe aucune démonstration formelle de ces hypothèses et l'importance que l'on doit attacher au phénotype p53 d'un cancer n'est toujours pas établie en ce qui concerne son traitement ou son pronostic.Tout d'abord les effets de la caféine sur la progression à travers le cycle cellulaire de fibroblastes humains normaux ont été réexaminés après irradiation UV ou ionisantes. L'analyse en parallèle de la prolifération cellulaire et des cinétiques de cycle cellulaire couplée à des expériences de stathmocinétique a permis de démontrer de manière formelle que contrairement au dogme établi la caféine ne permettait pas d'abroger le bloc G2/M. Nous avons ensuite utilisé plusieurs variants isogéniques isophénotypiques de la lignée cellulaire de carcinome thyroïdien K1, deux de ces lignées étaient déficientes en p53 par l'expression constitutive soit de la protéine virale E6 soit d'une protéine p53 mutée dominante négative alors que deux autres retenaient un phénotype p53 sauvage. Les résultats ont alors pu être étendus à une lignée tumorale humaine en montrant que la caféine ne permettait pas d'outrepasser le bloc G2/M radio-induit et ce indépendamment du statut fonctionnel de p53.Pour tenter d'élucider les relations pouvant exister entre l'apoptose et la survie cellulaire en fonction du phénotype p53 et en présence ou non de caféine, nous avons étudié l'action du cisplatine sur les différents variants de la lignée K1 en prenant en compte ces différents paramètres. Après exposition à des doses croissantes de cisplatine, la survie cellulaire a été mesurée par formation de colonies, et l'apoptose a été quantifiée manuellement par comptage des corps apoptotiques. Nous avons ainsi pu démontrer que dans ce modèle le degré d'apoptose observé et la survie cellulaire après exposition au cisplatine ne semblent pas liées, l'ampleur du phénomène apoptotique ne pouvant donc pas être retenue comme déterminant de la chimiosensibilité. Ainsi l'inhibition quasi-totale voire complète de l'apoptose lorsque p53 est inactivée n'a pas de signification univoque en terme de sensibilité au cisplatine que ce soit en présence ou non de caféine.En conclusion, ces travaux nous ont permis de remettre en question un dogme établi depuis plus de trente ans. La caféine ne permet pas d'outrepasser le bloc G2/M, ceci aussi bien dans un modèle de cellules humaines normales que dans un modèle de cellules tumorales après irradiation ionisantes ou UV et ce indépendamment du statut p53 fonctionnel ou non. Ces travaux illustrent la nécessité de la rigueur à garder dans toute expérience de cytocinétique où les perturbations du cycle cellulaire sont à mettre en parallèle avec la prolifération cellulaire, but ultime du cycle cellulaire, sous peine de mauvaises interprétations expérimentales. D'autres études seront nécessaires avant de pouvoir généraliser ces observations à tout type cellulaire. Nous confirmons également une fois encore l'absence de parallèle stricte entre phénomène apoptotique et radio ou chimiosenbilité.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Continuation of Bevacizumab vs Cetuximab Plus Chemotherapy After First Progression in KRAS Wild-Type Metastatic Colorectal Cancer

International audienceImportance:Second-line treatment with chemotherapy plus bevacizumab or cetuximab is a valid option for metastatic colorectal cancer.Objective:To evaluate the progression-free survival (PFS) rate at 4 months with chemotherapy plus bevacizumab vs cetuximab for patients with progression of metastatic colorectal cancer after bevacizumab plus chemotherapy.Design, Setting, and Participants:A prospective, open-label, multicenter, randomized phase 2 trial was conducted from December 14, 2010, to May 5, 2015. The main eligibility criterion was disease progression after bevacizumab plus fluorouracil with irinotecan or oxaliplatin in patients with wild-type KRAS exon 2 metastatic colorectal cancer. All analyses were performed on the modified intent-to-treat population.Interventions:Patients were randomized to arm A (FOLFIRI [fluorouracil and folinic acid combined with irinotecan] or modified FOLFOX6 [fluorouracil and folinic acid combined with oxaliplatin] plus bevacizumab) or arm B (FOLFIRI or modified FOLFOX6 plus cetuximab); the second-line chemotherapy regimen was chosen according to first-line treatment (crossover).Main Outcomes and Measures:The primary end point was the 4-month PFS rate. Secondary end points included safety, objective response rate, overall survival, and PFS.Results:A total of 132 patients (47 women and 85 men; median age, 63.0 years [range, 33.0-84.0 years]; 74 patients with an Eastern Cooperative Oncology Group performance status of 0, 54 patients with a performance status of 1, and 4 patients with unknown performance status) were included at 25 sites. The 4-month PFS rate was 80.3% (95% CI, 68.0%-88.3%) in arm A and 66.7% (95% CI, 53.6%-76.8%) in arm B. The median PFS was 7.1 months (95% CI, 5.7-8.2 months) in arm A and 5.6 months (95% CI, 4.2-6.5 months) in arm B (hazard ratio, 0.71; 95% CI, 0.50-1.02; P = .06), and the median overall survival was 15.8 months (95% CI, 9.5-22.3 months) in arm A and 10.4 months (95% CI, 7.0-16.2 months) in arm B (hazard ratio, 0.69; 95% CI, 0.46-1.04; P = .08). A central analysis of KRAS (exons 2, 3, and 4), NRAS (exons 2, 3, and 4), and BRAF (V600) was performed for 95 tumor samples. Eighty-one patients had wild-type KRAS and wild-type NRAS tumors.Conclusions and Relevance:The results of the PRODIGE18 (Partenariat de Recherche en Oncologie DIGEstive) study showed a nonsignificant difference but favored continuation of bevacizumab with chemotherapy crossover for patients with wild-type RAS metastatic colorectal cancer that progressed with first-line bevacizumab plus chemotherapy.Trial Registration:ClinicalTrials.gov identifier: NCT01442649 and clinicaltrialsregister.eu identifier: EUDRACT 2009-012942-22

Standard or accelerated methotrexate, vinblastine, doxorubicin and cisplatin as neoadjuvant chemotherapy for locally advanced urothelial bladder cancer: Does dose intensity matter?

International audienceBackground There is continuing controversy regarding the optimal regimen for neoadjuvant chemotherapy (NAC) in bladder cancer. Patients and methods We performed a retrospective analysis of 241 consecutive bladder cancer patients who received a combination of methotrexate, vinblastine, doxorubicin and cisplatin (MVAC) using a standard (52 patients) or an accelerated schedule (189 patients) as NAC before radical cystectomy in 17 centres of the French GEnito-urinary TUmour Group from March 2004–May 2013. Results The median age was 62 years. As expected, the median number of cycles, the median total dose of cisplatin and the median cisplatin dose intensity were higher in patients treated with the accelerated regimen. Conversely, the median duration of chemotherapy was shorter. Regarding toxicity, grade III/IV neutropenia, grade III thrombocytopenia and grade III anaemia as well were more frequently observed in patients treated with the standard regimen. Among 211 (88%) patients who proceeded to cystectomy, 75 (35%) patients achieved an ypT0 pN0 status (no pathologic residual tumour cells) with no significant difference according to the MVAC schedule. Three-year overall survival rates were 66.5% (95% confidence interval [CI], 56–79) and 72% (95% CI, 59.5–88) in the standard and accelerated cohorts, respectively. In the multivariate analysis, two independent prognostic parameters were retained: the ypT0 stage and the ypN0 stage. Heterogeneity test did not show any interaction with NAC regimens. Conclusion Similar pathological response and survival rates were observed whatever the chemotherapy regimen used. Haematological toxicity was greater in patients who received standard MVA

FFCD-1004 Clinical Trial: Impact of Cytidine Deaminase Activity on Clinical Outcome in Gemcitabine-Monotherapy Treated Patients.

Because cytidine deaminase (CDA) is the key enzyme in gemcitabine metabolism, numerous studies have attempted to investigate impact of CDA status (i.e. genotype or phenotype) on clinical outcome. To date, data are still controversial because none of these studies has fully investigated genotype-phenotype CDA status, pharmacokinetics and clinical outcome relationships in gemcitabine-treated patients. Besides, most patients were treated with gemcitabine associated with other drugs, thus adding a confounding factor. We performed a multicenter prospective clinical trial in gemcitabine-treated patients which aimed at investigating the link between CDA deficiency on the occurrence of severe toxicities and on pharmacokinetics, and studying CDA genotype-phenotype relationships.One hundred twenty patients with resected pancreatic adenocarcinoma eligible for adjuvant gemcitabine monotherapy were enrolled in this study promoted and managed by the Fédération Francophone de Cancérologie Digestive. Toxicities were graded according to National Cancer Institute's Common Terminology Criteria for Adverse Events Version 4. They were considered severe for grade ≥ 3, and early when occurring during the first eight weeks of treatment. CDA status was evaluated using a double approach: genotyping for 79A>C and functional testing. Therapeutic drug monitoring of gemcitabine and its metabolite were performed on the first course of gemcitabine.Five patients out of 120 (i.e., 4.6%) were found to be CDA deficient (i.e., CDA activity <1.3 U/mg), and only one among them experienced early severe hematological toxicity. There was no statistically significant difference in CDA activity between patients experiencing hematological severe toxicities (28.44%) and patients who tolerated the treatment (71.56%). CDA genetic analysis failed in evidencing an impact in terms of toxicities or in CDA activity. Regarding pharmacokinetics, a wide inter-individual variability has been observed in patients.This study, which included only 4.6% of CDA-deficient patients, failed in identifying CDA status as a predictive marker of toxicities with gemcitabine. A lack of statistical power because of smoothing effect of CDA variability as compared with real life conditions could explain this absence of impact.ClinicalTrials.gov NCT01416662

Multicentre randomised phase II trial of gemcitabine+platinum, with or without trastuzumab, in advanced or metastatic urothelial carcinoma overexpressing Her2

AIM: To investigate the efficacy and safety of gemcitabine and platinum salt, with or without trastuzumab, in patients with locally advanced or metastatic urothelial carcinoma overexpressing Her2. METHODS: The main eligibility criterion was Her2 overexpression on immunohistochemistry (IHC 2+ or 3+) of primary tumour tissue confirmed by fluorescence in situ hybridisation (FISH). Patients were randomised to Arm A: gemcitabine 1000mg/m(2) (days 1 and 8) plus either cisplatin (70mg/m(2)) or carboplatin (AUC=5) (day 1 every 3 weeks) or Arm B: added trastuzumab (8mg/kg loading dose, then 6 mg/kg every 21 days until progression). The primary end-point was progression-free survival (PFS). RESULTS: Among 563 screened patients, 75 (13.3%) were Her2 positive (IHC 2+/3+ and FISH+) and 61 met all eligibility criteria (median age, 64 years; 54/61 males; 50/61 baseline ECOG-PS 0-1; 11 locally advanced and 50 metastatic). There was no significant difference between Arms A and B in median PFS (10.2 versus 8.2 months, respectively, p=0.689), objective response rate (65.5% versus 53.2%, p=0.39), and median overall survival (15.7 versus 14.1 months, respectively, p=0.684). In an exploratory analysis, trastuzumab-treated patients receiving cisplatin rather than carboplatin-based chemotherapy fared better (PFS: 10.6 versus 8.0; OS: 33.1 versus 9.5 months). Myelosuppression was the main grade 3/4 toxicity. A case of grade 3 cardiotoxicity and one death from febrile neutropenia occurred in arm B. CONCLUSION: The unexpectedly low incidence of Her2 overexpression precluded the detection of a significant difference in efficacy on addition of trastuzumab to platinum-based chemotherapy with gemcitabine. However, the satisfactory tolerance of the combination warrants further studies, especially of the cisplatin-based combination, in well-defined patient subsets

Efficacy of lenalidomide in POEMS syndrome: a retrospective study of 20 patients.

International audiencePOEMS syndrome is a rare disorder characterized by polyneuropathy, monoclonal gammopathy, multiorgan involvement, and elevated vascular endothelial growth factor levels. Localized bone lesions require irradiation, whereas young patients with disseminated disease receive intensive treatment with stem cell support. Treatment of older and non responding patients is not yet standardized. We report the use of a combination of lenalidomide and dexamethasone in 20 patients with POEMS syndrome. Four patients were newly diagnosed, and 16 had relapsed or progressed after treatment. All but one of the patients responded: clinical improvements were noted in neuropathies (16/20) organomegaly (13/13), peripheral edema (14/15), and pulmonary hypertension (5/5). At least a very good partial response was noted in 68% of patients, with partial responses in 26%. Serum VEGF levels fell markedly in all 17 patients with available values. Twelve patients had 18-FDG-PET/CT at diagnosis (11 with positive findings), and nine patients during follow-up. The number of lesions fell markedly in five cases and remained stable in two cases, while two patients became negative. During a median follow-up of 22 months, four patients relapsed. Toxicity, predominantly hematological, was mild and manageable. Lenalidomide thus appears to be effective in POEMS syndrome, inducing high rate of clinical and biological responses