Preclinical trial comparing radiotherapy alone versus standard radiochemotherapy in three human papilloma virus (HPV) negative and three HPV-positive head and neck squamous cell carcinoma (HNSCC) xenograft tumour models.

PURPOSE: To perform a preclinical trial comparing the efficacy of fractionated radiotherapy versus radiochemotherapy with cisplatin in HPV-positive and negative human head and neck squamous cell carcinoma (HNSCC) xenografts. MATERIAL AND METHODS: Three HPV-negative and three HPV-positive HNSCC xenografts in nude mice were randomized to radiotherapy (RT) alone or to radiochemotherapy (RCT) with weekly cisplatin. To evaluate tumour growth time, 20 Gy radiotherapy (±cisplatin) were administered in 10 fractions over 2 weeks. Dose-response curves for local tumour control were generated for RT with 30 fractions over 6 weeks to different dose levels given alone or combined with cisplatin (RCT). RESULTS: One of three investigated HPV-negative and two out of three HPV-positive tumour models showed a significant increase in local tumour control after RCT compared to RT alone. Pooled analysis of the HPV-positive tumour models showed a statistically significant and substantial benefit of RCT versus RT alone, with an enhancement ratio of 1.34. Although heterogeneity in response to both RT and RCT was also observed between the different HPV-positive HNSCC, these overall were more RT and RCT sensitive than HPV-negative models. CONCLUSION: The impact of adding chemotherapy to fractionated radiotherapy on local control was heterogenous, both in HPV-negative and in HPV-positive tumours, calling for predictive biomarkers. RCT substantially increased local tumour control in the pooled group of all HPV-positive tumours whereas this was not found in HPV-negative tumours. Omission of chemotherapy in HPV-positive HNSCC as part of a treatment de-escalation strategy is not supported by this preclinical trial.

Functional analysis of centrosomal kinase substrates in Drosophila melanogaster reveals a new function of the nuclear envelope component otefin in cell cycle progression.

Phosphorylation is one of the key mechanisms that regulate centrosome biogenesis, spindle assembly, and cell cycle progression. However, little is known about centrosome-specific phosphorylation sites and their functional relevance. Here, we identified phosphoproteins of intact Drosophila melanogaster centrosomes and found previously unknown phosphorylation sites in known and unexpected centrosomal components. We functionally characterized phosphoproteins and integrated them into regulatory signaling networks with the 3 important mitotic kinases, cdc2, polo, and aur, as well as the kinase CkIIß. Using a combinatorial RNA interference (RNAi) strategy, we demonstrated novel functions for P granule, nuclear envelope (NE), and nuclear proteins in centrosome duplication, maturation, and separation. Peptide microarrays confirmed phosphorylation of identified residues by centrosome-associated kinases. For a subset of phosphoproteins, we identified previously unknown centrosome and/or spindle localization via expression of tagged fusion proteins in Drosophila SL2 cells. Among those was otefin (Ote), an NE protein that we found to localize to centrosomes. Furthermore, we provide evidence that it is phosphorylated in vitro at threonine 63 (T63) through Aurora-A kinase. We propose that phosphorylation of this site plays a dual role in controlling mitotic exit when phosphorylated while dephosphorylation promotes G(2)/M transition in Drosophila SL2 cells.

Entacapone improves absorption of a coadministered salt in patients with Parkinson's disease.

Entacapone (EN) improves the efficacy of levodopa/dopadecarboxylase inhibitor (LD/DDI) formulations by inhibition of the enzyme catechol-O-methyltransferase (COMT). COMT inhibition also promotes the synthesis of basic LD metabolites, whereas DDI support the composition of acidic LD derivatives. LD metabolism correlates to the one of (13)C-sodium-octanoate, which is employed in breath tests to measure gastric emptying velocity. Objectives were to investigate the impact of COMT inhibition on the recovery rate of (13)C-sodium-octanoate in parkinsonian patients, who received first 100 mg LD/Carbidopa (CD) and the next day 100 mg LD/CD/EN combined with (13)C-sodium-octanoate in each case. The recovery rate of (13)C-sodium-octanoate was significant higher during the LD/CD/EN-compared with the LD/CD condition. COMT inhibition combined with LD/DDI improves absorption of a co-administered salt probably due to a COMT inhibition induced basic environment in gastrointestinal membranes. This improves dissolution and absorption of acids and salts. Thus it may enhance absorption of LD itself.

Entacapone improves complex movement performance in patients with Parkinson's disease.

BACKGROUND: A possible strategy to prolong plasma metabolism of Levodopa/Carbidopa (LD/CD) is Entacapone addition (EN), which improves impaired motor behaviour in patients with Parkinson's disease (PD). AIMS OF THE STUDY: Objectives were to evaluate the clinical response to an increased dopaminergic substitution with EN by clinical rating and assessment of complex motions and to investigate the change of movement in PD patients during repeat drug administration during an eight hour interval. METHODS: We used peg insertion with a computer based device and clinical rating for assessment of motor function in 20 treated PD patients. They received LD/CD and then the same LD/CD dosage plus EN in a standardised, open label fashion. RESULTS: Motor scores and performance of the instrumental task were significantly better and the fluctuation of movement was less intense during the LD/CD/EN condition according to the motor test outcomes. CONCLUSION: EN supplementation improves motor symptoms and provides a more continuous movement behaviour in PD patients.

Impact of gastric emptying on levodopa pharmacokinetics in Parkinson disease patients.

Adjunction of the catechol-O-methyltransferase (COMT) inhibitor entacapone (EN) to levodopa/carbidopa (LD/CD) improves motor symptoms in patients with Parkinson disease (PD) by a prolonged elimination of LD. But it is not known whether EN addition influences gastric emptying and thus LD pharmacokinetics and pharmacodynamics. Objectives were to simultaneously determine plasma LD elimination, gastric emptying, and clinical response after a single intake of the same LD dosage as LD/CD--or as (LD/CD/EN) formulation on 2 consecutive days. In both groups, PD patients with delayed gastric emptying had significant lower LD plasma concentrations. Addition of EN did not influence gastric emptying but significantly improved motor response, which was not different for patients with delayed gastric emptying. However, with and without EN adjunction gastric emptying distinctly contributes to the variability of plasma LD bioavailability. This may impact LD delivery to the brain and thus motor response in PD patients. Therefore, fine tuning of LD application, which considers gastric emptying, becomes more and more essential in advanced PD stages with a reduced striatal neuronal dopamine capacity, which is responsible for maintenance of motor response in early PD patients.

Inhibition of catechol-O-methyltransferase contributes to more stable levodopa plasma levels.

The short plasma half-life limits the antiparkinsonian efficacy of levodopa/carbidopa (LD/CD). Administration of LD/CD with the catechol-O-methyltransferase inhibitor entacapone in one tablet (LCE) may extend plasma half-life of LD and thus its effect on motor symptoms in patients with Parkinson's disease (PD). The objectives of this study were to monitor the motor response to a switch from LD/CD to LCE by a simultaneous performance of an instrumental motor test and rating of motor symptoms and to compare the LD plasma behavior between both conditions in terms of stability. Twenty-one treated PD patients received LD/CD and then the identical oral LD dosage of LCE within a standardized setting on 2 consecutive days. Rating better reflected the motor improvement after LD application than the instrumental test. Motor symptoms of PD patients decreased significantly more during the LCE than the LD/CD condition, probably due to significantly higher LD plasma levels and a significantly less pronounced fall of the LD concentrations following the second LD intake. Our study shows a more stable LD plasma behavior during LCE intake and accordingly a better effect on motor symptoms according to rating outcomes and motor test results to a lesser extent.