Prospective study assessing hypoxia-related proteins as markers for the outcome of treatment with sunitinib in advanced clear-cell renal cell carcinoma.

BACKGROUND: Previous studies suggest that expression of hypoxia markers may be associated with response to antiangiogenic drugs. Thus, we aimed to identify predictors of sunitinib outcome in clear-cell renal cell carcinoma (ccRCC). PATIENTS AND METHODS: The expression of eight key proteins related to hypoxia (CAIX, HIF1A, HIF2A, VEGFA, VEGFR1, VEGFR2, VEGFR3 and PDGFRB) and P-glycoprotein were assessed by immunohistochemistry in 67 primary ccRCC samples from prospectively recruited patients treated with first-line sunitinib. The proteins expression, VHL inactivation and EGLN3 mRNA content were compared with the patients' response to sunitinib. RESULTS: High expression of HIF2A and PDGFRB was associated with better sunitinib RECIST objective response (P = 0.024 and P = 0.026; respectively) and increased VEGFR3 expression was associated with longer progression-free survival (P = 0.012). VEGFR3 overexpression showed a negative correlation with VEGFR3 polymorphism rs307826 (P = 0.002), a sunitinib resistance predictor. With respect to overall survival (OS), high VEGFA was associated with short (P = 0.009) and HIF2A with long (P = 0.048) survival times. High EGLN3 mRNA content was associated with shorter OS (P = 0.023). CONCLUSIONS: We found an association between several proteins involved in hypoxia and sunitinib efficacy. In addition, low VEGFR3 expression was associated with worse outcome and with VEGFR3 rs307826 variant allele, reinforcing VEGFR3 as a marker of sunitinib resistance.

Polymorphisms in cytochromes P450 2C8 and 3A5 are associated with paclitaxel neurotoxicity.

Neurotoxicity is one of the most relevant dose-limiting toxicities of the anticancer drug paclitaxel. It exhibits substantial interindividual variability of unknown molecular basis, and represents one of the major challenges for the improvement of paclitaxel therapy. The extensive variability in paclitaxel clearance and metabolism lead us to investigate the association between polymorphisms in paclitaxel elimination pathway and neurotoxicity. We selected 13 relevant polymorphisms in genes encoding paclitaxel metabolizing enzymes (CYP2C8, CYP3A4 and CYP3A5) and transporters (organic anion transporting polypeptide (OATP) 1B1, OATP1B3 and P-glycoprotein) and genotyped them in 118 Spanish cancer patients treated with paclitaxel. After adjusting for age and treatment schedule, CYP2C8 Haplotype C and CYP3A5*3 were associated with protection (hazard ratio (HR) (per allele)=0.55; 95% confidence interval (CI)=0.34-0.89; P=0.014 and HR (per allele)=0.51; 95%CI=0.30-0.86; and P=0.012, respectively) and CYP2C8*3 with increased risk (HR (per allele)=1.72; 95%CI=1.05-2.82; and P=0.032). In each case, the allele causing increased paclitaxel metabolism was associated with increased neurotoxicity, suggesting an important role for metabolism and hydroxylated paclitaxel metabolites. We estimated the HR per paclitaxel-metabolism increasing allele carried across the three polymorphisms to be HR=1.64 (95% CI=1.26-2.14; P=0.0003). The results for P-glycoprotein were inconclusive, and no associations were observed for the other genes studied. The incorporation of this genetic data in treatment selection could help to reduce neurotoxicity events, thereby individualizing paclitaxel pharmacotherapy. These results warrant validation in independent series.

Rationalization of genetic testing in patients with apparently sporadic pheochromocytoma/paraganglioma.

Hereditary susceptibility to pheochromocytoma (PCC) and paraganglioma (PGL) represents a very complex genetic scenario. It has been reported that the absence of familial antecedents of the disease does not preclude the existence of a mutation affecting any of the five major susceptibility genes. In fact, 11-24% of apparently sporadic cases (without familial or syndromic antecedents) harbor an unexpected germline mutation, but we do not know what is happening in "truly apparently" sporadic patients (i.e., apparently sporadic cases diagnosed with only one tumor). In the present study, we have analyzed 135 apparently sporadic patients developing a single tumor for the five major susceptibility genes: VHL, RET, SDHB, SDHC, and SDHD. Fourteen percent of cases were found to harbor a germline mutation, and only 2.2% of patients were older than 45 years at onset. By taking into account the tumor location and a threshold age at onset of 45 years, we propose a rational scheme for genetic testing. Analyzing VHL and RET genes would be recommended only in young patients developing a single PCC. On the other hand, genetic testing of SDHD should be done in all patients developing an extra-adrenal tumor before the age of 45, and SDHC could be the responsible gene in cases developing a single head and neck tumor, independently of age. Finally, the analysis of SDHB should always be performed because of its association to malignancy and the low penetrance of mutations affecting this gene.

Molecular characterisation of a common SDHB deletion in paraganglioma patients.

BACKGROUND: Hereditary susceptibility to familial paraganglioma syndromes is mainly due to mutations in one of six genes, including three of the four genes encoding the subunits of the mitochondrial succinate dehydrogenase complex II. Although prevalence, penetrance and clinical characteristics of patients carrying point mutations affecting the genes encoding succinate dehydrogenase have been well studied, little is known regarding these clinical features in patients with gross deletions. Recently, we found two unrelated Spanish families carrying the previously reported SDHB exon 1 deletion, and suggested that this chromosomal region could be a hotspot deletion area. METHODS: We present the molecular characterisation of this apparently prevalent mutation in three new families, and discuss whether this recurrent mutation is due either to the presence of a founder effect or to a hotspot. RESULTS: The breakpoint analysis showed that all Iberian Peninsular families described harbour the same exon 1 deletion, and that a different breakpoint junction segregates in an affected French pedigree. CONCLUSIONS: After haplotyping the SDHB region, we concluded that the deletion detected in Iberian Peninsular people is probably due to a founder effect. Regarding the clinical characteristics of patients with this alteration, it seems that the presence of gross deletions rather than point mutations is more likely related to abdominal presentations and younger age at onset. Moreover, we found for the first time a patient with neuroblastoma and a germline SDHB deletion, but it seems that this paediatric neoplasia in a pheochromocytoma family is not a key component of this disease.