Analysis of serum protein biomarkers, circulating tumor DNA, and dovitinib activity in patients with tyrosine kinase inhibitor-refractory gastrointestinal stromal tumors

BACKGROUND

An exploratory translational analysis was conducted as part of a phase II study of dovitinib to assess the relevance of soluble serum proteins and circulating tumor (ct) DNA (ctDNA) as biomarkers in patients with tyrosine kinase inhibitor (TKI)-refractory gastrointestinal stromal tumors (GISTs).

PATIENTS AND METHODS

Predose serum samples were collected from 30 patients on day 1 of cycle 1 and cycle 2. Serum levels of angiogenesis-related proteins were assessed by enzyme-linked immunosorbent assay, and Beads, emulsions, amplification, and magnetics (BEAMing) assays were carried out to detect mutations in serum ctDNA.

RESULTS

Dovitinib increased vascular endothelial growth factor (VEGF)165 (1.26-fold, P = 0.006), VEGF-A (1.27-fold, P = 0.004), placental growth factor (6.0-fold, P = 0.002), fibroblast growth factor 23 (1.45-fold, P = 0.02), and interleukin 8 (1.75-fold, P = 0.04) levels, and decreased soluble vascular endothelial growth factor receptor (sVEGFR)-2 levels (0.8-fold, P = 0.001). The changes in sVEGFR-2 were significantly associated with metabolic response determined by positron emission tomography (P = 0.02) and progression-free survival (PFS; P = 0.02). Secondary kinase mutations were identified in the ctDNA of 11 patients (41%), and these patients all had mutations involving KIT exon 17. Patients with secondary KIT mutations had significantly worse overall survival {median, 5.5 months [95% confidence interval (CI) 3.8-7.2 months]} than those with no detectable secondary mutations [9.8 months (95% CI 9.6-10.0 months); hazard ratio = 2.7 (95% CI 1.0-7.3); P = 0.047].

CONCLUSIONS

Changes in sVEGFR-2 levels were associated with dovitinib-mediated antitumor activity. Genotyping of serum ctDNA with BEAMing is useful for the identification of resistant mutations potentially associated with poor prognosis in patients with GISTs.

Influence of nutritional conditions on the mycelial growth and exopolysaccharide production in Paecilomyces sinclairii

AIMS

The objective of the study was to optimize the submerged culture conditions for the production of exopolysaccharide from Paecilomyces sinclairii.

METHODS AND RESULTS

The optimal temperature and initial pH for exopolysaccharide production by Paecilomyces sinclairii in shake flask culture were found to be 30 degrees C and 6.0, respectively. Sucrose (60 g l(-1)) and corn steep powder (10 g l(-1)) were the most suitable carbon and nitrogen source for exopolysaccharide production.

CONCLUSIONS

Under optimal culture medium, the maximum exopolysaccharide concentration in a 5-l stirred-tank fermenter indicated 7.4 g l(-1), which was approximately three times higher than that in basal medium. The maximum specific growth rates (micro max) and yield coefficient (Y(P/S)) in the optimal culture medium was 0.16 h(-1) and 0.19, respectively.

SIGNIFICANCE AND IMPACT OF THE STUDY

The optimal culture conditions reported in this article can be widely applied to the processes for submerged cultures of other mushrooms.