No abstract

LBA4506 Background: The course of pts with APC is often complicated by venous thromboembolic events (VTE). Anticoagulation therapy with LMWH may prevent VTE and is under discussion to improve overall survival (OS) in cancer. Based on our previous pilot study (Hilbig et al, Onkologie 2005;28(suppl 3)) indicating the safety and feasibility to the addition of the LMWH enoxaparin to chemotherapy in pts with APC we started the open, prospective, randomized, multicenter study to investigate the role of enoxaparin in these pts. Methods: Primary endpoint was the reduction of symptomatic VTE (sVTE) from an expected 10% to 3% within the first 12 weeks of treatment. The occurrence of sVTE (secured by an independent, blinded event review board) in 24 pts was calculated to be necessary in order to define the role of enoxaparin in decreasing the risk of VTE. Toxicity, time to progression (TTP), and OS were among the secondary endpoints of the study approved by the ethics committees of the participating centers. VTE-naive and chemotherapy-naive pts with histologically or cytologically confirmed APC were randomized to receive or not to receive additional LMWH (enoxaparin 1mg/kg once daily) starting in parallel to palliative systemic chemotherapy. Results: In January 2009 after recruitment of 312 pts the study was closed. There were 22 sVTE in 152 pts of the observation group (O) and 8 in 160 pts of the enoxaparin group (E). ITT and PP analyses demonstrated significant risk reductions from 14.5% to 5.0% (65% RRR) and 14.5% to 3.8% (74% RRR) for E, respectively. Major bleeding events were 9.9% for O and 6.3% for E (ITT; n.s.). In each group there was one tumor-related fatal hemorrhage. Preliminary data show no difference in TTP (O:19 vs. E:22 w) and OS (O:29 vs. E:31 w). Conclusions: Enoxaparin is effective and safe in the primary prevention of sVTE applied in parallel with cytotoxic chemotherapy in pts with APC. Final results on TTP and OS are pending. No significant financial relationships to disclose.

SummaryResistance to activated protein C is the most common hereditary cause for thrombosis and significantly linked to factor V Leiden. In this study, primers were designed to identify the factor V mutation by allele-specific PCR amplification. 126 patients with thromboembolic events were analysed using this technique, PCR-RFLP and direct sequencing. The concordance between these techniques was 100%. In 27 patients a heterozygous factor VGln506 mutation was detected, whereas one patient with recurrent thromboembolism was homozygous for the point mutation. Due to its time- and cost-saving features allele-specific amplification should be considered for screening of factor VGln506.

Immunostimulatory regimens are a game changer in the fight against cancer, but still only a minority of patients achieve clinical benefit. Combination with immunomodulatory drugs and agents converting otherwise non-immunogenic forms of cell death into bona fide “immunogenic cell death” (ICD) could improve the efficacy of these novel therapies. The aim of our study was to investigate conventional Amphotericin B (AmB) as an enhancer of antitumor immune responses. In tumor cell line models, AmB induced ICD with its typical hallmarks of calreticulin (CALR) expression and release of high mobility group box 1 (HMGB1) as well as Adenosine 5’-triphosphate (ATP). Interestingly, in contrast to non-ICD inducing treatments, ICD induction led to up-regulation of PD-L1-expression by ICD experiencing cells, resulting in decreased maturation of dendritic cells (DCs). Blocking this PD-L1 expression on tumor cells could unleash full ICD effects on antigen presenting cells. Even at sub-toxic concentrations, AmB was able to enhance CALR on leukemic blasts, particularly on phagocytic monoblastic THP-1 cells, which also showed features of “M1-like” differentiation after AmB exposure. The ability of AmB to increase the immunogenicity of tumor cells was confirmed in vivo in a mouse vaccination experiment. In conclusion, we demonstrate that AmB can promote antitumor immune responses in a dose-dependent manner by ICD induction, surface translocation of CALR on leukemic blasts even at sub-toxic concentrations, and “M1-like” polarization of phagocytic cells, making it noteworthy as potential booster for cancer immunotherapy. We additionally report for the first time that PD-L1 expression may be a feature of ICD, possibly as a negative feedback mechanism regulating the maturation status of DCs and thus indirectly affecting T-cell priming.