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Background: Cryopreservation of platelets (PLTs) at -80°C with dimethyl sulfoxide (DMSO) can extend their shelf life up to 2 years. Cryopreserved PLTs (CRY-PLTs) are reported to have a greater in vivo hemostatic effect than liquid-stored PLTs. Aims of this study were: i. to evaluate the thrombin generation potential of buffy coat derived cryopreserved PLTs (CRY- BC PLT) in comparison with fresh buffy coat derived platelets concentrates; ii. to determine the efficacy and safety of CRY-PLTs transfusion in hematological patients with severe thrombocytopenia. Materials and methods: BC PLTs were obtained from 5 buffy coats and pooled. The final PLTs concentrates were leukoreduced by filtration and transferred to a 650 mL patented cryopreservation kit (Promedical ®) which allowed mixing with DMSO 25% in a closed system and following removal of supernatant without further manipulations. BC-PLTs were washed prior freezing, suspended in homologous plasma from 1 of the 5 donors to a final concentration of 200 mL and frozen at - 80°. CRY- BC PLTs were preserved at -80°C with 6% DMSO. A system of 3 accessory bags directly connected to the mother bag was adopted for the in vitro study, to avoid repeated freezing/thawing of samples. In vitro assays were performed before freezing and at 3,6 and 9 months after thawing. Before assay, CRY-BC PLT were thawed at 37°C and diluted in plasma to adjust to 300× 109/L PLTs. Fresh BC PLTs underwent the same dilution to adjust to 300 ×109/L PLTs. Thrombin generation (TGA) was tested in CRY BC-PLTs and compared to TG potential of fresh BC PLTs. TGA was triggered by the addition of 0.5 pmol/L of recombinant human tissue factor. Endogenous thrombin potential (ETP) and peak height (PH) were determined. Flow Cytometry assays for PLTs activation markers and thromboelastography were also determined on each sample. CRY-BC PLTs, separately prepared according to the above described method for in vivo study, were infused in five hematological patients with acute leukemia (AL) and severe thrombocytopenia (PLTs Results Fourty nine BC-PLTs from 245 healthy volunteer donors (145 males and 100 females, mean age: 48.16.±18.91) were prepared, cryopreserved and analyzed up to 9 months after storage. Cryopreserved PLTs show a good thrombin generation potential that is stably maintained up to 9 months after cryopreservation [ETP (nM min): 529.25±98.64 at T0, 558.82±114.67 at T3, at 548.57±93.38 T6 and 533.04±103.15 at T9 months, respectively; PH(nM): 132.77±44.9 at T0, 103.4±44.9 at T3, 108.0±36.7 at T6 and 132.0±44.6 at T9 months, respectively]. At TGA, fresh BC-PLTs (n=35) had a mean ETP of 760.13±130.11, PH was 138.9±40.2. Thrombin generation of CRY-BC PLTs is comparable to fresh BC-PLTs, even if slightly decreased. Infusion of CRY-BC PLT (1U) was effective in controlling mucosal bleeding (epistaxis) in two patients with AL and severe thrombocytopenia. CRY-PLT were also effective when administered for prophylaxis in 3 patients with very low platelets count secondary to chemotherapy. In vivo, thrombin generation is stably maintained up to 24 hours after infusion of 1 Unit of CRY-BC PLTs, without any adverse effect (mean ETP pre-treatment was: 414.13±160.60, 24 hours after transfusion: 326.95±152.54). CRY-BC PLTs were safe and they did not determine any thrombotic event. At flow-cytometry, CRY-BC PLTs expressed higher activation markers (CD62P,CD63) than fresh BC PLTs. CRY-BC PLTs are able to significantly decrease the time to clot formation and clot strength, as measured also by thromboelastography. CRY-BCPLTs activation/deterioration is accompanied by an effective hemostatic in vivo function. Conclusions: Cryopreserved PLTs have an enhanced hemostatic activity and a good thrombin generation potential. They are effective and safe in preventing and controlling bleeding, being available in emergency/urgency settings also for patients with acute leukemia and severe thrombocytopenia. Disclosures Reina: Promedical: Consultancy.

Purpose To evaluate the effect of whole pelvic radiotherapy (WPRT) in prostate cancer patients treated with RT and long-term (>1 year) androgen deprivation therapy (ADT). Methods and materials Prostate cancer patients with high-risk features (Stage T3-T4 and/or Gleason score ≥7 and/or prostate-specific antigen level ≥20 ng/mL) who had undergone RT and long-term ADT were included in the present analysis. Patients with bowel inflammatory disease, colon diverticula, and colon diverticulitis were excluded from WPRT and treated with prostate-only radiotherapy (PORT). Patients were grouped according to nodal risk involvement as assessed by the Roach formula using different cutoff levels (15%, 20%, 25%, and 30%). Biochemical disease-free survival (bDFS) was analyzed in each group according to the RT type (WPRT or PORT). Results A total of 358 patients treated between 1994 and 2007 were included in the analysis (46.9% with WPRT and 53.1% with PORT). The median duration of ADT was 24 months (range, 12–38). With a median follow-up of 52 months (range, 20–150), the overall 4-year bDFS rate was 90.5%. The 4-year bDFS rate was similar between the patients who had undergone WPRT or PORT (90.4% vs. 90.5%; p = NS). However, in the group of patients with the greatest nodal risk (>30%), a significant bDFS improvement was recorded for the patients who had undergone WPRT (p = .03). No differences were seen in acute toxicity among the patients treated with WPRT or PORT. The late gastrointestinal toxicity was similar in patients treated with PORT or WPRT (p = NS). Conclusions Our analysis has supported the use of WPRT in association with long-term ADT for patients with high-risk nodal involvement (>30%), although a definitive recommendation should be confirmed by a randomized trial.

A 2D array (PTW, type 10024), equipped with 729 vented plane parallel ion-chambers, has been calibrated as a detector for the in vivo comparison between measured and predicted portal doses for head-neck tumors. The comparison of absolute portal doses measured to ones predicted by a commercial treatment planning system within the field of view of the CT scanner, can help the delivered dose verification during different treatment fractions, in particular when the patient's present weight loss. This paper reports the preliminary results of the comparison of the portal doses measured by a PTW 2D array during several radiotherapy fractions and the predicted portal doses for seven patients undergoing head-neck tumor radiotherapy. The gamma index analysis supplied an agreement of more than 95% of the dose-point P(gamma)>95% within acceptance criteria, in terms of dose difference, DeltaD(max), and distance-agreement, Deltad(max), equal to 5% and 4mm, respectively. After the third week, one patient showed a decrease of P(gamma) values due to the markedly reduced patient's thickness. Even if the spatial resolution of the 2D array was 1cm, there were two advantages in the use of this 2D array as a portal dose device for IMRT quality control. The first one was the use of a stable and efficient absolute dosimeter for in vivo verification, although its construction and behavior for other gantry angles need to be tested, and the second one was the time efficiency in verifying the correct dose delivery in several fractions of the therapy. This study presents acceptance criteria for the comparison of TPS-predicted portal dose images with in vivo 2D ion-chamber measurements for IMRT. In particular, portal dose measurements offer clues for additional studies as to which indicators can signal the need for replanning during treatment.