In vitro evaluation of COM.TEC apheresis platelet concentrates using a preparation set and pathogen inactivation over a storage period of five days

Benzopyrone, a privileged scaffold in drug discovery: An overview of FDA-approved drugs and clinical candidates

Natural products have always served as an important source of drugs for treating various diseases. Among various privileged natural product scaffolds, the benzopyrone class of compounds has a substantial presence among biologically active compounds. One of the pioneering anticoagulant drugs, warfarin approved in 1954 bears a benzo-α-pyrone (coumarin) nucleus. The widely investigated psoriasis drugs, methoxsalen, and trioxsalen, also contain a benzo-α-pyrone nucleus. Benzo-γ-pyrone (chromone) containing drugs, cromoglic acid, and pranlukast were approved as treatments for asthma in 1982 and 2007, respectively. Numerous other small molecules with a benzopyrone core are under clinical investigation. The present review discusses the discovery, absorption, distribution, metabolism, excretion properties, and synthetic approaches for the Food and Drug Administration-approved and clinical-stage benzopyrone class of compounds. The role of the pyrone core in biological activity has also been discussed. The present review unravels the potential of benzopyrone core in medicinal chemistry and drug development.

Pathogen Reduction Technologies and Their Impact on Metabolic and Functional Properties of Treated Platelet Concentrates: A Systematic Review

Pathogen reduction technologies (PRTs) such as Mirasol and Intercept were developed to eliminate transfusion-transmitted infections. The impact of PRTs on platelet function during the storage period, their effect on platelet storage lesions, and the optimal storage duration following PRTs have not been clearly defined. The aim of this study was to systematically review the existing literature and investigate the impact of PRTs on functional alterations of PRT-treated platelets during the storage period. The authors identified 68 studies suitable to be included in this review. Despite the high heterogeneity in the literature, the results of the published studies indicate that PRTs may increase platelet metabolic activity, accelerate cell apoptosis, and enhance platelet activation, which can subsequently lead to a late exhaustion of activation potential and reduced aggregation response. However, these effects have a minor impact on platelet function during the early storage period and become more prominent beyond the fifth day of the storage period. Large in vivo trials are required to evaluate the effectiveness of PRT-treated platelets during the storage period and investigate whether their storage can be safely extended to more than 5 days, and up to the traditional 7-day storage period.

High platelet content can increase storage lesion rates following Intercept pathogen inactivation primarily in platelet concentrates prepared by apheresis

BACKGROUND

Pathogen inactivation methods for platelet concentrates are increasingly being used in blood banks worldwide. In vitro studies have demonstrated its effects on storage lesion, but little routine quality control data on blood banking outcomes have been reported.

MATERIALS AND METHODS

Swirling of distributed products was monitored before and after implementation of Intercept pathogen inactivation. Metabolic parameters pH, glucose and lactic acid were determined in a random cohort of expired pathogen-inactivated products. Storage lesion indicators in apheresis concentrates with premature low swirling were compared to concentrates with normal swirling.

RESULTS

During validation for implementing Intercept pathogen inactivation, pH and glucose levels decreased faster in apheresis platelet concentrates with high platelet content than with low platelet content or than in pathogen-inactivated pooled buffy coat-derived products. In routine products, glucose exhaustion was more often found in apheresis compared to buffy coat-derived platelet concentrates despite 3-7% more plasma carryover in the former. Annual incidence of premature low swirling increased significantly by 50% following implementation of pathogen inactivation implementation for apheresis but not for pooled buffy coat platelet concentrates. In addition, apheresis concentrates with premature low swirling had a significantly higher median platelet count (5·0 × 10¹¹ ) than unaffected products (3·5 × 10¹¹ ).

CONCLUSION

The risk of increased storage lesion rates following Intercept pathogen inactivation is higher for apheresis than for buffy coat-derived platelet concentrates, especially when platelet contents are higher than 5·0 × 10¹¹ .

Pathogen-reduced platelets for the prevention of bleeding

BACKGROUND

Platelet transfusions are used to prevent and treat bleeding in people who are thrombocytopenic. Despite improvements in donor screening and laboratory testing, a small risk of viral, bacterial, or protozoal contamination of platelets remains. There is also an ongoing risk from newly emerging blood transfusion-transmitted infections for which laboratory tests may not be available at the time of initial outbreak.One solution to reduce the risk of blood transfusion-transmitted infections from platelet transfusion is photochemical pathogen reduction, in which pathogens are either inactivated or significantly depleted in number, thereby reducing the chance of transmission. This process might offer additional benefits, including platelet shelf-life extension, and negate the requirement for gamma-irradiation of platelets. Although current pathogen-reduction technologies have been proven to reduce pathogen load in platelet concentrates, a number of published clinical studies have raised concerns about the effectiveness of pathogen-reduced platelets for post-transfusion platelet count recovery and the prevention of bleeding when compared with standard platelets.This is an update of a Cochrane review first published in 2013.

OBJECTIVES

To assess the effectiveness of pathogen-reduced platelets for the prevention of bleeding in people of any age requiring platelet transfusions.

SEARCH METHODS

We searched for randomised controlled trials (RCTs) in the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2016, Issue 9), MEDLINE (from 1946), Embase (from 1974), CINAHL (from 1937), the Transfusion Evidence Library (from 1950), and ongoing trial databases to 24 October 2016.

SELECTION CRITERIA

We included RCTs comparing the transfusion of pathogen-reduced platelets with standard platelets, or comparing different types of pathogen-reduced platelets.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane.

MAIN RESULTS

We identified five new trials in this update of the review. A total of 15 trials were eligible for inclusion in this review, 12 completed trials (2075 participants) and three ongoing trials. Ten of the 12 completed trials were included in the original review. We did not identify any RCTs comparing the transfusion of one type of pathogen-reduced platelets with another.Nine trials compared Intercept® pathogen-reduced platelets to standard platelets, two trials compared Mirasol® pathogen-reduced platelets to standard platelets; and one trial compared both pathogen-reduced platelets types to standard platelets. Three RCTs were randomised cross-over trials, and nine were parallel-group trials. Of the 2075 participants enrolled in the trials, 1981 participants received at least one platelet transfusion (1662 participants in Intercept® platelet trials and 319 in Mirasol® platelet trials).One trial included children requiring cardiac surgery (16 participants) or adults requiring a liver transplant (28 participants). All of the other participants were thrombocytopenic individuals who had a haematological or oncological diagnosis. Eight trials included only adults.Four of the included studies were at low risk of bias in every domain, while the remaining eight included studies had some threats to validity.Overall, the quality of the evidence was low to high across different outcomes according to GRADE methodology.We are very uncertain as to whether pathogen-reduced platelets increase the risk of any bleeding (World Health Organization (WHO) Grade 1 to 4) (5 trials, 1085 participants; fixed-effect risk ratio (RR) 1.09, 95% confidence interval (CI) 1.02 to 1.15; I2 = 59%, random-effect RR 1.14, 95% CI 0.93 to 1.38; I2 = 59%; low-quality evidence).There was no evidence of a difference between pathogen-reduced platelets and standard platelets in the incidence of clinically significant bleeding complications (WHO Grade 2 or higher) (5 trials, 1392 participants; RR 1.10, 95% CI 0.97 to 1.25; I2 = 0%; moderate-quality evidence), and there is probably no difference in the risk of developing severe bleeding (WHO Grade 3 or higher) (6 trials, 1495 participants; RR 1.24, 95% CI 0.76 to 2.02; I2 = 32%; moderate-quality evidence).There is probably no difference between pathogen-reduced platelets and standard platelets in the incidence of all-cause mortality at 4 to 12 weeks (6 trials, 1509 participants; RR 0.81, 95% CI 0.50 to 1.29; I2 = 26%; moderate-quality evidence).There is probably no difference between pathogen-reduced platelets and standard platelets in the incidence of serious adverse events (7 trials, 1340 participants; RR 1.09, 95% CI 0.88 to 1.35; I2 = 0%; moderate-quality evidence). However, no bacterial transfusion-transmitted infections occurred in the six trials that reported this outcome.Participants who received pathogen-reduced platelet transfusions had an increased risk of developing platelet refractoriness (7 trials, 1525 participants; RR 2.94, 95% CI 2.08 to 4.16; I2 = 0%; high-quality evidence), though the definition of platelet refractoriness differed between trials.Participants who received pathogen-reduced platelet transfusions required more platelet transfusions (6 trials, 1509 participants; mean difference (MD) 1.23, 95% CI 0.86 to 1.61; I2 = 27%; high-quality evidence), and there was probably a shorter time interval between transfusions (6 trials, 1489 participants; MD -0.42, 95% CI -0.53 to -0.32; I2 = 29%; moderate-quality evidence). Participants who received pathogen-reduced platelet transfusions had a lower 24-hour corrected-count increment (7 trials, 1681 participants; MD -3.02, 95% CI -3.57 to -2.48; I2 = 15%; high-quality evidence).None of the studies reported quality of life.We did not evaluate any economic outcomes.There was evidence of subgroup differences in multiple transfusion trials between the two pathogen-reduced platelet technologies assessed in this review (Intercept® and Mirasol®) for all-cause mortality and the interval between platelet transfusions (favouring Intercept®).

AUTHORS' CONCLUSIONS

Findings from this review were based on 12 trials, and of the 1981 participants who received a platelet transfusion only 44 did not have a haematological or oncological diagnosis.In people with haematological or oncological disorders who are thrombocytopenic due to their disease or its treatment, we found high-quality evidence that pathogen-reduced platelet transfusions increase the risk of platelet refractoriness and the platelet transfusion requirement. We found moderate-quality evidence that pathogen-reduced platelet transfusions do not affect all-cause mortality, the risk of clinically significant or severe bleeding, or the risk of a serious adverse event. There was insufficient evidence for people with other diagnoses.All three ongoing trials are in adults (planned recruitment 1375 participants) with a haematological or oncological diagnosis.

The clinical and biological impact of new pathogen inactivation technologies on platelet concentrates

Since 1990, several techniques have been developed to photochemically inactivate pathogens in platelet concentrates, potentially leading to safer transfusion therapy. The three most common methods are amotosalen/UVA (INTERCEPT Blood System), riboflavin/UVA-UVB (MIRASOL PRT), and UVC (Theraflex-UV). We review the biology of pathogen inactivation methods, present their efficacy in reducing pathogens, discuss their impact on the functional aspects of treated platelets, and review clinical studies showing the clinical efficiency of the pathogen inactivation methods and their possible toxicity.

Pathogen-reduced platelets for the prevention of bleeding

BACKGROUND

Platelet transfusions are used to prevent and treat bleeding in patients who are thrombocytopenic. Despite improvements in donor screening and laboratory testing, a small risk of viral, bacterial or protozoal contamination of platelets remains. There is also an ongoing risk from newly emerging blood transfusion-transmitted infections (TTIs) for which laboratory tests may not be available at the time of initial outbreak.One solution to reduce further the risk of TTIs from platelet transfusion is photochemical pathogen reduction, a process by which pathogens are either inactivated or significantly depleted in number, thereby reducing the chance of transmission. This process might offer additional benefits, including platelet shelf-life extension, and negate the requirement for gamma-irradiation of platelets. Although current pathogen-reduction technologies have been proven significantly to reduce pathogen load in platelet concentrates, a number of published clinical studies have raised concerns about the effectiveness of pathogen-reduced platelets for post-transfusion platelet recovery and the prevention of bleeding when compared with standard platelets.

OBJECTIVES

To assess the effectiveness of pathogen-reduced platelets for the prevention of bleeding in patients requiring platelet transfusions.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2013, Issue 1), MEDLINE (1950 to 18 February 2013), EMBASE (1980 to 18 February 2013), CINAHL (1982 to 18 February 2013) and the Transfusion Evidence Library (1980 to 18 February 2013). We also searched several international and ongoing trial databases and citation-tracked relevant reference lists. We requested information on possible unpublished trials from known investigators in the field.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing the transfusion of pathogen-reduced platelets with standard platelets. We did not identify any RCTs which compared the transfusion of one type of pathogen-reduced platelets with another.

DATA COLLECTION AND ANALYSIS

One author screened all references, excluding duplicates and those clearly irrelevant. Two authors then screened the remaining references, confirmed eligibility, extracted data and analysed trial quality independently. We requested and obtained a significant amount of missing data from trial authors. We performed meta-analyses where appropriate using the fixed-effect model for risk ratios (RR) or mean differences (MD), with 95% confidence intervals (95% CI), and used the I² statistic to explore heterogeneity, employing the random-effects model when I² was greater than 30%.

MAIN RESULTS

We included 10 trials comparing pathogen-reduced platelets with standard platelets. Nine trials assessed Intercept® pathogen-reduced platelets and one trial Mirasol® pathogen-reduced platelets. Two were randomised cross-over trials and the remaining eight were parallel-group RCTs. In total, 1422 participants were available for analysis across the 10 trials, of which 675 participants received Intercept® and 56 Mirasol® platelet transfusions. Four trials assessed the response to a single study platelet transfusion (all Intercept®) and six to multiple study transfusions (Intercept® (N = 5), Mirasol® (N = 1)) compared with standard platelets.We found the trials to be generally at low risk of bias but heterogeneous regarding the nature of the interventions (platelet preparation), protocols for platelet transfusion, definitions of outcomes, methods of outcome assessment and duration of follow-up.Our primary outcomes were mortality, 'any bleeding', 'clinically significant bleeding' and 'severe bleeding', and were grouped by duration of follow-up: short (up to 48 hours), medium (48 hours to seven days) or long (more than seven days). Meta-analysis of data from five trials of multiple platelet transfusions reporting 'any bleeding' over a long follow-up period found an increase in bleeding in those receiving pathogen-reduced platelets compared with standard platelets using the fixed-effect model (RR 1.09, 95% CI 1.02 to 1.15, I² = 59%); however, this meta-analysis showed no difference between treatment arms when using the random-effects model (RR 1.14, 95% CI 0.93 to 1.38).There was no evidence of a difference between treatment arms in the number of patients with 'clinically significant bleeding' (reported by four out of the same five trials) or 'severe bleeding' (reported by all five trials) (respectively, RR 1.06, 95% CI 0.93 to 1.21, I² = 2%; RR 1.27, 95% CI 0.76 to 2.12, I² = 51%). We also found no evidence of a difference between treatment arms for all-cause mortality, acute transfusion reactions, adverse events, serious adverse events and red cell transfusion requirements in the trials which reported on these outcomes. No bacterial transfusion-transmitted infections occurred in the six trials that reported this outcome.Although the definition of platelet refractoriness differed between trials, the relative risk of this event was 2.74 higher following pathogen-reduced platelet transfusion (RR 2.74, 95% CI 1.84 to 4.07, I² = 0%). Participants required 7% more platelet transfusions following pathogen-reduced platelet transfusion when compared with standard platelet transfusion (MD 0.07, 95% CI 0.03 to 0.11, I² = 21%), although the interval between platelet transfusions was only shown to be significantly shorter following multiple Intercept® pathogen-reduced platelet transfusion when compared with standard platelet transfusion (MD -0.51, 95% CI -0.66 to -0.37, I² = 0%). In trials of multiple pathogen-reduced platelets, our analyses showed the one- and 24-hour count and corrected count increments to be significantly inferior to standard platelets. However, one-hour increments were similar in trials of single platelet transfusions, although the 24-hour count and corrected count increments were again significantly lower.

AUTHORS' CONCLUSIONS

We found no evidence of a difference in mortality, 'clinically significant' or 'severe bleeding', transfusion reactions or adverse events between pathogen-reduced and standard platelets. For a range of laboratory outcomes the results indicated evidence of some benefits for standard platelets over pathogen-reduced platelets. These conclusions are based on data from 1422 patients included in 10 trials. Results from ongoing or new trials are required to determine if there are clinically important differences in bleeding risk between pathogen-reduced platelet transfusions and standard platelet transfusions. Given the variability in trial design, bleeding assessment and quality of outcome reporting, it is recommended that future trials apply standardised approaches to outcome assessment and follow-up, including safety reporting.

UVC Irradiation for Pathogen Reduction of Platelet Concentrates and Plasma

Besides the current efforts devoted to microbial risk reduction, pathogen inactivation technologies promise reduction of the residual risk of known and emerging infectious agents. A novel pathogen reduction process for platelets, the THERAFLEX UV-Platelets system, has been developed and is under clinical evaluation for its efficacy and safety. In addition, proof of principle has been shown for UVC treatment of plasma units. The pathogen reduction process is based on application of UVC light of a specific wavelength (254 nm) combined with intense agitation of the blood units to ensure a uniform treatment of all blood compartments. Due to the different absorption characteristics of nucleic acids and proteins, UVC irradiation mainly affects the nucleic acid of pathogens and leukocytes while proteins are largely preserved. UVC treatment significantly reduces the infectivity of platelet units contaminated by disease-causing viruses and bacteria. In addition, it inactivates residual white blood cells in the blood components while preserving platelet function and coagulation factors. Since no photoactive compound needs to be added to the blood units, photoreagent-related adverse events are excluded. Because of its simple and rapid procedure without the need to change the established blood component preparation procedures, UVC-based pathogen inactivation could easily be implemented in existing blood banking procedures.

In vitro evaluation of metabolic changes and residual platelet responsiveness in photochemical treated and gamma-irradiated single-donor platelet concentrates during long-term storage

BACKGROUND

Photochemical treatment (PCT) prevents replication of pathogens in platelet concentrates (PCs) by cross-linking nucleic acids and thus affects all cells containing DNA or RNA.

STUDY DESIGN AND METHODS

Fourteen double-dose single-donor PCs were divided into two study arms. The double-dose PCs were split in two identical units, PCT and conventional control PCs. Study Arm A consisted of seven PCT PCs with corresponding untreated controls, whereas Study Arm B consisted of seven PCT PCs with corresponding gamma-irradiated control. Metabolic changes and agonist-induced platelet (PLT) response were evaluated during storage for up to 12 days.

RESULTS

Higher rate of PLT destruction, illustrated by reduced PLT content, increased lactate dehydrogenase levels, and higher CD61+ microparticle formation rate, were observed after PCT. Generally PCT accelerated metabolic changes in PCs and reduced agonist-induced (collagen or thrombin receptor activator peptide [TRAP]) aggregation responses. Flow cytometric analysis of CD62P and CD42b (GPIbalpha) expression showed higher spontaneous PLT activation in PCT PCs from 5 days of storage. Correspondingly, a reduced capacity for up regulation of CD62P expression and down regulation of CD42b was observed in PCT PLTs after stimulation by the agonists ADP or TRAP.

CONCLUSION

Generally reduced in vitro PLT quality was observed after PCT during storage for up to 12 days, with marked reduction from 5 days of storage. Compared to conventional PCs, reduced agonist-induced aggregation and glycoprotein expression were observed after PCT during storage, corresponding to significantly higher level of spontaneous PLT activation in PCT PCs. Clinical studies of efficacy and safety of PCT PCs stored for more than 5 days are recommended.

In vitro evaluation of Haemonetics MCS+ apheresis platelet concentrates treated with photochemical pathogen inactivation following plasma volume reduction using the INTERCEPT Preparation Set

Pathogen inactivation using the INTERCEPT Blood System requires platelet resuspension in InterSol and reduced plasma. Platelets in plasma collected on the Haemonetics MCS+ were processed on the INTERCEPT Preparation Set for plasma volume reduction and addition of InterSol. The use of the Preparation Set resulted in a mean platelet loss of 5.6 +/- 3.4%. Subsequent photochemical treatment (PCT) with amotosalen and ultraviolet A light, and 7 days of storage, resulted in acceptable changes for platelet swirling, lactate, lactate dehydrogenase (LDH), platelet factor-4 (PF4), p-selectin, glycoprotein V (GpV), pO2, pCO2, tumour necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8). All platelet units processed with the Preparation Set and PCT met European requirements for leucoreduction and pH values.

Pathogen inactivation techniques

The desire to rid the blood supply of pathogens of all types has led to the development of many technologies aimed at the same goal--eradication of the pathogen(s) without harming the blood cells or generating toxic chemical agents. This is a very ambitious goal, and one that has yet to be achieved. One approach is to shun the 'one size fits all' concept and to target pathogen-reduction agents at the Individual component types. This permits the development of technologies that might be compatible with, for example, plasma products but that would be cytocidal and thus incompatible with platelet concentrates or red blood cell units. The technologies to be discussed include solvent detergent and methylene blue treatments--designed to inactivate plasma components and derivatives; psoralens (S-59--amotosalen) designed to pathogen-reduce units of platelets; and two products aimed at red blood cells, S-303 (a Frale--frangible anchor-linker effector compound) and Inactine (a binary ethyleneimine). A final pathogen-reduction material that might actually allow one material to inactivate all three blood components--riboflavin (vitamin B2)--is also under development. The sites of action of the amotosalen (S-59), the S-303 Frale, Inactine, and riboflavin are all localized in the nucleic acid part of the pathogen. Solvent detergent materials act by dissolving the plasma envelope, thus compromising the integrity of the pathogen membrane and rendering it non-infectious. By disrupting the pathogen's ability to replicate or survive, its infectivity is removed. The degree to which bacteria and viruses are affected by a particular pathogen-reducing technology relates to its Gram-positive or Gram-negative status, to the sporulation characteristics for bacteria, and the presence of lipid or protein envelopes for viruses. Concerns related to photoproducts and other breakdown products of these technologies remain, and the toxicology of pathogen-reduction treatments is a major ongoing area of investigation. Clearly, regulatory agencies have a major role to play in the evaluation of these new technologies. This chapter will cover the several types of pathogen-reduction systems, mechanisms of action, the inactivation efficacy for specific types of pathogens, toxicology of the various systems and the published research and clinical trial data supporting their potential usefulness. Due to the nature of the field, pathogen reduction is a work in progress and this review should be considered as a snapshot in time rather than a clear picture of what the future will bring.