Preclinical safety of a nucleic acid-targeted Helinx compound: a clinical perspective

Evaluation of bacterial inactivation in random donor platelets and single-donor apheresis platelets by the INTERCEPT blood system

BACKGROUND:

Blood transfusion of contaminated components is a potential source of sepsis by a wide range of known and unknown pathogens. Collection mechanism and storage conditions of platelets make them vulnerable for bacterial contamination. Several interventions aim to reduce the transfusion of contaminated platelet units; however, data suggest that contaminated platelet transfusion remains very common.

AIM:

A pathogen inactivation system, “INTERCEPT”, to inactivate bacteria in deliberately contaminated platelet units was implemented and evaluated.

MATERIALS AND METHODS:

Five single-donor platelets (SDP) and five random donor platelets (RDP) were prepared after prior consent of donors. Both SDP and RDP units were deliberately contaminated by stable stock ATCC Staphylococcus aureus and Escherichia coli, respectively, with a known concentration of stock culture. Control samples were taken from the infected units and bacterial concentrations were quantified. The units were treated for pathogen inactivation with the INTERCEPT (Cerus Corporation, Concord, CA) Blood system for platelets (Amotosalen/UVA), as per the manufacturer's instructions for use. Post illumination, test samples were analyzed for any bacterial growth.

RESULTS:

Post-illumination test samples did not result in any bacterial growth. A complete reduction of >6 log₁₀S. aureus in SDP units and >6 log₁₀Escherichia coli in RDP units was achieved.

CONCLUSION:

The INTERCEPT system has been shown to be very effective in our study for bacterial inactivation. Implementation of INTERCEPT may be used as a mitigation against any potential bacterial contamination in platelet components.

[Feasibility study for Intercept platelets]

During 3 months, platelet concentrates prepared by "Établissement français du sang Pyrénées-Méditerranée" (Blood bank) were treated with the Intercept process (CERUS^©). This study primarily aimed to measure the organizational impact of this technology on transfusion chain. The introduction of Intercept did not raise any major difficulties, but required some adaptations upstream from the deployment. Prior information of health care institutions and physician was essential to anticipate the practical changes, including the prescription of platelet concentrates (CMV negative, irradiation). This study allowed to analyze also the transfusion consequences for patients, in the form of observational studies. The patients transfused with platelet concentrates treated with Intercept received more platelet concentrates (+12.9%), less rich in platelets (-12.8%), the cumulated quantity of platelet being stable.

Pathogen Inactivation of Platelet and Plasma Blood Components for Transfusion Using the INTERCEPT Blood System™

BACKGROUND: The transmission of pathogens via blood transfusion is still a major threat. Expert conferences established the need for a pro-active approach and concluded that the introduction of a pathogen inactivation/reduction technology requires a thorough safety profile, a comprehensive pre-clinical and clinical development and an ongoing hemovigilance program. MATERIAL AND METHODS: The INTERCEPT Blood System utilizes amotosalen and UVA light and enables for the treatment of platelets and plasma in the same device. Preclinical studies of pathogen inactivation and toxicology and a thorough program of clinical studies have been conducted and an active he-movigilance-program established. RESULTS: INTERCEPT shows robust efficacy of inactivation for viruses, bacteria (including spirochetes), protozoa and leukocytes as well as large safety margins. Furthermore, it integrates well into routine blood center operations. The clinical study program demonstrates the successful use for very diverse patient groups. The hemovigilance program shows safety and tolerability in routine use. Approximately 700,000 INTERCEPT-treated products have been transfused worldwide. The system is in clinical use since class III CE-mark registration in 2002. The safety and efficacy has been shown in routine use and during an epidemic. CONCLUSION: The INTERCEPT Blood System for platelets and plasma offers enhanced safety for the patient and protection against transfusion-transmitted infections.

Gastrointestinal bleeding in the cancer patient

Gastrointestinal bleeding is a common occurrence in patients with cancer and is a frequent indicator of a gastrointestinal malignancy. Rapid evaluation and treatment is key for the hemodynamically unstable patient. Endoscopy remains the cornerstone of diagnosis and management for cancer patients with gastrointestinal bleeding. The emergency physician should also be aware of other diagnostic and treatment modalities that may be needed to take care of these patients.

Assessment of safety in neonates for transfusion of platelets and plasma prepared with amotosalen photochemical pathogen inactivation treatment by a 1-month intravenous toxicity study in neonatal rats

BACKGROUND

It is estimated that approximately 300,000 neonates undergo transfusions annually. The neonatal immune system is immature, making such patients more susceptible to the effects associated with transfusion-transmitted bacteria, viruses, protozoa, and white blood cells (WBCs). The INTERCEPT Blood System is a photochemical process (PCT) utilizing amotosalen and long-wavelength ultraviolet to inactivate pathogens and WBCs in both platelet (PLT) and plasma components for transfusion. A series of clinical studies has shown PCT PLTs and PCT plasma to be safe and effective for transfusion in adults and pediatric patients. Because clinical studies in neonates are technically difficult and ethically challenging, preclinical toxicologic studies were conducted in neonatal rats to evaluate the safety of PCT blood components for neonates.

STUDY DESIGN AND METHODS

This study examined daily intravenous administration to neonatal rats of amotosalen in 35 percent:65 percent plasma:InterSol from 1 microg per kg per day (representing 1-unit transfusion) to 457 microg per kg per day (representing multiple transfusions) from Postnatal Day 4 (PND4) to PND31. Rats were observed for viability, clinical signs, and body weights until PND31 and then subjected to pathology evaluation. Hematology, clinical chemistry, and urinalysis data were also collected on PND31. Toxicokinetic parameters were evaluated on PND4 and PND31.

RESULTS

There were no amotosalen-related effects on clinical signs, body weight, hematology, clinical chemistry, urinalysis, gross pathology, or histopathology, despite the exposure of neonatal rats to amotosalen concentrations as high as approximately 48 times the standard exposure in adult patients.

CONCLUSION

This study demonstrates the safety of PCT for transfusion in neonatal rats and augments data from other studies and clinical use supporting the use of PCT in neonatal patients.

Proceedings of a Consensus Conference: pathogen inactivation-making decisions about new technologies

Significant progress has been made in reducing the risk of pathogen transmission to transfusion recipients. Nonetheless, there remains a continuing risk of transmission of viruses, bacteria, protozoa, and prions to recipients. These include many of the viruses for which specific screening tests exist as well as pathogens for which testing is currently not being done, including various species of bacteria, babesiosis, variant Creutzfeld-Jacob disease, hepatitis A virus, human herpes virus 8, chikungunya virus, Chagas disease, and malaria. Pathogen inactivation (PI) technologies potentially provide an additional way to protect the blood supply from emerging agents and also provide additional protection against both known and as-yet-unidentified agents. However, the impact of PI on product quality and recipient safety remains to be determined. The purpose of this consensus conference was to bring together international experts in an effort to consider the following issues with respect to PI: implementation criteria; licensing requirements; blood service and clinical issues; risk management issues; cost-benefit impact; and research requirements. These proceedings are provided to make available to the transfusion medicine community the considerable amount of important information presented at this consensus conference.

Pathogen inactivation: a new paradigm for preventing transfusion-transmitted infections

Remarkable improvements have been made in blood safety since the onset of the HIV epidemic. However, the current paradigm does not prevent all transfusion-transmitted infections and is reactive to new agents, thus accepting that some patients may be harmed before preventive measures are introduced. Several methods are now available that selectively damage DNA and RNA, thus inactivating pathogens contaminating blood components while not damaging the cells or plasma proteins of the blood component. Clinical trials have been completed and pathogen-inactivated platelets and plasma are widely used in Europe. A recent consensus conference recommended implementation of pathogen inactivation when a feasible and safe method is available that inactivates a broad spectrum of pathogens. The shortcomings of our present paradigm for preventing transfusion-transmitted diseases are described, along with a summary of the status of pathogen inactivation.

Coagulation function in fresh-frozen plasma prepared with two photochemical treatment methods: methylene blue and amotosalen

BACKGROUND

Pathogen inactivation of plasma intended for transfusion is now the standard of care in Belgium. Two methods for treatment of single plasma units are available: amotosalen plus ultraviolet A light and methylene blue plus visible light. This study compared the quality and stability of plasma treated with these two methods.

STUDY DESIGN AND METHODS

Plasma units made from a pool of two ABO-matched fresh apheresis units were photochemically treated with either amotosalen (PCT-FFP) or methylene blue (MB-FFP). A total of 12 paired samples were evaluated. Plasma coagulation function was assessed at three time points: immediately after treatment, after 30 days of frozen storage, and an additional 24 hours at 4 degrees C after thawing. Comparison between PCT-FFP and MB-FFP was assessed with the paired t test and a p value of less than 0.05 indicated statistical significance.

RESULTS

Based on statistical analysis, mean levels of factor (F)II, FXII, FXIII, von Willebrand antigen, ADAMTS-13, D-dimers, and protein C were equivalent between PCT-FFP and MB-FFP for all three time points. PCT-FFP exhibited shorter mean prothrombin time, activated partial thromboplastin time (two time points), and thrombin time and higher mean levels of fibrinogen, FXI, and protein S than MB-FFP. Retention of FV, FVII, FVIII, FX, or von Willebrand factor:ristocetin cofactor in PCT-FFP was either equivalent to or higher than MB-FFP. MB-FFP contained higher mean levels of plasminogen, antithrombin, and plasmin inhibitor than PCT-FFP. Retention of F IX in MB-FFP was higher than PCT-FFP only after the 4 degrees C storage after thawing.

CONCLUSION

There is adequate preservation of therapeutic coagulation factor activities in both PCT-FFP and MB-FFP. The overall coagulation factor levels and stability of PCT-FFP were better preserved than MB-FFP.

Platelets photochemically treated with amotosalen HCl and ultraviolet A light correct prolonged bleeding times in patients with thrombocytopenia

BACKGROUND

Photochemical treatment (PCT) with amotosalen HCl with ultraviolet A illumination inactivates pathogens and white blood cells in platelet (PLT) concentrates.

STUDY DESIGN AND METHODS

In a Phase II crossover study, 32 patients with thrombocytopenia received one transfusion of PCT and/or one transfusion of untreated (reference) apheresis PLTs. Hemostatic efficacy was assessed with the cutaneous template bleeding time and clinical observations.

RESULTS

Paired bleeding time data for PCT and reference transfusions were available for 10 patients. Mean pretransfusion bleeding times were 29.2 +/- 1.6 minutes in the PCT group and 28.7 +/- 2.5 minutes in the reference group. After transfusion of a dose of PLTs of at least 6.0 x 10(11), mean 1-hour posttransfusion template bleeding times corrected to 19.3 +/- 9.5 minutes in the PCT group and 14.3 +/- 6.5 minutes in the reference group (p = 0.25). In 29 patients receiving paired PCT and reference transfusions, mean 1-hour posttransfusion PLT count increments were 41.9 x 10(9) +/- 20.8 x 10(9) and 52.3 x 10(9) +/- 18.3 x 10(9) per L for PCT and reference, respectively (p = 0.007), and mean 1-hour posttransfusion PLT corrected count increments (CCIs) were 10.4 x 10(3) +/- 4.9 x 10(3) and 13.6 x 10(3) +/- 4.3 x 10(3) for PCT and reference, respectively (p < 0.001). The time to next PLT transfusion was 2.9 +/- 1.2 days after PCT transfusions versus 3.4 +/- 1.3 days after reference transfusions (p = 0.18). Clinical hemostasis was not significantly different after PCT and reference transfusions.

CONCLUSION

PCT PLTs provided correction of prolonged bleeding times and transfusion intervals not significantly different than reference PLTs despite significantly lower PLT count increments and CCIs.

The Role of Photochemical Treatment With Amotosalen and UV-A Light in the Prevention of Transfusion-Transmitted Cytomegalovirus Infections

Primary cytomegalovirus (CMV) infection is usually asymptomatic in immunocompetent patients but can cause serious life-threatening complications in immunocompromised CMV-seronegative patients, including patients receiving a bone marrow or peripheral blood stem cell transplant, recipients of some solid-organ transplants, and low-birth-weight neonates. Current recommendations for preventing transfusion-transmitted CMV (TT-CMV) infection in these patients include exclusive use of CMV-seronegative and/or leukoreduced cellular blood components (red blood cells and platelets) for transfusion. However, breakthrough cases of TT-CMV still occur. Despite improving the safety of blood components, testing remains a reactive approach to blood safety. In contrast, pathogen inactivation technologies offer a proactive approach with the potential to further improve blood safety. To reduce the risks associated with platelet transfusions, a photochemical treatment (PCT) process using a combination of the psoralen amotosalen HCl and long-wavelength UV light has been developed and introduced into clinical practice in Europe. PCT has been shown to result in greater than 5.9-log reductions in infectivity of human CMV in platelet concentrates and to prevent the transfusion transmission of murine CMV in a mouse transfusion model. Thus, PCT pathogen inactivation may play a role in further reducing the incidence of TT-CMV infection in patients who are at risk for serious CMV disease. Because PCT is a technology that targets nucleic acids, it also offers a proactive process for the inactivation of a broad range of viral, bacterial, and protozoan pathogens in addition to CMV.

Fresh frozen plasma prepared with amotosalen HCl (S-59) photochemical pathogen inactivation: transfusion of patients with congenital coagulation factor deficiencies

BACKGROUND

Photochemical treatment (PCT) with amotosalen HCl (S-59) was developed to inactivate pathogens and white blood cells in plasma (PCT-FFP) used for transfusion support.

STUDY DESIGN AND METHODS

An open-label, multicenter trial was conducted in patients with congenital coagulation factor deficiencies (factors [F]I, FII, FV, FVII, FX, FXI, and FXIII and protein C) to measure the kinetics of specific coagulation factors, hemostatic efficacy, and safety of PCT-FFP. Posttransfusion prothrombin time (PT), partial thromboplastin time (PTT), and clinical hemostasis were evaluated before and after PCT-FFP transfusions.

RESULTS

Thirty-four patients received 107 transfusions of PCT-FFP for kinetic studies or therapeutic indications (mean dose, 12.8 +/- 8.5 mL/kg). Incremental factor recoveries ranged from 0.9 to 2.4 IU per dL per IU per kg (FII, FV, FVII, FX, FXI, and protein C). Mean pretransfusion PT (20.7 +/- 22.2 sec) corrected after PCT-FFP (13.8 +/- 2.4 sec, p < 0.001). Mean pretransfusion PTT (51.2 +/- 29.3 sec) corrected after PCT-FFP (32.0 +/- 5.1 sec, p < 0.001). Thirteen patients required 77 transfusions for therapeutic indications. PCT-FFP provided effective hemostasis and was well tolerated.

CONCLUSIONS

Replacement coagulation factors in PCT-FFP exhibited kinetics and therapeutic efficacy consistent with conventional FFP.

Protecting the blood supply from emerging pathogens: the role of pathogen inactivation

Although the risk of infection by blood transfusion is relatively low, breakthrough infections still occur, Transfusion-related fatalities caused by infections continue to be reported, and blood is not tested for many potentially dangerous pathogens. The current paradigm for increasing the safety of the blood supply is the development and implementation of laboratory screening methods and restrictive donor criteria. When considering the large number of known pathogens and the fact that pathogens continue to emerge, it is clear that the utility of new tests and donor restrictions will continue to be a challenge when considering the cost of developing and implementing new screening assays, the loss of potential donors, and the risk of testing errors. Despite improving the safety of blood components, testing remains a reactive approach to blood safety. The contaminating organisms must be identified before sensitive tests can be developed. In contrast, pathogen inactivation is a proactive strategy designed to inactivate a pathogen before it enters the blood supply. Almost all pathogen inactivation technologies target nucleic acids, allowing for the inactivation of a variety of nucleic acid-containing pathogens within plasma, platelets, or red blood cells thus providing the potential to reduce transfusion-transmitted diseases. However, widespread use of a pathogen inactivation technology can only be realized when proven safe and efficacious and not cost-prohibitive.

Progress toward a pathogen-free blood supply

Although the nation's blood supply is safer than ever, a small risk of transfusion-transmitted infection remains. Present strategies to further reduce the risk, such as the donor medical evaluation or laboratory testing, will not likely eliminate this risk. A different approach involves treating donated blood to eliminate its infectivity. A pathogen-inactivated plasma product was available for several years but was recently withdrawn. Several other methods are under development, but all of these prevent nucleic acids from replicating, thus inactivating any contaminating viruses or bacteria. Toxicity, mutagenicity, and safety margins seem to be adequate, and damage to blood proteins or cellular elements is minimal. Clinical trials of pathogen-inactivated platelets have been completed in Europe and in the United States, and phase III clinical trials of pathogen-inactivated red blood cells are underway in the United States. If these encouraging results are sustained, the risk of transfusion-transmitted disease may be nearly eliminated.

Safety of the blood supply: role of pathogen reduction

Even though the blood supply is very safe, the risk of transfusion transmitted disease is not zero. To improve the safety of the blood supply, pathogen reduction (PR) technology has been developed. The principle of most current PR strategies involves modifying DNA or RNA templates and making them inaccessible to DNA or RNA polymerase. Several platforms of pathogen reduction are available including psoralens, alkylating compounds, binary ethyleneimine-like compounds, riboflavin, methylene blue, and solvent-detergent treatment. PR systems have been designed for RBC, plasma, and platelets. PR technology has been found to be effective for a variety of pathogens including lipid-enveloped and non-enveloped viruses, bacteria and parasites. Pre-clinical studies and Phase III clinical trials to evaluate the efficacy and safety of these PR technologies are currently ongoing.