Evaluation of clinical studies of the efficacy of therapeutic apheresis

Extracorporeal photopheresis as a therapy for autoimmune diseases

Systemic autoimmune diseases (AID) have multiorgan, heterogeneous clinical presentations and are characterized by dysregulation of the immune system, immunodeficiency, irreversible organ damage and increased morbidity and mortality. Preventing or decreasing flares of AID correlate with durable disease control, significant reduction of inflammation and prevention of disability or therapy-related toxicity. There is an urgent need for better treatment of severe, therapy-refractory AID. Extracorporeal photopheresis (ECP) is a cell-based immunomodulatory treatment which has been extensively used in variety of autoimmune disorders for the last two decades. ECP treatment is FDA approved for the treatment of cutaneous T-cell lymphoma (CTCL) with particularly promising results seen in graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HCT). Prolonged therapy is safe, well tolerated and allows reduction of systemic immunosuppression in therapy-refractory patients. Both clinical and experimental evidence suggest that ECP mechanism of action is characterized by apoptosis and phagocytosis of activated cells by antigen-presenting cells (APC), secretion of anti-inflammatory cytokines and stimulation of regulatory T cells (Tregs). The focus of this paper is to review the current evidence of ECP use in the treatment of AID. Here, we summarize the experience of nine major AID from 65 published reports. The key findings demonstrate substantial evidence of ECP feasibility, safety and in some AID also promising efficacy. However, the role of ECP in AID therapy is not established as most published studies are retrospective with limited number of patients and the trials are small or poorly standardized. The available data support future investigations of ECP as a therapeutic modality for the treatment of AID in well-designed prospective clinical studies. J

The new approach to assignment of ASFA categories—Introduction to the fourth special issue: Clinical applications of therapeutic apheresis

The American Society for Apheresis (ASFA) Apheresis Applications Committee is responsible for a review and categorization of indications for therapeutic apheresis. The results of the review process were previously published in 1986, 1993, and 2000 as the ASFA Special Issues. The ASFA categories consist of categories I through IV, and category P (pending). This article describes the novel methodology, based on structured systematic review of the published literature, used to assign categories for indications for therapeutic apheresis. This is the first time each entity is presented as a fact sheet, which summarizes the evidence for the use of therapeutic apheresis. A detailed description of the fact sheet format and the individual fact sheets for categories I through III and category P are presented in the main article of this Special Issue. The diseases assigned to category IV are discussed in a separate article in this issue. Information on how the Apheresis Applications Committee proposes to include new diseases for category assignment is also provided.

Ensuring the comparability of comparison groups: is randomization enough?

BACKGROUND

It is widely believed that baseline imbalances in randomized trials must necessarily be random. In fact, there is a type of selection bias that can cause substantial, systematic and reproducible baseline imbalances of prognostic covariates even in properly randomized trials. It is possible, given complete data, to quantify both the susceptibility of a given trial to this type of selection bias and the extent to which selection bias appears to have caused either observable or unobservable baseline imbalances. Yet, in articles reporting on randomized trials, it is uncommon to find either these assessments or the information that would enable a reader to conduct them. Nevertheless, there have been a few published reports that contain descriptions of either this type of selection bias or indicators that it may have occurred.

OBJECTIVE

To document that the same type of selection bias has been described in numerous randomized trials and therefore that it represents a problem deserving of greater attention.

STUDY SELECTION

Computerized searches were not useful in locating trials with one or more elements that contribute to or are indicative of selection bias in randomized trials. We limit our treatment to trials that were previously questioned for susceptibility to selection bias or for large baseline imbalances.

RESULTS

We found 14 randomized trials that appear to be suspicious for selection bias. This may represent only the tip of the iceberg, because the status of other trials is inconclusive.

CONCLUSIONS

Authors of clinical trial reports should be required to disclose sufficient details to allow for an assessment of both allocation concealment and selection bias. The extent to which a randomized study was susceptible to selection bias should be considered in determining the relative contribution it makes to any subsequent meta-analysis, policy or decision.

Evidence-based Medicine for Apheresis: An Ongoing Challenge

Although much has been learned about the pathophysiologic process of thrombotic thrombocytopenic purpura (TTP) since Moschcowitz's initial description in 1924, its etiology and treatments remain problematic. We treated our first patient with TTP by plasma exchange in 1975 and have now treated over 160 patients. We report our experience exchanging patients using FFP, solvent detergent (SD) and cryopoor plasma as the exchange media. Most patients experience allergic reactions, some severe, during the course of treatment. However, use of SD plasma virtually eliminates all allergic reactions. Splenectomy was a much more common treatment prior to plasma exchange, but can still be a useful treatment option for some refractory patients. Recombinant ADAMTS-13 can hopefully provide not only more useful diagnostic assays but also could provide specific and more efficacious treatment of patients with both acquired and familial forms of TTP.