The SOLID Platelet Study

Background:

Platelets are cell fragments in the blood that help it clot. Some people get very low platelet counts during a disease or treatment. Low platelet counts can cause severe bleeding. Some people are not helped by platelet transfusions at the standard transfusion rate. This is called platelet transfusion refractoriness (PTR). Researchers want to learn more about transfusing platelets so they can make transfusions more effective.

Objectives:

To study the effects of transfusing platelets more slowly than the standard rate. To obtain data to improve the effectiveness of platelet transfusions in people with PTR and decrease the risk of bleeding in some people.

Eligibility:

Adults ages 18-100 who have very low platelet counts requiring platelet transfusion, and have evidence of PTR

Design:

Participants will be screened with a review their recent NIH medical records. They will have blood drawn.

Participants will have up to three 12-hour treatment blocks. They can have only one block per day. During each block, they will have 2 platelet transfusions in those 12 hours.

One transfusion will take place over 1 hour (SHORT infusion). The other will take place over 4 hours (LONG infusion).

Participants will be randomly put in 1 of 2 treatment groups. This will dictate whether they get the SHORT or LONG infusion first.

Participants will have blood drawn:

* When they enroll
* Right before each transfusion
* 2, 4, and 6 hours after each transfusion

Each blood draw will consist of a complete blood count. Smaller tubes that require only small amounts of blood will be used to minimize the amount of blood drawn.

...

Platelet transfusion can be a life-saving procedure in preventing or treating serious bleeding in patients who have low and/or dysfunctional platelets. Treatment of blood cancer and other blood diseases, as well as bone marrow transplantation, is not possible without platelet transfusion support. Unfortunately, 15- 25% of chronically transfused patients platelet counts will stop responding to these transfusions, putting them at risk for serious bleeding complications. The development of HLA antibodies is responsible for 4- 8% of this platelet transfusion refractoriness. The presence of HLA antibodies is a clinical complication that is generally managed by the selection of products that are negative for the antigens for which the patient has antibodies. Often, for patients with chronic and ongoing need, this selection is facilitated by targeted recruitment of donors with known HLA types (i.e., types that lack antigens cognate to the patient s known antibodies and are thus predicted to be compatible). However, for very broadly HLA- alloimmunized patients, compatible products may be exceedingly scarce or completely unavailable, precluding the ability to consistently provide products the patient will likely increment from. This research protocol is designed to evaluate the efficacy of a 4-HOUR continuous infusion of single donor, apheresis platelets in overcoming both alloimmune-mediated and non-alloimmune-mediated platelet refractoriness. We hypothesize that when we transfuse patients over a long duration, who have platelet refractoriness, the platelet counts will increase to higher numbers for an extended period of time in the peri-transfusion period when compared to shorter transfusion intervals.

Eligibility Criteria:
* INCLUSION CRITERIA:
* Ability to comprehend the investigational nature of the study and provide informed consent
* Thrombocytopenia

  * Causes of thrombocytopenia may be due to:

    1. Congenital causes
    2. Bone marrow
    3. Hematologic malignancies
    4. Treatment related
  * Thrombocytopenia is generally defined as one of the following:

    1. \<10K/uL without bleeding
    2. \<20K/uL for "complicated prophylaxis" in patient s determined to be at increased risk of bleeding or other complications
    3. \<50K/uL with evidence of active bleeding, such as intracranial hemorrhage, GI bleeding, pulmonary hemorrhage, uncontrolled epistaxis, hematuria.

       The treating provider may change the platelet transfusion threshold based on the clinical circumstance, patient population, and/or concurrent primary protocol considerations - similar to the PLADO study.
* Diagnosed with PTR, characterized by the following:

  * Lack of adequate post-transfusion platelet count increment, defined by, CCI \<5000/ul at 10-60 min after each of at least 2 consecutive platelet transfusions
  * Presence of anti-HLA class 1 type A and/or type B antibody, in the setting of PTR, as defined above, constitutes the HLA alloimmune-mediated subtype of PTR. Presence of one or more HPA antibodies in the setting of PTR, as defined above,constitutes the HPA alloimmune-mediated subtype of PTR. Failure to detect HLA or HPA antibodies will be categorized as non-alloimmune-mediated PTR. .

EXCLUSION CRITERIA:

* Less than 18-years-old
* Lack of ability to obtain informed consent
* Pregnant female
* Presence of ITP/autoimmune thrombocytopenia
* Immune platelet refractoriness responsive to treatment with IVIg or eculizumab, or other immunosuppressive therapy within the 3 preceding months. This is based on the wide variation in the duration therapeutic antibodies, with the upper limit frequently cited as 3 months.