The SOLID Platelet Study

Short or Long Infusion Duration for Platelets: 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.

Study Overview

• Status: Terminated
• Conditions: Thrombocytopenia; Platelet Transfusion Refractoriness (PTR)
• Intervention / Treatment: Biological: Platelet Transfusion - LONG Platelet Transfusion; Biological: Platelet Transfusion - SHORT Platelet Transfusion

Detailed Description

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 human leukocyte antigen (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 patients 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.

• Study Type: Interventional
• Enrollment (Actual): 2
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • Maryland
    • Bethesda, Maryland, United States, 20892
      • National Institutes of Health Clinical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 100 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

• 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. Platelet count <10K/uL without bleeding
    2. Platelet count <20K/uL for "complicated prophylaxis" in patients determined to be at increased risk of bleeding or other complications

    3. Platelet count <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, Corrected Count Increment (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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Group A: LONG then SHORT transfusion; Subjects with thrombocytopenia (due to congenital causes, bone marrow failure, hematologic malignancies, and treatment-related) randomized to receive LONG platelet transfusion (Transfused over 4-HOURS via infusion pump or gravity) with follow up until 6 hours and then SHORT platelet transfusion (Transfused over 60-minutes via infusion pump or gravity) with follow up until 6 hours for a combined total of 12 hours. Subjects may receive up to two further subsequent blocks (one per day) to be administered to a subject in alternating order of SHORT and LONG platelet transfusions, for a maximum number of three blocks per subject.	Biological: Platelet Transfusion - LONG Platelet Transfusion; Platelets transfused over 4-HOURS; Biological: Platelet Transfusion - SHORT Platelet Transfusion; Platelets transfused over 60-minutes
Active Comparator: Group B: SHORT then LONG transfusion; Subjects with thrombocytopenia (due to congenital causes, bone marrow failure, hematologic malignancies, and treatment-related) randomized to receive SHORT platelet transfusion (Transfused over 60-minutes via infusion pump or gravity) with follow up until 6 hours and then LONG platelet transfusion (Transfused over 4-HOURS via infusion pump or gravity) with follow up until 6 hours for a combined total of 12 hours. Subjects may receive up to two further subsequent blocks (one per day) to be administered to a subject in alternating order of LONG and SHORT platelet transfusions, for a maximum number of three blocks per subject.	Biological: Platelet Transfusion - LONG Platelet Transfusion; Platelets transfused over 4-HOURS; Biological: Platelet Transfusion - SHORT Platelet Transfusion; Platelets transfused over 60-minutes

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Adjusted Platelet Increment Area Under the Curve (AUC)	The adjusted platelet increment area under the curve (AUC), obtained between 0-hours and 6-hours after start of the platelet transfusion. The AUC (i.e., AUC above the pretransfusion complete blood count (CBC) platelet count, minus the AUC below the pre-transfusion CBC's platelet count) determined by the 0-hour, 2-hour, 4-hour, and 6-hour CBC platelet concentrations, calculated using the trapezoid rule. Adjustment to the measured AUC done for the number of platelets transfused during the two transfusion periods (LONG and SHORT Transfusion durations) in one block.	0-6 hours post transfusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Participants With Bleeding During the Peri-transfusion Period	The efficacy of continuous platelet infusion on bleeding outcomes was assessed by number of participants with bleeding grade 1 or higher, measured during the peri-transfusion period by daily hemostatic assessments using the World Health Organization (WHO) bleeding scale. The WHO Bleeding Scale is a standardized tool used to assess and grade the severity of bleeding from 0-4: Grade 0: No bleeding. Grade 1: Petechiae (small, pinpoint hemorrhages). Grade 2: Mild blood loss. Grade 3: Gross blood loss (visible blood loss). Grade 4: Debilitating blood loss (severe blood loss that causes weakness)	One day before the first Transfusion Block until one day after the last Transfusion Block; up to 5 days total

Collaborators and Investigators

• Sponsor: National Institutes of Health Clinical Center (CC)
• Investigators: Principal Investigator: Willy A Flegel, M.D., National Institutes of Health Clinical Center (CC)

Publications and helpful links

Helpful Links

• NIH Clinical Center Detailed Web Page

Study record dates

Study Major Dates

• Study Start (Actual): June 10, 2019
• Primary Completion (Actual): July 31, 2021
• Study Completion (Actual): July 31, 2021

Study Registration Dates

• First Submitted: October 18, 2018
• First Submitted That Met QC Criteria: October 18, 2018
• First Posted (Actual): October 19, 2018

Study Record Updates

• Last Update Posted (Actual): May 9, 2025
• Last Update Submitted That Met QC Criteria: May 8, 2025
• Last Verified: February 1, 2025

More Information

Terms related to this study

• Keywords: Platelet Transfusion Refractoriness; Continuous Platelet Transfusion
• Additional Relevant MeSH Terms: Cytopenia; Hematologic Diseases; Blood Platelet Disorders; Thrombocytopenia
• Other Study ID Numbers: 190005; 19-CC-0005

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Data will be shared in de-identified format
• IPD Sharing Time Frame: After study completion
• IPD Sharing Access Criteria: Other researchers may access the data through Biomedical Translational Research Information System (BTRIS) database

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No