Ammar AlsughayirAmmar Alsughayir

TM FellowTM Fellow

OttawaOttawa

BackgroundBackground

Platelet supply –inventory Platelet supply –inventory Management Management

Platelet Antigen expression Platelet Antigen expression

BackgroundBackground

the effects of 393 transfusions of the effects of 393 transfusions of pooled PLT products in pediatric pooled PLT products in pediatric cancer patients between 1973 and cancer patients between 1973 and 19741974

ABO matching had no effect on the ABO matching had no effect on the success ofsuccess of

a transfusiona transfusionvan Eys J, Thomas D, Olivos B. Platelet use in pediatriconcology: a review of 393 transfusions. Transfusion 1978;18:169-73.

The TRAP trialThe TRAP trial

higher PLT increments after higher PLT increments after transfusion of ABO-compatible PLTs.transfusion of ABO-compatible PLTs.

In lymphoma patients undergoing In lymphoma patients undergoing autologous marrow transplantation, autologous marrow transplantation, leukoreduced ABO identical PLT leukoreduced ABO identical PLT transfusions were associated with transfusions were associated with reduced morbidity ABO-mismatched reduced morbidity ABO-mismatched PLT transfusions may be associated PLT transfusions may be associated with a poor outcomewith a poor outcome

Factors affecting Response to Factors affecting Response to platelets TXplatelets TX

Platelet production Platelet production factorsfactors• Whole blood Whole blood

derived vs. APCderived vs. APC• storage conditions, storage conditions, • storage time, storage time, • PLT yield per PLT yield per

apheresis procedureapheresis procedure• increasing BW of increasing BW of

the recipient the recipient favoured successful favoured successful transfusionstransfusions

Study objective Study objective

The present prospective study was The present prospective study was designed to investigate the impact of designed to investigate the impact of providing either ABO-identical or out-providing either ABO-identical or out-of-group APCs to children with of-group APCs to children with thrombocytopenia suffering from thrombocytopenia suffering from hematologic malignancies, solid hematologic malignancies, solid tumors, or aplastic anemia.tumors, or aplastic anemia.

PATIENTS AND METHODSPATIENTS AND METHODSStudy design and objectivesStudy design and objectives

Differences in transfusion Differences in transfusion efficacy,measured by the 1-hour efficacy,measured by the 1-hour percentage of PLT recovery (PPR1hr)percentage of PLT recovery (PPR1hr)• ABO-identical vs major ABO- mismatched PLTABO-identical vs major ABO- mismatched PLT

Secondary objectives were Secondary objectives were • to compare the efficacy of ABO-identical PLT to compare the efficacy of ABO-identical PLT

transfusions with major mismatched transfusions with major mismatched transfusions of group A subtypes A1 and A2 as transfusions of group A subtypes A1 and A2 as well as with minor-mismatched transfusions well as with minor-mismatched transfusions

side effects of PLT transfusions and data side effects of PLT transfusions and data on the production process of APCs were on the production process of APCs were recorded prospectivelyrecorded prospectively

PatientsPatients 2004-20062004-2006 all consecutive all consecutive

patients with patients with • hematologic hematologic

malignancies, malignancies, • solid tumors, orsolid tumors, or• aplastic anemia aplastic anemia

requiring at least one requiring at least one PLT transfusion PLT transfusion

Exclusion criteria wereExclusion criteria were refusal of studyrefusal of study fever of 38.5°C or fever of 38.5°C or

greater before greater before transfusion,transfusion,

clinically enlarged clinically enlarged spleen,spleen,

thrombosis, thrombosis, Adverse events Adverse events

requiring interruption requiring interruption of transfusion,of transfusion,

Hemorrhage of WHO Hemorrhage of WHO Grade 3 or greaterGrade 3 or greater

Preparation and delivery of Preparation and delivery of PLTsPLTs

PLTs were obtained from healthy volunteer PLTs were obtained from healthy volunteer donors, either by single- or by double-needle donors, either by single- or by double-needle thrombocytapheresis using a cell separator thrombocytapheresis using a cell separator (Amicus Crescendo)(Amicus Crescendo)

single-needle procedures using one of two single-needle procedures using one of two different cell separators (Trima Accel or COBE different cell separators (Trima Accel or COBE Spectra)Spectra)

Depending on the yield, the apheresis product Depending on the yield, the apheresis product was split into units containing at least 2.0 x10 was split into units containing at least 2.0 x10 1111 PLTs, corresponding to the minimum content PLTs, corresponding to the minimum content required by the standards of the Swiss Red Cross required by the standards of the Swiss Red Cross at the timeat the time

Inventory management Inventory management guidelinesguidelines

Older products were delivered first .Older products were delivered first . ABO-identical products were provided first;ABO-identical products were provided first; otherwise minor- or major-mismatched PLTs otherwise minor- or major-mismatched PLTs

were delivered at the discretion of the staff.were delivered at the discretion of the staff. Wherever applicable no D+ PLTs were given to Wherever applicable no D+ PLTs were given to

D– female recipients. D– female recipients. Group O PLT donors were screened for the Group O PLT donors were screened for the

presence of anti-A and anti-B hemolysins. If a titer presence of anti-A and anti-B hemolysins. If a titer of more than 4 was present, the product was of more than 4 was present, the product was labelled accordingly and released for group O labelled accordingly and released for group O recipients onlyrecipients only

PLT transfusionsPLT transfusions

Most patients received prophylactic Most patients received prophylactic PLT transfusions, with only a few PLT transfusions, with only a few receiving PLT transfusions for receiving PLT transfusions for therapeutic purposes.therapeutic purposes.

Children less than 2 years old received Children less than 2 years old received half an APC product, and patients half an APC product, and patients aged 2 years or more received a full aged 2 years or more received a full APC product independent of their BW.APC product independent of their BW.

Efficacy measures: PPR1hr and Efficacy measures: PPR1hr and 1-hour CCI (CCI1hr)1-hour CCI (CCI1hr)

The CCI1hr allows to assess the The CCI1hr allows to assess the efficacy of PLT transfusion efficacy of PLT transfusion accounting for the body surface area accounting for the body surface area (BSA) and the number of transfused (BSA) and the number of transfused PLTsPLTs

PPR1hr [%] = (posttransfusion count PPR1hr [%] = (posttransfusion count [109/L] - pretransfusion count [109/L] - pretransfusion count [109/L]) x blood volume [L]/PLT dose [109/L]) x blood volume [L]/PLT dose [10[101111/L]/L]

Determination of A antigen expression and Determination of A antigen expression and A1/A2A1/A2

subgroup typingsubgroup typing For major-mismatched transfusions from For major-mismatched transfusions from

group A donors, A antigen expression on group A donors, A antigen expression on PLT surfaces was measured by flow PLT surfaces was measured by flow cytometry both in the APC and in the cytometry both in the APC and in the recipient before and 1 hour after recipient before and 1 hour after transfusion.transfusion.

Fluorescent microscopyFluorescent microscopy• to identify glycoprotein IIIa on PLTsto identify glycoprotein IIIa on PLTs

Isohemagglutinin titer testingIsohemagglutinin titer testing• For patients and APCsFor patients and APCs

RESULTSRESULTSPatient characteristics, PLT transfusions, andPatient characteristics, PLT transfusions, and

indicationsindications

Constellations of ABO blood group matching ofConstellations of ABO blood group matching ofdonors and recipientsdonors and recipients

Interim analyses of the primaryInterim analyses of the primarystudy variablestudy variable

The three planned interim analyses The three planned interim analyses did not result in a proposal to stop did not result in a proposal to stop the study early because of proven the study early because of proven difference or proven futilitydifference or proven futility

PLT transfusion efficacyPLT transfusion efficacy The median PPR1hr of all transfusions was 31 The median PPR1hr of all transfusions was 31

percent.percent. Univariate analysis showed PPR1hr for 76 major Univariate analysis showed PPR1hr for 76 major

mismatched transfusions to be significantly mismatched transfusions to be significantly inferior to that for 282 ABO-identical transfusions inferior to that for 282 ABO-identical transfusions (median, 21% vs. 32%; p = 0.034)(median, 21% vs. 32%; p = 0.034)

major-mismatched transfusions were significantly major-mismatched transfusions were significantly more often unsuccessful than ABO-identical more often unsuccessful than ABO-identical transfusions (p = 0.033), especially many major-transfusions (p = 0.033), especially many major-mismatched transfusions from subgroup A1 mismatched transfusions from subgroup A1 donors failed (p = 0.002).donors failed (p = 0.002).

Major-mismatched A2 PLTs were as successful as Major-mismatched A2 PLTs were as successful as ABO-identical ones (p = 1.00ABO-identical ones (p = 1.00

PLT transfusion efficacyPLT transfusion efficacy

Multivariate analysisMultivariate analysis Major-mismatched transfusions were significantly more often Major-mismatched transfusions were significantly more often

unsuccessful than ABO-identical transfusions (p = 0.005).unsuccessful than ABO-identical transfusions (p = 0.005).

subgroup analysis revealed that PLTs from donors with ABO subgroup A2 subgroup analysis revealed that PLTs from donors with ABO subgroup A2 given to group O or B recipients, although major mismatched transfusions, given to group O or B recipients, although major mismatched transfusions, by definition, were just as successful as ABO-identical PLTs (p = 0.90).by definition, were just as successful as ABO-identical PLTs (p = 0.90).

the failure rate of major-mismatched transfusions was even more striking the failure rate of major-mismatched transfusions was even more striking (p = 0.002).(p = 0.002).

Fate of transfused A antigen-positive Fate of transfused A antigen-positive PLTsPLTs

in the majority of group O and B recipients, no A antigen-in the majority of group O and B recipients, no A antigen-positive PLTs were detectable in the circulation 1 hour after positive PLTs were detectable in the circulation 1 hour after transfusion.transfusion.

after ABO-identical PLT transfusions from group A1 donors after ABO-identical PLT transfusions from group A1 donors to group A2 Recipients, whose RBCs but not PLTs express A to group A2 Recipients, whose RBCs but not PLTs express A antigen, the majority of transfused A antigen positive PLTs antigen, the majority of transfused A antigen positive PLTs remained detectable in the circulationremained detectable in the circulation

Fluorescent microscopy of A antigen-positive Fluorescent microscopy of A antigen-positive PLTsPLTs

using the MoAb anti-CD61 for identification of PLTs and using the MoAb anti-CD61 for identification of PLTs and anti-A BRIC-145 for expression of A antigen, depletion of anti-A BRIC-145 for expression of A antigen, depletion of transfused A antigen-positive PLTs from the circulation of a transfused A antigen-positive PLTs from the circulation of a blood group O recipient is visualized at a single-cell level by blood group O recipient is visualized at a single-cell level by dual-color fluorescent microscopydual-color fluorescent microscopy

Regression analysis Regression analysis showed that for group showed that for group A major-mismatched A major-mismatched transfusions, there transfusions, there was a significant was a significant negative correlation (p negative correlation (p = 0.002) between the = 0.002) between the percentage of A percentage of A antigen-positive PLTs antigen-positive PLTs in the APC and the in the APC and the PPR1hr; that is, the PPR1hr; that is, the more PLTs expressed more PLTs expressed A antigen, the lower A antigen, the lower the PPR1hrthe PPR1hr

Safety review and isohemagglutinin Safety review and isohemagglutinin titerstiters

no clinically detectable hemolytic transfusion reaction was no clinically detectable hemolytic transfusion reaction was observed.observed.

no association between transfusion efficacy and the no association between transfusion efficacy and the recipient’s isohemagglutinin titers were detected (data not recipient’s isohemagglutinin titers were detected (data not shown)shown)

DISCUSSIONDISCUSSION ABO-incompatible PLTs may be associated with ABO-incompatible PLTs may be associated with

decreased PLT increments after transfusion.decreased PLT increments after transfusion. The majority of studies have been performed in The majority of studies have been performed in

adult patients, and PLT transfusion in children is adult patients, and PLT transfusion in children is poorly investigatedpoorly investigated

A randomized study design would have increased A randomized study design would have increased the power of the study. However, in view of the the power of the study. However, in view of the preceding studies in adults it is considered such preceding studies in adults it is considered such a design incompatible with good clinical practice a design incompatible with good clinical practice in this vulnerable pediatric population.in this vulnerable pediatric population.

DISCUSSIONDISCUSSION

statistical endpoints is based on CCI1hr statistical endpoints is based on CCI1hr and PPR1hr as surrogate parameters for and PPR1hr as surrogate parameters for PLT transfusion efficacyPLT transfusion efficacy

CCI1hr accounts for BSA and is well CCI1hr accounts for BSA and is well established in adults, whereas PPR1hr established in adults, whereas PPR1hr accounts for BW and is reported to be accounts for BW and is reported to be more appropriate in children, particularly more appropriate in children, particularly in infants and toddlers.in infants and toddlers.

The final analysis was based on PPR1hr.The final analysis was based on PPR1hr.

DISCUSSIONDISCUSSION

The results demonstrate that The results demonstrate that transfusion efficacy and transfusion transfusion efficacy and transfusion success, the latter defined as PPR1hr success, the latter defined as PPR1hr of more than 30 percent, of major-of more than 30 percent, of major-mismatched PLTs are significantly mismatched PLTs are significantly inferior to those of ABO-identical inferior to those of ABO-identical PLTs, whereas efficacy and success PLTs, whereas efficacy and success of minor-mismatched transfusions of minor-mismatched transfusions are not different from those of are not different from those of identical transfusions.identical transfusions.

DISCUSSIONDISCUSSION diversity in the percentages of PLTs expressing A diversity in the percentages of PLTs expressing A

antigen among A1 donors (median, 40%; range, antigen among A1 donors (median, 40%; range, 3%-80%).3%-80%).

the percentage of A antigen-expressing PLTs and the percentage of A antigen-expressing PLTs and PPR1hr were inversely related; that is, the higher PPR1hr were inversely related; that is, the higher the percentage of A antigen-expressing PLTs, the the percentage of A antigen-expressing PLTs, the lower the PPR1hr.lower the PPR1hr.

Median anti-A titers in the plasma of blood group Median anti-A titers in the plasma of blood group O recipients was higher than in plasma of group B O recipients was higher than in plasma of group B recipients , this may explain the slightly better recipients , this may explain the slightly better survival of transfused A1 PLTs in group B survival of transfused A1 PLTs in group B recipients recipients

A2 PLTs can be considered group O compatibleA2 PLTs can be considered group O compatible

Critical Appraisal Critical Appraisal

Prospective observational study .Prospective observational study . Were all patients who entered the trial Were all patients who entered the trial

properly accounted for at its conclusion?properly accounted for at its conclusion? Will the results help me in caring for my Will the results help me in caring for my

patients?patients? Can the results be applied to my patient Can the results be applied to my patient

care?care? Were all clinically important outcomes Were all clinically important outcomes

considered?considered?

ConclusionConclusion

major-mismatched PLT transfusions major-mismatched PLT transfusions were significantly less successful were significantly less successful than ABO-identical transfusions.than ABO-identical transfusions.

In children requiring regular and In children requiring regular and continued PLT support, an ABO-continued PLT support, an ABO-compatible transfusion strategy compatible transfusion strategy should be the first choice.should be the first choice.

PLT concentrate suppliers would PLT concentrate suppliers would have to provide A1/A2 subgroup have to provide A1/A2 subgroup typing of group A PLT donorstyping of group A PLT donors

Conclusion Conclusion

In this study, transfusion of plasma-In this study, transfusion of plasma-incompatible PLTs was as successful incompatible PLTs was as successful as that of identical PLTs, although an as that of identical PLTs, although an inherent risk for hemolytic inherent risk for hemolytic transfusion reactions will remaintransfusion reactions will remain

To volume reduce or not?To volume reduce or not? Will blood supplier or hospital test Will blood supplier or hospital test

donor for high titer Anti A once and donor for high titer Anti A once and for all ?for all ?