FAQ: Information for health professionals on apheresis platelet psoralen-treated (APPT) and untreated apheresis platelet in PAS-E

Authors: Shuoyan Ning, MD, FRCPC, DRCPSC; Amanda Nowry, BSc, MLT; Michelle Zeller, MD, FRCPC, DRCPSC


NOTE: This information reflects evidence available at time of publication. Please consult Canadian Blood Services' Circular of Information (COI) on APPT and untreated apheresis platelet in PAS-E (COIs available as of June 12, 2023), as well as Chapter 19 of the Clinical guide to transfusion for more information including additional resources (slide decks, narrated videos, animations). 
 

Background

The implementation of pathogen-reduced platelet components began with Pooled Platelet Psoralen-Treated (PPPT) in Ottawa in January 2022; as of June 2023, PPPT continues to roll-out to hospitals across the country. Following Health Canada approval in May 2023, Apheresis Platelet Psoralen-Treated (APPT) and untreated apheresis platelet in PAS-E are being implemented in Ottawa on June 12, 2023, with a national implementation to follow (see Customer Letter CL 2023-03). 

APPT, like PPPT, are pathogen-reduced platelets that do not require irradiation prior to transfusion. The technology used for pathogen inactivation, component administration, and clinical use are the same for APPT as PPPT. Untreated apheresis platelet in PAS-E are not pathogen-reduced and will be available to order for limited indications. 

This FAQ has been developed to assist hospitals in implementing APPT and untreated apheresis platelet in PAS-E. 

General

1. How do component characteristics for pathogen-reduced platelets (specifically apheresis platelet psoralen-treated or APPT) compare to untreated platelets?

See Table 1 for a comparison of component characteristics (this table is excerpted from Chapter 19 of the Clinical guide to transfusion).

Table 1: Component characteristics of pathogen-reduced and untreated platelets

Component characteristic Untreated pooled platelet Untreated apheresis platelet Untreated apheresis platelet in PAS-E Apheresis platelet psoralen-treated (APPT) Pooled platelet psoralen-treated (PPPT)
  Untreated (not pathogen-reduced) Pathogen-reduced
Mean unit volume (mL) 317 223 269 277 184
Number of donors in component 4 1 1 1 7
Mean plasma volume (mL) 317 (approximately 20 mL for 3 donors and + 257 mL plasma from one male donor) 173 113 116 75 (approximately 11 mL per donor)
Approximate platelet count
(x109 platelets per L)
1,069 1,493 1033 909 1,363
Approximate platelet yield
(x109 platelets per unit)
339 333 279 252 251
Resuspension solution Plasma Plasma Approx. 60% Platelet Additive Solution (PAS-E)
+ 40% plasma
Approx. 60% Platelet Additive Solution (PAS-E)
+ 40% plasma
Approx. 60% Platelet Additive Solution (PAS-E)
+ 40% plasma
Anticoagulant CPD ACD-A ACD-A ACD-A CPD
Bacterial screening performed by Canadian Blood Services Yes Yes Yes No No
Typical time to release component to hospital after blood collection from donor Day 3 Day 3 Day 3 Day 2 Day 2
Component shelf life (from day of blood collection) 7 days 7 days 7 days  7 days 7 days*
Viable lymphocytes present?  Yes, irradiation required for vulnerable patients¥ Yes, irradiation required for vulnerable patients¥ Yes, irradiation required for vulnerable patients¥ Viable lymphocytes not present, irradiation not required for vulnerable patients. Viable lymphocytes not present, irradiation not required for vulnerable patients.

‡ PPPT components are manufactured from 7 donor (male or female) buffy coats, which are pooled together and then divided into 2 separate units for transfusion. Note the lower platelet yield of the PPPT component compared to the untreated pooled platelet component. 

* The shelf life of PPPT was increased from 5 to 7 days on April 24, 2023.

¥ See the National Advisory Committee on Blood and Blood Products’ Recommendations for Use of Irradiated Blood Components in Canada.1

APPT

2. What is the technology used for pathogen-reduced platelet components, and how does it work?

Canadian Blood Services uses the INTERCEPT Pathogen Inactivation Technology by Cerus to treat platelets. This technology uses a psoralen compound (amotosalen) and ultraviolet (UV) light to cause irreversible damage to genetic material present in pathogens, rendering them inactive.

3. Will apheresis platelets psoralen-treated (APPT) completely replace untreated pooled platelets?

Once APPT are implemented at a Canadian Blood Services site, the current untreated apheresis platelet component will no longer be produced by that site. Untreated apheresis in PAS-E will be available to order for limited indications. Please see question 12.

4. Could APPT be released to my hospital before my production site implements them?

Yes, this is possible. Canadian Blood Services manages a national platelet inventory so hospitals could receive APPT even though their local Canadian Blood Services site has not yet implemented the manufacturing of this component.   

5. Could untreated apheresis platelets be released to my hospital after my production site implements APPT?

Yes, this is possible. Canadian Blood Services manages a national platelet inventory. It is possible that hospitals may receive untreated components to meet inventory demands as APPT production rolls out.

6. Can we order both units of APPT originating from the same parent unit? 

Yes, a paired dose can be issued to a hospital, if specifically requested and if available (e.g., a double dose apheresis platelet unit was collected). Standard platelet orders will be issued by the oldest expiry, unless otherwise indicated. If a single dose apheresis platelet unit was collected, then this would not be possible.

7. What will happen to HLA and HPA matched platelets? 

The majority of HLA and HPA matched platelets will be pathogen inactivated. Untreated apheresis platelets in PAS-E that are HLA or HPA matched are available to order for limited indications. Please see question 12.

8. Can aliquots be obtained from an APPT unit for transfusion? What is the minimal residual volume of an APPT unit?

Yes, aliquots can be obtained if there is a minimal residual volume of 135 mL in the platelet bag. In other words, once there is 135 mL or less remaining in the platelet bag, the platelet component can no longer be used and no further aliquots can be obtained.

9. Do untreated (apheresis or pooled) platelet components have the same concentration as APPT?

No, untreated platelet components are more concentrated than APPT. The platelet yield (number of platelets in the bag) is comparable between PPPT, APPT, and untreated apheresis platelet in PAS-E. Please see Table 1 for more information.

10. Is the tail on the APPT unit long enough to allow docking to another bag?

Yes, once the bulb is removed, the remaining tubing length is approximately 8 cm. This should be sufficient for docking on another bag depending on the tube welder device used. 

Untreated apheresis platelet in PAS-E

11. When might non pathogen-reduced platelets (i.e., untreated apheresis platelet in PAS-E) be needed?  

As Canadian Blood Services transitions to a pathogen-reduced national platelet inventory, untreated apheresis platelets in PAS-E will be available for limited indications. These indications include intra-uterine transfusions (as there is no published clinical data on pathogen-reduced platelets for these populations), and patients with a history of hypersensitivity reactions to amotosalen or other psoralen products.

Pathogen-reduced platelets are not indicated for neonatal patients treated with phototherapy devices that emit a peak energy wavelength less than 425 nm or have a lower bound of the emission bandwidth less than 375 nm. However, in Canada, phototherapy in the blue-green light with peak wavelength of 450–460 nm (safe range) is the current standard of care for treatment of neonatal hyperbilirubinemia.2,3

12. How can hospitals order untreated apheresis platelet in PAS-E?

Hospitals can order untreated apheresis platelet in PAS-E via the Special Request Order Form from blood.ca, as well as by contacting the hospital’s local Canadian Blood Services Distribution department.

As these platelets are non-pathogen inactivated, they require bacterial testing. Canadian Blood Services will require a minimum of 3 days to fulfill these orders. 

13. Can aliquots be obtained from an untreated apheresis platelet in PAS-E unit for transfusion? What is the minimal residual volume of an untreated apheresis platelet in PAS-E unit?

Yes, aliquots can be obtained if there is a minimal residual volume of 100 mL in the platelet bag. In other words, once there is 100 mL or less remaining in the platelet bag, the platelet component can no longer be used and no further aliquots can be obtained.

14. Do untreated apheresis platelet in PAS-E have the same concentration as pathogen-reduced platelets?

No, untreated apheresis platelet in PAS-E components are less concentrated (numbers of platelets/L) than PPPT and of comparable concentration to APPT. The platelet yield (number of platelets in the bag) is comparable between PPPT, APPT, and untreated apheresis platelet in PAS-E. Please see Table 1 for more information.

15. Will cytomegalovirus (CMV) negative platelet components remain available for intrauterine transfusion (IUT)?

Yes, CMV negative untreated apheresis platelet in PAS-E for intrauterine transfusion will be available from Canadian Blood Services.

References

  1. National Advisory Committee on Blood and Blood Products. Recommendations for use of irradiated blood components in Canada.  (2018).

  2. Ebbesen, F., Donneborg, M.L., Vandborg, P.K., et al. Action spectrum of phototherapy in hyperbilirubinemic neonates. Pediatric research (2021).

  3. Barrington KJ, S.K., Canadian Paediatric Society, Fetus and Newborn Committee. Guidelines for detection, management and prevention of hyperbilirubinemia in term and late preterm newborn infants (35 or more weeks' gestation) - Summary. Paediatr Child Health 12, 401-418 (2007).