key: cord-1036472-zidy31kh
authors: Valentini, Caterina Giovanna; Chiusolo, Patrizia; Bianchi, Maria; Metafuni, Elisabetta; Orlando, Nicoletta; Giammarco, Sabrina; Bacigalupo, Andrea; Sica, Simona; Teofili, Luciana
title: COVID-19 PANDEMIC AND ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION: A SINGLE CENTER REAPPRAISAL
date: 2020-12-11
journal: Cytotherapy
DOI: 10.1016/j.jcyt.2020.12.001
sha: 049014cc4d8755d37a99a3ad3fa98c131791b5cd
doc_id: 1036472
cord_uid: zidy31kh

COVID-19 pandemic has deeply modified the complex logistic process underlying allogeneic hematopoietic stem cell (HSC) transplant practices. We compared data relative to allogeneic transplants carried out from 2018 at our center, before (n=167) or during the pandemic (n=45). We examined patient's characteristics, donor and graft types, cell doses and main transplant outcomes. Moreover, we appraised the rise of costs attributable to COVID-19-related additional procedures, as well as the risk for adverse events that these procedures conveyed to grafts or recipients. Overall, the number of transplants did not decrease during pandemic, whereas patients at high relapse risk were prioritized. Transplants were mainly from matched unrelated donors, with a significant decrease of haploidentical related donors. Moreover, the use of bone marrow as a graft for haplo-transplant was almost abandoned. Cryopreservation was introduced for all related and unrelated apheresis products, with a median storage time of 20 days. Notably, transplant outcomes (engraftment, acute graft versus host disease and non-relapse mortality) with cryopreserved products were comparable to those with fresh products. Considering that the emergency situation may persist for months, to cryopreserve allogeneic grafts can offer a lifesaving opportunity to patients whose allogeneic transplant cannot be postponed after the end of the COVID-19 pandemic.

The emergence of the coronavirus disease 2019 (COVID-19) pandemic has triggered an exceptional worldwide healthcare crisis. Italy has been among the first nations in Europe where COVID-19 broke out. On January 27, the National Transplant Center in Italy issued the first warning about SARS-CoV-2 infection and HSC donation. 1 On February 24, the requirement for SARS-CoV-2 donor screening was introduced, first in the COVID-19 high-risk districts, and a few days later in the entire national area. 2 Since March 13, Italian transplant centers were strongly recommended by the competent authority to start the conditioning regimen in recipients only after HSC products either from related or unrelated donors had been delivered and cryopreserved. 3 The same recommendations were issued by the European Society for Blood and Marrow Transplantation (EBMT). 4 Altogether, the COVID-19 pandemic has deeply modified the complex allograft logistic process at multiple stages. On one hand, it is conceivable that travel restrictions within and across countries, as well as the disease itself or the quarantine following SARS-CoV-2 exposure, could make more difficult to access hematopoietic stem cell (HSC) donors, either related or unrelated. On the other hand, the graft collection that before the pandemic was strictly organized depending on the conditioning regimen of the recipient has been managed with a more flexible approach thanks to cryopreservation. 5 Due to concerns about the negative impact of freezing and thawing on the viability of hematopoietic stem cells, until now we use to infuse allogeneic HSC products soon after the collection, whereas only a minimal proportion of grafts have been exceptionally cryopreserved.

Because of all these considerations, we revised our data to enlighten the effect of the ongoing COVID-19 pandemic on our allogeneic transplant practices. To this end, we compared the number and types of procedures of allograft cryopreservation carried out in pre-pandemic and pandemic periods. We examined cell doses and main transplant outcomes in patients receiving cryopreserved grafts. Moreover, we appraised the rise of costs attributable to COVID-19-related additional procedures, as well as the risk for adverse events that they conveyed to grafts or recipients. Patients' variables included demographics, diagnosis, status of the disease at transplant (complete remission or not), disease risk index (DRI), 6 hematopoietic cell transplantation comorbidity index (HCT-CI), 7 incidence of acute graft versus host disease (aGVHD) 8 and death. Graft variables were: source (bone marrow, BM or peripheral blood stem cells, PBSC), total nucleated cell (TNC) content, CD34+ cell content, CD3+ cell content, CD34+cell viability assessed either freshly, or freshly and post-freezing in cryopreserved products. Cell contents were expressed as cell dose (i.e. the number of cells per kg of the recipient's body weight) and were obtained as previously reported. 9 5 Study endpoints and definitions. We analyzed according to the transplant period (COVID-19 or pre-COVID-19) the characteristics of donors (demographics and country), recipients (demographics and disease-related data) and grafts (PBSC or BM) We analyzed in transplants performed with fresh or cryopreserved grafts the following endpoints: TNC and CD34+ cell doses; cumulative incidence of neutrophil engraftment (i.e. the day of achievement of an absolute neutrophil count (ANC) ≥ 0.5x10 9 /L); cumulative incidence of platelet engraftment (i.e. the day of achievement of a platelet count ≥ 20x10 9 /L unsupported by transfusion); reticulocyte recovery (i.e. a reticulocyte count above 2.7%); cumulative incidence of aGVHD (grades II-IV); non-relapse mortality 

Two-hundred and twelve consecutive transplants from adult donors were included in the study. Although there was no difference regarding age, gender or diagnosis, patients transplanted during COVID-19 showed higher DRI and lower HCT-CI scores (Table 1) . SARS-CoV-2 screening by PCR on nasopharyngeal swabs (with or without serology) was performed in all donors from March 2020 onward. Thirty-five (19 unrelated and 16 related) donors were screened. No positive donors were found.

Transplant distribution before and during the COVID-19 period.

Graft and donor characteristics of transplants performed before and during the COVID-19 pandemic are shown in Table 2 . Allogeneic HSC transplant activities at our center were not slowed by pandemic, varying from a mean of 6.8 to 5.6 transplants per month (p=0.7334). We observed a relative increase of transplants from unrelated donors (from 34.7% to 55.6%, p= 0.0155). As compared with the previous period, during the pandemic the proportion of donations from European countries (96.0% versus 70.7%, p=0.0103) increased. Overall, fewer transplants from haploidentical familial donors were performed (from 39.5% to 15.5%, p= 0.0025). This resulted from the drastic decrease of BM harvesting procedures usually performed at our center in the pre-COVID-19 era (from 41.3% to 11.1% of all grafts, p<0.0001). In addition, haploidentical transplants before the pandemic were frequently carried out in patients with chronic myeloproliferative neoplasms, lymphomas or multiple myeloma. In contrast, during the pandemic, the transplant of patients with chronic disease was postponed whenever possible (Table 1) . As a result, 6 out of 7 patients (85,7%) receiving haploidentical transplant during the pandemic were affected by acute myeloid leukemia. In addition, PBSC instead of BM grafts were harvested from haploidentical donors, to secure the transplant to more urgent cases of patients with high-risk disease. Thirty-two out of 212 grafts underwent cryopreservation and storage before transplant, with a median storage duration of 20 days (IQR 12-26): all of them were PBSC grafts and 31 had been collected during pandemic (Table 2) .

We included in the analysis the 31 PBSC grafts cryopreserved from March 2020 onward, and one related PBSC product cryopreserved in 2019 to bring forward the donation upon the donor request. Table 3 shows patient's and graft characteristics of allogeneic transplants performed with fresh or cryopreserved products. Donor-and recipient-related variables were similar in fresh and cryopreserved products. Although patients transplanted with cryopreserved products seemed to be given slightly lower TNC doses than those infused with fresh products, they received similar CD34+ cell doses.

Cryopreservation resulted in a slight loss of viable CD34+ cells, decreasing from 7.1•10 6 /Kg (IQR 5.4-8.8) to 6.2•10 6 /Kg (IQR 4.9-8.2) (p<0.0001), as evaluated based on CD34+ cell viability at thawing. Despite that, fresh and cryopreserved grafts contained similar CD34+ cell doses. The estimated cumulative incidence of engraftment at day +30 in patients in the "fresh" or "cryopreserved" groups were 89.6% (95% CI 84.0-95.6) and 96.7% (95% CI 90.7-100) for neutrophils (p=0.8393), and 76.4% (95% CI 68.7-84.9) and 80.4% (95% CI 67.6-95.7) for platelet (p=0.5613), respectively. Similarly, there was no difference regarding the reticulocyte recovery (p=0.6101). ( Figure 1A ). Seventeen patients in the "fresh" group and 5 in the "cryopreserved" group developed grade II-IV aGVHD. The day +100 cumulative incidence of grade II-IV aGVHD in "fresh" or "cryopreserved" groups were 19.5% (95%CI 12.6-30.1) and 23.8% (95%CI 9.7-58. Additional costs.

Cryopreservation due to COVID-19-related measures resulted in additional costs due to the procedure itself, microbial cultures, and viability tests performed on cryopreserved units before the release. Table 4 shows direct costs that we calculated based on the mean technician hour-work and consumables and disposables requirement for one cryopreservation. Overall, every cryopreservation resulted in an additional cost of 382.62 Euro, corresponding to an overall expense of 12,244 Euro.

COVID-19 pandemic led the transplantation community to face exceptional challenges to avoid postponing this life-saving procedure, in the meanwhile assuring the 9 absolute safety to donors and recipients. In this study, we revised data relative to allogeneic HSC transplantations performed at our center in the pandemic period, to understand how our daily practices changed to fulfill requirements presented by the COVID-19.

Despite an increased complexity in the whole process of donor procurement, workout, and graft harvesting, the sprouting of the pandemic was not associated with a decline of allogeneic transplants at our institution. Our data emphasize that during the pandemic patients at higher relapse risk were given the priority. Likewise, the increased COVID-19 mortality in general people with multiple comorbidities, 11 led to prioritize patients with lower HCT-CI scores. A similar approach has been reported by the Seattle transplant group. 12 The authors developed an algorithm guiding the temporary deferral of transplants deemed nonurgent based on the risk of the underlying malignancy. Indeed, patients were prioritized according to both the risks of recurrence or progression of the malignancy and burden of comorbidity. 12 Overall, the pandemic significantly influenced the criteria adopted to select donors, as well as modified the types of stem cell sources. Paralleling the lockdown measures progressively introduced in Italy from mild February, transplants from related donors decreased in favor of those from unrelated donors. Multiple reasons can account for this finding. Before the pandemic, we used to perform transplants from haploidentical donors using BM as a stem cell source, due to the concern of the higher incidence of acute and chronic GVHD reported in PBSC haploidentical transplants. [13] [14] [15] Nevertheless, at the onset of the pandemic our hospital was designed as a dedicated COVID -19 center in Rome, leading to the rearrangement of many departments and the establishment of COVID-19 dedicated pathways, including surgery rooms. Therefore, BM harvesting was challenged by increased difficulties in logistics for donor hospital admission, surgery room availability, and management of COVID-19 related infectious risk. Moreover, fewer patients with chronic diseases, who were frequent candidates to haploidentical transplant before the pandemic, were transplanted in the COVID-19 period. Consequently, priority was given to HLA-matched related and unrelated donors, while for patients with no registry donor, haplo-transplant were performed with PBSC as a graft. Indeed, registry donors represented to our patients a highly reliable resource, even more in the pandemic period.

Border closures, difficulties related to flight cancellation prompted the tendency to select donors from European registries, allowing organizing last-minute product transport on wheels.

The most remarkable change in our practices in consequence of COVID-19 pandemic was to extend cryopreservation to allogeneic PBSC grafts. Actually, until pandemic, we cryopreserved only autologous products, unless it was impossible to postpone donation for exceptional reasons due to donors or recipients. The cryopreservation was first introduced to prevent possible delay of unrelated product delivery, whereas it was rapidly adopted also for related grafts. In fact, it allowed a more comfortable management of the hospital admission of recipients, as well as the postdonation follow-up of the donor. One of the main concern related to cryopreservation is represented by the loss of viable cells due to unit processing or during the storage. 16, 17 This risk may be exacerbated if products are cryopreserved at cell concentration greater than 2x10 8 /ml, or if they contain a large amount of granulocytes. [18] [19] [20] In this study, we confirmed that part of viable CD34 + cells was lost with cryopreservation. Nevertheless, it deserves to be emphasized that our data were achieved on one single satellite vial, and results were no further confirmed on attached segments. In addition, we estimated CD34+ cell viability but not CD34+ cell potency, since we did not carry out the colony-forming unit assay on our samples. Despite these limitations, the loss was negligible and did not significantly affect either the CD34+ cell dose or the hematopoietic recovery. Thus, our data confirm previous observations on allogenic transplants performed with cryopreserved 11 products, suggesting that it is a safe and feasible procedure. [21] [22] [23] [24] [25] [26] In fact, previous studies comparing transplant outcomes in patients receiving fresh or cryopreserved grafts globally back cryopreservation also in the allogeneic scenario. [21] [22] [23] [24] [25] [26] Nonetheless, this might not be true in every clinical setting. In particular, Eapen et al. have recently reported an increased incidence of graft failure and 1-year mortality in SAA patients receiving cryopreserved grafts. 27 Given the short follow-up of patients transplanted with cryopreserved grafts at our center, we could explore only short-term transplant outcomes. Overall, our data do not show difference regarding the incidence of engraftment, aGVHD and NRM in comparison with patients receiving fresh grafts, whereas longer follow-up are necessary to assess if cryopreserved and fresh transplants elicit superimposable results regarding chronic GVHD, disease-free and overall survival.

From the ethics perspective, the most important concern raised against cryopreservation is that, in exceptional circumstances related to the recipient (i.e. sudden worsening or death), the harvested product might be not transplanted. 16, 24 In the present study, we found that all cryopreserved products were transfused, and the median storage duration was 20 days. This finding is in agreement with the high relapse risk of our patients, and shows that at least in our experience, graft collection was strictly finalized to the transplant, while cryopreservation allowed a flexible management of recipient hospital admission.

The policy to cryopreserve regularly the allogenic grafts undoubtedly conveys additional expenses to the hospital. Considering the disease-related-group reimbursement operated by the Italian National Health System to public hospitals, these costs can be considered marginal. Nonetheless, cryopreservation implies also additional risks related to the unit processing, such as risk of bag damaging, and possible microbial contamination, and infusion reactions from DMSO. 16, 24 We did not observe adverse reactions among patients receiving cryopreserved products, but we experienced the failure 12 of the controlled rate cooling freezer during the processing of one unrelated PBSC unit.

Fortunately, in our case, the failure did not affect the product quality. Nevertheless, this episode suggests that both donors and recipients should be made aware for these cryopreservation drawbacks, possibly requiring to arrange further donations. We also recorded the microbial contamination of one PBCS product, likely occurred during the processing. Notably, before the pandemic, we had to cope with similar problems only with BM grafts, whose contamination likely occurred during the harvesting procedure.

In conclusion, our experience regarding allogeneic transplants with cryopreserved products suggests that it is a feasible and safe option, allowing to comply with all precautions imposed by pandemic. 24 After the transient pandemic control during summer, several donor registries returned to normal procedures, and freezing products was no longer recommended considering the several reports of cryopreserved products never infused. 17 Presently, however, donors in many countries face a high risk for SARS-CoV-2 infection between work-up and collection, and pre-planned cryopreservation is recommended. 28 Considering that this emergency situation may persist for months, to 

Correction: The challenge of COVID-19 and hematopoietic cell transplantation: EBMT recommendations for management of hematopoietic cell transplant recipients, their donors, and patients undergoing CAR T-cell therapy

Real-World Issues and Potential Solutions in Hematopoietic Cell Transplantation during the COVID-19 Pandemic: Perspectives from the Worldwide Network for Blood and Marrow Transplantation and Center for International Blood and Marrow Transplant Research Health Services and International Studies Committee

Validation and refinement of the Disease Risk Index for allogeneic stem cell transplantation

Hematopoietic cell transplantation (HCT)-specific comorbidity index: a new tool for risk assessment before allogeneic HCT

Consensus Conference on Acute GVHD Grading

Bone marrow haploidentical transplant with post-transplantation cyclophosphamide: does graft cell content have an impact on main clinical outcomes?

Prevalence of Underlying Diseases in Hospitalized Patients with COVID-19: a Systematic Review and Meta-Analysis

Blood and marrow transplantation during the emerging COVID-19 pandemic: the Seattle approach

Mobilized Peripheral Blood Stem Cells Versus Unstimulated Bone Marrow As a Graft Source forT-Cell-Replete Haploidentical Donor Transplantation Using Post-Transplant Cyclophosphamide

Bone marrow versus mobilized peripheral blood stem cells in haploidentical transplants using posttransplantation cyclophosphamide

CD3+ graft cell count influence on chronic GVHD in haploidentical allogeneic transplantation using post-transplant cyclophosphamide

Securing the graft during pandemic: are we ready for cryopreservation for all?

The influence of cell concentration at cryopreservation on neutrophil engraftment after autologous peripheral blood stem cell transplantation

Quantifying loss of CD34+ cells collected by apheresis after processing for freezing and post-thaw

Graft Composition and Post-Thawing Cell Viability Influence the Hematopoietic Recovery in Autologous Hematopoietic Stem Cell Transplantation

Has allogeneic stem cell cryopreservation been given the 'cold shoulder'? An analysis of the pros and cons of using frozen versus fresh stem cell products in allogeneic stem cell transplantation

Similar outcomes of cryopreserved allogeneic peripheral stem cell transplants (PBSCT) compared to fresh allografts

Graft Cryopreservation Does Not Impact Overall Survival after Allogeneic Hematopoietic Cell Transplantation Using Post-Transplantation Cyclophosphamide for Graftversus-Host Disease Prophylaxis

Cryopreservation for All Is No Option in Unrelated Stem Cell Transplantation. Comment on Dholaria B, et al. Securing the Graft During Pandemic: Are We Ready for Cryopreservation for All?

Variable CD34+ recovery of cryopreserved allogeneic HPC products: transplant implications during the COVID-19 pandemic

Cryopreservation of allogeneic PBSC from related and unrelated donors is associated with delayed platelet engraftment but has no impact on survival

Hematopoietic Cell Transplantation with Cryopreserved Grafts for Severe Aplastic Anemia