Graft failure after allogeneic hematopoietic stem cell transplantation in pediatric patients with acute leukemia: autologous reconstitution or second transplant?

BACKGROUND

Graft failure (GF) is a rare but serious complication after allogeneic hematopoietic stem cell transplantation (HSCT). Prevention of graft failure remains the most advisable approach as there is no clear recommendation for the best strategies for reversing this complication. Administration of growth factor, additional hematopoietic progenitor boost, or a salvage HSCT are current modalities recommended for the treatment of GF. Autologous recovery without evidence of disease relapse occurs rarely in patients with GF, and in the absence of autologous recovery, further salvage transplantation following a second conditioning regimen is a potential treatment option that offers the best chances of long-term disease-free survival. The preconditioning regimens of second HSCT have a significant impact on engraftment and outcome, however, currently there is no consensus on optimal conditioning regimen for second HSCT in patients who have developed GF. Furthermore, a second transplant from a different donor or the same donor is still a matter of debate.

OBSERVATIONS

We present our experience in managing pediatric patients with acute leukemia who encountered graft failure following stem cell transplantation.

CONCLUSIONS AND RELEVANCE

Although a second transplantation is almost the only salvage method, we illustrate that some pediatric patients with acute leukemia who experience graft failure after an allogeneic stem cell transplant using Myeloablative conditioning (MAC) regimen may achieve long-term disease-free survival through autologous hematopoiesis recovery.

Sustained Hematopoietic Engraftment Potential after Prolonged Storage of Cryopreserved Hematopoietic Stem Cells (HSC) Used in Salvage Autologous Stem Cell Transplantation: Prolonged Storage of HSCs Sustains Hematological Reconstitution Potential

BACKGROUND

Salvage autologous hematopoietic stem cell transplantation (HSCT) is an effective treatment for patients with relapsed multiple myeloma (MM). Peripheral blood stem cells (PBSCs), a source of hematopoietic stem cells (HSCs), are collected prior to first transplant and adequate quantities of PBSCs can be collected and stored potentially for years to support at least two transplants for eligible patients. To ensure the safety of salvage HSCT used in the treatment of patients in subsequent relapse, PBSCs must retain the potential to engraft even after several years of cryopreservation. Although PBSC viability has been extensively studied using in vitro techniques, few publications describe the most rigorous functional potency measure: of patients receiving a myeloablative conditioning regimen. This study describes a large single-institution experience evaluating the engraftment kinetics of PBSCs used in salvage transplantation after multiple years of storage in comparison to first transplantation of the same patients in the treatment of MM.

STUDY DESIGN AND METHODS

A retrospective chart review of patients with MM undergoing HSCT from 2000 to 2021, identified 89 patients who received salvage autologous PBSC stored > 1 year after first HSCT. PBSC were cryopreserved and stored in vapor-phase liquid nitrogen refrigerators at a temperature of ≤ -150°C. All patients received a PBSC product for both transplants from the same collection cycle. Differences in CD34⁺ cell doses and days to engraftment between the first and salvage transplant were tested using a paired 2-tailed t-test and Wilcoxon signed-rank test. Univariate and multivariable linear regressions were used to determine association between storage time and days to engraftment, adjusting for CD34+ cell dose and conditioning regimen in the multivariable model.

RESULTS

The median storage time between day of initial collection and salvage transplant was 5.4 years (range, 1.0 - 19.7). Engraftment kinetics demonstrated a sustained neutrophil engraftment (absolute neutrophil count (ANC) > 0.5 × 10⁹ cells/L) at a median of 11 days after both the first and salvage transplant (ranges, 8 - 15 and 8 - 19 respectively, p<0.05). The median time to sustained platelet engraftment (> 20 × 10⁹ cells/L without transfusion support) was 13.5 days after first HSCT and 14 days after salvage HSCT (ranges, 9 - 27 and 10 - 56 respectively, p = 0.616). After adjusting for CD34+ cell doses and conditioning regimens, there was no association between the duration of cryopreservation and days to neutrophil (r = 0.178, p = 0.130) or platelet (r = 0.244, p = 0.100) engraftments.

CONCLUSION

Engraftment kinetics of the salvage HSCT are comparable to the first HSCT even when products are stored in vapor-phase nitrogen refrigerators for a median time of 5.4 years. There is no association between storage duration and time to engraftment when controlling for CD34+ dose and conditioning regimens. Prolonged storage of cryopreserved HSC products is a safe practice for MM patients undergoing salvage autologous HSCT.

Use of Backup Stem Cells for Stem Cell Boost and Second Transplant in Patients with Multiple Myeloma Undergoing Autologous Stem Cell Transplantation

Autologous hematopoietic stem cell transplantation (ASCT) is a standard treatment for multiple myeloma (MM). Consensus guidelines recommend collecting sufficient stem cells in case there is a need for stem cell boost for delayed/poor engraftment or for future second ASCT. However, collecting and storing backup stem cells in all patients requires significant resources and cost, and the rates of backup stem cell utilization are not well studied. We sought to examine the utilization of backup stem cells (BSCs) in patients with MM undergoing ASCT. Patients with MM aged ≥18 years old who underwent first ASCT at our institution from January 2010 through December 2015 and collected sufficient stem cells for at least 2 transplants were included in this single-center retrospective study. This timeframe was selected to allow for adequate follow-up. A total of 393 patients were included. The median age was 58 years (range, 25-73). After a median follow-up of 6 years, the median progression-free survival (PFS) of the cohort was 3 years. Sixty-one percent (n = 240) of patients progressed or relapsed. Chemotherapy-based mobilization was used in almost all patients (98%). The median total CD34+ cells collected was 18.2 × 106/kg (range, 3.4-112.4). A median of 5.7 × 106 CD34+ cells/kg (range, 1.8-41.9) was infused during the first ASCT, and a median of 10.1 × 106 CD34+ cells/kg (range, 1.5-104.5) was cryopreserved for future use. Of the patients, 6.9% (n = 27) used backup stem cells, with 2.3% (n = 10) using them for stem cell boost, 4.6% (n = 18) for a second salvage ASCT, including 1 patient for both stem cell boost and second ASCT. Rates of backup stem cell use among patients aged <60, 60-69, and ≥70 years were 7.8%, 5.7%, and 5.9%, respectively. There was a trend toward higher rates of backup stem cell use for second ASCT in patients who were younger, had suboptimal disease control at time of first ASCT, and longer PFS. The median dose of stem cell boost given was 5.6 × 106 CD34+ cells/kg (range, 1.9-20). The median time from stem cell boost to neutrophil, hemoglobin, and platelet engraftment was 4 (range, 2-11), 15 (range, 4-34), and 12 (range, 0-34) days, respectively. Lower CD34+ dose and older age at time of ASCT predicted need for stem cell boost. With new salvage therapies for relapsed MM, the rates of second ASCT are very low. The low rates of use suggest that institutional policies regarding universal BSC collection and long-term storage should be reassessed and individualized. However, need for stem cell boost in 2.3% of patients may present a challenge to that.

Long-term survival comparison between primary transplant and upfront curative treatment with salvage transplant for early stage hepatocellular carcinoma

BACKGROUND

Whether primary liver transplantation (PLT) or upfront curative treatment with salvage liver transplantation (SLT) is a better treatment option for early hepatocellular carcinoma (HCC) is controversial. This study aims to compare the long-term survival starting from the time of primary treatment between the two approaches for early HCC using propensity score matching (PSM) analysis.

METHODS

From 1995 to 2014, 175 patients with early HCC undergoing either PLT (n = 149) or SLT (n = 26) were retrospectively reviewed in a prospectively collected database. Patients' demographic data, tumor characteristics, short-term and long-term outcome were compared between two groups after PSM.

RESULTS

After matching, the baseline characteristics were comparable between mPLT group (n = 45) and mSLT group (n = 25). The tumor recurrence rate after transplant was significantly higher in mSLT group than mPLT group (28% vs. 15.6%). Calculating from the time of primary treatment, the 1, 3, and 5-year overall survival rates were comparable between mPLT group (97.8%, 91.1% and 86.3%) and mSLT group (100%, 95% and 85%). However, the 1, 3, and 5-year recurrence-free survival rates were significantly better in mPLT group than mSLT group (95.6% vs. 90%, 86.6% vs. 80% and 84.3% vs. 70%). SLT approach and high pre-treatment serum alpha-fetoprotein level (>200 ηg/mL) were poor prognostic factors for recurrence-free survival after transplant.

CONCLUSIONS

PLT may be a better treatment option for early HCC, whereas SLT approach for HCC should be cautiously considered under the circumstance of organ shortage.

Primary liver transplantation vs liver resection followed by transplantation for transplantable hepatocellular carcinoma: Liver functional quality and tumor characteristics matter

Liver resection (LR) and primary liver transplantation (LT) are two potentially curative treatment modalities for patients with hepatocellular carcinoma (HCC). If an underlying chronic liver disease exists, however, making a decision on which method should be selected is difficult. If a patient has no chronic liver disease, LR may be the preferable option with salvage transplantation (ST) in mind in case of recurrence. Presence of a moderate-to-severe liver failure accompanying HCC usually warrants primary LT. The treatment of patients with HCC and early-stage chronic liver disease remains controversial. The advantages of “LR-followed-by-ST-if-needed” strategy include less complicated index operation, no need for immunosuppression, use of donor livers for other patients in today’s organ shortage setting and comparable survival rates. However, primary LT has its own advantages as it also treats underlying chronic liver disease with carcinogenic potential, removes undetected tumor nodules and potentially eliminates need for a ST. An article recently published by Fuks et al in Hepatology offers an approach by which selecting between LR-followed-by-ST and immediate LT might be easier. Here we discuss the results of the aforementioned report in the light of currently available knowledge.