Safety and efficacy of plerixafor dose escalation for the mobilization of CD34+ hematopoietic progenitor cells in patients with sickle cell disease: interim results.

Gene therapy for sickle cell disease is limited by the yield of hematopoietic progenitor cells that can be harvested for transduction or gene editing. We therefore performed a phase I dose-escalation study of the hematopoietic progenitor cell mobilizing agent plerixafor to evaluate the efficacy and safety of standard dosing on peripheral blood CD34+ cell mobilization. Of 15 patients enrolled to date, only one was chronically transfused and ten were on hydroxyurea. Of eight patients who achieved a CD34+ cell concentration >30 cells/µL, six were on hydroxyurea. There was no clear dose response to increasing plerixafor dosage. There was a low rate of serious adverse events; two patients developed vaso-occlusive crises, at the doses of 80 µg/kg and 240 µg/kg. Hydroxyurea may have contributed to the limited CD34+ mobilization by affecting baseline peripheral blood CD34 counts, which correlated strongly with peak peripheral blood CD34 counts. Plerixafor administration did not induce significant increases in the fraction of activated neutrophils, monocytes, or platelets. However, increased neutrophils positive for activated ß2 integrin and Mac-1 were associated with serious adverse events. In summary, plerixafor was well tolerated but did not achieve consistent CD34+ cell mobilization in this cohort of patients, most of whom were being actively treated with hydroxyurea and only one was chronically transfused. The study will continue with escalation of the dose of plerixafor and modification of hydroxyurea administration. Clinicaltrials.gov identifier: NCT02193191.

Validating and implementing the use of an infusion pump for the administration of thawed hematopoietic progenitor cells-a single-institution experience.

BACKGROUND: Direct thaw and administration of previously cryopreserved peripheral blood stem cell products is a commonly used practice and should be performed rapidly to reduce cellular damage caused by dimethyl sulfoxide exposure. Cells are typically thawed at the bedside and infused by gravity through a high-flow-rate central venous catheter. An existing nontunneled catheter is occasionally used instead and often results in a slower infusion rate. To ensure expedient and consistent infusions, we validated and implemented the use of an infusion pump for thawed peripheral blood stem cells. STUDY DESIGN AND METHODS: Validation was performed in two phases: in vitro simulation and in vivo clinical assessment. Total nucleated cell recovery and viability plus progenitor cell viability and potency were compared in vitro between two cryopreserved peripheral blood stem cell units that were either passed through a preset infusion pump or drained by gravity. The infusion rate, adverse events, and engraftment times were retrospectively compared between patients who received infusions by infusion pump (n = 35) and by gravity (n = 38). RESULTS: No significant differences were observed in vitro between the infusion methods for all measured variables. Overall infusion rates were similar in vivo for both groups but were significantly lower for patients who had nontunneled catheters that delivered the infusion by gravity. The time to neutrophil and platelet engraftment was similar for both groups. CONCLUSION: This is the first study to assess the use of an infusion pump for stem cell transplant. The use of an infusion pump for peripheral blood stem cell infusion is safe, provides a reliable and consistent infusion method, and can mitigate the effect of the type of venous access line used.

A Phase I Trial of High-Dose Lenalidomide and Melphalan as Conditioning for Autologous Stem Cell Transplantation in Relapsed or Refractory Multiple Myeloma.

Autologous stem cell transplantation (ASCT) conditioned with high-dose chemotherapy has long been established as the standard of care for eligible patients with newly diagnosed multiple myeloma. Despite recent therapeutic advances, high-dose melphalan (HDM) remains the chemotherapy regimen of choice in this setting. Lenalidomide (LEN) in combination with low-dose dexamethasone is recognized as a standard of care for patients with relapsed or refractory multiple myeloma (RRMM), and there is growing support for the administration of LEN as maintenance therapy post-ASCT. In view of the above, the present phase I clinical trial was designed to evaluate the safety and tolerability of high-dose LEN (HDLEN) in patients with RRMM, and to determine the maximum tolerated dose of HDLEN when added to HDM before ASCT. Despite administering HDLEN at doses of up to 350 mg/day, the maximum tolerated dose could not be determined, owing to an insufficient number of dose-limiting toxicities in the 21 patients enrolled in the trial. Conditioning with HDLEN plus HDM was associated with a favorable tolerability profile. Adverse events following ASCT were as expected with HDM. Median progression-free and overall survival were 10 months and 22 months, respectively, in this population of heavily pretreated patients. Our findings suggest that HDLEN in combination with HDM may offer significant potential as a conditioning regimen before ASCT in patients with RRMM. These preliminary findings are now being evaluated further in an ongoing phase II clinical trial.

Sequential intensive chemotherapy followed by autologous or allogeneic transplantation for refractory lymphoma.

We evaluate the safety of bendamustine as a bridge to stem cell transplantation (SCT) in patients with relapsed/refractory lymphoma and residual disease after salvage therapy. Thirty-four subjects without complete responses (CR) received bendamustine 200 mg/m2/day for 2 days followed 14 days later by SCT. Sixteen subjects in partial remission (PR) with maximal FDG-PET SUVs ≤8 prior to bendamustine received autologous SCT, while 13 with suboptimal responses were allografted. Five subjects did not proceed to transplant. No bendamustine toxicities precluded transplantation and no detrimental effect on engraftment or early treatment-related mortality (TRM) was attributable to bendamustine. At 1 year, 75% of auto-recipients and 31% of allo-recipients were alive with CR. Two subjects in the autologous arm developed therapy-related myeloid neoplasia (t-MN). In conclusion, a bendamustine bridge to SCT can be administered without early toxicity to patients with suboptimal responses to salvage chemotherapy. However this approach may increase the risk of t-MN. (NCT02059239).Supplemental data for this article is available online at here.

Cord blood transplants supported by unrelated donor CD34+ progenitor cells.

Alternative donor transplantation with the haplo-cord platform allows the use of a lower-dose single umbilical cord blood unit (CBU) by co-infusion of third-party CD34+-selected cells from a haploidentical relative, which provides early transient engraftment while awaiting durable CBU engraftment. In our experience, ~15% of patients lack a suitable haploidentical donor. Here we report 26 patients who underwent haplo-cord transplant using CD34+-selected partially matched unrelated donor grafts. Twenty-four were conditioned with fludarabine/melphalan +/- low-dose TBI (n = 16). Twenty-five received ATG and all received posttransplant tacrolimus and mycophenolate mofetil. Median time to neutrophil and platelet recovery was 11 and 18 days. CBU engraftment, with CD33 and CD3 >5% cord chimerism in the myeloid/lymphoid compartment by day +60, occurred in 20 of 24 patients (83%). Incidence of grade 2-4 acute graft-versus-host disease (GVHD) was 27% at day +100, and chronic GVHD was 4% at 1 year. Overall survival at 1 year was 54%. For patients in need of an alternative transplant who lack a haploidentical donor, haplo-cord transplantation using CD34+-selected partially matched unrelated donor grafts results in rapid engraftment with no increased rate of cord graft failure or GVHD.

Adoptive immunotherapy with CB following chemotherapy for patients with refractory myeloid malignancy: chimerism and response.

We conducted a prospective evaluation of cord blood (CB)-derived adoptive cell therapy, after salvage chemotherapy, for patients with advanced myeloid malignancies and poor prognosis. Previously, we reported safety, feasibility, and preliminary efficacy of this approach. We present updated results in 31 patients who received intensive chemotherapy followed by CB infusion and identify predictors of response. To enhance the antileukemic effect, we selected CB units (CBU) with shared inherited paternal antigens and/or noninherited maternal antigens with the recipients. Twenty-eight patients with acute myeloid leukemia (AML), 2 with myelodysplastic syndrome, and 1 in chronic myeloid leukemia myeloid blast crisis were enrolled; 9 had relapsed after allogeneic transplant. Response was defined as <5% blasts in hypocellular bone marrow at 2 weeks after treatment. Thirteen patients (42%) responded; a rate higher than historical data with chemotherapy only. Twelve had CBU-derived chimerism detected; chimerism was a powerful predictor of response (P < .001). CBU lymphocyte content and a prior transplant were associated with chimerism (P < .01). Safety was acceptable: 3 patients developed mild cytokine release syndrome, 2 had grade 1 and 2 had grade 4 graft-versus-host disease. Seven responders and 6 nonresponders (after additional therapy) received subsequent transplant; 5 are alive (follow-up, 5-47 months). The most common cause of death for nonresponders was disease progression, whereas for responders it was infection. CB-derived adoptive cell therapy is feasible and efficacious for refractory AML. Banked CBU are readily available for treatment. Response depends on chimerism, highlighting the graft-versus-leukemia effect of CB cell therapy. This trial was registered at www.clinicaltrials.gov as #NCT02508324.

Prophylactic rituximab prevents EBV PTLD in haplo-cord transplant recipients at high risk.

Epstein-Barr virus (EBV) reactivation and post-transplant lymphoproliferative disorders (PTLD) are common and potentially fatal complications after allogeneic transplantation with mismatched donors and T-cell depletion. Haplo-cord transplantation combines a mismatched UCB graft with third-party cells. Conditioning involves thymoglobulin. EBV reactivation and PTLD were common in initial patients. As of March 2017, we administered a prophylactic dose of rituximab 375 mg/m2 pre-transplant. Among 147 patients who did not receive rituximab, the cumulative incidence of post-transplant EBV reactivation and of EBV PTLD was 13% and 8%, respectively. Among 51 who received pre-transplant rituximab, the incidences were 2% (p = .0017) and 0% (p = .04), respectively. There was no difference in time to hematopoietic recovery, in the incidence of CMV reactivation, of invasive blood stream infections or of proven or probable invasive fungal infections. Pre-transplant administration of rituximab is an effective and nontoxic intervention that drastically reduces EBV reactivation and PTLD in high-risk patients.

Haploidentical vs haplo-cord transplant in adults under 60 years receiving fludarabine and melphalan conditioning.

Haplo-identical transplant with posttransplant cyclophosphamide (haplo) and umbilical cord blood transplant supported by third-party CD34 cells (haplo-cord) are competing approaches to alternative donor transplant. We compared, in adults younger than age 60 years, the outcomes of 170 haplo at 1 institution with that of 137 haplo-cord at 2 other institutions. All received reduced intensity conditioning with fludarabine and melphalan ± total body irradiation. GVHD prophylaxis for haplo consisted of cyclophosphamide, tacrolimus, and mycophenolate, whereas haplo-cord received antithymocyte globulin, tacrolimus, and mycophenolate. Haplo transplant used mostly bone marrow, and peripheral blood stem cells were used in haplo-cord transplants. Haplo-cord were older and had more advanced disease. Haplo-cord hastened median time to neutrophil (11 vs 18 days, P = .001) and platelet recovery (22 vs 25 days, P = .03). At 4 years, overall survival (OS) was 50% for haplo-cord vs 49% for haplo. Progression-free survival (PFS) was 40% for haplo-cord vs 45% for haplo. In multivariate analysis, the disease risk index was significant for OS (hazard ratio, 1.8; 95% confidence interval, 1.48-2.17; P = .00) and PFS. Total body irradiation was associated with decreased recurrence and improved PFS, age >40 with increased nonrelapse mortality. The type of transplant had no effect on OS, PFS, relapse, or nonrelapse mortality. Cumulative incidence of grade 2-4 acute graft-versus-host disease (GVHD) by day 100 was 16% after haplo-cord vs 33% after haplo (P < .0001), but grade 3-4 GVHD was similar. Chronic GVHD at 1 year was 4% after haplo-cord vs 16% after haplo (P < .0001). Haplo or haplo-cord results in similar and encouraging outcomes. Haplo-cord is associated with more rapid neutrophil and platelet recovery and lower acute and chronic GVHD. Institutional review board authorization for this retrospective study was obtained at each institution. Some patients participated in trials registered at www.clinicaltrials.gov as #NCT01810588 and NCT01050946.

High-dose bendamustine and melphalan conditioning for autologous stem cell transplantation for patients with multiple myeloma.

High-dose melphalan (MEL200) followed by autologous stem cell transplantation (ASCT) remains a standard of care for multiple myeloma (MM). Bendamustine induces responses in MM resistant to other alkylators. Our prior Phase I trial adding bendamustine to MEL200 transplant conditioning resulted in no additional toxicity. We now report a single-arm, phase II study that evaluated the efficacy of bendamustine 225 mg/m2 with MEL200 conditioning for ASCT in 18 patients with newly diagnosed MM (NDMM) and 17 with relapsed or refractory MM (RRMM). The primary end point was the complete response (CR/sCR) rate at day+ 100. Sample size was determined according to Simon's two-stage design. At stage 1, sixteen patients entered the study. As there were eight patients with CR/sCR, enrollment increased to 28 patients. Sixteen out of the first 28 evaluable patients achieved CR/sCR, meeting the design criteria. Enrollment was then expanded to a total of 35 patients. 51% achieved a CR/sCR. After a median follow-up of 65 months, 21 patients progressed, including 7 deaths. The median PFS for NDMM and RRMM was 48 and 45 months, respectively. Bendamustine/MEL200 conditioning resulted in excellent overall and depth of response as well as PFS, particularly in the RRMM patients, and is worthy of further investigation (NCT00916058).