Christoph Faul

Phase II Trial of the Anti-CD19 Bispecific T Cell–Engager Blinatumomab Shows Hematologic and Molecular Remissions in Patients With Relapsed or Refractory B-Precursor Acute Lymphoblastic Leukemia

PURPOSE Patients with relapsed or refractory acute lymphoblastic leukemia (ALL) have a dismal prognosis. CD19 is homogenously expressed in B-precursor ALL and can be targeted by the investigational bispecific T cell-engager antibody blinatumomab. A phase II trial was performed to determine clinical activity in this patient cohort. PATIENTS AND METHODS Thirty-six patients with relapsed or refractory B-precursor ALL were treated with blinatumomab in cycles of 4-week continuous infusion followed by a 2-week treatment-free interval in a single-arm study with a dose-finding stage and an extension stage. The primary end point was complete remission (CR) or CR with partial hematologic recovery (CRh). Major secondary end points included minimal residual disease (MRD) response, rate of allogeneic hematopoietic stem-cell transplantation (HSCT) realization, relapse-free survival (RFS), overall survival (OS), and incidence of adverse events (AEs). RESULTS Median age was 32 years (range, 18 to 77 years). Twenty-five patients (69%) achieved a CR or CRh, with 88% of the responders achieving an MRD response. Median OS was 9.8 months (95% CI, 8.5 to 14.9), and median RFS was 7.6 months (95% CI, 4.5 to 9.5). Thirteen responders (52%) underwent HSCT after achieving a CR or CRh. The most frequent AE during treatment was pyrexia (grade 1 or 2, 75%; grade 3, 6%). In six patients with nervous system or psychiatric disorder AEs and in two patients with cytokine release syndrome, treatment had to be interrupted or discontinued. These medical events were resolved clinically. CONCLUSION The data support further investigation of blinatumomab for the treatment of adult patients with relapsed or refractory ALL in a larger confirmatory study.

Follow‐up of patients with progressive multiple myeloma undergoing allografts after reduced‐intensity conditioning

Summary. Allogeneic stem cell transplantation (allo‐SCT) after reduced‐intensity conditioning was evaluated in 22 patients (median age 53, range 36–66 years) with multiple myeloma with progression after an autologous SCT. Seven patients received a transplant from a human leucocyte antigen (HLA)‐identical sibling and 15 patients (68%) from an unrelated donor [including 3/22 (14%) from a HLA‐mismatched unrelated donor]. Graft‐versus‐host disease (GVHD) prophylaxis consisted of serotherapy with antithymocyte globulin (ATG) and cyclosporine (CSA) (n = 12) or CSA plus mycophenolate mofetil (n = 10). Despite of heavy pretreatment, the transplant‐related mortality (TRM) for all grafted patients was acceptable at 5/22 patients (23%). Seven of 21 patients (33%) that were evaluated developed grade II GVHD and one (5%) patient developed grade III/IV acute GVHD. Seven patients developed chronic GVHD (cGVHD), but only one was extensive. Eleven patients died of progressive disease within a median of 7 months (2–19 months) post transplant. Thirteen of all 22 patients (59%) achieved a partial or complete remission with six of these 13 patients (46%) remaining event free at a median of 24 months (range 8–36 months) post allografting. Estimated 2 year overall and event‐free survival was, respectively, 25·5% and 22·0% for the whole patient group, and 62·5% and 57·1% for patients with chemosensitive disease. Chemorefractory disease prior to allogeneic stem cell transplantation (P = 0·0182) and absence of cGVHD (P = 0·069) were associated with shorter event‐free survival. Thus long‐term disease control can be achieved, but is restricted to patients responding to prior salvage chemotherapy.

Randomized comparison of prophylactic and minimal residual disease-triggered imatinib after allogeneic stem cell transplantation for BCR-ABL1-positive acute lymphoblastic leukemia

Minimal residual disease (MRD) after allogeneic stem cell transplantation (SCT) for Ph+ acute lymphoblastic leukemia (ALL) is predictive of relapse. Imatinib administration subsequent to SCT may prevent relapse, but the role of scheduling and its impact on outcome are not known. In a prospective, randomized multicenter trial, we compared the tolerability and efficacy of post-transplant imatinib administered either prophylactically (arm A; n=26) or following detection of MRD (arm B; n=29). Prophylactic imatinib significantly reduced the incidence of molecular recurrence after SCT compared with MRD-triggered imatinib (40% vs 69%; P=0.046). Median duration of PCR negativity was 26.5 and 6.8 months, respectively (P=0.065). Five-year survival in both interventional groups was high (80 and 74.5%), despite premature discontinuation of imatinib in the majority of patients because of poor tolerability. Relapse probability was significantly higher in patients who became MRD positive (P=0.017). In conclusion, post-transplant imatinib results in a low relapse rate, durable remissions and excellent long-term outcome in patients with BCR–ABL1-positive ALL irrespective of whether it is given prophylactically or MRD-triggered. Reappearance of BCR–ABL1 transcripts early after SCT or at higher levels identifies a small subset of patients who do not benefit sufficiently from imatinib, and in whom alternative approaches should be explored.

Radioimmunotherapy with yttrium-90-ibritumomab tiuxetan as part of a reduced- intensity conditioning regimen for allogeneic hematopoietic cell transplantation in patients with advanced non-Hodgkin lymphoma: results of a phase 2 study

Forty patients were enrolled in this phase 2 study combining radioimmunotherapy (RIT) using yttrium-90-ibritumomab-tiuxetan (15 MBq [0.4 mCi]/kg) with reduced-intensity conditioning (RIC) using fludarabine (90 mg/m(2)) and 2 Gy total body irradiation followed by allogeneic hematopoietic cell transplantation (HCT) from related (n = 13) or unrelated (n = 27) donors for the treatment of advanced non-Hodgkin lymphoma. Diagnoses were follicular lymphoma (n = 17), chronic lymphocytic leukemia (n = 13), mantle cell lymphoma (n = 8), marginal zone lymphoma (n = 1), and lymphoplasmacytic lymphoma (n = 1). Median age was 55 years (range, 34-68 years). All patients were high risk with refractory disease or relapse after preceding autologous HCT. No additional toxicities attributable to RIT were observed. Engraftment was rapid and sustained. Incidences of acute graft-versus-host disease 2-4 and chronic graft-versus-host disease were 43% and 53%, respectively. Kaplan-Meier-estimated nonrelapse mortality was 45% at 2 years. Twenty-two of 40 patients (55%) are alive, resulting in a Kaplan-Meier-estimated 2-year survival of 51% for all, 67% for follicular lymphoma, 49% for chronic lymphocytic leukemia, and 37% for mantle cell lymphoma patients. The combined use of RIT with RIC is feasible with acceptable toxicity, even in elderly and heavily pretreated patients. This study is registered at www.clinicaltrials.gov as #NCT00302757.

Haploidentical allogeneic hematopoietic cell transplantation in adults using CD3/CD19 depletion and reduced intensity conditioning: a phase II study

Background We report a prospective multicenter phase II study of haploidentical hematopoietic stem cell transplantation using CD3/CD19-depleted grafts after reduced intensity conditioning with fludarabine, thiotepa, melphalan and OKT-3. Design and Methods Sixty-one adults with a median age of 46 years (range 19-65 years) have been enrolled. Diagnoses were acute myeloid leukemia (n=38), acute lymphoblastic leukemia (n=8), non-Hodgkins lymphoma (n=6), myeloma (n=4), chronic myeloid leukemia (n=3), chronic lymphatic leukemia (n=1) and myelodysplastic syndrome (n=1). Patients were considered high risk because of refractory disease (n=18), cytogenetics (n=6), complete remission (≥2) (n=9), chemosensitive relapse in partial remission (n=4) or relapse after prior hematopoietic stem cell transplantation (n=15 allogeneic, n=8 autologous, n=1 both). At haploidentical hematopoietic stem cell transplantation, 30 patients were in complete remission and 31 in partial remission. Grafts contained a median of 7.0×106 (range 3.2-22) CD34+ cells/kg, 4.2×104 (range 0.6-44) CD3+ T cells/kg and 2.7×107 (range 0.00-37.3) CD56+ cells/kg. Results Engraftment was rapid with a median of 12 days to granulocytes more than 0.5×109/L (range 9-50 days) and 11 days to platelets more than 20×109 (range 7-38 days). Incidence of grade IIIV acute graft-versus-host-disease and chronic graft-versus-host-disease was 46% and 18%, respectively. Non-relapse mortality on Day 100 was 23% and 42% at two years. Cumulative incidence of relapse/progression at two years was 31%. Kaplan-Meier estimated 1-year and 2-year overall survival with median follow up of 869 days (range 181-1932) is 41% and 28%, respectively. Conclusions This regimen allows successful haploidentical hematopoietic stem cell transplantation with reduced intensity conditioning in high-risk patients lacking a suitable donor. (clinicaltrials.gov identifier:NCT00202917).

Phenotypic and functional heterogeneity of human bone marrow- and amnion-derived MSC subsets

Bone marrow–derived mesenchymal stromal/stem cells (MSCs) are nonhematopoietic cells that are able to differentiate into osteoblasts, adipocytes, and chondrocytes. In addition, they are known to participate in niche formation for hematopoietic stem cells and to display immunomodulatory properties. Conventionally, these cells are functionally isolated from tissue based on their capacity to adhere to the surface of culture flasks. This isolation procedure is hampered by the unpredictable influence of secreted molecules, the interactions between cocultured hematopoietic and other unrelated cells, and by the arbitrarily selected removal time of nonadherent cells before the expansion of MSCs. Finally, functionally isolated cells do not provide biological information about the starting population. To circumvent these limitations, several strategies have been developed to facilitate the prospective isolation of MSCs based on the selective expression, or absence, of surface markers. In this report, we summarize the most frequently used markers and introduce new targets for antibody‐based isolation procedures of primary bone marrow‐ and amnion‐derived MSCs.

Ganciclovir-Resistant Cytomegalovirus Disease after Allogeneic Stem Cell Transplantation: Pitfalls of Phenotypic Diagnosis by In Vitro Selection of an UL97 Mutant Strain

A 9-month posttransplantation course of an allogeneic stem-cell transplant recipient (human cytomegalovirus [HCMV] serostatus, donor positive/recipient negative), in whom ganciclovir (GCV) resistance developed (UL97 mutations M460V, L595S, and C603W) on day 164 after transplantation and who developed HCMV retinitis and fatal HCMV encephalitis is presented. Virus strains isolated from secondary cultures were analyzed by UL97 restriction assays and sequencing and were compared with primary DNA extracts of the same specimens, which resulted in molecular proof of an initial HCMV strain-specific in vitro selection of the in vivo nondominant UL97 L595S-C603 mutant strain from 3 viral variants present in vivo. In addition, compartmentalization of virus present in blood and cerebrospinal fluid was found. The influence of rapidly increasing plasma virus load (to >10(6) copies/mL) and oral administration of GCV on the emergence of GCV resistance is shown. These findings have strong implications for the diagnosis of HCMV drug resistance.

Long-term survival and T-cell kinetics in relapsed/refractory ALL patients who achieved MRD response after blinatumomab treatment

This long-term follow-up analysis evaluated overall survival (OS) and relapse-free survival (RFS) in a phase 2 study of the bispecific T-cell engager antibody construct blinatumomab in 36 adults with relapsed/refractory B-precursor acute lymphoblastic leukemia (ALL). In the primary analysis, 25 (69%) patients with relapsed/refractory ALL achieved complete remission with full (CR) or partial (CRh) hematologic recovery of peripheral blood counts within the first 2 cycles. Twenty-five patients (69%) had a minimal residual disease (MRD) response (<10(-4) blasts), including 22 CR/CRh responders, 2 patients with hypocellular bone marrow, and 1 patient with normocellular bone marrow but low peripheral counts. Ten of the 36 patients (28%) were long-term survivors (OS ≥30 months). Median OS was 13.0 months (median follow-up, 32.6 months). MRD response was associated with significantly longer OS (Mantel-Byar P = .009). All 10 long-term survivors had an MRD response. Median RFS was 8.8 months (median follow-up, 28.9 months). A plateau for RFS was reached after ∼18 months. Six of the 10 long-term survivors remained relapse-free, including 4 who received allogeneic stem cell transplantation (allo-SCT) as consolidation for blinatumomab and 2 who received 3 additional cycles of blinatumomab instead of allo-SCT. Three long-term survivors had neurologic events or cytokine release syndrome, resulting in temporary blinatumomab discontinuation; all restarted blinatumomab successfully. Long-term survivors had more pronounced T-cell expansion than patients with OS <30 months.

Immune reconstitution after haploidentical hematopoietic cell transplantation: impact of reduced intensity conditioning and CD3/CD19 depleted grafts

Haploidentical hematopoietic cell transplantation (HHCT) using CD34 selected grafts is complicated by slow engraftment and immune reconstitution. Engraftment and immune reconstitution might be improved using CD3/CD19-depleted grafts and reduced intensity conditioning (RIC). We report on 28 patients after HHCT with CD3/CD19-depleted grafts using RIC, which were prospectively evaluated for engraftment and immune reconstitution. Engraftment was rapid with full chimerism reached on day +15 after HHCT. T-cell reconstitution was delayed with a median of 205 CD3+ cells/μl, 70 CD3+CD4+ cells/μl and 66 CD3+ CD8+ cells/μl on day +100, respectively. A skewed T-cell receptor-Vβ repertoire with oligoclonal T-cell expansions to day +100 and normalization after day +200 was observed. B-cell reconstitution was slow with a median of 100 CD19+ CD20+ cells/μl on day +150. Natural killer (NK) cell engraftment was fast reaching normal values on day +20. An increased natural cytotoxicity receptor and NKG2A, but decreased NKG2D and KIR expressions were observed on NK cells until day +100. We observed a positive impact of donor lymphocyte infusions on immune reconstitution. In conclusion, after HHCT, using CD3/CD19-depleted grafts and RIC, T- and B-cell reconstitution is delayed, whereas NK-cell reconstitution occurs early and fast.

Desensitization of platelets to iloprost. Loss of specific binding sites and heterologous desensitization of adenylate cyclase.

The binding characteristics of [3H]prostacyclin and [3H]iloprost ([3H]5-[(E)-(1S,5S,6R,7R)-7-hydroxy-6-[(E)-(3S,4RS) -3-hydroxy-4-methyl-1-octen-6-inyl]-bicyclo[3.3.0]octan-3-yl idene] -pentanoic acid) and platelet adenylate cyclase activities were investigated in platelet-rich plasma preincubated with iloprost. The exposure of platelets to 0.1 microM iloprost (12 h, 20 degrees C) caused a significant loss of iloprost binding sites (P less than 0.01) without causing changes in binding affinity. This loss of specific [3H]iloprost binding was time- and dose-dependent. The reduction of iloprost receptor density was accompanied by an impaired responsiveness of platelet adenylate cyclase to iloprost, prostaglandin D2 and forskolin. In contrast, basal adenylate cyclase activity was not affected by iloprost pretreatment. The diminished response of the enzyme to GTP and NaF pointed to an involvement of the stimulatory guanyl nucleotide-binding protein (Gs) in iloprost-induced heterologous desensitization. Consequently, [32P]NAD+ and cholera toxin were used for the direct labelling of Gs. Platelet membranes desensitized to iloprost incorporated less label into the 45 kD subunit of Gs. These data suggest that the site of action of iloprost for heterologous desensitization of human platelet adenylate cyclase is located on Gs.