Page 163 - Haematologica3

Bortezomib-based RIC HSCT: Phase II RCT
(aGvHD) and non-relapse mortality (NRM), with worse progression-free survival (PFS) and overall survival (OS) for 7/8 vs. 8/8 HLA-matched donors.2
The proteasome-inhibitor bortezomib (bort) can selec-
tively deplete proliferating alloreactive T lymphocytes,
reduce Th1 cytokines and Interleukin-6 levels, and block
antigen-presenting cell (APC) activation.3-6 It can also spare
regulatory T cells (Tregs) that are relevant in GvHD con-
trol.7 Administered early after graft infusion, short-course
bort can control GvHD in major histocompatibility com-
plex (MHC)-mismatched mouse HSCT and maintain
graft-versus-tumor responses,6,8,9 while avoiding the pro-
inflammatory colonic toxicity of delayed or prolonged bort.5,8,10
In a phase I/II study of RIC we documented that bort- based GvHD prophylaxis (bort 1.3 mg/m2 IV on d +1, +4, +7, plus conventional tacrolimus [tax] and methotrexate [mtx]) was safe and potentially efficacious in T-replete HLA-mismatched donor (MMD) transplantation, with survival comparable to HLA-matched cohorts.11,12 These data were used to support the inclusion of the bort-based regimen as one novel arm of an ongoing multicenter phase II randomized trial, comparing it to two other novel regi- mens: post-transplant cyclophosphamide (PTCy), and maraviroc, each compared to a non-randomized ‘conven- tional care’ cohort (The Blood and Marrow Transplant Clinical Trials Network [BMTCTN] 1203).
We additionally conducted a phase II randomized con- trol trial (RCT) for patients lacking 8/8 HLA-matched sib- ling donors (DFCI 12-404), directly randomizing conven- tional tac/mtx vs. two novel bort-based GvHD prophylax- is regimens, whose mature results we report herein. The regimens comprised bort plus tac/mtx (arm B), directly based on our phase I/II data; and bort plus sirolimus (sir)/tac (arm C), to explore the tolerizing effects of enhanced Treg sparing with combined proteasome- and mechanistic target of rapamycin (mTOR)-inhibition dur- ing early immune reconstitution.7,13 We chose bort/sir/tac instead of bort-based calcineurin inhibitors (CNI)-free pro- phylaxis (e.g., bort/sir/mycophenolate mofetil [MMF]) as the sir/MMF doublet has limited clinical efficacy,14 and in our experience, adding bort to sir/MMF did not provide adequate efficacy in GvHD prevention, while the sir/tac doublet has documented efficacy comparable to conven- tional tac/mtx.15
Methods
This prospective clinical trial was approved by the institutional review board of the Dana-Farber Cancer Institute/Harvard Cancer Center. Written informed consent was obtained prior to patient enrollment.
Study Design
The study was a one-stage randomized phase II trial with the primary objective of comparing the incidence of aGvHD in two bort-based GvHD prophylaxis regimens to conventional tac/mtx. The study was designed for the primary comparisons of the grade II-IV aGvHD rates in Arm A vs. B and Arm A vs. C in parallel, and was powered to test the hypothesis of superiority in Arm B and C (15%), compared to that in Arm A (40%). The accrual goal was 138 patients, randomizing all eligible patients in 1:1:1 ratio to the three regimens. Randomization was stratified by degree of HLA- match (8/8 vs. 7/8).
Patients
Adult hematologic malignancy patients lacking an available HLA-matched sibling with an available 8/8 (HLA-A, -B, -C, - DRB1) matched unrelated donor (MUD) or 1-antigen/allele mis- matched related donor (MMRD) or mismatched unrelated donor (MMUD) were enrolled on the trial between January 2013 and November 2015. Patients with HIV infection, active hepatitis B or C disease, abnormal renal (serum creatinine > upper limit of nor- mal [ULN] with clearance <40 mL/min/1.73m2 body surface area [BSA]) or liver function (serum total bilirubin >ULN, serum ala- nine/aspartate aminotransferase >2x ULN), Eastern Cooperative Oncology Group (ECOG) performance status >2, hyperlipidemia (serum cholesterol >300mg/dL; trigylcerides >400mg/dL) despite therapy, and peripheral neuropathy ≥grade 2 within 21 days prior to transplantation were excluded.
Transplantation
Conditioning comprised busulfan (0.8 mg/kg twice daily IV) and fludarabine (30 mg/m2 once daily IV) from days -5 to -2. T- replete donor peripheral blood stem cells (PBSC) dosed at ≥ 2x106 CD34+ cells/kg were infused on day 0. GvHD prophylaxis regi- mens were: tac/mtx (arm A), bort/tac/mtx (arm B), and bort/sir/tac (arm C). Dosing was: bort (1.3 mg/m2 IV on day +1, +4, +7), mtx (10 mg/m2 IV on day +1, 5 mg/m2 on day +3, +6, +11), sir (target trough level 5-12 ng/ml) and/or tac (target trough level 5-10 ng/ml) from day -3. The tapering of immunosuppression started at around d+100, with the aim of being off immune suppression (IS) by day +180, as applicable per treatment arm.
Participants received levetiracetam for seizure prophylaxis from day -5 to -1 and filgrastim 5 μg/kg daily from day +1 until an absolute neutrophil count (ANC) >1500 cells/μl was attained, and at least 12 months of Pneumocystis jiroveci and herpes simplex virus (HSV)/ varicella zoster virus (VZV) prophylaxis. Anti-fungal pro- phylaxis was not routine.
Immunophenotyping
CD4+ T cells were defined as CD3+CD4+; CD8+ T cells were defined as CD3+CD8+; CD8+ naïve cells were defined as CD8+CD45RO-CD62L+; CD4 Tregs were defined as CD3+CD4+CD25med-highCD127low; CD4 conventional T cells (Tcons) were defined as CD3+CD4+CD25low-negCD127med-high; natural killer (NK) cells as CD56+CD3–; and B cells as CD19+. Aliquots of anti- coagulated whole blood (ethylenediaminetetraacetic acid [EDTA]) were incubated with fluorophore-conjugated monoclonal anti- bodies: anti-CD3 V450 (clone UCHT1, BD Biosciences), anti-CD4 APC-H7 (clone RPA-T4, BD Biosciences), anti-CD8 Pacific-Orange (clone RPA-T8, Biolegend), anti-CD25 PE-Cy7 (clone M-A251, BD Biosciences), anti-CD127 PE-Cy5 (clone eBioRDR5, eBioscience) for T-cell subsets; anti-CD56 PE (clone B159, BD Biosciences), anti-CD3 V450 (clone UCHT1, BD Biosciences) for NK/NKT cells, and anti-CD19 APC (clone HIB19, BD Biosciences) for B cells. RBC lysis with BD Pharm Lyse was performed either prior to or following incubation with conjugated antibodies. Flow cytometry analysis utilized FACSCanto II (BD Bioscience) or the Fortessa (BD Bioscience) and FACSDiva software (BD Bioscience). There was a change in the use of flow cytometry machines over the course of the study. Both flow cytometers were validated and results were comparable.
Statistical considerations
The primary endpoint was a grade II-IV aGvHD rate by day 180 after stem cell infusion. Secondary endpoints included cumulative incidence of aGvHD, NRM, relapse, chronic (c)GvHD, and PFS, OS and GvHD-free/relapse-free survival (GRFS). The study was designed for the primary comparisons of the grade II-IV aGvHD
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