Peripheral Blood CD34 Donor Chimerism has Greater Clinical Utility Than CD3 for Detecting Relapse after Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia or Myelodysplastic Syndrome

Monitoring of donor chimerism (DC) may detect early relapse following allogeneic hematopoietic stem cell transplantation (allo-SCT) for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Most centers use unfractionated peripheral blood or T cells to monitor DC, although CD34⁺ DC may be more predictive. The limited adoption of CD34⁺ DC may be due to the lack of detailed, comparative studies. To address this knowledge gap, we compared peripheral blood CD34⁺ and CD3⁺ DC in 134 patients who underwent allo-SCT for AML or MDS. In July 2011, the Alfred Hospital Bone Marrow Transplantation Service adopted routine monitoring of DC in the lineage-specific CD34⁺ and CD3⁺ cell subsets from peripheral blood at 1, 2, 3, 4, 6, 9, and 12 months post-transplantation for AML or MDS. Immunologic interventions, including rapid withdrawal of immunosuppression, azacytidine, and donor lymphocyte infusion, were prespecified for CD34⁺ DC ≤80%. Overall, CD34⁺ DC ≤80% detected 32 of 40 relapses (positive predictive value [PPV], 68%; negative predictive value [NPV], 91%), compared with 13 of 40 relapses for CD3⁺ DC ≤80% (PPV, 52%; NPV, 75%). Receiver operating characteristic analysis showed the superiority of CD34⁺ DC, with the greatest value at day 120 post-transplantation. CD3⁺ DC provided additional value in only 3 cases, preceding CD34⁺ DC ≤80% by 1 month. We further show that the CD34⁺ DC sample can be used to detect NPM1^mut, with the combination of CD34⁺ DC ≤80% and NPM1^mut identifying the highest risk of relapse. Among the 24 patients in morphologic remission at the time of CD34⁺ DC ≤80%, 13 (54%) responded to immunologic interventions (rapid withdrawal of immunosuppression, azacitidine, or donor lymphocyte infusion) with recovery of CD34⁺ DC >80%, and 11 of these patients remained in complete remission for a median of 34 months (range, 28 to 97 months). In contrast, the other 9 patients did not respond to the clinical intervention and relapsed within a median of 59 days after detecting CD34⁺ DC ≤80%. The CD34⁺ DC was significantly higher in responders than in nonresponders (median, 72% versus 56%; P = .015, Mann-Whitney U test). Overall, monitoring of CD34⁺ DC was considered clinically useful (with early diagnosis of relapse enabling preemptive therapy or predicting low risk of relapse) in 107 of 125 evaluable patients (86%). Our findings show that peripheral blood CD34⁺ DC is feasible and superior to CD3⁺ DC for predicting relapse. It also provides a source of DNA for measurable residual disease testing, which may further stratify the risk of relapse. If validated by an independent cohort, our results suggest that CD34⁺ should be used in preference to CD3⁺ DC for detecting early relapse and guiding immunologic interventions following allo-SCT for AML or MDS.

Predictors and Outcomes of Dose Reduction of Methotrexate and Cyclosporin Graft-Versus-Host-Disease Prophylaxis Following Allogeneic Haematopoietic Cell Transplantation

BACKGROUND

Concern regarding dose-related toxicities of methotrexate (MTX) and cyclosporin (CYA) GVHD prophylaxis occasionally lead to dose alterations post allogeneic haematopoietic cell transplant (alloHCT).

AIM

To clarify causes of MTX and CYA dose alteration and assess impact on patient outcomes including GVHD, relapse, non-relapse mortality (NRM), and overall survival (OS).

METHOD

Analysis of retrospective data was performed in a single tertiary centre of patients who underwent alloHCT for any indication and who received GVHD prophylaxis with CYA and MTX between the years 2011 and 2015. Univariate analysis was conducted using the log-rank test for OS and using competing risk regression for NRM, relapse and GVHD. Fisher exact tests were used to determine if an association existed between each of the pre-transplant variables and MTX alteration. Multivariate models for OS and NRM were constructed using Cox proportional hazards modelling and competing risk regression respectively.

RESULTS

54/196 (28%) had MTX alterations and 61/187 (33%) had CYA alterations. Reasons for MTX alteration included mucositis, renal or liver impairment, fluid overload and sepsis. Causes of CYA alteration were numerous but most commonly due to acute kidney impairment. MTX alteration was associated with inferior OS (HR 2.4, P=<0.001) and higher NRM (OR 4.6, P<0.001) at 6 years(y) post-landmark. CYA alteration was associated with greater NRM (OR 2.7, P= 0.0137) at 6y. GVHD rates were unaffected by dose alteration.

CONCLUSIONS

Our findings suggest dose alteration in MTX and CYA GVHD prophylaxis is associated with adverse survival outcomes in alloHCT, without a significant impact on GVHD rates. This article is protected by copyright. All rights reserved.

Evaluation of EuroFlow minimal residual disease measurement and donor chimerism monitoring following tandem auto-allogeneic transplantation for multiple myeloma

Prognostic factors for multiple myeloma (MM) after allogeneic haemopoietic stem cell transplantation (alloHSCT) are poorly characterised. Two potential factors include minimal residual disease (MRD) and CD3⁺ donor-specific chimerism. We retrospectively examined 93 consecutive patients who received upfront or deferred tandem auto-alloHSCT. Bone marrow (Euroflow) MRD was assessed pre-alloHSCT and 3-monthly post-alloHSCT. CD3⁺ donor chimerism was assessed at D30, D60, D90, 6 m and 12 m post-alloHSCT. There was no statistical difference between upfront and deferred transplants in progression free survival (PFS) (34 m vs. 15 m respectively, p = 0.20) and overall survival (OS) (75.5 m vs. 62.7 m respectively, p = 0.56). Patients who were MRD-positive post-alloHSCT had inferior PFS to MRD-negative patients from 6 m (6 m HR 3.32, p = 0.02; 9 m HR 4.08, p = 0.003; 12 m HR 4.47, p = 0.008). Attainment or maintenance of MRD-negativity predicted reduced relapse risk (23.5% vs. 62.5%, p = 0.04). However, there was no significant difference in OS between the MRD-negative and positive groups. Full CD3⁺ donor chimerism at early time points (D30 and D90) was associated with increased risk of acute GVHD (D30 p < 0.001, D90 p = 0.006) and extensive chronic GVHD (D90 p = 0.04), but not PFS or OS. These data support the use of sequential MRD evaluation post-alloHSCT to inform intervention to eradicate persistent or emergent MRD-positive disease.