Faculty Bibliography

Assessment of minimal residual disease (MRD) is being routinely used to assess response in patients with acute myeloid leukaemia (AML). While it is well established that pre-transplant positive MRD studies predict for relapse in patients transplanted either from matched sibling donors or matched unrelated donors, it is currently unknown whether MRD has comparable prognostic value in haploidentical stem cell transplantation (haplo-SCT). To this end we performed a retrospective analysis using the Acute Leukaemia Working Party/European Society of Blood and Marrow Transplantation multicentre registry. All adult AML patients with known MRD status at transplant who underwent a first T-cell replete haplo-SCT while in remission between 2006 and 2016 were included. Two hundred and sixty-five MRD-negative and 128 MRD-positive patients were assessed. In multivariate analysis, MRD-negative patients experienced lower relapse incidence and better leukaemia-free survival (LFS) compared to MRD-positive patients. Subset analysis for MRD-positive patients revealed that patients with donors positive for cytomegalovirus experienced decreased relapse rates as well as increased survival. A 6-month landmark analysis suggests that the clinical benefit of pre-transplant MRD negativity in terms of relapse, overall survival and LFS is realized at this time point. Pre-transplant MRD status is potentially a pivotal prognosticator of outcome in AML patients undergoing T-cell replete haplo-SCT.

Haplo-identical transplants (Haplo-Tx) are an important alternative for patients with hematological malignancies who lack a HLA-identical donor. Seventy-one T-replete Haplo-Tx were performed in 70 high-risk patients at our center; 22/70 (31%) patients with refractory/relapsed leukemia received sequential salvage therapy (SeqTh) with high-dose chemotherapy followed by Haplo-Tx during the chemotherapy-induced neutropenia. Graft-versus-host disease (GVHD) prophylaxis consisted of post-transplant cyclophosphamide (days + 3 and + 4) with tacrolimus and mycophenolic acid. After a median follow-up of 29.2 months, 3-year overall survival (OS) and event-free survival (EFS) were 43.8 and 40.2%, while 3-year cumulative incidences (CIs) of non-relapse mortality (NRM) and relapse (RI) were 27 and 33%. Day 100 and day 400 CI of grade III-IV acute and moderate-severe chronic GVHD were 11 and 15%. Three-year RI was significantly lower in patients in complete remission (CR) versus those not in CR at the time of transplant (21.5 vs. 48%, p = 0.009) and in patients who received PBSC as compared to BM (22 vs. 45%, p = 0.009). In patients treated with SeqTh, 3-year OS was 19%, while 3-year RI and NRM were 52 and 28% at a median follow-up of 50 months. Overall, Haplo-Tx was feasible in heavily pretreated high-risk patients without a suitable HLA-identical donor.

We evaluated the potential correlation of the hematopoietic cell transplantation comorbidity index (HCT-CI) with the risk of developing post-transplant invasive fungal infections (IFIs). Between January 2009 and March 2015, 312 consecutive patients who received a first allograft entered the study. Low/intermediate HCT-CI risk score (0-2) was observed in 172/312 (55%), whereas high HCT-CI score (≥3) was seen in 140/312 (45%). Overall, 51/312 (16%) patients experienced IFI, defined as possible in 19 (6%), probable in 27 (9%), and proven in 5 (2%). Cumulative incidence of probable-proven IFI at 1 year was 8.5% with a significant higher incidence in patients with high HCT-CI (12%) vs. those with low-intermediate HCT-CI (5%; p = 0.006). There was a strong trend for a higher incidence of baseline severe pulmonary comorbidity in patients who developed probable-proven IFI (p = 0.051). One-year cumulative incidence of non-relapse mortality was higher in patients with IFI vs. those without, 49 and 16% (p < 0.001). By multivariate analysis, disease status at transplant and high HCT-CI, when combined with acute GVHD, were independently associated with the risk of post-transplant IFI. This study shows that a high HCT-CI predicts the risk of developing IFI and may indicate the need of mold-active antifungal prophylaxis in high-risk patients.

Busulfan plus cyclophosphamide (BuCy) is the traditional conditioning regimen for allogeneic stem cell transplant (allo-SCT) for young, fit patients with acute myeloid leukemia (AML). The thiotepa-busulfan-fludarabine (TBF) protocol has recently demonstrated promising outcome in cord blood and haploidentical SCT; however, there is limited evidence about this regimen in transplant from matched siblings (MSD) and unrelated donors (UD). We retrospectively compared outcomes of 2523 patients aged 18-50 with AML in remission, undergoing transplant from MSD or UD prepared with either TBF or BuCy conditioning. A 1:3 pair-matched analysis was performed: 146 patients receiving TBF were compared with 438 patients receiving BuCy. Relapse risk was significantly lower in the TBF when compared with BuCy group (HR 0.6, P = .02), while NRM did not differ. No significant difference was observed in LFS and OS between the two regimens. TBF was associated with a trend towards higher risk of grades III-IV aGVHD (HR 1.8, P = .06) and inferior cGVHD (HR 0.7, P = .04) when compared with BuCy. In patients undergoing transplant in first remission, the advantage for TBF in terms of relapse was more evident (HR 0.4, P = .02), leading to a trend for better LFS in favor of TBF (HR 0.7, P = .10), while OS did not differ between the two cohorts. In conclusion, TBF represents a valid myeloablative conditioning regimen providing significantly lower relapse and similar survival when compared with BuCy. Patients in first remission appear to gain the most from this protocol, as in this subgroup a tendency for better LFS was observed when compared with BuCy.

The introduction of novel agents in the management of multiple myeloma and related plasma cell dyscrasias has changed our treatment approaches and subsequently the outcome of patients. Due to current advances, the European Myeloma Network updated the diagnostic and therapeutic recommendations for patients with Waldenström's macroglobulinemia (WM), AL-amyloidosis, monoclonal immunoglobulin deposition disease (MIDD), POEMS syndrome, and primary plasma cell leukemia. For patients with WM, the combination of rituximab with chemotherapy remains the treatment cornerstone, while the Bruton-tyrosine kinase inhibitor ibrutinib has been introduced and approved for relapsed/refractory disease. The management of light chain amyloidosis depends on the presence and severity of heart disfunction. If present, intensification with an autologous stem cell transplantation (ASCT) is not recommended. Further aggregation of misfolded light chains could be prevented by doxycycline or monoclonal antibodies targeting amyloid deposits. Initial treatment generally consists of melphalan/dexamethasone or bortezomib-based regimens. For relapsing patients, one can consider proteasome inhibitors, immunomodulatory agents, melphalan or daratumumab. Because intact or light-chain immunoglobulins are also the culprits for MIDD, the small monoclonal plasma cells' clones should be treated and generally respond well to bortezomib-based treatment. POEMS syndrome is a well-defined clinical entity that can present as solitary bone lesions or disseminated disease. Radiation therapy is used for patients with localized disease and result in long-lasting response. Systemic treatment should be proposed to patients with disseminated disease, but regimens that can worsen a pre-existing polyneuropathy should be avoided. PPCL is located at the other end of the spectrum of plasma cell disorders and is associated with an aggressive disease course and poor prognosis. It requires an imminent, multi-phase and novel agents-based therapy, including induction, ASCT, consolidation and maintenance, with short treatment-free intervals. Patients not eligible for transplant procedures require personalized, intensive therapeutic approach. Allogeneic stem cell transplantation can be used in selected patients.

Pure RBC aplasia (PRCS) is a well-recognized complication after allogeneic hematopoietic stem cell transplantation (HSCT). Many therapeutic options are available to treat this condition, including erythropoietin, rituximab, bortezomib, plasma exchange, immunoadsorption, donor lymphocyte infusion, mesenchymal stem cells, antithymocyte globulin, and high-dose steroids; however, treatment outcomes are often variable and can sometimes lead to disappointing results. In this brief article we report our experience with 2 patients with PRCA after major ABO-incompatible HSCT who were resistant to multiple therapeutic interventions and who eventually benefited from treatment with eltrombopag, a thrombopoietin mimetic approved by the US Food and Drug Administration for the treatment of patients with immune thrombocytopenic purpura or severe aplastic anemia refractory to immunosuppressive agents or not eligible for HSCT. Data from these 2 patients show that eltrombopag was effective in treating erythroid aplasia and transfusion dependence after HSCT in patients who did not benefit from multiple previous treatments. Moreover, eltrombopag was well tolerated, with only a transient thrombocytosis requiring dose adjustment and no evidence of clonal evolution. Based on the positive results obtained in these 2 patients, we suggest that eltrombopag may have a favorable effect on unilineage cytopenias such as PRCA. Further studies in a large proportion of patients are mandatory to confirm these preliminary results.