Carol Ann Huff

HLA-Haploidentical Bone Marrow Transplantation for Hematologic Malignancies Using Nonmyeloablative Conditioning and High-Dose, Posttransplantation Cyclophosphamide

We evaluated the safety and efficacy of high-dose, posttransplantation cyclophosphamide (Cy) to prevent graft rejection and graft-versus-host disease (GVHD) after outpatient nonmyeloablative conditioning and T cell-replete bone marrow transplantation from partially HLA-mismatched (haploidentical) related donors. Patients with advanced hematologic malignancies (n = 67) or paroxysmal nocturnal hemoglobinuria (n = 1) received Cy 50 mg/kg i.v. on day 3 (n = 28) or on days 3 and 4 (n = 40) after transplantation. The median times to neutrophil (>500/microL) and platelet recovery (>20,000/microL) were 15 and 24 days, respectively. Graft failure occurred in 9 of 66 (13%) evaluable patients, and was fatal in 1. The cumulative incidences of grades II-IV and grades III-IV acute (aGVHD) by day 200 were 34% and 6%, respectively. There was a trend toward a lower risk of extensive chronic GVHD (cGVHD) among recipients of 2 versus 1 dose of posttransplantation Cy (P = .05), the only difference between these groups. The cumulative incidences of nonrelapse mortality (NRM) and relapse at 1 year were 15% and 51%, respectively. Actuarial overall survival (OS) and event-free survival (EFS) at 2 years after transplantation were 36% and 26%, respectively. Patients with lymphoid malignancies had an improved EFS compared to those with myelogenous malignancies (P = .02). Nonmyeloablative HLA-haploidentical BMT with posttransplantation Cy is associated with acceptable rates of fatal graft failure and severe aGVHD or cGVHD.

Clonogenic Multiple Myeloma Progenitors, Stem Cell Properties, and Drug Resistance

Many agents are active in multiple myeloma, but the majority of patients relapse. This clinical pattern suggests most cancer cells are eliminated, but cells with the clonogenic potential to mediate tumor regrowth are relatively chemoresistant. Our previous data suggested that CD138(+) multiple myeloma plasma cells cannot undergo long-term proliferation but rather arise from clonogenic CD138(neg) B cells. We compared the relative sensitivity of these distinct cell types to clinical antimyeloma agents and found that dexamethasone, lenadilomide, bortezomib, and 4-hydroxycyclophosphamide inhibited CD138(+) multiple myeloma plasma cells but had little effect on CD138(neg) precursors in vitro. We further characterized clonogenic multiple myeloma cells and stained cell lines using the Hoechst side population and Aldefluor assays. Each assay identified CD138(neg) cells suggesting that they possess high drug efflux capacity and intracellular drug detoxification activity. We also found that multiple myeloma cells expressing the memory B-cell markers CD20 and CD27 could give rise to clonogenic multiple myeloma growth in vitro and engraft immunodeficient nonobese diabetes/severe combined immunodeficient mice during both primary and secondary transplantation. Furthermore, both the side population and Aldefluor assays were capable of identifying circulating clonotypic memory B-cell populations within the peripheral blood of multiple myeloma patients. Our results suggest that circulating clonotypic B-cell populations represent multiple myeloma stem cells, and the relative drug resistance of these cells is mediated by processes that protect normal stem cells from toxic injury.

Hedgehog signaling maintains a tumor stem cell compartment in multiple myeloma

The cancer stem cell hypothesis suggests that malignant growth depends on a subset of tumor cells with stem cell-like properties of self-renewal. Because hedgehog (Hh) signaling regulates progenitor cell fate in normal development and homeostasis, aberrant pathway activation might be involved in the maintenance of such a population in cancer. Indeed, mutational activation of the Hh pathway is associated with medulloblastoma and basal cell carcinoma; pathway activity is also critical for growth of other tumors lacking such mutations, although the mechanism of pathway activation is poorly understood. Here we study the role and mechanism of Hh pathway activation in multiple myeloma (MM), a malignancy with a well defined stem cell compartment. In this model, rare malignant progenitors capable of clonal expansion resemble B cells, whereas the much larger tumor cell population manifests a differentiated plasma cell phenotype that pathologically defines the disease. We show that the subset of MM cells that manifests Hh pathway activity is markedly concentrated within the tumor stem cell compartment. The Hh ligand promotes expansion of MM stem cells without differentiation, whereas the Hh pathway blockade, while having little or no effect on malignant plasma cell growth, markedly inhibits clonal expansion accompanied by terminal differentiation of purified MM stem cells. These data reveal that Hh pathway activation is heterogeneous across the spectrum of MM tumor stem cells and their more differentiated progeny. The potential existence of similar relationships in other adult cancers may have important biologic and clinical implications for the study of aberrant Hh signaling.

High-dose cyclophosphamide as single-agent, short-course prophylaxis of graft-versus-host disease

Because of its potent immunosuppressive yet stem cell-sparing activity, high-dose cyclophosphamide was tested as sole prophylaxis of graft-versus-host disease (GVHD) after myeloablative allogeneic bone marrow transplantation (alloBMT). We treated 117 patients (median age, 50 years; range, 21-66 years) with advanced hematologic malignancies; 78 had human leukocyte antigen (HLA)-matched related donors and 39 had HLA-matched unrelated donors. All patients received conventional myeloablation with busulfan/cyclophosphamide (BuCy) and T cell-replete bone marrow followed by 50 mg/kg/d of cyclophosphamide on days 3 and 4 after transplantation. The incidences of acute grades II through IV and grades III through IV GVHD for all patients were 43% and 10%, respectively. The nonrelapse mortality at day 100 and 2 years after transplantation were 9% and 17%, respectively. The actuarial overall survival and event-free survivals at 2 years after transplantation were 55% and 39%, respectively, for all patients and 63% and 54%, respectively, for patients who underwent transplantation while in remission. With a median follow-up of 26.3 months among surviving patients, the cumulative incidence of chronic GVHD is 10%. These results suggest that high-dose posttransplantation cyclophosphamide is an effective single-agent prophylaxis of acute and chronic GVHD after BuCy conditioning and HLA-matched BMT (clinicaltrials.gov no. NCT00134017).

Nonmyeloablative HLA-Haploidentical Bone Marrow Transplantation with High-Dose Posttransplantation Cyclophosphamide: Effect of HLA Disparity on Outcome

Although some reports have found an association between increasing HLA disparity between donor and recipient and fewer relapses after allogeneic blood or marrow transplantation (BMT), this potential benefit has been offset by more graft-versus-host disease (GVHD) and nonrelapse mortality (NRM). However, the type of GVHD prophylaxis might influence the balance between GVHD toxicity and relapse. The present study analyzed the impact of greater HLA disparity on outcomes of a specific platform for nonmyeloablative (NMA), HLA-haploidentical transplantation. A retrospective analysis was performed of 185 patients with hematologic malignancies enrolled in 3 similar trials of NMA, related donor, haploidentical BMT incorporating high-dose posttransplantation cyclophosphamide for GVHD prophylaxis. No significant association was found between the number of HLA mismatches (HLA-A, -B, -Cw, and -DRB1 combined) and risk of acute grade II-IV GVHD (hazard ratio [HR] = 0.89; P = .68 for 3-4 vs fewer antigen mismatches). More mismatching also had no detrimental effect on event-free survival (on multivariate analysis, HR = 0.60, P = .03 for 3-4 vs fewer antigen mismatches and HR = 0.55, P = .03 for 3-4 vs fewer allele mismatches). Thus, greater HLA disparity does not appear to worsen overall outcome after NMA haploidentical BMT with high-dose posttransplantation cyclophosphamide.

Risk-stratified outcomes of nonmyeloablative HLA-haploidentical BMT with high-dose posttransplantation cyclophosphamide

Related HLA-haploidentical blood or marrow transplantation (BMT) with high-dose posttransplantation cyclophosphamide (PTCy) is being increasingly used because of its acceptable safety profile. To better define outcomes of nonmyeloablative (NMA) HLA-haploidentical BMT with PTCy, 372 consecutive adult hematologic malignancy patients who underwent this procedure were retrospectively studied. Risk-stratified outcomes were evaluated using the refined Disease Risk Index (DRI), developed to stratify disease risk across histologies and allogeneic BMT regimens. Patients received uniform conditioning, T-cell-replete allografting, then PTCy, mycophenolate mofetil, and tacrolimus. Six-month probabilities of nonrelapse mortality and severe acute graft-versus-host disease were 8% and 4%. With 4.1-year median follow-up, 3-year probabilities of relapse, progression-free survival (PFS), and overall survival (OS) were 46%, 40%, and 50%, respectively. By refined DRI group, low (n = 71), intermediate (n = 241), and high/very high (n = 60) risk groups had 3-year PFS estimates of 65%, 37%, and 22% (P < .0001), with corresponding 3-year OS estimates of 71%, 48%, and 35% (P = .0001). On multivariable analyses, the DRI was statistically significantly associated with relapse, PFS, and OS (each P < .001). This analysis demonstrates that the DRI effectively risk stratifies recipients of NMA HLA-haploidentical BMT with PTCy and also suggests that this transplantation platform yields similar survivals to those seen with HLA-matched BMT.

Epidemiology and Outcomes of Clostridium difficile Infections in Hematopoietic Stem Cell Transplant Recipients

Background. Clostridium difficile is the leading cause of infectious diarrhea among hospitalized patients and is a major concern for patients undergoing hematopoietic stem cell transplantation (HSCT). Risk factors and the natural history of C. difficile infection (CDI) are poorly understood in this population. Methods. We performed a retrospective nested case-control study to describe the epidemiology, timing, and risk factors for CDI among adult patients who received HSCTs at our center from January 2003 through December 2008. Results. The overall 1-year incidence of CDI was 9.2% among HSCTs performed (n = 999). The median time to diagnosis of CDI was short among both autologous and allogeneic HSCT recipients (6.5 days and 33 days, respectively). Risk factors for CDI in allogeneic HSCT recipients included receipt of chemotherapy prior to conditioning for HSCT, broad-spectrum antimicrobial use, and acute graft-versus-host disease (GVHD; adjusted odds ratio [AOR], 4.45; 95% confidence interval [CI], 1.54-12.84; P = .006). There was a strong relationship between early CDI and subsequent development of gastrointestinal tract GVHD in the year following allogeneic HSCT (P < .001). Gastrointestinal GVHD was also strongly associated with an increased risk for recurrent CDI (AOR, 4.23 [95% CI, 1.20-14.86]; P = .02). Conclusions. These results highlight the high incidence and early timing of CDI after HSCT. Early timing, coupled with the noted risk of pretransplant chemotherapy, suggests that the natural history of disease in some patients may involve colonization prior to HSCT. A potentially important interplay between CDI and GVHD involving the gastrointestinal tract was observed.

Outcomes of Nonmyeloablative HLA-Haploidentical Blood or Marrow Transplantation With High-Dose Post-Transplantation Cyclophosphamide in Older Adults

PURPOSE Recent advances in nonmyeloablative (NMA), related HLA-haploidentical blood or marrow transplantation (haplo-BMT) have expanded the donor pool. This study evaluated the effect of age on NMA haplo-BMT outcomes in patients age 50 to 75 years. PATIENTS AND METHODS A retrospective analysis was performed of 271 consecutive patients with hematologic malignancies, age 50 to 75 years, who received NMA, T-cell-replete haplo-BMT with high-dose post-transplantation cyclophosphamide. RESULTS The median age was 61 years, with 115 patients (42%) age 50 to 59, 129 (48%) age 60 to 69, and 27 (10%) age 70 to 75 years. Overall, 84% of patients had intermediate- or high-/very high-risk disease. The 6-month probabilities of grade 3 or 4 acute graft-versus-host disease (GVHD) and nonrelapse mortality (NRM) were 3% and 8%, respectively. Patients in their 50s, 60s, and 70s had 6-month NRM probabilities of 8%, 9%, and 7%, respectively (P=.20). With a median follow-up of 4 years, corresponding 3-year progression-free survival probabilities were 39%, 35%, and 33% (P=.65), and corresponding 3-year overall survival probabilities were 48%, 45%, and 44% (P=.66). Three-year progression-free survival probabilities were 40% in acute myeloid leukemia (n=65), 39% in aggressive non-Hodgkin lymphoma (n=83), and 37% in indolent or mantle-cell lymphoma (n=65). Older patient age was associated with a significantly higher risk of grade 2 to 4 acute GVHD but not grade 3 to 4 acute or chronic GVHD. No statistically significant associations were found between older age (relative to age 50 to 59 years or as a continuous variable) and NRM, relapse, or survival. CONCLUSION NMA haplo-BMT with post-transplantation cyclophosphamide has encouraging safety and survival outcomes in patients age 50 to 75 years. In patients otherwise fit for BMT, the results support consideration of this approach despite advanced age.

Effects of imatinib and interferon on primitive chronic myeloid leukaemia progenitors

Imatinib has impressive activity against chronic myeloid leukaemia (CML), but does not appear to completely eradicate the disease. Although responses to interferon‐alpha (IFN) are slower and less dramatic than those to imatinib, they can be durable even after discontinuation of the drug. Unlike imatinib, the specific mechanisms responsible for IFNs clinical activity in CML are unknown. We found that IFN induced a G1 cell cycle arrest, as well as terminal differentiation, of the CML cell line KT‐1 and CML CD34+ cells from clinical specimens. Myeloid growth factors augmented the antileukaemic activity of IFN, and neutralising antibodies directed against myeloid growth factors inhibited IFNs antileukaemic activity. We next directly compared the effects of imatinib and IFN against differentiated and primitive CML progenitors from newly‐diagnosed patients. Although less active against CML granulocyte‐macrophage colony forming units than imatinib, IFN was significantly more toxic to primitive CML progenitors responsible for the maintenance of long‐term cultures. Imatinib and IFN appear to have divergent effects on CML progenitors at different stages of maturation, with imatinib more active against differentiated CML progenitors and IFN more active against primitive CML progenitors. The different target cells for these agents may explain the disparities in the kinetics and durability of their clinical responses. At least part of the clinical effect of IFN in CML appears to result from its ability to differentiate primitive CML progenitors.

High-dose cyclophosphamide for severe aplastic anemia: long-term follow-up

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure disorder that can be treated with bone marrow transplantation, immunosuppressive therapy, and high-dose cyclophosphamide. Here, we report long-term follow-up on 67 SAA patients (44 treatment-naive and 23 refractory) treated with high-dose cyclophosphamide. At 10 years, the overall actuarial survival was 88%, the response rate was 71% with the majority being complete, and the actuarial event-free survival was 58% in 44 treatment-naive SAA patients. Patients with refractory SAA fared less well after high-dose cyclophosphamide therapy; at 10 years, overall actuarial survival, response, and actuarial event-free survival rates were 62%, 48%, and 27%, respectively. High-dose cyclophosphamide is highly effective therapy for severe aplastic anemia. Large randomized controlled trials will be necessary to establish how results of high-dose cyclophosphamide compare with either bone marrow transplantation or standard immunosuppressive regimens, such as antithymocyte globulin and cyclosporine.