HLA-matched unrelated donor hematopoietic cell transplantation after nonmyeloablative conditioning for patients with chronic myeloid leukemia

Intensified Mycophenolate Mofetil Dosing and Higher Mycophenolic Acid Trough Levels Reduce Severe Acute Graft-versus-Host Disease after Double-Unit Cord Blood Transplantation

Although mycophenolate mofetil (MMF) has replaced corticosteroids as immunosuppression in cord blood transplantation (CBT), optimal MMF dosing has yet to be established. We intensified MMF dosing from every 12 to every 8 hours to augment graft-versus-host disease (GVHD) prophylaxis in double-unit cord blood transplantation (dCBT) and evaluated outcomes according to the total daily MMF dose/kg in 174 dCBT recipients (median age, 39 years; range, 1 to 71) who underwent transplantation for hematologic malignancies. Recipients of an MMF dose ≤ the median (36 mg/kg/day) had an increased day 100 grade III and IV acute GVHD (aGVHD) incidence compared with patients who received >36 mg/kg/day (24% versus 8%, P = .008). Recipients of ≤ the median dose who had highly HLA allele (1 to 3 of 6) mismatched dominant units had the highest day 100 grade III and IV aGVHD incidence of 37% (P = .009). This finding was confirmed in multivariate analysis (P = .053). In 83 patients evaluated for mycophenolic acid (MPA) troughs, those with a mean week 1 and 2 trough < .5 μg/mL had an increased day 100 grade III and IV aGVHD of 26% versus 9% (P = .063), and those who received a low total daily MMF dose and had a low mean week 1 and 2 MPA trough had a 40% incidence (P = .008). Higher MMF dosing or MPA troughs had no impact on engraftment after myeloablation. This analysis supports intensified MMF dosing in milligram per kilogram per day and MPA trough level monitoring early after transplantation in dCBT recipients.

Sequential therapy combining clofarabine and T-cell-replete HLA-haploidentical haematopoietic SCT is feasible and shows efficacy in the treatment of refractory or relapsed aggressive lymphoma

Prognosis is poor for patients with biologically aggressive Non-Hodgkin lymphoma (NHL), refractory to chemotherapy or relapsed after autologous transplantation, especially when no disease control before allogeneic transplantation is achieved. In 16 patients (median age 53, median prior regimes 5) with relapsed or refractory non-remission NHL, we analysed retrospectively the efficacy of a sequential therapy comprising clofarabine re-induction followed by a reduced-intensity conditioning with fludarabine, CY and melphalan, and T-cell-replete HLA-haploidentical transplantation. High-dose CY was utilized post-transplantation. All patients engrafted. Early response (day +30) was achieved in 94%. Treatment-related grade III-IV toxicity occurred in 56%, most commonly transient elevation of transaminases (36%), while there was a low incidence of infections (19% CMV reactivation, 19% invasive fungal infection) and GVHD (GVHD: acute III-IV: 6%; mild chronic: 25%). One-year non-relapse mortality was 19%. After a median follow-up of 21 months, estimated 1- and 2-year PFS was 56 and 50%, respectively, with 11 patients (69%) still alive after 2 years. In summary, sequential therapy is feasible and effective and provides an acceptable toxicity profile in high-risk non-remission NHL. Presumably, cytotoxic reinduction with clofarabine provides enough remission time for the graft-versus lymphoma effect of HLA-haploidentical transplantation to kick in, even in lymphomas that are otherwise chemo-refractory.

Low tumor burden is associated with early B-cell reconstitution and is a predictor of favorable outcome after non-myeloablative stem cell transplant for chronic lymphocytic leukemia

Abstract Reconstitution, engraftment kinetics and tumor cell clearance were analyzed after reduced intensity conditioning hematopoietic cell transplant (RIC-HCT) in patients with chronic lymphocytic leukemia (CLL). Patients were transplanted from unrelated (n = 40) or related (n = 10) donors after fludarabine and 2 Gy total body irradiation followed by cyclosporine and mycophenolate mofetil. The vast majority of patients (96%) engrafted with absolute neutrophil count (ANC) > 0.5 × 10(9)/L at day + 22. CLL cells decreased (median 2%, range 0-69%) within 28 days, but disappeared by day + 180 after HCT. Donor T-cell chimerism increased to > 95% at day 56 and donor B-cell chimerism to 94% at day + 360. Overall survival was 51 ± 8%, incidence of progression 37 ± 7% and non-relapse related mortality (NRM) 30 ± 7% at 4 years. The most common causes of NRM were graft-versus-host disease (GvHD) (14%) and sepsis (6%). Disease status at HCT was significantly associated with early B-cell reconstitution (p = 0.04) and with increased risk of relapse/progression in univariate and multivariate analysis (p = 0.022). Tumor cells were undetectable by day + 180, although B-cell reconstitution did not occur until 1.5 years after RIC-HCT. The best predictors for progression-free survival (PFS) and overall survival (OS) were complete response (CR) or first partial response (PR1) and the absence of bulky disease at transplant, respectively.

Outcome of second allogenic stem cell transplantation in pediatric patients with non-malignant hematological and immune deficiency disorders

BACKGROUND

Second stem cell transplantation (SCT) is usually associated with high morbidity and mortality and the data on its outcome in pediatric patients with non-malignant disorders are scarce.

PATIENTS AND METHODS

We present 30 children with non-malignant conditions who underwent second SCT at our institution for graft failure after the first SCT; 20 had a non-malignant hematological disorder and 10 had an immune deficiency disorder. Median age at the second SCT was 6.1 years (range, 0.4-13 years) and median time from the first SCT to the second SCT was 6.2 months (range, 1.2-96 months).

RESULTS

Twenty patients (70%) engrafted; severe acute GVHD developed in four patients (13%), and chronic GVHD developed in two patients of those at risk (10%). Thirteen deaths occurred and nine were considered treatment related. The 5-year overall (OS) and event free survival (EFS) for all patients were 53% and 47% respectively. The interval between the two transplants seemed to affect the outcome; patients who had the second SCT ≥ 6 months from the first SCT had better survival; the 5-year OS for the two groups (<6 months and ≥ 6 months) respectively were 30% and 74% (P = 0.004), and the 5-year EFS were 27% and 66% (P = 0.004). The underlying disease did not affect the outcome nor did the use of radiation in the conditioning regimen for the second SCT.

CONCLUSIONS

Second SCT for graft failure should be considered for children with non-malignant hematological and immune deficiency disorders.

Nonmyeloablative allogeneic hematopoietic cell transplantation in patients with acute myeloid leukemia

PURPOSE

Allogeneic hematopoietic cell transplantation (HCT) after high-dose conditioning regimens imposes prohibitively high risks of morbidity and mortality for patients with high-risk acute myeloid leukemia (AML) who are older or have comorbid conditions. Here, we examined outcomes after nonmyeloablative allogeneic HCT in such patients.

PATIENTS AND METHODS

Two hundred seventy-four patients (median age, 60 years) with de novo or secondary AML underwent allogeneic HCT from related (n = 118) or unrelated donors (n = 156) after conditioning with 2 Gy of total-body irradiation (TBI) with or without fludarabine. A calcineurin inhibitor and mycophenolate mofetil were used for postgrafting immunosuppression.

RESULTS

With a median follow-up of 38 months in surviving patients, the estimated overall survival at 5 years was 33%. The estimated 5-year relapse/progression and nonrelapse mortality rates were 42% and 26%, respectively. The cumulative incidences of grades 2, 3, and 4 acute graft-versus-host disease (GVHD) were 38%, 9%, and 5%, respectively. The cumulative incidence of chronic GVHD at 5 years was 44%. Patients in first and second complete remission had better survival rates than patients with more advanced disease (37% and 34% v 18%, respectively). Patients with HLA-matched related or unrelated donors had similar survivals. Unfavorable cytogenetic risk status was associated with increased relapse and subsequent mortality. Chronic GVHD was associated with lower relapse risk.

CONCLUSION

Allogeneic HCT from related or unrelated donors after conditioning with low-dose TBI and fludarabine, relying almost exclusively on graft-versus-leukemia effects, can result in long-term remissions in older or medically infirm patients with AML.

Graft-versus-leukemia effect of nonmyeloablative stem cell transplantation

Nonmyeloablative stem cell transplantation (NST) is increasingly used with beneficial effects because it can be applied to older patients with hematological malignancies and those with various complications who are not suitable for conventional myeloablative stem cell transplantation (CST). Various conditioning regimens differ in their myeloablative and immunosuppressive intensity. Regardless of the type of conditioning regimen, graft-versus- host disease (GVHD) in NST occurs almost equally in CST, although a slightly delayed development of acute GVHD is observed in NST. Although graft-versus-hematological malignancy effects (i.e., graft-versus-leukemia effect, graft-versus-lymphoma effect, and graft-versus-myeloma effect) also occur in NST, completely eradicating residual malignant cells through allogeneic immune responses is insufficient in cases with rapidly growing disease or uncontrolled progressive disease. Donor lymphocyte infusion (DLI) is sometimes combined to support engraftment and to augment the graft-versus-hematological malignancy effect, such as the graft-versus-leukemia effect. DLI is especially effective for controlling relapse in the chronic phase of chronic myelogenous leukemia, but not so effective against other diseases. Indeed, NST is a beneficial procedure for expanding the opportunity of allogeneic hematopoietic stem cell transplantation to many patients with hematological malignancies. However, a more sophisticated improvement in separating graft-versus-hematological malignancy effects from GVHD is required in the future.

Total body irradiation before an allogeneic stem cell transplantation: is there a magic dose?

PURPOSE OF REVIEW

To review the outcomes of allogeneic transplantation with regimens of varying total body irradiation (TBI) doses (0-1575 cGy), with an emphasis on reduced-intensity conditioning (RIC) regimens.

RECENT FINDINGS

RIC regimens with a broad range of TBI doses (0, 200, 400, 550, and 800 cGy) have been studied. Durable donor stem cell engraftment occurred in most patients, with a low rate of toxicity and nonrelapse mortality. Patients excluded from myeloablative regimens were able to tolerate RIC regimens. Retrospective comparisons of patients treated with RIC and myeloablative regimens showed lower nonrelapse mortality but higher relapse risk with RIC; however, overall survivals were similar though a larger fraction of RIC patients had high-risk pretransplant features. Study design weaknesses limit the ability to generalize and apply these results. RIC and myeloablative TBI-based regimens result in durable engraftment of donor stem cells, tolerable toxicity, and acceptable rates of relapse risk and overall survival. Determination of the optimal dose of TBI for allogeneic transplantation is complex and depends on several variables and may vary based on a specific permutation of these variables.

SUMMARY

A broad range of TBI doses for RIC regimens are effective; however, all conclusions are limited by the lack of prospective, randomized trials comparing RIC and myeloablative regimens.

Comparison of outcomes of HLA-matched related, unrelated, or HLA-haploidentical related hematopoietic cell transplantation following nonmyeloablative conditioning for relapsed or refractory Hodgkin lymphoma

We compared the outcome of nonmyeloablative allogeneic hematopoietic cell transplantation (HCT) for patients with relapsed or refractory Hodgkin lymphoma (HL) based on donor cell source. Ninety patients with HL were treated with nonmyeloablative conditioning followed by HCT from HLA-matched related, n=38, unrelated, n=24, or HLA-haploidentical related, n=28 donors. Patients were heavily pretreated with a median of 5 regimens and most patients had failed autologous HCT (92%) and local radiation therapy (83%). With a median follow-up of 25 months, 2-year overall survivals, progression-free survivals (OS)/(PFS), and incidences of relapsed/progressive disease were 53%, 23%, and 56% (HLA-matched related), 58%, 29%, and 63% (unrelated), and 58%, 51%, and 40% (HLA-haploidentical related), respectively. Nonrelapse mortality (NRM) was significantly lower for HLA-haploidentical related (P=.02) recipients compared to HLA-matched related recipients. There were also significantly decreased risks of relapse for HLA-haploidentical related recipients compared to HLA-matched related (P=.01) and unrelated (P=.03) recipients. The incidences of acute grades III-IV and extensive chronic graft-versus-host disease (aGVHD, cGVHD) were 16%/50% (HLA-matched related), 8%/63% (unrelated), and 11%/35% (HLA-haploidentical related). These data suggested that salvage allogeneic HCT using nonmyeloablative conditioning provided antitumor activity in patients with advanced HL; however, disease relapse/progression continued to be major problems. Importantly, alternative donor stem cell sources are a viable option.

Non-myeloablative allogeneic haematopoietic cell transplantation for relapsed diffuse large B-cell lymphoma: a multicentre experience

Patients with relapsed diffuse large B-cell lymphoma (DLBCL) who have failed or are ineligible for autologous haematopoietic cell transplantation (HCT) have a poor prognosis. We examined the outcomes of non-myeloablative allogeneic HCT in this setting. Thirty-one patients with DLBCL and one patient with Burkitt lymphoma received allogeneic HCT following 2 Gy total body irradiation with or without fludarabine. Median age was 52 years. Twenty-four patients (75%) had undergone prior autologous HCT. Disease status at HCT was complete response (14/32, 44%), partial response (9/32, 28%), or refractory (9/32, 28%). Cumulative incidences of acute graft-versus-host disease (GVHD) grades II-IV, grades III-IV, and chronic GVHD were 53%, 19%, and 47% respectively. With a median follow-up of 45 months, 3-year estimated overall (OS) and progression-free survival (PFS) was 45% and 35% respectively. Three-year cumulative incidences of relapse and non-relapse mortality were 41% and 25% respectively. In multivariate models, chemosensitive disease and receipt of >or=4 lines of treatment before HCT were associated with better OS. Patients with chemosensitive disease had 3-year OS and PFS of 56% and 43% respectively. Non-myeloablative allogeneic HCT can produce long-term disease-free survival in patients with chemosensitive relapsed DLBCL who have failed or are ineligible for autologous HCT.

Graft rejection after hematopoietic cell transplantation with nonmyeloablative conditioning

Graft rejection after hematopoietic cell transplantation (HCT) with nonmyeloablative conditioning is a rare but serious clinical problem. Graft rejection and salvage therapy in eight patients in a retrospective analysis of 124 consecutive patients is reported. The patients were conditioned with low-dose fludarabine and total body irradiation (TBI). The association of pretransplantation risk factors with rejection and the effect of chimerism and graft-versus-host disease on rejection were analyzed. Overall survival (OS) and progression free survival (PFS) were compared between patients with and without rejection. Retransplantation was performed with increased TBI conditioning for all patients, and with increased mycophenolate mofetil doses for recipients with HLA-identical sibling donors. No known pretransplantation risk factors were confirmed in this study. Rejection episodes were unevenly distributed over time. The storage temperature of the apheresis products was identified as a risk factor for rejection. Storage of the apheresis products at 5 degrees C diminished the risk of rejection. Low donor T cell chimerism at Day +14 significantly increased the risk of rejection. Seven patients were retransplanted. All but one engrafted successfully, but with decreased OS and PFS. Two patients received pentostatin infusion prior to donor lymphocyte infusions in unsuccessful attempts at reversing rejection. Storage temperature and donor chimerism had a significant effect on rejection. Following rejection, patients are at greater risk of dying from infections and progression/relapse of their malignancy. Retransplantation is feasible and well tolerated after HCT with nonmyeloablative conditioning and should be performed without delay in patients with imminent and manifest graft rejection.

A novel phenotypic method to determine fludarabine triphosphate accumulation in T-lymphocytes from hematopoietic cell transplantation patients

PURPOSE

Fludarabine is an integral anticancer agent for patients with chronic lymphocytic leukemia (CLL) and those receiving conditioning regimens prior to allogeneic hematopoietic cell transplantation (HCT). An individual's response to fludarabine may be influenced by the amount of CD4(+) and CD8(+) T-lymphocyte suppression. Fludarabine undergoes cellular uptake and activation to form the cytotoxic metabolite, fludarabine triphosphate (F-ara-ATP).

METHODS

We have previously developed a highly sensitive LC-MS method to quantitate intracellular F-ara-ATP concentrations in a leukemic cell line. However, quantitation of F-ara-ATP concentrations within CD4(+) and CD8(+) T-lymphocytes from pharmacokinetic blood samples obtained from patients receiving fludarabine therapy is not feasible because of the limited number of T-lymphocytes that can be isolated from each blood sample. Thus, we sought to determine F-ara-ATP accumulation after ex vivo exposure of freshly isolated human CD4(+) or CD8(+) T-lymphocytes to fludarabine. The method was optimized in T-lymphocytes obtained from healthy volunteers, and proved to be a feasible method to determine F-ara-ATP accumulation in patients undergoing HCT.

RESULTS

Considerable variability was observed in F-ara-ATP accumulation in HCT patients (10.5- and 12.5-fold in CD4(+) and CD8(+) cells, respectively), compared to healthy volunteers (1.6- and 1.9-fold in CD4(+) and CD8(+) cells, respectively). Larger variability was also observed in gene expression of transporters and enzymes involved in F-ara-ATP accumulation in HCT patients; however, F-ara-ATP accumulation was not correlated with gene expression, which is in agreement with previous studies.

CONCLUSIONS

The quantitation of F-ara-ATP accumulation in T-lymphocytes provides a novel tool to evaluate patient sensitivity to fludarabine. This tool can be used in future studies to evaluate whether intracellular F-ara-ATP accumulation is associated with efficacy and/or toxicity in patients receiving fludarabine.

Nonmyeloablative Allogeneic Hematopoietic Cell Transplantation in Relapsed, Refractory, and Transformed Indolent Non-Hodgkin's Lymphoma

Purpose

Few effective treatment options exist for chemotherapy-refractory indolent or transformed non-Hodgkin's lymphoma (NHL). We examined the outcome of nonmyeloablative allogeneic hematopoietic cell transplantation (HCT) in this setting.

Patients and Methods

Sixty-two patients with indolent or transformed NHL were treated with allogeneic HCT from related (n = 34) or unrelated (n = 28) donors after conditioning with 2 Gy of total-body irradiation with or without fludarabine. Nine unrelated donors were mismatched for ≥ one HLA antigen. Sixteen patients had histologic transformation before HCT. Twenty patients (32%) had progressive disease after previous high-dose therapy with autologous HCT. Median age was 54 years, and patients had received a median of six lines of treatment before HCT. Median follow-up time after HCT was 36.6 months.

Results

At 3 years, the estimated overall survival (OS) and progression-free survival (PFS) rates were 52% and 43%, respectively, for patients with indolent disease, and 18% and 21%, respectively, for patients with transformed disease. Patients with indolent disease and related donors (n = 26) had 3-year estimated OS and PFS rates of 67% and 54%, respectively. The incidences of grade 2 to 4 acute graft-versus-host disease (GVHD), grade 3 and 4 acute GVHD, and extensive chronic GVHD were 63%, 18%, and 47%, respectively. Among survivors, the median Karnofsky performance status at last follow-up was 85%.

Conclusion

Nonmyeloablative allogeneic HCT can produce durable disease-free survival in patients with relapsed or refractory indolent NHL, even in this relatively elderly and heavily pretreated cohort. Outcomes were particularly good in patients with untransformed disease and related donors, whereas patients with transformed disease did poorly. Long-term survivors reported good overall functional status.

HLA-mismatched/haploidentical hematopoietic stem cell transplantation without in vitro T cell depletion for chronic myeloid leukemia: improved outcomes in patients in accelerated phase and blast crisis phase

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only proven curative therapy for chronic myeloid leukemia (CML), but lack of human leukocyte antigen (HLA)-matched sibling or unrelated donors has restricted its application. Recently, we developed an effective method for haploidentical allo-HSCT achieving comparable outcomes to HLA-identical transplantation.

AIM

To evaluate the outcomes of CML patients who underwent haploidentical allo-HSCT.

METHODS

Ninety-three patients were treated with a modified busulfan (BU)/cyclophosphamide (CY) 2 regimen, including antithymocyte globulin followed by unmanipulated blood and marrow transplantation.

RESULTS

Our data showed that the cumulative incidence of acute graft-versus-host disease (GVHD) was 64.52%, and grade III-IV was 26.45%, 61.79% had chronic GVHD, and 28.93% had extensive chronic GVHD. Non-relapse mortality varied at 8.72% (100 days), 20.72% (1 year) and 20.72% (2 years). Probability of 1-year and 4-year leukemia-free survival was similar in chronic phase (CP) 1, CP2/CR2, accelerated phase, and blast crisis patients. Probability of 4-year overall survival varied as 76.5% (CP1), 85.7% (CP2/CR2), 73.3% (accelerated phase), and 61.5% (blast crisis). Multivariate analysis indicated that factors affecting transplantation outcomes were HLA-B+DR mismatches versus others for II-III acute GVHD and III-IV acute GVHD, the stage of disease at transplantation for relapse, and the time from diagnosis to transplantation for leukemia-free survival, overall survival, and transplantation-related mortality. In our protocol, survival of HSCT for advanced CML was similar to stable stage.

CONCLUSIONS

For patients lacking an HLA-identical related donor, haploidentical relatives are alternative HSCT donors.

Current status of reduced-intensity allogeneic stem cell transplantation using alternative donors

The optimal donor for a patient undergoing reduced-intensity stem cell transplantation remains a human leukocyte antigen (HLA)-matched relative. Alternative donors such as matched unrelated donors (MUDs), mismatched related donors (haploidentical), or unrelated umbilical cord blood (UCB) units have emerged as options as well. The most experience thus far has been with MUD donors, mostly attributed to the development of allele-specific DNA-based HLA-typing methods. The biggest drawback remains the significant delay needed to locate a donor. Haploidentical donors exist for almost all patients, and offer the convenience of a living related donor. However, significant rates of graft-versus-host disease (GVHD) and other toxicities continue to complicate such HLA mismatching. UCB is the most recent option for source of stem cells. Frozen cord blood units can be acquired almost immediately and are able to safely traverse 1 or 2-HLA antigen mismatch barriers. The experience with UCB has been limited by the low cell dose, although recent innovations are attempting to overcome this. In this review, we summarize the current experience and knowledge with alternative donors as stem cell sources for reduced-intensity transplantation.

Extended mycophenolate mofetil and shortened cyclosporine failed to reduce graft-versus-host disease after unrelated hematopoietic cell transplantation with nonmyeloablative conditioning

We previously reported data from 103 patients with hematologic malignancies (median age 54 years) who received peripheral blood stem cell (PBSC) grafts from HLA-matched unrelated donors after nonmyeloablative conditioning and were given postgrafting immunosuppression consisting of mycophenolate mofetil (MMF; administered from day 0 until day +40 with taper through day +96) and cyclosporine (CSP; given from day -3 to day +100, with taper through day 180) (historical patients). The incidences of grade II-IV acute and extensive chronic graft-versus-host disease (aGVHD, cGVHD) were 52% and 49%, respectively, and the 1-year probabilities of relapse, nonrelapse mortality (NRM), and progression-free survival (PFS) were 26%, 18%, and 56%, respectively. Here, we treated 71 patients with hematologic malignancies (median age 56 years) with unrelated PBSC grafts and investigated whether postgrafting immunosuppression with an extended course of MMF, given at full dosing until day +150 and then tapered through day +180, and a shortened course of CSP, through day +80, would promote tolerance induction and reduce the incidence of GVHD (current patients). We observed 77% grade II-IV aGVHD and 45% extensive cGVHD (P=.03, and P=.43, respectively, in current compared to historical patients). The 1-year probabilities of relapse, NRM, and PFS were 23%, 29%, and 47%, respectively (P=.89, P=.02, and P=.08 compared to the historical patients). We conclude that postgrafting immunosuppression with extended MMF and shortened CSP failed to decrease the incidence of GVHD among unrelated PBSC recipients given nonmyeloablative conditioning.

Hematopoietic cell transplantation in patients with myelodysplastic syndrome or acute myeloid leukemia arising from myelodysplastic syndrome: similar outcomes in patients with de novo disease and disease following prior therapy or antecedent hematologic disorders

We analyzed outcomes after hematopoietic cell transplantation (HCT) in 257 patients, 3 to 72.7 years old (median, 43 y), with secondary myelodysplastic syndrome (MDS) including those with transformation to acute myeloid leukemia (tAML). Conditioning regimens included high-dose total-body irradiation (TBI)/chemotherapy (n = 83); busulfan (BU)/cyclophosphamide (CY) (BUCY, n = 122; with BU targeting [tBUCY], n = 93); fludarabine (Flu) with tBU (FLUtBU; n = 12); Flu plus 200 cGy TBI (n = 26); and miscellaneous regimens (n = 14). Donors were HLA-identical or partially mismatched family members in 135 and unrelated individuals in 122 patients. Five-year relapse-free survival was highest (43%) and nonrelapse mortality lowest (28%) among tBUCY-conditioned patients. Outcomes were compared with results in 339 patients who received transplants for de novo MDS/tAML, and a multivariate analysis failed to show significant differences in outcome between the 2 cohorts. Relapse probability and relapse-free survival correlated significantly with disease stage (P < .001) and karyotype (P < .001). Relapse incidence was lower (P = .003) and relapse-free survival superior (P = .02) with unrelated donor transplants. The data suggest that overall inferior outcome in patients with secondary MDS/tAML was related to the frequency of high-risk cytogenetics. For both cohorts, transplantation outcomes improved over the time interval studied.

Hematopoietic cell transplantation after reduced-intensity conditioning for older adults with acute myeloid leukemia in complete remission

PURPOSE OF REVIEW

Allogeneic hematopoietic cell transplantation with myeloablative conditioning is a well established therapy for patients with acute myeloid leukemia. Its efficacy depends, in part, on the destruction of recipient acute myeloid leukemia cells by the conditioning regimen and, in part on their removal by donor immune cells contained in the graft (graft-versus-tumor effect). Due to regimen-related toxicities, the use of myeloablative allogeneic hematopoietic cell transplantation has been restricted to younger patients in good condition. More recently, the introduction of allogeneic hematopoietic cell transplantation following reduced-intensity or nonmyeloablative conditioning regimens, which rely mainly on graft-versus-tumor effects for tumor cell eradication, has permitted extending hematopoietic cell transplantation to include older patients and those with medical comorbidities.

RECENT FINDINGS

Early results with allogeneic hematopoietic cell transplantation after nonmyeloablative and reduced-intensity conditioning for patients with acute myeloid leukemia in first complete remission are encouraging, with 2-year survivals after hematopoietic cell transplantation ranging from 48 to 79% among studies. Further, retrospective studies have demonstrated similar outcomes in adult patients with acute myeloid leukemia in complete remission given either myeloablative or nonmyeloablative conditioning.

SUMMARY

Prospective studies are needed to define the place of allogeneic hematopoietic cell transplantation after nonmyeloablative or reduced-intensity conditioning in patients with acute myeloid leukemia in complete remission, and to determine a role for consolidation chemotherapy before hematopoietic cell transplantation, if any.

Partially Matched, Nonmyeloablative Allogeneic Transplantation: Clinical Outcomes and Immune Reconstitution

Purpose

Allogeneic transplantation is typically limited to younger patients having a matched donor. To allow a donor to be found for nearly all patients, we have used a nonmyeloablative conditioning regimen in conjunction with stem cells from a related donor with one fully mismatched HLA haplotype.

Patients and Methods

Fludarabine, cyclophosphamide, and alemtuzumab were used as the preparatory regimen. Additional graft-versus-host disease (GVHD) prophylaxis included mycophenolate with or without cyclosporine. Patients with persistence of disease had a donor lymphocyte boost planned. Toxicities, engraftment, response, survival, and immune recovery are reported.

Results

Forty-nine patients with hematologic malignancies or marrow failure and no other available donors were enrolled. Ninety-four percent of patients had successful engraftment, and 8% had secondary graft failure. The treatment-related mortality rate was 10.2%, and 8% of patients had severe GVHD. Encouraging evidence of quantitative lymphocyte recovery through expansion of transplanted T cells was noted by 3 to 6 months. Seventy-five percent of patients attained a complete remission, and 1-year survival rate was 31% (95% CI, 18% to 44%). A standard-risk group of 19 patients with aplasia or in remission at transplantation demonstrated a 63% 1-year survival rate (95% CI, 38% to 80%) and 2.9-year median overall survival time (95% CI, 6.2 to 48 months).

Conclusion

Nonmyeloablative therapy using haploidentical family member donors is feasible because the main obstacles of GVHD and graft rejection are manageable, allowing readily available stem-cell donors to be found for nearly all patients. Further qualitative and quantitative improvement in immune recovery is needed to address the high rate of relapse and risk of severe infections.

Failure of donor lymphocyte infusion to prevent graft rejection in dogs given DLA-identical marrow after 1 Gy of total body irradiation

We investigated in a preclinical canine model of hematopoietic cell transplantation (HCT) whether preemptive donor lymphocyte infusion (DLI) given 1 month after HCT could prevent late graft rejection that was the rule in historical dogs given suboptimal conditioning with 1 Gy of total body irradiation (TBI) before and immunosuppression with cyclosporine (CSP) and either mycophenolate mofetil (MMF; n = 6) or rapamycin (n = 5) after dog leukocyte antigen (DLA)-identical marrow transplantation. Nine dogs given DLA-identical marrow after 1 Gy of TBI followed by postgrafting MMF and CSP were studied. A single DLI was given 28-36 days after HCT, either with (n = 5) or without (n = 4) preceding treatment with the immunosuppressive drug pentostatin. Two of the 4 dogs given DLI only maintained stable mixed donor-host chimera beyond 30 weeks after HCT, whereas 2 rejected their grafts, on weeks 10 and 15 after HCT. One of the 5 dogs given pentostatin before DLI maintained a stable mixed donor-host chimera beyond 30 weeks, whereas 4 rejected their grafts, at weeks 8, 12, 12, and 16 after HCT. The 30-week probability of stable mixed chimerism was 33% among dogs given DLI, versus 0% among 11 historical dogs (P = .003). In conclusion, DLI was only moderately effective in preventing graft rejection in this model. Additional immunosuppression with pentostatin did not improve that outcome. The model might be useful in developing potential strategies aimed at preventing graft rejection in patients with low donor chimerism levels.

Unrelated donor granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cell transplantation after nonmyeloablative conditioning: the effect of postgrafting mycophenolate mofetil dosing

We previously reported results in 71 patients with advanced hematologic malignancies given HLA-matched unrelated granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cell (G-PBMC) grafts after fludarabine 90 mg/m(2), 2 Gy of total body irradiation, and postgrafting mycophenolate mofetil (MMF) 15 mg/kg twice daily and cyclosporine 6.25 mg/kg twice daily orally. Graft rejection was 15%; the cumulative probability of acute graft-versus-host disease (GVHD) was 52%. According to MMF pharmacokinetic studies, which showed a short half-life of its active metabolite, mycophenolic acid, we increased MMF dosing from 15 mg/kg twice daily to 15 mg/kg 3 times daily to increase immunosuppression and reduce the incidence of both graft rejection and acute GVHD. Among 103 patients so treated, graft rejection occurred in 5%, whereas acute GVHD remained at 53%. Outcomes were compared with results of previous G-PBMC recipients given MMF twice daily. Infection rates were slightly higher with MMF 3 times daily than with MMF twice daily. Nevertheless, 2-year nonrelapse mortality and overall and progression-free survivals were similar for MMF 3-times-daily and twice-daily patients (19%, 58%, and 49% versus 20%, 48%, and 37%, respectively). Nonmyeloablative conditioning with postgrafting cyclosporine and MMF given 3 times daily allowed 95% durable engraftment of unrelated donor G-PBMC grafts.

The immune system as a foundation for immunologic therapy and hematologic malignancies: a historical perspective

In this review we aim to provide a historical overview of the immunotherapeutic approaches which have been developed for the treatment of hematological malignancies. After briefly summarizing the development of the theory of cancer immune surveillance, we describe how initial studies discovering the efficacy of the immune-mediated graft-versus-tumor effects after allogeneic hematopoietic cell transplantation led to new transplantation approaches (termed non-myeloablative transplantation) relying almost exclusively on graft-versus-tumor effects for tumor eradication. We then summarize important steps in the development of tumor vaccines and autologous adoptive immunotherapy in patients with hematological malignancies. Finally, we describe historical discoveries leading to the recent success with monoclonal antibodies as treatment for lymphomas, chronic lymphocytic leukemia, and acute myeloid leukemia.

Unrelated Donor Status and High Donor Age Independently Affect Immunologic Recovery after Nonmyeloablative Conditioning

The risk of cytomegalovirus (CMV) infection is higher after HLA-matched unrelated donor (URD) than after HLA-matched related donor (MRD) nonmyeloablative hematopoietic cell transplantation (HCT). We therefore investigated factors affecting immune recovery in 94 patients given HCT from MRDs (n = 51) and URDs (n = 43) after 2-Gy total body irradiation with or without fludarabine and postgrafting immunosuppression with mycophenolate mofetil and cyclosporine. CD4 T cells counts remained below normal values during the first year after HCT in both patient groups. This included abnormally low counts each of naive CD4 T cells and memory CD4 T cells. Conversely, CD8 T cell counts reached the 10th percentile of normal 6 months after HCT in MRD and URD recipients. On day 30 after HCT, URD recipients had lower counts of B cells (P = .02), naive CD4 T cells (P = .04), memory CD4 T cells (P = .005), memory CD8 T cells (P = .005), and CMV-specific T helper cells (P = .007) than had MRD recipients. This delay in CMV-specific immune reconstitution translated into increased frequency of CMV antigenemia among URD recipients during the first 100 days after HCT. Older donor age was associated with low counts of naive CD4 T cells on days 180-365 after HCT (P = .003). Further, low numbers of T cells and CD34(+) cells in the graft and development of acute graft-versus-host disease were associated with impaired immune recovery of naive CD4 T cells and B cells. In summary, immunologic recovery was poor the first year after nonmyeloablative conditioning and was delayed among URD recipients in comparison with MRD recipients. Other factors significantly associated with delayed immune recovery were advanced donor age, low numbers of CD34 and T cells in the graft, and development of graft-versus-host disease.

Factors associated with outcomes in allogeneic hematopoietic cell transplantation with nonmyeloablative conditioning after failed myeloablative hematopoietic cell transplantation

PURPOSE

Several studies have investigated the feasibility of allogeneic hematopoietic cell transplantations (HCTs) after reduced-intensity conditioning in patients who experienced relapse after myeloablative HCT. Although most studies showed relatively low nonrelapse mortality (NRM) rates and encouraging short-term results, it has yet to be defined which patients would benefit most from these approaches.

PATIENTS AND METHODS

We analyzed data from 147 patients with hematologic malignancies who experienced treatment failure with conventional autologous (n = 135), allogeneic (n = 10), or syngeneic (n = 2) HCT and were treated with HLA-matched related (n = 62) or unrelated (n = 85) grafts after conditioning with 2 Gy of total-body irradiation with or without fludarabine.

RESULTS

Three-year probabilities of NRM, relapse, and overall survival were 32%, 48%, and 27%, respectively, for related recipients, and 28%, 44%, and 44%, respectively, for unrelated recipients. The best outcomes were observed in patients with non-Hodgkin's lymphoma, whereas patients with multiple myeloma and Hodgkin's disease had worse outcomes as a result of high incidences of relapse and progression. Being in partial remission (PR) or complete remission (CR) at HCT (P = .002) and developing chronic graft-versus-host disease (GVHD; P = .03) resulted in lower risks of relapse and progression. Factors associated with better overall survival were PR or CR (P = .01) and lack of comorbidity (P = .03) at HCT and absence of acute GVHD after HCT (P = .06).

CONCLUSION

Encouraging outcomes were seen with allogeneic HCT after nonmyeloablative conditioning in selected patients who had experienced relapse after a high-dose HCT, particularly in patients with non-Hodgkin's lymphoma. Results with unrelated grafts were comparable with results with related grafts.

Chimerism and outcomes after allogeneic hematopoietic cell transplantation following nonmyeloablative conditioning

Allogeneic hematopoietic cell transplantation (HCT) following nonmyeloablative conditioning has been extensively evaluated in patients with hematologic malignancies who are ineligible for conventional HCT because of age or medical comorbidities. Nonmyeloablative regimens have led to an initial state of mixed hematopoietic chimerism defined as coexistence of donor- and host-derived hematopoiesis. While nonmyeloablative regimens have been associated with reduced regimen-related toxicities in comparison with conventional myeloablative conditioning, graft rejection, graft-versus-host disease (GVHD), and disease progression have remained significant challenges. In this article, after briefly introducing current techniques for chimerism assessment, we describe factors affecting donor chimerism levels after nonmyeloablative conditioning, and then review data suggesting that chimerism assessment early after HCT might help identify patients at risk for graft rejection, GVHD and relapse/progression. Finally, we discuss how these observations have opened the way to further research protocols evaluating manipulation of postgrafting immunosuppression, and/or infusion of donor immune cells.

Despite Inhibition of Hematopoietic Progenitor Cell Growth In Vitro, the Tyrosine Kinase Inhibitor Imatinib Does Not Impair Engraftment of Human CD133+Cells into NOD/SCIDβ2mNullMice

There is potential interest for combining allogeneic hematopoietic cell transplantation (HCT), and particularly allogeneic HCT with a nonmyeloablative regimen, to the tyrosine kinase inhibitor imatinib (Glivec; Novartis, Basel, Switzerland, http://www.novartis.com) in order to maximize anti-leukemic activity against Philadelphia chromosome-positive leukemias. However, because imatinib inhibits c-kit, the stem cell factor receptor, it could interfere with bone marrow engraftment. In this study, we examined the impact of imatinib on normal progenitor cell function. Imatinib decreased the colony-forming capacity of mobilized peripheral blood human CD133(+) cells but not that of long-term culture-initiating cells. Imatinib also decreased the proliferation of cytokine-stimulated CD133(+) cells but did not induce apoptosis of these cells. Expression of very late antigen (VLA)-4, VLA-5, and CXCR4 of CD133(+) cells was not modified by imatinib, but imatinib decreased the ability of CD133(+) cells to migrate. Finally, imatinib did not decrease engraftment of CD133(+) cells into irradiated nonobese diabetic/severe combined immunodeficient/beta2m(null) mice conditioned with 3 or 1 Gy total body irradiation. In summary, our results suggest that, despite inhibition of hematopoietic progenitor cell growth in vitro, imatinib does not interfere with hematopoietic stem cell engraftment.

Stable Engraftment after a Conditioning Regimen with Fludarabine and Melphalan for Bone Marrow Transplantation from an Unrelated Donor

Graft failure and nonrelapse mortality (NRM) are major obstacles after the first unrelated-donor bone marrow transplantation (UD-BMT) with reduced-intensity conditioning. We evaluated UD-BMT with fludarabine (5 x 25 mg/m2) and melphalan (2 x 90 mg/m2) treatment combined with short-term methotrexate and tacrolimus (n = 20) or cyclosporine (n = 2) therapy for 22 patients with hematologic malignancies who were ineligible for conventional conditioning. Only 9 patients were in remission at transplantation. Seventeen patients underwent HLA-matched or DRB1 allele-mismatched transplantation, and 5 patients underwent HLA-A allele-mismatched or serologically HLA-DR-mismatched transplantation. Regimen-related toxicities were tolerable, although transient oral mucositis, hepatobiliary enzyme elevation, and diarrhea were observed frequently. All evaluable patients achieved sustained neutrophil engraftment, and all patients tested showed complete donor chimerism on day 28. With a median follow-up of 16 months, NRM and overall survival rates at 1 year were 19% and 81%, respectively, among the patients who underwent HLA-matched or DRB1 allele-mismatched transplantation. Acute graft-versus-host disease (GVHD) of grades II to IV occurred in 26% of the patients. The cumulative incidence of chronic GVHD was 44%. Despite the small number of patients and the short follow-up period, this reduced-intensity regimen enabled satisfactory engraftment and achievement of rapid complete donor chimerism with tolerable toxicities in the patients, including those who underwent HLA-mismatched UD-BMT.

The early referral for reduced-intensity stem cell transplantation in patients with Ph1 (+) chronic myelogenous leukemia in chronic phase in the imatinib era: results of the Latin American Cooperative Oncohematology Group (LACOHG) prospective, multicenter study

Using a reduced-intensity stem cell transplantation (RIST) schedule, 24 patients with Philadelphia (Ph1) (+) chronic myelogenous leukemia (CML) in first chronic phase (CP) were prospectively allografted in four Latin American countries: México, Brazil, Colombia and Venezuela, using HLA-identical siblings as donors. The median age of the patients was 41 years (range 10-71 years); there were eight females. Patients received a median of 4.4 x 10(6)/kg CD34 cells. The median time to achieve above 0.5 x 10(9)/l granulocytes was 12 days, range 0-41 days, and the median time to achieve above 20 x 10(9)/l platelets was also 12 days, range 0-45 days. In all, 22 patients are alive 81-830 (median 497) days after RIST. The 830-day probability of survival is 92%, and the median survival has not been reached, being beyond 830 days. A total of 11 patients (46%) developed acute graft-versus-host disease (GVHD), and seven of 23 (30%) developed chronic GVHD. Two patients died 43 and 210 days after RIST, one as a result of sepsis and the other of chronic GVHD. The 100-day mortality was 4.4%, and transplant-related mortality was 8%. RIST for patients with CML in CP appears to be an adequate therapeutic option.

Outcomes with Myeloid Malignancies

Reduced-intensity conditioning (RIC) regimens were initially introduced to provide allogeneic stem cell transplantation (HCT), a potentially curative procedure for myeloid malignancies, for patients who were not considered eligible for conventional myeloablative HCT either because of advanced age or excessive comorbidities. A variety of RIC regimens have been studied. The exact definition of RIC remains arbitrary and generally depends upon the perceived toxicity of a given regimen rather than the actual dose of chemotherapy or radiotherapy administered. In several published series, RIC regimens have demonstrated a reduction in non-relapse mortality (NRM), thereby accomplishing the initial goal of expanding the patient population eligible for this potentially curative procedure. Most retrospective studies performed to date have shown a decrease in NRM and an increase in relapse-related mortality with the use of RIC as opposed to conventional myeloablative HCT in myeloid malignancies. This appears to be particularly true for patients who are in relapse at the time of HCT. In contrast, patients who are in remission at time of HCT appear to have a reduction in NRM without a subsequent increase in relapse-related mortality. There is interest in applying RIC to younger patients and to patients with fewer comorbidities as they may have a reduction in NRM without a concomitant increase in relapse. Prospective multicenter studies are needed to define the optimal conditioning regimen, which is likely dependent upon a variety of disease-specific and patient-specific factors.

Allogeneic hematopoietic cell transplantation following nonmyeloablative conditioning as treatment for hematologic malignancies and inherited blood disorders

Allogeneic hematopoietic cell transplantation (HCT) after myeloablative conditioning regimens has been an effective treatment for many patients with hematologic malignancies or inherited blood disorders. Unfortunately, such regimens have been associated with significant toxicity, limiting their use to otherwise healthy, relatively young patients. In an attempt to extend treatment by allogeneic HCT to older patients and those with comorbid conditions, several groups of investigators have developed reduced-intensity or truly nonmyeloablative conditioning regimens, lacking such toxicity. Analogous to conventional regimens, reduced-intensity regimens both eliminated host-versus-graft (rejection) reactions and produced major anti-tumor effects. In contrast, nonmyeloablative regimens have relied on optimizing both pre-and posttransplant immunosuppression to overcome host-versus-graft reactions, while anti-tumor responses have depended mainly on immune-mediated graft-versus-tumor effects. In this review, we define reduced-intensity and truly nonmyeloablative regimens, describe the preclinical development and clinical application of a very low intensity nonmyeloablative regimen, and review results with reduced-intensity regimens in patients with hematologic malignancies or inherited blood disorders.

Current status of hematopoietic stem cell transplantation after nonmyeloablative conditioning

PURPOSE OF REVIEW

Allogeneic hematopoietic stem cell transplantation was originally developed as a form of rescue from high-dose chemoradiotherapy, which is given both to eradicate malignancy and provide sufficient immunosuppression for allogeneic engraftment. However, it was observed that allogeneic immunocompetent cells transplanted with the stem cells, or arising from them, mediated therapeutic antitumor effects independent of the action of the high-dose therapy. This was termed a graft-versus-tumor effect. This has prompted the recent development of nonmyeloablative conditioning regimens for allogeneic hematopoietic stem cell transplantation that have opened the way to include elderly patients and those with comorbid conditions.

RECENT FINDINGS

Recent retrospective studies comparing hematopoietic stem cell transplantation after myeloablative or nonmyeloablative regimens suggested that the use of nonmyeloablative conditioning might be associated with lower transplant-related toxicity, lower nonrelapse mortality, and at least similar intermediate-term progression-free survival.

SUMMARY

Hematopoietic stem cell transplantation after nonmyeloablative conditioning might become the procedure of choice also for younger patients. Phase 3 studies are needed to determine outcomes for different diseases and age groups.

High doses of transplanted CD34+ cells are associated with rapid T-cell engraftment and lessened risk of graft rejection, but not more graft-versus-host disease after nonmyeloablative conditioning and unrelated hematopoietic cell transplantation

This report examines the impact of graft composition on outcomes in 130 patients with hematological malignancies given unrelated donor granulocyte-colony-stimulating-factor-mobilized peripheral blood mononuclear cells (G-PBMC) (n = 116) or marrow (n = 14) transplantation after nonmyeloablative conditioning with 90 mg/m(2) fludarabine and 2 Gy TBI. The median number of CD34(+) cells transplanted was 6.5 x 10(6)/kg. Higher numbers of grafted CD14(+) (P = 0.0008), CD3(+) (P = 0.0007), CD4(+) (P = 0.001), CD8(+) (P = 0.004), CD3(-)CD56(+) (P = 0.003), and CD34(+) (P = 0.0001) cells were associated with higher levels of day 28 donor T-cell chimerism. Higher numbers of CD14(+) (P = 0.01) and CD34(+) (P = 0.0003) cells were associated with rapid achievement of complete donor T-cell chimerism, while high numbers of CD8(+) (P = 0.005) and CD34(+) (P = 0.01) cells were associated with low probabilities of graft rejection. When analyses were restricted to G-PBMC recipients, higher numbers of grafted CD34(+) cells were associated with higher levels of day 28 donor T-cell chimerism (P = 0.01), rapid achievement of complete donor T-cell chimerism (P = 0.02), and a trend for lower risk for graft rejection (P = 0.14). There were no associations between any cell subsets and acute or chronic GVHD nor relapse/progression. These data suggest more rapid engraftment of donor T cells and reduced rejection rates could be achieved by increasing the doses of CD34(+) cells in unrelated grafts administered after nonmyeloablative conditioning.