The Impact of Chimerism Patterns and Predonor Leukocyte Infusion Lymphopenia on Survival following T Cell-Depleted Reduced Intensity Conditioned Transplants

Risk factors for graft-versus-host-disease after donor lymphocyte infusion following T-cell depleted allogeneic stem cell transplantation

Introduction

Unmodified donor lymphocyte infusions (DLI) after allogeneic stem cell transplantation (alloSCT) can boost the beneficial Graft-versus-Leukemia (GvL) effect but may also induce severe Graft-versus-Host-Disease (GvHD). To improve the balance between GvL and GvHD, it is crucial to identify factors that influence the alloreactivity of DLI.

Methods

We investigated the effects of the presence of patient-derived antigen-presenting cells at time of DLI as estimated by the bone marrow (BM) chimerism status, lymphopenia as measured by the absolute lymphocyte count (ALC) at time of DLI, and the presence of a viral infection (de novo or reactivation) close to DLI on the risk of GvHD after DLI. The cohort consisted of patients with acute leukemia or myelodysplastic syndrome who prophylactically or pre-emptively received DLI as standard care after alemtuzumab-based alloSCT. In patients at high risk for relapse, DLI was administered at 3 months after alloSCT (n=88) with a dose of 0.3x106 or 0.15x106 T cells/kg in case of a related or unrelated donor, respectively. All other patients (n=76) received 3x106 or 1.5x106 T cells/kg, respectively, at 6 months after alloSCT.

Results

For both DLIs, patients with reduced-intensity conditioning and an unrelated donor had the highest risk of GvHD. For DLI given at three months, viral infection within 1 week before and 2 weeks after DLI was an additional significant risk factor (hazard ratio (HR) 3.66 compared to no viral infection) for GvHD. At six months after alloSCT, viral infections were rare and not associated with GvHD. In contrast, mixed BM chimerism (HR 3.63 for ≥5% mixed chimerism compared to full donor) was an important risk factor for GvHD after DLI given at six months after alloSCT. ALC of <1000x106/l showed a trend for association with GvHD after this DLI (HR 2.05 compared to ≥1000x106/l, 95% confidence interval 0.94-4.45). Furthermore, the data suggested that the presence of a viral infection close to the DLI at three months or ≥5% mixed chimerism at time of the DLI at six months correlated with the severity of GvHD, thereby increasing their negative impact on the current GvHD-relapse-free survival.

Conclusion

These data demonstrate that the risk factors for GvHD after DLI depend on the setting of the DLI.

Mixed T cell lineage chimerism in acute leukemia/MDS using pre-emptive donor lymphocyte infusion strategy-Is it prognostic?-a single-center retrospective study

Pre-emptive DLI (pDLI) is an effective strategy in lowering the risk of relapse without significantly increasing the risk of graft-versus-host disease (GVHD) in the case of T cell lineage mixed chimerism (MC) post allogeneic transplant in hematological malignancies. Many patients, however, fail to receive timely pDLI and have dismal outcomes, which are not taken into consideration. We compared long-term outcomes of 106 patients having T cell MC after day 60 and undergoing allogeneic stem cell allograft for acute leukemia from an unrelated donor (UD), with 111 patients having complete chimerism (CC). Fifty-three (56%) patients received prophylactic pDLI. Thirty-six patients (67%) had a response (RR), 17 (33%) had no response (NR), and fifty-two (54%) did not receive any pDLI (ND). OS was better in MC group as compared to CC (54% vs 43%, p = 0.04), mainly due to reduction in NRM (14% vs 25%, p = 0.05), and all grade acute and chronic GVHD. Within the MC group, response to pDLI was the only significant factor predicting OS, DFS, and relapses with NR and ND having unfavorable outcomes as compared to RR (p = 0.001). T cell MC in patients undergoing UD allografts with alemtuzumab is no longer an adverse prognostic factor, as compared to patients having CC, after timely implementation of pDLI.

Mixed chimerism established by hematopoietic stem cell transplantation is maintained by host and donor T regulatory cells

Transplantation is an effective treatment of many clinical disorders, but the mechanisms that regulate immunological tolerance are uncertain and remain central to improving patient outcome. Hemopoietic stem cell transplantation (SCT) often establishes "mixed chimerism" in which immune cells from both the donor and patient coexist in vivo in a setting of immunological tolerance. We studied immune function in 69 patients within 2 months following SCT; 37 were fully donor and 32 displayed mixed chimerism. The proportion of T regulatory (Treg) cells was increased during mixed chimerism and comprised equal numbers of donor and host-derived regulatory cells. This was associated with a tolerogenic PD-L1⁺ profile on dendritic cells. Importantly, effector T cells from patients with mixed chimerism exhibited reduced cytotoxicity against host target cells in vitro, but this was restored following depletion of CD4⁺ Treg cells. These data show that Treg cells play a major role in sustaining immunological tolerance during mixed chimerism. These insights should help to guide novel interventions to improve clinical transplantation.

Full donor chimerism without graft-versus-host disease: the key factor for maximum benefit of pre-emptive donor lymphocyte infusions (pDLI)

Compared to standard-conditioned regimens, reduced-intensity conditioning and T-cell depletion deliver lower transplant-related mortality and decreased graft-vs-host disease after allogeneic hematopoietic stem-cell transplantation. These advantages may however be mitigated by increased relapse rates and delays in achievement of full donor chimerism (FDC). Pre-emptive donor lymphocyte infusions (pDLI) facilitate the conversion of mixed (MDC) to FDC. However, there is a lack of published data on the risk/benefit analysis of this intervention. We performed a retrospective analysis of 119 patients who received 276 pDLI doses for falling CD3 chimerism, CD3 < 50% or mixed XX/XY karyotype. 71/119(60%) Patients achieved FDC, with only one reverting to MDC. Cumulative incidence (CI) of relapse at 5 years was significantly lower in the FDC group (16.0 vs 41.4%, p < 0.001). Those patients who achieved FDC had improved EFS (p < 0.001) and OS (p < 0.001). Interestingly, patients with FDC who developed DLI-induced graft-vs-host disease (GvHD) showed a similar outcome to those with MDC. The majority of patients who receive pDLI convert to FDC and retain that status. Achievement of FDC after pDLI impacts on survival, and those patients who achieve FDC without GvHD, experience maximum clinical benefit. Strategies to minimise DLI-induced GvHD should be considered to maximise the therapeutic potential of this intervention.

Very early lineage-specific chimerism after reduced intensity stem cell transplantation is highly predictive of clinical outcome for patients with myeloid disease

BACKGROUND

The importance of chimerism status in the very early period after hematopoietic stem cell transplantation is unclear. We determined PBMC and T-cell donor chimerism 50 days after transplantation and related this to disease relapse and overall survival.

METHODS

144 sequential patients underwent transplantation of which 90 had AML/MDS and 54 had lymphoma. 'Full donor chimerism' was defined as ≥99% donor cells and three patient groups were defined: 40% with full donor chimerism (FC) in both PBMC and T-cells; 25% with mixed chimerism (MC) within both compartments and 35% with 'split' chimerism (SC) characterised by full donor chimerism within PBMC and mixed chimerism within T-cells.

RESULTS

In patients with myeloid disease a pattern of mixed chimerism (MC) was associated with a one year relapse rate of 45% and a five year overall survival of 40% compared to values of 8% and 75%, and 17% and 60%, for those with SC or FC respectively. The pattern of chimerism had no impact on clinical outcome for lymphoma.

CONCLUSION

The pattern of lineage-specific chimerism at 50 days after transplantation is highly predictive of clinical outcome for patients with myeloid malignancy and may help to guide subsequent clinical management.

Durable graft-versus-leukaemia effects without donor lymphocyte infusions - results of a phase II study of sequential T-replete allogeneic transplantation for high-risk acute myeloid leukaemia and myelodysplasia

Allogeneic haematopoietic stem-cell transplantation remains the only curative treatment for relapsed/refractory acute myeloid leukaemia (AML) and high-risk myelodysplasia but has previously been limited to patients who achieve remission before transplant. New sequential approaches employing T-cell depleted transplantation directly after chemotherapy show promise but are burdened by viral infection and require donor lymphocyte infusions (DLI) to augment donor chimerism and graft-versus-leukaemia effects. T-replete transplantation in sequential approaches could reduce both viral infection and DLI usage. We therefore performed a single-arm prospective Phase II clinical trial of sequential chemotherapy and T-replete transplantation using reduced-intensity conditioning without planned DLI. The primary endpoint was overall survival. Forty-seven patients with relapsed/refractory AML or high-risk myelodysplasia were enrolled; 43 proceeded to transplantation. High levels of donor chimerism were achieved spontaneously with no DLI. Overall survival of transplanted patients was 45% and 33% at 1 and 3 years. Only one patient developed cytomegalovirus disease. Cumulative incidences of treatment-related mortality and relapse were 35% and 20% at 1 year. Patients with relapsed AML and myelodysplasia had the most favourable outcomes. Late-onset graft-versus-host disease protected against relapse. In conclusion, a T-replete sequential transplantation using reduced-intensity conditioning is feasible for relapsed/refractory AML and myelodysplasia and can deliver graft-versus-leukaemia effects without DLI.

Multi-state analysis illustrates treatment success after stem cell transplantation for acute myeloid leukemia followed by donor lymphocyte infusion

In the field of hematopoietic stem cell transplantation, the common approach is to focus outcome analyses on time to relapse and death, without assessing the impact of post-transplant interventions. We investigated whether a multi-state model would give insight into the events after transplantation in a cohort of patients who were transplanted using a strategy including scheduled donor lymphocyte infusions. Seventy-eight consecutive patients who underwent myeloablative T-cell depleted allogeneic stem cell transplantation for acute myeloid leukemia or myelodysplastic syndrome were studied. We constructed a multi-state model to analyze the impact of donor lymphocyte infusion and graft-versus-host disease on the probabilities of relapse and non-relapse mortality over time. Based on this model we introduced a new measure for outcome after transplantation which we called 'treatment success': being alive without relapse and immunosuppression for graft-versus-host disease. All relevant clinical events were implemented into the multi-state model and were denoted treatment success or failure (either transient or permanent). Both relapse and non-relapse mortality were causes of failure of comparable magnitude. Whereas relapse was the dominant cause of failure from the transplantation state, its rate was reduced after graft-versus-host disease, and especially after donor lymphocyte infusion. The long-term probability of treatment success was approximately 40%. This probability was increased after donor lymphocyte infusion. Our multi-state model helps to interpret the impact of post-transplantation interventions and clinical events on failure and treatment success, thus extracting more information from observational data.

Preemptive DLI without withdrawal of immunosuppression to promote complete donor T-cell chimerism results in favorable outcomes for high-risk older recipients of alemtuzumab-containing reduced-intensity unrelated donor allogeneic transplant: a prospective phase II trial

Although pretransplant alemtuzumab can reduce GVHD following allogeneic transplantation, it may also increase the risk of mixed donor T-cell chimerism and infections. We hypothesized that the early use of DLI without withdrawal of immunosuppressive drugs in patients with mixed T-cell chimerism would lower the risk of relapse without significantly increasing the risk of GVHD post DLI. Thirty-six patients (median age 59 years) were treated in this phase II trial using reduced-intensity conditioning including s.c. alemtuzumab (total dose 43 mg) and a PBSC graft from a matched unrelated donor (UD). DLI without withdrawal of immunosuppressive drugs was administered to all 25 patients with <50% donor T-cell chimerism on day +60. The cumulative risks of acute and chronic GVHD were 42% and 59%, respectively. Estimated probabilities of non-relapse mortality (NRM) at day 100 and 1 year were 3% and 14%, respectively. With a median follow up 2.4 years, estimated survivals at day 100, 1 and 2 years were 97%, 71% and 57%, respectively. In multivariate analysis, the occurrence of acute GVHD was associated with an increased risk of mortality, whereas the occurrence of chronic GVHD had a protective effect, associated with decreased relapse and improved disease-free survival. Low-dose alemtuzumab and preemptive DLI provides favorable transplant outcomes including low NRM in an older patient population with high-risk malignancies undergoing UD transplantation.

Maximizing GVL in allogeneic transplantation: role of donor lymphocyte infusions

Donor lymphocyte infusions (DLIs) can induce complete and durable remissions in some patients with hematologic malignancies who have relapsed after allogeneic transplantation, providing definitive evidence of a GVL effect. Despite the great promise initially envisioned for DLI as a method to augment GVL after transplantation, it utility is limited by low response rates in diseases other than chronic myelogenous leukemia and by the development of GVHD, the principal complication of DLI. To maximize GVL potency while minimizing toxicity, cellular effectors active in GVL need to be elucidated. Insight into mechanisms of GVL, such as reversal of in situ T-cell exhaustion, may allow identification of patients who will respond to DLI based on the presence of tumor-infiltrating lymphocytes in the BM. Understanding the clinical factors that influence the effectiveness and abrogate the toxicity of DLI, such as cell dose and timing of DLI after transplantation, will allow further optimization of DLI. This chapter reviews novel strategies that maximize the GVL effect of DLI by enhancing activity while limiting toxicity.

Post-transplant T cell chimerism predicts graft versus host disease but not disease relapse in patients undergoing an alemtuzumab based reduced intensity conditioned allogeneic transplant

In this multicentre retrospective study we have studied the impact of T cell chimerism on the outcome of 133 patients undergoing an alemtuzumab based reduced intensity conditioning allograft (RIC). The median age of the patients was 50 years (range 42-55 years). 77 patients were transplanted using an HLA identical sibling donor while 56 patients received a fully matched volunteer unrelated donor graft. 64 patients had a lymphoid malignancy and 69 were transplanted for a myeloid malignancy. 38 patients (29%) relapsed with no significant difference in risk of relapse between patients developing full donor and mixed donor chimerism in the T-cell compartment on D+90 and D+180 post transplant. Day 90 full donor T cell chimerism correlated with an increased incidence of acute GVHD according to NIH criteria (p=0.0004) and the subsequent development of chronic GVHD. Consistent with previous observations, our results confirmed a correlation between the establishment of T cell full donor chimerism and acute GVHD in T deplete RIC allografts. However our study failed to identify any correlation between T cell chimerism and relapse risk and challenge the use of pre-emptive donor lymphocyte infusions (DLI) in patients with mixed T cell chimerism transplanted using an alemtuzumab based RIC regimen.

Outcome of donor lymphocyte infusion after T cell-depleted allogeneic hematopoietic stem cell transplantation for acute myelogenous leukemia and myelodysplastic syndromes

Relapse occurs in 30%-50% of recipients of T cell-depleted (TCD) reduced-intensity conditioned (RIC) hematopoietic stem cell transplantation (HSCT) for acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS). Despite limited published supportive data, donor lymphocyte infusion (DLI) is used preemptively (pDLI) to improve donor chimerism and prevent relapse, and therapeutically (tDLI) after disease recurrence. We evaluated the efficacy and toxicity of pDLI and tDLI in 113 patients after TCD (alemtuzumab, n = 99; antithymocyte globulin, n = 14) RIC HSCT for AML or MDS. Recipients of pDLI (n = 62) had an estimated 5-year overall survival (OS) of 80% and an event-free survival of 65%. More than one-half (52%; n = 32) of the patients received pDLI within 6 months post-HSCT; despite this, the 5-year incidence of graft-versus-host disease was only 31% (95% confidence interval [CI], 19%-43%). Recipients of tDLI (n = 51) had an estimated 5-year OS of 40% and a 5-year relapse/progression rate of 69% (95% CI, 54%-81%). Recipients of tDLI at >6 months post-HSCT had a significantly superior 5-year OS after tDLI compared with those treated earlier (P = .008). The cumulative incidence of graft-versus-host disease at 5 years after tDLI was 45% (95% CI, 23%-65%). We demonstrate that pDLI safely promotes durable remission after TCD RIC HSCT for AML or MDS, and that tDLI salvages patients after late relapse with greater efficacy.

Favorable outcomes in patients with high donor-derived T cell count after in vivo T cell-depleted reduced-intensity allogeneic stem cell transplantation

Patients with hematologic malignancies were conditioned using a rabbit antithymocyte globulin-based reduced-intensity conditioning regimen for allogeneic stem cell transplantation. Donor-derived CD3(+) cell count (ddCD3), a product of CD3(+) cell chimerism and absolute CD3(+) cell count, when <110/μL at 8 weeks post-stem cell transplantation predicted a high risk of sustained mixed chimerism and relapse. Alternatively, patients with a higher ddCD3 developed graft-versus-host disease more frequently, and when partially chimeric, had higher rates of conversion to full donor chimerism after withdrawal of immunosuppression. Early data from our small cohort of patients indicate that ddCD3 at 8 weeks may be used to guide decisions regarding withdrawal of immunosuppression and administration of donor lymphocyte infusion in partially T cell-depleted reduced-intensity regimens.

Phase I study of high-stringency CD8 depletion of donor leukocyte infusions after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Donor leukocyte infusions (DLI) are given after hematopoietic stem-cell transplantation to eradicate persistent tumor or correct mixed chimerism (MC). The drawback of DLI is the risk of graft-versus-host disease (GVHD). In this phase I study, we examined the potential of highly extensive CD8 depletion of DLI as a means of improving its safety profile.

METHODS

High-stringency immunomagnetic CD8 depletion of DLI was performed after steady state donor apheresis. Patients with persistent disease or MC received escalated dose CD8-depleted DLI at 3-month intervals starting from 6 months posttransplantation. The starting dose was 1 x 10(6) CD4 cells/kg in recipients of unrelated and 3 x 10(6) CD4 cells/kg in recipients of related donor transplantations.

RESULTS

Twenty-eight patients received CD8-depleted DLI (n=16 unrelated or mismatched, n=12 human leukocyte antigen-identical sibling). Median CD8 depletion was more than 4 log. The median overall dose of CD4+ cells/kg given was 4 x 10(6) (range 1 x 10(6)-43 x 10(6)). Conversion from MC to full donor chimerism was observed in 8 of 16 evaluable patients, and disease responses occurred in 5 of 11 patients (complete response in four and partial response in one). Five of 28 patients developed severe acute pattern (grade II-IV) GVHD. Two patients died as a result of complications relating to GVHD.

CONCLUSIONS

Graft-versus-tumor effects can be observed after high-stringency CD8-depleted DLI, although the major toxicity remains GVHD in this high-risk patient group. The safety and efficacy profile of this approach will require testing in a randomized controlled study.

Outcome of second allogeneic transplants using reduced-intensity conditioning following relapse of haematological malignancy after an initial allogeneic transplant

Disease relapse following an allogeneic transplant remains a major cause of treatment failure, often with a poor outcome. Second allogeneic transplant procedures have been associated with high TRM, especially with myeloablative conditioning. We hypothesized that the use of reduced-intensity conditioning (RIC) would decrease the TRM. We performed a retrospective national multicentre analysis of 71 patients receiving a second allogeneic transplant using RIC after disease relapse following an initial allogeneic transplant. The majority of patients had leukaemia/myelodysplasia (MDS) (N=57), nine had lymphoproliferative disorders, two had myeloma and three had myeloproliferative diseases. A total of 25% of patients had unrelated donors. The median follow-up was 906 days from the second allograft. The predicted overall survival (OS) and TRM at 2 years were 28 and 27%, respectively. TRM was significantly lower in those who relapsed late (>11 months) following the first transplant (2 years: 17 vs 38% in early relapses; P=0.03). Two factors were significantly associated with a better survival: late relapse (P=0.014) and chronic GVHD following the second transplant (P=0.014). These data support our hypothesis that the second RIC allograft results in a lower TRM than using MA. A proportion of patients achieved a sustained remission even when relapsing after a previous MA transplant.

Donor lymphocyte infusions: the long and winding road: how should it be traveled?

Donor lymphocyte infusions (DLI) often are used after allo-SCT to augment the graft-versus-tumor effect. Timing of infusion varies according to indication, for example to treat tumor recurrence, as a planned strategy to prevent disease relapse in the setting of T-cell-depleted grafts or non-myeloablative conditioning regimens, or as a method to convert mixed to full donor chimerism. The optimal strategy of timing, use of cytotoxic conditioning, cell dose and cell product composition, and so on, for DLI administration remains unclear. Despite varied techniques, DLI may lead to 3-year disease-free survivals (DFS) in excess of 60% for all CML patients and approach 90% in patients with only molecular or cytogenetic relapse. Other hematologic malignancies appear much less responsive, as less than 50% of patients respond and provide, at best, 3-year DFS rates of 20-50%. Multiple myeloma patients have overall response rates of 40-45% after DLI, suggesting benefit in relapsed disease, but limited experiences for diseases such as Hodgkin's lymphoma, myelodysplasia and ALL preclude recommendations for use of DLI at this time. Regardless of the indication, treatment-related mortality after DLI is 5-20% and more than one-third of patients will develop acute and/or chronic GVHD after DLI. The risks of these complications appear related, in part, to donor source, cell dose and therapy prior to DLI. Although there are no definitive answers, the information gleaned from published literature suggests that DLI should be administered early after relapse or as a prophylactic strategy in patients receiving T-cell-depleted grafts, and patients with bulky or aggressive disease may benefit from disease reduction prior to DLI.

Clinical outcomes of late rather than early full-donor chimerism in patients with advanced lymphomas receiving nonmyeloablative allogeneic hematopoietic SCT

Allogeneic hematopoietic SCT (HSCT) can ideally provide long-term remission in advanced lymphoma patients by capturing a graft-vs-tumor (GVT) effect. On the basis of a murine model, we attempted to optimize a GVT effect through nonmyeloablative therapy and HLA-matched related donor HSCT with intentional induction of mixed chimerism followed by prophylactic donor lymphocyte infusion. A total of 26 advanced lymphoma patients were separated into an early and late full-donor chimerism (FDC) group using a median of 45 days post-HSCT as the defining point for FDC. Upon generating these groups, analysis by Student's t-test demonstrated that they were statistically distinct in time to develop FDC (P<0.01). There was a trend toward improved CR rates in the late group relative to the early group (62 vs 31%; P=0.12). A trend toward improved progression-free survival at 5 years was also observed in the late compared to the early group by Kaplan-Meier analysis (38 vs 8%; P=0.081). However, this did not correlate to a significant overall survival benefit. In conclusion, these data support the observation from our mouse models that the most potent GVT effect occurs in mixed chimeras with late chimerism conversion.