Effects of mixed chimerism and immune modulation on GVHD, disease recurrence and survival after HLA-identical marrow transplantation for hematologic malignancies

Evaluation of chimerism by quantitative PCR analysis of DNA polymorphism after allogeneic hematopoietic stem cell transplantation in a pediatric population with malignancies

Relapse remains the major pitfall to success for Allo-HSCT in children with malignancies. Ninety-one patients undergoing Allo-HSCT were retrospectively reviewed. Chimerism status was evaluated at days +30, +60, and +100 in PB. VNTR-PCR and STR-PCR were used for this purpose. Thirty-one patients recurred (34%) and none survived. Thirty-two remain alive in CR (35%). Patients who achieved a CC at those days had a significant higher RFS and OS than patients who did not. Twelve patients showing PMC had an increased risk of recurrence (p=0.02. OR 7.7). In the univariate analysis, the probability of death was higher in patients who were not in first CR before transplant (p=0.008.OR 2.09) and in those receiving cells not from PB (p=0.002.OR 2.03). In the multivariate analysis, the absence of CC at day +100 was associated with a higher probability of relapse (p=0.004. OR 10.8) and death (p=0.016. OR 9.3). Serial chimerism PCR-based analyses of polymorphic DNA markers can predict relapse. Patients with PMC are at the highest risk of recurrence. Patients receiving an Allo-HSCT in first CR from PB who achieve a CC at day +100 have a better outcome.

Peripheral dendritic cell chimerism in allogeneic hematopoietic stem cell recipients

BACKGROUND

Relapse and graft-versus-host disease (GVHD) represent major causes of morbidity and mortality following allogeneic hematopoietic stem cell transplantation (HSCT). Although leukocyte and T-cell chimerism analyses are performed routinely suggesting a predictive value on the patients outcome, little is known about chimerism of dendritic cells (DC) representing strong initiators of immune responses.

METHODS

In this prospective study, peripheral DC1 (CD11c+) and DC2 (CD123+) chimerism was determined in hematopoetic stem cell recipients. DCs were isolated from peripheral blood by fluorescence activated cell sorting. Chimerism analyses were performed by fluorescent in situ hybridization or by polymerase chain reaction-based typing of short tandem repeats.

RESULTS

At time of engraftment, DC chimerism analyses showed complete chimerism in 76.3% (DC1)/79.5% (DC2), mixed chimerism (MC) in 21.0% (DC1)/17.9% (DC2) and no chimerism in 2.7% (DC1)/2.6% (DC2) of the patients. Peripheral DC chimerism had no significant effect on relapse-free or overall survival. Although acute GVHD was observed more often in patients with MC for DC1/DC2 and chronic GVHD occurred more often in patients with MC for DC2, there was no statistically significant correlation.

CONCLUSIONS

Although DCs as antigen presenting cells are supposed to have an impact on the induction of GVHD, there was no significant correlation between incidence of GVHD and DC chimerism after HSCT.

Significance of chimerism in hematopoietic stem cell transplantation: new variations on an old theme

The main goal of post-transplantation monitoring in hematopoietic stem cell transplantation (HSCT) is to predict negative events, such as disease relapse, graft rejection and graft-versus-host disease, in order to intervene with appropriate therapy. In this context, chimerism analysis is an important method in monitoring post HSCT outcome. Mixed chimerism (MC) is mainly evaluated to define engraftment and relapse. Detection of MC is a prerequisite in both myeloablative and nonmyeloablative HSCT, in order to assess the graft status and decide later therapeutic strategies such as donor lymphocyte infusion. In this review, we discuss various techniques including erythrocyte phenotyping, cytogenetic analysis, fluorescent in situ hybridization, restriction fragment length polymorphism, STR/VNTR analysis and real-time quantitative PCR, along with the various methods used to detect minimal residual disease (MRD) in different diseases such as chronic myeloid leukemia, acute myelomonocytic leukemia or acute lymphoblastic leukemia. The review mainly highlights the optimal methodological approach, which needs to be informative, sensitive and quantitatively accurate for MC detection. Future of post HSCT graft monitoring lies in the selection of the most accurate and sensitive technique to determine both MC and MRD. Such an approach would be helpful in not only determining relapse or rejection, but also in ascertaining various responses to different treatment modalities.

Rapid induction of complete donor chimerism by the use of a reduced-intensity conditioning regimen composed of fludarabine and melphalan in allogeneic stem cell transplantation for metastatic solid tumors

We evaluated the feasibility and efficacy of a reduced-intensity conditioning (RIC) regimen of fludarabine and melphalan to achieve rapid complete donor chimerism after allogeneic stem cell transplantation (SCT) in patients with metastatic solid tumors. Between January 1999 and January 2003, 8 patients with metastatic breast cancer (BC) and 15 with metastatic renal cell carcinoma (RCC) underwent allogeneic SCT after an RIC regimen of 5 days of fludarabine and 2 days of melphalan. Filgrastim-mobilized stem cells from HLA-identical related or unrelated donors were infused. Prophylaxis for graft-versus-host disease (GVHD) consisted of tacrolimus and methotrexate. All 22 evaluable patients had 100% donor chimerism at day 30 and at all measurement times thereafter. One patient died 19 days after SCT. Nine patients (39%) had grades II to IV acute GVHD and 10 patients (43%) had chronic GVHD. Five patients (22%) died of nonrelapse treatment-related complications. Treatment-related disease response was seen in 10 patients (45%), with 3 complete responses, 2 partial responses, and 5 minor responses. Fludarabine-melphalan is a feasible and effective RIC regimen for allogeneic SCT in metastatic BC and RCC. It induces rapid complete donor chimerism without the need for donor lymphocyte infusion. Tumor regression associated with GVHD is consistent with graft-versus-tumor effect.