Quantitative analysis of chimerism using a short tandem repeat method on a fluorescent automated DNA sequencer

Lost in translation? Microchimersim detection in experimental and clinical transplantation

The importance of further elucidating the properties surrounding microchimerism in various experi- mental models and clinical transplantation are limited by current techniques and the sensitivity of available platforms. Development of reliable methods and use routine use of microchimerism detection in clinical practice could guide clinical decision making regarding rejection, stable function, and tolerance.

Myeloablative intravenous pharmacokinetically targeted busulfan plus fludarabine as conditioning for allogeneic hematopoietic cell transplantation in patients with non-Hodgkin lymphoma

BACKGROUND

Mortality associated with allogeneic hematopoietic cell transplantation (allo-HCT) has limited its broader application in patients with non-Hodgkin lymphoma (NHL). Pharmacokinetic treatment with targeted intravenous busulfan combined with fludarabine (BuFlu) was developed as a preparative regimen for acute leukemia and myelodysplasia. Data from this regimen in lymphoid malignancies are limited.

PATIENTS AND METHODS

We assessed outcomes in 60 consecutive patients with various subtypes of NHL and a median age of 54 years (range, 27-68 years) who received allo-HCT with targeted intravenous BuFlu between December 2004 and August 2010. The median number of previous therapies was 3 (range, 1-8) and median time from diagnosis to HCT was 32 months (range, 4.5-177.5 months).

RESULTS

At conditioning, 28 (47%) patients had a complete response (CR). Graft versus host disease (GVHD) prophylaxis consisted of tacrolimus plus methotrexate in 65% of cases. Donors were matched/related (n = 32 [53%]), matched/unrelated (n = 21 [35%]), or mismatched/unrelated (n = 7 [12%]). All patients underwent grafting. The cumulative incidence of grade II/IV acute GVHD was 74% (grade III/IV was 20%). The 2-year cumulative incidence of moderate to severe chronic GVHD was 62%. Nonrelapse mortality (NRM) at 100 days and 3 years was 10% and 25%, respectively. The cumulative incidence of relapse was 27%. Three-year progression-free and overall survival for all patients was 47.8% and 55%, respectively.

CONCLUSION

Targeted intravenous BuFlu is a relatively well tolerated regimen and offers an alternative option when myeloablation is deemed necessary in patients with NHL.

Pharmacokinetically-targeted BU and fludarabine as conditioning before allogeneic hematopoietic cell transplantation for adults with ALL in first remission

Allogeneic hematopoietic cell transplantation offers improved survival in patients with ALL, but with regimens containing TBI, the nonrelapse mortality is 20-40%. Efforts to lessen transplant toxicities by reducing conditioning regimen intensity have led to increased relapse risk. Therefore, there is a need for less toxic regimens that maintain an anti-leukemia effect. We report here a retrospective review of 65 patients with ALL in first remission receiving grafts from allogeneic donors after fludarabine 40 mg/m(2)/day for 4 days and i.v. BU targeted to a median daily area under the concentration-time curve below 6000 μmoles min/L. At 2 years after transplantation, OS was 65% (95% confidence interval (CI): 52-77%), relapse-free survival was 61% (95% CI: 48-73%), cumulative incidence of relapse was 26% (95% CI: 17-39%) and cumulative incidence of nonrelapse mortality was 14% (95% CI: 8-26%). Age over 35 years, Ph chromosome positivity and minimal residual disease at transplant did not adversely affect outcomes. Pharmacokinetically targeted BU and fludarabine can provide intensive pre-transplant conditioning for adults with ALL in first remission, with promising relapse-free and OS rates.

Lineage-specific chimerism analysis in nucleated cells, T cells and natural killer cells after myeloablative allogeneic hematopoietic stem cell transplantation

Background

Chimerism analysis is an important tool for assessing the origin of hematopoietic cells after allogeneic stem cell transplantation (allo-SCT) and can be used to detect impending graft rejection and the recurrence of underlying malignant or nonmalignant diseases.

Methods

This study included 24 patients who underwent myeloablative allo-SCT. DNA was extracted from nucleated cells (NCs), T cells, and natural killer (NK) cells, and the chimerism status of these cell fractions was determined by STR-PCR performed using an automated fluorescent DNA analyzer.

Results

Twenty-three out of the 24 patients achieved engraftment. Mixed chimerism (MC) in NCs, but not in T cells and NK cells, was significantly correlated with disease relapse. MC in all cell fractions was correlated with mortality. Ten patients (41.6%) developed extensive chronic GVHD. Six patients had MC in T cells, and 3 of them had chronic GVHD. Four patients with MC and relapse received donor lymphocyte infusion (DLI), and among them, 3 had secondary relapse. Further, the chimerism status differed among different cell lineages in 6 patients with myeloid malignancies.

Conclusion

The implications of MC in lymphocyte subsets are an important area for future research. Chimerism analysis in lineage-specific cells permits detection of relapse and facilitates the monitoring of therapeutic interventions. These results can provide the basic data for chimerism analysis after myeloablative SCT.

Pharmacokinetic targeting of i.v. BU with fludarabine as conditioning before hematopoietic cell transplant: the effect of first-dose area under the concentration time curve on transplant-related outcomes

We used pharmacokinetic (PK) targeting of BU in 145 consecutive patients treated with fludarabine and i.v. BU. BU was given once daily at 130 mg/m(2) per day on days 1 and 2; doses for days 3 and 4 were adjusted in 92 patients (63%) to an average daily area under the concentration-time curve (AUC) of 5300 μM/min. In the remaining 53 patients, the first-dose AUC was within the target range and no dosing adjustments were required. First-dose AUC, maximum concentration and clearance were not correlated with age, race, ethnicity, performance status, or hematopoietic cell transplant comorbidity index. Women had higher clearance than men (median 2.9 vs 2.5 mL/min/kg; P=0.001). BU toxicities were not associated with first-dose AUC or any other PK parameter measured. First-dose BU AUC was not associated with non-relapse mortality (NRM) or survival, but higher AUC was predictive of relapse. We did not find an increased risk of toxicity or NRM in patients with high first-dose AUC presumably because of the dose adjustment. We conclude that PK targeting of BU as described here provides a simple, safe and effective method of delivering high BU doses before transplantation in a wide variety of patients.

Recent advances in quantitative chimerism analysis

Quantitative chimerism analysis is a diagnostic tool used to monitor engraftment kinetics after allogeneic stem cell transplantation. It reflects the proportion of recipient and donor genotypes and is based on the identification of genetic markers characteristic to a given transplant pair. Currently, PCR amplification of short tandem repeats and single-nucleotide polymorphism-specific quantitative real-time PCR are the most widely used techniques for this purpose. In this review, we will address advances as well as technology-specific imperfections, of both techniques that have emerged over the recent years. We will discuss new principles that may simplify assay design, and improve its robustness and reliability. A better chimerism assay could then guide clinical interventions and may, eventually, improve the outcome of allogeneic stem cell transplantation.

Clinical utility of chimerism status assessed by lineage-specific short tandem repeat analysis: experience from four cases of allogeneic stem cell transplantation

Chimerism testing permits early prediction and documentation of successful engraftment, and also facilitates detection of impending graft rejection. In this study, we serially monitored chimerism status by short tandem repeat-based PCR in nucleated cells (NC), T cells and natural killer (NK) cells after myeloablative allogeneic stem cell transplantation (SCT). Four patients with myeloid malignancies showed discrepant chimerism results among those three fractions. Three patients had mixed chimerism (MC) of donor/host T cells at a time point around the onset of chronic graft-versus-host disease (GVHD). In two patients with disease relapse, MC of NK cells preceded a morphological relapse or NK cells showed a higher percentage of patient cells compared to NC. Therefore, our study shows that chimerism analysis in lineage-specific cells might be useful in predicting clinical outcome after allogeneic SCT in certain patients.

Female genital tract graft-versus-host disease: incidence, risk factors and recommendations for management

Female genital tract graft-versus-host disease (GVHD) is an under-recognized complication of allogeneic stem cell transplantation impacting on quality of life. We describe a prospective surveillance programme for female genital GVHD to better characterize incidence, risk factors and clinical features and the impact of a structured intervention policy. A retrospective audit was conducted on the medical records of all female transplant recipients surviving at least 6 months at a single centre over a 5-year period. Patients commenced topical vaginal oestrogen early post transplant with hormone replacement as appropriate for age, prior menopausal status and co-morbidities. A genital tract management programme included regular gynaecological review and self-maintenance of vaginal capacity by dilator or intercourse. The incidence of genital GVHD was 35% (95% confidence interval (CI) (25, 50%)) at 1 year and 49% (95% CI (36, 63%)) at 2 years. Topical therapy was effective in most cases; no patient required surgical intervention to divide vaginal adhesions. The main risk factor was stem cell source with peripheral blood progenitor cells posing a higher risk than marrow (hazard ratio=3.07 (1.22, 7.73), P=0.017). Extensive GVHD in other organs was a common association. We conclude that female genital GVHD is common, and early detection and commencement of topical immunosuppression with dilator use appears to be highly effective at preventing progression.