Salvage chemotherapy in relapsed germ cell tumors

Issues concerning the optimal salvage treatment in patients with germ cell tumors are for the most part controversial. As the majority of patients will suffer systemic relapses, chemotherapy will remain the mainstay of any salvage treatment. However, the question of whether to use conventional-dose or high-dose chemotherapy (HDCT) immediately arises. Prognostic factors have recently been recognized as an aid in this decision. However, as reliable data are lacking for many clinical scenarios, the salvage treatment of germ-cell tumors continues to be a therapeutic challenge.

Quantitative detection of Toxoplasma gondii DNA in human body fluids by TaqMan polymerase chain reaction

OBJECTIVE

A new quantitative polymerase chain reaction (real-time PCR) was designed to detect Toxoplasma DNA in human body fluid samples.

METHODS

Real-time fluorescence detection of amplification product formation on the basis of the TaqMan-System was established with Toxoplasma 18S rDNA as a target gene.

RESULTS

The method provides a high sensitivity comparable to conventional nested PCR procedures and generates quantitative data when detecting toxoplasmic DNA in human blood, cerebrospinal or amniotic fluid. Moreover, data were obtained investigating blood samples from an immunocompromised patient with reactivated toxoplasmosis after allogeneic bone marrow transplantation, monitoring the therapeutic effect.

CONCLUSIONS

The potential application of this method to detect Toxoplasma DNA in body fluids and to follow the development of parasitemia under therapy could be demonstrated.

PBPC mobilization with paclitaxel, ifosfamide, and G-CSF with or without amifostine: results of a prospective randomized trial

BACKGROUND

The impact of amifostine on PBPC mobilization with paclitaxel and ifosfamide plus G-CSF was assessed.

STUDY DESIGN AND METHODS

Forty patients with a median age of 34 years (range, 19-53) who had germ cell tumor were evaluated for high-dose chemotherapy. Patients were randomly assigned to receive either a single 500-mg dose of amifostine (Group A, n = 20) or no amifostine (Group B, n = 20) before mobilization chemotherapy with paclitaxel (175 mg/m(2)) given over 3 hours and ifosfamide (5 g/m(2)) given over 24 hours (TI) on Day 1. G-CSF at 10 microg per kg per day was given subsequent to TI with or without amifostine from Day 3 until the end of leukapheresis procedures.

RESULTS

In 2 (10%) of 20 patients receiving amifostine and 3 (15%) of 20 patients not receiving it, no PBPC separation was performed because of mobilization failure. No significant differences were observed in the study arms with regard to the time from chemotherapy until first PBPC collection or the number of apheresis procedures needed to harvest more than 2.5 x 10(6) CD34+ cells per kg. Furthermore, leukapheresis procedures yielded comparable doses of CD34+ cells per kg (3.4 x 10(6) vs. 3.6 x 10(6); p = 0.82), MNCs per kg (2.7 x 10(8) vs. 2.6 x 10(8); p = 0.18), and CFU-GM per kg (15.9 x 10(4) vs. 19.3 x 10(4); p = 0.20). Patients in Group A had higher numbers of circulating CD34+ cells on Day 10 (103.0/microL vs. 46.8/microL; p = 0.10) and on Day 11 (63.0/microL vs.14.3/microL; p = 0.04) than did patients in Group B.

CONCLUSION

Administration of a single dose of amifostine before chemotherapy with TI mobilized higher numbers of CD34 cells in the circulation, but did not enhance the overall collection efficiency in the present trial.

Four patients with AL amyloidosis treated with high-dose chemotherapy and autologous stem cell transplantation

Four patients with AL amyloidosis underwent high-dose chemotherapy and autologous stem cell transplantation at our institutions. Here, we report the clinical courses and outcomes in these patients. Two patients with multi-organ amyloid deposits including cardiac involvement died within 12 days after high-dose chemotherapy. However, in the other two patients, one of whom was suffering from amyloid-related cardiac failure, a significant improvement of organ function was achieved.

Human herpesvirus 6A DNA Is detected frequently in plasma but rarely in peripheral blood leukocytes of patients after bone marrow transplantation

A real-time quantitative polymerase chain reaction assay was devised to determine the load of human herpesvirus (HHV)-6A and -6B DNA in paired samples of plasma and peripheral blood leukocytes (PBL) of 25 bone marrow transplant patients. The assay detects HHV-6 DNA variants A and B in a linear range of 10(7)-10(1) genome equivalents per assay. Viral DNA was measured in 336 paired DNA PBL samples and in corresponding plasma samples. HHV-6A and/or -6B DNA was detected in PBL of 23 of 25 patients and in plasma of 24 of 25 patients. HHV-6B was the predominant variant found in PBL and also was detected in the corresponding plasma. Surprisingly, only 1 of 25 patients had detectable HHV-6A DNA in PBL, although 23 of 25 patients were positive for HHV-6A DNA in plasma. HHV-6 DNA load in plasma was significantly higher for HHV-6A than for HHV-6B (P=.0066).

Salvage treatment with paclitaxel, ifosfamide, and cisplatin plus high-dose carboplatin, etoposide, and thiotepa followed by autologous stem-cell rescue in patients with relapsed or refractory germ cell cancer

PURPOSE

To study feasibility and efficacy of a new salvage regimen in patients with relapsed and/or refractory germ cell tumors.

PATIENTS AND METHODS

Between May 1995 and February 1997, 80 patients were entered onto a phase II study. Conventional-dose salvage treatment with three cycles of paclitaxel 175 mg/m(2), ifosfamide 5 x 1.2 g/m(2), and cisplatin 5 x 20 mg/m(2) (TIP) was followed by one cycle of high-dose chemotherapy (HDCT) with carboplatin 500 mg/m(2) x 3, etoposide 600 mg/m(2) x 4, and thiotepa 150 to 250 mg/m(2) x 3 (CET). In 23 patients, one additional cycle of paclitaxel 175 mg/m(2) and ifosfamide 5 g/m(2) (TI) was given immediately before TIP to improve stem-cell mobilization.

RESULTS

Fifty-five (69%) of 80 patients responded to TIP, 24 (30%) of 80 patients had stable disease (n = 5) or tumor progression (n = 19), and one patient died. Only 62 (78%) of 80 patients received subsequent HDCT. Among those, 41 (66%) of 62 patients responded and 20 (32%) of 62 patients had stable disease (n = 3) or tumor progression (n = 17). One patient died after HDCT from multiorgan failure. Survival probabilities at 3 years were 30% for overall and 25% for event-free survival. Peripheral neurotoxicity with sensorimotor impairment grade 2 through 4 in 29%, paresthesias grade 2 through 4 in 24%, and skin toxicity grade 2 through 3 in 15% of patients were the most relevant side effects.

CONCLUSION

Treatment with TIP followed by high-dose CET is feasible and can induce long-term remissions in 25% of patients with relapsed or refractory germ cell tumors. Peripheral nervous toxicity in approximately one third of patients is a disadvantage of this salvage strategy.

Detection of germ-cell tumor cells in peripheral blood progenitor cell harvests: impact on clinical outcome

Our study was conducted to evaluate the impact of tumor cell contamination in peripheral blood progenitor cell (PBPC) harvests on the clinical outcome of patients with germ-cell tumors undergoing high-dose chemotherapy (HDCT) and autologous PBPC reinfusion. Samples of mononuclear cells from progenitor cell harvests of 57 patients with advanced or recurrent germ-cell tumors were retrospectively screened for contaminating tumor cells using immunocytochemical staining for cytokeratin filaments and reverse transcription-PCR (RT-PCR) testing for germ-cell alkaline phosphatase mRNA. The results were correlated to clinical prognostic variables as well as to the overall and event-free survival of these patients. Tumor cell contamination was detected in PBPC harvests of 16 of 57 enrolled patients (28%), and, among these, in 14 of 51 (27%) who underwent HDCT. The presence of contaminating tumor cells as detected by either immunocytochemical staining, RT-PCR, or both was strongly associated with a reduced overall survival (43% versus 71%, P = 0.0037) and event-free survival (0% versus 52%, P = 0.0005) after 1 year. In multivariate analysis, the demonstration of contaminating tumor cells had a higher predictive value for a poor event-free survival than other known prognostic variables. The presence of contaminating tumor cells in PBPC harvests of patients with germ-cell tumors seems to predict a poor overall and event-free survival in patients undergoing HDCT and autologous PBPC reinfusion.

Successful autologous bone marrow rescue in patients who failed peripheral blood stem cell mobilization

We assessed autologous bone marrow (BM) harvest and hematologic recovery after high-dose chemotherapy (HDCT) in patients who failed to achieve peripheral blood stem cell (PBSC) mobilization. One hundred and ninety-three patients with germ cell tumor, malignant lymphoma, sarcoma or medulloblastoma were scheduled for HDCT. In 123 patients, PBSC were mobilized by disease-specific chemotherapy plus granulocyte colony-stimulating factor (G-CSF). In 110/ 123 patients (89%) with circulating CD34+ cell counts 2 > or = 10/microl, sufficient hematopoietic autografts were collected (group A). In 13/123 patients (11%) with peripheral CD34 + cell counts < 10/microl, PBSC harvesting was not performed (group B). These latter patients were classified as "poor mobilizers" and underwent second-line BM harvest at a median of 46 (range 10-99) days after mobilization failure. Seventy patients with first-line BM harvest (group C) acted as historical controls. Ten patients from group B proceeded to HDCT and nine were evaluable for hematopoietic reconstitution. Recovery to neutrophils >0.5 x 10(9)/l was comparable with group C patients: 16 (range 9-34) days vs 13 (range 8-98) days. However, platelet (PLT) reconstitution >20 x 10(9)/l was significantly slower, with a median of 35 (range 13-50) days as compared with 19 (range 9-148) days (P = 0.0106) for control patients. Supportive care requirements, febrile days and length of hospital stay were not significantly different between the two groups of patients. We conclude that patients who fail to mobilize PBSC should be evaluated for second-line BM harvest. This approach may preserve the therapeutic option of HDCT for these patients.

Presence of human beta- and gamma-herpes virus DNA in Hodgkin's disease

Herpes viruses have been implicated in the etiology of Hodgkin's disease (HD). We studied the prevalence of human cytomegalovirus (CMV), human herpes viruses type-6 (HHV-6), type-7 (HHV-7) and type 8 (HHV-8) DNA in up to 88 Hodgkin's disease biopsies in comparison to Epstein-Barr virus (EBV) DNA by polymerase chain reaction (PCR). Non-Hodgkin lymphomas (NHL) and reactive lesions served as controls. CMV and HHV-6 were found in 8/86 (9%) and 11/88 (13%) HD cases, respectively, by nested primer PCR. Except for three cases harbouring HHV-6 type-B, only HHV-6 type-A was detected in HD. HHV-7 was observed by nested PCR in 33/88 (38%) HD cases and was already detectable in 15/88 (17%) HD cases by a single-round PCR indicating elevated virus copy numbers. Seven of these cases showed co-infection with HHV-6, and 11 cases were found to contain EBV DNA. 7/8 CMV-positive HD cases also harboured EBV DNA. HHV-8 DNA was not detected by single round or nested PCR in any HD case investigated. Thus, CMV, HHV-6, and HHV-7 were present in small proportions of HD cases, with frequent co-infection of HHV-6 and HHV-7, and frequent association with EBV. In contrast to EBV, beta-herpes viruses are therefore unlikely to have a role in the aetiology of HD. Rather, the presence of these viruses seems to reflect impaired immunological surveillance.

Rapid quantification and differentiation of human polyomavirus DNA in undiluted urine from patients after bone marrow transplantation

A combined PCR assay was developed for the detection and typing of human polyomavirus (huPoV) in clinical samples, consisting of (i) a qualitative seminested PCR assay (snPCR) to discriminate between huPoV BK and JC and (ii) a high-throughput, quantitative TaqMan PCR assay (TM-PCR) for the general detection of huPoV. The TM-PCR detects huPoV DNA in a linear range from 10(7) to 10(1) copies per assay. In reproducibility runs, the inter- and intra-assay variabilities were < or =60 and < or =50%, respectively. The snPCR assay uses a set of four primers for the same region of the BK and JC viral genomes. In the first round of amplification, two general primers were used; in the second round, one of these general primers and two additional, BK- or JC-specific primers were used simultaneously to produce amplicons of different sizes specific for BK virus (246 bp) and JC virus (199 bp), respectively. We tested different urine dilutions in order to determine the inhibitory effects of urine on PCR amplification. Furthermore, we compared the use of native urine with DNA purified by different preparation procedures. Our results show, that a 1:10 dilution of the urine led to complete reduction of the amplification inhibition found with 6% of undiluted urine samples. In a clinical study including 600 urine specimens, our assay turned out to be fast, cheap, and reliable in both qualitative and quantitative aspects.

Treatment of BK virus-associated hemorrhagic cystitis and simultaneous CMV reactivation with cidofovir

Hemorrhagic cystitis (HC) is a common complication following high-dose chemotherapy and bone marrow transplantation, and the treatment of virus-associated HC remains to be optimized. This is the first report on the successful use of cidofovir in a patient with HC and polyoma viruria concomitant with CMV reactivation after allogeneic BMT. Treatment led to a significant decrease in viruria and to sustained suppression of CMV reactivation. Administered with probenecid and hydration, cidofovir was well tolerated, and there were no side-effects.

Detection of human cytomegalovirus DNA by real-time quantitative PCR

A real-time PCR assay was developed to quantify human cytomegalovirus (CMV) DNA. This assay was used to demonstrate a higher CMV DNA load in plasma of bone marrow transplant patients than in that of blood donors. The CMV load was higher in CMV antigen-positive patients than in antigen-negative patients.

Applicability of an absolute quantitative procedure to monitor intra-individual bcr/abl transcript kinetics in clinical samples from chronic myelogenous leukemia patients

Chimeric bcr/abl fusion proteins are thought to be the molecular 'pathogen' of chronic myelogenous leukaemia (CML). Expression levels of the respective fusion RNAs reflect disease progression as well as remission upon therapeutic intervention in CML patients. However, there is no quick and reliable method that would allow the quantitative routine monitoring of bcr/abl hybrid transcripts. A fluorescent probe-based PCR assay (TaqMan) has been described to quantitfy the exact amount of target sequences. We have established TaqMan real-time RT-PCRs for M-bcr/abl (b2a2, b2a3, b3a2, b3a3) and m-bcr/abl (e1a2) fusion transcripts as well as for beta-actin. All PCRs quantified as little as 10 copies/100 ng total cDNA. In order to investigate whether this procedure is appropriate for routine diagnostic monitoring, we performed retrospective measurements on 9 documented CML disease courses. Our data show that ongoing or relapsing CML is paralleled by increasing peripheral levels of bcr/abl fusion RNAs. Furthermore, sucessful anti-leukemic treatment is reflected by decreasing absolute bcr/abl transcript numbers. In contrast with conventional bcr/abl PCR techniques we could distinguish single positive values and gradually increasing copy numbers.

Diagnosis of toxoplasmosis in bone marrow transplant recipients: comparison of PCR-based results and immunohistochemistry

Toxoplasmosis in bone marrow transplant recipients is a rare but serious complication and if untreated, almost uniformly fatal. The diagnosis, however, remains difficult. We therefore compared serial determination of antibody titers specific for T. gondii before and after transplantation, serial PCR for T. gondii DNA in serum, PCR and nested PCR for T. gondii DNA in various tissues, conventional histology and immunohistochemistry for detection of parasites in three patients with autopsy-confirmed toxoplasmosis after bone marrow transplantation. Immunohistochemistry demonstrated the presence of parasites in 13 out of 20 organs investigated (65%), whereas PCR detected T. gondii-specific DNA in 15 out of 20 organs (75%). Immunohistochemistry revealed concordant results to PCR data in 60% of the specimens. With the use of a nested PCR protocol, eight out of nine samples (89%) were positive for T. gondii-specific DNA. The combination of both methods detected the presence of parasites in 90% of the specimens. Serial PCR in serum did not yield positive results. Neither PCR nor immunohistochemistry was able to detect parasites in all organs investigated, but both methods together improved sensitivity to 90% and consequently, should be used jointly to maximize diagnostic precision. Bone Marrow Transplantation (2000) 25, 1257-1262.

High-dose salvage chemotherapy. Germ-cell tumor treatment results in Germany

During the past 10 years, high-dose chemotherapy (HDCT) has emerged as a feasible and curative treatment option for patients with multiply relapsed and/or refractory germ-cell tumors. Increasing experience and the results from clinical trials have helped to optimize the application of HDCT and to define its role in the salvage concepts for germ-cell tumors.

Determination of platinum complexes in clinical samples by a rapid flameless atomic absorption spectrometry assay

The frequent use of platinum (Pt) complexes in cancer chemotherapy and the application of new therapeutic options and dosing strategies have increased the need for rapid analytic procedures to determine Pt concentrations in the biologic fluids of patients. Therefore a flameless atomic absorption spectrometry method for the quantification of Pt in plasma and ultrafiltrate was developed and validated. A simple sample preparation of only one dilution step was established. Only 400 microL of whole blood was required for duplicate analysis of Pt in both matrices. The matrix-specific temperature programs took less than 75 seconds. The lower limit of quantification was 40 ng Pt/mL and 20 ng Pt/mL for plasma and ultrafiltrate, respectively. Suitable linearity could be reached using separate calibration curves for the high and low Pt concentration ranges. Recovery of Pt was complete, and there were no major stability problems. The accuracy and precision of the new method met the international criteria for the validation of bioanalytic methods. In addition, the use of different anticoagulants for clinical sampling, ultrafiltration systems, and ultrafiltration conditions were investigated. The assay has already been extensively applied to pharmacokinetic studies. In conclusion, the new Pt assay proved to be rapid, simple, sensitive, and suitable for clinical use.

Interferon-alpha before allogeneic bone marrow transplantation in chronic myelogenous leukemia does not affect outcome adversely, provided it is discontinued at least 90 days before the procedure

The influence of interferon-alpha (IFN) pretreatment on the outcome after allogeneic bone marrow transplantation (BMT) in chronic myelogenous leukemia (CML) is controversial. One goal of the German randomized CML Studies I and II, which compare IFN +/- chemotherapy versus chemotherapy alone, was the analysis of whether treatment with IFN as compared to chemotherapy had an influence on the outcome after BMT. One hundred ninety-seven (23%) of 856 Ph/bcr-abl-positive CML patients were transplanted. One hundred fifty-two patients transplanted in first chronic phase were analyzed: 86 had received IFN, 46 hydroxyurea, and 20 busulfan. Forty-eight patients (32%) had received transplants from unrelated donors. Median observation time after BMT was 4.7 (0.7 to 13.5) years. IFN and chemotherapy cohorts were compared with regard to transplantation risks, duration of treatments, interval from discontinuation of pretransplant treatment to BMT, conditioning therapy, graft-versus-host disease prophylaxis and risk profiles at diagnosis and transplantation, and IFN cohorts also with regard to performance and resistance to IFN. Outcome of patients receiving related or unrelated transplants pretreated with IFN, hydroxyurea, or busulfan was not significantly different. Five-year survival after transplantation was 58% for all patients (57% for IFN, 60% for hydroxyurea and busulfan patients). The outcome within the IFN group was not different by duration of prior IFN therapy more or less than 5 months, 1 year, or 2 years. In contrast, a different impact was observed in IFN-pretreated patients depending on the time of discontinuation of IFN before transplantation. Five-year survival was 46% for the 50 patients who received IFN within the last 90 days before BMT and 71% for the 36 patients who did not (P =.0057). Total IFN dosage had no impact on survival after BMT. We conclude that outcome after BMT is not compromised by pretreatment with IFN if it is discontinued at least 3 months before transplantation. Clear candidates for early transplantation should not be pretreated with IFN.

Different real-time PCR formats compared for the quantitative detection of human cytomegalovirus DNA

BACKGROUND

The aim of this study was to compare the ABI PRISM 7700 Sequence Detection System and the LightCycler to develop a quantitative real-time PCR assay for the detection of human cytomegalovirus (HCMV) DNA suitable for routine hospital application.

METHODS

We used one exonuclease probe and five different hybridization probe sets as sequence-specific fluorescence detection formats. For the exonuclease assay and two hybridization probe sets, reproducibility and the detection limit were determined. To keep the total assay time to a minimum, we gradually shortened individual reaction steps on both instruments.

RESULTS

The exonuclease assay can be interchangeably performed on the 7700 and the LightCycler. No change of reaction conditions is required, except for the addition of bovine serum albumin to the LightCycler reaction. The shortest possible total assay time is 80 min for the ABI PRISM 7700 Sequence Detection System and 20 min for the LightCycler. When the LightCycler is used, the exonuclease probe can be replaced by a set of hybridization probes. All assays presented here detected HCMV DNA in a linear range from 10(1) to 10(7) HCMV genome equivalents/assay (r >0.995) with low intraassay (<5%) and interassay (<10%) variation.

CONCLUSIONS

The ABI PRISM 7700 Sequence Detection System as well as the LightCycler are useful instruments for rapid and precise online PCR detection. Moreover, the two principles of fluorescence signal production allow HCMV quantification with the same accuracy.

Aerosolized amphotericin B inhalations as prophylaxis of invasive aspergillus infections during prolonged neutropenia: results of a prospective randomized multicenter trial

We performed a prospective, randomized, multicenter trial to evaluate the effectiveness of prophylactic inhalations with aerosolized amphotericin B (aeroAmB) to reduce the incidence of invasive aspergillus (IA) infections in patients after chemotherapy or autologous bone marrow transplantation and an expected duration of neutropenia of at least 10 days. From March 1993 until April 1996, 382 patients with leukemias, relapsed high-grade non-Hodgkin lymphomas, or solid tumors were randomized with a 13:10 ratio to receive either prophylactic aeroAmB inhalations at a dose of 10 mg twice daily or no inhalation prophylaxis in an unblinded fashion. The incidence of proven, probable, or possible IA infections was 10 of 227 (4%) in patients who received prophylactic aeroAmB. This did not differ significantly from the 11 of 155 (7%) incidence in patients who received no inhalation prophylaxis (P =.37). Moreover, no differences in the overall mortality (13% v 10%; P =.37) or in the infection-related mortality (8% v 7%; P =.79) were found. In contrast to other nonrandomized trials, we observed no benefit from prophylactic aeroAmB inhalations, but the overall incidence of IA infections was low.

Identification of human cytomegalovirus variants by analysis of single strand conformation polymorphism and DNA sequencing of the envelope glycoprotein B gene region-distribution frequency in liver transplant recipients

Single strand conformation polymorphism analysis (SSCP) of PCR-amplified DNA and subsequent DNA sequencing of human cytomegalovirus (HCMV) glycoprotein B (gB) gene were applied to identify known HCMV strains and to detect new virus variants. 61 HCMV PCR positive patients were studied out of a cohort of 410 patients after liver transplantation (LTX). SSCP was able to distinguish between strains Davis, AD169, and Towne, and in addition could identify five new virus variants (Berlin B, C, E, F, and H). Their frequency, gB and gH types were determined. Simultaneous infections with two or three strains or variants, as well as a switch from one virus to another virus were observed during long-term follow-up. No correlation between the occurrence of certain virus strains or gB types and defined clinical manifestations of HCMV infection after LTX was drawn.

Candida dubliniensis candidemia in patients with chemotherapy-induced neutropenia and bone marrow transplantation

The recently described species Candida dubliniensis has been recovered primarily from superficial oral candidiasis in HIV-infected patients. No clinically documented invasive infections were reported until now in this patient group or in other immunocompromised patients. We report three cases of candidemia due to this newly emerging Candida species in HIV-negative patients with chemotherapy-induced immunosuppression and bone marrow transplantation.

Kinetics of the graft-versus-leukemia response after donor leukocyte infusions for relapsed chronic myeloid leukemia after allogeneic bone marrow transplantation

Little is known about the mechanisms and the kinetics of the so-called graft-versus-leukemia (GVL) response induced by donor lymphocyte infusions (DLI) in patients with leukemic relapse after allogeneic bone marrow transplantation (BMT). We sought to elucidate this problem by sequentially studying three patients with relapsed chronic myeloid leukemia after sex-mismatched BMT from time before donor leukocyte infusion until achievement of complete molecular remission. Lineage-specific chimerism was assessed longitudinally by a combined fluorescent immunophenotyping and sex chromosome-specific in situ hybridization approach. Results were related to quantitative detection of bcr-abl transcripts by competitive differential reverse transcriptase-polymerase chain reaction (RT-PCR), qualitative bcr-abl RT-PCR, and multiplex PCR-based DNA donor/recipient chimerism. All patients had predominant donor lymphopoiesis at the time of DLI, suggesting a state of tolerance to recipient leukemic and/or normal cells. In contrast, granulopoiesis and erythropoiesis were mainly recipient derived in both patients with hematologic relapse and partly recipient derived in the patient with molecular relapse. Eighty percent, 90%, and 8% of CD34(+) cells, respectively, were found to be of recipient origin at relapse, and few donor stem cells predicted for cytopenia post-DLI. Responses were seen after a time lag of 5 to 13 weeks after DLI and resulted in reversal to full donor chimerism within a critical switch period of 4 to 5 weeks. A sudden decrease in recipient cells was paralleled by a sharp decrease in bcr-abl transcript numbers detectable several weeks before achievement of molecular remission and onset of clinical graft-versus-host disease (GVHD). This response pattern was confirmed by retrospective RT-PCR analysis in an additional five patients. Prospective monitoring of stem cell chimerism and response may enable us to individually tailor adoptive immunotherapy in the future.