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R H Collins

Publications and source records attributed to R H Collins.

At least 19 recordsLinked to original sources
PubMed2005

The graft-versus-lymphoma effect: clinical review and future opportunities.

Numerous lines of preclinical and clinical evidence support the existence of a graft-versus-leukemia effect, but less evidence supporting a comparable graft-versus-lymphoma effect exists. We review here current clinical data addressing the graft-versus-lymphoma effect, including comparisons of autologous, syngeneic, and allogeneic transplantation; responses to immunomodulation; and responses to nonmyeloablative stem cell transplantation. Despite several limitations of the data, we believe that there is sufficient evidence suggesting a significant graft-versus-lymphoma effect. In addition, we discuss approaches for clinical management of lymphoma patients, opportunities for mechanistic studies afforded by donor leukocyte infusions and nonmyeloablative transplantation, and suggestions for clinical studies to further define the magnitude and applicability of the graft-versus-lymphoma effect.

Graft vs Tumor Effect↗
PubMed2003

Definitive separation of graft-versus-leukemia- and graft-versus-host-specific CD4+ T cells by virtue of their receptor beta loci sequences.

Although graft-versus-host (GVH) disease (GVHD) is usually associated with graft versus leukemia (GVL), GVL can occur in the absence of clinical GVHD. There is evidence to suggest that GVL and GVH are mediated by different clones of T cells. The objective of this study was to identify the two types of T cells based on their receptor sequences. To this end we used irradiated nonleukemic cells from recipients as stimulator cells in a primary mixed leukocyte reaction (MLR). The activated CD4(+) donor T cells that expressed CD25 were purified by cell sorting. To prepare GVL-specific T cells, alloreactive T cells in the primary MLR were first depleted with an anti-CD25 immunotoxin. The remaining T cells had negligible alloreactivity in a secondary MLR. The allodepleted cells were then stimulated by using purified leukemia cells from the same individual as stimulator cells, and the CD25(+)-activated cells were purified by cell sorting. The GVL- and GVH-specific T cells were analyzed for their T cell receptor (TCR) clonality by using anchored RT-PCR of all the TCRbeta locus complementarity-determining region 3 (CDR3) sequences. By comparing TCRbeta CDR3 sequences from transformed bacterial colonies, we were able to demonstrate that T cells mediating GVH were different from those mediating GVL in each of the eight HLA-mismatched and one HLA-matched donor/recipient pairs. By using the appropriate TCRbeta CDR3-specific primers and probes, the GVH- and GVL-specific clones were monitored in a recipient undergoing an allogeneic stem cell transplant from her HLA-matched related donor.

CD4-Positive T-Lymphocytes↗
PubMed2003

Clinical-scale selective depletion of alloreactive T cells using an anti-CD25 immunotoxin.

Allogeneic hematopoietic stem cell transplantation is the treatment of choice for many hematological malignancies. Its efficacy is limited by graft-versus-host disease (GVHD), the leading cause of post-transplant morbidity and mortality. GVHD is mediated by a subpopulation of T cells in the stem cell graft. Ex vivo T cell depletion of all T cells of the graft can prevent development of GVHD but can lead to a delay in immune reconstitution and an increase of potentially lethal opportunistic infections and leukemic relapses. Hypothetically, an approach that enables a selective depletion of the alloreactive donor T cells that cause GVHD while preserving third party (anti-leukemic and anti-microbial) reactivity would be optimal for recipients of HSCT. Our preliminary data demonstrated that an anti-CD25 immunotoxin, which reacts with a cell surface activation antigen, can selectively deplete alloreactive donor T cells activated by non-leukemic recipient white blood cells while preserving the beneficial third-party reactivity in vitro. In this report we describe a method for clinical-scale ex vivo selective depletion of alloreactive donor T cells using the anti-CD25 immunotoxin, RFT5-SMPT-dgRTA. Two logs of alloreactive T cells could be selectively depleted while preserving third party reactivity. This method was reproducible in 10 pre-clinical experiments with 8 HLA-mismatched healthy volunteer pairs and 2 HLA-matched sibling donor/patient pairs.

Antibodies, Monoclonal↗
PubMed2001

Factors affecting thymic function after allogeneic hematopoietic stem cell transplantation.

Hematopoietic stem cell transplantation (HSCT) is followed by profound immunodeficiency. Thymic function is necessary for de novo generation of T cells after HSCT. Circulating CD45RA(+) naive T-cell levels are predictive of antigen-specific T-cell responses in the absence of graft-versus-host disease (GVHD). These T cells may not represent recent thymic emigrants, since naive T cells may maintain this phenotype if not antigen-activated. To accurately measure thymic output after HSCT and determine the factors that influence thymic function, T-cell receptor excision circles (TRECs) were examined in CD4(+) and CD8(+) cells from a cross-section of patients following HSCT. TREC levels rose weeks after HSCT and could be detected in patients 6 years after HSCT. TREC levels correlated with the frequency of phenotypically naive T cells, indicating that such cells were not expanded progeny of naive T cells present in the donor graft. Chronic GVHD was the most important factor that predicted low TREC levels even years after HSCT. Patients with a history of resolved GVHD had decreased numbers of TREC, compared with those with no GVHD. Because few adults had no history of GVHD, it was not possible to determine whether age alone inversely correlated with TREC levels. Recipients of cord blood grafts had no evidence of decreased TREC induced by immunosuppressive prophylaxis drugs. Compared with unrelated donor grafts, recipients of matched sibling grafts had higher TREC levels. Collectively, these data suggest that thymopoiesis is inhibited by GVHD. Larger studies will be needed to determine the independent contributions of age and preparative regimen to post-transplant thymopoietic capacity.

Adolescent↗
PubMed2001

Chronic graft-versus-host disease after hematopoietic cell transplantation presenting as an acute hepatitis.

A variety of illnesses involving the gut and liver follow hematopoietic cell transplantation (HCT). A 20 yr-old white male developed severe acute hepatitis 36 wk (day 252) after matched, unrelated, allogeneic HCT for chronic myelogenous leukemia (CML). Mild skin graft-versus-host disease (GVHD) had occurred at about 20 wk (day 140) after transplant. Liver biopsy showed bile duct injury and a diffuse lobular injury pattern most consistent with a GVHD variant and not reminiscent of drug-induced or viral hepatitis. No findings suggestive of herpesvirus, adenovirus, or varicella-zoster virus were found. High-dose steroids resulted in marked improvement of his liver enzyme levels. We report this patient as representing the acute hepatitic presentation of chronic GVHD of the liver.

Acute Disease↗
PubMed2000

In vitro selection of lentivirus vector-transduced human CD34+ cells.

Human CD34(+) cells with in vivo repopulating potential hold much promise as a target for corrective gene transfer for numerous hematopoietic disorders. However, the efficient introduction of exogenous genes into this small, quiescent population of cells continues to present a significant challenge. To circumvent the need for high initial transduction efficiency of human hematopoietic cells, we investigated a dominant selection strategy using a variant of the DHFR gene (DHFR(L22Y)). For this purpose, we constructed a lentivirus-based bicistronic vector expressing EGFP and DHFR(L22Y). Here we demonstrate efficient in vitro selection and enrichment of lentivirus vector-transduced human CD34(+) hematopoietic cells from fetal liver, umbilical cord blood, bone marrow, and peripheral blood after cytokine mobilization. Growth of transduced human CD34(+) cells in semisolid culture under selective pressure resulted in enrichment of transduced progenitor cells to 99.5% (n = 14). Selection for DHFR(L22Y)(+) cells after expansion of transduced progenitors in liquid culture resulted in a 7- to 13-fold increase in the percentage of marked cells. Thus we have shown that transduced human hematopoietic cells may be effectively enriched in vitro by dominant selection, suggesting that development of such strategies holds promise for future in vivo application.

Antigens, CD34↗
PubMed2000

Assessment of thymic output in adults after haematopoietic stem-cell transplantation and prediction of T-cell reconstitution.

BACKGROUND: The potential benefits of haematopoietic stem-cell transplantation are tempered by the depletion of T-cells accompanying this procedure. We used a new technique which quantifies the excisional DNA products of T-cell-receptor (TCR) gene rearrangement to measure thymic output directly in patients with multiple myeloma, and thus assessed the contribution of the thymus to immune recovery after transplantation. METHODS: We studied 40 patients, 34-66 years of age, who had been randomly assigned myeloablative chemotherapy and autologous peripheral-blood haematopoietic stem-cell transplantation with unmanipulated grafts or grafts enriched for CD34 stem cells. CD4 and CD8 T-cell counts were measured, thymic output was estimated serially until 2 years after transplantation, and percentages of naive T-cells were measured. FINDINGS: The production of substantial numbers of new naive T cells by the thymus could be detected by 100 days post-transplant; there was a significant inverse relation between age and recovery of new T cells. In the CD34-unselected group, numbers of TCR-rearrangement excision circles returned to baseline after 2 years, whereas in the CD34-selected group, numbers at 2 years were significantly higher than both baseline numbers (p=0.004), and 2-year numbers in the unselected group (p=0.046). Increased thymic output correlated with, and was predictive of, increased naive T-cell numbers and broader T-cell-receptor repertoires. INTERPRETATION: Our results provide evidence that the adult thymus contributes more substantially to immune reconstitution after haematopoietic stem-cell transplantation than was previously thought, and therefore could be a target for therapeutic intervention.

Adult↗
PubMed2000

Treatment of relapsed leukemia after unrelated donor marrow transplantation with unrelated donor leukocyte infusions.

The efficacy and toxicity of donor leukocyte infusions (DLI) after unrelated donor bone marrow transplantation (BMT) is largely unknown. We identified 58 recipients of unrelated DLI (UDLI) for the treatment of relapsed disease from the National Marrow Donor Program database. A retrospective analysis was performed to determine response, toxicity, and survival after UDLI and to identify factors associated with successful therapy. UDLI was administered for relapsed chronic myelogenous leukemia (CML) (n = 25), acute myelogenous leukemia (AML) (n = 23), acute lymphoblastic leukemia (ALL) (n = 7), and other diseases (n = 3). Eight patients were in complete remission (CR) before UDLI, and 50 were evaluable for response. Forty-two percent (95% confidence interval [CI], 28%-56%) achieved CR, including 11 of 24 (46%; 95% CI, 26%-66%) with CML, 8 of 19 (42%; 95% CI, 20%-64%) with AML, and 2 of 4 (50%; 95% CI, 1%-99%) with ALL. The estimated probability of disease-free survival (DFS) at 1 year after CR was 65% (95% CI, 50%-79%) for CML, 23% (95% CI, 9%-38%) for AML, and 30% (95% CI, 6%-54%) for ALL. Acute graft-versus-host disease (GVHD) complicated UDLI in 37% of patients (grade II-IV, 25%). A total of 13 of 32 evaluable patients (41%) developed chronic GVHD. There was no association between cell dose administered and either response or toxicity. In a multivariable analysis, only a longer interval from BMT to relapse and BMT to UDLI was associated with improved survival and DFS, respectively. UDLI is an acceptable alternative to other treatment options for relapse after unrelated donor BMT. (Blood. 2000;95:1214-1221)

Analysis of Variance↗
PubMed2000

Donor leukocyte infusions in acute lymphocytic leukemia.

Donor leukocyte infusion (DLI) has well-documented activity in CML but the role of DLI in other diseases is less well defined. To evaluate the strategy in acute lymphocytic leukemia (ALL) we evaluated 44 ALL patients from 27 centers who were treated with DLI. Patients with persistent or recurrent disease received DLI from the original marrow donor (30 matched related, four mismatched family, and 10 matched unrelated). Chemotherapy was given before DLI to 28 patients. Of 15 patients who received no pre-DLI chemotherapy, two achieved complete remissions, lasting 1112 and 764+ days. In four patients who received DLI as consolidation of remission induced by chemotherapy or immunosuppression-withdrawal, duration of remission post DLI was 65, 99, 195 and 672+ days. Of 25 patients who received DLI in the nadir after chemotherapy, 13 survived > or =30 days post DLI but did not achieve remission, seven died within less than 30 days post DLI, and five entered remissions that lasted 42, 68, 83, 90, 193 days. Seven patients who did not respond to the initial DLI received a second DLI; none of these patients attained durable remission. Eighteen of 37 evaluable patients developed acute GVHD and five of 20 evaluable patients developed chronic GVHD. Overall actuarial survival is 13% at 3 years. In conclusion, DLI has limited benefit in ALL. New approaches are needed in this group of patients.

Actuarial Analysis↗
PubMed2000

Donor leukocyte infusions for multiple myeloma.

Donor leukocyte infusion (DLI) has well-documented activity in CML, but the role of DLI in other diseases is less well defined. To evaluate the strategy in multiple myeloma (MM) we evaluated 25 MM patients from 15 centers who were treated with DLI. Patients with persistent or recurrent disease after allogeneic BMT received DLI from the original marrow donor (23 matched related, one mismatched family, and one matched unrelated). Chemotherapy was given before DLI in three patients. Two of 22 patients responded completely to DLI alone and three patients responded to the combination of DLI and chemotherapy. Nine patients who had not had sufficient disease control after DLI were given additional DLIs; five of these patients had either complete (two) or partial (three) responses. Thirteen of 25 evaluable patients developed acute GVHD and 11 of 21 evaluable patients developed chronic GVHD; all responders developed GVHD. No patients developed post-DLI pancytopenia. Four patients had responses which lasted >1 year after DLI, three patients had responses which lasted <1 year, and three patients had ongoing responses but with follow-up <1 year. In conclusion, DLI has anti-myeloma activity but the strategy is limited by no response or short duration of response in a significant percentage of patients and by significant GVHD in the majority of the responders.

Adult↗
PubMed1999

Long-term follow-up of patients who achieved complete remission after donor leukocyte infusions.

Donor leukocyte infusions (DLI) can induce a direct graft-vs-leukemia (GVL) reaction and restore complete remission for patients who relapse after allogeneic bone marrow transplantation (BMT). A critical and unanswered concern is the long-term safety and durability of DLI. To determine remission duration, long-term toxicity, and survival after DLI-induced remissions, we identified 73 patients who achieved complete remission after DLI. Follow-up information was obtained for 66 of the 73 patients, including 39 patients with chronic myelogenous leukemia (CML) and 27 patients with other diseases. Median follow-up for all patients was 32 months; the probability of survival at 1, 2, and 3 years was 83% (95% confidence interval [CI] 74-92), 71% (60-83), and 61% (49-74), respectively. For CML, survival probability at 1, 2, and 3 years was 87% (76-98), 76% (62-90), and 73% (58-88). For other diseases, survival probability at 1 and 2 years is 77% (61-93) and 65% (46-84). Five of 39 patients with CML relapsed, and 11 of 27 patients with other diseases relapsed. Treatment-related toxicity accounted for 10 deaths. Extended follow-up shows that DLI-induced remissions are durable, especially for patients with CML. Late relapses still occur, however, and toxicity remains significant. Continued follow-up will best define the long-term GVL effects of DLI, especially for diseases other than CML.

Adolescent↗
PubMed1999

Protracted results of dose-intensive therapy using cyclophosphamide, carmustine, and continuous infusion etoposide with autologous stem cell support in patients with relapse or refractory Hodgkin's disease: a phase II study from the North American Marrow Transplant Group.

To determine the long-term results of high-dose chemotherapy and stem cell support in relapsed or primary refractory Hodgkin disease patients. One hundred and thirty-one patients with relapsed or primary refractory Hodgkin's disease were treated with a dose-intensive therapy protocol consisting of etoposide (2400 mg/m2 continuous intravenous infusion) cyclophosphamide (7200 mg/m2 intravenously), and carmustine (300-600 mg/m2 intravenously) CBVi. All patients had previously failed conventional chemoradiotherapy. Severe toxicities were related to infectious, hepatic, and pulmonary complications. Fatal, regimen-related toxicity was 19%; liver and lung dysfunction, as well as infection, were the most frequent problems. Ninety-one (69%) of the patients achieved a complete response (CR) (95% CI = 59% to 75%) after CBVi and autologous stem cell infusion. With a median follow-up of 5.1 years (range 3.0 to 9.5 years), overall and event-free survival are 44% (95% CI = 33% to 47%) and 38% (95% CI = 28% to 46%) respectively. While univariate analysis did not reveal a statistically significant variable to predict a better response, responsiveness to therapy demonstrated a trend. We conclude that CBVi is an effective therapy for relapsed or refractory Hodgkin's disease, producing long-term, durable remissions.

Adolescent↗
PubMed1998

Treatment of T prolymphocytic leukemia with allogeneic bone marrow transplantation.

T prolymphocytic leukemia (T-PLL) is an unusual disease characterized by high white cell counts, older age at presentation, splenomegaly and a very aggressive clinical course. We describe a 47-year-old male with refractory T-PLL who was treated with high-dose chemoradiotherapy and allogeneic bone marrow transplantation (BMT) from an HLA-matched sibling. The transplant was complicated by both acute and chronic graft-versus-host disease (GVHD). The patient achieved complete remission and remains in remission 3 years after the transplant.

Bone Marrow Transplantation↗
PubMed1997

Donor leukocyte infusions in 140 patients with relapsed malignancy after allogeneic bone marrow transplantation.

PURPOSE: Recipients of allogeneic bone marrow transplants (BMTs) who have relapsed may attain complete remissions when treated with transfusions of leukocytes obtained from the original bone marrow donor. We performed a retrospective study to characterize better this new treatment modality. PATIENTS AND METHODS: We surveyed 25 North American BMT programs regarding their use of donor leukocyte infusions (DLI). Detailed forms were used to gather data regarding the original BMT, relapse, DLI, response to DLI, complications of DLI, and long-term follow-up evaluation. Reports of 140 patients were thus available for analysis. RESULTS: Complete responses were observed in 60% (95% confidence interval [CI], 51.9% to 68.1%) of chronic myelogenous leukemia (CML) patients who received DLI and did not receive pre-DLI chemotherapy; response rates were higher in patients with cytogenetic and chronic-phase relapse (75.7%; 95% CI, 68.2% to 83.2%) than in patients with accelerated-phase (33.3%; 95% CI, 19.7% to 46.9%) or blastic-phase (16.7%; 95% CI, 1.9% to 31.9%) relapse. The actuarial probability of remaining in complete remission at 2 years was 89.6%. Complete remission rates in acute myelogenous leukemia (AML) (n = 39) and acute lymphocytic leukemia (ALL) (n = 11) patients who had not received pre-DLI chemotherapy were 15.4% (95% CI, 9.6% to 21.2%) and 18.2% (95% CI, 6.6% to 29.8%), respectively. Complete remissions were also observed in two of four assessable myeloma patients and two of five assessable myelodysplasia patients. Complications of DLI included acute graft-versus-host disease (GVHD) (60%; 95% CI, 51.4% to 68.6%), chronic GVHD (60.7%; 95% CI, 50.3% to 71.1%), and pancytopenia (18.6%; 95% CI, 12.2% to 25.0%). Pre-DLI characteristics predictive of complete response in CML patients were post-BMT chronic GVHD, pre-DLI disease status of chronic phase, and time interval between BMT to DLI less than 2 years. Acute and chronic GVHD post-DLI were highly correlated with disease response (P < .00001). CONCLUSION: DLI results in complete remissions in a high percentage of patients with relapsed chronic-phase CML. Complete remissions are observed less frequently in patients with advanced CML and acute leukemia. GVHD and pancytopenia occur commonly; GVHD is highly correlated with response.

Actuarial Analysis↗
PubMed1997

Immune reconstitution with donor-derived memory/effector T cells after orthotopic liver transplantation.

Therapeutic hematopoietic stem cell transplantation has made great strides in recent years, providing curative therapy for many previously untreatable diseases. Nevertheless, the applicability and effectiveness of this procedure continues to be restricted by adverse immunoregulatory states, including graft rejection, graft vs. host disease (GvHD), and/or persistent immunodeficiency. Here, we provide evidence that long-term hematopoietic stem cell transplantation across major histocompatibility complex (MHC) barriers is possible in the human with limited adverse sequelae. We observed the rapid, complete, and stable replacement of recipient hematopoiesis and B lymphopoiesis with donor-derived cells approximately 6 weeks following orthotopic liver transplantation for hemochromatosis. Long-term T lineage reconstitution also occurred, but most intriguingly, derived almost exclusively from expansion of mature, memory/effector T cells from the transplanted liver. Although demonstrating both functional and molecular evidence of a simplified T cell receptor (TCR) repertoire and unable to become sensitized to "new" antigens (Ag), this patient demonstrated long-term clinical immunocompetence. Moreover, the transplanted T cells were effectively tolerant to host tissues as the patient did not manifest clinically significant GvHD off immunosuppressive therapy. These observations suggest that isolated memory/effector T cell populations have the potential of promoting stem cell engraftment in an allogeneic host without persistent GvHD, and to provide sufficient immune reconstitution to provide the recipient with long-term immune homeostasis.

ABO Blood-Group System↗
PubMed1996

A phase I study of bolus versus continuous infusion of the anti-CD19 immunotoxin, IgG-HD37-dgA, in patients with B-cell lymphoma.

IgG-HD37-SMPT-dgA is a deglycosylated ricin A chain (dgA)-containing immunotoxin (IT) prepared by conjugating the monoclonal murine (MoAb) anti-CD19 antibody, HD37, to dgA using the heterobifunctional hindered disulfide linker, N-succinimidyl-oxycarbonyl-alpha-methyl-alpha-(2-pyridyldithio) toluene (SMPT). In this report, we have used two regimens for the administration of IgG-HD37-SMPT-dgA to patients with non-Hodgkin's lymphoma (NHL) in two concomitant phase I trials. One trial examined four intermittent bolus infusions administered at 48-hour intervals. The other studied a continuous infusion (CI) administered over the same 8-day period. In the intermittent bolus regimen, the maximum tolerated dose (MTD) was 16 mg/m2/8 d and the dose-limiting toxicity (DLT) consisted of vascular leak syndrome (VLS), aphasia, and evidence of rhabdomyolysis encountered at 24 mg/m2/8 d. Using the CI regimen, the MTD was defined by VLS at 19.2 mg/m2/8 d. At the MTD of both regimens, a novel toxicity, consisting of acrocyanosis with reversible superficial distal digital skin necrosis in the absence of overt evidence of systemic vasculitis, occurred in 3 patients. Of 23 evaluable patients on the bolus schedule, there was 1 persisting complete response (CR; > 40 months) and 1 partial response (PR). Of 9 evaluable patients on the continuous infusion regimen, there was 1 PR. Pharmacokinetic parameters for the bolus regimen at the MTD showed a mean maximum serum concentration (Cmax) of 1,209 +/- 430 ng/mL, with a median T1/2 beta for all courses of 18.2 hours (range, 10.0 to 80.0 hours), a volume of distribution (Vd) of 10.9 L (range, 3.1 to 34.5 L), and a clearance (CL) of 0.45 L/h (range, 0.13 to 2.3 L/h). For the CI regimen at MTD, the mean Cmax was 963 +/- 473 ng/mL, with a median T1/2 beta for all courses of 22.8 hours (range, 24.1 to 30.6 hours), a Vd of 9.4 L (range, 4.4 to 19.5 L), and a CL of 0.32 L/h (range, 0.12 to 0.55 L/h). Twenty-five percent of the patients on the bolus infusion regimen and 30% on the CI regimen made antibody against mouse Ig (HAMA) and/or ricin A chain antibody (HARA). We conclude that this IT can be administered safely and that both regimens achieve comparable peak serum concentrations at the MTD; these concentrations are similar to those achieved previously using other regimens with IgG-dgA ITs at their respective MTDs. Thus, toxicity is related to the serum level of the IT and does not differ with different targeting MoAbs.

Adult↗
PubMed1996

FK506 (Tacrolimus) monotherapy for prevention of graft-versus-host disease after histocompatible sibling allogenic bone marrow transplantation.

FK506 (Tacrolimus) is an immunosuppressive drug that blocks the activation of antigen-specific T lymphocytes, a major component in the pathogenesis of graft-versus-host disease (GVHD). This study was designed to obtain first estimates of the safety and efficacy of FK506 monotherapy in the prevention of GVHD following HLA-identical sibling marrow transplantation. Additionally, a subset of patients was studied to define the pharmacokinetic profile of FK506. Twenty-seven adult patients with leukemia or myelodysplasia received FK506 starting the day before transplant at a dose of 0.04 mg/kg/d by continuous intravenous infusion. When clinically possible, FK506 was given orally in two divided doses starting at five times the daily intravenous dose. FK506 doses were adjusted to target a steady state or trough blood level between 10 to 30 ng/mL. These patients were followed for 6 months posttransplant. All patients had sustained marrow engraftment. Frequently noted adverse events included reversible renal dysfunction, diarrhea, fever, nausea, vomiting, and headache. Most patients required FK506 dose reductions associated with elevated serum creatinine. Two (7%) patients relapsed, one of whom died of the disease within the 6-month study period. A second patient died due to pulmonary mucor. Whole blood pharmacokinetic parameters indicated a half-life of 18.2 +/- 12.1 hours; volume of distribution of 1.67 +/- 1.02 L/kg; clearance of 71 +/- 34 mL/h/kg; and bioavailability of 32 +/- 24%. Eleven of 27 (41%) patients developed grade II to IV acute GVHD, including 10 grade II and one grade III. Six of 24 (25%) evaluable patients developed chronic GVHD. These data indicate that FK506 monotherapy has activity in preventing GVHD. Further studies of FK506 with lower doses to improve tolerability and in combination with other immunosuppressants to augment efficacy are warranted.

Adolescent↗