Peripheral blood marker of residual acute leukemia after hematopoietic cell transplantation using multi-plex digital droplet PCR

Background

Relapse remains the primary cause of death after hematopoietic cell transplantation (HCT) for acute leukemia. The ability to identify minimal/measurable residual disease (MRD) via the blood could identify patients earlier when immunologic interventions may be more successful. We evaluated a new test that could quantify blood tumor mRNA as leukemia MRD surveillance using droplet digital PCR (ddPCR).

Methods

The multiplex ddPCR assay was developed using tumor cell lines positive for the tumor associated antigens (TAA: WT1, PRAME, BIRC5), with homeostatic ABL1. On IRB-approved protocols, RNA was isolated from mononuclear cells from acute leukemia patients after HCT (n = 31 subjects; n = 91 specimens) and healthy donors (n = 20). ddPCR simultaneously quantitated mRNA expression of WT1, PRAME, BIRC5, and ABL1 and the TAA/ABL1 blood ratio was measured in patients with and without active leukemia after HCT.

Results

Tumor cell lines confirmed quantitation of TAAs. In patients with active acute leukemia after HCT (MRD+ or relapse; n=19), the blood levels of WT1/ABL1, PRAME/ABL1, and BIRC5/ABL1 exceeded healthy donors (p<0.0001, p=0.0286, and p=0.0064 respectively). Active disease status was associated with TAA positivity (1+ TAA vs 0 TAA) with an odds ratio=10.67, (p=0.0070, 95% confidence interval 1.91 - 59.62). The area under the curve is 0.7544. Changes in ddPCR correlated with disease response captured on standard of care tests, accurately denoting positive or negative disease burden in 15/16 (95%). Of patients with MRD+ or relapsed leukemia after HCT, 84% were positive for at least one TAA/ABL1 in the peripheral blood. In summary, we have developed a new method for blood MRD monitoring of leukemia after HCT and present preliminary data that the TAA/ABL1 ratio may may serve as a novel surrogate biomarker for relapse of acute leukemia after HCT.

Oral disease profiles in chronic graft versus host disease

At least half of patients with chronic graft-versus-host-disease (cGVHD), the leading cause of morbidity and non-relapse mortality after allogeneic stem cell transplantation, have oral manifestations: mucosal lesions, salivary dysfunction, and limited mouth-opening. cGVHD may manifest in a single organ or affect multiple organ systems, including the mouth, eyes, and the skin. The interrelationship of the 3 oral manifestations of cGVHD with each other and with the specific manifestations of extraoral cGVHD has not been studied. In this analysis, we explored, in a large group of patients with cGVHD, the potential associations between: (1) oral mucosal disease and erythematous skin disease, (2) salivary gland dysfunction and lacrimal gland dysfunction, and (3) limited mouth-opening and sclerotic skin cGVHD. Study participants, enrolled in a cGVHD Natural History Protocol (NCT00331968, n = 212), underwent an oral examination evaluating: (1) mucosal cGVHD [NIH Oral Mucosal Score (OMS)], (2) salivary dysfunction (saliva flow and xerostomia), and (3) maximum mouth-opening measurement. Parameters for dysfunction (OMS > 2, saliva flow ≤ 1 mL/5 min, mouth-opening ≤ 35 mm) were analyzed for association with skin cGVHD involvement (erythema and sclerosis, skin symptoms), lacrimal dysfunction (Schirmer's tear test, xerophthalmia), Lee cGVHD Symptom Scores, and NIH organ scores. Oral mucosal disease (31% prevalence) was associated with skin erythema (P < 0.001); salivary dysfunction (11% prevalence) was associated with lacrimal dysfunction (P = 0.010) and xerostomia with xerophthalmia (r = 0.32, P = 0.001); and limited mouth-opening (17% prevalence) was associated with skin sclerosis (P = 0.008) and skin symptoms (P = 0.001). There was no association found among these 3 oral cGVHD manifestations. This analysis supports the understanding of oral cGVHD as 3 distinct diseases: mucosal lesions, salivary gland dysfunction, and mouth sclerosis. Clear classification of oral cGVHD as 3 separate manifestations will improve clinical diagnosis, observational research data collection, and the definitions of outcome measures in clinical trials.

NIH response criteria measures are associated with important parameters of disease severity in patients with chronic GVHD

Lack of standardized criteria measuring therapeutic response remains an obstacle to the development of better treatments for chronic GVHD (cGVHD). This cross-sectional prospective study examined the concurrent and predictive validity of 18 clinician-reported ('Form A') and 8 patient-reported ('Form B') response measures proposed by NIH criteria. Concurrent parameters of interest were NIH global score, cGVHD activity, Lee symptom score and SF36 PCS. Patient cohort included 193 adults with moderate-to-severe cGVHD. Measures associated with the highest number of outcomes were lung function score (LFS), 2-min walk, grip strength, 4-point health-care provider (HCP) and patient global scores, 11-point clinician- and patient-reported global symptom severity scores, and Karnofsky performance score (KPS). Measures associated with survival in univariate analyses led to a Cox model containing skin erythema, LFS, KPS, eosinophil count and interval from cGVHD diagnosis to enrollment as jointly associated with survival. In conclusion, 4-point HCP and patient global scores and 11-point clinician- and patient-reported global symptom severity scores are associated with the majority of concurrent outcomes. Skin erythema is a potentially reversible sign of cGVHD that is associated with survival. These results define a subset of measures that should be prioritized for evaluation in future studies.

Comparative analysis of FoxP3(+) regulatory T cells in the target tissues and blood in chronic graft versus host disease

Activation and migration of regulatory T cells (Treg) into tissue is critical in control of inflammation, but has not been examined extensively in chronic graft versus host disease (cGVHD). In parallel studies of tissues and blood, we determined that FoxP3(+) T cells increased in proportion to T effectors (Teff) in tissue infiltrates in oral and cutaneous lichenoid cGVHD. These FoxP3(+) cells expressed distinguishing phenotypic and functional markers of Treg (CD3(+), CD4(+), CD27(+), ICOS(+) and CD39(+)), not found on FoxP3(-) Teff. Both Teff and FoxP3(+) Treg expressed T-bet and the chemokine receptor CXCR3, however, consistent with a common mechanism of chemokine-mediated migration into tissue. Furthermore, functional markers (ICOS and CD39) and chemokine receptors (CXCR3) were both present in a higher proportion of FoxP3(+) cells in tissues than in peripheral blood, consistent with recruitment and activation of Treg in cGVHD target tissues. Finally, the 'activated' CD45RA(-)FoxP3(hi) subset of Treg cells, which highly express functional markers, were found in comparable frequencies in cGVHD patients and normal controls, despite a significant deficit in naive 'resting' Treg. These findings are consistent with Treg capacity to upregulate functional markers and traffick into tissue in cGVHD.

Oral chronic graft-vs.-host disease characterization using the NIH scale

Chronic graft-vs.-host disease (cGVHD) is a complication of allogeneic hematopoietic stem cell transplantation (alloHSCT). Oral cGVHD is manifested by mucosal, salivary, and/or sclerotic changes that have been linked to pain and poor quality of life. Our aim was to describe the demographic, clinical, and laboratory markers of oral cGVHD in alloHSCT patients (N = 187) enrolled in a cGVHD cross-sectional study at the NIH (#NCT00331968). We propose a meaningful and reproducible measure of disease defined by a cut-off point reflecting clinical minimally detectable change (0-2 = no oral cGVHD, 3-15 = oral cGVHD) on the 15-point NIH cGVHD clinician assessment scale. Forty-four patients had oral cGVHD. Oral cGVHD was associated with a quiescent or de novo type of cGVHD onset (p = 0.05), higher cGVHD severity (p = 0.033), lower albumin (p = 0.0008), higher total complement (p = 0.012), greater bother from foods or oral ulcers and greater mouth pain, and sensitivity (p < 0.0001). Multivariable logistic regression modeling with albumin, mouth pain, and total complement was 74.3% predictive of oral cGVHD and 80.2% predictive of non-oral cGVHD. We propose the use of >2 points on the NIH scale as a reproducible definition of clinically significant oral cGVHD, which may be useful in clinical settings or as eligibility criterion or as an endpoint in clinical trials.

No increased mortality from donor or recipient hepatitis B- and/or hepatitis C-positive serostatus after related-donor allogeneic hematopoietic cell transplantation

Limited data exist on allogeneic transplant outcomes in recipients receiving hematopoietic cells from donors with prior or current hepatitis B (HBV) or C virus (HCV) infection (seropositive donors), or for recipients with prior or current HBV or HCV infection (seropositive recipients). Transplant outcomes are reported for 416 recipients from 121 centers, who received a human leukocyte antigen-identical related-donor allogeneic transplant for hematologic malignancies between 1995 and 2003. Of these, 33 seronegative recipients received grafts from seropositive donors and 128 recipients were seropositive. The remaining 256 patients served as controls. With comparable median follow-up (cases, 5.9 years; controls, 6.7 years), the incidence of treatment-related mortality, survival, graft-versus-host disease, and hepatic toxicity, appears similar in all cohorts. The frequencies of hepatic toxicities as well as causes of death between cases and controls were similar. Prior exposure to HBV or HCV in either the donor or the recipient should not be considered an absolute contraindication to transplant.

Clinical laboratory markers of inflammation as determinants of chronic graft-versus-host disease activity and NIH global severity

Chronic graft versus host disease (cGVHD) remains a major cause of non-relapse morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Currently there are no accepted measures of cGVHD activity to aid in clinical management and disease staging. We analyzed clinical markers of inflammation in the sera of patients with established cGVHD and correlated those with definitions of disease activity. 189 adults with cGVHD (33% moderate and 66% severe according to NIH global scoring) were consecutively enrolled onto a cross-sectional prospective cGVHD natural history study. At the time of evaluation, 80% were receiving systemic immunosuppression and failed a median of 4 prior systemic therapies (PST) for their cGVHD. Lower albumin (p<0.0001), higher CRP (C-reactive protein; p=0.043), higher platelets (p=0.030) and higher number of PST (p<0.0001) were associated with active disease defined as clinician's intention to intensify or alter systemic therapy due to the lack of response. Higher platelet count (p=0.021) and higher number of PST (p<0.0001) were associated with more severe diseased defined by NIH global score. This study identified common laboratory indicators of inflammation that can serve as markers of cGVHD activity and severity.

EPOCH-F: A salvage regimen for multiple myeloma prior to reduced intensity allogenic hematopoietic stem cell transplantation

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Background: Variation in baseline host immune status contributes to inconsistent donor engraftment and may impede maximal graft-versus-myeloma effects after reduced intensity allogenic hematopoietic stem cell transplantation (RIHSCT) for advanced multiple myeloma (MM). As no specific salvage regimen has been designed for MM patients being considered for RIHSCT, we evaluated EPOCH-F a novel salvage regimen designed to provide disease control and immune depletion. Methods: EPOCH-F is an infusional chemotherapeutic regimen consisting of etoposide, vincristine and adriamycin, with prednisone, cyclophosphamide and fludarabine given in 21 day cycles prior to RIHSCT. Targeting a CD4+ T cell count, 22 pts were treated <5 cycles of EPOCH-F. Pts proceeded to RIHSCT after adequate lymphodepletion or if there was disease progression during EPOCH-F, regardless of CD4 count. Results: Median age was 53 years (range 36–65); median time from initial therapy to transplant was 12 months (range 2–168). Median number of prior therapies was 2 (range 1–8), 63% had chemotherapy sensitive disease and 68% had received a novel agent. Pts received a median of 3 cycles (range 1–5), with manageable toxicities, mostly hematologic. Grade IV Neutropenia was seen in 77% of the administered cycles with only 6 episodes of neutropenic fever. Median lymphocyte count decreased from 1423/μL (range 335–2788) to 519/μL (range 102–1420); CD4 count decreased from 320/μL (range 130–1366) to 115/μL (30–309). In 21 evaluable pts, the ≥PR rate to EPOCH-F was 22% with 13% CR/nCR. 68% had SD and only 1 pt progressed. 20 pts underwent RIHSCT from HLA matched sibling. Median Day 100 chimerism was 100% (range 60–100, mean 95). 70% of patients achieved ≥VGPR and CR/nCR was seen in 40%. Acute GVHD (grade II-IV) was seen in 47% and chronic GVHD (grade III-IV) was seen in 52% of the pts. TRM at 100 days was 5% and 30% at 60 months. Median overall survival of patients after RIHSCT was 46.1 months. Conclusions: EPOCH-F is an active regimen which provides pre-transplantation lympho-depletion, disease control and allows consistent engraftment in multiple myeloma patients undergoing RIHSCT.

No significant financial relationships to disclose.

Clinical evidence of a graft-versus-lymphoma effect against relapsed diffuse large B-cell lymphoma after allogeneic hematopoietic stem-cell transplantation

BACKGROUND

A graft-versus-lymphoma effect against diffuse large B-cell lymphoma (DLBCL) is inferred by sustained relapse-free survival after allogeneic stem-cell transplantation; however, there are limited data on a direct graft-versus-lymphoma effect against DLBCL following immunotherapeutic intervention by either withdrawal of immunosuppression or donor lymphocyte infusion (DLI).

MATERIALS AND METHODS

An analysis was carried out to determine whether a direct graft-versus-lymphoma effect exists against DLBCL. The analysis was restricted to patients with DLBCL, who were either not in complete remission at day +100 after allogeneic stem-cell transplantation or subsequently relapsed beyond this time point.

RESULTS

Fifteen patients were identified as either not in complete remission (n = 13) at their day +100 evaluation or subsequently relapsed (n = 2) and were assessed for subsequent responses after withdrawal of immunosuppression or DLI. Eleven patients were treated with either withdrawal of immunosuppression (n = 10) or a DLI (n = 1) alone; four patients received chemotherapy with DLI to reduce tumor bulk. Nine (60%) patients subsequently responded (complete = 8, partial = 1). Six responses occurred after withdrawal of immunosuppression alone. Six patients are alive (range 42-83+ months) in complete remission without further treatment.

CONCLUSION

The demonstration of sustained complete remission following immunotherapeutic intervention provides direct evidence of a graft-versus-lymphoma effect against DLBCL.

Animal models of acute and chronic graft-versus-host disease

Graft-versus-host disease (GVHD) represents a special situation in transplantation immunology in which immunocompetent donor cells are engrafted into recipients that are incapable of rejecting them due to tolerance, immaturity, or radiation- or chemotherapy-induced immune deficiency. Donor T cells encountering allogeneic stimulators become activated, secrete cytokines, proliferate, and differentiate into effectors; this in vivo immune response is known as the graft-versus-host reaction (GVHR). The systemic effects of this initial donor anti-host reaction comprise a multiorgan syndrome, graft-versus-host disease (GVHD). Murine GVHD experiments have been utilized to model the clinical disorders of acute and chronic GVHD (AGVHD and CGVHD) that occur after allogeneic bone marrow transplantation, and also to study T cell regulation, induction of tolerance, and autoimmune diseases. Presented in this unit are methods for generating and assessing both AGVHD and CGVHD in mice. While the two syndromes differ markedly in immunopathogenesis, both can be induced by the two main methods presented: transfer of allogenic donor lymphocytes and stem cells into irradiated hosts, and transfer of parental strain lymphocytes and stem cells into unirradiated, immune-competent F1 strain hosts. Several endpoints of AGVHD and CGVHD should be evaluated in experimental mice, with comparisons made to the syngeneic transplant control or the T cell-depleted allogeneic control. To this end, protocols are provided for the assessment of survival rates, weight loss, chimerism, donor-host cytotoxicity, and cytokine and proliferative responses to mitogenic or allogeneic stimuli. Histopathology and assays of B cell immune function are also described for evaluation of the pathogenesis of GVHD.

A comparison and critical analysis of preclinical anticancer vaccination strategies

Anticancer vaccines have been extensively studied in animal models and in clinical trials. While vaccination can lead to tumor protection in numerous murine models, objective tumor regressions after anticancer vaccination in clinical trials have been rare. B16 is a poorly immunogenic murine melanoma that has been extensively used in anticancer vaccination experiments. Because B16 has been widely used, different vaccination strategies can be compared. We reviewed the results obtained when B16 was treated with five common vaccine types: recombinant viral vaccines, DNA vaccines, dendritic cell vaccines, whole-tumor vaccines, and peptide vaccines. We also reviewed the results obtained when B16 was treated with vaccines combined with adoptive transfer of tumor antigen-specific T cells. We found several characteristics of vaccination regimens that were associated with antitumor efficacy. Many vaccines that incorporated xenogeneic antigens exhibited more potent anticancer activity than vaccines that were identical except that they incorporated the syngeneic version of the same antigen. Interleukin-2 enhanced the antitumor efficacy of several vaccines. Finally, several effective regimens generated large numbers of tumor antigen-specific CD8(+) T cells. Identification of vaccine characteristics that are associated with antitumor efficacy may aid in the development of more effective anticancer vaccination strategies.

Immunosenescence: deficits in adaptive immunity in the elderly

Aging is associated clinically with increases in the frequency and severity of infectious diseases and an increased incidence of cancer, chronic inflammatory disorders and autoimmunity. These age-associated immune dysfunctions are the consequence of declines in both the generation of new naïve T and B lymphocytes and the functional competence of memory populations. These alterations collectively are termed immunosenescence.

Propagation of mouse and human T cells with defined antigen specificity and function

Difficulties maintaining fully functional CD4+ T cells in culture have historically limited the study of their role in tumour rejection as well as other clinical applications. As the therapeutic value of current antitumour CD8+ T cell adoptive therapy becomes better defined, a strong impetus exists to determine optimal conditions for culturing antitumour CD4+ T cells. Our goal is to promote broadly polyclonal, antigen-specific CD4+ T cell responses of either Th1 or Th2 character for use in antitumour therapy or allograft facilitation, respectively. Similar obstacles exist in murine and human cultures: (1) during even brief periods of culture CD4+ T cells develop high 'background' reactivity to class II-positive antigen-presenting cells; (2) maintenance of antigen specificity as evidenced by cytokine secretion and short-term proliferation assays is insufficient to ensure bulk numerical expansion; (3) Th1-type CD4+ T cells often lose their potential for antigen-specific secretion of interleukin 2 on re-stimulation (though remain inducible by 12-O-tetradecanoylphorbol 13-acetate/ionomycin); (4) during prolonged culture selection pressure favours CD4+ subpopulations that recognize artifactual antigens such as culture medium proteins; (5) even with optimal culture conditions, cultured CD4+ T cells may function differently in vivo to uncultured CD4+ T cells. We have devised various strategies to surmount these obstacles by use of selected cytokines, antigen-presenting cells and timely culture manoeuvres.

The relationship between body mass index and per cent body fat in the severely obese

BACKGROUND

International standards define clinical obesity according to body mass index (BMI) without reference to age and gender. Recent studies among adults in the normal to mildly obese BMI ranges have shown that the relationship between BMI and per cent body fat (% fat) differs by age and gender. The extent to which age and gender affect the relationship between BMI and % fat among more severely obese individuals is less known.

AIM

The aim was to examine the age-gender association between measured BMI and % fat from a large cohort of adults, including a large number of severely obese subjects (1862 with a BMI > or = 35 kg/m(2)).

METHODS

BMI was computed from measured height and weight, and % fat was estimated from bioelectrical impedance in 3068 adults. Two impedance equations, the Sun equation and the Heath equation (specific to severe obesity), were used to calculate % fat.

RESULTS

Average age for 991 men and 2077 women was 46 +/- 15 vs. 44 +/- 14 years respectively (p = 0.0003). The average BMI was 36 +/- 9 kg/m(2) for men and 39 +/- 10 kg/m(2) for women (p < 0.0001), with a combined gender BMI range of 19-74 kg/m(2). Using the Sun equation, average % fat was 31 +/- 8 vs. 46 +/- 8% (p < 0.0001) for all men and women respectively. With the Sun equation, age-adjusted Spearman correlations between all BMI and % fat values were r = 0.80 and r = 0.83 for men and women, respectively, but only 0.60 (n = 479) and 0.61 (n = 1383) in severely obese participants (BMI > or = 35 kg/m(2)). Using the Heath equation, only for participants with BMI > or = 35 kg/m(2), the age-adjusted Spearman correlations improved to r = 0.82 (n = 479) and r = 0.70 (n = 1383) for men and women respectively. Finally, by combining the Sun equation for subjects with BMI < 35 kg/m(2) and the Heath equation for those with BMI > or = 35 kg/m(2), correlations improved to 0.89 for men and 0.87 for women. Using these combined equations, the relationship between BMI and % fat was best fit as a linear function for men and curvilinear function (both p < 0.001) for women across the range of BMI. The % fat was approximately 10% higher for any BMI value among women vs. men even among the severely obese (p < 0.0001).

CONCLUSIONS

These data that include a large cohort of severely obese individuals demonstrated a linear association between BMI and % fat for men and a curvilinear association between BMI and % fat for women when Sun and Heath equations were combined. Assuming disease risk is driven by adiposity, this study suggests a need to further explore the appropriateness of gender-specific BMI cutpoints for clinical risk assessment due to the marked difference in the BMI-per cent fat relation observed in men and women across the entire range of BMI.

Association of serum interleukin-7 and interleukin-15 levels with immune reconstitution (IR), graft-versus-host disease (GVHD), and survival after reduced-intensity allogeneic stem cell transplantation (RIST)

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Background: In laboratory models, interleukin-7 (IL-7) and IL-15 significantly influence IR after allogeneic stem cell transplantation (SCT), thereby affecting immunity, graft-versus-malignancy (GVM) effects, and GVHD. Interleukin-7 (IL-7) is the main homeostatic regulator of naïve CD4+ and CD8+ T cells, and IL-15 is homeostatic for CD8+ memory and effector T cells and NK cells. The contributions of these cytokines to IR after allogeneic SCT are not well characterized in a clinical setting. Methods: We studied serum IL-7 and IL-15 levels in 31 pts with hematologic malignancies undergoing RIST from HLA-matched siblings in a prospective trial. Pts received identical transplant conditioning (fludarabine/cyclophosphamide) and GVHD prophylaxis (CSA/MTX). IL-7 and IL-15 levels and peripheral blood lymphocyte subpopulations (ALC, CD3, CD4, CD8, B, NK, and NKT) were measured before RIST, and post RIST at 1 and 2 weeks; 1, 2, 3, 6, 9, and 12 months. Results: Consistent with their homeostatic effects, IL-7 and IL-15 levels rose from baseline as transplant conditioning induced lymphopenia, and then decreased with lymphocyte recovery. These inverse correlations were strongest within 1 month post RIST. In an exploratory analysis, IL-15 levels at day 0 were correlated with baseline age (r=0.49; p=0.0058) and were higher among patients with CMV reactivation after RIST (p=0.048). At 2 weeks post RIST, higher IL-7 levels were strongly associated with subsequent acute GVHD (p=0.000033), and higher IL-15 levels were associated with inferior survival (p=0.007), mainly from relapse. At 3 months post RIST, superior survival was associated with higher NK cell counts (p=0.0008), and to a lesser extent with higher CD4 counts (p=0.036). Conclusions: These data support preclinical observations that IL-7 promotes GVHD after allogeneic SCT. The association of higher post-RIST IL-15 levels with death from relapse may identify pts with impaired IR leading to inadequate GVM effects. This hypothesis is consistent with the finding that higher NK cell counts after RIST were associated with better survival. Further studies must confirm the hypotheses generated in this setting.

No significant financial relationships to disclose.

Targeted immune depletion prior to reduced-intensity allogeneic stem cell transplantation results in rapid and complete donor chimerism with low treatment-related mortality

6540

Background: Significant variation in host immune status may influence outcomes after reduced-intensity (RI) allogeneic stem cell transplantation (alloSCT). We have investigated a strategy of targeted immune depletion (TID) with conventional chemotherapy to deplete host T cells and achieve a minimal disease state prior to RI alloSCT. The aim of TID is to rapidly establish complete donor chimerism after RI alloSCT in order to potentiate a graft-versus-tumor (GVT) effect. In a prospective phase II trial (NIH 03-C-0077), we evaluated the effect of TID on donor chimerism, acute graft-versus-host disease (GVHD), and clinical outcome. Methods: Thirty-one patients (pts) with relapsed and refractory hematologic malignancies (NHL = 16; HL = 4; CLL/PLL = 4; MDS/AML = 3; other = 4) were enrolled. Median age was 57 years (range: 31–71). All pts received EPOCH-F (etoposide, prednisone, vincristine, cyclophosphamide, adriamycin, fludarabine) ± rituximab (R) as TID to deplete host CD4+ cells <100/μL. All pts then received a RI conditioning regimen consisting of fludarabine and cyclophosphamide followed by a T-cell replete allograft from HLA-matched siblings. GVHD prophylaxis consisted of cyclosporine plus short-course mini-methotrexate. Results: EPOCH-F(R) achieved the target host T-cell level in 74% of pts. All 31 pts engrafted after RI alloSCT. Complete donor chimerism (> 95%) was observed in 74% and 81% of pts at day +14 and +28 post-transplant, respectively. The incidence of grade II-III acute GVHD was 42% with no cases of grade IV acute GVHD. The median potential follow-up from transplant is 25 months. Actuarial treatment-related mortality at 1 and 2 years was 3% and 8%, respectively. Event-free survival probabilities at 1 and 2 years post-transplant are 65% and 49%, respectively. Ten pts are alive and event-free >24 months post-transplant. The overall survival probabilities at 1 and 2 years are 84% and 64%, respectively. Conclusions: TID prior to RI alloSCT results in rapid, complete donor engraftment and may potentiate GVT effects. This treatment strategy was associated with very low TRM and favorable outcomes in an older patient population with advanced hematologic malignancies.

No significant financial relationships to disclose.

Perspectives in post-transplantation immunotherapy in breast cancer

High risk and metastatic breast cancer remain a major therapeutic challenge. Although the role of high dose chemotherapy followed by stem cell transplantation (SCT) in the overall treatment strategy is not yet well defined, it is clear that new forms of therapy such as immunotherapy will be needed to cure the majority of patients with advanced disease. We review important considerations for immunotherapy in the post-transplantation period. Experimental and clinical data suggest that immunotherapy may be most effective in a state of minimal residual disease such as that achieved following SCT. However, high dose therapy and autologous SCT result in an iatrogenic immune deficiency, which compounds the suppression of the immune system associated with tumor itself. Understanding reconstitution of a functional immune system post transplantation is critical in devising clinically effective immune interventions. A review of the clinical studies of post transplant immunotherapy for breast cancer is presented including autologous and allogeneic strategies, as well as perspectives for future development.

Thromboembolism following removal of femoral venous apheresis catheters in patients with breast cancer

BACKGROUND

Apheresis catheters have simplified collection of peripheral blood stem cells (PBSC), but may be associated with thrombosis of the instrumented vessels. We performed a retrospective analysis to study the prevalence of thromboembolism associated with the use of femoral apheresis catheters in patients with breast cancer.

PATIENTS AND METHODS

Patients were participants in clinical trials of high-dose chemotherapy with autologous PBSC rescue. They underwent mobilization with either high-dose cyclophosphamide (n = 21) or cyclophosphamide/paclitaxel (n = 64), followed by filgrastim. Double lumen catheters (12 or 13 Fr) were placed in the femoral vein and removed within 12 h of the last apheresis procedure. Apheresis was performed using a continuous flow cell separator and ACD-A anticoagulant. Thromboembolism was diagnosed by either venous ultrasonography or ventilation-perfusion scan.

RESULTS

Nine of 85 patients (10.6%) undergoing large volume apheresis with use of a femoral catheter developed thromboembolic complications. Pulmonary embolus (PE) was diagnosed in five and femoral vein thrombosis in four patients. Four of the five patients who developed PE were symptomatic; one asymptomatic patient had a pleural-based, wedge-shaped lesion detected on a staging computed tomography scan. The mean number of apheresis procedures was 2.4 (range one to four) and the mean interval between removal of the apheresis catheter and diagnosis of thrombosis was 17.6 days. In contrast, none of 18 patients undergoing apheresis using jugular venous access and none of 54 healthy allogeneic donors undergoing concurrent filgrastim-mobilized PBSC donation (mean 1.7 procedures/donor) using femoral access experienced thromboembolic complications.

CONCLUSIONS

Thromboembolism following femoral venous catheter placement for PBSC collection in patients with breast cancer may be more common than previously recognized. Healthy PBSC donors are not at the same risk. Onset of symptoms related to thrombosis tended to occur several weeks after catheter removal. This suggests that the physicians not only need to be vigilant during the period of apheresis, but also need to observe patients for thromboembolic complications after the catheter is removed. The long interval between the removal of apheresis catheter and the development of thromboembolism may have a potential impact on prophylactic strategies developed in future, such as the duration of prophylactic anticoagulation. Avoidance of the femoral site in breast cancer patients, and close prospective monitoring after catheter removal, are indicated.

Selection and expansion of T cell from untreated patients with CLL: source of cells for immune reconstitution?

BACKGROUND

Lymphocyte-derived malignancies can be treated with combinations of drugs that efficiently eradicate normal and malignant lymphocytes. Lack of T lymphocytes after treatment of B lymphocyte CLL (B-CLL) makes the patients susceptible to serious infections and may limit the benefit of the therapy. The aim of the study was to purify and culture-expand normal T lymphocytes from B-CLL patients prior to therapy. These cells could be frozen and given to the patients in the lymphopenic period post-chemotherapy.

METHODS

T lymphocytes were isolated from the mononuclear cell apheresis products from five patients with previously untreated B-CLL. The apheresis products were red-cell depleted by density gradient centrifugation. B-lymphocyte purging was performed by incubating with MAbs to four different B-cell epitopes, followed by magnetic-bead depletion. One round of negative selection removed >90% of the B lymphocytes. The T-lymphocyte enriched cell suspension was cultured for 10/11 days in the presence of IL-2 and the anti-T cell receptor Ab OKT3. In addition, in some cultures anti-CD22 ricin immunotoxin was added.

RESULTS

T cells from CLL patients expanded 4.7-21-fold over a 10/11 days culture interval. After culture, CLL cells could no longer be identified by flow cytometric evaluation. The cultured T lymphocytes were predominantly CD8(+), and were capable of lysing autologous CLL cells through a fas-dependent mechanism.

DISCUSSION

Selection and expansion of T lymphocytes by this method may represent a strategy for enhancing immunity in the lymphopenic period following CLL treatment.

Suppression of T-cell responsiveness by inducible cAMP early repressor (ICER)

Depending on the nature of the costimulation of T lymphocytes, expression of regulatory cytokines and chemokines is either susceptible or resistant to cyclic AMP (cAMP)-mediated inhibition. Our data show that cAMP-mediated inhibition of endogenously expressed cytokines, which is characteristic for T helper (Th) 1- and Th 2-like phenotypes, correlates with the induction of a potent transcriptional repressor, inducible cAMP early repressor (ICER), in both subsets of T cells activated under conditions of suboptimal interleukin-2 (IL-2) expression. Importantly, Th-specific expression of certain chemokines is also susceptible to cAMP-mediated transcriptional attenuation. To determine whether ICER per se, rather than forskolin-mediated elevation of intracellular cAMP, is responsible for the observed inhibitory effect, we generated transgenic mice expressing ICER under the control of a lymphocyte-specific lck promoter. On stimulation, transgenic thymocytes overexpressing ICER exhibited reduced levels of IL-2 and interferon (IFN)-gamma and failed to express the macrophage inflammatory protein (MIP)-1alpha and MIP-1beta genes. Splenic T cells from ICER-transgenic mice showed a defect in proliferation and lacked a mixed lymphocyte reaction response, implying that ICER-mediated inhibition of cytokine and chemokine expression might play an important role in T-cell inactivation.

Modulation of graft-versus-tumor effects in a murine allogeneic bone marrow transplantation model by tumor-derived transforming growth factor-betaI

Although graft-versus-leukemia effects in allogeneic bone marrow transplantation (alloBMT) are well documented, graft-versus-tumor (GVT) effects are poorly defined. To investigate the latter, we established a murine model of breast cancer using TS/A, a transforming growth factor (TGF)-beta1-secreting breast cancer cell line of BALB/c origin. In the setting of disparate (parent into F1) alloBMT, no appreciable GVT was identified. To assess whether TGF-beta1 secreted by the tumor might inhibit the antitumor response, TGF-beta1 antisense vector was transfected into the TS/A breast cancer cell line. Mice were inoculated with either TGF-beta1 antisense transfected or the mock transfected cell line and underwent syngeneic or alloBMT. No evidence of GVT was appreciated for the mock-transfected breast cancer cell line as assessed by an absence of a statistically significant difference in survival between syngeneic and alloBMT groups. However, there was a highly statistically significant survival difference between allogeneic versus syngeneic bone marrow transplantation groups inoculated with the TGF-beta1 antisense-transfected cell line (P = .00001) as well as when comparing the survival of mice that received alloBMT for TGF-beta1 antisense-transfected tumor versus mock-transfected tumor (P = .0008). These data suggest that (1) GVT exists against the antisense-transfected breast cancer cells in this experimental model and (2) TGF-beta1 may be involved in suppressing antitumor responses in the setting of alloBMT for breast cancer.

Interleukin-7 restores immunity in athymic T-cell-depleted hosts

Thymic-deficient hosts rely primarily on antigen-driven expansion to restore the peripheral T-cell compartment following T-cell depletion (TCD). The degree to which this thymic-independent pathway can restore immune competence remains poorly understood but has important implications for a number of clinical conditions including stem cell transplantation and human immunodeficiency virus (HIV) infection. A model of HY-mediated skin graft rejection by athymic, TCD mice was used to show that restoration of naive and recall responses via peripheral expansion requires transfer of only 25 x 10(6) lymph node (LN) cells representing approximately 10% of the T-cell repertoire. Constitutive expression of bcl-2 in the expanding inocula restored recall responses to HY at a substantially lower LN cell dose (1 x 10(6)), which is normally insufficient to induce HY-mediated graft rejection in athymic hosts. Interestingly, bcl-2 had no effect on primary responses. Interleukin-7 (IL-7) potently enhanced thymic-independent peripheral expansion and led to HY graft rejection using an LN cell dose of 1 x 10(6) in both primary and recall models. The restoration of immune competence by IL-7 appeared to be mediated through a combination of programmed cell death inhibition, improved costimulation, and modulation of antigen-presenting cell (APC) function. These results show that immune competence for even stringent antigens such as HY can be restored in the absence of thymic function and identify IL-7 as a potent modulator of thymic-independent T-cell regeneration.

Veto activity of activated bone marrow does not require perforin and Fas ligand

Veto cells suppress generation of CD8(+) T cell immune responses in an antigen-specific manner, with specificity dictated by antigens on the veto cell surface. Activated bone marrow (ABM) veto cells belong to the NK cell type lineage and veto by clonally deleting antigen-specific precursor cytotoxic T cell lymphocyte (CTL). In vitro cytotoxicity of ABM depends largely on the perforin/granzyme and Fas/Fas ligand pathways. Utilizing perforin-deficient and functional Fas ligand-deficient gld mice as a source of ABM and functional Fas-deficient lpr mice as a source of precursor CTL, we demonstrate in this study that ABM cells utilize a perforin- and Fas-independent pathway to veto allogeneic cell-mediated cytotoxic responses. We also show that ABM cells mediate perforin- and Fas-independent veto activity even in an 8-h clonal deletion assay. We conclude that ABM veto activity does not require the two primary pathways of cell-mediated death.

IL-7 increases both thymic-dependent and thymic-independent T-cell regeneration after bone marrow transplantation

Thymic-dependent differentiation of bone marrow (BM)-derived progenitors and thymic-independent antigen-driven peripheral expansion of mature T cells represent the 2 primary pathways for T-cell regeneration. These pathways are interregulated such that peripheral T-cell expansion is increased in thymectomized versus thymus-bearing hosts after bone marrow transplantation (BMT). This study shows that this interregulation is due to competition between progeny of these 2 pathways because depletion of thymic progeny leads to increased peripheral expansion in thymus-bearing hosts. To test the hypothesis that competition for growth factors modulates the magnitude of antigen-driven peripheral expansion during immune reconstitution in vivo, a variety of T-cell active cytokines were administered after BMT. Of the cytokines (interleukins) tested (IL-3, IL-12, IL-6, IL-2, and IL-7), IL-2 modestly increased peripheral expansion in the face of increasing numbers of thymic emigrants, whereas IL-7 potently accomplished this. This report also demonstrates that the beneficial effect of IL-7 on immune reconstitution is related to both increases in thymopoiesis as well as a direct increase in the magnitude of antigen-driven peripheral expansion. Therefore, the administration of exogenous IL-7, and to a lesser extent IL-2, abrogates the down-regulation in antigen-driven peripheral expansion that occurs in thymus-bearing hosts after BMT. These results suggest that one mechanism by which T-cell-depleted hosts may support antigen-driven T-cell expansion in vivo is via an increased availability of T-cell-active cytokines to support clonal expansion.

Early suppressive effects of chemotherapy on recovery of bone marrow megakaryocyte precursors: possible relationship to platelet recovery

This study utilized a recently developed culture and quantitation system to detect megakaryocyte precursors in CD34+ bone marrow cells from normal donors and breast cancer patients treated with 5-fluorouracil, leucovorin, adriamycin and cyclophosphamide (FLAC). Bone marrow was obtained from patients before and then after their first cycle of FLAC once blood cell counts had recovered. CD34+ cells were isolated and placed in liquid culture with growth factors to stimulate proliferation and lineage commitment. Absorbance values from an enzyme-linked immunosorbent assay were used to quantitate expression of platelet glycoprotein GPIIb/IIIa. There was an increase in absorbance with increasing numbers of cells seeded per culture that was associated with an increase in the number of megakaryocyte lineage cells produced. After 10 days in liquid culture, absorbance values for expression of GPIIb/IIIa from 2,000 normal donor and pre-chemotherapy CD34+ marrow cells were > or = 1.0. Absorbance values from cultures of post-chemotherapy CD34+ cells from four patients were similar to values from pre-chemotherapy CD34+ cells. In contrast, absorbance values from cultures of post-chemotherapy CD34+ cells from two other patients were low (absorbance < 0.5). Low absorbance values for GPIIb/IIIa expression indicate that megakaryocyte production from those CD34+ cells was reduced. Both of those patients developed prolonged thrombocytopenia and platelet nadirs of less than 20,000/microl during FLAC chemotherapy. In contrast, only one out of four patients whose cultures of post-chemotherapy CD34+ cells had absorbance values > or = 1.0 developed platelet nadirs less than 20,000/microl. These results suggest that low platelet nadirs and delayed platelet recovery may be associated with suppressive effects of chemotherapy on recovery of megakaryocyte precursors.

Thrombopoietin and chemokine mRNA expression in patient post-chemotherapy and in vitro cytokine-treated marrow stromal cell layers

CD34(+) cells and megakaryocyte progenitors were lower in marrow from patients after hematological recovery from the first cycle of 5-fluorouracil, leucovorin, adriamycin, cyclophosphamide (FLAC) chemotherapy plus PIXY321 (GM-CSF/interleukin 3; IL-3 hybrid) than in FLAC + GM-CSF or pre-FLAC marrows. Marrow stromal layers, an in vitro model of the marrow microenvironment, express a combination of stimulatory and inhibitory factors that modulate hematopoietic progenitor cell proliferation and differentiation. The TaqMan assay and quantitative reverse transcriptase-polymerase chain reaction were used to measure monocyte chemoattractant protein-1 (MCP-1), melanoma stimulatory growth activity, and monokine inducible by interferon-gamma (Mig) (inhibitory chemokines for primitive or megakaryocyte progenitors) mRNA levels in in vitro PIXY and GM-CSF-treated and patient post-FLAC marrow stromal layers. Chemokine mRNA was increased after in vitro GM-CSF and to a lesser extent after PIXY treatment. MCP-1 mRNA levels were fivefold higher in FLAC + PIXY than in FLAC + GM-CSF layers, and Mig mRNA was elevated in FLAC + GM-CSF layers. Thrombopoietin (TPO), insulin-like growth factor I (IGF-I), and IGF-II (stimulatory factors for primitive and megakaryocyte progenitors) mRNA were also measured. TPO mRNA levels were 30% lower in GM-CSF and PIXY-pretreated than in control layers with no decrease in IGF mRNA. TPO mRNA in stromal layers of patients who developed grade 3 thrombocytopenia (platelets < 20 x 10(9)/l) during the third cycle of FLAC was only 24% of levels in stromal layers of marrow from other post-FLAC patients. Results demonstrate that patient and in vitro treatment had modulatory effects on TPO and chemokine mRNA expression in marrow stromal layers.

Bacterial lipopolysaccharide, TNF-alpha, and calcium ionophore under serum-free conditions promote rapid dendritic cell-like differentiation in CD14+ monocytes through distinct pathways that activate NK-kappa B

To facilitate the study of signaling pathways involved in myeloid dendritic cell (DC) differentiation, we have developed a serum-free culture system in which human CD14+ peripheral blood monocytes differentiate rapidly in response to bacterial LPS, TNF-alpha, or calcium ionophore (CI). Within 48-96 h, depending on the inducing agent, the cells acquire many immunophenotypical, morphological, functional, and molecular properties of DC. However, there are significant differences in the signaling pathways used by these agents, because 1) LPS-induced, but not CI-induced, DC differentiation required TNF-alpha production; and 2) cyclosporin A inhibited differentiation induced by CI, but not that induced by LPS. Nevertheless, all three inducing agents activated members of the NF-kappaB family of transcription factors, including RelB, suggesting that despite differences in upstream elements, the signaling pathways all involve NF-kappaB. In this report we also demonstrate and offer an explanation for two observed forms of the RelB protein and show that RelB can be induced in myeloid cells, either directly or indirectly, through a calcium-dependent and cyclosporin A-sensitive pathway.

An immunoablative regimen of fludarabine and cyclophosphamide prevents fully MHC-mismatched murine marrow graft rejection independent of GVHD

The prevention of graft rejection in the setting of nonmyeloablative transplant approaches might be mediated by chemotherapy-induced host immunoablation and by the graft-promoting effects of graft-versus-host disease (GVHD). To evaluate whether host immunoablation alone might allow for alloengraftment, we developed an F1-into-parent murine marrow rejection model using host preparative regimens of lethal total body irradiation (TBI; 950 cGy), sublethal irradiation (600 cGy), or combinations of fludarabine (Flu) and cyclophosphamide (Cy). A preparative regimen selectivity index (SI) was calculated to determine whether host lymphocytes were preferentially depleted relative to myeloid cells (SI = number of host myeloid/number host T lymphoid cells remaining after preparative regimen administration). Saline-treated recipients were assigned an SI value of 1.0. Recipients of lethal TBI had reduced myeloid cells relative to T cells (SI = 0.6). In contrast, all Flu/Cy regimens preferentially depleted host T cells: recipients of Flu (100 mg/kg per day)/Cy (50 mg/kg per day) for 10 days (SI = 28.1); recipients of Flu (100 mg/kg per day)/Cy (100 mg/kg per day) for 10 days (SI = 64.1); and recipients of Flu (100 mg/kg per day)/Cy (50 mg/kg per day) for 19 or 27 days (SI = 74.6). The 10-day regimen of Flu/Cy (50 mg/kg per day) did not severely reduce host T cell numbers, nor did it prevent F1 marrow rejection (<1% chimerism, n = 14). In contrast, the 10-day regimen of Flu/Cy (100 mg/kg per day) reduced T-cell numbers below that of lethal TBI recipients and prevented F1 marrow rejection (11.4% chimerism, n = 15); donor chimerism was predominant in lymphoid cells and was stable through day 240 post-BMT. Additionally, the 19- or 27-day regimen of Flu/Cy, which most selectively depleted host T cells, also prevented F1 marrow rejection (6.3% chimerism, n = 15). These results therefore demonstrate that optimized Flu-containing, immunoablative preparative regimens can prevent fully MHC-disparate marrow rejection independent of GVHD.

Prolonged CD4 depletion after sequential autologous peripheral blood progenitor cell infusions in children and young adults

Administration of mobilized peripheral blood progenitor cells (PBPCs) after high-dose chemotherapy rapidly restores multilineage hematopoiesis, but the ability of such products to restore lymphocyte populations remains unclear. In this report, we evaluated immune reconstitution in a series of patients treated with sequential cycles of high-dose chemotherapy, followed by autologous PBPC infusions (median CD34(+) cell dose 7.2 x 10(6) cells/kg [range 2-29.3]). Although patients experienced rapid reconstitution of B cells and CD8(+) T cells, we observed CD4 depletion and diminished immune responsiveness in all patients for several months after completion of therapy. Mature CD4(+) T cells contained within the grafts did not appear to contribute substantially to immune reconstitution because CD4 counts did not differ between recipients of unmanipulated T-cell replete infusions versus CD34 selected, T-cell-depleted infusions. Rather, at 12 months after therapy, total CD4 count was inversely proportional to age (rho = -0.78, P =.04), but showed no relationship to CD34 cell dose (rho = -0.42, P =.26), suggesting that age-related changes within the host are largely responsible for the limited immune reconstitution observed. These results demonstrate that in the autologous setting, the infusion of large numbers of PBPCs is not sufficient to restore T-cell immune competence and emphasize that specific approaches to enhance immune reconstitution are necessary if immune-based therapy is to be used to eradicate minimal residual disease after autologous PBPC transplantation. (Blood. 2000;96:754-762)

Th2 and Tc2 cells in the regulation of GVHD, GVL, and graft rejection: considerations for the allogeneic transplantation therapy of leukemia and lymphoma

Allogeneic stem cell transplantation (SCT) represents a curative treatment option for patients with leukemia and lymphoma. T lymphocytes contained in the allograft mediate a graft-versus-leukemia (GVL) effect and prevent graft rejection; however, T cells also initiate graft-versus-host disease (GVHD). Identification of T cell populations which mediate a GVL effect and prevent rejection with reduced GVHD will likely improve transplantation outcome. T cells exist in four functionally-defined populations, the CD4+, Th1/Th2 and CD8+, Tc1/Tc2 subsets. Th1-type CD4 cells primarily secrete type I cytokines (IL-2 and IFN-gamma), whereas Th2 cells secrete type II cytokines (IL-4, IL-5, and IL-10). Similarly, the CD8+ Tc1 and Tc2 cells differentially secrete the type I and type II cytokines, respectively. In addition to cytokine secretion, Tc1 and Tc2 populations mediate cytolytic effects, with Tc1 cells utilizing both perforin- and fas-based killing pathways, whereas Tc2 cells primarily utilize perforin-mediated cytolysis. In murine transplantation models of graft rejection, GVHD, and GVL effects, we have evaluated such functional T cell subsets for their ability to differentially mediate and regulate transplantation responses. These studies demonstrate that donor Th2 cells do not initiate acute GVHD, and can regulate the GVHD mediated by unmanipulated donor T cells without impairing alloengraftment. Additional experiments have shown that allospecific donor Tc2 cells result in reduced GVHD, and mediate a significant GVL effect. Thirdly, we have demonstrated that non-host reactive Tc2 cells with veto-like activity can potently abrogate marrow rejection independent of GVHD. Together, these results demonstrate that functionally-defined donor Th2 and Tc2 populations play an important role in the regulation of GVHD, the prevention of graft rejection, and the mediation of GVL effects, and suggest that utilization of Th2 and Tc2 cells in clinical allogeneic SCT may have potential for improving treatment outcome.

Suppression of T cell function: a potential role for transcriptional repressor ICER

In this article, we review the inducible cAMP early repressor (ICER) and its possible critical involvement in modulation of T cell responsiveness by its capacity to transcriptionally attenuate interleukin-2 (IL-2) gene expression. It seems clear that the failure to produce the IL-2 is an important determinant of anergy induction. It is important that the CD28-responsive element (CD28RE), a composite DNA binding element consisting of NFAT and cyclic AMP-responsive (CRE)-like motifs in position of -160 of IL-2 promoter has the high affinity for ICER binding as well as NFAT/ICER complex formation. Moreover, CD28RE with adjacent DNA sequences was also shown to be essential for conferring anergy in T lymphocytes. Because ICER does not possess a transactivation domain required for the recruitment of CBP/p300, the binding of ICER to CD28RE and/or composite motifs containing CRE-like DNA motifs may lead to uncoupling of CBP/p300 thus extinguishing IL-2 expression as well as expression of numerous other cytokines and chemokines.

Phase I and pharmacokinetic study of farnesyl protein transferase inhibitor R115777 in advanced cancer

PURPOSE

To determine the maximum-tolerated dose, toxicities, and pharmacokinetic profile of the farnesyl protein transferase inhibitor R115777 when administered orally bid for 5 days every 2 weeks.

PATIENTS AND METHODS

Twenty-seven patients with a median age of 58 years received 85 cycles of R115777 using an intrapatient and interpatient dose escalation schema. Drug was administered orally at escalating doses as a solution (25 to 850 mg bid) or as pellet capsules (500 to 1300 mg bid). Pharmacokinetics were assessed after the first dose and the last dose administered during cycle 1.

RESULTS

Dose-limiting toxicity of grade 3 neuropathy was observed in one patient and grade 2 fatigue (decrease in two performance status levels) was seen in four of six patients treated with 1,300 mg bid. The most frequent clinical grade 2 or 3 adverse events in any cycle included nausea, vomiting, headache, fatigue, anemia, and hypotension. Myelosuppression was mild and infrequent. Peak plasma concentrations of R115777 were achieved within 0.5 to 4 hours after oral drug administration. The elimination of R115777 from plasma was biphasic, with sequential half-lives of about 5 hours and 16 hours. There was little drug accumulation after bid dosing, and steady-state concentrations were achieved within 2 to 3 days. The pharmacokinetics were dose proportional in the 25 to 325 mg/dose range for the oral solution. Urinary excretion of unchanged R115777 was less than 0.1% of the oral dose. One patient with metastatic colon cancer treated at the 500-mg bid dose had a 46% decrease in carcinoembryonic antigen levels, improvement in cough, and radiographically stable disease for 5 months.

CONCLUSION

R115777 is bioavailable after oral administration and has an acceptable toxicity profile. Based upon pharmacokinetic data, the recommended dose for phase II trials is 500 mg orally bid (total daily dose, 1, 000 mg) for 5 consecutive days followed by 9 days of rest. Studies of continuous dosing and studies of R115777 in combination with chemotherapy are ongoing.

fas-mediated lysis of chronic lymphocytic leukaemia cells: role of type I versus type II cytokines and autologous fasL-expressing T cells

Given the known role of the fas cytolytic pathway in B-cell regulation, we evaluated whether fas-fasL interactions might induce chronic lymphocytic leukaemia (CLL) cell death. De novo CLL cells expressed a low level of surface fas, and were not lysed by fasL-bearing cells. CLL cells cultured in media containing the type I cytokines interleukin (IL)-12 or interferon (IFN)-alpha had increased fas expression, and were readily lysed by fasL-bearing cells. In contrast, the type II cytokine IL-4 did not increase CLL cell fas, and abrogated type I cytokine-induced fas up-regulation. With prolonged culture, IL-4 exposed CLL cells expressed an intermediate level of fas; however, such CLL cells were resistant to fas-mediated lysis. These results indicate that IL-4 inhibits fas-mediated killing of CLL cells at the level of both fas receptor expression and post-receptor events. Additionally, we have defined in vitro culture conditions which generate fasL-bearing T cells from CLL patients; such T cells efficiently mediated fas-based lysis of autologous fas-positive CLL cells. We therefore conclude that type I and type II cytokines differentially regulate the fas pathway in CLL cells, and that a combination of type I cytokines and fasL-expressing T cells may represent a new approach to the immunotherapy of CLL.

Calcium ionophore-treated myeloid cells acquire many dendritic cell characteristics independent of prior differentiation state, transformation status, or sensitivity to biologic agents

We previously reported that treatment of human peripheral blood monocytes or dendritic cells (DC) with calcium ionophore (CI) led to the rapid (18 hour) acquisition of many characteristics of mature DC, including CD83 expression. We therefore investigated whether less-mature myeloid cells were similarly susceptible to rapid CI activation. Although the promyelocytic leukemia line HL-60 was refractory to cytokine differentiation, CI treatment induced near-uniform overnight expression of CD83, CD80 (B7.1), and CD86 (B7. 2), as well as additional characteristics of mature DC. Several cytokines that alone had restricted impact on HL-60 could enhance CI-induced differentiation and resultant T-cell sensitizing capacity. In parallel studies, CD34(pos) cells cultured from normal donor bone marrow developed marked DC-like morphology after overnight treatment with either rhCD40L or CI, but only CI simultaneously induced upregulation of CD83, CD80, and CD86. This contrasted to peripheral blood monocytes, in which such upregulation could be induced with either CI or rhCD40L treatment. We conclude that normal and transformed myeloid cells at many stages of ontogeny possess the capacity to rapidly acquire many properties of mature DC in response to CI treatment. This apparent ability to respond to calcium mobilization, even when putative signal-transducing agents are inoperative, suggests strategies for implementing host antileukemic immune responses.

Calcium mobilization in human myeloid cells results in acquisition of individual dendritic cell-like characteristics through discrete signaling pathways

We have shown previously that calcium ionophore (CI) treatment of various myeloid origin cells results in rapid acquisition of properties associated with mature, activated dendritic cells. These properties include increased CD83 and costimulatory molecule expression, tendencies to form dendritic processes, loss of CD14 expression by monocytes, and typically an enhanced capacity to sensitize T lymphocytes to Ag. We here analyze the intracellular signaling pathways by which CI induces acquisition of such properties. Thapsigargin, which raises intracellular Ca2+ levels by antagonizing its sequestration, induced immunophenotypic and morphologic changes that paralleled CI treatment. CI-induced activation was broadly attenuated by the Ca2+ chelating compound EGTA and by calmodulin antagonists trifluoperazine dimaleate and W-7. However, antagonists of signaling pathways downstream to calmodulin displayed more selective inhibitory effects. Calcineurin antagonists cyclosporin A and the FK-506 analogue, ascomycin, diminished costimulatory molecule and CD83 expression, as well as formation of dendritic processes in CI-treated myeloid cells, and strongly attenuated the T cell allosensitizing capacity of CI-treated HL-60 cells. These calcineurin antagonists displayed minimal effect on CI-induced CD14 down-regulation in monocytes. In contrast, the calmodulin-dependent protein kinase antagonists, K252a and KT5926, while displaying only modest effects on CI-induced costimulatory molecule and CD83 expression, strongly blocked CD14 down-regulation. These results are consistent with a Ca2+-dependent mechanism for CI-induced differentiation of myeloid cells, and indicate that multiple discrete signaling pathways downstream to calcium mobilization and calmodulin activation may be essential in regulating this process.

Post-chemotherapy and cytokine pretreated marrow stromal cell layers suppress hematopoiesis from normal donor CD34+ cells

Marrow stromal layers were used to investigate the potential role of negative regulators produced by the marrow microenvironment as one potential cause of hematopoietic suppression after chemotherapy and cytokines. Stromal layers were established from marrow of normal or prechemotherapy donors and breast cancer patients after hematological recovery from one cycle of 5-fluorouracil, leucovorin, doxorubicin, and cyclophosphamide and GM-CSF or PIXY321 (GM-CSF/IL-3 fusion protein). Normal donor CD34+ cells were placed in contact with stromal layers, and the number of colony-forming units for granulocytes and macrophages (CFU-GM) was determined. There were 25-79% fewer CFU-GM in post-chemotherapy stromal layer cocultures than in no chemotherapy cocultures. With neutralizing antibody to TNF-alpha the number of CFU-GM in no chemotherapy and post-chemotherapy stromal cocultures was, respectively, 96 +/- 7% (n = 5) and 142 +/- 8% (n = 5) of the number with no antibody treatment. PIXY321 and GM-CSF pretreated stromal layers also suppressed production of CFU-GM. Anti-TNF-alpha promoted an increase in CFU-GM numbers from GM-CSF, but not PIXY321, pretreated stromal cocultures. The results demonstrate that post-chemotherapy marrow stromal layers were deficient in supporting in vitro hematopoiesis and suggest that negative regulators induced by chemotherapy and cytokines may be one cause for this defect.

CD8+ T cells of Tc2 phenotype mediate a GVL effect and prevent marrow rejection

Donor T cells mediate both beneficial and detrimental immune reactions in the setting of allogeneic BMT (alloBMT). T cells mediate the GVL effect and prevent marrow rejection, but also induce GVHD. In an attempt to favorably influence the balance of these allogeneic responses, we have evaluated the effect of donor CD4+, Th1/Th2 and CD8+, Tc1/Tc2 functional T cell subsets in murine marrow transplantation models. Our studies have identified the CD8+ Tc2 population (which is a cytolytic effector secreting the type II cytokines IL-4, IL-5, and IL-10) as a subset capable of mediating the GVL effect and preventing marrow rejection with reduced GVHD. We have also shown that the Tc2 subset can be generated in humans. These studies indicate that administration of donor CD8+ T cells of Tc2 phenotype represents a strategy for improving allo BMT outcome.

5-fluorouracil-mediated thymidylate synthase induction in malignant and nonmalignant human cells

Thymidylate synthase (TS, EC 2.1.1.45) is an important target enzyme for the fluoropyrimidines used in cancer chemotherapy. Studies have documented a 2- to 4-fold induction of TS protein following 5-fluorouracil (5-FU) treatment of malignant cells. We measured the effect that 5-FU exposure had on TS protein expression in nonmalignant human breast (MCF-10 and HBL-100), colorectal (ATCC Co18, Co112, and Co33), and bone marrow cells along with malignant breast (MCF-7) and colon (NCI-H630) cells. Twenty-four hours after plating, cells were treated with 0.01 to 10 microM of 5-FU for a period of 24 hr. TS was quantitated by Western immunoblot using monoclonal antibody TS106. Absolute levels of TS in nonmalignant cells were substantially lower than in the malignant lines, ranging from approximately 40% in HBL-100 cells to less than 10% in the colon lines. An approximately two-fold induction in the level of TS was found for all cell lines examined, and there was a strong dependence on 5-FU exposure concentration in free TS levels of MCF-WT, and total TS levels of H630-WT, normal bone marrow, and MCF-10 cells. The induction of TS following 5-FU exposure is a generally observed phenomenon in both malignant and nonmalignant cells, suggesting that a selective means for inhibiting this induction may be critical for the development of alternative therapeutic strategies using 5-FU and the antifolate TS inhibitors.

Thymic function in young/old chimeras: substantial thymic T cell regenerative capacity despite irreversible age-associated thymic involution

Age-associated thymic involution results in a diminished capacity to regenerate T cell populations, although the magnitude of this effect is unknown. In this report, thymic function was studied in aged vs. young adult mice after lethal irradiation and administration of T cell-depleted bone marrow (BM) from young mice. Abnormalities observed in aged thymi (reduced thymocyte numbers, histologic abnormalities) were not reversed by administration of young BM via bone marrow transplantation (BMT), but aged thymi displayed a normal thymocyte subset distribution and appropriately deleted MIs-reactive T cells after BMT. Aged BMT recipients regenerated significantly reduced numbers of splenic T cells compared to young recipients and showed increased peripheral expansion of thymic emigrants since a higher proportion of BM-derived T cells expressed a memory phenotype in aged vs. young BMT recipients. Because peripheral expansion of thymic emigrants could substantially increase the number of thymic progeny present in the spleen, we sought to measure thymic T cell regenerative capacity after BMT in a setting devoid of peripheral expansion. To do this, TCR-transgenic (Tg+) T cell-depleted BM was administered to aged and young recipients lacking antigen specific for the Tg+ TCR. Aged recipients regenerated approximately 50 % of the TCR Tg+ cells regenerated in young BMT recipients, providing evidence that even very aged thymi retain the capacity to regenerate significant numbers of mature T cell progeny. Therefore, thymic function is reduced with aged but it is not lost, suggesting that therapeutic approaches to enhance thymic function may be successful even in very aged hosts.

Non-host-reactive donor CD8+ T cells of Tc2 phenotype potently inhibit marrow graft rejection

Donor CD8+ T cells capable of host reactivity inhibit marrow graft rejection, but also generate graft-versus-host disease (GVHD). To evaluate whether the Tc1- and Tc2-type subsets of CD8 cells might inhibit rejection without host reactivity, we established an F1 into-parent murine bone marrow transplant model. Donor Tc1 and Tc2 cells were generated that preferentially secreted type I or type II cytokines; both subsets possessed potent cytolytic function, and clonally deleted host-type allospecific precursor CTL in vitro. B6 hosts receiving 950 cGy irradiation did not reject the donor marrow (F1 chimerism of 78.6%; n = 10), whereas hosts receiving 650 cGy rejected the donor marrow (3.8% chimerism; n = 8). At 650 cGy irradiation, the addition of Tc2 cells to the F1 marrow resulted in extensive F1 chimerism (70.8%) in 8 of 8 recipients; in contrast, alloengraftment was not consistently observed in mice receiving Tc1 cells or unmanipulated CD8 cells. Furthermore, when the preparative regimen was further reduced to 600 cGy, only hosts receiving the Tc2-type cells did not reject the F1 marrow. We conclude that Tc2 cells potently inhibit marrow graft rejection without inducing an alloaggressive response and that non-host-reactive Tc2 cells therefore facilitate engraftment across genetic barriers with reduced GVHD.

Restoration of T-cell homeostasis after T-cell depletion

T-cell homeostasis appears to be maintained throughout much of normal adult life independent of de-novo production from hematopoietic stem cells via thymopoiesis. Instead, peripheral mechanisms are generally sufficient to maintain normal T-cell number, function and adequate TCR repertoire diversity in healthy hosts. Studies of T-cell regeneration in animals, however, have shown that full restoration of T-cell homeostasis after profound T-cell depletion is primarily dependent upon thymopoiesis. In this setting, thymic-deficient hosts have prolonged reductions in total T-cell number, restricted TCR repertoire diversity, and limited immunocompetence. In humans, age-related reductions in thymic regenerative capacity as early as young adulthood result in incomplete restoration of T-cell homeostasis after T-cell depletion.

Thymic aging and T-cell regeneration

Studies of T-cell regeneration using animal models have consistently shown the importance of the thymus for T-cell regeneration. In humans, recent studies have shown that declines in thymic T-cell regenerative capacity begins relatively early in life, resulting in a limited capacity for T-cell regeneration by young adulthood. As a result, adult humans who experience profound T-cell depletion regenerate T cells primarily via relatively inefficient thymic-independent pathways, resulting in prolonged CD4 depletion, CD4+ and CD8+ subset alterations, limited TCR repertoire diversity and a propensity for activation induced cell death. These limitations in T-cell regeneration have significant clinical implications in the setting of HIV infection and bone marrow transplantation and may also contribute to immunologic abnormalities associated with normal aging. While the mechanisms responsible for thymic aging are not well understood, current evidence suggests that changes within the thymus itself are primary, while age-related changes in marrow T-cell progenitors and inhibitory factors within the extrathymic host milieu contribute to a lesser extent. The development of therapies which can reverse thymic aging are critical for improving outcome in clinical settings of T-cell depletion, and could potentially improve immunologic function in normal aged hosts.

Constraints on CD4 recovery postchemotherapy in adults: thymic insufficiency and apoptotic decline of expanded peripheral CD4 cells

To examine the mechanisms of CD4 reconstitution in an adult population, lymphocyte repopulation was assessed following dose-intense chemotherapy in 25 breast cancer patients, ages 33 to 69 years. Chemotherapy resulted in a greater than 60% reduction in total CD4 T cells and, in particular, a greater than 90% loss of the CD45RA+ CD4 cells. CD4 recovery was protracted, achieving less than 50% of pretreatment levels after 12 to 14 months. Two facets of the CD4 recovery were notable. First, generation of CD45RA+ CD4 cells played only a minor role in the first year, suggesting that thymic production was not the main route of CD4 regeneration. Indeed, recovery of CD45RA+ CD4 cell levels remained limited in half of the patients even after 2 years. Second, expansion of the mature peripheral CD4 cells (CD45RO+) remaining after chemotherapy was the main source of early CD4 repopulation, peaking at 3 to 6 months postchemotherapy. This expansion was limited in duration, however, and was followed by a secondary decline, such that the total CD45RO+ CD4 levels at 9 to 12 months were lower than at 6 months. When stimulated by mitogens, an increased susceptibility to apoptosis was observed in postchemotherapy CD4 cells as compared with those from normal donors. The elevated expression of markers such as HLA-DR during chemotherapy and for several months postchemotherapy is consistent with the presence of an activated T-cell population. CD4 apoptotic frequency correlated with the frequency of HLA-DR expression on T cells. Thus, CD4 recovery is constrained in adults by a limited thymic regenerative capacity and by an increased susceptibility to apoptosis within the expanding peripheral CD4 population.

In vitro generation of allospecific human CD8+ T cells of Tc1 and Tc2 phenotype

We have previously shown that allospecific murine CD8+ T cells of the Tc1 and Tc2 phenotype could be generated in vitro, and that such functionally defined T-cell subsets mediated a graft-versus-leukemia (GVL) effect with reduced graft-versus-host disease (GVHD). To evaluate whether analogous Tc1 and Tc2 subsets might be generated in humans, CD8+ T cells were allostimulated in the presence of either interleukin-12 (IL-12) and transforming growth factor-beta (TGF-beta) (Tc1 culture) or IL-4 (Tc2 culture). Tc1-type CD8 cells secreted the type I cytokines IL-2 and interferon gamma (IFN-gamma), whereas Tc2-type cells primarily secreted the type II cytokines IL-4, IL-5, and IL-10. Both cytokine-secreting populations effectively lysed tumor targets when stimulated with anti-T-cell receptor (TCR) antibody; allospecificity of Tc1- and Tc2-mediated cytolytic function was demonstrated using bone marrow-derived stimulator cells as targets. In addition, both Tc1 and Tc2 subsets were capable of mediating cytolysis through the fas pathway. We therefore conclude that allospecific human CD8+ T cells of Tc1 and Tc2 phenotype can be generated in vitro, and that these T-cell populations may be important for the mediation and regulation of allogeneic transplantation responses.

A role for TGFbeta1 in langerhans cell biology. Further characterization of the epidermal Langerhans cell defect in TGFbeta1 null mice

Previous studies of TGFbeta1 null (-/-) mice indicated that the epidermis was devoid of Langerhans cells (LC) and that the LC deficiency was not secondary to the inflammation that is the dominant feature of the -/- phenotype (Borkowski, T.A., J.J. Letterio, A.G. Farr, and M.C. Udey. 1996. J. Exp. Med. 184:2417-2422). Herein, we demonstrate that dendritic cells could be expanded from the bone marrow of -/- mice and littermate controls. Bone marrow from -/- mice also gave rise to LC after transfer into lethally irradiated recipients. Thus, the LC defect in TGFbeta1 null mice does not result from an absolute deficiency in bone marrow precursors, and paracrine TGFbeta1 production is sufficient for LC development. Several approaches were used to assess the suitability of -/- skin for LC localization. A survey revealed that although a number of cytokine mRNAs were expressed de novo, mRNAs encoding proinflammatory cytokines known to mobilize LC from epidermis (IL-1 and TNFalpha) were not strikingly overrepresented in -/- skin. In addition, bone marrow-derived LC populated full-thickness TGFbeta1 null skin after engraftment onto BALB/c nu/nu recipients. Finally, the skin of transgenic mice expressing a truncated loricrin promoter-driven dominant-negative TGFbeta type II receptor contained normal numbers of LC. Because TGFbeta1 signaling in these mice is disrupted only in keratinocytes and the keratinocyte hyperproliferative component of the TGFbeta1 -/- phenotype is reproduced, these results strongly suggest that the LC defect in TGFbeta1 null mice is not due to an epidermal abnormality but reflects a requirement of murine LC (or their precursors) for TGFbeta1.

Suppressive effects of recombinant human monokine induced by IFN-gamma (rHuMig) chemokine on the number of committed and primitive hemopoietic progenitors in liquid cultures of CD34+ human bone marrow cells

Studies in this report investigated potential hemopoietic suppressive effects of human monokine induced by IFN-gamma (HuMig), a CXC chemokine that is chemotactic for activated lymphocytes. rHuMig was purified from Trichoplusia ni cells after infection with a recombinant baculovirus. The recombinant protein was added to liquid cultures of CD34+ human marrow cells stimulated with IL-3 alone or with both IL-3 and either insulin-like growth factor II (IGF-II) or stem cell growth factor (SCF). The number of committed progenitors, colony-forming units for granulocytes and macrophages (CFU-GM), and primitive progenitors, long term culture-initiating cells (LTC-IC) derived from liquid cultures of CD34+ cells, was determined. rHuMig abrogated the IGF-II-dependent enhancement of CFU-GM and long term culture-initiating cell numbers. Additional studies demonstrated that in liquid cultures of CD34+ cells both rHuMig and IFN-inducible protein-10, another CXC chemokine that is related to HuMig, inhibited the production or expansion of CFU-GM. For a subset of marrows, rHuMig also abrogated SCF enhancement of CFU-GM numbers in cultures of CD34+ cells stimulated with both IL-3 and SCF. These studies are the first to demonstrate that rHuMig can act as a negative regulator of in vitro hemopoiesis, that both rHuMig and IP-10 can suppress an increase in the number of committed progenitors from CD34+ cells, and that chemokines can abrogate hemopoietic stimulatory effects of IGF-II.

Suppressive effects of recombinant human monokine induced by IFN-gamma (rHuMig) chemokine on the number of committed and primitive hemopoietic progenitors in liquid cultures of CD34+ human bone marrow cells

Studies in this report investigated potential hemopoietic suppressive effects of human monokine induced by IFN-gamma (HuMig), a CXC chemokine that is chemotactic for activated lymphocytes. rHuMig was purified from Trichoplusia ni cells after infection with a recombinant baculovirus. The recombinant protein was added to liquid cultures of CD34+ human marrow cells stimulated with IL-3 alone or with both IL-3 and either insulin-like growth factor II (IGF-II) or stem cell growth factor (SCF). The number of committed progenitors, colony-forming units for granulocytes and macrophages (CFU-GM), and primitive progenitors, long term culture-initiating cells (LTC-IC) derived from liquid cultures of CD34+ cells, was determined. rHuMig abrogated the IGF-II-dependent enhancement of CFU-GM and long term culture-initiating cell numbers. Additional studies demonstrated that in liquid cultures of CD34+ cells both rHuMig and IFN-inducible protein-10, another CXC chemokine that is related to HuMig, inhibited the production or expansion of CFU-GM. For a subset of marrows, rHuMig also abrogated SCF enhancement of CFU-GM numbers in cultures of CD34+ cells stimulated with both IL-3 and SCF. These studies are the first to demonstrate that rHuMig can act as a negative regulator of in vitro hemopoiesis, that both rHuMig and IP-10 can suppress an increase in the number of committed progenitors from CD34+ cells, and that chemokines can abrogate hemopoietic stimulatory effects of IGF-II.

Pathways of T-cell regeneration in mice and humans: implications for bone marrow transplantation and immunotherapy

Much of our understanding of the immunobiology of bone marrow transplantation (BMT) has come from studies in young adult mice reconstituted with T-cell-depleted bone marrow after lethal irradiation. Recent evidence indicates, however, that the applicability of conclusions drawn from this model to human BMT may be limited. While mice retain essentially normal thymic function well past sexual maturity, humans show significant age-related declines in thymic function relatively early in life. Therefore, thymic-deficient mice may provide a more accurate model for study of the immunobiology of BMT. T-cell regeneration in thymic-deficient mice occurs primarily via antigen-driven expansion of mature peripheral T cells resulting in limited immune competence due to quantitative deficiencies in T-cell number and severe restriction in the diversity of the regenerated T-cell receptor (TCR) repertoire. Similarly, immune reconstitution in adult humans after BMT is marked by quantitative T-cell deficiencies, especially in the CD4+ subset, and loss of TCR diversity. Taken together, prevailing evidence suggests that thymic function is suboptimal in most BMT recipients, and that thymic-independent pathways of T-cell regeneration are generally limited in their ability to restore host immune competence. New strategies to enhance thymic function in man after BMT would hold great therapeutic potential.

Distinctions between CD8+ and CD4+ T-cell regenerative pathways result in prolonged T-cell subset imbalance after intensive chemotherapy

Rapid recovery of CD4+ T cells after intensive chemotherapy is limited by an age-dependent decline in thymopoiesis. Here we sought to determine whether similar limitations exist for CD8+ T-cell regeneration. After intensive chemotherapy, CD8+ T cells had a faster effective doubling time than CD4+ T cells (median, 12.6 v 28.2 days, P < .05). Accordingly, at 3 months posttherapy, mean CD8+ T-cell number had returned to baseline, whereas mean CD4+ T-cell number was only 35% of pretherapy values (P < .05). These differences were primarily due to very rapid expansion of CD8+CD57+ and CD8+CD28- subsets. At 3 months posttherapy, there was no relationship between age and CD8+ T-cell number (R = -.02), whereas CD4+ T-cell number was inversely related to age (R = -.66) and there were no discernible differences in CD8+ recovery among patients with or without thymic enlargement, whereas CD4+ recovery was enhanced in patients with thymic enlargement after chemotherapy (P < .01). Therefore thymic-independent pathways of T-cell regeneration appear to rapidly regenerate substantial numbers of CD8+, but not CD4+ T cells, resulting in prolonged T-cell subset imbalance after T-cell depletion. These inherent distinctions between CD4+ v CD8+ T-cell regeneration may have significant implications for immunotherapeutic strategies undertaken to eradicate minimal residual neoplastic disease after cytoreductive chemotherapy.