A pilot study evaluating the safety and CD34+ cell mobilizing activity of escalating doses of plerixafor in healthy volunteers

This study evaluated the safety and CD34+ cell mobilizing activity of escalating doses of plerixafor in healthy volunteers. Three cohorts of six subjects received two different doses of plerixafor separated by at least 2 weeks to allow for adequate pharmacodynamic wash-out. The following dosing cohorts were evaluated: 0·24 and 0·32 mg/kg (Cohort 1); 0·32 and 0·40 mg/kg (Cohort 2); and 0·40 and 0·48 mg/kg (Cohort 3). Circulating CD34+ cells were measured 0, 2, 4, 6, 8, 10, 12, 14, 18 and 24 h after each dose. Blood colony-forming units were measured at baseline and 6 h after each dose. Common adverse events were diarrhoea, injection site erythema, perioral numbness, sinus tachycardia, headache, nausea, abdominal distention and injection site pain. No dose limiting toxicities occurred. When higher doses of plerixafor were administered, there was a trend towards higher peak CD34+ counts and CD34+ area under the curves, although these differences did not achieve statistical significance, perhaps due to intra-subject variability. Together, these data show that the higher doses of plerixafor evaluated in this study are reasonably safe and suggest that a larger study should be performed to definitively answer whether increased numbers of CD34+ cell are mobilized with higher doses of plerixafor.

Repeated PR1 and WT1 peptide vaccination in Montanide-adjuvant fails to induce sustained high-avidity, epitope-specific CD8+ T cells in myeloid malignancies

BACKGROUND

We previously showed that vaccination with one dose of PR1 and WT1 peptides induces transient anti-leukemia immunity. We hypothesized that maintenance of a sustained anti-leukemia response may require frequent boost injections.

DESIGN AND METHODS

Eight patients with myeloid malignancies were enrolled in this phase II study, and 6 completed 6 injections of PR1 and WT1 peptides in Montanide-adjuvant with GM-CSF, every two weeks.

RESULTS

Both high- and low-avidity PR1 or WT1-specific CD8(+) T cells were detected in all evaluable patients after the first vaccine dose. Repeated vaccination led to selective deletion of high avidity PR1- and WT1-specific CD8(+) T cells and was not associated with significant reduction in WT1-expression. Additional boosting failed to increase vaccine-induced CD8(+) T-cell frequencies further and in all patients the response was lost before the 6(th) dose. PR1- or WT1-specific CD8(+) T cells were not detected in bone marrow samples, excluding their preferential localization to this site. Following a booster injection three months after the 6(th) vaccine dose, no high-avidity PR1 or WT1-specific CD8(+) T cells could be detected, whereas low-avidity T cells were readily expanded.

CONCLUSIONS

These data support the immunogenicity of PR1 and WT1 peptide vaccines. However, repeated delivery of peptides with Montanide-adjuvant and GM-CSF leads to rapid loss of high-avidity peptide-specific CD8(+) T cells. These results may offer an explanation for the lack of correlation between immune and clinical responses observed in a number of clinical trials of peptide vaccination. New approaches are needed to induce long-term high-avidity memory responses against leukemia antigens.

Alemtuzumab treatment of intermediate-1 myelodysplasia patients is associated with sustained improvement in blood counts and cytogenetic remissions

PURPOSE

Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis and progression to leukemia. Clinical and experimental evidence suggests an immune-mediated pathophysiology in some patients, in whom immunosuppressive therapy (IST) with horse antithymocyte globulin (h-ATG) and cyclosporine (CsA) can be effective. Because of the toxicities associated with h-ATG/CsA, we investigated an alternative regimen with alemtuzumab in MDS.

PATIENTS AND METHODS

We conducted a nonrandomized, off-label, pilot, phase I/II study of alemtuzumab monotherapy in patients with MDS who were judged likely to respond to IST based on the following criteria: HLA-DR15-negative patients whose age plus the number of months of RBC transfusion dependence (RCTD) was less than 58; and HLA-DR15-positive patients whose age plus RCTD was less than 72. In total, 121 patients with MDS were screened, of whom 32 met eligibility criteria to receive alemtuzumab 10 mg/d intravenously for 10 days. Primary end points were hematologic responses at 3, 6, and 12 months after alemtuzumab.

RESULTS

Seventeen (77%) of 22 evaluable intermediate-1 patients and four (57%) of seven evaluable intermediate-2 patients responded to treatment with a median time to response of 3 months. Four of seven evaluable responders with cytogenetic abnormalities before treatment had normal cytogenetics by 1 year after treatment. Five (56%) of nine responding patients evaluable at 12 months had normal blood counts, and seven (78%) of nine patients were transfusion independent.

CONCLUSION

Alemtuzumab is safe and active in MDS and may be an attractive alternative to ATG in selected patients likely to respond to IST.

Lenalidomide-induced upregulation of CD80 on tumor cells correlates with T-cell activation, the rapid onset of a cytokine release syndrome and leukemic cell clearance in chronic lymphocytic leukemia

BACKGROUND

In chronic lymphocytic leukemia lenalidomide causes striking immune activation, possibly leading to clearance of tumor cells. We conducted this study to investigate the mechanism of action of lenalidomide and the basis for its unique toxicities in chronic lymphocytic leukemia.

DESIGN AND METHODS

Patients with relapsed chronic lymphocytic leukemia were treated with lenalidomide 20 mg (n=10) or 10 mg (n=8) daily for 3 weeks on a 6-week cycle. Correlative studies assessed expression of co-stimulatory molecules on tumor cells, T-cell activation, cytokine levels, and changes in lymphocyte subsets.

RESULTS

Lenalidomide upregulated the co-stimulatory molecule CD80 on chronic lymphocytic leukemia and mantle cell lymphoma cells but not on normal peripheral blood B cells in vitro. T-cell activation was apparent in chronic lymphocytic leukemia, weak in mantle cell lymphoma, but absent in normal peripheral blood mononuclear cells and correlated with the upregulation of CD80 on B cells. Strong CD80 upregulation and T-cell activation predicted more severe side effects, manifesting in 83% of patients as a cytokine release syndrome within 8-72 h after the first dose of lenalidomide. Serum levels of various cytokines, including tumor necrosis factor-alpha, increased during treatment. CD80 upregulation on tumor cells correlated with rapid clearance of leukemic cells from the peripheral blood. In contrast, neither the severity of the cytokine release syndrome nor the degree of T-cell activation in vitro correlated with clinical response.

CONCLUSIONS

Upregulation of CD80 on tumor cells and T-cell activation correlate with unique toxicities of lenalidomide in chronic lymphocytic leukemia. However, T-cell activation appears to be dispensable for the drug's anti-tumor effects. This provides a rationale for combinations of lenalidomide with fludarabine or alemtuzumab.

Treatment of severe aplastic anemia with a combination of horse antithymocyte globulin and cyclosporine, with or without sirolimus: a prospective randomized study

BACKGROUND

We hypothesized that the addition of sirolimus to standard horse antithymocyte globulin (h-ATG) and cyclosporine (CsA) would improve response rates in severe aplastic anemia, due to its complementary and synergistic properties to cyclosporine A.

DESIGN AND METHODS

To test this hypothesis, we conducted a prospective randomized study comparing hATG/CsA/sirolimus to standard h-ATG/CsA. A total of 77 patients were treated from June 2003 to November 2005; 35 received h-ATG/CsA/sirolimus and 42 h-ATG/CsA. The two groups were well matched demographically and in blood counts prior to therapy. The primary end-point was hematologic response rate at 3 months, defined as no longer meeting the criteria for severe aplastic anemia. The study was powered to show a superior hematologic response rate of h-ATG/CsA/sirolimus compared to standard h-ATG/CsA.

RESULTS

The overall response rate at 3 months was 37% for h-ATG/CsA/sirolimus and 50% for h-ATG/CsA and at 6 months 51% for h-ATG/CsA/sirolimus and 62% for h-ATG/CsA. After a planned interim analysis of 30 evaluable patients in each arm, accrual to the h-ATG/CsA/sirolimus arm was closed, as the conditional power for rejecting the null hypothesis was less than 1%. The rate of relapse, clonal evolution, and survival (secondary outcomes) did not differ significantly between patients treated with the two different regimens.

CONCLUSIONS

Despite a theoretical rationale for its use, sirolimus did not improve the response rate in patients with severe aplastic anemia when compared to standard h-ATG/CsA.

Leukemia-associated antigen-specific T-cell responses following combined PR1 and WT1 peptide vaccination in patients with myeloid malignancies

We describe the safety and immunogenicity of a combined vaccine of 2 leukemia-associated antigenic peptides, PR1 and WT1. Eight patients with myeloid malignancies received one subcutaneous dose each of PR1 and WT1 vaccines in Montanide adjuvant, with granulocyte-macrophage colony-stimulating factor. Patients were reviewed weekly for 4 weeks to monitor toxicity and immunologic responses. Toxicity was limited to grades 1 to 2. Using peptide/HLA-A 0201 tetramers and intracellular interferon-gamma staining, CD8(+) T cells against PR1 or WT1 were detected in 8 of 8 patients after a single vaccination. To monitor the kinetics of vaccine-induced CD8(+) T-cell responses and disease regression after vaccination, absolute PR1 and WT1(+)CD8(+) T-cell numbers and WT1 expression were studied weekly after vaccination. Responses occurred as early as 1 week after vaccination. After vaccination, the emergence of PR1 or WT1(+)CD8(+) T cells was associated with a decrease in WT1 mRNA expression as a marker of minimal residual disease, suggesting a vaccine-driven antileukemia effect. Conversely, loss of response was associated with reappearance of WT1 transcripts (P < .01). This is the first demonstration that a combined PR1 and WT1 vaccine is immunogenic. These results support further studies of combination immunization strategies in leukemia patients.

Identification of RGS5 as a tumor-associated antigen expressed in a broad range of human malignancies and recognized by antigen specific cytotoxic T cells

2569

Background: Identification of tumor-associated antigens (TAA) have resulted in the development of therapeutic vaccines for the treatment of cancer. We applied an integrated functional genomics approach to identify TAA in malignant tissues of patients with renal cell carcinoma (RCC). Methods: A comparative DNA chip analysis of tumor and the corresponding non-malignant tissue from patients with RCC followed by sequencing of peptides bound to the HLA-class I molecules by mass spectrometry was applied to identify novel TAA in RCC. To confirm the immunogenicity of identified epitopes cytotoxic T lymphocytes (CTL) were generated using dendritic cells (DC). Results: RGS5 was found to be overexpressed in 16 of 29 analyzed RCC (5.7–29.9 fold) as compared to non-malignant renal tissue. Two peptides derived from RGS5 binding to either HLA-A*02 or 03 were identified. RGS5 was previously shown to be expressed in pericytes and promote tumor angiogenesis. Using RT-PCR analysis we found that RGS5 is expressed on a broad variety of tumor cells including RCC, colorectal, breast and ovarian cancer, malignant melanoma and multiple myeloma as well as in acute and chronic leukemias making this protein an interesting candidate for the development of vaccination strategies to target the tumor cells and the tumor vessels. CTL that were induced using the RGS5 peptides lysed autologous DC pulsed with the cognate peptide or transfected with in vitro transcribed RGS5 RNA as well as HLA-matched tumor cell lines. The specificity and HLA restriction was confirmed using blocking monoclonal antibodies and in cold-target inhibition assays. We next utilized DC transfected with RGS5 RNA to generate specific CTL. Using this approach we confirmed the processing and presentation of the identified peptides by malignant cells. These CTL lysed tumor cells in antigen specific manner while sparing non-malignant cells. In an ongoing vaccine trial RGS5 peptides could safely be given to RCC patients resulting in the induction of peptide specific CTL responses. Conclusions: Our results demonstrate that RGS5 is a novel tumor rejection antigen expressed in a wide range of malignancies that can be applied to target malignant cells and tumor angiogenesis.

[Table: see text]

Improved Outcome for Peripheral Blood Stem Cell Transplantation for Advanced Primary Myelodysplastic Syndrome

Stem cell transplantation for myelodysplastic syndrome (MDS) is characterized by high transplant-related mortality (TRM), especially in older patients and those with more advanced disease. Outcome after peripheral blood stem cell transplantation (PBSCT) may be superior to earlier results with bone marrow transplantation. Forty-three patients (aged 12-73 years; median, 49 years) received an HLA-identical sibling donor PBSCT. Twenty three patients aged < or =55 years without prohibitive comorbidity received myeloablative total body irradiation-based conditioning, followed by a T cell-depleted PBSCT and delayed add-back of donor lymphocytes. Older patients or those with comorbidities (n = 20) received reduced-intensity conditioning and an unmanipulated PBSCT. Thirty-seven (86%) had advanced disease (refractory anemia with excess blasts [n = 9], refractory anemia with excess blasts in transformation [n = 6], acute myelogenous leukemia [n = 13], or treatment-related MDS [n = 9]); 6 had low-risk MDS (refractory anemia or refractory anemia with ringed sideroblasts). The median follow-up was 18 months (range, 5-89 months). Actuarial probabilities of 3-year overall survival (OS), disease-free survival, relapse, and TRM were 64%, 59%, 26%, and 23%, respectively, for 34 primary MDS patients. The best results were in 19 patients younger than 50 years of age undergoing myeloablative PBSCT (actuarial probabilities of OS, disease-free survival, relapse, and TRM were 81%, 72%, 22%, and 7%, respectively). Although outcomes for all stages of primary MDS were improved, that for therapy-related MDS remained dismal, with 11% OS, because of a high relapse rate (89%).

Recombinant humanized anti-IL-2 receptor antibody (daclizumab) produces responses in patients with moderate aplastic anemia

In contrast to severe aplastic anemia (sAA), the appropriate management of patients with moderate pancytopenia is unclear. In this study, we examined the efficacy of a humanized monoclonal antibody recognizing interleukin-2 receptor (daclizumab), which has proven to be a successful immunosuppressive agent in solid organ and bone marrow transplantation. We treated 17 patients with moderate aplastic anemia (mAA) with 1 mg/kg every 2 weeks for 3 months. mAA was defined as depression of 2 of the 3 blood counts: absolute neutrophil count 1200/mm3 or less, platelet count 70,000/mm3 or less, hemoglobin level 8.5 g/dL or lower, and absolute reticulocyte count 60,000/mm3 or less. The primary end point of our protocol was a hematologic response in at least one affected peripheral blood value. Daclizumab had little toxicity. Six of the 16 (38%) evaluable patients responded to treatment. Two patients with previously chronic disease showed complete return of normal counts, which were sustained for more than 2 years following treatment. Four patients had single-lineage responses. Two previously transfusion-dependent patients became transfusion independent; one patient with many neutropenia-related infections had a normal neutrophil count following treatment. Daclizumab appears safe; its efficacy in this pilot protocol suggests that expanded study of this monoclonal antibody in immune-mediated bone marrow failure syndrome is warranted.

Inhibitors of the Plasmodium falciparum parasite aspartic protease plasmepsin II as potential antimalarial agents

Malaria is a very serious infectious disease against which the currently available drugs are loosing effectiveness. The main problem is the emergence and the spreading of resistant parasite strains. New treatments are needed in order to regain control over the disease. Drug discovery efforts towards this goal are likely to be more successful, if they focus towards novel mechanisms of action. Such efforts will result in drugs that are functionally and structurally different from the existing drugs and therefore will overcome existing resistances. Here we focus on the aspartic protease plasmepsin II, which is a promising new drug target. We review the drug discovery efforts that were published in the literature on this enzyme, and we present the compounds synthesized at Actelion Pharmaceuticals Ltd.

Clinical and immunologic assessment of patients with psoriasis in a randomized, double-blind, placebo-controlled trial using recombinant human interleukin 10

BACKGROUND

In several open-label studies, recombinant human interleukin 10 (rhIL-10), a type 2 anti-inflammatory cytokine, has been reported to improve psoriasis, a disease characterized by type 1 cytokine inflammation.

OBJECTIVE

To evaluate the safety, efficacy, and immunologic parameters in individuals with psoriasis treated with rhIL-10.

DESIGN AND INTERVENTION

Patients received rhIL-10 (20 micro g/kg) or placebo subcutaneously 3 times weekly for 12 weeks in a randomized, double-blind manner.

SETTING AND PATIENTS

National Institutes of Health Clinical Center in Bethesda. Twenty-eight patients with moderate-to-severe psoriasis as defined by a Psoriasis Area Severity Index (PASI) score of 10 or higher.

MAIN OUTCOME MEASURE

The primary clinical end point was the mean percentage change in the PASI score comparing baseline and week 12 scores. Intracellular cytokine production by peripheral blood mononuclear cells (PBMCs) was measured by flow cytometry.

RESULTS

There was no significant difference in the mean percentage change in the PASI score from baseline to week 12 between the rhIL-10-treated group and control patients (17% vs 13% improvement, respectively; P =.69), although a modest trend toward improvement in patients receiving rhIL-10 was documented at both the 6- and 8-week points. Interestingly, proinflammatory and type 1 cytokine production by PBMCs progressively declined in the rhIL-10-treated patients during the entire 12-week study period.

CONCLUSIONS

Treatment with rhIL-10 resulted in only temporary clinical improvement in psoriasis, despite sustained systemic decreases in proinflammatory and type 1 cytokine production. These data suggest that immunotherapy that decreases the ratio of systemic type 1 and type 2 cytokine production does not necessarily lead to improvement of type 1 cytokine-mediated disease.

Endothelin receptor antagonists: structures, synthesis, selectivity and therapeutic applications

Endothelin (ET) was discovered in 1988 and is the most potent vasoconstrictive peptide known to date. It exists in three isoforms (ET-1 to ET-3) and acts on two endothelin receptor subtypes, the endothelin-A (ET(A))-receptor and the endothelin-B (ET(B))-receptor. Endothelin receptor antagonists are novel therapeutics in clinical development for different cardiovascular, cerebrovascular, and renal diseases. Several different structural classes of endothelin receptor antagonists have been discovered within the last decade, starting from peptidic- and peptidomimetic structures to small organic molecules suitable as therapeutics for oral administration. Focussing on the small organic molecules, the different structural classes of ET-receptor antagonists are described with respect to synthesis, structure-activity-relationships, receptor-subtype-selectivity profile, and where possible, intended therapeutic indications.

Concurrent paclitaxel and radiation in the treatment of locally advanced head and neck cancer

PURPOSE

To determine the feasibility of an organ preservation regimen consisting of infusional paclitaxel administered concurrently with radiotherapy to patients with locally advanced head and neck squamous cell carcinoma (HNSCC).

PATIENTS AND METHODS

Thirty-three previously untreated patients with stage III or IV tumors were enrolled onto the study. Paclitaxel was administered as a 120-hour continuous infusion every 3 weeks during the course of radiation therapy. Sixteen patients received a paclitaxel dose of 105 mg/m(2), and 17 patients received 120 mg/m(2). Radiation was delivered in a standard format at 1.8 Gy/d to a total dose of 70.2 to 72 Gy.

RESULTS

Three months after therapy, a 76% complete response (CR) at the primary site and a 70% overall CR was achieved. At 36 months, locoregional control was 55.7%, overall survival was 57.8%, and disease-free survival was 51.1%. The median survival duration for all 33 patients was greater than 50 months at the time of this report. Local toxicities including mucositis, dysphagia, and skin reactions were severe but tolerable. All patients retained functional speech, and all but four patients were swallowing food 3 months after treatment. Steady-state plasma concentrations for paclitaxel were not achieved during a 120-hour infusion, suggesting a nonlinear process. Tumor volume quantified by pretreatment computerized tomography imaging was associated with likelihood of response and survival.

CONCLUSION

Paclitaxel administered as a 120-hour continuous infusion in combination with radiotherapy is a feasible and promising treatment for patients with advanced HNSCC.

Cutaneous spider nevi in liver cirrhosis: capillary microscopical and hormonal investigations

Nailfold capillary microscopical and hormonal investigations were carried out in 25 patients with cirrhosis of the liver and in 20 age- and sex-matched controls. Several structural and functional capillary microscopical parameters were significantly different between the group of cirrhotics as a whole and the controls; no capillaroscopic feature helped to distinguish cirrhotics with spiders from those without. Serum estradiol and total testosterone were comparable in cirrhotics and controls; free serum testosterone was reduced in male cirrhotics, particularly in cirrhotics with spider nevi. The estradiol/free testosterone ratio was highest in male cirrhotics with spiders. Cirrhosis, thus, leads to both structural and functional effects on the cutaneous capillary system whether or not spider nevi are present. The presence of spider nevi is accompanied by an increased serum estradiol/free testosterone ratio in male cirrhotics. It remains to be determined whether the hormonal alterations described do indeed play a role in spider nevi formation.