Biomedical subjects

James L Murray

Publications and source records attributed to James L Murray.

At least 19 recordsLinked to original sources

PubMed2006

Internalized Pseudomonas exotoxin A can exploit multiple pathways to reach the endoplasmic reticulum.

Receptor-mediated internalization to the endoplasmic reticulum (ER) and subsequent retro-translocation to the cytosol are essential sequential processes required for the intoxication of mammalian cells by Pseudomonas exotoxin A (PEx). The toxin binds the alpha2-macroglobulin receptor/low-density lipoprotein receptor-related protein. Here, we show that in HeLa cells, PEx recruits a proportion of this receptor to detergent-resistant microdomains (DRMs). Uptake of receptor-bound PEx involves transport steps both directly from early endosomes to the trans-Golgi network (TGN) independently of Rab9 function and from late endosomes to the TGN in a Rab9-dependent manner. Furthermore, treatments that simultaneously perturb both Arf1-dependent and Rab6-dependent retrograde pathways show that PEx can use multiple routes to reach the ER. The Rab6-dependent route has only been described previously for cargo with lipid-sorting signals. These findings suggest that partial localization of PEx within DRM permits a choice of trafficking routes consistent with a model that DRM-associated toxins reach the ER on a lipid-dependent sorting pathway whilst non-DRM-associated PEx exploits the previously characterized KDEL receptor-mediated uptake pathway. Thus, unexpectedly, an ER-directed toxin with a proteinaceous receptor shows promiscuity in its intracellular trafficking pathways, exploiting routes controlled by both lipid- and protein-sorting signals.

3T3 Cells↗

PubMed2006

Prostate tumor cells infected with a recombinant influenza virus expressing a truncated NS1 protein activate cytolytic CD8+ cells to recognize noninfected tumor cells.

Many viral oncolytic approaches against cancer are based on the ability of specific viruses to replicate in tumors expressing components of the constitutively activated Ras/mitogen-activated protein kinase (MAPK) pathways and/or inhibited or dysregulated alpha/beta interferon (IFN-alpha/beta) response pathways. A major issue when considering these approaches is their applicability to tumors that lack activated Ras. To identify the effector mechanisms activated by oncolytic viruses, we investigated inhibition of proliferation of the prostate cancer line LNCap by the recombinant TR-NS1 influenza A virus, a genetically attenuated influenza A/PR8/34 virus expressing a truncated nonstructural protein (NS1) of 126 amino acids. LNCap cells lack constitutively activated MAPK, extracellular signal-regulated kinase (ERK), and p38 and are resistant to death by IFN-alpha. Truncation of the NS1 protein of influenza viruses is known to result in viral attenuation due to a reduced ability of the NS1 to inhibit the IFN-alpha/beta response. Infection with TR-NS1 virus rapidly activated ERK-1 more than ERK-2 in LNCap cells. Importantly, TR-NS1 virus infection transiently inhibited cell proliferation and induced apoptosis in LNCap cells. Addition of peripheral blood mononuclear cells (PBMC) and interleukin 12 (IL-12) to TR-NS1 virus-infected LNCap cells (TR-NS1-LNCap) resulted in faster elimination of TR-NS1-LNCap cells compared with LNCap cells. Moreover, TR-NS1-LNCap cells induced IFN-gamma in PBMC. The levels of IFN-gamma were amplified by IL-12. TR-NS1-LNCap cells also induced tumor-lytic cytotoxic T lymphocytes (CTL). These CTL lysed noninfected LNCap cells in a CD8-dependent manner. Activation of cellular immunity to tumor cells by viruses is an intriguing effector pathway, which should be especially significant for elimination of human tumors that lack activated Ras.

CD8-Positive T-Lymphocytes↗

PubMed2005

Sensitivity of undifferentiated, high-TCR density CD8+ cells to methylene groups appended to tumor antigen determines their differentiation or death.

CD8(+) cells expressing high numbers of TCR per cell (TCR(hi)) are considered important mediators of antitumor effects. To understand the relationship between TCR density and antigen affinity for TCR in the outcome of stimulation with antigen and differentiation of CTL recognizing tumor antigen, we analyzed perforin induction in ovarian tumor-associated lymphocytes in response to the smallest possible changes in the atomic forces of interaction between antigen and TCR. Stimulating undifferentiated, apoptosis-resistant CD8(+) cells expressing high levels of E75-TCR (TCR(hi)) with variants of the CTL epitope E75, HER-2 (369-377), induced their stepwise differentiation, first to IFN-gamma(+) Perf(-) and to TCR(hi) IFN-gamma(+) Perf(+) cells. Blocking caspase-9 activation at antigen stimulation also enhanced the generation of TCR(hi) Perf(hi) cells, demonstrating that TCR density dictated the pathway of death activated by stimulation with the same agonist. Expansion and differentiation of TCR(hi) Perf(+) CTL required an agonist of optimal CH(2) side chain length, which in this study was equal to two CH(2) groups appended to E75 at the Gly(4) position. Side chains one CH(2) shorter or longer than optimal were either less stimulatory or induced death of TCR(hi) Perf(+) cells. Differentiation of TCR(hi) CD8(+) cells can be finely tuned by synthetic amino acids in the peptide, whose side chains induce small increments in the affinity of the antigen for TCR below the affinity which induce apoptosis.

Antigens, Neoplasm↗

PubMed2005

Rab9 GTPase is required for replication of human immunodeficiency virus type 1, filoviruses, and measles virus.

Rab proteins and their effectors facilitate vesicular transport by tethering donor vesicles to their respective target membranes. By using gene trap insertional mutagenesis, we identified Rab9, which mediates late-endosome-to-trans-Golgi-network trafficking, among several candidate host genes whose disruption allowed the survival of Marburg virus-infected cells, suggesting that Rab9 is utilized in Marburg replication. Although Rab9 has not been implicated in human immunodeficiency virus (HIV) replication, previous reports suggested that the late endosome is an initiation site for HIV assembly and that TIP47-dependent trafficking out of the late endosome to the trans-Golgi network facilitates the sorting of HIV Env into virions budding at the plasma membrane. We examined the role of Rab9 in the life cycles of HIV and several unrelated viruses, using small interfering RNA (siRNA) to silence Rab9 expression before viral infection. Silencing Rab9 expression dramatically inhibited HIV replication, as did silencing the host genes encoding TIP47, p40, and PIKfyve, which also facilitate late-endosome-to-trans-Golgi vesicular transport. In addition, silencing studies revealed that HIV replication was dependent on the expression of Rab11A, which mediates trans-Golgi-to-plasma-membrane transport, and that increased HIV Gag was sequestered in a CD63+ endocytic compartment in a cell line stably expressing Rab9 siRNA. Replication of the enveloped Ebola, Marburg, and measles viruses was inhibited with Rab9 siRNA, although the non-enveloped reovirus was insensitive to Rab9 silencing. These results suggest that Rab9 is an important cellular target for inhibiting diverse viruses and help to define a late-endosome-to-plasma-membrane vesicular transport pathway important in viral assembly.

Animals↗

PubMed2004

Fine specificity of high molecular weight-melanoma-associated antigen-specific cytotoxic T lymphocytes elicited by anti-idiotypic monoclonal antibodies in patients with melanoma.

HLA-A2-restricted CTLs, which lysed high molecular weight (HMW)-melanoma-associated antigen (MAA)(+) melanoma cells, were induced in patients with melanoma immunized with MELIMMUNE, a combination of the murine anti-idiotypic (anti-id) monoclonal antibodies (mAb) MEL-2 and MF11-30 (MW Pride et al., Clin Cancer Res 1998;4:2363.). In the present study we investigated whether CTL epitopes are present in anti-id mAb MF-11-30 and activate T cells to recognize HMW-MAA on melanoma cells. One candidate epitope in the mAb MF11-30 VH chain, VH (3-11), was selected based on the presence of HLA-A2 anchor residues and partial homology with the HMW-MAA epitope, HMW-MAA (76-84). Lymphocytes from HLA-A2(+)-immunized patients proliferated to VH (3-11) peptide and to a variant HMW-MAA peptide to a significantly greater extent than autologous lymphocytes stimulated with an irrelevant peptide and lymphocytes from nonimmunized patients. No proliferative response was detected to the wild-type HMW-MAA peptide (76-84). Significant increase in IFN-gamma production but not in interleukin 10 production in response to VH (3-11) and to variant HMW-MAA peptide (76-84) was observed in lymphocytes from the immunized patients. Stimulation of lymphocytes from HLA-A2(+) patients with the two peptides induced CTL, which lysed HMW-MAA(+)/HLA-A2(+) A375SM melanoma cells. This is the first report documenting the presence of immunogenic peptides in a murine anti-id mAb for a defined epitope expressed by a human melanoma-associated antigen. These results may be relevant for development of novel vaccines based on homology between anti-id mAb and tumor-associated antigen amino acid sequences.

Amino Acid Sequence↗

PubMed2004

Yttrium-90 ibritumomab tiuxetan radioimmunotherapy in Richter syndrome.

BACKGROUND: (90)Y ibritumomab tiuxetan is a radioimmunotherapeutic construct that is reported to be an effective treatment for patients with lymphoma. The aim of the current analysis was to evaluate retrospectively the efficacy and safety of (90)Y ibritumomab tiuxetan in patients with Richter syndrome (RS). METHODS: Patients with histologically proven CD20-positive RS and < 25% lymphoma and/or chronic lymphocytic leukemia in the bone marrow were treated. Patients received an imaging dose of (111)In-labeled ibritumomab tiuxetan of 1.6 mg (5.0 mCi of (111)In) intravenously. One week later, they received 0.3 or 0.4 mCi/kg of (90)Y ibritumomab tiuxetan. Rituximab, at a dose of 250 mg/m(2) intravenously, was given immediately before ibritumomab tiuxetan on Days 1 and 8. RESULTS: Seven patients were treated. Their median age was 56 years (range, 44-70 years). The median time to transformation was 7.9 years (range, 0.7-28.4 years). The median number of previous therapies received was five (range, one to seven previous therapies). The median number of previous therapies received for RS was one (range, none to three previous therapies). Six patients were treated previously with hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with methotrexate and cytosine arabinoside. No patient responded to (90)Y ibritumomab tiuxetan therapy. All patients developed disease progression. The median time to disease progression was 41 days (range, 39-89 days). Side effects included hematologic toxicity. Grade 3-4 (according to the second version of the National Cancer Institute Common Toxicity Criteria) thrombocytopenia and neutropenia occurred in 5 patients (71%) and 2 patients (29%), respectively. There was one episode of septic shock in a patient with Grade 4 neutropenia. CONCLUSIONS: (90)Y ibritumomab tiuxetan had no significant antitumor activity and hematologic toxicity was severe in these heavily pretreated patients with RS.

Adult↗

PubMed2004

Ii-Key/HER-2/neu MHC class-II antigenic epitope vaccine peptide for breast cancer.

PURPOSE: Cytotoxic T lymphocytes (CTL)- and T-helper cell-specific, and major histocompatibility complex (MHC) class-I and class-II peptides, respectively, of the HER-2/ neu protein, induce immune responses in patients. A major challenge in developing cancer peptide vaccines is breaking tolerance to tumor-associated antigens which are functionally self-proteins. An adequate CD4+ T-helper response is required for effective and lasting responses. METHODS: Stimulating anti-cancer CD4+ T cell responses by MHC class-II epitope peptides has been limited by their weak potency, at least compared with tight-binding MHC class-I epitope peptides. Previously, a potent T-cell response to a MHC class-II epitope was engineered by coupling the N-terminus of the pigeon cytochrome C [PGCC(95-104)] MHC class-II epitope to the C-terminus of an immunoregulatory segment of the Ii protein (hIi77-81, the Ii-Key peptide) through a polymethylene spacer. RESULTS: In vitro presentation of the MHC class-II epitope to a T hybridoma was enhanced greatly (>250 times). Now, an Ii-Key/HER-2/neu (777-789) MHC class-II epitope hybrid peptide stimulated lymphocytes from both a healthy donor and a patient with metastatic breast carcinoma. The in vitro primary stimulation with the hybrid peptide strongly activated IFN-gamma release, whereas the epitope-only peptide was weakly active. In fact, the hybrid stimulated IFN-gamma release as well as the wild-type peptide when augmented with IL-12; however, the hybrid was comparable to free peptide in stimulating IL-4 release. This pattern is consistent with preferential activation along a non-tolerogenic Th1 pathway. CONCLUSION: Such Ii-Key/MHC class-II epitope hybrid peptides have both diagnostic and therapeutic applications.

Antigens, Differentiation, B-Lymphocyte↗

PubMed2004

Radiolabeled antibody therapy in non-Hodgkins lymphoma: radiation protection, isotope comparisons and quality of life issues.

Anti-CD20 antibodies radiolabeled with I-131 tositumomab (Bexxar) or Y-90-Ibritumomab tiuxetan (Zevalin), are similarly efficacious in treating chemotherapy-refractory non-Hodgkin's lymphoma. The relative merits of both radioimmunoconjugates with respect to practical issues, including radiation exposure risk, the advantages and disadvantages of the respective isotopes and other parameters that could affect a patient's quality of life are also important. I-131-labeled antibody treatment often requires inpatient hospitalization due to the inherent risk of exposure from gamma emissions, and patients and families should follow detailed instructions to prevent undue exposure. Other issues relevant to patients and medical staff include: (1) the need for dosimetry to calculate effective therapeutic doses of I-131-labeled anti-B1 (Bexxar) compared with the lack of correlation of dosimetry with marrow toxicity for IDEC-Y2B8 (Zevalin), (2) determining the acute and long-term toxic effects of each agent, (3) time commitments for nuclear medicine staff and patients along with the relative ease of administration, and (4) cost considerations. A more challenging future issue will be to determine the optimal use of Bexxar and Zevalin alone and in combination in ways that will significantly affect patient outcome without compromising quality of life. The recent demonstration of significant response rates in patients having chemotherapy-refractory Non-Hodgkin's Lymphoma (NHL) using both on I-131- and Y-90-labeled anti-CD20 antibodies with minimal toxicity has stimulated comparison of I-131 tositumomab (Bexxar) and Ibritumomab tiuxetan (Zevalin) in terms of radiation safety requirements, the advantages and disadvantages of both radionuclides, and quality-of-life (QOL) issues. Therefore, in this review, we attempt to compare the relative merits of (Bexxar and Zevalin) and address important practical considerations that may influence patient and physician choices regarding treatment using these agents.

Antibodies, Monoclonal↗

PubMed2004

Stimulation of cells from a non-invaded and an invaded lymph node with a HER-2+ tumor with peptides corresponding to T-cell epitopes E75 and G89 induced expansion of central memory cells (TCM) from the metastasis-negative lymph nodes.

Breast cancer metastasizes from the primary site to the axillary lymph nodes (LN). It is unknown whether tumor metastasis abolishes or enhances the ability of LN cells to develop a specific response to the Ag expressed by the tumor, and whether an immune response to the same Ag is present in the tumor-free LN. We stimulated lymphocytes from a metastasis negative (Met-) and a metastasis positive (Met+) LN, invaded by a HER-2+ tumor, from the same patient, with HER-2 peptides E75 (369-377) and G89 (776-778). E75 define a CTL epitope presented by HLA-A2, while G89 define a CD4+ cell recognized epitope. Met- LN responded to E75+G89 with higher expansion of E75 TCR+ CD45RO+ CCR7- (CCR7-) and E75-TCR+ CD45RO+ CCR7+ (CCR7+) cells than Met+ LN. Stimulation with E75+G89 induced a significant increase in CCR7+ cells in Met- LN compared with Met+ LN. The levels of IFN-alpha and IL-15 were higher in Met- LN cultures stimulated with E75+G89 than in Met+ LN cultures. This increase did not correlate with the levels of induction of IFN-gamma, IL-4, and IL-10. The finding of higher expansion of Ag specific CCR7+ cells and of differentiation to CCR7- cells, which define the TCM and TEM subsets respectively, in Met- LN, by G89 is novel for tumor systems. This may have implications for preventative vaccination strategies for breast and ovarian cancer.

Breast Neoplasms↗

PubMed2003

Phase I and II study of exisulind in combination with capecitabine in patients with metastatic breast cancer.

PURPOSE: We studied the safety and clinical activity of exisulind in combination with capecitabine in 35 patients with metastatic breast cancer (MBC). PATIENTS AND METHODS: All patients had received previous anthracycline and taxane chemotherapies. Two dose levels of exisulind were explored, 125 and 250 mg orally bid as continuous daily therapy, concomitant with capecitabine 2,000 mg/m2 for 14 days in 21-day cycles. In the phase I study, the dose-limiting toxicities were hand-foot syndrome and diarrhea. The 125-mg bid dose was selected for phase II testing. RESULTS: The most common nonhematologic grade 2 to 3 adverse events were hand-foot syndrome (57%) and fatigue (48%). The most frequent grade 2 to 3 laboratory abnormality was granulocytopenia. No death, unexpected adverse events, or cumulative toxicity were encountered. One complete and four partial responses were achieved (objective response rate, 16%) in the 31 patients assessable for response. The median duration of response was 31 weeks; three patients experienced stable disease longer than 26 weeks. Overall clinical benefit (complete response, partial response, or stable disease > 26 weeks) was 23%. Fourteen specimens were available for immunohistochemical assessment of phosphodiesterase-5 isoenzyme (PDE-5) and PDE-2 expression, which are the targets of exisulind. Eighty percent of tumors showed some expression of PDE-5 in the invasive cancer cells including 35% that showed moderate or strong staining. PDE-2 showed moderate or strong staining in 78% of tumors. There was no apparent association between tumor response and staining intensity. CONCLUSION: Exisulind (125 mg orally bid) in combination with capecitabine is well tolerated and the combination has anticancer activity similar to that of capecitabine alone in heavily pretreated patients with MBC.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2003

Lipid bilayer simulations of CXCR4 with inverse agonists and weak partial agonists.

CXCR4 is a G protein-coupled receptor (GPCR) that has multiple critical functions in normal and pathologic physiology that include regulation of the metastatic behavior of mammary carcinoma, and utilization as a coreceptor for infection by T-tropic strains of human immunodeficiency virus-1. Molecular dynamic simulations of the rhodopsin-based homology model of CXCR4 were performed in a solvated lipid bilayer to reproduce the microenvironment of this integral membrane protein. The amino acids in CXCR4 necessary for interaction with an inverse agonist, T140, and a weak partial agonist, AMD3100, identified by alanine scanning mutants, were spatially consistent when computationally docked. Whereas T140 binds residues in extracellular domains and regions of the hydrophobic core proximal to the cell surface, amino acids in the central hydrophobic core are critical to binding of AMD3100. The physical localization of T140 binding to CXCR4 by biochemical analyses corroborated the molecular and computational approaches. The structural basis for the interaction of T140 and AMD3100 with CXCR4 confirms that the mechanisms used by these agents are different. This complementary utilization of molecular, physical, and computation analysis provides a powerful approach to elucidate GPCR conformation.

Amino Acid Substitution↗

PubMed2003

Clinical studies of vaccines targeting breast cancer.

Many clinical studies have been undertaken to assess the therapeutic potential of vaccination and have included a large variety of cancer immunogens. Most of these studies involved patients with metastatic cancer, which is characterized by the most aggressive malignant cells, the longest-lasting disease, and the failure of all standard cytotoxic treatments. The presence of tumor over long periods and the toxicity of previous treatments tend to negatively affect immune responsiveness to tumor antigens presented by the vaccine. In this review, we analyze the ability of past and current vaccine therapies to induce clinical responses in breast cancer. To date, clinical responses have been observed by using vaccines targeting HER-2/neu protein, human telomerase reverse transcriptase, carcinoembryonic antigen, and carbohydrate antigen given after stem cell rescue. The review concludes with a discussion of possible future directions for vaccine development and applications.

Animals↗

PubMed2003

Safety of yttrium-90 ibritumomab tiuxetan radioimmunotherapy for relapsed low-grade, follicular, or transformed non-hodgkin's lymphoma.

PURPOSE: Radioimmunotherapy (RIT) with yttrium-90 ((90)Y)-labeled anti-CD20 antibody ((90)Y ibritumomab tiuxetan; Zevalin, IDEC Pharmaceuticals Corporation, San Diego, CA) has a high rate of tumor response in patients with relapsed or refractory, low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma (NHL). This study presents the safety data from 349 patients in five studies of outpatient treatment with (90)Y ibritumomab tiuxetan. PATIENTS AND METHODS: Patients received rituximab 250 mg/m(2) on days 1 and 8, and either 0.4 mCi/kg (15 MBq/kg) or 0.3 mCi/kg (11 MBq/kg) of (90)Y ibritumomab tiuxetan on day 8 (maximum dose, 32 mCi). Patients were observed for up to 4 years after therapy or until progressive disease. RESULTS: Infusion-related toxicities were typically grade 1 or 2 and were associated with rituximab. No significant organ toxicity was noted. Toxicity was primarily hematologic, with nadir counts occurring at 7 to 9 weeks and lasting approximately 1 to 4 weeks depending on the method of calculation. After the 0.4-mCi/kg dose, grade 4 neutropenia, thrombocytopenia, and anemia occurred in 30%, 10%, and 3% of patients, respectively, and after the 0.3-mCi/kg dose, these grade 4 toxicities occurred in 35%, 14%, and 8% of patients, respectively. The risk of hematologic toxicity increased with degree of baseline bone marrow involvement with NHL. Seven percent of patients were hospitalized with infection (3% with neutropenia) and 2% had grade 3 or 4 bleeding events. Myelodysplasia or acute myelogenous leukemia was reported in five patients (1%) 8 to 34 months after treatment. CONCLUSION: Single-dose (90)Y ibritumomab tiuxetan RIT has an acceptable safety profile in relapsed NHL patients with less than 25% lymphoma marrow involvement, adequate marrow reserve, platelets greater than 100,000 cells/ micro L, and neutrophils greater than 1,500 cells/ micro L.

Adult↗

PubMed2003

A Phase I study of docetaxel plus cyclophosphamide in solid tumors followed by a Phase II study as first-line therapy in metastatic breast cancer.

PURPOSE: In Phase I, the purpose was to determine the maximum tolerated dose and pharmacokinetics of docetaxel plus cyclophosphamide (DC) with and without granulocyte colony-stimulating factor in the treatment of patients with solid tumors. For Phase II, the purpose was to determine the safety and efficacy of this combination as first-line treatment in patients with metastatic breast cancer (MBC). EXPERIMENTAL DESIGN: In Phase I (45 patients), docetaxel was escalated from 60 mg/m(2) to 85 mg/m(2), and cyclophosphamide from 600 mg/m(2) to 800 mg/m(2). Pharmacokinetic evaluation of docetaxel was performed in 19 patients with MBC. In Phase II (34 patients), patients received cyclophosphamide (600 mg/m(2)) followed by docetaxel (75 mg/m(2)), i.v. RESULTS: In Phase I, the dose-limiting toxicity was neutropenia-related events. The maximum tolerated dose for DC was 75 mg/m(2)/700 mg/m(2) in solid tumor patients treated previously and 75 mg/m(2)/800 mg/m(2) for patients not treated previously for MBC. Dose escalation of docetaxel >75 mg/m(2) was not tolerated, despite prophylactic granulocyte colony-stimulating factor treatment. In Phase II, 71% of patients received prior anthracycline therapy. Neutropenic fever requiring i.v. antibiotics occurred in 6 patients (19%). One patient had grade 3 neuropathy. There was no cardiotoxicity. The overall Phase II intent-to-treat objective response rate was 65% (complete responses, 12%). The median overall survival was 22 months, and the median time to progression was 6 months. CONCLUSIONS: DC combination therapy is an active regimen with acceptable toxicity and is appropriate regardless of prior anthracycline therapy. In view of the high activity and lack of cardiotoxicity, this combination warrants additional investigation in early stage breast cancer and in combination with trastuzumab.

Adult↗

PubMed2002

Induction of tumor-reactive CTL by C-side chain variants of the CTL epitope HER-2/neu protooncogene (369-377) selected by molecular modeling of the peptide: HLA-A2 complex.

To design side chain variants for modulation of immunogenicity, we modeled the complex of the HLA-A2 molecule with an immunodominant peptide, E75, from the HER-2/neu protooncogene protein recognized by CTL. We identified the side chain orientation of E75. We modified E75 at the central Ser(5) (E75 wild-type), which points upward, by removing successively the HO (variant S5A) and the CH2-OH (variant S5G). Replacement of the OH with an aminopropyl (CH2)3-NH3 (variant S5K) maintained a similar upward orientation of the side chain. S5A and S5G were stronger stimulators while S5K was a weaker stimulator than E75 for induction of lytic function, indicating that the OH group and its extension hindered TCR activation. S5K-CTL survived longer than did CTL induced by E75 and the variants S5A and S5G, which became apoptotic after restimulation with the inducer. S5K-CTL also recognized E75 endogenously presented by the tumor by IFN-gamma production and specific cytolysis. S5K-CTL expanded at stimulation with E75 or with E75 plus agonistic anti-Fas mAb. Compared with S5K-CTL that had been restimulated with the inducer S5K, S5K-CTL stimulated with wild-type E75 expressed higher levels of E75(+) TCR and BCL-2. Activation of human tumor-reactive CTL by weaker agonists than the nominal Ag, followed by expansion with the nominal Ag, is a novel approach to antitumor CTL development. Fine tuning of activation of tumor-reactive CTL by weak agonists, designed by molecular modeling, may circumvent cell death or tolerization induced by tumor Ag, and thus, may provide a novel approach to the rational design of human cancer vaccines.

Adjuvants, Immunologic↗

PubMed2002

Ibritumomab tiuxetan radioimmunotherapy for patients with relapsed or refractory non-Hodgkin lymphoma and mild thrombocytopenia: a phase II multicenter trial.

Mildly thrombocytopenic patients with relapsed or refractory low-grade non-Hodgkin lymphoma (NHL) have an increased risk of chemotherapy-induced myelosuppression following treatment. The safety and efficacy of radioimmunotherapy with a reduced dose of (90)Y ibritumomab tiuxetan (0.3 mCi/kg [11 MBq/kg]; maximum 32 mCi [1.2 GBq]) was evaluated in 30 patients with mild thrombocytopenia (100-149 x 10(9) platelets/L) who had advanced, relapsed or refractory, low-grade, follicular, or transformed B-cell NHL. The ibritumomab tiuxetan regimen included an infusion of rituximab (250 mg/m(2)) and injection of (111)In ibritumomab tiuxetan (5 mCi [185 MBq]) for dosimetry evaluation, followed 1 week later with rituximab (250 mg/m(2)) and (90)Y ibritumomab tiuxetan (0.3 mCi/kg [11 MBq/kg]). Patients (median age, 61 years; 90% stage III/IV at study entry; 83% follicular lymphoma; and 67% with bone marrow involvement) had a median of 2 prior therapy regimens (range, 1-9). Estimated radiation-absorbed doses were well below the study-defined maximum allowable for all 30 patients. With the use of the International Workshop criteria for NHL response assessment, the overall response rate was 83% (37% complete response, 6.7% complete response unconfirmed, and 40% partial response). Kaplan-Meier estimated median time to progression (TTP) was 9.4 months (range, 1.7-24.6). In responders, Kaplan-Meier estimated median TTP was 12.6 months (range, 4.9-24.6), with 35% of data censored. Toxicity was primarily hematologic, transient, and reversible. The incidence of grade 4 neutropenia, thrombocytopenia, and anemia was 33%, 13%, and 3%, respectively. Reduced-dose ibritumomab tiuxetan is safe and well tolerated and has significant clinical activity in this patient population.

Adult↗

PubMed2002

Phase II study of weekly docetaxel and trastuzumab for patients with HER-2-overexpressing metastatic breast cancer.

PURPOSE: To evaluate the safety and efficacy of weekly docetaxel plus trastuzumab in women with HER-2-overexpressing metastatic breast cancer. Efficacy was correlated with serum HER-2 extracellular domain (ECD) levels. PATIENTS AND METHODS: Thirty women with metastatic breast cancer were treated with weekly docetaxel and trastuzumab as first- or second-line therapy. Both docetaxel 35 mg/m(2)/wk and trastuzumab 2 mg/kg/wk were delivered in 4-week cycles consisting of three weekly treatments followed by 1 week of rest. A loading dose of trastuzumab 4 mg/kg was administered 1 day before the start of the first cycle. RESULTS: The median delivered dose-intensity of docetaxel was 24 mg/m(2)/wk (range, 18 to 27 mg/m(2)/wk). The intent-to-treat overall response rate (ORR) was 63% (95% confidence interval [CI], 44% to 80%). The ORR in patients whose tumors were HER-2-positive by fluorescence in situ hybridization was 67% (16 of 24 patients; 95% CI, 45% to 84%). In patients with elevated serum HER-2 ECD at baseline, the ORR was 76% (95% CI, 53% to 92%), compared with 33% (95% CI, 7% to 70%) in patients with low HER-2 ECD levels (P =.04). Variations in HER-2 ECD concentrations during treatment correlated with response to treatment. Median time to progression was 9 months. Acute toxicity, including myelosuppression, was mild. Fatigue, fluid retention, and excessive tearing became more common with repetitive dosing. CONCLUSION: Weekly docetaxel and trastuzumab is an active combination for treating patients with HER-2-overexpressing metastatic breast cancer. Serum HER-2 ECD testing may be a promising method for monitoring patients on trastuzumab-based therapy.

Adult↗

PubMed2002

Role of CD4 hinge region in GP120 utilization by immunoglobulin domain 1.

Immunoglobulin-like domain 1 of CD4 (D1-CD4) promotes HIV infection by binding the envelope glycoprotein (ENV) and exposing its coreceptor-binding site. To study CD4-ENV-coreceptor interactions, we characterized hybrid receptors having domains 1 and 2 of CD4 (D1D2-CD4) joined to the N-terminus of chemokine receptors CCR5, CXCR4, CXCR2, and DARC. Hybrid receptors showed conserved ENV-coreceptor specificity in cell-cell fusion assays. Although D1D2-CD4-CCR5 was sufficient to permit ENV-mediated fusion, D1-CD4-CCR5 and human D1/mouse D2-CD4-CCR5 lacked CD4 function and binding to a neutralizing antibody mapped to D1-CD4. Chimeric D1D2-CD4 joined to CCR5 revealed that the C-terminal 20 residues of human D2-CD4 are required for efficient ENV-mediated fusion. Mutagenesis of hybrid receptors showed the importance of residues forming D1-D2 CD4 interdomain contacts and hinge region proximal residues. Mutagenesis of WT human CD4 confirmed that residues forming D1-D2 interdomain contacts and hinge-region proximal residues contribute positively to CD4 activity in the full-length receptor.

Amino Acid Sequence↗