Biomedical subjects

L M Weiner

Publications and source records attributed to L M Weiner.

At least 37 records · Page 2Linked to original sources

PubMed2000

Phase I pharmacokinetic trial of perillyl alcohol (NSC 641066) in patients with refractory solid malignancies.

Perillyl alcohol (POH) is a monoterpene with anticarcinogenic and antitumor activity in murine tumor models. Putative mechanisms of action include activation of the transforming growth factor beta pathway and/or inhibition of p21ras signaling, leading to differentiation or apoptosis. In this Phase I trial, 17 patients took POH p.o. three times daily for 14 days of each 28-day cycle. The starting dose of POH was 1600 mg/m2/dose, with escalations to 2100 and 2800 mg/m2/dose in subsequent cohorts. Chronic nausea and fatigue were dose-limiting toxic effects at 2800 mg/m2. Grade 1-2 hypokalemia was common at 2100 and 2800 mg/m2. Although POH could not be detected in plasma, two of its metabolites, dihydroperillic acid (DHPA) and perillic acid (PA), were measured in plasma and urine on days 1 and 15 after the first and last doses of POH, respectively. Both area under the concentration versus time curve and peak plasma concentration (Cmax) values increased with dose and exhibited high intersubject variability. Day 15 DHPA Cmax values ranged from a mean +/- SD of 22.6+/-12 microM at 1600 mg/m2/dose to 42.4+/-15.24 microM at 2800 mg/m2/dose. Corresponding mean +/- SD Cmax values for PA were 433.2+/-245.8 and 774.1+/-439.6 microM. One patient treated at the 2800 mg/m2/dose had markedly prolonged plasma levels of both PA and DHPA and developed grade 3 mucositis. POH treatment did not consistently alter the expression of p21ras, rap1, or rhoA in peripheral blood mononuclear cells obtained from patients treated at the highest dose level. The metabolites PA and DHPA did not change expression or isoprenylation of p21ras in MCF-7 breast or DU145 prostate carcinoma cells at concentrations that exceeded those achieved in patient plasma after POH treatment. We conclude that POH at 1600-2100 mg/m2 p.o. three times daily is well tolerated on a 14-day on/14-day off dosing schedule. Inhibition of p21ras function in humans is not likely to occur after POH administration at safe doses of the present oral formulation.

Administration, Oral↗

PubMed1999

Production and characterization of mice transgenic for the A and B isoforms of human FcgammaRIII.

Fcgamma receptor (FcgammaR) engagement is pivotal for many effector functions of macrophages, polymorphonuclear neutrophils (PMN), and natural killer (NK) cells. Mice transgenic for the A and B isoforms of human (h) FcgammaRIII on macrophages, PMN, and NK cells were constructed to permit the study of mechanisms and potential in vivo strategies to utilize the cytotoxic effector and antigen-presenting functions of cells expressing the hFcgammaR. The present report characterizes the phenotypic and functional expression of hFcgammaRIII in transgenic mice derived by crossing hFcgammaRIIIA and hFcgammaRIIIB transgenic mice. Interleukin-2 (IL-2) induces hFcgammaRIII expression by myeloid cells and their precursors, and these transgenic receptors promote in vitro cytotoxicity and anti-hFcgammaRIII antibody internalization. Splenocytes from untreated and IL-2-treated hFcgammaRIIIA, hFcgammaRIIIB, and hFcgammaRIIIA/B mice exhibited enhanced in vitro cytotoxicity toward HER-2/neu-overexpressing SK-OV-3 human ovarian carcinoma cells when incubated with the murine bispecific mAb 2B1, which has specificity for HER-2/neu and hFcgammaRIII. These results indicate that hFcgammaRIII transgenes are expressed on relevant murine cellular subsets, exhibit inducible up-regulation patterns similar to those seen in humans, and code for functional proteins. hFcgammaRIII transgenic mice exhibiting specific cellular subset expression will permit the examination of strategies designed to enhance hFcgammaRIII-dependent immunological effector functions and will provide a model system in which to evaluate preclinically potential candidate molecules that recognize hFcgammaRIII for the immunotherapy of cancer.

Animals↗

PubMed1999

Isolation and characterization of an anti-CD16 single-chain Fv fragment and construction of an anti-HER2/neu/anti-CD16 bispecific scFv that triggers CD16-dependent tumor cytolysis.

Bispecific antibody (bsAb)-based clinical trials of cancer have been conducted primarily using intact murine monoclonal antibody (mAb)-derived molecules. In some of these trials, toxicity resulting from the interactions of antibody Fc domains with cellular Fc receptors has limited the doses of antibody (Ab) that can be employed. Furthermore, human anti-mouse Ab responses prohibit multiple therapy courses. These factors have decreased the efficacy of the bsAb 2B1, which targets the extracellular domains (ECD) of the HER2/neu protooncogene product and the human FcgammaRIII (CD16). To address these obstacles, we have constructed and characterized a fully human gene-fused bsAb from single-chain Fv (scFv) molecules specific for HER2/neu and CD16. The human anti-CD16 scFv component, NM3E2, was isolated from a human scFv phage display library. As binding of NM3E2 to human neutrophil-associated CD16 decreased in the presence of plasma IgG, we have concluded that NM3E2 recognizes an epitope in the vicinity of the Fc binding pocket. Furthermore, the NM3E2 scFv was found by surface plasmon resonance-based epitope mapping to share an overlapping epitope with the Leu-11c mAb. The human anti-HER2/neu scFv component, C6.5, which was previously isolated from a human scFv phage display library, was employed as fusion partner for the creation of a bispecific scFv (bs-scFv). In the presence of the C6.5 x NM3E2 bs-scFv, peripheral blood lymphocytes promoted significant lysis of human SK-OV-3 ovarian cancer cells overexpressing HER2/neu. Biodistribution studies performed in SK-OV-3 tumor-bearing scid mice revealed that 1% ID/g of 125I-labeled C6.5 x NM3E2 bs-scFv was specifically retained in tumor at 23 h following injection. These results indicated that both scFv components of the bs-scFv retained their function in the fusion protein. This bsAb should overcome some of the problems associated with the 2B1 bsAb. C6.5 x NM3E2 bs-scFv offers promise as a platform for multifunctional binding proteins with potential clinical applications as a result of its human origin, lack of an Fc domain, ease of production, high level of in vitro tumor cell cytotoxicity and highly selective tumor targeting.

Animals↗

PubMed1999

Bispecific antibodies in cancer therapy.

Based upon in vitro and animal studies, a number of Phase I and II clinical trials have been initiated to test whether bispecific antibodies could redirect immune effectors against tumor cells in cancer patients. Recently, results from those trials showed beneficial effects in some patients but it is clear many problems remain to be solved. In addition, molecular engineering approaches are providing new and improved sources of clinically relevant bispecific antibodies.

Antibodies, Bispecific↗

PubMed1999

Paclitaxel in the treatment of esophageal cancer.

Since its introduction, paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has demonstrated significant antitumor activity in epidermoid carcinomas and adenocarcinomas originating in the esophagus. Paclitaxel is the most active single agent available to treat metastatic esophageal cancer. Combinations of paclitaxel and cisplatin enhance response rates, but the addition of 5-fluorouracil to this combination only increases toxicity without notably augmenting clinical benefit. Paclitaxel also has been incorporated into numerous preoperative regimens for patients with potentially resectable esophageal cancer. While the optimal use of this agent remains undefined in the postoperative setting, it is clear that paclitaxel will be incorporated into the next generation of preoperative chemotherapy or combined chemotherapy plus radiotherapy regimens for operable esophageal cancer.

Antineoplastic Agents, Phytogenic↗

PubMed1999

An overview of monoclonal antibody therapy of cancer.

Monoclonal antibody-based therapeutics are beginning to realize the promise that was predicted with the advent of the core technology more than 20 years ago. Antibody-based therapeutics targeting tumor cell surface antigens such as B-cell idiotypes, CD20 on malignant B cells, CD33 on leukemic blasts, and HER2/neu on breast cancer cells have shown efficacy in clinical trials. Multiple antibody-based strategies have shown promising efficacy in recent clinical trials. Unconjugated immunoglobulins directed against CD20 induce partial and complete responses in up to 50% of patients with advanced, indolent non-Hodgkin's lymphoma When such antibodies are conjugated to appropriate radionuclides and administered in therapeutic doses, the proportions of complete and overall responses increase considerably. Conjugates composed of anti-CD33 antibodies and the chemotherapy agent, calicheamicin, show promising activity in patients with relapsed or refractory acute myelogenous leukemia. Treatment of patients with advanced breast cancer using the anti-HER2/neu antibody trastuzumab (Herceptin; Genentech, San Francisco) leads to objective responses in some patients whose tumors overexpress the HER2/neu oncoprotein. These exciting results justify recent enthusiasm for continued efforts to refine existing approaches and to develop new antibody-based strategies to treat human malignancy.

Animals↗

PubMed1999

Monoclonal antibody therapy of cancer.

Monoclonal antibody therapy is beginning to realize its promise. Efficacy has been seen in clinical trials using antibodies that target tumor cell surface antigens such as B-cell idiotypes, CD20 on malignant B cells, CD33 on leukemic blasts, and HER2/neu on breast cancer. Unconjugated immunoglobulins directed against CD20 induce partial and complete responses in up to 50% of patients with advanced, indolent non-Hodgkin's lymphoma. When such antibodies are conjugated to radionuclides, complete and overall response rates increase. Conjugates composed of anti-CD33 antibodies and the chemotherapy agent, calicheamicin, show promising activity in patients with relapsed or refractory acute myelogenous leukemia Treatment of patients with advanced breast cancer using the anti-HER2/neu antibody, trastuzumab (Herceptin; Genentech, San Francisco, CA) leads to objective responses in some patients with overexpression of the HER2/neu oncoprotein. These exciting results provide a basis for further refinement of the existing approaches to develop new antibody-based cancer therapy strategies.

Animals↗

PubMed1998

High dose chemoradiotherapy followed by esophagectomy for adenocarcinoma of the esophagus and gastroesophageal junction: results of a phase II study of the Eastern Cooperative Oncology Group.

BACKGROUND: To assess the toxicity, local response, and survival associated with multimodality therapy in a cooperative group setting, patients with biopsy-proven clinical Stage I or II adenocarcinoma of the esophagus (staged according to 1983 American Joint Committee on Cancer criteria) or gastroesophageal junction were treated with concomitant radiation and chemotherapy followed by esophagectomy. METHODS: Radiotherapy was administered in daily 2-gray (Gy) fractions 5 days a week until a total of 60 Gy was reached. 5-fluorouracil (5-FU) was infused continuously at a dose of 1000 mg/m2/day for 96 hours on Days 2-5 and 28-31. On Day 2, a 10 mg/m2 bolus of mitomycin was injected intravenously. Esophagectomy was performed 4-8 weeks following completion of the radiotherapy. RESULTS: During the 18-month study period (August 1991 through January 1993), 46 eligible patients were accrued from 21 institutions. Eight patients were Stage I and 38 Stage II. Eighty-seven percent of patients (40 of 46) received 6000 centigray (cGy), and all received >5000 cGy. Seventy-eight percent of patients (36 of 46) received >90% of the planned 5-FU dose. Follow-up ranged from 11 to 36 months (median, 22 months). There were eight treatment-related deaths; two were preoperative (from adult respiratory distress syndrome) and six were postoperative. Complete or partial response prior to esophagectomy was observed in 63% of cases, stable disease in 15%, and progression in 20%. Thirty-three patients underwent esophagectomy (transhiatal, n=14; Ivor Lewis, n=16; other, n=3). No tumor was found in the specimens resected from 8 of these 33 patients; this represented a pathologic complete response rate of 17% overall and 24% for those who underwent esophagectomy. Overall median survival was 16.6 months, 1-year survival 57%, and 2-year survival 27%. Survival was significantly worse for patients with circumferential cancers (median, 18.1 months vs. 8.3 months; P <0.05). CONCLUSION: High dose radiation therapy with concurrent 5-FU and mitomycin may be administered to patients with esophageal adenocarcinoma with acceptable morbidity. However, in a cooperative group setting, esophagogastrectomy following intensive chemoradiotherapy is associated with excessive morbidity and mortality. Circumferential tumor growth is a significant adverse prognostic factor.

Adenocarcinoma↗

PubMed1998

Phase I dose escalating trial of hyperfractionated pre-operative chemoradiation for locally advanced rectal cancer.

PURPOSE: To determine the acute toxicity, post-operative complications, pathologic response and extent of downstaging to high dose pre-operative radiation using a hyperfractionated radiation boost and concurrent chemotherapy in a prospective Phase I trial. MATERIALS & METHODS: To be eligible for this study, patients had to have adenocarcinoma of the rectum less than 12 cm from the anal verge with either Stage T4 or T3 but greater than 4 cm or greater than 40% of the bowel circumference. All patients received 45 Gy pelvic radiation (1.8 Gy per fraction). Subsequent radiation was given to the region of the gross tumor with a 2 cm margin. This "boost" treatment was given at 1.2 Gy twice daily to a total dose of 54.6 Gy for Level I, 57 Gy for Level II, and 61.8 Gy for Level III. 5-FU was given at 1g/m2 over 24 hours for a four day infusion during the first and sixth weeks of radiation, with the second course concurrent with the hyperfractionated radiation. Surgical resection was carried out 4-6 weeks following completion of chemoradiation (in curative cases) and additional adjuvant chemotherapy consisting of 5-FU and Leucovorin was given for an additional 4 monthly cycles Days 1 through 5 beginning four weeks post surgery. RESULTS: Twenty-seven patients, age 40-82 (median 61), completed the initial course of chemoradiation and are included in the analysis of toxicity. The median follow-up is 27 months (range 8-68). Eleven patients were treated to a dose of 54.6 Gy, nine patients to 57 Gy, and seven patients to 61.8 Gy. Twenty-one patients had T3 tumors, and six patients T4 tumors. Grade III acute toxicity from chemoradiation included proctitis (5 patients), dermatitis (9), diarrhea (five), leukopenia (1), cardiac (1). Grade IV toxicities included one patient with diarrhea (on dose Level I) and one patient (on dose Level III) with cardiac toxicity (unrelated to radiation). Surgical resection consisted of abdominal perineal resection in 16 and low anterior resection in 7. Four patients did not undergo a curative resection; three initially presented with metastases and one developed metastasis during the pre-operative regimen. Post-operative complications included pelvic or perineal abscess in two (on dose Levels I & II), and delayed wound healing in two (one of whom, on dose Level III, developed perineal wound dehiscence requiring surgical reconstruction). Of the 23 patients who had a curative resection, four manifested pathologic complete responses (17.4%). Thirteen of 23 patients (57%) had evidence of pathologic downstaging and only 1/23 patients (on dose Level I) had a positive resection margin. Of these 23 patients (with a minimum follow-up of 8 months), the patient with positive margins was the only one who developed a local failure (Fisher's Exact p=.04). The 3-year actuarial OS, DFS and LC rates are 82%, 72% and 96%, respectively. Twelve of 13 patients (92% at 3 years) > or = 61 years vs. 5/10 patients (45% at 3 years) < 61 years remained disease-free (log-rank p=0.017). CONCLUSION: This regimen of high dose pre-operative chemoradiation employing a hyperfractionated radiation boost is feasible and tolerable and results in significant downstaging in locally advanced rectal cancer. The vast majority of patients (96%) achieved negative margins, which appears to be a prerequisite for local control (p= 0.04). Older age (> or =61 years) was a significant predictor for improved DFS. This regimen (at dose Level III, 61.8 Gy) is currently being tested in a Phase II setting.

Adenocarcinoma↗

PubMed1998

Increased affinity leads to improved selective tumor delivery of single-chain Fv antibodies.

Mr 25,000 single-chain Fv (scFv) molecules are rapidly eliminated from the circulation of immunodeficient mice, yielding highly specific retention of small quantities of scFv in human tumor xenografts. We postulated that the specific retention of scFv in tumor could be enhanced by engineering significant increases in the affinity of the scFv for its target antigens. Affinity mutants of the human anti-HER2/neu (c-erbB-2) scFv C6.5 were generated by site-directed mutagenesis, which target the same antigenic epitope with a 320-fold range in affinity (3.2 x 10(-7) to 1.0 x 10(-9) M). In vitro, the Kd of each scFv correlated closely with the duration of its retention on the surface of human ovarian carcinoma SK-OV-3 cells overexpressing HER2/neu. In biodistribution studies performed in scid mice bearing established SK-OV-3 tumors, the degree and specificity of tumor localization increased significantly with increasing affinity. At 24 h after injection, tumor retention of the highest affinity scFv was 7-fold greater than that of a mutant with 320-fold lower affinity for HER2/neu. Because the rapid renal clearance of scFv may blunt the impact of improved affinity on tumor targeting, the distributions were also assayed in the absence of renal clearance (e.g., in mice rendered surgically anephric). In this model, the peak tumor retentions of the two higher affinity scFv approximated that reported previously for IgG targeting the same SK-OV-3 tumors in scid mice with intact kidneys. In contrast, the mutant with the lowest affinity for HER2/neu failed to accumulate in tumor, indicating the presence of an affinity threshold that must be exceeded for active in vivo tumor uptake. These results indicate that affinity can significantly impact the in vivo tumor-specific retention of scFv molecules.

Adenocarcinoma↗

PubMed1998

Phase IB trial for malignant melanoma using R24 monoclonal antibody, interleukin-2/alpha-interferon.

The inflammatory tumor lymphocytic infiltrates and spontaneous tumor regressions seen in patients with metastatic malignant melanomas suggest a cellular immune involvement. Enhancement of such responses has been the goal of R24 (GD3 ganglioside-specific) monoclonal antibody trials, alone and in combination with other agents. This study reports the results of 21 patients treated in a phase IB trial employing R24 (0, 5, 25, 50 mg/m2) administered by continuous i.v. infusion on days 1-5 followed by 3 MU each of interleukin-2 (IL-2) and alpha interferon (alpha-IFN) given subcutaneously on days 8-12, 15-19 and 22-26. R24-related toxicities occurred pre-dominantly at the 25 and 50 mg/m2 doses. One patient (50 mg/m2 R24) exhibited a dose-limiting Grade 4 anaphylaxis. Cytokine-related toxicities required IL-2/alpha-IFN dose reduction in two patients and early termination of treatment in five additional patients. Nine of 20 baseline biopsies showed chronic inflammation; six with lymphocytic tumor infiltration and three where inflammation was confined to the perivascular/peritumoral spaces. No day 8 or 29 biopsies in the R24-treated groups demonstrated treatment-induced tumor lymphocytic infiltrates. However, one patient randomized to no R24 treatment, showed a significant inflammatory tumor lymphocytic infiltration at days 8 and 29. Eighteen of 21 treated patients were evaluable for response. One (5%) patient receiving IL-2/alpha-IFN alone had stable disease lasting 1.5 years. Five (28%) R24, IL-2/alpha-IFN-treated patients had stable disease ranging from 6 to 32 weeks, with one patient remaining alive 2.5 years post-treatment. Although this combined treatment program was generally well tolerated, no objective responses were seen and significant R24-induced tumor lymphocytic infiltrates were not demonstrated.

Adult↗

PubMed1998

Characterization of anti-mouse Fc gamma RII single-chain Fv fragments derived from human phage display libraries.

BACKGROUND: Few antibodies are available to study the function of the Fc gamma RII murine immunoglobulin receptor. Human phage display libraries represent a potential source of single-chain Fv (sFv) to facilitate the study of the Fc gamma RII murine immunoglobulin receptor. OBJECTIVES: To isolate human sFv specific for mouse Fc gamma RII. STUDY DESIGN: Two human phage display libraries were selected for reactivity to mouse Fc gamma RII. Those human anti-mouse Fc gamma RII sFv that were derived from the libraries were characterized with respect to kinetics, cellular binding, epitope specificity and amino acid sequence. RESULTS: Nine anti-mouse Fc gamma RII sFv molecules were isolated from two human phage display libraries (Marks et al., J Mol Biol 1991;222:581-597; Sheets et al., Proc Natl Acad Sci USA, in press). Surface plasmon resonance (SPR) analysis revealed that the human anti-mouse Fc gamma RII sFv had off-rates ranging from 10(-2) to 10(-3) s-1, with KD values calculated to range between 10(-7) and 10(-9) M. The binding of the FITC-labeled human anti-mouse Fc gamma RII sFv to mouse peritoneal neutrophils was not detected by flow cytometry, due to the rapid off-rates of these monomeric proteins. However, when the human anti-mouse Fc gamma RII sFv were coated on yellow-green latex particles, all of the human sFv were found to specifically bind to mouse peritoneal neutrophils. Deglycosylation of mouse Fc gamma RII did not diminish the binding of these sFv, suggesting that the sFv molecules recognize a polypeptide epitope on murine Fc gamma RII. In contrast, denaturation of mouse Fc gamma RII dramatically reduced the binding of the human sFv, suggesting that the epitopes are conformational. Sequence analysis of the human anti-mouse Fc gamma RII sFv revealed a high degree of structural similarity among the nine sFv. The DP73 VH gene segment was utilized by four of the nine sFv, while seven of the nine sFv contained the DPL16 V lambda gene segment. The sequence similarities between these sFv suggested that several of the human sFv may recognize a common epitope on mouse Fc gamma RII. Epitope mapping studies demonstrated that eight of the nine human anti-mouse Fc gamma RII sFv recognized overlapping epitopes. All of these human anti-mouse Fc gamma RII sFv competed with the 2.4G2 rat monoclonal anti-mouse Fc gamma RII/III antibody for binding with mouse Fc gamma RII, suggesting that the targeted epitopes reside in or near the Fc binding pocket of mouse Fc gamma RII. CONCLUSIONS: The availability of novel sFv recognizing mouse Fc gamma RII will facilitate the study of receptor triggering events. Such sFv may prove useful to engage murine Fc gamma RII for targeted cytotoxicity or immunization strategies.

Amino Acid Sequence↗

PubMed1998

Prolonged in vivo tumour retention of a human diabody targeting the extracellular domain of human HER2/neu.

Single-chain Fv (scFv) molecules exhibit highly specific tumour-targeting properties in tumour-bearing mice. However, because of their smaller size and monovalent binding, the quantities of radiolabelled scFv retained in tumours limit their therapeutic applications. Diabodies are dimeric antibody-based molecules composed of two non-covalently associated scFv that bind to antigen in a divalent manner. In vitro, diabodies produced from the anti-HER2/neu (c-erbB-2) scFv C6.5 displayed approximately 40-fold greater affinity for HER2/neu by surface plasmon resonance biosensor measurements and significantly prolonged association with antigen on the surface of SK-OV-3 cells (t1/2 cell surface retention of > 5 h vs 5 min) compared with C6.5 scFv. In SK-OV-3 tumour-bearing scid mice, radioiodinated C6.5 diabody displayed a highly favourable balance of quantitative tumour retention and specificity. By as early as 4 h after i.v. administration, significantly more diabody was retained in tumour (10 %ID g(-1)) than in blood (6.7 %ID ml(-1)) or normal tissue (liver, 2.8 %ID g(-1); lung, 7.1 %ID g(-1); kidney, 5.2 %ID g(-1)). Over the next 20 h, the quantity present in blood and most tissues dropped approximately tenfold, while the tumour retained 6.5 %ID g(-1) or about two-thirds of its 4-h value. In contrast, the 24-h tumour retention of radioiodinated C6.5 scFv monomer was only 1 %ID g(-1). When diabody retentions were examined over the course of a 72-h study and cumulative area under the curve (AUC) values were determined, the resulting tumor-organ AUC ratios were found to be superior to those previously reported for other monovalent or divalent scFv molecules. In conclusion, the diabody format provides the C6.5 molecule with a distinct in vitro and in vivo targeting advantage and has promise as a delivery vehicle for therapeutic agents.

Animals↗

PubMed1998

Superantigen-targeted therapy: phase I escalating repeat dose trial of the fusion protein PNU-214565 in patients with advanced gastrointestinal malignancies.

Antibody-directed, superantigen-induced cytotoxicity has been shown to have potent in vitro and in vivo antitumor effects in preclinical models. In the present study, PNU-214565, a recombinant fusion protein consisting of the Fab of the monoclonal antibody C242 and staphylococcal enterotoxin A (SEA), was used in an escalating repeat dose Phase I clinical trial in patients with advanced gastrointestinal malignancies. A prior single-dose Phase I clinical trial had demonstrated safety at doses of 1.5 ng/kg with toxicities of fever and hypotension that were not dose related. Twenty-seven patients (age range, 36-75 years; median, 62; 14 males and 13 females; 23 colorectal and 4 pancreatic) were treated in the present study with one cycle of four consecutive daily 3-h infusions of PNU-214565 at doses of 0.15 ng/kg (n = 3); 0.5 ng/kg (n = 3), 1.5 ng/kg (n = 4), 2.75 ng/kg (n = 12), and 3.5 ng/kg (n = 5). All patients had a good performance status [Eastern Cooperative Oncology Group: PS = 0 (n = 15), PS = 1 (n = 12)]. As in the single-dose trial, fever and hypotension were the most common toxicities. Dose-limiting toxicity (DLT), consisting of transient hypotension responsive to dopamine, was experienced by one patient treated at the 2.75 ng/kg dose level. One patient with pancreatic cancer metastatic to the liver experienced a partial response of hepatic metastases with stable pancreatic head abnormalities by computed tomography scan. Further dose escalation was suspended when two patients treated in a companion repeat dose Phase I study experienced DLT at the 4 ng/kg dose level. Multiparameter analyses on all patients treated in the two companion single-dose and two-repeated-dose Phase I trials revealed that the levels of patients' pretreatment anti-SEA antibodies protected against toxicity at a given drug dose. By jointly considering weight and the baseline anti-SEA concentration in a patient, it is possible to assign a PNU-214565 dose that will induce systemic cytokine release (a surrogate test to assess for the presence of uncomplexed drug and its ability to induce systemic cellular activation) without DLT. This pharmacodynamically based dosing scheme will be tested in future repeated-dose clinical trials and will define maximally tolerated doses of this powerful new immunotherapy approach.

Adult↗

PubMed1997

Cysteine reactivity in Thermoanaerobacter brockii alcohol dehydrogenase.

The free cysteine residues in the extremely thermophilic Thermoanaerobacter brockii alcohol dehydrogenase (TBADH) were characterized using selective chemical modification with the stable nitroxyl biradical bis(1-oxy-2,2,5,5-tetramethyl-3-imidazoline-4-yl)disulfide, via a thiol-disulfide exchange reaction and with 2[14C]iodoacetic acid, via S-alkylation. The respective reactions were monitored by electron paramagenetic resonance (EPR) and by the incorporation of the radioactive label. In native TBADH, the rapid modification of one cysteine residue per subunit by the biradical and the concomitant loss of catalytic activity was reversed by DTT. NADP protected the enzyme from both modification and inactivation by the biradical. RPLC fingerprint analysis of reduced and S-carboxymethylated lysyl peptides from the radioactive alkylated enzyme identified Cys 203 as the readily modified residue. A second cysteine residue was rapidly modified with both modification reagents when the catalytic zinc was removed from the enzyme by o-phenanthroline. This cysteine residue, which could serve as a putative ligand to the active-site zinc atom, was identified as Cys 37 in RPLC. The EPR data suggested a distance of < or 10 A between Cys 37 and Cys 203. Although Cys 283 and Cys 295 were buried within the protein core and were not accessible for chemical modification, the two residues were oxidized to cystine when TBADH was heated at 75 degrees C, forming a disulfide bridge that was not present in the native enzyme, without affecting either enzymatic activity or thermal stability. The status of these cysteine residues was verified by site directed mutagenesis.

Alcohol Dehydrogenase↗

PubMed1997

Induction of multiple anti-c-erbB-2 specificities accompanies a classical idiotypic cascade following 2B1 bispecific monoclonal antibody treatment.

The bispecific monoclonal antibody (bsmAb) 2B1, targeting the extracellular domain of c-erbB-2, the protein product of the HER-2/neu proto-ocogene, and Fc gamma RIII (CD16), expressed by human natural killer cells, neutrophils and differentiated monocytes, mediates the specific cytotoxic activity of these effector cells to tumor cells. A group of 24 patients with c-erbB-2-overexpressing tumors were treated with intravenously administered 2B1 in a phase I clinical trial and followed after treatment to evaluate the diversity and extent of the 2B1-induced humoral immune responses. As expected, 17 of 24 patients developed human anti-(murine Ig) antibodies (HAMA) to whole 2B1 IgG in a range from 100 ng/ml to more than 50000 ng/ml; 10 of these patients (42%) had strong (at least 1000 ng/ml) HAMA responses, some of which were still detectable at day 191. These responses were usually associated with similar reactivity to the F(ab')2 fragments of the parental antibodies 520C9 (anti-c-erbB-2) and 3G8 (anti-CD16). We sought evidence of an idiotypic cascade induction, indicating a prolonged specific treatment-induced effect on at least one selected target of 2B1. Using competition-based enzyme-linked immunosorbent assays, specific anti-idiotypic antibodies (Ab2) were detectable against 520C9 in 11 patients and against 3G8 in 13 patients. Peak anti-idiotypic antibodies generally occurred 3-5 weeks from treatment initiation, with a downward trend thereafter. There was a statistically significant correlation among the induction of significant HAMA responses, anti-idiotypic antibody production and the development of antibodies to c-erbB-2. The anti-c-erbB-2 responses, which were distinct from anti-anti-idiotypic (Ab3) antibodies, were detected in the post-treatment sera of 6/16 patients examined. No obvious correlation could be made between the development of humoral immune responses, the dose received, and the clinical response. Future investigation involving 2B1 therapy will concentrate on investigating an association of these humoral responses to any c-erbB-2-specific cellular responses. Manipulations of 2B1 therapy effects that augment immunity to c-erbB-2 could provide additional avenues for immunotherapy with this and other bispecific antibodies.

Adenocarcinoma↗

PubMed1997

Biological therapies for gastrointestinal cancers.

Several new agents with promising activity in gastrointestinal malignancies have been identified in the past several years. Despite these advances, most advanced gastrointestinal malignancies cannot be cured by currently available agents or approaches. Accordingly, efforts to develop new treatment strategies continue to have urgent priority. Much interesting work has been done in the past year. The continued evaluation of these new strategies will identify those with the potential to have clinical effects on patients with gastrointestinal cancers.

Clinical Trials as Topic↗

PubMed1997

Superantigen-based immunotherapy: a phase I trial of PNU-214565, a monoclonal antibody-staphylococcal enterotoxin A recombinant fusion protein, in advanced pancreatic and colorectal cancer.

PURPOSE: To establish the maximum-tolerated dose (MTD) and define the toxicities of a single-dose infusion of PNU-214565, a recombinant Escherichia coli-derived fusion protein of Staphylococcal enterotoxin A (SEA) and the Fab-fragment of the C242 monoclonal antibody in patients with advanced colorectal and pancreatic carcinomas. To investigate the capability of PNU-214565 to induce a superantigen (SAg) response resulting in cytokine production and tumor regression. PATIENTS AND METHODS: Twenty-one patients (age range, 39 to 76 years; median, 64; 12 men, nine women; 18 colorectal, three pancreatic cancers) were treated with a single 3-hour infusion of PNU-214565, with doses ranging from 0.01 to 1.5 ng/kg. All patients had prior chemotherapy and a good performance status Eastern Cooperative Oncology Group [ECOG] performance status [PS] = 0 [n = 10]; PS = 1 [n = 11]), 10 had prior radiation, and 18 had prior surgery. RESULTS: Fever and hypotension were the most common toxicities. Fever of any grade occurred in 16 of 21 patients (76%): four of 21 (19%) with grade 2 and two of 21 (9.5%) with grade 3. Hypotension of any grade occurred in 13 of 21 (62%): four of 21 with grade 2 and one of 21 (5%) with grade 3. Interleukin-2 (IL-2) and tumor necrosis factor alpha (TNF alpha) induction correlated with toxicity. In the two patients with grade 3 fever, peak IL-2 and TNF alpha levels were 2.9 IU/mL and 165 pg/mL, and 8.3 IU/mL and 245 pg/mL, respectively. Transient, > or = 50% decreases in circulating monocytes were observed in 17 of 21 patients as early as 0.5 hours (median time, 2 hours) from the start of infusion. Decreases (mean 33%) in circulating lymphocytes were observed in seven of 21 patients. All three patients with grade 3 toxicity were treated at the 0.5-ng/kg dose. The significance of baseline anti-SEA, human antimouse antibody (HAMA), CA242-soluble antigen levels, and T-cell receptor variable beta region (TCR V beta) subsets and histocompatibility leukocyte antigen-DR (HLA-DR) genotypes was assessed as possible predictors of toxicity. All toxicities were transient and easily managed. No grade 3 toxicity occurred at the higher dose levels. CONCLUSION: PNU-214565, a SAg-based tumor targeted therapy, is safe when given as a single 3-hour infusion at doses up to 1.5 ng/kg. The MTD for a single dose was not determined. The safety of a repeated dose schedule is currently under investigation, beginning with doses determined to be safe in this trial.

Adult↗