Toxic-shock syndrome associated with phage-group-I Staphylococci

Seven children (aged 8--17 years) presented with a high fever, headache, confusion, conjunctival hyperaemia, a scarlatiniform rash, subcutaneous oedema, vomiting, watery diarrhoea, oliguria, and a propensity to acute renal failure, hepatic abnormalities, disseminated intravascular coagulation, and severe prolonged shock. One patient died, one had gangrene of the toes, and all have had fine desquamation of affected skin and peeling of palms and soles during convalescence. Five patients were studied prospectively. Staphylococcus aureus related to phage-group I was isolated from mucosal (nasopharyngeal, vaginal, tracheal), or sequestered (empyema, abscess) sites, but not from blood. This organism produces an exotoxin which causes a positive Nikolsky sign in the newborn mouse and which is biochemically, pathologically, and immunologically distinct from phage-group-II stapphylococcal exfoliatin.

Efficacy of the anti-CD22 recombinant immunotoxin BL22 in chemotherapy-resistant hairy-cell leukemia

BACKGROUND

Hairy-cell leukemia that is resistant to treatment with purine analogues, including cladribine, has a poor prognosis. We tested the safety and efficacy of an immunotoxin directed against a surface antigen that is strongly expressed by leukemic hairy cells.

METHODS

RFB4(dsFv)-PE38 (BL22), a recombinant immunotoxin containing an anti-CD22 variable domain (Fv) fused to truncated pseudomonas exotoxin, was administered in a dose-escalation trial by intravenous infusion every other day for a total of three doses.

RESULTS

Of 16 patients who were resistant to cladribine, 11 had a complete remission and 2 had a partial remission with BL22. The three patients who did not have a response received low doses of BL22 or had preexisting toxin-neutralizing antibodies. Of the 11 patients in complete remission, 2 had minimal residual disease in the bone marrow or blood. During a median follow-up of 16 months (range, 10 to 23), 3 of the 11 patients who had a complete response relapsed and were retreated; all of these patients had a second complete remission. In 2 of the 16 patients, a serious but completely reversible hemolytic-uremic syndrome developed during the second cycle of treatment with BL22. Common toxic effects included transient hypoalbuminemia and elevated aminotransferase levels.

CONCLUSIONS

BL22 can induce complete remissions in patients with hairy-cell leukemia that is resistant to treatment with purine analogues.

Streptococcal toxic-shock syndrome: spectrum of disease, pathogenesis, and new concepts in treatment

Since the 1980s there has been a marked increase in the recognition and reporting of highly invasive group A streptococcal infections with or without necrotizing fasciitis associated with shock and organ failure. Such dramatic cases have been defined as streptococcal toxic-shock syndrome. Strains of group A streptococci isolated from patients with invasive disease have been predominantly M types 1 and 3 that produce pyrogenic exotoxin A or B or both. In this paper, the clinical and demographic features of streptococcal bacteremia, myositis, and necrotizing fasciitis are presented and compared to those of streptococcal toxic-shock syndrome. Current concepts in the pathogenesis of invasive streptococcal infection are also presented, with emphasis on the interaction between group A Streptococcus virulence factors and host defense mechanisms. Finally, new concepts in the treatment of streptococcal toxic-shock syndrome are discussed.

Phase I trial of anti-CD22 recombinant immunotoxin moxetumomab pasudotox (CAT-8015 or HA22) in patients with hairy cell leukemia

PURPOSE

To conduct a phase I dose-escalation trial assessing safety and response of recombinant immunotoxin moxetumomab pasudotox (CAT-8015, HA22) in chemotherapy-resistant hairy cell leukemia (HCL).

PATIENTS AND METHODS

Eligible patients had relapsed/refractory HCL after ≥ two prior therapies and required treatment because of abnormal blood counts. Patients received moxetumomab pasudotox 5 to 50 μg/kg every other day for three doses (QOD ×3), with up to 16 cycles repeating at ≥ 4-week intervals if patients did not experience disease progression or develop neutralizing antibodies.

RESULTS

Twenty-eight patients were enrolled, including three patients each at 5, 10, 20, and 30 μg/kg, four patients at 40 μg/kg, and 12 patients at 50 μg/kg QOD ×3 for one to 16 cycles each (median, four cycles). Dose-limiting toxicity was not observed. Two patients had transient laboratory abnormalities consistent with grade 2 hemolytic uremic syndrome with peak creatinine of 1.53 to 1.66 mg/dL and platelet nadir of 106,000 to 120,000/μL. Drug-related toxicities in 25% to 64% of the 28 patients included (in decreasing frequency) grade 1 to 2 hypoalbuminemia, aminotransferase elevations, edema, headache, hypotension, nausea, and fatigue. Of 26 patients evaluable for immunogenicity, 10 patients (38%) made antibodies neutralizing more than 75% of the cytotoxicity of 1,000 ng/mL of immunotoxin, but this immunogenicity was rare (5%) after cycle 1. The overall response rate was 86%, with responses observed at all dose levels, and 13 patients (46%) achieved complete remission (CR). Only 1 CR lasted less than 1 year, with the median disease-free survival time not yet reached at 26 months.

CONCLUSION

Moxetumomab pasudotox at doses up to 50 μg/kg QOD ×3 has activity in relapsed/refractory HCL and has a safety profile that supports further clinical development for treatment of this disease.

Direct Intracerebral Delivery of Cintredekin Besudotox (IL13-PE38QQR) in Recurrent Malignant Glioma: A Report by the Cintredekin Besudotox Intraparenchymal Study Group

Purpose

Glioblastoma multiforme (GBM) is a devastating brain tumor with a median survival of 6 months after recurrence. Cintredekin besudotox (CB) is a recombinant protein consisting of interleukin-13 (IL-13) and a truncated form of Pseudomonas exotoxin (PE38QQR). Convection-enhanced delivery (CED) is a locoregional-administration method leading to high-tissue concentrations with large volume of distributions. We assessed the use of intracerebral CED to deliver CB in patients with recurrent malignant glioma (MG).

Patients and Methods

Three phase I clinical studies evaluated intracerebral CED of CB along with tumor resection. The main objectives were to assess the tolerability of various concentrations and infusion durations; tissue distribution; and methods for optimizing delivery. All patients underwent tumor resection followed by a single intraparenchymal infusion (in addition to the intraparenchymal one following resection), with a portion of patients who had a preresection intratumoral infusion.

Results

A total of 51 patients with MG were treated including 46 patients with GBM. The maximum tolerated intraparenchymal concentration was 0.5 μg/mL and tumor necrosis was observed at this concentration. Infusion durations of up to 6 days were well tolerated. Postoperative catheter placement appears to be important for optimal drug distribution. CB- and procedure-related adverse events were primarily limited to the CNS. Overall median survival for GBM patients is 42.7 weeks and 55.6 weeks for patients with optimally positioned catheters with patient follow-up extending beyond 5 years.

Conclusion

CB appears to have a favorable risk-benefit profile. CED is a complex delivery method requiring catheter placement via a second procedure to achieve accurate catheter positioning, better drug distribution, and better outcome.

Treatment of advanced solid tumors with immunotoxin LMB-1: an antibody linked to Pseudomonas exotoxin

Immunotoxin LMB-1 is composed of monoclonal antibody B3 chemically linked to PE38, a genetically engineered form of Pseudomonas exotoxin. B3 recognizes a carbohydrate antigen (Le(Y)) present on many human solid tumors. LMB-1 has excellent antitumor activity in nude mice bearing Le(Y)-positive tumors. We conducted a phase I study of 38 patients with solid tumors who failed conventional therapy and whose tumors expressed the Le(Y) antigen. Objective antitumor activity was observed in 5 patients, 18 had stable disease, 15 progressed. A complete remission was observed in a patient with metastatic breast cancer to supraclavicular nodes. A greater than 75% tumor reduction and resolution of all clinical symptoms lasting for more than six months was observed in a colon cancer patient with extensive retroperitoneal and cervical metastasis. Three patients (two colon, one breast cancer) had minor responses. The maximum tolerated dose of LMB-1 is 75 microgram/kg given intravenously three times every other day. The major toxicity is vascular leak syndrome manifested by hypoalbuminemia, fluid retention, hypotension and, in one case, pulmonary edema. Although immunotoxins have been evaluated in clinical studies for more than two decades, this is the first report of antitumor activity in epithelial tumors.

Safety, tolerability, and tumor response of IL4-Pseudomonas exotoxin (NBI-3001) in patients with recurrent malignant glioma

PURPOSE

This was an open-label, dose-escalation trial of intratumoral administration of IL-4 Pseudomonas exotoxin (NBI-3001) in patients with recurrent malignant glioma.

PATIENTS AND METHODS

A total of 31 patients with histologically verified supratentorial grades 3 and 4 astrocytoma were studied. Of these, 25 patients were diagnosed with glioblastoma multiforme (GBM) while six were diagnosed with anaplastic astrocytoma. Patients were over 18 years of age and had Karnofsky performance scores > or = 60. Patients were assigned to one of four dose groups in a dose-escalation fashion: 6 microg/ml x 40 ml, 9 microg/ml x 40 ml, 15 microg/ml x 40 ml, or 9 microg/ml x 100 ml of NBI-3001 administered via convection-enhanced delivery intratumorally using stereotactically placed catheters. Patients were followed with serial MRI scans and clinical assessments every four weeks for the first 16 weeks and then every eight weeks until week 26.

RESULTS

No drug-related systemic toxicity, as evident by lack of hematological or serum chemical changes, was apparent in any patients; treatment-related adverse effects were limited to the central nervous system. No deaths were attributable to treatment. Drug-related grade 3 or 4 toxicity was seen in 39% of patients in all dose groups and 22% of patients at the maximum tolerated dose of 6 microg/ml x 40 ml. The overall median survival was 8.2 months with a median survival of 5.8 months for the GBM patients. Six-month survival was 52% and 48%, respectively. Gadolinium-enhanced magnetic resonance imaging of the brain showed areas of decreased signal intensity within the tumor consistent with tumor necrosis following treatment in many patients.

CONCLUSIONS

NBI-3001 appears to have an acceptable safety and toxicity profile when administered intratumorally in patients with recurrent malignant glioma.

A protease-resistant immunotoxin against CD22 with greatly increased activity against CLL and diminished animal toxicity

Immunotoxins based on Pseudomonas exotoxin A (PE) are promising anticancer agents that combine a variable fragment (Fv) from an antibody to a tumor-associated antigen with a 38-kDa fragment of PE (PE38). The intoxication pathway of PE immunotoxins involves receptor-mediated internalization and trafficking through endosomes/lysosomes, during which the immunotoxin undergoes important proteolytic processing steps but must otherwise remain intact for eventual transport to the cytosol. We have investigated the proteolytic susceptibility of PE38 immunotoxins to lysosomal proteases and found that cleavage clusters within a limited segment of PE38. We subsequently generated mutants containing deletions in this region using HA22, an anti-CD22 Fv-PE38 immunotoxin currently undergoing clinical trials for B-cell malignancies. One mutant, HA22-LR, lacks all identified cleavage sites, is resistant to lysosomal degradation, and retains excellent biologic activity. HA22-LR killed chronic lymphocytic leukemia cells more potently and uniformly than HA22, suggesting that lysosomal protease digestion may limit immunotoxin efficacy unless the susceptible domain is eliminated. Remarkably, mice tolerated doses of HA22-LR at least 10-fold higher than lethal doses of HA22, and these higher doses exhibited markedly enhanced antitumor activity. We conclude that HA22-LR advances the therapeutic efficacy of HA22 by using an approach that may be applicable to other PE-based immunotoxins.

Intracerebral infusate distribution by convection-enhanced delivery in humans with malignant gliomas: descriptive effects of target anatomy and catheter positioning

OBJECTIVE

Convection-enhanced delivery (CED) holds tremendous potential for drug delivery to the brain. However, little is known about the volume of distribution achieved within human brain tissue or how target anatomy and catheter positioning influence drug distribution. The primary objective of this study was to quantitatively describe the distribution of a high molecular weight agent by CED relative to target anatomy and catheter position in patients with malignant gliomas.

METHODS

Seven adult patients with recurrent malignant gliomas underwent intracerebral infusion of the tumor-targeted cytotoxin, cintredekin besudotox, concurrently with 123I-labeled human serum albumin. High-resolution single-photon emission computed tomographic images were obtained at 24 and 48 hours and were coregistered with magnetic resonance imaging scans. The distribution of 123I-labeled human serum albumin relative to target anatomy and catheter position was analyzed.

RESULTS

Intracerebral CED infusions were well-tolerated and some resulted in a broad distribution of 123I-labeled human serum albumin, but target anatomy and catheter positioning had a significant influence on infusate distribution even within non-contrast-enhancing areas of brain. Intratumoral infusions were anisotropic and resulted in limited coverage of the enhancing tumor area and adjacent peritumoral regions.

CONCLUSIONS

CED has the potential to deliver high molecular weight agents into tumor-infiltrated brain parenchyma with volumes of distribution that are clinically relevant. Target tissue anatomy and catheter position are critical parameters in optimizing drug delivery.

Clinical evaluation of intraperitoneal Pseudomonas exotoxin immunoconjugate OVB3-PE in patients with ovarian cancer

OVB3-PE is an immunotoxin composed of a murine monoclonal antibody reactive with human ovarian cancer and conjugated to Pseudomonas exotoxin (PE). Twenty-three patients with refractory ovarian cancer were treated intraperitoneally (IP) with escalating doses of OVB3-PE to study toxicity, pharmacokinetics, antiimmunotoxin antibody formation, and antitumor response. Dose-limiting CNS toxicity occurred after repeated doses at 5 and 10 micrograms/kg. Other non-dose-limiting toxicities included transient elevation of liver enzymes, fever, and gastrointestinal toxicity. Pharmacokinetics of IP and serum OVB3-PE were determined in 16 patients. Peak peritoneal fluid levels exceeded the in vitro median effective dose at all doses tested. At doses of 1 to 2 micrograms/kg, the immunotoxin concentration in the peritoneal fluid remained constant for up to 8 hours and dropped to negligible levels after 12 hours. At the 5 and 10 micrograms/kg doses, levels remained high for up to 24 hours (greater than 100 ng/mL) and then gradually decreased and became undetectable (less than 4 ng/mL) after 72 hours. Serum levels of OVB3-PE were also analyzed in 16 patients. At doses of 1 micrograms/kg and 2 micrograms/kg, serum levels were not detectable (less than 5 ng/mL). However, after doses of 5 or 10 micrograms/kg, peak serum level occurred at 24 hours after each dose and dropped to negligible levels by 72 hours. Sera from 12 patients were analyzed for anti-PE antibodies and antibodies to mouse immunoglobulin (HAMA). All patients developed antibodies against PE within 14 days of therapy. Domain II of PE appeared to be the most immunogenic portion of the PE molecule. HAMA was detected on day 14 of therapy in nine patients, on day 21 in two, and on day 28 in one patient. No clinical antitumor responses were observed. We conclude that IP OVB3-PE at dose levels of 5 micrograms/kg (x 3) and 10 micrograms/kg (x 2) is accompanied by dose-limiting toxic encephalopathy. Neurologic toxicity is likely to be due to crossreactivity of OVB3 to normal human brain tissue, which was not appreciated during preclinical screening.

Real-time, image-guided, convection-enhanced delivery of interleukin 13 bound to pseudomonas exotoxin

PURPOSE

To determine if the tumor-targeted cytotoxin interleukin 13 bound to Pseudomonas exotoxin (IL13-PE) could be delivered to the brainstem safely at therapeutic doses while monitoring its distribution in real-time using a surrogate magnetic resonance imaging tracer, we used convection-enhanced delivery to perfuse rat and primate brainstems with IL13-PE and gadolinium-bound albumin (Gd-albumin).

EXPERIMENTAL DESIGN

Thirty rats underwent convective brainstem perfusion of IL13-PE (0.25, 0.5, or 10 microg/mL) or vehicle. Twelve primates underwent convective brainstem perfusion of either IL13-PE (0.25, 0.5, or 10 microg/mL; n = 8), co-infusion of 125I-IL13-PE and Gd-albumin (n = 2), or co-infusion of IL13-PE (0.5 microg/mL) and Gd-albumin (n = 2). The animals were permitted to survive for up to 28 days before sacrifice and histologic assessment.

RESULTS

Rats showed no evidence of toxicity at all doses. Primates showed no toxicity at 0.25 or 0.5 microg/mL but showed clinical and histologic toxicity at 10 microg/mL. Quantitative autoradiography confirmed that Gd-albumin precisely tracked IL13-PE anatomic distribution and accurately showed the volume of distribution.

CONCLUSIONS

IL13-PE can be delivered safely and effectively to the primate brainstem at therapeutic concentrations and over clinically relevant volumes using convection-enhanced delivery. Moreover, the distribution of IL13-PE can be accurately tracked by co-infusion of Gd-albumin using real-time magnetic resonance imaging.

Phase 1 study of the anti-CD22 immunotoxin moxetumomab pasudotox for childhood acute lymphoblastic leukemia

Novel therapies are needed to overcome chemotherapy resistance for children with relapsed/refractory acute lymphoblastic leukemia (ALL). Moxetumomab pasudotox is a recombinant anti-CD22 immunotoxin. A multicenter phase 1 study was conducted to determine the maximum-tolerated cumulative dose (MTCD) and evaluate safety, activity, pharmacokinetics, and immunogenicity of moxetumomab pasudotox in children, adolescents, and young adults with ALL (N = 55). Moxetumomab pasudotox was administered as a 30-minute IV infusion at doses of 5 to 50 µg/kg every other day for 6 (cohorts A and B) or 10 (cohort C) doses in 21-day cycles. Cohorts B and C received dexamethasone prophylaxis against capillary leak syndrome (CLS). The most common treatment-related adverse events were reversible weight gain, hepatic transaminase elevation, and hypoalbuminemia. Dose-limiting CLS occurred in 2 of 4 patients receiving 30 µg/kg of moxetumomab pasudotox every other day for 6 doses. Incorporation of dexamethasone prevented further dose-limiting CLS. Six of 14 patients receiving 50 µg/kg of moxetumomab pasudotox for 10 doses developed hemolytic uremic syndrome (HUS), thrombotic microangiopathy (TMA), or HUS-like events, exceeding the MTCD. Treatment expansion at 40 µg/kg for 10 doses (n = 11) exceeded the MTCD because of 2 HUS/TMA/HUS-like events. Dose level 6B (ie, 50 µg/kg × 6 doses) was the MTCD, selected as the recommended phase 2 dose. Among 47 evaluable patients, an objective response rate of 32% was observed, including 11 (23%) composite complete responses, 5 of which were minimal residual disease negative by flow cytometry. Moxetumomab pasudotox showed a manageable safety profile and evidence of activity in relapsed or refractory childhood ALL. This trial was registered at www.clinicaltrials.gov as #NCT00659425.

Effect of dosage on immunogenicity of a Vi conjugate vaccine injected twice into 2- to 5-year-old Vietnamese children

In a double-blind, randomized, and placebo-controlled previous trial, the efficacy of Vi-rEPA for typhoid fever in 2- to 5-year-olds was 89.0% for 46 months. Vi-rEPA contained 25 microg of Vi and induced a greater-than-eightfold rise in immunoglobulin G (IgG) anti-Vi in all of the vaccinees tested. In this investigation, we conducted a dosage-immunogenicity study of 5, 12.5, and 25 microg of Vi-rEPA in this age group. Two doses of Vi-rEPA were injected 6 weeks apart. Blood samples were taken before and at 10 weeks (4 weeks after the second injection) and 1 year later. All postimmunization geometric mean (GM) levels were higher than the preimmune levels (P < 0.0001). At 10 weeks, the GM IgG anti-Vi level elicited by 25 microg (102 EU/ml) was higher than those elicited by 12.5 microg (74.7 EU/ml) and 5 microg (43 EU/ml) (P < 0.004): all of the children had > or = 3.52 EU/ml (estimated minimum protective level). One year later, the levels declined about sevenfold (13.3 and 11.3 versus 6.43 EU/ml, P < 0.0001) but remained significantly higher than the preimmune levels (P < 0.0001), and >96% of the children had a greater-than-eightfold rise. This study also confirmed the safety and consistent immunogenicity of the four lots of Vi-rEPA used in this and previous trials.

Phase I trial of convection-enhanced delivery of IL13-Pseudomonas toxin in children with diffuse intrinsic pontine glioma

OBJECTIVE In this clinical trial report, the authors analyze safety and infusion distribution of IL13-Pseudomonas exotoxin, an antitumor chimeric molecule, administered via intratumoral convection enhanced delivery (CED) in pediatric patients with diffuse intrinsic pontine glioma (DIPG). METHODS This was a Phase I single-institution, open-label, dose-escalation, safety and tolerability study of IL13-PE38QQR infused via single-catheter CED into 5 pediatric DIPG patients. IL13-PE38QQR was administered to regions of tumor selected by radiographic findings. Two escalating dose levels were evaluated: 0.125 µg/mL in cohort 1 and 0.25 µg/mL in cohort 2. Real-time MRI was performed during intratumoral infusions, and MRI and MR spectroscopy were performed before and after the infusions. Clinical evaluations, including parent-reported quality of life (QOL), were assessed at baseline and 4 weeks post-infusion. RESULTS Direct infusion of brainstem tumor with IL13-PE using the CED technique in patients with DIPG produced temporary arrest of disease progression in 2 of 5 patients, both of whom subsequently received a second infusion. All 5 patients showed signs of disease progression by 12 weeks after initial infusion. Two patients experienced transient cranial nerve deficits and lethargy after infusion, and these deficits resolved with corticosteroid treatment in both cases. No patient had radiographic evidence of acute or long-term treatment toxicity. Parent-reported QOL was consistent with medical outcomes. CONCLUSIONS Even though IL13-PE delivered by CED did not reach the entire MRI-defined tumor volume in any patient, short-term radiographic antitumor effects were observed in 2 of the 5 patients treated. The patients’ performance status did not improve. Drug delivery using multiple catheters may produce improved outcomes. Clinical trial registration no.: NCT00088061 (clinicaltrials.gov) ABBREVIATIONS CED = convection-enhanced delivery; DIPG = diffuse intrinsic pontine glioma; IL-13 = interleukin 13; IL13R = IL-13 receptor; IPI = Impact of Pediatric Illness; KPS = Karnofsky Performance Status; LPS = Lansky Performance Status; MRS = MR spectroscopy; NAA = n-acetyl aspartate; QOL = quality of life; Vd = volume of distribution; Vi = volume of infusion.

Safety and immunogenicity of Staphylococcus aureus type 5 capsular polysaccharide-Pseudomonas aeruginosa recombinant exoprotein A conjugate vaccine in patients on hemodialysis

Seventeen volunteers with ESRD on hemodialysis, negative for infection with HIV or hepatitis B and C and not receiving immunosuppressive therapy, were injected two times 6 wk apart with 25 micrograms of Staphylococcus aureus Type 5 capsular polysaccharide-Pseudomonas aeruginosa exoprotein A (rEPA) conjugate. Controls were healthy adults, 18 to 44 yr old, injected previously with the same vaccine. None of the patients had fever or significant elevations in their SGOT or SGPT attributable to the vaccine. Two vaccinees had transient induration > 1 cm in diameter at the injection site. The preimmunization geometric mean (GM) Type 5 antibody levels of the ESRD patients and controls were similar. Type 5 antibody levels of the three major immunoglobulin (lg) classes rose at 2 and 6 wk after immunization (P < 0.001 for lgG, P < 0.005 for lgM, and P = 0.0001 for lgA). Reimmunization at 6 wk did not elicit a booster response. At 6 months, the GM lgG level of the patients was approximately 50% of that of the healthy volunteers and 14 of 17 had a more than fourfold higher antibody level than the preimmune value. The GM lgM level, in contrast, declined to the preimmunization value. Vaccine-induced Type 5 antibodies had opsonophagocytic activity. There was a slight increase of lgG antibodies to the heterologous S. aureus Type 8 polysaccharide (P < 0.01) that was sustained at 6 months. The S. aureus Type 5-rEPA vaccine is safe and immunogenic in ESRD patients, and evaluation of its effectiveness against S. aureus bacteremia in this at-risk group is planned.

Reconsidering targeted toxins to eliminate HIV infection: you gotta have HAART

The success of highly active anti-retroviral therapy (HAART) has inspired new concepts for eliminating HIV from infected individuals. A major obstacle is the persistence of long-lived reservoirs of latently infected cells that might become activated at some time after cessation of therapy. We propose that, in the context of treatment strategies to deliberately activate and eliminate these reservoirs, hybrid toxins targeted to kill HIV-infected cells be reconsidered in combination with HAART. Such combinations might also prove valuable in protocols aimed at preventing mother-to-child transmission and establishment of infection immediately after exposure to HIV. We suggest experimental approaches in vitro and in animal models to test various issues related to safety and efficacy of this concept.

Local convection enhanced delivery of IL4-Pseudomonas exotoxin (NBI-3001) for treatment of patients with recurrent malignant glioma

PURPOSE

This was an open-label, dose-escalation trial of intratumoral administration of IL-4 Pseudomonas Exotoxin (NBI-3001) in patients with recurrent malignant glioma.

PATIENTS AND METHODS

A total of 31 patients with histologically verified supratentorial grade 3 and 4 astrocytoma were studied. Of these, twenty-five patients were diagnosed with glioblastoma multiforme (GBM) while six were diagnosed with anaplastic astrocytoma (AA). Patients were over 18 years of age and had Karnofsky performance scores > or = 60. Patients were assigned to one of four dose groups in a dose-escalation fashion: 6 microg/ml x 40 ml, 9 microg/ml x 40 ml, 15 microg/ml x 40 ml, or 9 microg/ml x 100 ml of NBI-3001 administered intratumorally via stereotactically placed catheters. Patients were followed with serial MRI scans and clinical assessments every four weeks for the first 16 weeks and then every eight weeks until week 26.

RESULTS

No drug-related systemic toxicity, as evident by lack of hematological or serum chemical changes, was apparent in any patients; treatment-related adverse effects were limited to the central nervous system. No deaths were attributable to treatment. Drug-related Grade 3 or 4 toxicity was seen in 39% of patients in all dose groups and 22% of patients at the maximum tolerated dose of 6 microg/ml x 40 ml. The overall median survival was 8.2 months with a median survival of 5.8 months for the GBM patients. Six-month survival was 52% and 48%, respectively. Gadolinium-enhanced magnetic resonance imaging of the brain showed areas of decreased signal intensity within the tumor consistent with tumor necrosis following treatment in many patients.

CONCLUSIONS

NBI-3001 appears to have an acceptable safety and toxicity profile when administered intratumorally in patients with recurrent malignant glioma.

Long Term Survival in a Patient with Recurrent Malignantc Glioma Treated with Intratumoral Infusion of an IL4-Targeted Toxin (NBI-3001)

Intratumoral infusion of a recombinant targeted toxin (NBI-3001) consisting of the receptor binding domain of human interleukin 4 (IL-4) and Pseudomonas aeruginosa exotoxin A is an investigational treatment for malignant brain tumors. This 27-year-old male patient presented with a recurrent malignant glioma WHO grade IV after surgery and adjuvant radiation and chemotherapy. The recurrence was treated with intratumoral infusion of NBI-3001 at a dose of 9 microg/ml in 66 ml of infusate. Treatment resulted in long-term survival for 3 years after toxin infusion with a durable tumor response. There were some permanent neurological side effects resulting from toxin infusion. The patient eventually died after a late local recurrence of the known brain tumor. Such clinical evolution of a malignant glioma after a single round of immunotoxin infusion is rather unusual. The late local recurrence may suggest that repeated courses rather than a single infusion of intratumoral toxin are possibly needed for successful long-term tumor control.

Use of recombinant soluble CD4 Pseudomonas exotoxin, a novel immunotoxin, for treatment of persons infected with human immunodeficiency virus

Single and multiple doses of sCD4-PE40, a soluble recombinant fusion toxin selectively toxic to gp120-expressing cells, were evaluated in persons infected with human immunodeficiency virus type 1 (HIV-1). Seventeen of 24 patients who completed a single-dose safety trial were given either 1, 5, 10, or 15 micrograms/kg of sCD4-PE40 by intravenous bolus once a month for 2 months, then weekly for 6 weeks. The weekly maximally tolerated dose was 10 micrograms/kg. The major toxicity was a transient dose-dependent elevation in hepatic aminotransferases peaking 48 h after infusion. Anti-Pseudomonas exotoxin antibody developed in 58% of recipients, and sera from 13 of 17 showed neutralizing activity against sCD4-PE40. No consistent changes in immunologic or virologic markers were observed. Weekly infusions of < or = 10 micrograms/kg of sCD4-PE40 are generally well tolerated, but additional studies correlating optimal dosing and frequency of administration with efficacy will be needed to define the role of this novel agent in the management of HIV-1-infected patients.

Failure of short-term CD4-PE40 infusions to reduce virus load in human immunodeficiency virus-infected persons

The safety, immunologic, and antiviral effects of a recombinant biologic product that combines the second and third domains of the CD4 molecule and Pseudomonas exotoxin A (PE40) were evaluated in 21 human immunodeficiency virus (HIV)-infected subjects in a phase III open-label dose-ranging study. Subjects with CD4+ lymphocyte counts of 100-500/mm3 received CD4-PE40 at 40, 80, or 160 micrograms/m2 by infusion three to seven times over 10 days. At the maximum tolerated dose (80 micrograms/m2), peak CD4-PE40 levels were 65-130 ng/mL with a serum half-life of 3.6 +/- 1.5 h. Toxicity, primarily increased hepatic transaminases, was dose-related and reversible. HIV DNA proviral levels in peripheral blood mononuclear cells and plasma HIV RNA remained stable during and after CD4-PE40 infusions. The relative resistance of clinical isolates of HIV, limits of the tolerated dose, and the immunogenicity and short half-life of the protein may explain the lack of in vivo antiviral effect of CD4-PE40.

Diffuse lamellar keratitis: evaluation of etiology, histopathologic findings, and clinical implications in an experimental animal model

PURPOSE

To induce diffuse lamellar keratitis (DLK) and investigate the potential causative agents in an animal model.

SETTING

Magill Research Center for Vision Correction, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

In 70 eyes of 35 Dutch Belted rabbits, a corneal flap was cut and the interface randomly exposed to 1 of 7 substances: Pseudomonas aeruginosa endotoxin, 1 of 2 Staphylococcus aureus exotoxins, meibomian gland secretion, povidone-iodine 10%, Palmolive Ultra soap, and Klenzyme soap. Slitlamp examinations were performed 1, 3, 5, and 7 days postoperatively. The DLK was staged from 1 to 4. On day 7, the rabbits were killed and the eyes enucleated and processed for histopathologic examination.

RESULTS

At the end of the study, 54 eyes (46 exposed, 8 control) were available for evaluation. The 8 eyes studied concurrently in the control group remained clear and did not show interface inflammation. Thirty-one of 46 eyes (67%) treated with the various test substances developed DLK. The highest DLK rates were found with the cleaning soap Palmolive Ultra (100%; P =.022) and P. aeruginosa lipopolysaccharide endotoxin (90%; P =.026).

CONCLUSIONS

Interface inflammation was consistently induced in the animal model. All 7 agents caused DLK in at least some eyes. The histopathologic evaluation showed the morphologic profile of the marked inflammatory cellular reaction that occurred in almost all the specimens.

Anti-HIV-1 immunotoxin 3B3(Fv)-PE38: enhanced potency against clinical isolates in human PBMCs and macrophages, and negligible hepatotoxicity in macaques

Highly active antiretroviral therapy (HAART) against human immunodeficiency virus type 1 (HIV-1) infection dramatically suppresses viral load, leading to marked reductions in HIV-1 associated morbidity and mortality. However, infected cell reservoirs and low-level replication persist in the face of suppressive HAART, leading invariably to viral rebound upon cessation of treatment. Toxins engineered to target the Env glycoprotein on the surface of productively infected cells represent a complementary strategy to deplete these reservoirs. We described previously highly selective killing of Env-expressing cell lines by CD4(178)-PE40 and 3B3(Fv)-PE38, recombinant derivatives of Pseudomonas aeruginosa exotoxin A containing distinct targeting moieties against gp120. In the present report, we compare the in vitro potency and breadth of these chimeric toxins against multiple clinical HIV-1 isolates, replicating in biologically relevant primary human target cell types. In PBMCs, 3B3(Fv)-PE38 blocked spreading infection by all isolates examined, with greater potency than CD4(178)-PE40. 3B3(Fv)-PE38 also potently inhibited spreading HIV-1 infection in primary macrophages. Control experiments demonstrated that in both target cell types, most of the 3B3(Fv)-PE38 activity was due to selective killing of infected cells, and not merely to neutralization by the antibody moiety of the chimeric toxin. High-dose treatment of rhesus macaques with 3B3(Fv)-PE38 did not induce liver toxicity, whereas equivalent dosage of CD4(178)-PE40 induced mild hepatotoxicity. These findings highlight the potential use of 3B3(Fv)-PE38 for depleting HIV-infected cell reservoirs persisting in the face of HAART.

Safety and immunogenicity of Escherichia coli O18 O-specific polysaccharide (O-PS)-toxin A and O-PS-cholera toxin conjugate vaccines in humans

O-specific polysaccharide (O-PS) isolated from serotype 18 Escherichia coli lipopolysaccharide (LPS) was covalently coupled to either Pseudomonas aeruginosa toxin A (TA) or or cholera toxin (CT). The conjugates were nontoxic and nonpyrogenic. The conjugates were well tolerated on parenteral administration to human volunteers, with only mild, transient local reactions reported. Immunization engendered an IgG antibody response to both the O-PS and carrier protein. Anti-LPS antibody promoted the uptake and killing of an E. coli O18 strain bearing the K1 capsule by human polymorphonuclear leukocytes, which was complement dependent. Antibody to carrier protein neutralized the activity of native TA or CT in cell culture assays. Passively transferred IgG isolated from the serum of immunized donors provided a significant (P less than .01) degree of protection against fatal experimental E. coli O18 sepsis in mice. This study illustrates the potential use of such conjugates as vaccines against E. coli extraintestinal infections.

Cintredekin besudotox in treatment of malignant glioma

BACKGROUND

Interleukin-13 (IL-13) receptors are overexpressed in glioblastoma multiforme (GBM). The presence of IL-13 binding sites in GBM and their absence in normal brain tissue validates IL-13 receptor as an important target in human GBM.

OBJECTIVE

This review discusses the bench-to-bedside experience with a recombinant cytotoxin composed of human IL-13 and a truncated form of Pseudomonas exotoxin A (PE38QQR), delivered via convection-enhanced delivery (CED), in GBM treatment.

METHODS

The authors review publications regarding the laboratory research and clinical development of IL-13-directed therapies and summarize the future of IL-13-targeted cytotoxin.

CONCLUSION

The IL-13 receptor remains an important potential target in GBM, and preliminary experience with the IL-13-PE38QQR cytotoxin (also called cintredekin besudotox) has helped to pave the way for study of CED as an important means of drug delivery to malignant gliomas. Ongoing analysis of recently completed clinical trials will determine the future of this agent and its potential therapeutic targets.

Severe osteoarticular infection associated with Panton-Valentine leukocidin-producing Staphylococcus aureus

We report here a case of osteoarticular infection associated with Panton-Valentine leukocidin-producing Staphylococcus aureus. The 3-year-old child presented osteoarthritis associated with toxic shock syndrome, which was complicated by thrombosis, pneumonia, and diaphysitis, despite appropriate antibiotic treatment. Osteitis associated with toxinogenic S. aureus is rarely described. This case highlights the need of early and aggressive surgical treatment, in addition to appropriate antimicrobial therapy.