Randomized, placebo-controlled trial of mipomersen in patients with severe hypercholesterolemia receiving maximally tolerated lipid-lowering therapy

OBJECTIVES

Mipomersen, an antisense oligonucleotide targeting apolipoprotein B synthesis, significantly reduces LDL-C and other atherogenic lipoproteins in familial hypercholesterolemia when added to ongoing maximally tolerated lipid-lowering therapy. Safety and efficacy of mipomersen in patients with severe hypercholesterolemia was evaluated.

METHODS AND RESULTS

Randomized, double-blind, placebo-controlled, multicenter trial. Patients (n  = 58) were ≥18 years with LDL-C ≥7.8 mmol/L or LDL-C ≥5.1 mmol/L plus CHD disease, on maximally tolerated lipid-lowering therapy that excluded apheresis. Weekly subcutaneous injections of mipomersen 200 mg (n  = 39) or placebo (n  = 19) were added to lipid-lowering therapy for 26 weeks.

MAIN OUTCOME

percent reduction in LDL-C from baseline to 2 weeks after the last dose of treatment. Mipomersen (n = 27) reduced LDL-C by 36%, from a baseline of 7.2 mmol/L, for a mean absolute reduction of 2.6 mmol/L. Conversely, mean LDL-C increased 13% in placebo (n = 18) from a baseline of 6.5 mmol/L (mipomersen vs placebo p<0.001). Mipomersen produced statistically significant (p<0.001) reductions in apolipoprotein B and lipoprotein(a), with no change in high-density lipoprotein cholesterol. Mild-to-moderate injection site reactions were the most frequently reported adverse events with mipomersen. Mild-to-moderate flu-like symptoms were reported more often with mipomersen. Alanine transaminase increase, aspartate transaminase increase, and hepatic steatosis occurred in 21%, 13% and 13% of mipomersen treated patients, respectively. Adverse events by category for the placebo and mipomersen groups respectively were: total adverse events, 16(84.2%), 39(100%); serious adverse events, 0(0%), 6(15.4%); discontinuations due to adverse events, 1(5.3%), 8(20.5%) and cardiac adverse events, 1(5.3%), 5(12.8%).

CONCLUSION

Mipomersen significantly reduced LDL-C, apolipoprotein B, total cholesterol and non-HDL-cholesterol, and lipoprotein(a). Mounting evidence suggests it may be a potential pharmacologic option for lowering LDL-C in patients with severe hypercholesterolemia not adequately controlled using existing therapies. Future studies will explore alternative dosing schedules aimed at minimizing side effects.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00794664.

Developmental defects and neuromuscular alterations due to mitofusin 2 gene (MFN2) silencing in zebrafish: a new model for Charcot-Marie-Tooth type 2A neuropathy

The development of new animal models is a crucial step in determining the pathological mechanism underlying neurodegenerative diseases and is essential for the development of effective therapies. We have investigated the zebrafish (Danio rerio) as a new model to study CMT2A, a peripheral neuropathy characterized by the selective loss of motor neurons, caused by mutations of mitofusin 2 gene. Using a knock-down approach, we provide evidence that during embryonic development, mitofusin 2 loss of function is responsible of several morphological defects and motility impairment. Immunohistochemical investigations, revealing the presence of severe alterations in both motor neurons and muscles fibres, indicated the central role played by MFN2 in axonal and neuromuscular development. Finally, we demonstrated the ability of human MFN2 to balance the downregulation of endogenous mfn2 in zebrafish, further supporting the conserved function of the MFN2 gene. These results highlight the essential role of mitofusin 2 in the motor axon development and demonstrate the potential of zebrafish as a suitable and complementary platform for dissecting pathogenetic mechanisms of MFN2 mutations in vivo.

[AIDS: ethics and scientific investigation on human beings]

The experimentation on human beings of one or several therapeutic molecules discovered in laboratory is necessary and important because it helps to find new treatments or new diagnostic methods. But, it presents serious ethical problems. In this article we are analysing the example of the HIV infection. We are succinctly describing the research methods in laboratory for therapeutic molecules, first the experimentation on animals and then on human being in clinical trials. We will then try to show, with several examples, how during these last 25 years of HIV infection, the research of new molecules has not always respected the ethical rules set out in Helsinki declaration, "Code de la santé publique" or "Guide de bonnes pratiques cliniques-ICH" etc. We are discussing here the way to avoid these irregularities.

Inhibition of TGF-β2 with AP 12009 in Recurrent Malignant Gliomas: From Preclinical to Phase I/II Studies

Transforming growth factor-beta2 (TGF-beta2) is known to suppress the immune response to cancer cells and plays a pivotal role in tumor progression by regulating key mechanisms including proliferation, metastasis, and angiogenesis. For targeted protein suppression the TGF-beta2-specific antisense oligodeoxynucleotide AP 12009 was developed. In vitro experiments have been performed to prove specificity and efficacy of the TGF-beta2 inhibitor AP 12009 employing patient-derived malignant glioma cells as well as peripheral blood mononuclear cells (PBMCs) from patients. Clinically, the antisense compound AP 12009 was assessed in three Phase I/II-studies for the treatment of patients with recurrent or refractory malignant (high-grade) glioma WHO grade III or IV. Although the study was not primarily designed as an efficacy evaluation, prolonged survival compared to literature data and response data were observed, which are very rarely seen in this tumor indication. Two patients experienced long-lasting complete tumor remissions. These results implicate targeted TGF-beta2-suppression using AP 12009 as a promising novel approach for malignant gliomas and other highly aggressive, TGF-beta-2-overexpressing tumors.

Comparing transfection efficiency and safety for antisense oligodeoxyribonucleotide between phospholipids-based microbubbles and liposomes

OBJECTIVE

To compare transfection efficiency and safety for antisense oligodeoxynucleotides (AS-ODNs) between two type of phospholipids-based vectors.

METHODS

An AS-ODNs sequence HA824 combined with luciferase reporter plasmid was used. Under low intensity ultrasound (US), a breast cancer cell line SK-BR-3 was exposed to different concentration of microbubbles and liposomes. Transfection efficiency was detected by fluorescence microscopy. Cell viability was verified by propidium iodide assay. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the inhibitory effect of HA824 on HER-2 expression at mRNA level. Atomic force microscopy (AFM) scanning techniques was employed to observe the change of membrane pore size.

RESULTS

AS-ODNs transfection efficiency showed an increasing tend with microbubble concentration, but not with liposome concentration. Maximum transfection efficiency with minimum cell viability was achieved under 2% microbubble concentration. Too strong sonoporation activity would enlarge membrane pores significantly and cause low cell viability.

CONCLUSION

US-mediated AS-ODNs transfection enhanced by phospholipids-based microbubbles represents an effective and safe avenue.

Antisense knockdown of the rat alpha7 nicotinic acetylcholine receptor produces spatial memory impairment

Selective and brain penetrating pharmacological antagonists for use in clarifying a role of alpha7 nicotinic acetylcholine receptors (nAChR) in behavioral paradigms are presently unavailable. Studies in alpha7 knock-out mice (KO) have not revealed convincing changes in behavioral phenotype, in particular measures of cognition that include contextual fear conditioning and spatial memory, which may be due to compensatory developmental changes. Therefore, an antisense oligonucleotide (aON) targeted toward the 3'- and 5'-UTR coding regions of the rat alpha7 nicotinic acetylcholine receptor was used. Following central injection of aON into the lateral ventricle of Long Evans rats for 6 days, treated rats exhibited a significant 42% and 25% decrease in alpha7 nAChR densities in hippocampus and cortex, respectively, as measured by [(3)H]-methyllycaconitine (MLA) binding. There was no change in alpha4beta2 densities measured by [(3)H]-cytisine binding. Acquisition of Morris Water Maze (MWM) performance, a measure of spatial memory, was impaired in aON-treated rats. In addition, a reduction in target platform crossings during a subsequent probe-trial was observed. These data demonstrate the ability of this aON to reduce hippocampal and cortical alpha7 nicotinic receptor densities associated with impaired MWM performance and support the specific involvement of the alpha7 nAChR in spatial learning and memory, a phenotype not affected in alpha7 KO mice.

A phase II dose ranging, double-blind, placebo-controlled study of alicaforsen enema in subjects with acute exacerbation of mild to moderate left-sided ulcerative colitis

BACKGROUND

Alicaforsen is an antisense oligonucleotide designed to inhibit expression of human intercellular adhesion molecule 1. Previous clinical studies have demonstrated activity of alicaforsen enema in ulcerative colitis and pouchitis.

AIM

To determine the minimally effective dosing regimen of alicaforsen enema in subjects with mild to moderate left-sided ulcerative colitis.

METHODS

Randomized, placebo-controlled, double-blind, two-dose ranging multicentre study. One hundred and twelve subjects were equally randomized to receive one of four alicaforsen enema regimens or placebo daily for 6 weeks. Primary end point was Disease Activity Index at week 6. Secondary end points included evaluation of clinical improvement, relapse rates and durability of response. Analysis of data were performed on the intent-to-treat population.

RESULTS

No significant difference was observed between treatment arms and placebo in the primary end point. A prolonged reduction in mean% Disease Activity Index relative to baseline was observed in the daily 240 mg alicaforsen enema treatment arm in comparison with placebo from week 18 (51% vs. 18%, P=0.04) to week 30 (50% vs. 11%, P=0.03).

CONCLUSIONS

Alicaforsen enema was safe and well tolerated at all doses studied. The durability of the response to alicaforsen enema treatment may suggests a disease-modifying effect.

Safety and efficacy of two dose formulations of alicaforsen enema compared with mesalazine enema for treatment of mild to moderate left-sided ulcerative colitis: a randomized, double-blind, active-controlled trial

BACKGROUND

Alicaforsen is an antisense oligonucleotide inhibitor of intercellular adhesion molecule 1 protein expression with activity in subjects with ulcerative colitis and pouchitis.

AIM

To compare the effects of alicaforsen enema to standard of care mesalazine (mesalamine) enema in subjects with mild to moderate active left-sided ulcerative colitis.

METHOD

A randomized, double-blind, active-controlled multicentre clinical trial. Subjects received a nightly enema of 120 mg alicaforsen (n=55), 240 mg alicaforsen (n=50), or 4 g mesalazine (n=54) for 6 weeks, followed by a 24-week monitoring period. The primary end point was Disease Activity Index at week 6. Clinical improvement, remission and relapse were secondary end points.

RESULTS

No significant difference was observed between treatment arms in the primary end point. However, the median duration of response to alicaforsen enema treatment was two- to threefold longer (128 and 146 days) in comparison with mesalazine (54 days). Complete mucosal healing occurred in 24% of the 240 mg alicaforsen group, when compared with 17% in the mesalazine.

CONCLUSIONS

Alicaforsen enema demonstrated an acute response and safety profile similar to mesalazine enema, but was differentiated by a more durable response. The extended length of remission suggests that alicaforsen enema treatment may have a disease modifying effect.

Technology evaluation: alicaforsen (Isis)

Isis is developing alicaforsen, an RNase H-dependent antisense inhibitor of intercellular adhesion molecule-1, for the potential treatment of ulcerative colitis. The therapy is currently undergoing phase II clinical trials.

Phase II study of ISIS 3521, an antisense oligodeoxynucleotide to protein kinase C alpha, in patients with previously treated low-grade non-Hodgkin's lymphoma

BACKGROUND

The purpose of this study was to assess the efficacy and safety of ISIS 3521, an antisense phosphorothioate oligonucleotide to protein kinase C alpha in patients with relapsed low-grade non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Twenty-six patients received ISIS 3521 (2 mg/kg/day) as a continuous infusion over 21 days of each 28-day cycle.

RESULTS

The median age of the patients was 53 years (range 37-77). Histological subtypes were low-grade follicular lymphoma (n = 22) and B-cell small lymphocytic lymphoma (n = 4). Twenty-one (81%) had stage III/IV disease. The median number of previous lines of chemotherapy was two (range one to six). A total of 87 cycles of ISIS 3521 were administered. Twenty-three patients were assessable for response. Three patients achieved a partial response. No complete responses were observed. Ten patients had stable disease. Grade 3-4 toxicity was as follows: neutropenia (3.8%) and thrombocytopenia (26.9%).

CONCLUSIONS

ISIS 3521 has demonstrated anti-tumour activity in patients with relapsed low-grade NHL. There may be a potential role for this agent in combination with conventional chemotherapy for advanced low-grade lymphoma, and further trials are warranted.

A phase II trial of ISIS 3521 in patients with metastatic colorectal cancer

This phase II study was designed to characterize the clinical activity of ISIS 3521 in patients with metastatic colorectal cancer (CRC). Sixteen patients with pretreated or refractory CRC were treated with ISIS 3521. Eleven patients were given a dose of 2.0 mg/kg per day, and 5 patients received 3.0 mg/kg per day given over 21 days followed by a 7-day rest period. Patients continued with study until evidence of disease progression or unacceptable toxicity was detected. Patients underwent baseline tumor biopsies followed by a second biopsy during the last week of the first 21-day infusion. All 16 patients underwent baseline tumor biopsies, and 12 of the 16 patients underwent on-study tumor biopsies. No evidence of tumor response was observed. One patient had stable disease after 2 cycles and remained on for 1 additional cycle only to demonstrate progression of disease at that time. No dose-limiting or other significant toxicities were observed at both dosages, which could not be explained by progression of disease. Fatigue was common in all patients treated but was not dose limiting, and there was no evidence of coagulopathy. Analysis of the tumor biopsies obtained from the 11 evaluable samples showed marked uptake of ISIS 3521 in the normal liver parenchyma. However, there was minimal uptake within the tumor cells. In addition, no evidence of any alteration in protein kinase C-a within the tumors or any downstream effects leading to apoptosis were observed. ISIS 3521 demonstrated no clinical activity or target modulation in refractory metastatic CRC.

A randomised, controlled, double blind, escalating dose study of alicaforsen enema in active ulcerative colitis

OBJECTIVE

To evaluate the safety and efficacy of an enema formulation of alicaforsen, an antisense inhibitor of intercellular adhesion molecule, after 1, 3, and 6 months.

METHODS

This was a randomised, placebo controlled, double blind, escalating dose multicentre study in 40 patients with mild to moderately active distal ulcerative colitis (disease activity index (DAI) 4-10). Patients were assigned to four dosing cohorts of 10 patients each (eight active, two placebo). Each patient received 60 ml of alicaforsen enema (0.1, 0.5, 2, or 4 mg/ml or placebo) once daily for 28 consecutive days. Safety and efficacy (DAI and clinical activity index) scores were evaluated up to six months after initiation of dosing.

RESULTS

At day 29, alicaforsen enema resulted in dose dependent improvement in DAI (overall p = 0.003). Alicaforsen 4 mg/ml improved DAI by 70% compared with the placebo response of 28% (p = 0.004). Alicaforsen 2 and 4 mg/ml improved DAI status by 72% and 68% compared with a placebo response of 11.5% at month 3 (p = 0.016 and 0.021, respectively). Specifically, DAI improved from 5.6 to 1.6 and from 6.3 to 2.5 in the 2 and 4 mg/ml groups compared with placebo (7.5 to 6.1). None of the patients in the 4 mg/ml group compared with 4/8 placebo patients required additional medical or surgical intervention over baseline during the six month period after starting the enema treatment. The safety profile was favourable.

CONCLUSIONS

Alicaforsen enema showed promising acute and long term benefit in patients with mild to moderate descending ulcerative colitis. Alicaforsen enemas had a favourable safety profile. These findings require verification in larger randomised controlled clinical trials.

Spatial learning in rats is impaired by microinfusions of protein kinase C-gamma antisense oligodeoxynucleotide within the nucleus accumbens

The nucleus accumbens (NAcc) has been shown to play a role in motor and spatial learning. Protein kinase C (PKC) has been implicated in the mechanisms of initiation and maintenance of long-term potentiation that is thought to be involved in the storage of long-term memory. In the present study, the importance of de novo synthesis of PKC-gamma within the NAcc in the acquisition and retention of spatial discrimination learning was assessed using an antisense knockdown approach. Separate groups of Long-Evans rats were exposed to acute microinfusions (6microg/microl) of PKC-gamma antisense oligodeoxynucleotide (AS-ODN), control oligodeoxynucleotide (C-ODN) or vehicle into the NAcc at 24 and 3h before each training session. Behavioral findings showed that the blockade of NAcc-PKC-gamma translation caused impairments in the early phase of learning and retention of spatial information. Biochemical experiments showed that PKC-gamma expression was reduced and Ca(2+)/phospholipid-dependent protein kinase C (PKC) activity was blocked significantly in the AS-ODN-treated rats in comparison with control rats. The present findings suggest that NAcc-PKC-gamma plays a role during the early acquisition of spatial learning. Also, retention test results suggest that NAcc-PKC-gamma may be working as an intermediate factor involved in the onset of molecular mechanisms necessary for spatial memory consolidation within the NAcc.

A Phase II trial of aprinocarsen, an antisense oligonucleotide inhibitor of protein kinase C alpha, administered as a 21-day infusion to patients with advanced ovarian carcinoma

BACKGROUND

It has been postulated that protein kinase C alpha (PKC-alpha) plays a pivotal role in signal transduction in tumor cancer cells. Aprinocarsen, a 20-base antisense oligonucleotide, has shown ability to inhibit PKC-alpha protein expression and inhibit tumor growth in human xenograft models. In a previous Phase I trial, the authors demonstrated the safety and some evidence of activity in ovarian carcinoma of aprinocarsen administered as a 21-day, continuous, intravenous infusion.

METHODS

In this Phase II trial, 36 patients with advanced ovarian carcinoma were treated with aprinocarsen at a dose of 2 mg/kg per day delivered as a 21-day, continuous, intravenous infusion. The primary objective was to determine the antitumor response, and the secondary objectives were to evaluate toxicity and to evaluate effects on quality of life (QOL).

RESULTS

Between September 1997 and December 1999, 36 patients (median age, 58 years) were enrolled in this trial. Patients were stratified into 2 groups: a platinum-sensitive group (n = 12 patients) and a platinum-resistant group (n = 24 patients). All 36 patients were evaluable for toxicity, and 27 patients were fully assessable for antitumor response after 2 cycles of therapy. All patients had received prior treatments. No objective responses were noted in the platinum-sensitive group. In the platinum-resistant group, 1 patient had some evidence of antitumor activity indicated by a decrease in serum CA 125 and stable disease on imaging studies for 8 months. No changes were noted in overall patient ratings for any of the five QOL domains.

CONCLUSIONS

When it was administered as a single agent, aprinocarsen did not have significant clinical activity in patients with advanced ovarian carcinoma. Further study may be warranted in combination with platinum-based regimens.

Technology evaluation: LErafAON, NeoPharm

NeoPharm is developing liposome-encapsulated, c-Raf antisense oligodeoxynucleotides (LErafAON) for the potential treatment of various solid tumors, including those that have become resistant to radiation or chemotherapy. Phase I/II trials commenced in March 2001 and were ongoing as of June 2003.

Phase II study of CGP 69846A (ISIS 5132) in recurrent epithelial ovarian cancer: an NCIC clinical trials group study (NCIC IND.116)

OBJECTIVE

ISIS 5132 is a 20-base phosphorothioate DNA oligonucleotide against human c-raf kinase, a downstream effector of ras oncogene function. C-raf kinase is a molecule in the MAP kinase signaling cascade which is essential for cellular proliferation, the overexpression of which leads to malignant expression. Activity of this compound was documented in a woman with ovarian cancer in a Phase I study.

METHODS

We evaluated ISIS 5132 at a dose of 4 mg/kg/day by continuous venous infusion, administered for 21 days q 4 weeks in 22 patients with recurrent ovarian cancer in a standard two-stage Phase II design. Three patients were ineligible; 19 patients are evaluable for toxicity and 16 for response. All patients had previously received systemic therapy for ovarian cancer (6 had one and 13 had two prior regimens). Patients were treated with a median of two cycles and 79% of the patients received >90% planned dose intensity.

RESULTS

ISIS 5132 was well tolerated with no episodes of Grade 3 or 4 hematologic or biochemical (creatinine, AST, bilirubin) toxicity. There were six episodes of grade 3 nonhematologic toxicity in 4 patients thought to be treatment related (lethargy 2; anorexia 1; abdominal pain 2; shortness of breath 1). No responses were seen in the 16 patients who are evaluable for response; 4 had stable disease for a median of 3.8 months and 12 patients had documented progressive disease.

CONCLUSION

ISIS 5132 at 4 mg/kg/day as a single agent did not show activity in recurrent ovarian cancer.

Targeting intracellular signal transduction. A new paradigm for a brave new world of molecularly targeted therapeutics

Significant advances in the field of molecular biology over the past decade have led to a new era in cancer therapeutics, with an explosion of rationally designed therapeutic strategies directed against selective molecular targets. The complex array of aberrant signal transduction proteins involved in carcinogenesis has been the focus of target-based anticancer agents. Inhibitors of intracellular signal transduction represent a unique approach in that they inhibit critical downstream regulatory proteins, which are vital to the process of cellular communication. Although these agents are in early-phase evaluations, the preliminary data suggest that they are well tolerated and capable of target inhibition in surrogate and tumor tissue. Although the primary therapeutic benefit of these agents is expected to be decreased tumor growth, evidence suggests that objective tumor responses may also be achieved. There are many unresolved questions pertaining to the development of this class of compounds, including selection of optimal dose and schedule, determination of relevant endpoints, methods for target validation, and strategies for combination with cytotoxic agents. However, despite the numerous unresolved issues, the emergence of this class of compounds has resulted in an undeniable impact on the present and future of cancer therapeutics.

Effect of intraperitoneal mRNA antisense-oligodeoxynucleotides to cholecystokinin on anxiety-like and learning behaviors in rats: association with pre-experimental stress

RATIONALE

Cholecystokinin and its analogs generate anxiety in humans and measurable anxiety-like behaviors in rats. Cholecystokinin receptor blockers have been reported to have variable effects in the treatment of anxiety disorders. We demonstrated that intracerebroventricular administration of Cholecystokinin-antisense oligodeoxynucleotides (ASODN) for 3 days significantly diminished anxiety-like behavior in rats.

OBJECTIVE

This study was designed to examine the effects of peripheral (intraperitoneal) administration of Cholecystokinin-ASODN on anxiety-like and learning behaviors in rats, in general and in a pre-experiment stress paradigm.

METHODS

In the first study Cholecystokinin-ASODN was injected intraperitoneally to rats five times at 24-h intervals. Control groups received injections of either a scrambled oligodeoxynucleotide (ScrODN) or vehicle. On the sixth day, the rats were assessed in the elevated plus-maze paradigm and in the Morris water maze. In the second study, rats were pre-exposed to a cat for 10 min as a model for psychological stress, and then treated with intraperitoneal Cholecystokinin-ASODN and tested in both paradigms.

RESULTS

The results show that for intact rats, intraperitoneal Cholecystokinin-ASODN significantly increased anxiety-like behavior and impaired retention performance in the Morris water maze, compared to both control groups. In stressed rats, Cholecystokinin-ASODN reduced anxiety-like behaviors in the plus-maze and improved performance in the water maze compared with controls.

CONCLUSIONS

These results indicate that the anxiolytic effect of intraperitoneal Cholecystokinin-ASODN may be dependent on the baseline endogenous level of stress (i.e., on the Cholecystokinin levels). Basal endogenous levels of Cholecystokinin, as well as exogenous dosage of Cholecystokinin agonists and/or anxiolytic agents, appear to play an important role in the expression and/or control of anxiety-related behaviors in rats.

Phase II randomized study of ISIS 3521 and ISIS 5132 in patients with locally advanced or metastatic colorectal cancer: a National Cancer Institute of Canada clinical trials group study

BACKGROUND

Because treatment of metastatic colon cancer is noncurative, new treatments are needed. This trial evaluated the antitumor effects of two targeted anticancer agents: (a) ISIS 3521, an antisense inhibitor of the protein kinase C alpha; and (b) ISIS 5132, an antisense inhibitor of c-raf kinase in patients untreated previously with recurrent or metastatic colorectal carcinoma.

PATIENTS AND METHODS

All patients had colorectal adenocarcinoma with measurable disease and no prior chemotherapy for metastatic disease. Patients were randomized to receive either ISIS 3521 or ISIS 5132 at a dose of 2 mg/kg/day as a continuous i.v. infusion 21 of 28 days. Cycles were repeated as long as progression was not seen, and doses of both agents were modified according to toxic effects. A two-arm study design was used with each study arm considered independently. Steady-state blood levels of both antisense molecules were measured on days 8, 15, and 22 of the first cycle of therapy.

RESULTS

Thirty-seven eligible patients were enrolled, and 32 were evaluable for response (17 receiving ISIS 3521 and 15 receiving ISIS 5132). No responses were noted. Four of the patients receiving ISIS 3521 had stable disease, and 5 patients receiving ISIS 5132 were stable.

CONCLUSION

Neither ISIS 5132 nor ISIS 3521given in the dose and schedule studied induced objective responses in untreated colorectal cancer patients.

CpG motifs in bacterial DNA and their immune effects

Unmethylated CpG motifs are prevalent in bacterial but not vertebrate genomic DNAs. Oligodeoxynucleotides (ODN) containing CpG motifs activate host defense mechanisms leading to innate and acquired immune responses. The recognition of CpG motifs requires Toll-like receptor (TLR) 9, which triggers alterations in cellular redox balance and the induction of cell signaling pathways including the mitogen activated protein kinases (MAPKs) and NF kappa B. Cells that express TLR-9, which include plasmacytoid dendritic cells (PDCs) and B cells, produce Th1-like proinflammatory cytokines, interferons, and chemokines. Certain CpG motifs (CpG-A) are especially potent at activating NK cells and inducing IFN-alpha production by PDCs, while other motifs (CpG-B) are especially potent B cell activators. CpG-induced activation of innate immunity protects against lethal challenge with a wide variety of pathogens, and has therapeutic activity in murine models of cancer and allergy. CpG ODN also enhance the development of acquired immune responses for prophylactic and therapeutic vaccination.

A randomized, placebo controlled trial of an antisense oligodeoxynucleotide to intercellular adhesion molecule-1 in the treatment of severe rheumatoid arthritis

OBJECTIVE

To determine the safety of an antisense oligodeoxynucleotide to intercellular adhesion molecule-1 (ICAM-1) (ISIS 2302), administered in an intensive 4 week regimen with dose escalation; and to provide preliminary evidence for efficacy in rheumatoid arthritis (RA).

METHODS

Patients with active RA were enrolled in a 6 month, double blind, placebo controlled, dual center, dose escalation (0.5, 1, and 2 mg/kg) study. Subjects received a total of 13 intravenous ISIS 2302 infusions, given on alternate days for 2 weeks and then 3 times a week for another 2 weeks. Doses of corticosteroids (< or = 10 mg/day) and disease modifying antirheumatic drugs (stable > or = 3 months) remained constant throughout the study. The primary efficacy endpoint was the Day 26 Paulus index, with secondary evaluations at Months 2-6.

RESULTS

A total of 43 patients were enrolled with 11, 10, 3, and 19 patients receiving placebo or 0.5, 1, or 2 mg/kg of ISIS 2302, respectively. There were no differences between groups after randomization and the mean baseline swollen joint count was 22.5. Pharmacokinetic studies revealed a T(1/2) of 63 min and first-order kinetics with slight dose dependency, suggesting a saturable clearance process, although no accumulation was noted with repeat dosing. The Paulus 20% responses at Day 26 were 20%, 0%, and 5% for patients treated with ISIS 2302 (0.5, 1, 2 mg/kg, respectively) and 36% with placebo. For Months 2-6, the average intent-to-treat Paulus 20% responses were 21.2% for ISIS 2302 and 12.6% for placebo. Only ISIS 2302 treated subjects (19%) achieved Paulus 50% responses. ISIS 2302 was well tolerated. An expected and transient mean activated partial thromboplastin time increase of roughly 7 s was observed at the highest dose (2 mg/kg), as were small and clinically insignificant increases in serum C3a levels. T/B cell immunophenotyping, recall antigen skin testing, and serum immunoglobulin levels revealed no significant immunosuppressive effects.

CONCLUSION

This study shows that 13 ISIS 2302 infusions over 4 weeks are well tolerated in patients with active RA. Although significant efficacy was not evident at the primary endpoint (1 month), the study lacked sufficient power to draw any formal conclusions. We tested a 4-fold drug concentration range, which led to a lower area under the curve range than was therapeutic in a subsequent Crohn's disease trial. Any further evaluation of this well tolerated ICAM-1 antisense agent should therefore be conducted at higher dosing.

Phase II trial with ISIS 5132 in patients with small-cell (SCLC) and non-small cell (NSCLC) lung cancer. A European Organization for Research and Treatment of Cancer (EORTC) Early Clinical Studies Group report

Two multicentre phase II trials were designed to determine if tumour responses can be achieved in progressive small-cell lung cancer (SCLC) or non-small cell lung cancer (NSCLC) patients treated with ISIS 5132, an inhibitor of C-raf kinase mRNA expression (CGP 69846A; ISIS Pharmaceuticals Inc, Carlsbad, CA), and to further characterise the safety of the compound. Between August 1998 and November 1999, 26 patients (18 NSCLC, 8 SCLC) were entered. Out of these, 23 were eligible, 22 (18 NSCLC, 4 SCLC) were treated with ISIS 5132 (2 mg/kg/day, 21 days continuous intravenous (i.v.) infusion every 4 weeks) and were evaluable for toxicity and 18 (15 NSCLC, 3 SCLC) were evaluable for efficacy. For the whole group haematological toxicity did not exceed grade 2. One patient experienced a grade 4 increased prothrombin time. Non-haematological toxicity was mild to moderate, with the observation of asthenia and nausea and vomiting. Progressive disease (PD) was diagnosed in 10 patients (8 NSCLC and 2 SCLC). 8 more patients (7 NSCLC, 1 SCLC) were considered as treatment failures. In conclusion, this study using ISIS 5132 with this dose and schedule of administration excludes a 20% response rate with 95% confidence intervals for NSCLC and cannot draw any conclusions for SCLC patients as only a few were involved in the study.

ISIS-3521. Isis Pharmaceuticals

ISIS-3521 is a 20-mer antisense phosphorothioate oligonucleotide PKCa expression inhibitor, under development by Isis (formerly in collaboration with Novartis) for the potential treatment of solid tumors that are refractory to, or recurrent with, standard treatment regimens [175741]. In November 1999, Novartis announced that it would end its codevelopment of ISIS-3521 [348221], [348222]. In August 2001, Eli Lilly in-licensed ISIS-3521 [420062]. In October 2000, phase III trials of ISIS-3521, in combination with carboplatin and paclitaxel, were initiated for the treatment of non-small cell lung cancer (NSCLC) [386128]. The FDA granted ISIS-3521 Fast Track review status for NSCLC in November 2000 [388930]. In April 2001, Bear Sterns & Co predicted US approval of ISIS-3521 in 2002 [411081]. In August 2001, Eli Lilly and Isis entered into a four-year strategic alliance that includes ISIS-3521. For the license of ISIS-3521, Isis will receive $25 million in upfront fees and will be reimbursed for remaining phase III development and registration costs [420062].

Alicaforsen. Isis Pharmaceuticals

Alicaforsen (ISIS-2302) is an RNase H-dependent antisense inhibitor of the intercellular adhesion molecule ICAM-1 under development by Isis Pharmaceuticals, for the potential treatment of a variety of inflammatory disorders [175741]. As of April 1997 it was in phase III trials for Crohn's disease (CD); however, the trial failed and, in December 1999, the company suspended development for this indication [352801]. In October 2000, the company re-initiated development in CD [384820] and new phase III trials had begin by May 2001 [409704]. In August 2000, phase II studies of alicaforsen in an enema formulation for ulcerative colitis and a topical formulation for psoriasis were ongoing [378715]. Development of the compound for the potential treatment of rheumatoid arthritis (RA) was discontinued in 1999 [347579]. By the end of 1998, alicaforsen was in phase II trials for kidney transplant rejection. At this time, these trials were expected to finish in mid-1999 [343460]. However, they were ongoing in September 1999, although no further development has been reported for this indication since that time [338672]. In February 1995, Isis Pharmaceuticals and Boehringer Ingelheim (BI) signed a collaborative agreement on cell adhesion inhibitors, including alicaforsen [174111]. By early 1999, Isis and BI were to decide on the next developmental step for alicaforsen following further analyses of its performance against CD [292915], [315439]. Their joint development agreement was terminated in 1999; Isis regained rights to the product and by September 1999 was in talks to license alicaforsen to another partner for CD [338672]. In June 2000, Cytogenix entered into a sponsored research agreement with Baylor College of Medicine at the Texas Medical Center Houston for the use of its ssDNA expression system for the development of antisense strategies directed against intercellular adhesion molecules for the purpose of reducing lung inflammation and injury in disease states and conditions [369677]. US-05514788, and other patents, cover antisense cell adhesion molecule inhibitors [212289], [234792].

Absence of efficacy of subcutaneous antisense ICAM-1 treatment of chronic active Crohn's disease

BACKGROUND & AIMS

ISIS-2302, an antisense oligonucleotide directed against intercellular adhesion molecule 1, was effective in steroid refractory Crohn's disease in a pilot trial. The aim of this study was to investigate safety and efficacy of ISIS-2302 in chronic active Crohn's disease (CACD).

METHODS

A dose-interval, multicenter, placebo-controlled trial was conducted in 75 patients with steroid-refractory CACD (Crohn's Disease Activity Index [CDAI], 200-400). The primary endpoint was steroid-free remission (CDAI <150) at week 14.

RESULTS

Only 2 of 60 (3.3%) ISIS-2302-treated and no placebo patients reached the primary endpoint. Steroid-free remission at week 26 (secondary endpoint) was reached in 8 of 60 (13.3%) active treatment and 1 of 15 (6.7%) placebo patients. A greater proportion of ISIS-2302-treated than placebo patients achieved a steroid dose <10 mg/day at weeks 14 and 26 (48.3% vs. 33.3% and 55.0% vs. 40.0%, respectively, and a glucocorticoid dose of 0 mg [prednisone equivalent] at week 26 [23.3% vs. 6.7%, respectively]). Treatment with ISIS-2302 was safe. The most common side effects were injection site reactions in the active treatment group (23% in ISIS-2302-treated patients vs. none in placebo patients). No statistically significant differences in the frequency of side effects were detected between dose groups.

CONCLUSIONS

The trial did not prove clinical efficacy of ISIS-2302 based on the primary endpoint. Positive trends were observed in some of the secondary endpoints.

Phase I Trial of ISIS 5132, an antisense oligonucleotide inhibitor of c-raf-1, administered by 24-hour weekly infusion to patients with advanced cancer

Raf-1 is a serine/threonine kinase that functions as a critical effector of Ras-mediated signal transduction via the mitogen-activated protein kinase pathway. Constitutive activation of this pathway directly contributes to malignant transformation in many human tumors. A 20-base phosphorothioate oligonucleotide complementary to c-raf-1 mRNA (ISIS 5132; CGP 69846A) has been shown to specifically suppress Raf-1 expression both in vitro and in vivo. This Phase I trial, involving 22 patients with advanced cancer, was designed to evaluate the safety, feasibility, and maximum tolerated dose of ISIS 5132 administration as a weekly 24-h i.v. infusion. Pharmacokinetic analysis was performed, and c-raf-1 mRNA levels in peripheral blood mononuclear cells were assessed using quantitative reverse transcription-PCR. This trial defined a maximum tolerated dose of 24 mg/kg/week on this schedule. Two of four patients treated at 30 mg/kg/week had serious adverse events after the first dose of ISIS 5132, including acute hemolytic anemia and acute renal failure and anasarca. There were no major responses documented. Dose-dependent complement activation was demonstrated on this schedule, but not on previously evaluated schedules, of ISIS 5132 administration. In contrast to other trials of ISIS 5132, there appeared to be no consistent suppression of peripheral blood mononuclear cell c-raf-1 mRNA level on this schedule at any of the dose levels analyzed. These data suggest that the efficacy and toxicity profiles of antisense oligonucleotides may be highly dependent on the schedule of administration and support the analysis of the putative molecular target in the evaluation of novel therapeutics.

[Antisense targeting in neurology]

INTRODUCTION

Antisense targeting refers to the use of synthetic short lengths of single stranded DNA, or RNA with base sequences complementary to a specific gene or its mRNA. Commonly, synthetic oligonucleotides are designed to hybridize to specific mRNA and thus preventing its translation in a specific protein.

DEVELOPMENT

The use of this technology as research tool is well known since two decades ago, but it has been in the last few years, when it has been proposed as a promising tool for the development of a new generation of drugs with high specificity, relative ease of production and low rate of toxicity. Antisense therapeutics is currently being evaluated in clinical trials for cancer, inflammation, and viral diseases. In the field of Neuropharmacology, it has become in a very valuable tool to block the expression of specific genes in vitro as well in the living brain. In this article, we review the contributions of this technology in the field of the Neurosciences, and also give an overview concerning the advances of the antisense strategy in the design of possible new treatments for certain neurological disorders. Other clinically relevant information regarding molecular biology, pharmacokinetics, mechanism of action, and side effects of antisense oligonucleotides has been collected and summarized.

CONCLUSIONS

In the neuropharmacological area is the Neurooncology the most intensively researched; nevertheless, the lack of oligos that cross the blood-brain barrier in sufficient amount continues being one of the main difficulties for the successful application of this technique on the central nervous system.

A phase I trial of c-Raf kinase antisense oligonucleotide ISIS 5132 administered as a continuous intravenous infusion in patients with advanced cancer

Raf proteins play a central role in the mitogen-activated protein kinase signaling pathway and hence are involved in oncogenic transformation and tumor cell proliferation. ISIS 5132 is a 20-base antisense phosphorothioate oligodeoxyribonucleotide that specifically down-regulates c-raf expression. We report here an initial study of the safety and tolerability of an i.v. infusion of ISIS 5132 in patients with advanced cancer. A continuous i.v. infusion of ISIS 5132 was administered for 21 days every 4 weeks to 34 patients with a variety of solid tumors refractory to standard therapy. The dose of ISIS 5132 was increased in sequential cohorts of patients, as toxicity allowed, until a final dose of 5.0 mg/kg body weight was reached. Toxicity was scored by common toxicity criteria, and tumor response was monitored. Pharmacokinetic studies were performed for 30 patients treated at doses of < or =4.0 mg/kg/day. The initial dose of ISIS 5132 was 0.5 mg/kg body weight and was successfully increased incrementally to 5.0 mg/kg body weight. Toxicities through the 4.0 mg/kg dose level were not dose limiting. Side effects were minimal and could not be specifically related to ISIS 5132. Two patients had prolonged stabilization of their disease, and one patient with ovarian carcinoma had a significant response with a 97% reduction in CA-125 levels. ISIS 5132, an antisense oligonucleotide against c-raf, was well tolerated at doses up to and including 4.0 mg/kg/day by 21-day continuous i.v. infusion and demonstrated antitumor activity at the doses tested.

c-raf-1 depletion and tumor responses in patients treated with the c-raf-1 antisense oligodeoxynucleotide ISIS 5132 (CGP 69846A)

Abnormally regulated signaling through proliferative signal transduction pathways characterizes many of the common solid tumors. The best described of these involves potentially oncogenic proteins of the Ras family, which activate Raf proteins in the early steps of the mitogen-activated protein kinase cascade. ISIS 5132, a phosphorothioate antisense oligodexoynucleotide directed to the 3' untranslated region of the c-raf-1 mRNA, inhibits the growth of human tumor cell lines in vitro and in vivo in association with specific down-regulation of target message expression. Using a semiquantitative reverse transcription-PCR assay, we analyzed changes in c-raf-1 mRNA expression in peripheral blood mononuclear cells collected from patients with advanced cancers treated with ISIS 5132 as part of a clinical trial. Specimens were collected for analysis pretreatment and on days 3, 5, 8, and 15 of the first cycle and on day 1 of each subsequent cycle. We observed significant reductions of c-raf-1 expression from baseline by day 3 in 13 of 14 patients (P = 0.002). The time course and depletion of c-raf-1 message in peripheral blood mononuclear cells paralleled the clinical benefit in two patients. These findings demonstrate that ISIS 5132 specifically reduces target gene expression in treated patients and that peripheral blood mononuclear cells are suitable tissues for biomarker studies in future trials.

Phase I study of an antisense oligonucleotide to protein kinase C-alpha (ISIS 3521/CGP 64128A) in patients with cancer

Protein kinase C (PKC) is an attractive target in cancer therapy. It is overexpressed in a variety of cancers, and nonspecific inhibitors of PKC have demonstrated antitumor activity. Antisense oligonucleotides targeted against PKC-alpha, which have high specificity, can inhibit mRNA and protein expression as well as the growth of tumors in vitro and in vivo. This Phase I study sought to characterize the safety profile and to determine the maximum tolerated dose of antisense to PKC-alpha when administered by continuous infusion in patients. Patients with incurable malignancies received ISIS 3521, a 20-length phosphorothioate oligodeoxynucleotide specific for PKC-alpha. Treatment was delivered over a period of 21 days by continuous i.v. infusion followed by a 7-day rest period. Doses were increased from 0.5 to 3.0 mg/kg/day. Patients continued on the study until evidence of disease progression or unacceptable toxicity was detected. Between August 1996 and September 1997, 21 patients were treated in five patient cohorts. The maximum tolerated dose was 2.0 mg/kg/day. The dose-limiting toxicities were thrombocytopenia and fatigue at a dose of 3.0 mg/kg/day. Pharmacokinetic measurements showed rapid plasma clearance and dose-dependent steady-state concentrations of ISIS 3521. Evidence of tumor response lasting up to 11 months was observed in three of four patients with ovarian cancer. The recommended dose of ISIS 3521 for Phase II studies is 2.0 mg/kg/day when given over a period of 21 days. Side effects are modest and consist of thrombocytopenia and fatigue. Evidence of antitumor activity provides the rationale for Phase II studies in ovarian cancer and other malignancies.

Phase I evaluation of ISIS 3521, an antisense oligodeoxynucleotide to protein kinase C-alpha, in patients with advanced cancer

PURPOSE

To determine the maximum-tolerated dose (MTD) and pharmacologic behavior of ISIS 3521 (ISI 641A), an antisense phosphorothioate oligonucleotide to protein kinase C-alpha.

PATIENTS AND METHODS

Thirty-six patients with advanced cancer received 99 cycles of ISIS 3521 (0.15 to 6.0 mg/kg/d) as a 2-hour intravenous infusion administered three times per week for 3 consecutive weeks and repeated every 4 weeks. Plasma and urine sampling was performed during the first week of treatment and subjected to capillary gel electrophoresis to determine full-length antisense oligonucleotide in addition to chain-shortened metabolites.

RESULTS

Drug-related toxicities included mild to moderate nausea, vomiting, fever, chills, and fatigue. Hematologic toxicity was limited to thrombocytopenia (grade 1, four patients; grade 2, one patient; grade 3, one patient). There was no relationship between dose, maximum concentration of the drug (C(max)), or area under the plasma concentration versus time curve (AUC) and coagulation times or complement levels. Dose escalation was discontinued because of the attainment of peak plasma concentrations, which approached that associated with complement activation in primates. Two patients with non-Hodgkin's lymphoma who completed 17 and nine cycles of therapy achieved complete responses. The pharmacokinetic profile of ISIS 3521 revealed a short elimination half-life (18 to 92 minutes), as well as a dose-dependent decrease in clearance and dose-dependent increases in C(max), AUC, and elimination half-life.

CONCLUSION

No dose-limiting toxicity of ISIS 3521 was identified, and clinical activity was observed. A short elimination half-life was identified, which suggests that alternate schedules with prolonged administration may be necessary for further clinical development.

Technology evaluation: GEM-92, Hybridon Inc

Hybridon is developing GEM-92, a second generation, orally administered antisense oligonucleotide directed against the gag gene in HIV-1 mRNA, as a potential treatment for HIV-1 infection and AIDS 11973841. It is a follow-up compound to GEM-91, which was discontinued due to dose-limiting toxicities [256660]. GEM-92 is undergoing phase I trials in the UK, in approximately 13 healthy volunteers. Hybridon intends to administer a single oral dose at one of three dose levels, while a fourth group will receive a single intravenous dose, in order to determine differences between oral and intravenous administration [263095]. GEM-92 has demonstrated significant inhibition of HIV-1 replication in various cell culture systems, and increased stability in comparison with GEM-91 [219621]. Hybridon has been issued two US patents; US-05652355 and US-05652356, claiming chemically advanced mixed backbone oligonucleotides [257135].

Phase I clinical/pharmacokinetic and pharmacodynamic trial of the c-raf-1 antisense oligonucleotide ISIS 5132 (CGP 69846A)

PURPOSE

Raf-1 is a protein kinase that plays a broad role in oncogenic signaling and acts as a downstream effector of Ras in the mitogen-activated protein kinase pathway. The present study was designed to determine the maximum-tolerated dose (MTD), toxicity profile, pharmacokinetics, and antitumor activity of the c-raf-1 antisense oligodeoxynucleotide ISIS 5132 (CGP 69846A; ISIS Pharmaceuticals Inc, Carlsbad, CA). The effect of ISIS 5132 on c-raf-1 gene expression in peripheral-blood mononuclear cells (PBMCs) of treated patients was studied using a reverse transcriptase polymerase chain reaction assay.

PATIENTS AND METHODS

Patients with refractory malignancies received ISIS 5132 as a 2-hour intravenous infusion three times weekly for 3 consecutive weeks. Pharmacokinetic sampling was performed during the first cycle in all patients; PBMCs for c-raf-1 mRNA analysis were collected at baseline and on days 3, 5, 8, and 15 of cycle 1 and on day 1 of each cycle thereafter.

RESULTS

Thirty-one patients received ISIS 5132 at one of nine dose levels ranging from 0.5 mg/kg to 6.0 mg/kg. Clinical toxicities included fever and fatigue, but these were not dose limiting. A clinically defined MTD was not reached. The harmonic mean half-life of ISIS 5132 was 59.8 minutes (range, 35.5 to 107.3 minutes). The area under the concentration-time curve increased linearly with dose, and mean plasma clearance was 1.86 mL/kg/min (range, 1.21 to 2.41 mL/kg/min). Two patients experienced prolonged stable disease lasting more than 7 months, which was associated with persistent reduction in c-raf-1 expression in PBMCs. Significant decreases in c-raf-1 expression were identified at time points after the baseline value (P <.05) at doses >/= 2.5 mg/kg.

CONCLUSION

ISIS 5132 is well tolerated at doses up to 6.0 mg/kg when administered as a thrice weekly 2-hour infusion for 3 consecutive weeks. The pharmacokinetic behavior of the drug is reproducible, and suppression of target gene expression is observed in circulating PBMCs.

Technology evaluation: ISIS-3521

It is well known that the PKC family of enzymes is involved in the propagation of intracellular signals and is implicated in cancers, inflammatory processes, cardiovascular and endocrinological diseases. Relatively low isozyme specificity has largely limited the clinical use of PKC antagonists. The members of the PKC family differ from each other at the mRNA level and the selectivity of antisense compounds is distinguished by this feature. According to ISIS Pharmaceuticals Inc antisense compounds are highly selective inhibitors even within a family of closely-related genes [321211]. The use of these compounds could be invaluable as tools to discover the mechanisms and roles of specific PKC isozyme in normal and diseased tissues and could provide the information for better cancer treatments [226799]. The isozyme of PKC-alpha is believed to play an important role in the proliferation of several types of cancer cells [234471-323703]. Recently, ISIS Pharmaceuticals received a patent US-05885970, covering the antisense technique targeting human PKC-alpha for cancer therapy (US-0588970). In the past few years, several effective antisense oligonucleotides (AS ONs) targeting murine and human PKC-alpha isozymes have been developed and a series of positive results have been obtained in cell culture and in nude mice cancer transplantation [327453]. Phase I clinical trials have shown that relatively high doses were well tolerated with no obvious side-effects [226799]. Whether these AS ONs are beneficial to patients suffering from cancer, either alone or in combination with other chemotherapy drugs is still under evaluation in a clinical setting.

Toward antisense oligonucleotide therapy for cancer: ISIS compounds in clinical development

Antisense oligonucleotides offer the promise of therapeutic effect with few toxic effects, by virtue of their high selectivity. Preclinical studies have provided evidence of antisense effects in vitro and in vivo, and phase I clinical trials have demonstrated safety, feasibility and activity of antisense oligonucleotides for the treatment of cancer. This review summarizes the status of development of three anticancer antisense oligonucleotides from ISIS Pharmaceuticals.

Brain as a unique antisense environment

During the last few years, antisense oligodeoxyribonucleotides (asODN) have become a commonly used tool for blocking of gene expression in the mammalian central nervous system. Successful gene inhibition has been reported for such diverse targets as those encoding neurotransmitter receptors, neuropeptides, trophic factors, transcription factors, cytokines, transporters, ion channels, and others. This review presents a discussion of recent studies on ODN in the brain, with a focus on specific approaches taken by the researchers in this field and especially on peculiar features of this organ as a milieu for asODN action. It is concluded that from the presented literature survey no coherent view on how to rationally design ODN for brain studies has emerged.

Pharmacokinetics and tolerability of intravenous trecovirsen (GEM 91), an antisense phosphorothioate oligonucleotide, in HIV-positive subjects

Trecovirsen, a 25-mer antisense phosphorothioate oligonucleotide targeted at the gag site of the HIV gene, was administered to HIV-positive volunteers as an i.v. infusion. Single doses ranged from 0.1 to 2.5 mg/kg in an ascending escalation in cohorts of 6 to 12 subjects. Plasma trecovirsen concentrations and pharmacokinetic parameters could be assessed at doses > or = 0.3 mg/kg. Peak plasma concentrations and AUC values increased disproportionately with increasing dose while elimination half-life increased and plasma clearance decreased, indicating a saturable process over this dose range. The only significant adverse event observed was an isolated, transitory increase in activated partial thromboplastin time at doses > or = 2.0 mg/kg that was related to plasma trecovirsen concentrations and is attributed to the polyanionic character of the molecule. Thus, trecovirsen administration was well tolerated in single i.v. doses up to 2.5 mg/kg.