RESEARCH - Phase I trial shows transfer of IL1-Ra gene into RA joints is safe, feasible

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Phase I trial shows transfer of IL1-Ra gene into RA joints is safe, feasible

Rheumawire

June 20, 2005

Janis

Pittsburgh, PA - Gene transfer of complementary DNA (cDNA) that codes for

the interleukin-1 receptor antagonist (IL-1Ra) can be safely done into the

joints of patients with rheumatoid arthritis (RA), can cause expression of

IL-1Ra in the synovial tissues of those joints, and should be developed

further for the treatment of arthritis and related disorders, according to

Dr H (University of Pittsburgh, PA) and colleagues. The

investigators report the first trial of intra-articular RA gene therapy

online June 14, 2005 in the Proceedings of the National Academy of Sciences

[1].

" The most important aspect of the study is that it establishes proof of

principle that gene transfer can be done safely to human joints. This is

important because there's resistance to using gene therapy for nonlethal

indications, " (who is now at Harvard Medical School, Boston) tells

rheumawire.

Gene transfer: A replacement for treatment with monoclonal antibodies?

Gene therapy is seen as a potentially less expensive, more durable

alternative to currently available biologics. The IL-1Ra blocker anakinra

(Kineret, Amgen) is approved for use in RA and under study in other diseases

but has a short half-life, requires daily injections (and may not maintain

therapeutic serum levels between injections), and, like most of the

biologics, costs in the neighborhood of $1000 per month.

" Intra-articular delivery by gene transfer promises to confer a therapeutic

advantage because of its ability to generate a high, sustained, local

concentration of IL-1Ra that, unlike its recombinant counterpart, has

undergone authentic posttranslational processing, " said.

The primary objective of this phase 1 study was to determine whether gene

transfer to human joints could be done safely. The investigators cautiously

waited for five years post-gene transfer to report these safety data, which

were the result of a phase 1 clinical trial conducted at the University of

Pittsburgh School of Medicine between 1996 and 1999.

The trial included nine women with severe RA who were already scheduled for

replacement of the second to fifth metacarpophalangeal (MCP) joints on one

hand and for additional surgical procedures on at least one other joint. The

researchers maximized safety by delivering the therapeutic gene to joints

already scheduled for total joint replacement.

The gene-therapy agent was constructed by transferring human IL-1Ra cDNA to

autologous synovial fibroblasts obtained at the time of elective surgery on

joints other than the target MCP joints. The synoviocytes were expanded in

culture, and half were transfected with a retrovirus carrying the human

IL-1Ra DNA. The rest were used as untransduced controls. All cultures were

checked to be sure they were free of replication-competent retrovirus,

endotoxin, mycoplasma, and other adventitious agents before they were used

in the study.

For each subject, two MCP joints were injected with transduced cells and two

with untransduced cells in a double-blind procedure. Doses were 1x106,

1.5-5x106, or 6.5-10x106 cells per joint.

Patients were monitored daily by telephone for adverse events. The main

adverse effect was transient discomfort during the intra-articular

injections. " No adverse events were reported during daily telephone contact.

Participants are now more than five years post-gene transfer, and they

remain free from replication-competent retrovirus and adverse events related

to the study, " the investigators write.

On day 7 after gene transfer, all of the injected MCP joints underwent the

scheduled replacement with Silastic implants and the retrieved synovial

tissues were examined for IL-1Ra expression by reverse

transcription-polymerase chain reaction (RT-PCR) and enzyme-linked

immunosorbent assay (ELISA). In situ hybridization and immunohistochemistry

were used to determine where the transduced cells were located.

Researchers removed synovium from joints in the patient's hand during

already-scheduled elective surgery (1). The synovial fibroblasts were

cultured (2), and half were transfected with the retroviral vector bearing

the IL1-Ra gene (3). All cells were tested to rule out contamination with

adventitious agents and replication-competent retrovirus (4). Two MCP joints

were injected with the fibroblasts encoding IL1-Ra, and two other MCP joints

were injected with control fibroblasts (5). All injected joints were removed

during joint-replacement surgery (6) and were examined for IL1-Ra gene

expression (7). [Click on the image to see a larger view.] Copyright 1999

University of Pittsburgh Medical Center. Used with permission.

reports that IL-1Ra messenger RNA (mRNA) derived from the transgene

was found in all of the treated joints but in only one control joint, a

fifth MCP. Cultures of cells from patients who received the lowest dose of

modified cells showed little IL-1Ra synthesis, but in 11 of 12 joints

receiving the higher doses, IL-Ra production was significantly elevated

(p=0.01).

Both and coauthor Dr D Robbins (University of Pittsburgh School

of Medicine) tell rheumawire that although the phase 1 trial showed that

ex-vivo gene transfer is possible for treating RA, the procedure is too

unwieldy for practical use.

" These data demonstrate that it is possible to transfer genes to human

joints and to achieve intra-articular transgene expression in a safe and

acceptable manner, but I was surprised how tedious, expensive, and generally

inefficient this type of ex vivo gene delivery is. That's why the emphasis

now is on in vivo approaches. We have been working on the problems of

maintaining long-term gene expression and transitioning from ex vivo to in

vivo gene delivery (and trying to get funded), " says.

One hot prospect for in vivo gene transfer is adeno-associated virus (AAV),

which has been studied in cystic fibrosis and several other diseases.

tells rheumawire that he has just been awarded a US National

Institutes of Health grant for a clinical trial in osteoarthritis using AAV

IL-1Ra. also notes that Targeted Genetics Inc (Seattle, WA) has a

phase 1 trial of an AAV-TNF:Fc receptor blocker under way in RA.

Related data on that construct were reported June 3, 2005 at the 8th annual

meeting of the American Society of Gene Therapy (St Louis, MO) by Dr

V Giannobile, who found that AAV could be used to deliver the recombinant

receptor Fc fusion protein (TNFR:Fc) transgene to periodontal lesions in

mice and that such treatment blocks progression of periodontitis [2]. Also

at that meeting, researchers, led by Dr AZ Zhao (ACTC Gene Technology LTD,

Beijing, China), reported that intra-articular gene transfer of a rat

TNFR:Fc construct suppressed collagen-induced arthritis [3]. Both of these

approaches mimic treatment with etanercept (Enbrel, Amgen, Wyeth), as

's approach mimics treatment with anakinra.

Robbins said, " I believe that we still have to develop the appropriate in

vivo gene-delivery approach. Although an ex vivo approach is clearly

feasible, the expense and the problems of handling cells make this approach

not feasible for treating millions of arthritis patients. If we can develop

a safe method for delivery of genes to joints by direct injection of the

vector, I think gene therapy for arthritis could become commonplace. "

Sources

1. CH, Robbins PD, Ghivizzani SC, et al. Gene transfer

to human joints: Progress toward a gene therapy of arthritis. Proc Nat Acad

Sci 2005; DOI: 10.1073/pnas.0502854102 ; available at

www.pnas.org/cgi/doi/10.1073/pnas.0502854102.

2. Taba M, Huffer HH, Shelburne CE, et al. Gene delivery of

TNFR:Fc by adeno-associated virus vector blocks progression of

periodontitis. American Society of Gene Therapy 8th annual meeting; June 3,

2005; St Louis, MO. Abstract 677.

3. Zhao AZ, Gao K, Dong XY, et al. Intraarticular gene

transfer of rat TNFR:Fc suppressed CIA arthritis. American Society of Gene

Therapy 8th annual meeting; June 3, 2005; St Louis, MO. Abstract 127.

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Mayo Clinic in Rochester

http://www.mayoclinic.org/rochester

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