CENTER OF EXCELLENCE IN IMMUNOLOGY

STEERING COMMITTEE MEETING

SUMMARY MINUTES

June 18, 2007

# CENTER OF EXCELLENCE IN IMMUNOLOGY

**STEERING COMMITTEE MEETING**

June 18, 2007\
1:00--3:00 p.m.

**Bldg. 10, Room 2S35**

**Videoconference to Frederick, Bldg. 549, Executive Room**

> **Members present:** Dr. Robert Wiltrout *(Chair)*
>
> Dr. Jay Berzofsky
>
> Dr. Stephen Creekmore *(Adjunct)*
>
> Dr. Diana Linnekin
>
> Dr. Joost Oppenheim
>
> Dr. Marjorie Robert-Guroff
>
> Dr. Steven Rosenberg
>
> Dr. Jeffrey Schlom
>
> Dr. Giorgio Trinchieri
>
> Dr. Thomas Waldmann
>
> **Members absent:** Dr. Jonathan Ashwell
>
> Dr. Allan Hildesheim
>
> Dr. Ronald Gress
>
> Dr. Jeffrey Lifson
>
> Dr. Douglas Lowy
>
> Dr. Crystal Mackall
>
> Ms. Karen Maurey *(Adjunct)*
>
> Dr. Ira Pastan
>
> Dr. Dale Shoemaker
>
> Dr. Alfred Singer
>
> Dr. Dinah Singer
>
> Dr. Robert Yarchoan
>
> Dr. Howard Young
>
> **Guests:** Ms. Donna Bialozor
>
> Mr. Ray Butler
>
> Dr. Petra Delgado
>
> Dr. Barbara Felber
>
> Dr. Laura Hooper
>
> Dr. Lauren Wood

######### Handouts

1.  Agenda

2.  Program of the CEI-sponsored conference *Cancer and Inflammation*

3.  Update on the Trans-NIH Initiative in Autoimmunity, Immunity, and
    Inflammation

overview

The Center of Excellence in Immunology Steering Committee (CEI SC)
convened its monthly meeting on June 18, 2007, at 1:00 p.m. Dr. Robert
Wiltrout provided a brief update on interleukin (IL)-12 availability
issues and IL-15 manufacturing. Dr. George Pavlakis gave a presentation
on the development of IL-15 plasmids for clinical use. Dr. Giorgio
Trinchieri presented the final program for the CEI-sponsored conference
*Cancer and Inflammation* and provided an update on the preparation of
the Trans-NIH Initiative in Immunity, Autoimmunity, and Inflammation.

new/old business

Dr. Wiltrout explained that there will be sufficient human IL-12
(hIL-12) material for clinical and research studies. A clinical lot of
hIL-12 is being reevaluated by the Cancer Therapy Evaluation Program
(CTEP) and will be available shortly. Wyeth Pharmaceuticals has agreed
to provide NCI with a batch of R&D-grade hIL-12 for laboratory studies;
the material needs to be revialed before it can be released.

Dr. Wiltrout continued that the National Institute of Arthritis and
Infectious Diseases (NIAID) is concerned about the delays in IL-15
protein production in the *E.coli* expression system by the
Biopharmaceutical Development Program (BDP). It is possible that NIAID
will seek alternative approaches to increase the possibility of success
by engaging an outside contractor to produce IL-15 in mammalian cells.
However, the feasibility of IL-15 production in mammalian cells is
unknown at the moment. Center for Cancer Research (CCR) and BDP staff
will meet to review progress in IL-15 production in *E. coli.* The CEI
SC cautioned that IL-15 produced in *E. coli* is likely to be
immunogenic as it will lack the complex glycosylation pattern
characteristic of IL-15.

update on the IL-15 project

Dr. Pavlakis provided an update on his project to develop plasmids
encoding IL-15 and its receptor IL‑15Rα for clinical use. He reiterated
that according to his data the best clinical candidate would be a
combination of IL-15 and IL‑15Rα, as the dimer is more stable and active
than IL-15 alone. Dr. Pavlakis, in collaboration with Dr. Barbara
Felber, has shown that IL-15 and IL‑15Rα are produced in the same cell,
associate in intracellular vesicles, and are transported to the cell
surface, where IL‑15Rα is rapidly cleaved and generates soluble IL‑15Rα
(sIL‑15Rα). Dr. Pavlakis postulates that the "real" cytokine is not
IL-15 alone but the cell-associated dimer IL-15/IL‑15Rα  and the
secreted dimer IL‑15/sIL‑15Rα, which bind to the IL‑15Rβγ receptor in
the target cells. Dr. Waldmann mentioned animal data suggesting that
although IL‑15Rα expression is required for IL-15 activity, it may not
be absolutely necessary that both proteins be expressed by the same cell
(*J Exp Med*. 2003;197:977-84).

Dr. Pavlakis explained that he has optimized the vectors for producing
IL-15 and IL‑15Rα; coordinated expression of both proteins is required
for maximum production and stability. He has conducted *in vivo*
experiments with the optimized vectors for IL‑15/IL‑15Rα. Hydrodynamic
as well as intramuscular injections were used for the experiments in
mice and intramuscular electroporation for the experiments in macaques.
Plasma levels of IL‑15 were higher when mice received vectors encoding
IL‑15/IL‑15Rα than when they received the vector for IL‑15 only. The
data also show that the resultant IL‑15/IL‑15Rα is active in mice and
macaques. The levels of DNA transfected did not cause toxicity.

Dr. Pavlakis recapitulated his progress in preparation for the clinical
trial of IL‑15/IL‑15Rα. A single plasmid producing both molecules has
been developed, sequenced, and tested in mice and macaques for
expression levels and bioactivity. Concept sheets have been developed in
collaboration with Dr. Lauren Wood for a clinical trial in melanoma. The
proposed clinical trial is a Phase I, single-agent, dose-escalation
study with safety as the primary endpoint; the plasmids would be
transfected intratumorally. Dr. Pavlakis has contacted several companies
to select the appropriate equipment for electroporation. The design of
the clinical trial is based on ongoing trials with IL-2 or IL-12
plasmids in melanoma. Finally, Dr. Pavlakis presented a comparison of
production cost estimates for one or two vectors provided by different
vendors.

The CEI SC considered that intratumoral transfection might not be the
optimal route to administer the IL‑15/IL‑15Rα vectors, as the effect
would be local rather than systemic. The CEI SC was also concerned that,
independently of the route used, DNA delivery may yield IL-15 plasma
levels that are too low to have a biological effect. Dr. Pavlakis
reported that the levels obtained in macaques are up to 70 pg/ml, and
this is similar to the range that is measured in humans after
lymphoablation. Since experiments in mice show that less than 1% of
IL-15 appears in the plasma after intramuscular DNA injection, the
estimated level of IL-15 at the site of injection should be more than
enough for bioactivity. Additional available DNA vectors may increase
plasma levels by more than 5 fold. The CEI SC recommended that Dr.
Pavlakis administer the vectors encoding IL‑15/IL‑15Rα and
IL‑15/sIL‑15Rα to macaques in the same way he envisions administering
them in the clinic to determine the maximum IL-15 plasma levels that can
be achieved and whether these levels are sufficient to have an effect.
Dr. Pavlakis will also conduct tumor graft experiments in mice with the
B16 melanoma model to assess antitumor effects of IL‑15/IL‑15Rα. The CEI
SC also discussed how the vectors could be used in combination with
cancer vaccines. Upon receipt of further results the CEI SC would be
interested in hearing an update on this approach.

*cancer and Inflammation* conference

Dr. Trinchieri presented the program of the CEI-sponsored *Cancer and
Inflammation* conference, which will be held on October 9-10, 2007, at
the Masur Auditorium. The conference has been advertised in the June 26,
2007, issue of the *NCI Cancer Bulletin*. Interested investigators can
register at http://web.ncifcrf.gov/events/cancerandinflammation.

trans-nih initiative in autoimmunity, immunity, and inflammation

Dr. Trinchieri updated the CEI SC on the progress to implement the
Trans-NIH Initiative in Autoimmunity, Immunity, and Inflammation as part
of the NIH Intramural Roadmap. Dr. Ellias Zerhouni, NIH Director, has
appointed Dr. Neal Young, National Heart, Lung, and Blood Institute, to
lead this effort. Drs. Trinchieri and Ron Germain (NIAID) and a Steering
Committee including representatives from several Institutes are also
involved. The Initiative is expected to crystallize in the formation of
an Immunology Center, which may be located in Building 15.

The meeting adjourned at 4:35 p.m.

**Next Meeting: September 24, 2007**

**Location: Not yet confirmed**