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(4) CO-STIMULATORY AND VARIED AGENTS
Anti-Interleukin-10
Presenter: Theresa Whiteside, Ph.D.
According to Dr. Whiteside, much is known
about IL-10, and antibodies to IL-10 are already used to treat systemic lupus erythematosus (SLE) and rheumatoid arthritis. Nevertheless,
only preclinical data are available regarding its effects in cancer.
The potential clinical
use of IL-10 antibodies in cancer treatment would be based on neutralization of
IL-10, which is known to exert direct growth-inhibitory effects on tumor cells in vitro
and in vivo, to serve as a growth factor for B lymphoma
and melanoma cells, and to both stimulate and suppress immune cells. IL-10 is
produced by tumor cells, B-cells, tumor-associated macrophages, tumor-infiltrating
lymphocytes, and Tregs in tumors or the blood of
cancer patients.
This cytokine is pluripotent,
signaling through STAT1 and STAT3 in most cells, but also involving other
pathways. In vitro, antibodies to IL-10 sensitize tumors to
chemotherapeutic drugs. IL-10 may be anti-apoptotic, perhaps by modulating
BCL2.
In a murine lupus
model, constant IL-10 antibody administration protected the animals from
autoimmune effects and prolonged survival, whereas IL-10 accelerated the onset
of autoimmunity.
Dr. Whiteside summarized
clinical experience with anti_IL-10 antibodies. In a pilot study, murine antibodies were given to six steroid-dependent SLE
patients for 21 days. No serious adverse events were reported, and clinical
improvement was observed in all patients. Monoclonal antibody levels remained
higher during treatment than levels of IL-10, suggesting that endogenous IL-10
was being neutralized. Although the patient IL-10 levels remained higher after
therapy than those of normal subjects, they were lower than at baseline.
The potential for
humanized, clinical-grade anti_IL-10 could involve many different settings and
tumor types. Such antibodies could be used in multiple therapy regimens. Many
independent clinical investigators would likely be interested in having access
to them.
It might first be
necessary to separate anti_IL-10 immunosuppressive effects from its immunostimulatory activities before contemplating the use
of antagonists. Theoretically, anti_IL-10 could be used to sensitize resistant
tumors to chemotherapeutic drugs. Other potential uses include elimination of Tregs (which produce a great deal of IL-10), direct
inhibition of tumor proliferation, up-regulation of antigen process in APCs,
down-regulation of tumor-associated inflammation, and elimination of tumor
escape. Dr. Whiteside noted that DCs produce a great deal of IL-10 and they
might contribute to the development of Tregs. The use
of antibodies might defuse the activity of the IL-10_producing DCs.
Discussion
Dr. Berzofsky
pointed out that one of the important functions of IL-10 is to block IL-12
production by dendritic cells, so blockade of IL-10
would be expected to increase IL-12 and interferon-gamma production and thus
the stimulation of Th1 cells. Anne O’Garra has
described a type of Tregs that make and also respond
to IL-10. She and Giorgio Trinchieri have found that
anti_IL-10R is effective at potentiating a vaccine. Dr. Berzofsky
also mentioned that he had observed an ability of IL-10 in vitro
to stimulate CTLs.
Dr. Pardoll
said that this is an interesting but complex agent, and he asked if anyone has
investigated the role of IL-10 in Treg suppression of
antitumor activity. IL-10 blockade diminishes the Treg
effect. Dr. Whiteside said that this question has been studied in vitro
but not in vivo. Several participants asked whether anyone has
looked at the IL-10 message in Tregs in, for example,
ovarian cancer. Dr. Palucka was particularly
interested to know if such studies have been done with antigen-specific Tregs. No one was aware of any such studies. Dr. Whiteside
spoke about expression of IL-10 by tumor-infiltrating lymphocytes from human
tumors. Dr. Pardoll said that anti_IL-10 has some
potential but more investigation is needed.
Dr. Amy Rosenberg said that anti_IL-10, at
least in the pilot study, appears to decrease autoimmunity; however, in a
cancer-therapy setting, an autoimmune response would be desirable. She asked
why this agent would be worth pursuing. She mentioned that a STAT3 knockout in
CD4+ cells abrogates autoimmunity in the EAE model. Dr. Pardoll
said that just because the antibody abrogates autoimmunity does not necessary
imply that it will eliminate antitumor activity, but it does raise questions.
Dr. Berzofsky
asked why anti_IL-10 receptor is not on the list. It might be better to block
the receptor. Dr. Cheever said that it was not submitted as a candidate to the
Web site. Nevertheless, this might be a pathway worth investigating.
Dr. Disis said it
appears that the candidate agents fall into two categories: those with
interesting but scant data and those with a sizeable amount of preclinical and
clinical data. Anti_IL-10 falls into the former group.
References
·
Vicari AP, Trinchieri G.
Interleukin 10 in viral diseases and cancer: exiting the labyrinth? Immunol Rev, 202:223-236, 2004.
·
Llorrente L, Richaud-Patin Y,
Garcia-Padilla C, et al. Clinical and biologic effects of anti-interleukin-10
monoclonal antibody administration in systemic lupus erythematosus.
Arthritis Rheum, 43(8): 1790-1800, 2000.
·
Ishida H, Muchamuel S, Sakaguchi S, Andrade
S, Menon S, Howard M. Continuous administration of
anti-interleukin-10 antibodies delays onset of autoimmunity in NZB/W F1 mice. J
Exp Med, 179:305-310, 1994.
·
Taylor A, Verhagen J, Blaser K, Akdis M, Akdis CA. Mechanisms of
immune suppression by interleukin-10 and transforming growth factor-ȕ:
the role of T regulatory cells. Immunology, 117:433-442, 2006.
Anti_LAG-3 and sLAG-3
Presenter: Elizabeth Jaffee, M.D.
Lymphocyte activation gene-3
(LAG-3 or CD223) is a negative regulator of activated T cells. Little is known
about anti_LAG-3 or soluble LAG-3 fragment (sLAG), although they are very interesting agents. Only a
few groups have been studying them. A colleague of Dr. Jaffee’s
at Johns Hopkins has shown that the agent has cell-intrinsic function and seems
to signal through erk. LAG-3 is expressed on
activated natural killer and T cells, but not on resting lymphocytes. It is
selectively up-regulated on Tregs and is involved in
mediating Treg function in murine
models. sLAG-3 is released by activated T cells and is
found in serum.
Rat anti-mouse LAG-3 blocks LAG-3 function
without interfering with its ability to bind to MHC class II molecules in vitro.
It blocks Treg activity in vitro
and enhances T-cell expansion in vivo. It has a potential role as a check inhibitor
by blocking Tregs. Anti_LAG-3 has been shown in two
tumor models to block Treg activity.
sLAG-3
has a role in T-cell migration. It has been used in two phase I studies. Because
it induces secretion of certain chemokines and Th1
cytokines needed for DC migration to secondary lymphoid organs, it could be a
candidate adjuvant for cancer vaccines.
Two phase I studies have assessed safety and
T-cell responses using sLAG-3 (IMP321) as an adjuvant to influenza or hepatitis
B vaccines. In the influenza vaccine study, 40 normal volunteers were randomly
assigned to receive flu vaccine in one of three doses of sLAG
as adjuvant or a saline control. No differences were seen in post-vaccination humoral responses measured at day 29 or 57. The subjects
who received the sLAG adjuvant had higher levels of
Th1-type flu-specific CD4+ T-cell responses, however. sLAG-3
was well tolerated and is currently being evaluated in a phase I trials in metastatic
renal cell carcinoma, breast carcinoma, and disease-free melanoma patients.
sLAG-3 is being produced by a company in France. It
might have some potential as a cancer vaccine adjuvant for priming the immune
response. Anti_LAG-3 has shown some activity in preclinical models as a
checkpoint inhibitor, but would probably be better used in combination with a
vaccine. Anti_LAG-3 appears to be more interesting but it has not been tested
in cancer models. More data are needed about this molecule.
Discussion
Dr. Disis
said that the lack of difference between the groups in the influenza vaccine
study seems to indicate that sLAG does not hold a
great deal of interest. She suggested eliminating sLAG
from consideration but retaining the antibody. Dr. Pardoll
indicated that another group did not find any evidence that LAG-3 can activate
DCs.
Most agreed that LAG-3 seems to be at a “more
primitive level.” Others mentioned the negative prognostic value of elevated
IL-10 and receptor blockade.
By voice acclamation, the participants
determined the priority ranking of the varied agents to be anti_IL-10 and/or
IL-10 receptor, anti_LAG-3, sLAG-3.
References
·
Huang CT, Workman CJ, et
al. Role of LAG-3 in regulatory T cells. Immunity, 21(4):503513, 2004.
·
Andreae S, Piras F, et al.
Maturation and activation of dendritic cells induced
by lymphocyte activation gene-3 (CD223). J Immunol,
168(8):3874-3880, 2002.
·
Triebel F. LAG-3: a regulator of T cell and DC
responses and its use in therapeutic vaccination. Trends Immunol,
24(12):619-622, 2003.
·
Workman CJ, Vignali DA. Negative regulation of T cell homeostasis by
lymphocyte activation gene-3 (CD223). J Immunol,
174(2):688-695, 2005.
·
Brignone C, Grygar C, et al.
IMP321 (sLAG-3) safety and T cell response potentiation
using an influenza vaccine as a model antigen: A single-blind phase I study.
Vaccine, 25(24):46414650, 2007.
·
Fougeray S, Brignone C, et
al. A soluble LAG-3 protein as an immunopotentiator
for therapeutic vaccines: Preclinical evaluation of IMP321. Vaccine
24(26):5426-5433, 2006.
·
Casati C, Camisaschi C, et
al. Soluble human LAG-3 molecule amplifies the in vitro generation of type 1
tumor-specific immunity. Cancer Res, 66(8):4450-4460, 2006.
·
Brignone C, Grygar C, et al.
IMP321 (sLAG-3), an immunopotentiator for T cell
responses against a HBsAg
antigen in healthy adults: a single blind randomised
controlled phase I study. J Immune Based Ther
Vaccines, 5:5, 2007.
·
Liyanage UK, Moore TT, et al. Prevalence of regulatory
T cells is increased in peripheral blood and tumor microenvironment of patients
with pancreas or breast adenocarcinoma. J Immunol, 169(5):2756-2761, 2002.
·
Terabe M, Berzofsky JA. Immunoregulatory T cells in tumor immunity. Curr Opin Immunol,
16(2):157-162, 2004.
Anti–Transforming Growth Factor (TGF)-beta
Presenter: Frank Calzone, Ph.D.
According to Dr. Calzone,
SMAD-dependent TGF-beta signaling is well understood, although alternative
signaling is not. Any antibody or TGF receptor II_based
therapeutic should neutralize TGF-beta without cross-reacting with latent ligand. Dr. Calzone provided a list of various TGF-beta_targeted inhibitors and described preclinical
experience with using them as cancer immunotherapy or as direct antitumor
agents.
Such inhibitors, however, pose some cancer
risks. Inhibiting the SMAD pathway could increase risk of carcinomas that might
become apparent long after drug approval and wide clinical acceptance. As
evidence, Dr. Calzone pointed out that TGF-beta receptor-I and -II, as well as
SMAD4, are frequently inactivated by mutation in human pancreatic and biliary cancers. Also, experimentally, TGF-beta is a
potent, negative regulator of epithelial cell proliferation (normal cells and
non-aggressive cancers).
A number of antibodies
have been raised against TGF-beta. Dr. Calzone pointed out several reasons why
selecting an antibody would be preferable to the huFc
receptor-II. Most importantly, process development for an antibody is
well-defined with high yields (1 g/L) readily achievable. Antibodies have a
better pharmacokinetic profile than the receptor drugs. Safety events
associated with TBR immune recognition are rare but potentially
significant.
A phase I cancer study of
the antibody (GC-1008 manufactured by Genzyme/AstraZeneca)
is under way, whereas no human data are available on the huFc
receptor-II. No results from the study have been published yet. The trial has
the objective of assessing MTD and safety in patients with locally advanced
metastatic renal cell carcinoma or malignant melanoma. Another phase I study by
AstraZeneca has been completed, enrolling 45 patients with early stage,
diffuse, cutaneous systemic sclerosis. More serious
adverse events were reported in the treatment group, but the antibody was
generally well tolerated, and the adverse events were manageable. No efficacy
was shown.
Among the contemplated
uses of anti_TGF-beta would be as a single agent to
amplify or unmask natural immunosurveillance, as an
agent to enhance T-cell adoptive immunotherapy in cancer, or to amplify the efficacy
of an anticancer vaccine aimed at inducing CTL-mediated tumor regression. A
clinical study of TGF beta blockade would require special expertise because
this treatment mode could have multiple effects on tumors (stroma,
tumor, Tregs). The situation would be very
complicated.
Dr. Calzone suggested
that pan-specific TGF-beta neutralizing offers more opportunity to demonstrate
efficacy, and this seems more critical than safety given the available clinical
data. Any trial should generate detailed information on the response of T-cell
subsets to make the connection between TGF blockade and tumor immunobiology versus direct antitumor activity or stroma-mediated tumor inhibition.
Discussion
The participants discussed which agents are in
development and their proposed uses. Some discussion ensued about Genentech’s
activities in this area and the focus on using the agent for various aspects of
fibrosis, e.g., to prevent scarring or collagen deposition.
Dr. Berzofsky
reported that some preclinical work was done in his lab on the immunoregulatory pathway in which natural killer T cells
(NKT) induce myeloid cells to make TGF-beta that inhibited CTL-mediated tumor immunosurveillance. In at least three tumor models, his
group was able to reduce or eliminate metastases or tumor recurrence. The
participants agreed that having an agent to target both the NKT pathway and the
Treg pathway would be very exciting. Dr. Berzofsky is running the first-in-human trial together with
Dr. John Morris of the Metabolism Branch, NCI, in melanoma or renal cell
carcinoma patients. The study has four sites, with NCI as the lead site. It is
a dose-escalation trial; several dose cohorts are already completed. The
investigators are looking at effects on T-cell response and biomarkers. The
primary goal is safety and ascertainment of the MTD, which has not yet been
reached.
Dr. Pardoll
said that TGF is an attractive target. These studies should provide a sense for
the extent to which these effects are immunologic versus non-immunologic. It
would be important to look in a neo-adjuvant setting. A significant body of
preclinical data supports the rationale for use of anti_TGF-beta.
The time would seem to be right to bring TGF beta blockers into the clinic.
Several participants agreed with the latter statement.
Dr. Cheever said that it was difficult to know
how to rank these related agents. Some “heavy hitters” are involved with
development and testing and thus the agents are likely to be broadly available
for testing. Scientific interest in TGF-beta blockade is great. The
participants generally recognized that clinical advancement of TGF-beta
neutralizing antibodies (and TBR kinase inhibitors)
for the treatment of fibrosis and cancer is being addressed by biotech (Genzyme) and pharma (Lilly).
Immediate access to these drugs and funding for clinical trials in tumor
immunology may be difficult.
Dr. Berzofsky said
that the primary sponsor of his trial is Genzyme,
which owns GC1008. He posited that it would be important to test the agent in
multiple cancers, but the theoretical risk of exacerbating the disease has
caused some foot dragging. Trying it in combination with cancer vaccines (e.g.,
prostate cancer vaccine) would also be a very interesting avenue of research.
The pharmaceutical companies would probably be most interested in developing it
as a single agent, but immunologists would probably like to try it in
combinations or as an adjuvant.
The participants expressed greater interest in
the antibody than in the receptor. By voice acclamation, the participants
determined the priority ranking of the varied agents to be anti_TGF-beta,
anti_IL-10 and/or IL-10 receptor, anti_LAG-3, sLAG-3, TGF-beta receptor.
References
·
Gorelik L, Flavell RA. Immune-mediated
eradication of tumors through the blockade of transforming growth factor-beta
signaling in T cells, Nat Med, 7:1118-1122, 2001.
·
Gorelik L, Flavell RA.
Transforming growth factor-beta in T cell biology, Nat Rev Immunol,
2:46-53, 2002.
·
Terabe M., Berzofsky JA. Immunoregulatory T cells in tumor immunity, Curr Opin Immunol,
16:157-162, 2004.
·
Terabe M, et al. Transforming growth factor-beta
production and myeloid cells are an effector mechanism through which CD1d-restricted T cells block cytotoxic T lymphocyte-mediated tumor immunosurveillance:
abrogation prevents tumor recurrence, J Exp Med, 198:1741-1752, 2003.
·
Wahl SM, Wen J, Moutsopoulos N. TGF-beta:
a mobile purveyor of immune privilege, Immunol Rev,
213:213-227, 2006.
·
Yingling JM, Blanchard KL, Sawyer JS. Development of
TGF-beta signalling inhibitors for cancer therapy,
Nat Rev Drug Discov, 3:1011-1022, 2004.
·
Muraoka RS, et al. Blockade of TGF-beta inhibits
mammary tumor cell viability, migration, and metastases, J Clin
Invest, 109:1551-1559, 2002.
·
Nam J-S, et al. Bone sialoprotein mediates the tumor cell-targeted prometastatic activity of transforming growth factor beta
in a mouse model of breast cancer, Cancer Res, 66:6327-6335, 2006.
CD40 Agonists
Presenter: Paul Sondel, M.D., Ph.D.
The two agents considered in this category are
an agonistic recombinant CD40 ligand trimer and a fully human and selective CD40 agonist
monoclonal antibody. The target is the CD40 receptor itself. The goal of using
the agonist is to provide pharmacologically the signal that is physiologically
given by the ligand on the surface of CD40+ helper T
cells, thereby helping antigen-presenting cells (APCs) perform better, and
activating any population of cells bearing CD40 molecules on their surface.
Dr. Sondel
described the main ways the agonist works in preclinical models: through APC
activation and induction of T-cell immunity or by direct tumor inhibition
(especially in CD40-bearing B-cell lymphomas). CD40 agonists can also affect
tumors not expressing CD40 through other mechanisms, such as an anti-angiogenic effects or induction of antitumor innate
immunity. Preclinical studies identified cytokine release syndrome as a
toxicity problem.
Dr. Sondel described
available unpublished and published data on clinical experience, mostly based
on the fully human monoclonal antibody. One phase I trial enrolled 29 patients
with melanoma or other solid tumors. Four subjects had measurable objective
responses by RECIST criteria. Most showed up-regulation of the CD86
co-stimulatory molecule. In one well-studied case, tumor-specific T cells were
induced. Cytokine response syndrome and liver/hematologic toxicity were
reported.
The other molecule that has been tested is the
recombinant human CD40 ligand trimer.
The initial phase I study showed 2 partial responses out of 32 solid tumors or
non-Hodgkin lymphoma. Some 76% of patients had decreases from baseline in the
percentage of circulating CD19 B cells on day 5, possibly related to the
peripheral clearance of these CD40+ cells by binding to the ligand.
The percentage of CD4+ T cells increased during this time in 81% of treated
patients.
Dr. Sondel
speculated that these agents could be used as monotherapy
for induction of innate and adoptive immunity to CD40+ and CD40_ tumors; they
might also be used as single agents for direct inhibition of CD40-expressing
tumors, which includes up to 70% of solid tumors. CD40 agonists have excellent
potential for combination therapy with other anticancer treatments,
including
chemotherapy, radiotherapy, cancer vaccines, toll-like receptor agonists,
cytokines, and TNF receptor_family agonists.
It appears, however, that
no compelling need exists to produce the monoclonal antibodies because the
pharmaceutical industry (Pfizer) is already involved and appears willing to
provide them for investigator-initiated research. The recombinant trimeric ligand was being
developed by Immunex-Amgen, but is no longer;
therefore, it may be a candidate for NCI production or distribution.
Discussion
Dr. Tom Waldmann discussed the potential for desirable effects
involving combination of CD40 agonistic therapy with IL-15, which may lead to
important effects not mediated by IL2. However, IL-15 has a short half life,
and the reagent is not very effective in the absence of IL-15R alpha. By giving anti-CD40 ligand, the IL-15 receptor alpha subunit is induced on DCs
and IL-15 bound to this receptor is recycled, its biological activity is
increased, and its effects are prolonged, possibly for 3 weeks. Thus an added
benefit of CD40 ligation would be the enhancement of treatment with IL-15.
The CD40 signal is a very
important and effective activator of DCs. Drs. Berzofsky
and Mackall have experience using CD40 ligand for maturing human DCs, but it has been unavailable
since it became the intellectual property of Amgen.
Dr. Sondel favors
the antibody because it has several important characteristics, e.g., it has
action on APCs, it can be injected into tumors, and it has an effect on the innate
immune system. He, therefore, advocated giving it a high priority ranking.
Dr. Weber agreed, saying
that demonstration of clinical response plus a sound scientific rationale is a
compelling combination.
A participant inquired about the agent’s mechanism
against B cells. Dr. Sondel said that it induces
apoptosis via the cytokine storm. There was a brief discussion about the
concomitant decrease in peripheral B cells and the possibility that this
decrease is due to migration and not death.
Dr. Schlom
recommended not having both anti-CD40 and the ligand
at the top of the priority list. Dr. Sondel suggested
both are important and have been developed separately. Because the trimeric ligand is not available,
he suggested putting it at the top of the list, just above the antibody. It
would be more expensive to produce than the monoclonal antibody.
By voice acclamation, the
participants determined the priority ranking of the varied agents to be
anti-CD40 and/or CD40L, anti_TGF-beta, anti_IL-10 and/or
IL-10 receptor, anti_LAG-3, sLAG-3 (low priority), TGF-beta receptor (low
priority).
References
·
Bennett SR, Carbone FR, Karamalis F, Flavell RA, Miller
JF, Heath WR. Help for cytotoxic-T cell responses is mediated by CD40 signalling.
Nature, 393(6684):478-480, 1998.
·
Buhtoiarov IN, Lum H, Berke G, Paulnock DM, Sondel PM, Rakhmilevich AL. CD40
ligation induces antitumor reactivity of murine
macrophages via an IFN gamma-dependent mechanism. J Immunol,
174:6013-6022, 2005.
·
Chiodoni C, Iezzi M, Guiducci C, et al. Triggering CD40 on endothelial cells
contributes to tumor growth. J Exp Med, 203:2441-2450, 2006.
·
French RR, Chan HT, Tutt AL, Glennie MJ. CD40
antibody evokes a cytotoxic T cell response that
eradicates lymphoma and bypasses T cell help. Nat Med, 5(5):548-553, 1999.
·
Funakoshi S, Longo DL,
Beckwith M, et al. Inhibition of human B-cell lymphoma growth by CD40
stimulation. Blood, 83(10):2787-2794, 1994.
·
Grewal IS, Flavell RA.
CD40 and CD154 in cell-mediated immunity. Annu Rev Immunol, 16:111-135, 1998.
·
Turner JG, Rakhmilevich AL, Burdelya C, Neal
Z, Imboden M, Sondel PM, Yu
H. Anti-CD40 antibody induces antitumor and anti-metastatic effects: The role
of NK cells. J Immunol, 166(1):89-94, 2001.
·
Van Kooten
C, Banchereau J. CD40-CD40 ligand.
J Leuk Biol, 67(1):2-17,
2000.
·
Vonderheide RH. Prospect of targeting the CD40 pathway
for cancer therapy. Clin Cancer Res, 13(4):1083-1088,
2007.
·
Vonderheide RH, Flaherty KT, Khalil
M, Stumacher MS, Bajor DL, Hutnick NA, Sullivan P, Mahany
JJ, Gallagher M, Kramer A, Green SJ, O’Dwyer PJ,
Running KL, Huhn RD, Antonia SJ. Clinical activity
and immune modulation in cancer patients treated with CP-870,893, a novel CD40
agonist monoclonal antibody. J Clin Oncol, 25(7):876-883, 2007.
·
Vonderheide RH, Dutcher JP, Anderson
JE, Eckhardt SG, Stephans
KF, Razvillas B, Garl S, Butine MD, Perry VP, Armitage RJ,
Ghalie R, Caron DA, Gribben
JG. Phase I study of recombinant human CD40 ligand in
cancer patients. J Clin Oncol,
19(13):3280-3287, 2001.
·
Vonderheide RH, personal communication regarding
unpublished observations, July 2007.