IL2 Immunotherapy in HIV1 Infection: Oscillating from Bench to Clinic

1
IL-2 Immunotherapy in HIV-1 Infection
Oscillating from Bench to Clinic

• Irini Sereti, MD MHS
• Clinical and Molecular Retrovirology Section
• Laboratory of Immunoregulation
• National Institute of Allergy and Infectious
  Diseases

2
Interleukin-2 Update

• Characterization of a unique subset of naïve CD4
  cells that expand with IL2 (CEN,
  cytokine-expanded naïve)
• Factors influencing CD4 responses to IL-2
  immunotherapy
• Treatment interruption studies IL-2 as an
  ARV-sparing agent, rationale and trial design
• Responses to IL-2 in the presence of viremia
• Future study directions

3
Interleukin-2 in HIV Infection

• T cell growth factor
• FDA approved in US for metastatic renal cell
  carcinoma and melanoma
• Trimeric receptor a (CD25), b (CD122), gc
  (CD132) chains
• Functional receptors abg (high affinity) and bg
  (intermediate affinity)
• Studied extensively in randomized phase II
  studies in HIV infection both as IV and SQ
  administration
• Intermittent cycles of 3.5-7.5 MIU bid SQ

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Pooled Analysis of CD4 Cell Count Changes in
Vanguard Study
Mean CD4 cell Difference
at 24 weeks
IL-2 Dose (MIU)
5
Observations From Phase II Studies

• Intermittent IL-2 increases CD4 cell counts with
  a strong dose-response relationship
• Toxicity is route (IVgtSQ) and dose dependent
• After an initial induction therapy to increase
  CD4 cell counts, less intensive maintenance
  therapy can be used to maintain counts.
• IL-2 does not lead to long-term increases of
  viral load
• Stellbrink et al AIDS. 2002 Jul
  2616(11)1479-87
• Abrams et al. JAIDS 2002 129(3)221-31
• Davey et al. JAMA 2000284(2)183

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Mean CD4 Counts During the Randomized and Open
Phases of a Controlled Trial of IL-2
IL-2ARV
ARV
Kovacs, et al 1996, NEJM
7
NIAID Long-term Cohort
Farel et al. Blood, 2004
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Questions about the New CD4 T cells

• Are the expanded CD4 cell functional?

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Phase III Studies

• ESPRIT
• (Evaluation of Subcutaneous Proleukin in a
  Randomized International Trial)
• CD4 ? 300
• Sample size 4000, 23 countries
• Follow-up 4 years
• SILCAAT
• (Study of recombinant IL2 in patients with Low
  CD4 Counts under Active Antiretroviral Therapy)
• CD4 50-299, VLlt10,000 copies/ml
• Sample size 2000, 11 countries

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Questions about the new CD4 T cells What can
the lab answer?

• Phenotype
• Origin
• Clonality
• Turnover
• In vitro function

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IL-2 Leads to Increases of CD4/CD25 T Cells
Without Changes in CD4/CD25- T Cells
IL-2 Group
Control Group
p0.7
CD4 T cells/ µl
plt 0.001
CD4/CD25- T cells
CD4/CD25- T cells
CD4/CD25 T cells
CD4/CD25 T cells
Sereti et al, Blood. 2002
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IL-2 Leads to Long-term Decreases in CD4 T Cell
Proliferation
IL-2
IL-2
Control
Control
Percent CD8 T cells expressing Ki67
Percent CD4 T cells expressing Ki67
?
?
plt 0.01
plt 0.01
plt 0.001
p0.3
Month 0
Month 12
Month 0
Month 12
Sereti et al. Blood, 2004
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CD4/CD25 T Cell Increases Induced by
Intermittent IL-2 Strongly Correlate With
Decreases in T Cell Proliferation
Percent change in CD4/CD25 T cells expressing
Ki67
r -0.9, plt0.001
Percent change in CD4/CD25 T cell counts
Sereti et al, Blood. 2004
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Cytokine-expanded Naïve CD4 T cells

• CD4/CD45RO-/CD25

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(No Transcript)
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Recent Thymic Emigrants?
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Separation of Naïve CD4 T cells into CD25 and
CD25-subsets
Sereti et al, JCI. 2005
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CD4/CD45RO-/CD25 Cells Are the Product of
Peripheral Expansion
sjTREC copies/ 106 CD4 cells
Plt0.01
CD45RO-/CD25-
CD45RO-/CD25
CD45RO
Plt0.01
Sereti et al, JCI. 2005
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Reversion?
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CD4/CD45RO-/CD25 and CD25- Cells Have Similar
Proviral DNA and TCR Repertoire Patterns
Proviral DNA copies/ 106 cells
CD45RO-/CD25-
CD45RO-/CD25
CD45RO
Sereti et al, JCI. 2005
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What Is the Apoptosis of CEN Compared to
Conventional Naïve or Memory Cells?
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CEN Cells Have Low Apoptosis Rates
CD45RO-/CD25-
CD45RO-/CD25
CD45RO
0.18
3.13
0.048
0.97
0.12
0.85
Spontaneous
7-AAD
12.7
84
1.58
97.4
1.89
97.1
0.15
0.79
0.11
0.78
0.18
8.84
Anti-CD95
2.39
96.7
1.98
97.1
23.1
67.8
Annexin V
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Are CEN a Functionally Distinct Subset?
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Phenotypic Changes of CD4 T Cells After IL-2
Baseline
Month 12
CD25
CD45RO
Sereti et al, JCI. 2005
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CEN Cells Make Less IL-2 Than Conventional Naïve
Cells
Anti-CD3
P0.001 N11
Percent producing IL-?
Net CPM
CD45RO-CD25
CD45RO-CD25-
CD45RO
CD45RO-CD25
CD45RO-CD25-
CD45RO CD25high
Sereti et al, JCI. 2005
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Do CEN Cells Express Foxp3 and Do They Suppress
As Treg Cells?
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CEN Cells Express Foxp3 at Lower Levels Than Treg
Cells
IL-2 patients
HIV- controls
Relative FoxP3 expression
CD45RO- CD25-
CD45RO-CD25
CD45RO CD25-
CD45RO CD25high
Sereti et al, JCI. 2005
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CEN Cells Can Only Exert Weak Suppression of
Naïve CD4 T Cells
Added subset
CD45RO-/CD25-
1 2 ratio
11 ratio
CD25
Cell number
CD45RO/CD25high
CD45RO-/CD25
CD45RO
Sereti et al, JCI. 2005
CFSE
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CEN Cells Are Not Treg Cells
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Some Conclusions (I)

• IL-2 leads to polyclonal peripheral expansion of
  a novel subset of naïve cells that express CD25
• These cytokine-expanded naïve (CEN) T cells have
  distinct phenotypic and functional properties and
  low apoptosis
• CEN cells express FoxP3 but are weak suppressors
  compared to Treg cells, suggesting a possible
  role in regulation of naïve T cell pool
  homeostasis

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What factors influence CD4 T cell increases after
IL2?
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Lack of CD4 Response to IL2

• A subset of patients fail to respond to IL-2
  therapy after three initial cycles.
• A lower baseline and nadir CD4 count, as well as
  older age have been associated with lower CD4 T
  cell responses.
• The mechanisms of lower responsiveness to IL-2
  are unclear.
• The biologic effects of IL-2 on the T cell pool
  of patients who do not experience CD4 expansions
  have not been characterized.

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Hypothesis

• Too little (quantitative) absence of a specific
  subset in the T cell pool that can respond more
  favorably to increased proliferation (? or ?
  after IL-2?)
• Too much (qualitative?) increased immune
  activation that antagonizes IL-2 main mechanism
  of action (? or ? after IL-2?)

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Matched Case-Control Study of IL2 Non-Responders

• Cases (NR) CD4 count increases at month 6 (after
  3 cycles) less or equal to 10 from baseline
• Controls (R) CD4 count at month 6 more or equal
  to 150 of baseline CD4 count
• Cases and controls matched by study and baseline
  CD4 count
• CD4, CD8 T cell counts, VL, age, nadir CD4 count
  available at baseline

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Cohort Characteristics
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Comparisons Between Cases and Controls at Baseline

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Cases Had Lower TREC Content and Higher T Cell
Proliferation than Controls
P0.02
P0.02
P0.02
P0.02
sjTREC copies/106 T cells
Percent T cells Ki67
CD4
CD4
CD8
CD8
Cases
Controls
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T Cell Naïve and Memory Subsets Did Not Differ
Significantly Between Cases and Controls
CD4
CD8
T cells/ µl
Naive
CM
EM
E
Naive
CM
EM
E
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Although Cases Have No CD4 Increases, Are There
Changes in the T Cell Pool After IL-2?

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TREC T Cell Content Remained Unchanged in Cases
but Decreased Significantly in Controls
P0.002
P0.5
CD8
CD4
sjTREC copies/106 T cells
41
Expression of Ki67 Decreased in T Cells of Both
Cases and Controls
CD8
CD4
P0.3
P0.03
Percent Expressing Ki67
P0.001
P0.04
Cases
Controls
Cases
Controls
Baseline
Post-IL2
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Decreased Activation and Increased CD25
Expression Were Seen in the CD4 T Cell Pool of
the Cases After IL-2 Therapy
CD4
CD4
Plt0.001
P0.04
Plt0.001
Percent HLA-DR/CD38
Plt0.001
Percent CD25
Cases
Controls
Cases
Controls
Baseline
Post-IL2
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Conclusions (II)

• Increased levels of immune activation at baseline
  may significantly impair or delay IL2 responses
• The lack of TREC dilution in patients without CD4
  T cell expansions may be related to less robust T
  cell proliferation or possibly to preferential
  survival of TREC-enriched subsets
• Despite the lack of CD4 T cell count changes,
  IL2-induced biologic effects are clearly noted
  in the T cell pool (CD25, decreased activation)

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IL-2 As an ARV-sparing Agent

• ARV interruptions can lead to significant CD4 T
  cell decreases
• Main predictors of prolonged TI nadir and
  baseline CD4 counts
• IL-2 increases CD4 counts by prolonging their
  survival (decreasing T cell turnover)

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ICARUS ARV Interruption Study in IL-2
Experienced Patients

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Icarus Study Design
Metabolic substudy
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IL-2 Maintains CD4 Counts During HAART
Interruptions- Interruption Group
ARV
CD4 T cells/ml
Month of Study
IL-2
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Viral Load Kinetics During HAART Interruption-
Interruption Group
ARV
HIV-RNA (log copies/ml)
Month of Study
IL-2
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Emergence of Viremia Blunts but Does Not Abrogate
IL2-induced CD4 T Cell Expansions
P0.002
P0.18
P0.02
Pgt0.5
Plt 0.001
Plt 0.001
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CD4 T Cell Increases Are Higher on Continuous ARV
Therapy
P0.03 n25
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CD4 Expansions in Both on and off IL2 Cycles
Correlate With CD4/CD25 T Cell Increases
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CD4 T Cell Increases Correlate With Decreases in
Ki67 Expression That Are Counteracted by Viral
Load ?
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Beyond Icarus
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IL-2 As an Antiretroviral Sparing Agent in IL-2
Naïve ILIAD(E)

• Randomized 11 controlled open label

HAARTIL2
X
CD4gt 500 VLlt 50 HAART
Restart HAART if CD4lt 350
X
HAART
Week 24
Week 72
Week 0
Primary end point proportion of subjects
remaining off HAART at week 72
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ACTG 5102Pablo Tebas

• An Open-label, Pilot Study Utilizing CD4 T-cell
  Counts lt350 Cells/Mm3 as the Threshold for
  Restarting Therapy with Potent Antiretroviral
  Therapy /- Interleukin-2 to Determine the Effect
  of Pulse Therapy on the Characteristics of
  Treatment Interruptions

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Step1. ART
Step 2. No ART
IL2
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Conclusions (II I)

• IL-2 could be used in the setting of ARV
  interruptions to prevent CD4 losses, long-term
  safety and efficacy unclear
• IL-2 is counteracting HIV-induced immune
  activation and the net effect leads to CD4
  changes
• ?IL-2 as a strategy to defer ARV initiation
  (STALWART)

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Future directions

• In vivo fate of CEN cells/ ?true Treg
• IL-2 and potential re-population of GALT
• Does IL-2 have a potential role in therapeutic
  immunizations?
• Does IL-2 have a role as an adjuvant in salvage
  therapeutic regimens?

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Acknowledgments
OP-8 Clinic NIH Patients and staff
CMRS lab Hector Martinez-Wilson
Kara Anthony
Sarah Wynne Meena
Ramchandani Sherita Chapman Chris
Keh
NIAID-LIR Cliff Lane Richard
Davey Joe Kovacs Jorge
Tavel Barbara Hahn Jean Shen
Rosanne Burke
Julia Metcalf Dean Follmann Claire
Hallahan Bill Blackwelder
SAIC Frederick Hiromi Imamichi Tom
Imamichi Raj Natarajan
ANRS Yves Levy Genevieve Cheve
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Sherita Chapman
Meena Ramchandani
Sarah Wynne
Kara Anthony
Chris Keh
Jean Shen
Rosanne Burke
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Questions?