Download Slides

Gene and immunomodulatory
therapies to disable latent HIV
Keith R. Jerome, MD PhD
Fred Hutchinson Cancer Research Center
University of Washington
July 20, 2015
Why is cure of HIV so difficult?
•HIV integrates into the genome of infected cells
•Latency is established in long-lived memory T cells (Tcm, Tem, Tscm)
•Long-term reservoir consists of ~107 latently infected cells
•If suppressive therapy is stopped, virus quickly rebounds from the latent reservoir
DE Kaufmann PLoS Med 2004
Take home message
Cell-, gene-, and immunotherapies for HIV are
highly promising; many are in clinical trials and
some have already shown anti-viral activity
Outline
•
•
•
Reduction of the HIV reservoir
•
Transplantation
•
Immunotoxins
•
Disruption of provirus
Control of viral reactivation
•
Genetic protection of T cells
•
CCR5 disruption
•
CAR T cells
•
vectored antibodies
•
Immune modulations
Concluding thoughts
The latent reservoir presents a substantial hurdle to cure
Participa
nt
Sex
Ag
e
Time of
initiation of
ART
Duration
of ART at
time of
study
(yrs)
ART at
time of
study
CD4 cell
count at
time of
study
(cells/μl)
CD8 cell
count at
time of
study
(cells/μl)
CD4/CD8
ratio
Plasma
HIV RNA
at time of
study
(copies/
mL)
Level of
HIV DNA
in blood
(copies/
106 cells)
Level of
infectiou
s HIV in
blood
(/106
cells)
Level of
HIV DNA
in
sigmoid
colon
(copies/
106 cells)
1
Male
44
Chronic
8.6
ABC/3TC/
EFV
410
580
0.7
<50
<2.56
0.05750
89.0
2
Male
46
Early
10.5
ABC/3TC/
EFV
1060
840
1.3
<50
<2.56
0.00064
<2.56
TW Chun AIDS 2010
Cure may not require complete elimination of the
latent reservoir
AL Hill, PNAS 2014
Types of HIV cure
•
Sterilizing cure (the Berlin patient): no traces of replication
competent virus can be found in patient
•
Functional cure: virus can be found by sensitive testing, but
controlled at extremely low levels without the need for
continued therapy
•
Remission: control of virus at extremely low or undetectable
levels for an extended period, followed by subsequent viral
recurrence
Hematopoietic Cell Transplantation
•
•
•
•
HIV predisposes to leukemia and lymphoma
Consequently, some HIV patients require bone or stem cell transplantation
Myeloablative conditioning and chemotherapy kills cells comprising the latent HIV reservoir
How effective is this?
V Avettand-Fenoel AIDS 2007
Thus, transplantation alone is not sufficient to cure HIV
Allogeneic transplantation
•
Graft-versus-host disease (GVHD) is a common complication
of allogeneic transplantation
•
Since the HIV reservoir is recognized as foreign by the
transplanted immune system, there is also a graft-versusreservoir (GVR) effect
•
Could allogeneic transplantation, combined with suppressive
antivirals during engraftment, lead to cure?
Graft versus reservoir - the Boston patients
•
Allogeneic transplants, in combination with continual antivirals throughout
engraftment period
•
GVHD contributed to a substantial reduction of the HIV reservoir
TJ Henrich J Inf. Dis. 2013
•
Is the reservoir eliminated? Are these patients cured?
The Boston patients
•
Analytical treatment interruption at 4.3 and 2.6 years post-transplant
TJ Henrich
Annals Int Med 2014
•
Graft-versus-host can substantially reduce the size of the HIV
reservoir, but does not seem adequate to eliminate it
Immunotoxins
www.pvanuden.com
PW Denton PLoS Pathogens 2014
•
Latently infected cells may not be completely quiet; occasionally go through
low-level reactivation
•
Can this be exploited for elimination of such cells?
Targeted mutagenesis of integrated provirus
•
Targeted endonucleases allow specific disruption of specific gene targets
•
Knockout can be directed toward essential viral genes
JT Schiffer J Virol 2012
Aubert PLoS ONE 2011
Targeted deletion of integrated provirus
W Hu PNAS 2014
•
Cure requires disruption of a substantial majority of integrated virus
•
No in vivo delivery system currently available approaches 100% in memory T cells
Cure may not require complete elimination of the
latent reservoir
AL Hill, PNAS 2014
Cure may not require complete elimination of the
latent reservoir
JM Conway, PNAS 2015
Protection of T cells – gene
therapy
• Trans-dominant Rev (Rev M10)
• Rev M10 plus antisense TAR
• Antisense Env
• Ribozymes
• Fusion inhibitors
• Combination restriction factors
Genetic protection of T cells
antisense Envelope
Rev M10 plus antisense TAR
RA Morgan Hum Gene Ther 2005
BL Levine PNAS 2006
Genetic protection of T cells
antisense Envelope
P Tebas Blood 2013
Genetic protection of T cells
entry inhibitor C46
J van Lunzen Mol Ther 2007
Natural protection of T cells CCR5D32
•
CCR5 is a critical co-receptor for HIV entry
•
CCR5 is dispensable for normal immune cell development and function
•
CCR5D32 is a naturally occurring variant conferring resistance to HIV infection
•
homozygous CCR5D32 is observed in ~1% of northern Europeans; less
common in other populations
Tilton and Doms Antiviral Res 2010
Transplantation from CCR5D32 donor
•
This is the procedure that led to the cure of the Berlin patient
•
Cure presumably resulted from some combination of conditioning,
graft-versus-reservoir, and lack of susceptible cells if reactivation
occurred from any reservoir remaining
•
Since CCR5D32 is rare, it is difficult to identify appropriately matched
donors with CCR5D32
•
Subsequently performed in several other patients, but no additional
cures documented yet
CCR5 disruption
•
The gene encoding CCR5 can be targeted for disruption in a patient’s own cells
•
Can use targeted endonucleases (ZFNs, TALENs, CRISPRs, or meganucleases) to induce
mutation in CCR5
•
CCR5 can be disrupted in stem cells or mature T cells
•
CXCR4, the other major co-receptor for HIV, is required for immune cell development
and thus can’t be disrupted in stem cells, but disruption tolerated in T cells
HP Kiem Cell Stem Cell 2012
P Tebas NEJM 2014
Chimeric antigen receptor (CAR) T cells
• Allow T cells to recognize surface antigen without
need for MHC
• Anti-CD19 and other CAR T cells are providing
dramatic responses in leukemia
• Clinical trials have been performed with anti-HIV CAR
T cells
• CAR T cells persist in HIV patients
• Clinical benefit has been difficult to document, but
published studies used early-generation CAR T cells
Mitsuyasu
Deeks
Aronson
M Casucci J Cancer 2012
J Scholler Sci Transl Med 2012
•
Latently infected cells are not completely quiet; occasionally go through low-level reactivation
•
Can this be exploited for elimination of such cells?
Vectored delivery of antibodies or antibody-like molecules
Adeno-associated virus (AAV) transduction of muscle allows durable transgene expression
CE Deal Curr Opin HIV AIDS 2015
MR Gardner Nature 2015
Immune modulation
•
Therapeutic vaccination
•
Adjuvants
•
TLR (4/7) stimulation
•
Cytokines (IL-7, IL-15)
•
Reversal of immune exhaustion - PD1 pathway blockade
Closing thoughts on HIV cure and
the role of cell-, gene-, and immunotherapy
• Cell-, gene-, and immuno-therapy offer an almost unlimited
number of avenues by which to attack HIV
• Many of these ideas are in clinical trials, and some have
already shown antiviral activity
• Combination approaches are likely to be critical – not only
combinations of gene therapies and immune modulations,
but also combinations with manipulation of latency
• Functional cure and remission are useful concepts – even
extended viral control in the absence of antivirals is likely to
be beneficial
Acknowledgments
Caladan Foundation