Transcript Childhood Leukemias - Leukemia Trials from University of

Final Thoughts
-Overall, outcomes in ALL have come a long
way since the sixties
-Although we can achieve dramatic and
sustained responses in childhood ALL,
drug refractory relapse is a problem,
especially in adults and high risk groups
-We need drugs that can sustain remission
or effectively treat relapse
-Transplant is risky, particularly in adults
Immunobiology of ALL
-Monoclonal Abs have revolutionized the
analysis and diagnosis of leukemias by
recognizing specific cluster determinants
on the cell surface
-Investigators found that these same
antibodies can selectively deliver therapy
to leukemia cells in vivo
-The accessibility of hematopoietic
malignancy is favorable for this approach
MAbs Commonly Used in Leukemia
Immunophenotyping
T-Cell
– CD1, CD2, CD3, CD4, CD5, CD7, CD8, CD10
B-Cell
– CD10, CD19, CD20, CD22, CD79a
Myeloid
– CD11, CD13, CD14, CD15, CD33
Non-lineage
– CD34, CD38, HLA-DR, CD45
These MAb are used to identify ALLs of
T-cell, B-cell, and mixed lineages.
Why direct a molecule with
anti-CD22 and anti-CD19
-Studies in mice showed that the combination was
better than the individual antibodies
-A mixture of anti-CD22 and anti-CD19 ricin
immunotoxins were developed and showed
promise in phase 1 studies
-A genetically engineered monospecific anti-CD22
immunotoxin recently tested in a phase 2 study
for Hairy Cell Leukemia >60% complete response
rate.
-Our own data has been quite convincing.
VH
VH
VH
VL
VL
VL
CH1
CH1
s
s
Conventional
Antibody
CL
Hinge
s
s
s
s
s
s
s
s
s
s
VH
DT2219
BLT
VL
Toxin
sFv
CH2
CL
Anti-CD22sFv
VL
VH
Anti-CD19sFv
The Process
-Splice genes together and then express in
inducible competent bacteria
-Lyse bacteria, extract and purify protein
-Test protein against
CD22+CD19+
Daudi or Raji
B Lymphoma Cells.
95 kDa
-Vial drug cGMP
-File pre-IND
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Bispecific Ligand Directed
Toxins (BLT) as a Solution
-Powerful, catalytic inhibitors of protein synthesis
-Mechanism of action very different from chemo. Thus, can
be given when chemo can no longer be given
-Criteria for a successful BLT:
*Bispecific has greater activity than its monospecific
counterparts
*Bispecific is superior to a mixture of the
monospecific counterparts indicating an
advantage of both ligands on the same molecule
-Genetically modifiable
Genetic engineering used to increase affinity and
product yield and diminish immunogenicity
BioAssay - Proliferation
A. DT22 + DT19 Mixture
125
100
DT2219
IC 50 = 0.15
75
% Control
Response
DT22
IC 50 = 3.05
50
DT19
25
0
0.01
DT22 + DT19
IC 50 = 3.8
0.1
100
10
1
nM
B. HPBMLT
125
100
100
75
% Control
Response 50
DT2219
BIC3
IC50=.015
25
0
0.01
C. Daudi
125
75
50
DT2219
IC 50 = 0.06
25
0.1
1
nM
10
100
0
0.01
DT2219G53E
0.1
1
nM
10
100
Therapy of Scid Mice With Systemic
Cancer Given DT2219
Measure
SURVIVAL
Day 0
Inject IV 106 Cells
Day 3
Start Treatment
In press:
Leukemia Research
Sensitive Detection of B Cell Malignancy
in Scid Mice in Real Time
Raji Cancer Cells
-Transfect
Luciferase and
GFP genes
DUAL REPORTERs!
Clone via FACS
To obtain stable
transfectant
-The bioluminescent reaction releases light
and the light signal can be used for analyte quantification
-Use
a very sensitive photon detector which can detect the emission of even a
few photons
-GFP is fluorescent! Must use a different detector. Different information
Conclusions
- BLTs are highly effective in inhibiting malignant B cells.
-Our BLT is selective, potent, and capable of curing mice
with systemic human B cell cancer.
-The combination of both sFvs on the same single chain
molecule are necessary for the high degree of
effectiveness of DT2219.
-A clinical batch has been prepared and FDA IND approved
for testing at Scott and White
-Since this DT is an established inhibitor of protein
synthesis, DT2219 may be valuable as alternative drug
therapy to sustain remission or treat relapse
-If immunogenicity is a problem in our trial, we have found a
solution.