Final ThoughtsFinal Thoughts

-Overall, outcomes in ALL have come a -Overall, outcomes in ALL have come a long way since the sixtieslong way since the sixties

-Although we can achieve dramatic and -Although we can achieve dramatic and sustained responses in childhood ALL, sustained responses in childhood ALL, drug refractory relapse is a problem, drug refractory relapse is a problem, especially in adults and high risk groupsespecially in adults and high risk groups

-We need drugs that can sustain remission -We need drugs that can sustain remission or effectively treat relapseor effectively treat relapse

-Transplant is risky, particularly in adults-Transplant is risky, particularly in adults

Immunobiology of ALL

-Monoclonal Abs have revolutionized the -Monoclonal Abs have revolutionized the analysis and diagnosis of leukemias by analysis and diagnosis of leukemias by recognizing specific cluster determinants recognizing specific cluster determinants on the cell surfaceon the cell surface

-Investigators found that these same -Investigators found that these same antibodies can selectively deliver therapy antibodies can selectively deliver therapy to leukemia cells in vivoto leukemia cells in vivo

-The accessibility of hematopoietic -The accessibility of hematopoietic malignancy is favorable for this approachmalignancy is favorable for this approach

MAbs Commonly Used in Leukemia Immunophenotyping T-CellT-Cell

– CD1, CD2, CD3, CD4, CD5, CD7, CD8, CD10CD1, CD2, CD3, CD4, CD5, CD7, CD8, CD10

B-CellB-Cell– CD10, CD19, CD20, CD22, CD79aCD10, CD19, CD20, CD22, CD79a

MyeloidMyeloid– CD11, CD13, CD14, CD15, CD33CD11, CD13, CD14, CD15, CD33

Non-lineageNon-lineage– CD34, CD38, HLA-DR, CD45CD34, CD38, HLA-DR, CD45

These MAb are used to identify ALLs of These MAb are used to identify ALLs of T-cell, B-cell, and mixed lineages.T-cell, B-cell, and mixed lineages.

Why direct a molecule with Why direct a molecule with anti-CD22 and anti-CD19anti-CD22 and anti-CD19

-Studies in mice showed that the combination was better -Studies in mice showed that the combination was better than the individual antibodiesthan the individual antibodies

-A mixture of anti-CD22 and anti-CD19 ricin immunotoxins -A mixture of anti-CD22 and anti-CD19 ricin immunotoxins were developed and showed promise in phase 1 studieswere developed and showed promise in phase 1 studies

-A genetically engineered monospecific anti-CD22 -A genetically engineered monospecific anti-CD22 immunotoxin recently tested in a phase 2 study for immunotoxin recently tested in a phase 2 study for Hairy Cell Leukemia >60% complete response rate.Hairy Cell Leukemia >60% complete response rate.

-Our own data has been quite convincing.-Our own data has been quite convincing.

Conventional Antibody

s

s

s

s

s

s

s

s

s s

s s

s

s

s

s

s s

s s

s

s

s ss s

Hinges

s ss

VH VH

VLVL

CH1 CH1

CLCL

CH2

CH2

CH3

CH3

s s s

s

VH

VL

Toxin Anti-CD22sFv Anti-CD19sFv

s

s

s

s

VH

VL

s s s

s

VL

VH

DT2219BLT

sFv

The ProcessThe Process

-Splice genes together and then express in -Splice genes together and then express in inducible competent bacteriainducible competent bacteria

-Lyse bacteria, extract and purify protein-Lyse bacteria, extract and purify protein-Test protein against -Test protein against CD22+CD19+CD22+CD19+ Daudi or Raji Daudi or Raji B Lymphoma Cells.B Lymphoma Cells.-Vial drug cGMP-Vial drug cGMP-File pre-IND-File pre-IND

1 2 3 4 5 6 7 8

95 kDa

Bispecific Ligand Directed Bispecific Ligand Directed Toxins (BLT) as a SolutionToxins (BLT) as a Solution

-Powerful, catalytic inhibitors of protein synthesis-Powerful, catalytic inhibitors of protein synthesis

-Mechanism of action very different from chemo. Thus, can be given when -Mechanism of action very different from chemo. Thus, can be given when chemo can no longer be given chemo can no longer be given

-Criteria for a successful BLT:-Criteria for a successful BLT:*Bispecific has greater activity than its monospecific *Bispecific has greater activity than its monospecific counterpartscounterparts*Bispecific is superior to a mixture of the *Bispecific is superior to a mixture of the monospecific counterparts indicating an monospecific counterparts indicating an advantage of advantage of both ligands on the same moleculeboth ligands on the same molecule

-Genetically modifiable-Genetically modifiableGenetic engineering used to increase Genetic engineering used to increase affinity and affinity and

product yield and diminish immunogenicity product yield and diminish immunogenicity

BioAssay - ProliferationBioAssay - Proliferation

% ControlResponse

Therapy of Scid Mice With Systemic Cancer Given DT2219

Inject IV 106 Cells

Measure SURVIVAL

Start TreatmentDay 0 Day 3

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 FACSTo 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

ConclusionsConclusions- 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.