02/21/2020 | 12:17am EST

Actinium

Pharmaceuticals,Inc.

Mid-Point Analysis of Pivotal Phase 3 SIERRA Trial Including Materials Presented at 2020 Transplantation & Cellular Therapy Meetings of ASTCT and CIBMTR (TCT)

Targeted Conditioning with Anti-CD45 Iodine (131I) Apamistamab [Iomab-B] leads to High Rates of Allogeneic Transplantation and Successful Engraftment in Older Patients with Active, Relapsed or Refractory AML after Failure of Chemotherapy and Targeted Agents: Preliminary Midpoint Results from the Prospective, Randomized Phase 3 SIERRA Trial

SIERRA: Study of Iomab-B in Elderly Relapsed/Refractory AML

Boglarka Gyurkocza, MD, Rajneesh Nath, MD, Patrick J. Stiff, MD, Edward Agura, MD, Mark Litzow, MD, Ben Tomlinson, MD, Hannah K. Choe, MD, Sunil Abhyankar, MD, Stuart Seropian, MD, George L.

Chen, MD, Parameswaran Hari, MBBS, MD, Zaid S. Al-Kadhimi, MD, James M. Foran, MD, Johnnie Orozco, MD, Koen Van Besien, MD, PhD, Mitchell Sabloff, MD, Partow Kebriaei, MD, Camille Abboud, MD, Moshe Yair Levy, MD, Hillard M Lazarus, MD, Sergio A Giralt, MD, Mark S. Berger, MD, Vijay Reddy, MD, PhD and John M. Pagel, MD, PhD

2

Slides adapted from TCT 2020 oral presentation and include additional data from mid-point analysis of 50% of patients from SIERRA trial

Iodine (131I) apamistamab [Iomab-B] CD45 Targeted Conditioning

Leukemic Bone Marrow

Post-Iomab-B Myeloablated Bone Marrow

Iomab-B

SIERRA Phase 3 Trial Design

Study Design (N=150)

Primary End-point:

Durable Complete Response Rate (dCR): CR/CRp lasting 180 days

Secondary End-point:

1-year Overall Survival

SIERRA Key Eligibility Criteria

Two or more cycles of Venetoclax in combination with Azacitidine or Decitabine (newly added)

Analyzing the Inclusion of Targeted Agents in SIERRA

Therapies Prior to Enrollment into the Trial:

85% patients enrolled had failed 2 regimens (induction/re-induction)

33% had failed targeted therapies Therapies After Enrollment: Control Arm

HCT Rate After Iomab-B vs Std of Care Control

100%

(31/31)

Patients of Percentage

18% (7/38) (7/38)

Standard of Care BMT

6

SIERRA Iomab-B Treatment Schedule

Iomab-B Specific

Standard Transplant Procedure

~7 days

~12 days

Therapy Dose

RIC

HCT

Dosimetry

Iomab-B

Iomab-B

FLU

TBI

(~10-20 mCi)

(24 Gy to liver, mean~600mCi)

30 mg/m2/d

200 cGy

-12 to HCT

-4

-3

-2

-1

0

Immunosuppression

Imaging

RIC: Reduced Intensity Conditioning FLU: Fludarabine

TBI: Total Body Irradiation

HCT: Hematopoietic Cell Transplant

Therapy dose individualized and calculated based on upper limit of 24 Gy liver exposure

SIERRA trial: Demographics highlights of first 75 patients (50% Enrollment)

Phase 3 SIERRA Trial Patient Characteristics (N=75)

Randomized to Iomab-B

Randomized to Conventional Care

(N=37)

(N=38)

Age

65 (55-77)

64 (55-76)

median, (range)

Favorable: 0%

Favorable: 5%

Molecular & Cytogenetic Risk1,3

Intermediate: 34%

Intermediate: 29%

Adverse: 66%

Adverse: 66%

% Bone Marrow Blasts at

Randomization

29% (5-88)2

26% (5-97)

median, (range)

Disease Status at Randomization

Primary Induction Failure: 21 (57)

Primary Induction Failure: 18 (47)

First Early Relapse: 6 (16)

First Early Relapse: 6 (16)

N, (%)

Relapse/Refractory: 6 (16)

Relapse/Refractory: 9 (24)

2nd + Relapse: 3 (8)

2nd + Relapse: 5 (13)

# Prior Regimens at

Randomization

3 (1-5)

3 (1-5)

median, (range)

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Actinium Pharmaceuticals : Mid-Point Analysis of Pivotal Phase 3 SIERRA Trial Including Material Presented at 2020 Transplantation & Cellular...

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