A Phase II Randomized Controlled Trial of Palifosfamide Plus Doxorubicin vs. Doxorubicin In Patients with Soft Tissue Sarcoma (PICASSO) C. F. Verschraegen, S. P. Chawla, M. M. Mita, C. W. Ryan, L. J. Blakely, V. L. Keedy, A. Santoro, J. Y. Buck, R. G. Maki, J. J. Lewis, and PICASSO Study Investigators University of New Mexico Cancer Center, Albuquerque, NM; Sarcoma Oncology Center, Santa Monica, CA; Cancer Therapy & Research Center, San Antonio, TX; Oregon Health & Science University Cancer Institute, Portland, OR; West Clinic, Memphis, TN; Vanderbilt Univ, Nashville, TN; Istituto Clinico Humanitas, Milano, Italy; ZIOPHARM Oncology, Inc, Boston, MA; Memorial Sloan-Kettering Cancer Center, New York, NY

Rationale Palifosfamide-tris, a novel, bi-functional DNA cross- linker, is the stabilized active metabolite of ifosfamide Palifosfamide has broad activity against human sarcoma cell lines in vitro and in human xenografts, including in ifosfamide- and cyclophosphamide-resistant xenograft tumors Mesna administration is not required Chloroacetaldehyde Acrolein IFOS IPM-tris (molecule) Therapeutic metabolite (Palifosfamide-tris) Causes hemorrhagic cystitis Causes encephalopathy

DNA cross linking by Palifosfamide Palifosfamide (7 atom crosslink) (G-X-C sequence) CH 2 NH P-OH O HN-C H 2 -CH 2 5' - X - G - X - C - X - 3' CH 2 3' - X - C - X - G - X - 5' Dong et al. Proc. Natl. Acad. Sci. USA 92: , 1995 Struck et al. Cancer Chemother. Parmacol. 45: The 7-atom crosslink from palifosfamide prevents DNA repair

Preclinical Broad activity in tumor cell lines and human xenografts including osteosarcomas and soft tissue sarcomas Active in −ifosfamide- and cyclophosphamide- resistant cell lines and xenografts −platinum–resistant p388 leukemia/ lymphoma murine model Orally active in p388 leukemia/ lymphoma model and in MX-1 breast cancer xenografts

Synergy with Doxorubicin Xenograft OS31 Palifosfamide (ZIO-201, IPM-tris) + Doxorubicin: tumor size Tumor volume, mm 3 days Palifosfamide + Doxorubicin: Survival Survival probability (%) days

Clinical Activity  Phase I - expected safety profile (ASCO 2006) ─ MTD (Lysine) ~ 400 mg/m 2 iv Days 1,2,3  Phase II single agent, advanced sarcoma (CTOS 2007) ─ Best response: partial response  Phase I palifosfamide/doxorubicin (ASCO 2009) ─ MTD (Tris-mannitol) 150 mg/m 2 iv Days 1,2,3 / 75 mg/m 2 iv Day 1 ─ 2/8 sarcoma responders

Study Design Randomized, multicenter, multinational study in patients diagnosed with unresectable / metastatic soft- tissue sarcoma Arm B: Doxorubicin 75 mg/m 2 Day 1 Arm A: Palifosfamide 150 mg/m 2 Days 1,2,3 Doxorubicin 75 mg/m 2 Day 1 Continuation with Palifosfamide 150 mg/m 2 Days 1,2,3 Stratified randomization Treatment is repeated every 3 weeks x 6 cycles Response evaluations every 6 weeks until progression

Study Design Stratification by –Age: >65 or <65 years –Histologic subtype: Leiomyosarcoma Synovial sarcoma Others

Endpoints Primary –Progression Free Survival (PFS) Secondary –Response (RECIST version 1.0) –Survival –Safety

Statistical Considerations Trial was powered to show the observed HR for PFS significance would be 0.75 An independent DSMB was convened at predetermined points to review data: ─Safety analyses took place following completion of the first cycle of therapy for the 20th subject ─A formal interim PFS efficacy analysis to determine whether to continue, amend, or terminate the study took place subsequent to enrollment of >50% of patients, which coincided with the CTOS presentation ─The pre-specified analysis for PFS in this presentation was for FDA EOP2 meeting.

Major Eligibility Criteria Documentation of sarcoma (excluding alveolar soft-part sarcoma, chondrosarcoma, DFSP, Ewing’s, GIST, Kaposi, mixed mesodermal tumor, osteosarcoma, radiation induced sarcomas, and unresectable low grade liposarcoma) Measurable disease per RECIST Front line or second line Prior treatment with ifosfamide acceptable Doxorubicin naïve Adequate bone marrow, liver, and renal functions

Patients N Palifosfamide+DoxorubicinDoxorubicin Enrolled Treated6633 Eligible Ongoing single agent palifosfamide 1679

Baseline Characteristics of Treated Patients Age and Line of Therapy AgeNPalifosfamide+DoxorubicinDoxorubicin > < Median age6657 years (19-83 years) 57 years (29-80 years) Line of Therapy Front-line4623 Second- line2010

Baseline Characteristics of Treated Patients Histologic Sub-types 5 Liposarcoma 5 Myxofibrosarcoma (MFH) 3 MPNST 2 Spindle Cell Sarcoma 9 Liposarcoma 5 Myxofibrosarcoma (MFH) 2 MPNST 3 Spindle Cell Sarcoma Leiomyosarcoma Synovial Sarcoma Other

Efficacy 62 eligible patients evaluated for PFS with 28 confirmed PFS events  doxorubicin = 18 events  palifosfamide + doxorubicin = 10 events

Primary Endpoint - PFS Hazard ratio = (95% CI: 0.191, 0.951) favoring palifosfamide + doxorubicin (p-value = 0.019) Median PFS: – Doxorubicin = 4.4 months – Palifosfamide + Doxorubicin = 7.8 months

p = HR = palifosfamide + doxorubicin (30) doxorubicin (32) PFS: Patients Receiving/Censored at ≤ 6 Cycles (omitting effect of ongoing or cross-over palifosfamide)

Confirmed Response Rate Palifosfamide+DoxorubicinDoxorubicin N=30N=32 Partial Responders 7 (23%)3 (9%)

Safety Palifosfamide + Doxorubicin (N=33) Doxorubicin (N=33) Grade 3+ Events >10%N%N% Neutropenia Thrombocytopenia SAEs >5% Elevated creatinine3913 Febrile neutropenia1326 Dose reductions824927

Safety Comparison No encephalopathy No hemorrhagic cystitis No mesna No renal Fanconi syndrome Similar bone marrow suppression

Summary PFS: – Hazard ratio is (95% CI: ) favoring palifosfamide + doxorubicin (p-value = 0.019) – Median improvement 3.4 months (4.4 vs 7.8 months) Response Rate: 23% vs 9% Safety: Clinically similar between arms

Conclusions Palifosfamide in combination with doxorubicin is – Well-tolerated – Given in the outpatient setting – Active in soft tissue sarcoma A randomized phase III study, with similar design, is in very late stage of planning