Sunesis Pharmaceuticals Presents Voreloxin Clinical Data at the American Society of Clinical Oncology 2009 Annual Meeting

 -- In Schedule A (72 mg/m2 of voreloxin weekly for three weeks), 29

      patients have been enrolled and treated.

      -- 20 of 29 patients (69 percent) were 70 years of age or older.

      -- The majority of patients had intermediate or unfavorable

          cytogenetics.

      -- 12 patients achieved a complete remission (CR) or complete

          remission without full platelet recovery (CRp) for an overall

          remission rate of 41 percent.

      -- Eight of 12 responders received one consolidation cycle of

          voreloxin and no responders received a second consolidation cycle.

      -- Grade 3 or higher non-hematologic adverse events occurring in more

          than 10 percent of patients include mucosal inflammation,

          infections and fatigue.

      -- The 30-day all-cause mortality rate was 17 percent, which compares

          favorably to standard induction chemotherapy. Infection was the

          most common cause of early mortality.

 -- In Schedule B (72 mg/m2 of voreloxin dosed weekly for two weeks), 35

      patients have been enrolled and treated.

      -- 27 of 35 patients (77 percent) were 70 years of age or older.

      -- The majority of patients had intermediate or unfavorable

          cytogenetics.

      -- Data from these patients suggest that Schedule B is better

          tolerated. The incidence of Grade 3 or higher mucosal inflammation

          has been reduced by more than 50 percent relative to Schedule A.

          The 30-day all-cause mortality has also been reduced to 9 percent.

      -- Anti-leukemic activity has been maintained. 10 patients achieved a

          CR or CRp for an overall remission rate of 29 percent.

      -- The number of responders receiving either one or two consolidation

          cycles increased. All 10 responders received one consolidation

          cycle of voreloxin and seven of 10 responders received a second

          consolidation cycle. While still too early to calculate, this may

          contribute to an improved median duration of remission in Schedule

          B compared to Schedule A.

 -- In Schedule C (72 mg/m2 of voreloxin dosed on days one and four), 28

      patients have been enrolled and treated.

      -- It is still too early for a complete remission evaluation, but

          four CRs and two CRps of 19 evaluable patients have been achieved

          to date, while nine patients are too early to evaluate.

      -- As with Schedule B, early data from patients suggest that Schedule

          C is better tolerated than Schedule A and activity has also been

          maintained. The 30-day all-cause mortality is currently nine

          percent (two of 23).

      -- Based on the current safety profile of 72 mg/m2 of voreloxin in

          Schedule C as well as the ongoing Phase 1b/2 experience of 90

          mg/m2 of voreloxin dosed on days one and four in combination with

          cytarabine, an additional cohort of approximately 20 patients will

          be enrolled at 90 mg/m2 in Schedule C.

 -- The median duration of remission and the median overall survival have

      not yet been reached in any schedule.

      -- In Schedule A, five of 12 responders remain in remission for over

          seven months while four have relapsed and three have withdrawn

          from remission follow-up.

      -- In Schedule B, nine of 10 responders remain in remission to date.

      -- More than half of all patients in Schedules A and B have survived

          more than six months.

"Voreloxin's anti-leukemic activity in this previously untreated, older adult patient population with AML is promising," said Robert K. Stuart, M.D., Professor of Medicine, Division of Hematology/Oncology, Department of Medicine, Medical University of South Carolina, and an investigator in the study. "I am encouraged by the complete remissions observed thus far in patients who are unlikely to benefit from standard induction therapy. Additionally, the convenience of a ten minute injection is an added benefit for both staff and patients."

 -- The Phase 1 dose escalation in both the CIV and Bolus Schedules has

      been completed with a maximum tolerated dose/recommended Phase 2 dose

      of 80 mg/m2 and 90 mg/m2, respectively.

      -- Between both schedules, 57 relapsed or refractory patients have

          been enrolled and treated in the dose escalation.

      -- In the Phase 1 portions of this study, infection related

          toxicities were the most common Grade 3 or higher adverse events.

          The overall incidence of Grade 3 or higher mucosal inflammation

          was 11 percent when patients from both the CIV and Bolus Schedules

          are combined.

      -- In the dose escalation, nine of 39 patients (23 percent) in the

          CIV Schedule and four of 18 patients (22 percent) in the Bolus

          Schedule achieved a CR or CRp. Responders included first relapse,

          second relapse, primary refractory and relapsed/refractory

          patients.

      -- In the CIV Schedule dose escalation, six of nine responders to

          date have had a remission of at least eight months and a third of

          responders went on to receive a bone marrow transplant.

      -- It is too early to evaluate remission duration in the Bolus

          Schedule dose escalation.

      -- Across both the CIV and Bolus Schedules, a total of 14 patients

          with primary refractory AML were enrolled and treated with a

          voreloxin dose of 80 mg/m2 or higher. Five of 14 of these patients

          achieved a CR or CRp for an overall CR or CRp rate of 36 percent,

          which compares favorably relative to expected remission rates in

          this AML population of approximately 10 to 15 percent.

 -- In Phase 2, 16 AML patients in first relapse were enrolled in the CIV

      Schedule.

      -- Infection related toxicities were the most common Grade 3 or

          higher adverse events and no Grade 3 or higher mucosal

          inflammation was observed.

      -- Six CRs and one CRp were achieved for an overall CR or CRp rate of

          44 percent, which compares favorably relative to the expected

          single agent cytarabine remission rate of approximately 20

          percent. Five first relapse AML patients were enrolled in the dose

          escalation in the CIV Schedule at a dose of 80 mg/m2 or higher, of

          whom none achieved a CR or CRp.

      -- Three of seven responders had an initial remission, or CR1, of

          less than 12 months, and to date, five of seven responders remain

          in remission.

      -- In the Bolus Schedule, both first relapse and primary refractory

          patients are currently being enrolled in Phase 2.

"Voreloxin has demonstrated anti-leukemic activity when administered in combination with both continuous infusion and bolus cytarabine," said Jeffrey Lancet, M.D, Assistant Professor and Section Chief of the Leukemia Program, Division of Hematologic Malignancies at the H. Lee Moffitt Cancer Center & Research Institute, and an investigator in this voreloxin/cytarabine combination study in AML. "Voreloxin has induced remissions in several difficult to treat AML patient populations, including relapsed, primary refractory and relapsed/refractory AML patients. I look forward to the final results of this study and the continued clinical investigation of voreloxin."

 -- Three dose cohorts of voreloxin have been studied, 48 mg/m2 given

      every three weeks (N=65), 60 mg/m2 given every four weeks (N=37) and

      75 mg/m2 given every four weeks (N=35). Enrollment completed in

      December of 2008. 16 patients in the 60 mg/m2 and 75 mg/m2 cohorts

      remain on study.

 -- Data from this trial show encouraging durable anti-tumor activity

      across all three dose cohorts. The overall response rate (ORR), as

      measured by GOG RECIST criteria, was eleven percent for each of the

      three dosing cohorts: two complete responses (CR) and five partial

      responses (PR) in cohort A (48 mg/m2 q3 weeks), two CRs and two PRs in

      cohort B (60 mg/m2 q4 weeks) and four PRs in cohort C (75 mg/m2 q4

      weeks).

 -- 74 patients (52 percent) experienced disease control, defined as an

      objective response or stable disease for 12 weeks or more.

 -- The median progression free survival (PFS) for cohort A was 82 days.

      The preliminary median PFS for cohorts B and C is 84 days and 109

      days, respectively. There was a significant difference in PFS among

      the 3 dose cohorts (p = 0.019). PFS was significantly longer in the 60

      and 75 mg/m2 cohorts vs. 48 mg/m2, suggesting a benefit to higher

      voreloxin doses.

 -- Four PRs were achieved in the 44 women who were Doxil(R) failures for

      an ORR of nine percent and 28 (64 percent) achieved disease control.

 -- The preliminary median PFS in these Doxil(R) failure patients is 90

      days. PFS was not statistically different from those who had not

      failed Doxil(R).

 -- Overall, the adverse event profile was similar across cohorts and

      voreloxin was generally well-tolerated. Grade 3 or higher adverse

      events occurring in more than 10 percent of patients include

      neutropenia, febrile neutropenia, and anemia.

 -- The incidence of febrile neutropenia was increased in cohort C (75

      mg/m2 q4 weeks), and was clinically manageable and within the range of

      other commonly used and approved agents in ovarian cancer.

"Voreloxin continues to demonstrate promising clinical activity in a vastly underserved patient population," said Robert P. Edwards, M.D., Professor of Obstetrics, Gynecology, and Reproductive Sciences and Vice Chair of the Division of Gynecologic Oncology at the University of Pittsburgh, and an investigator for the Phase 2 clinical trial. "I am encouraged by the preliminary data, including the activity in patients that are resistant or refractory to both platinum-based chemotherapy and Doxil(R)."

 Investor Contact:                         Media Contact:

 Sunesis Pharmaceuticals, Inc.             Sunesis Pharmaceuticals, Inc.

 Eric Bjerkholt                            Dan Weinseimer

 650-266-3717                              650-266-3739

Source: Sunesis Pharmaceuticals, Inc.