CytRx (CYTR) Announces Statistically Significant Data from Aldoxorubicin Phase 3 in r/r STS

November 29, 2016 7:03 AM EST
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CytRx Corporation (Nasdaq: CYTR) announced positive updated results from its pivotal Phase 3 clinical trial evaluating aldoxorubicin compared to investigator's choice in patients with relapsed or refractory soft tissue sarcomas (STS). The study, which enrolled 433 patients, demonstrated a statistically significant improvement in progression-free survival (PFS) between aldoxorubicin and investigator's choice therapy in 246 patients with leiomyosarcoma and liposarcoma, (p=0.007). The hazard ratio (HR) was 0.62 (95% CI 0.44-0.88), representing a 38% reduction in the risk of tumor progression for patients receiving aldoxorubicin versus investigator's choice. Leiomyosarcoma and liposarcoma are the two most common types of STS and accounted for 57% of the patients enrolled in the trial.

Aldoxorubicin demonstrated a statistically significant improvement in PFS over investigator's choice in 312 patients treated in North America (p=0.028; HR=0.71, 95% CI 0.53-0.97). Notably, aldoxorubicin performed better than investigator's choice for the entire study population and narrowly missed statistical significance (p=0.12; HR=0.81, 95% CI 0.64-1.06). All responses were determined by an independent, blinded central lab assessment of scans.

"This data represents a major step forward for STS, a rare, highly complex and very difficult-to-treat group of cancers," commented Sant Chawla, M.D., F.R.A.C.P., Director of the Sarcoma Oncology Center in Santa Monica, California, and Principal Investigator for the Phase 3 trial. "These results are important because they demonstrate that treatment with aldoxorubicin can extend the time to progression in a clinically meaningful way. The trial design used was more stringent than any prior clinical trial in STS as it compared aldoxorubicin to real world alternatives. The control arm allowed trial investigators to select any one of the five most widely used treatments best suited for their patients' specific type of STS. Unlike other clinical trials for relapsed or refractory STS which used either dacarbazine or placebo as the control, this study was biased in favor of choosing the best therapy for the patients, a truly unique study design."

CytRx plans to submit the results of this clinical trial for presentation at an upcoming major scientific meeting.

In the entire study population, aldoxorubicin achieved a statistically significant improvement in the disease control rate (DCR; defined as objective response rate (ORR) plus stable disease for at least 4 months) of 29.4% versus 20.5% for the patients treated with investigator's choice (p=0.030). In North American patients, the benefit was even more pronounced with aldoxorubicin-treated patients exhibiting a DCR of 32.9%, compared to 19.2% for patients treated with investigator's choice (p=0.007), an overall improvement of 71%. ORR in North American patients also favored aldoxorubicin over investigator's choice, 8.7% versus 3.3% (p=0.058). Of note, no objective responses were observed in patients treated with Votrient® (pazopanib). Patients continue to be followed for overall survival (OS), a secondary endpoint, and CytRx expects the OS data to be available in 2017.

PFS, DCR and ORR data are summarized in the following table:

Phase 3 Aldoxorubicin Efficacy Results

N

Aldoxorubicin

Investigator's Choice

P Value

All patients with Leiomyosarcoma and Liposarcoma (PFS)

246

HR = 0.62 (95% CI 0.44-0.88)

0.007

North American1 patients (PFS)

312

HR = 0.71 (95% CI 0.53-0.97)

0.028

Disease Control Rate (DCR)2

32.9%

19.2%

0.007

Objective Response Rate (ORR)

8.7%

3.3%

0.058

All patients (PFS)

433

HR = 0.81 (95% CI 0.64-1.06)

0.120

Disease Control Rate (DCR)2

29.4%

20.5%

0.030

1Per trial statistical analysis plan, North America is defined as United States, Canada and Australia and comprises 72% of total trial patients

2DCR=ORR + stable disease for ≥4 months

Pre-specified analyses were based on sarcoma histopathology and geography. The geographic analysis includes patients from North America (defined as the United States, Canada and Australia, per the trial statistical analysis plan). The 312 patients treated in North America comprise 72% of the total trial population, including 296 patients from the United States, 8 patients from Canada and 8 patients from Australia. The 246 patients with leiomyosarcoma or liposarcoma comprise 57% of the total trial population.

Aldoxorubicin did not cause clinically significant cardiac, renal, or hepatic toxicities. For the global trial population, the most commonly reported adverse events were neutropenia and anemia consistent with prior clinical trials with aldoxorubicin. Grade 3 or higher hypertension occurred in patients receiving Votrient® (pazopanib). Grade 3 or higher adverse events were manageable with supportive care and occurred at a rate of 61% for patients receiving aldoxorubicin and 46% in patients treated with investigator's choice. Importantly, treatment-emergent adverse events leading to discontinuation occurred in 4.2% of patients treated with aldoxorubicin, compared to 6.3% for patients receiving investigator's choice. Serious adverse events, primarily febrile neutropenia that resolved and rarely led to treatment termination occurred more frequently in patients administered aldoxorubicin. Treatment-related deaths occurred in one aldoxorubicin-treated patient and in no patients receiving investigators' choice drugs.

Based on these results, CytRx expects to submit a New Drug Application (NDA) with the U.S. Food and Drug Administration (FDA) for aldoxorubicin as a treatment for patients with relapsed or refractory STS in 2017.

"These results show that globally leiomyosarcoma and liposarcoma patients treated with aldoxorubicin exhibited significantly longer PFS than patients treated with both FDA-approved and commonly used therapies in the second-line setting," said Daniel Levitt, M.D., Ph.D., EVP and Chief Medical Officer of CytRx. "We are also very encouraged by the statistically significant improvements observed in North American STS patients treated with aldoxorubicin who exhibited both longer PFS and superior response rates."

"We are deeply grateful for the support and commitment of the sarcoma investigators, along with the patients and families who took part in or contributed to this Phase 3 trial," stated Steven A. Kriegsman, CytRx's Chairman and Chief Executive Officer. "We look forward to sharing the data from these key patient populations with the FDA to support an NDA for aldoxorubicin as a second-line treatment for patients suffering with soft tissue sarcomas."

Conference Call and Webcast

CytRx management will be hosting a conference call and webcast today beginning at 8:30 a.m. Eastern Time / 5:30 a.m. Pacific Time to discuss the results of the Phase 3 trial. To access the conference call, dial 844-358-6753 (U.S. and Canada) or 216-562-0397 (international callers) and enter the conference ID number: 27115631. A webcast will be available in the investor relations section of the company's website, www.cytrx.com. A replay of the call and webcast will begin approximately two hours after the live call has ended. To access the replay, dial 855-859-2056 (U.S. and Canada) or 404-537-3406 (international callers) and enter the conference ID number: 27115631.



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