CytRx (CYTR) Reports Positive Secondary Endpoint Results from Aldoxorubicin Combo Phase 2b

January 22, 2015 9:03 AM EST
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CytRx (NASDAQ: CYTR) announced encouraging overall survival (OS) results, the secondary endpoint, from its completed multicenter, randomized, open-label global Phase 2b clinical trial investigating the efficacy and safety of aldoxorubicin compared with doxorubicin as first-line therapy in subjects with metastatic, locally advanced or unresectable soft tissue sarcomas (STS).

The OS results in 123 patients demonstrated that aldoxorubicin-treated patients demonstrated a 27 percent reduction in the risk of death compared to patients treated with doxorubicin (HR 0.73: 95% confidence interval 0.44-1.20), the current standard-of-care in this indication. In addition, aldoxorubicin-treated patients demonstrated a 41% likelihood of surviving more than 2 years, a 2-fold increase, compared to a 20% probability for doxorubicin-treated patients. Median overall survival was 16.0 months (95% confidence interval 13.1-not reached) for aldoxorubicin-treated patients versus 14.4 months (95% confidence interval 8.7-20.9) for doxorubicin treated patients (p=0.21). For treatment-naive patients, representing 90% of the patients in the clinical trial, median overall survival was 16.0 months (95% confidence interval 13.1-not reached) for aldoxorubicin-treated patients versus 14.0 months (95% confidence interval 8.7-20.1) for doxorubicin treated patients (p=0.14).

These final OS results were assessed as part of a prospectively planned secondary endpoint analysis and were not powered to demonstrate statistically significant overall survival. The positive trend could be significantly improved, now that the FDA has permitted CytRx to dose aldoxorubicin in all trials until tumor progression. Previously reported primary endpoint results, as determined by both the trial investigators and by blinded central radiology review, found that subjects treated with aldoxorubicin demonstrated highly statistically significantly better clinical outcomes than subjects that received standard doxorubicin therapy for their soft tissue sarcomas. In scans read by trial investigators, progression-free survival (PFS) results demonstrated that treatment with aldoxorubicin increased median PFS approximately 79% to 8.4 months, compared to 4.7 months with doxorubicin, meeting the study's primary endpoint (HR=0.419; p=0.0007). In blinded central radiology review, PFS results demonstrated that treatment with aldoxorubicin increased median PFS approximately 104% to 5.7 months, compared to 2.8 months with doxorubicin, also meeting the study's primary endpoint (HR=0.584; p=0.024).

"The past few decades have brought us very few treatment advances in soft tissue sarcoma," said Sant P. Chawla, M.D., FRACP, Director of the Sarcoma Oncology Center and Principal Investigator of the global Phase 2b clinical trial. "These results indicate that aldoxorubicin could improve clinical outcomes in patients compared to doxorubicin therapy, the current standard-of-care in this indication. We have seen promising improvements in progression-free survival, tumor shrinkage, overall response rates, and now overall survival in patients with a wide variety of soft tissue sarcomas. What is especially meaningful is that after only 6 cycles of aldoxorubicin treatment, the likelihood of survival at 2 years or more is twice that of patients administered doxorubicin. While no drug or combination to date has shown statistically significant increases in median overall survival versus doxorubicin, the improvement in long term outcome for aldoxorubicin-treated patients is an important step forward in offering potential new hope for soft tissue sarcoma patients."

"We are very pleased by these secondary endpoint results, particularly the two-fold increase in the likelihood of survival of more than 2 years, as survival benefit has remained an elusive goal in the treatment of soft tissue sarcoma," said Steven A. Kriegsman, Chairman and CEO of CytRx. "We look forward to the potential of translating these promising results in our pivotal global Phase 3 clinical trial, and to understanding the potential for added benefit when dosing aldoxorubicin until progression, which was not part of the Phase 2b study design."

Other previously reported secondary endpoint results included PFS at 6 months and both complete and partial objective response rates (ORR). In scans read by trial investigators, PFS at 6 months results demonstrated that treatment with aldoxorubicin increased median PFS at 6 months by approximately 86%, compared to doxorubicin, meeting this secondary primary endpoint (p=0.002). In blinded central radiology review, PFS at 6 months results demonstrated that treatment with aldoxorubicin increased median PFS at 6 months by approximately 100%, compared to doxorubicin, meeting this additional secondary endpoint (p=0.02). The ORR as determined by the investigators was 21.7% for aldoxorubicin subjects (2.4% complete response and 19.3% partial response) versus 5.0% for doxorubicin subjects (0% complete response and 5.0% partial response). As assessed by blinded central lab review, 23.8% of aldoxorubicin subjects had a partial response while 0.0% of doxorubicin subjects exhibited any objective response. In addition, a higher percentage of aldoxorubicin-treated subjects demonstrated tumor shrinkage compared to patients treated with doxorubicin, regardless of whether the scans were evaluated by investigators (65.4% vs. 41.2%) or by blinded reviewers (60.8% vs. 39.4%).

Adverse events, as previously reported, were consistent with known doxorubicin toxicities. The majority of adverse events resolved prior to the following cycle with no treatment discontinuation. Aldoxorubicin-treated subjects experienced a higher percentage of Grade 3 or 4 treatment emergent adverse events (TEAEs) of neutropenia (40% vs. 20%), mucositis (11% vs. 3%) and nausea/vomiting (7% vs. 0%). All TEAEs resolved and were not treatment limiting. No clinically significant cardiotoxicity was seen with aldoxorubicin while approximately 10% of doxorubicin patients had clinically significant cardiotoxicity. Most importantly, there was no clinically significant reduction in cardiac function in the aldoxorubicin patients despite receiving 3.5 times the standard dose of doxorubicin.



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