US-based biopharmaceutical research and development firm CytRx, has started a global Phase IIb clinical trial assessing aldoxorubicin compared to topotecan in patients with extensive-stage small cell lung cancer (SCLC,) who have relapsed or were refractory to prior chemotherapy.

Aldoxorubicin is the company’s modified version of the chemotherapeutic agent doxorubicin.

The company has also received orphan drug designation to treat SCLC from the US Food and Drug Administration (FDA).

The open-label trial is expected to enrol around 132 patients with extensive-stage SCLC who have relapsed or were refractory to prior chemotherapy.

"Aldoxorubicin is the company’s modified version of the chemotherapeutic agent doxorubicin."

In the trial, patients will receive either aldoxorubicin or topotecan and its primary endpoint is progression-free survival (PFS) and the secondary endpoints are overall survival (OS), overall response rates (partial and complete) and the safety of aldoxorubicin compared to topotecan in these patients.

The company intends to complete enrolment of the trial in 2015 and PFS data are expected by mid-2016.

The trial will be conducted at about 40 clinical trial sites in the US, Spain, Italy and Hungary.

CytRx executive vice-president and chief medical officer Dr Daniel Levitt said: "The significant toxicities associated with topotecan, the only approved chemotherapy for the treatment of second-line SCLC, prevent many patients from even finishing one course of treatment, translating to poor response and overall survival rates.

"Based on its mechanism of action, data observed in a broad range of tumor types, and compelling Phase 1 pharmacokinetic data in metastatic, treatment relapsed or refractory solid tumors, aldoxorubicin may offer patients an improved tolerability profile together with significant improvements in clinically meaningful efficacy measures in this indication.

"Our previous data in relapsed or refractory solid tumor patients indicates that the dose of aldoxorubicin being administered to these patients is well tolerated and without any treatment-limiting side effects.

"Up to 21 cycles (4.8 grams/m2) have been given to one patient with small cell lung cancer with minimal side effects and good anti-tumor activity."

Last year, the company reported results from its Phase Ib clinical trial of aldoxorubicin in patients with metastatic solid tumors who have either relapsed or not responded to treatment with standard therapies.

The trial showed that treatment with aldoxorubicin extended to 21 cycles in a patient with small cell lung cancer as well as to more than 10 cycles in several other patients.

CytRx CEO Steven Kriegsman said: "Initiation of this global clinical trial builds on our substantial experience evaluating aldoxorubicin in soft tissue sarcomas (STS), glioblastoma multiforme and Karposi’s sarcoma, and reflects our strategy to leverage the broad potential of aldoxorubicin into a variety of solid tumor and hematological indications.

"We are particularly interested in the potential of aldoxorubin in small cell lung cancer, as this tumor type typically is more sensitive to chemotherapy than STS."