CytRx Corporation, a biopharmaceutical research and development company engaged in the development of high-value human therapeutics, announced that its proprietary drug candidate INNO-206 dramatically inhibited tumour growth in an experimental animal model of small cell lung cancer (SCLC). The results of the trial have been released in electronic form and accepted for publication in the peer-reviewed journal Investigational New Drugs.

CytRx's INNO-206 is a pro-drug derivative of the commonly prescribed chemotherapeutic agent doxorubicin. INNO-206 is designed to reduce adverse events by controlling drug release and preferentially targeting tumours. In a phase-1 clinical trial, INNO-206 was administered in doses at up to six times the standard dosing of doxorubicin without an increase in observed side effects over those historically seen with doxorubicin. In the phase-1 clinical trial of 35 patients with various cancers treated with INNO-206, three patients showed a partial tumour reduction and 20 patients showed stable disease over the course of the trial. All three of the partial responses occurred at the higher dose ranges of the dose-ranging safety study.

CytRx president and CEO Steven A Kriegsman stated, "We hold the exclusive worldwide rights to INNO-206, which has demonstrated statistically significant efficacy in animal models of multiple cancer types. INNO-206 epitomizes our corporate strategy of minimizing development risk by focusing on drug candidates that have been tested in humans with very fundamental mechanisms of action that make them potentially efficacious in multiple oncology indications. The ability to inhibit SCLC tumour growth in an animal model is gratifying given the fact that this cancer is particularly devastating. In light of this compelling animal data in SCLC, and previously announced positive data showing INNO-206's potential to treat breast, pancreatic and ovarian cancer, we are designing potential phase-II clinical trials for one or more of those deadly diseases, and expect to announce our plans in the fourth quarter of 2009."

INNO-206 inventor Dr Felix Kratz, Department of Medical Oncology, Clinical Research, at the Tumour Biology Center in Freiburg, Germany, directed the animal study in which 10 million human H209 SCLC tumour cells from cell culture were transplanted under the skin of 32 mice, all lacking a normal immune system that would otherwise reject these cells. When the tumours had grown to a palpable size 20 days later, the experimental animals were randomly separated into four treatment groups of eight each. Two groups were treated with two cycles of weekly 8 mg/kg intravenous injections of either doxorubicin or CytRx's INNO-206. Although doxorubicin doses above eight mg/kg were not tolerable and resulted in animal deaths, INNO-206's lower toxicity allowed the third animal group to be treated more aggressively, with three weekly cycles of 24 mg/kg INNO-206 injections. The fourth group received intravenous injections lacking either drug and served as a control. Tumour growth was monitored continuously throughout the remainder of the 44-day experiment.

Neither doxorubicin nor INNO-206 at two weekly cycles of 8 mg/kg intravenous dosing produced evidence of significant anti-tumour effect, with relative-tumour volumes increasing approximately 20-fold or 16-fold, respectively, 24 days after initiation of therapy, which was comparable to the control. However, the group treated with three weekly cycles of 24 mg/kg intravenous INNO-206, because of its improved tolerability compared to doxorubicin, produced a statistically significant (p<0.05) anti-tumour effect with relative tumour volumes increasing only by a factor of approximately 3.5 at the end of the experiment. In addition to the remarkably improved efficacy of INNO-206 compared to doxorubicin, its toxicity based on body weight loss following three weekly cycles of 24 mg/kg was comparable to that seen with only two weekly cycles of doxorubicin at 8 mg/kg based on body weight loss.

"We were not surprised that doxorubicin did not significantly inhibit tumor growth in this animal model as this broadly prescribed chemotherapeutic agent has not proven effective as an SCLC treatment unless used as part of a multi-drug cocktail," stated Joseph Rubinfeld, co-founder of Amgen, CytRx chief scientific advisor and world-renown oncologist. "By contrast, higher doses of the more tolerable INNO-206 showed dramatic and statistically significant inhibition of tumour growth even as a single agent in this animal model, apparently because its pro-drug structure allowed for the accumulation of higher levels of the drug specifically targeting the tumour."

INNO-206 is a prodrug of the commonly prescribed chemotherapeutic doxorubicin and was designed to reduce adverse events by controlling release and preferentially targeting the tumour.

CytRx Corporation is a biopharmaceutical research and development company engaged in the development of high-value human therapeutics.