Myrexis Trades 7% Higher After Drug Data Announcment (MYRX)

Myrexis MYRX yesterday announced it presented four posters on its fully synthetic, orally bioavailable heat shock protein 90 (Hsp90) inhibitor, MPC-3100, at the 102nd annual meeting of the American Association for Cancer Research (AACR) in Orlando, Florida. MPC-3100 is currently completing Phase 1 clinical studies in patients with refractory cancers. Myrexis demonstrated that the combination of MPC-3100 with other targeted therapies, including erlotinib and sorafenib, which target the Hsp90 client proteins Epidermal Growth Factor Receptor (EGFR) and B-Raf, respectively, showed greater in vivo anti-tumor activity compared to either agent alone. Biochemical analyses of cancer cells exposed to MPC-3100 + Erlotinib showed that the additive antitumor activity may be attributed to the concentration-dependent decrease in EGFR and other Hsp90 client proteins in this pathway. These preclinical data demonstrate the potential of combining MPC-3100 with other targeted cancer therapies in the clinic. Myrexis also presented a preliminary assessment of its novel L-alanine ester pro-drug of MPC-3100, MPC-0767, which was designed to have improved aqueous solubility when compared to MPC-3100. MPC-0767 demonstrates a >50-fold increase in solubility and efficient conversion into active MPC-3100. It is expected that MPC-0767 will be much easier to formulate into tablets. Animal studies showed that the pro-drug displayed pharmacokinetics comparable to MPC-3100 and equivalent efficacy, inducing significant tumor regressions. "Hsp90 is a well validated cancer target and we've demonstrated strong proof of concept for combination therapy of MPC-3100 with a variety of anti-cancer drugs. We look forward to investigating this further in Phase 2 clinical studies. We are also very encouraged by the preliminary results from our novel pro-drug, MPC-0767 and we will continue to invest in our robust Hsp90 program, from both a clinical and preclinical standpoint," stated Gary Mather, PhD, DVM., Vice President and Head of Development at Myrexis. Myrexis presented additional posters demonstrating the potential use of MPC-3100 against a wide variety of solid and hematological cancers. Biomarker analyses of a number of important Hsp90 client proteins including Her2 and Akt, demonstrated that the anti-tumor activity observed in animals is due to on-target inhibition of Hsp90. Similar analyses of cells isolated from cancer patients treated with MPC-3100 confirmed that Hsp90 function is inhibited in patients at doses that have been well tolerated in the clinic. The ongoing Phase 1 clinical study of MPC-3100 is nearing completion in cancer patients who have exhausted all other therapeutic options. Myrexis is currently enrolling dosing cohort seven of this study and has yet to determine a maximum tolerated dose. The Company expects to advance MPC-3100 to Phase 2 as soon as practicable after completing the Phase 1 study.