hMaxi-K gene transfer in males with erectile dysfunction: Results of the first human trial

Arnold Melman, Natan Bar-Chama, Andrew McCullough, Kelvin Davies, George Christ

Research output: Contribution to journalArticlepeer-review

97 Scopus citations


Eleven patients with moderate to severe erectile dysfunction (ED) were given a single-dose corpus cavernosum injection of hMaxi-K, a "naked" DNA plasmid carrying the human cDNA encoding hSlo (for human slow-poke), the gene for the α, or pore-forming, subunit of the human smooth muscle Maxi-K channel. Three patients each were given 500,1000, and 5000 μg, and two patients were given 7500 μg, of hMaxi-K and monitored for 24 weeks. The primary objectives of this phase I study were safety and tolerability of escalating hMaxi-K doses as assessed by clinical evaluations and laboratory tests. Secondary efficacy objectives were measured primarily by use of the International Index of Erectile Function (IIEF) scale. Patient responses were validated by partner responses. There were no serious adverse events and no dose-related adverse events attributed to gene transfer for any patient at any dose or study visit. No clinically significant changes from baseline were seen in physical evaluations (general and genitourinary), hematology, chemistry, and hormone analyses, or in cardiac events evaluated by repeated electrocardiograms. Importantly, no plasmid was detected in the semen of patients at any time after the injections. Patients given tlie two highest doses of hMaxi-K had apparent sustained improvements in erectile function (EF) as indicated by improved HEF-EF domain scores over the length of the study. One patient given 5000 μg and one given 7500 μg reported EF category improvements that were highly clinically significant and were also maintained through the 24 weeks of study. Efficacy conclusions cannot be drawn from results of a phase I trial with no control group. However, the promising primary safety outcomes of the study and preliminary indications of effectiveness provide evidence that hMaxi-K gene transfer is a viable approach to the treatment of ED and that further studies investigating the efficacy of hMaxi-K in patients with ED should be performed.

Original languageEnglish (US)
Pages (from-to)1165-1176
Number of pages12
JournalHuman Gene Therapy
Issue number12
StatePublished - Dec 2006

ASJC Scopus subject areas

  • Molecular Medicine
  • Molecular Biology
  • Genetics


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