A group from the Seoul National University and the Marine natural products laboratory in Seoul lead by Shin and Ohhave been busy isolating some interesting natural products from a Coscinoderma sponge which you can read about here.

Coscinolactam A containing the unusual enol sulphonate group demonstrates moderate cytotoxicity comparable to that of doxorubin.

whereas the novel suvanine salt showed significant antibacterial activity:

In addition to these and other compounds the irciniasulphonic acids 1 & the sodium salt 2 were isolated:

Unfortunately these compounds were  as antibacterials and did not show any cytotoxicity.

However the compounds described in this paper are interesting natural products, relatively easy to synthesise and who knows? Perhaps a lead would emerge from such a study.