Celsion had a liposomal based drug that relied on being 'heat activated' by a device placed over the target organ(the liver) which was supposed to cause the liposome enclosed drug to be released at the site where it was needed. The technology was a bit far fetched to begin with(in my opinion) and the trial failed. They did not get the improved delivery and targeting they were shooting for.
The relevant comparison to make for 398 is with the Abraxane. Both Abraxane and 398 are repackaging of old drugs with known therapeutic benefits---Taxol in the former case and Irinotecan in the latter---and the take home message from the highly successful Abraxane trial was that improved delivery results in improved efficacy. The early 398 results(Phase II, done by Pharma Engine in Korea under the name of PEP02) indicated the same trend: the repackaging of irinotecan in 398 resulted in higher drug deposition at the site of the tumor and therefore a better efficacy profile.
Phase III on 398 out later this year, but if anything the odds of it's success have improved, not worsened.
I agree with you. the only similarity is that MM-398 and Thermodox were both targeting difficult indications with encapsulated pre existing therapies (Celsion LTSL Doxil) & MACK (encapsulated irinotecan). Personally I'm in MACK for MM-121, MM-111, and MM-141 but I understand the market is waiting on MM-398 this spring. The compounds working on the "Grand central Station" of tumor signaling, ErbB3