A Los Angeles-area drug company that paid for a year-long option to license the rights to a Calgary firm’s plant-produced insulin has let the option lapse.

MannKind Corp.’s option on SemBioSys Genetics’ insulin product, produced in genetically modified safflower plants, expired Mar. 31 “without action,” SemBioSys said in a release.

MannKind’s decision follows its announcement March 9 that it would buy drug giant Pfizer’s insulin facility at Frankfurt, Germany for US$33 million, including a license to make bulk insulin there for its rapid-acting pulmonary insulin product, Afresa.

Afresa, now in clinical studies, is meant to be an inhalable form of insulin delivered through a small palm-sized device. MannKind’s option, if exercised, would have made Afresa the “primary use” of SemBioSys’ safflower-based product.

The decision by MannKind, which paid US$2.5 million for its option with SemBioSys, now leaves the Calgary company “free to execute agreements relating to its insulin program with other parties,” SemBioSys said.

But the news also comes just as SemBioSys reported results from the Phase I/II trials of its safflower-based recombinant human insulin in human volunteers. In the tests, SemBioSys’ SBS-1000 product was “shown to be bioequivalent to Eli Lilly’s Humulin,” a widely-used human insulin.