Iterum bags $65M for phase 3 trial of ex-Pfizer antibiotic

Iterum has completed a $65 million (€58 million) series B to equip it to take its antibiotic sulopenem through phase 3. The financing moves the total raised by the Irish biopharma company since it emerged last year armed with an antibiotic developed by Pfizer past the $100 million mark.

Arix Bioscience led the round with support from fellow new investors such as Advent Life Sciences and all the financiers who backed the $40 million series A last year, a list that includes Frazier Healthcare Partners, Canaan Partners and Sofinnova Ventures. The investors put together the big back-to-back rounds to equip Iterum to take an antibiotic it picked up from Pfizer through a phase 3 trial in patients with uncomplicated urinary tract infections (uUTI).

Iterum plans to start the phase 3 of in the first half of next year and go on to file for approval from the FDA by the end of 2019. That timeline represents a slight slip from Iterum’s earlier plans, which had it moving into phase 3 by the end of this year.

In parallel to preparations for the uUTI trial, Iterum will work toward setting up a broader phase 3 program. Iterum sees sulopenem as an oral or intravenous treatment for gram-negative, multidrug resistant infections, notably the Enterobacteriaceae mutants of Escherichia coli and Klebsiella pneumoniae. The presence of these pathogens in complicated infections of the urinary tract and intra-abdominal region mean these indications join uUTI on Iterum’s initial hit list.

Pfizer first published details of its synthesis of sulopenem in the early 1990s and went on to put it through a phase 2 trial. Data presented in 2010 linked two regimens of sulopenem—both of which started with an intravenous formulation before switching to oral dosing—to cure rates of 90% and 88% in patients with community-acquired pneumonia requiring hospitalization. Subjects who took ceftriaxone followed by an amoxicillin-clavulanate suspension had a cure rate of 63%.

That meant the trial failed to show a statistically-significant difference between the sulopenem and control arms, but the size of the study made it hard draw concrete conclusions. Pfizer enrolled 33 patients in the trial, fewer than it initially planned, and 10 discontinued. The dropouts came from the control and sulopenem arms of the trial. The control arm had more adverse event-related discontinuations and as many serious adverse events as the sulopenem arms combined.

Despite the researchers behind the study stating sulopenem warranted further investigation, the drug slipped down the pecking order at Pfizer and largely vanished from view until Iterum intervened. Pfizer offloaded the drug late in 2015 in exchange for a stake in Iterum, an upfront cash payment and a chance to receive additional equity, milestones and royalties down the line.

The deal came about after Corey Fishman and Michael Dunne, M.D. identified sulopenem as their route back into drug development. Fishman and Dunne were part of the management team at Durata Therapeutics that won approval for the antibiotic Dalvance before attracting a $675 million buyout bid from Actavis. Durata, like Iterum, picked up its antibiotic from Pfizer and secured investment from Canaan Partners, Domain Associates, New Leaf Venture Partners and Sofinnova Ventures.

This time around Fishman and Dunne have also leaned heavily on Arix, a British investment group that was set up around the time they founded Iterum. Arix led the series B, making Iterum its first big publicly-disclosed investment since it completed its £100 million IPO earlier this year.