On Heels of $100M Financing, Annexon Bio Aims to Tack On More Via IPO

Xconomy San Francisco — 

The same week Annexon Biosciences announced it had raised $100 million in private financing to advance its research of antibody drugs to treat neurodegeneration, the company filed paperwork with regulators indicating its intention to tap the public markets, too.

The South San Francisco-based company has two clinical-stage product candidates, both of which are designed to inhibit a protein known as Cq1, which plays a key role in an immune system called the classical complement cascade. Its most advanced, ANX005, is being studied as a potential treatment for the autoimmune disease Guillain-Barre syndrome (GBS), a disorder called warm autoimmune hemolytic anemia in which the immune system prematurely attacks the body’s own red blood cells, and in two neurodegenerative conditions, Huntington’s disease and amyotrophic lateral sclerosis.

According to its prospectus, Annexon anticipates initial data from Phase 2 trials in all those indications next year, except for the GBS study, which is expected to yield Phase 2/3 data in 2023.

Annexon is also in the clinic with an antibody fragment, ANX007, evaluating its potential neuroprotective benefits for patients with an advanced form of “dry” age-related macular degeneration called geographic atrophy. A subcutaneous drug candidate, ANX009, is in preclinical development as a potential treatment for systemic autoimmune diseases.

The company’s IPO is intended to help pay for those studies as well as advance its earlier-stage and next-generation drug candidates. The company set a preliminary target of $100 million for the offering and has applied to list on the Nasdaq exchange under the stock symbol “ANNX.”

Discoveries related to complement-mediated neurodegeneration by the late Ben Barres, a neuroscientist and former chairman of Stanford University’s Department of Neurobiology known for his research into glial cells, underpinned the company’s formation. Barres in 2011 teamed up with former Genentech scientist Arnon Rosenthal, who served as its founding CEO, to start Annexon. (Rosenthal is also a co-founder of Alector (NASDAQ: ALEC), another neuroscience company based in South San Francisco, and, before that, co-founder and former chief scientist at Rinat Neuroscience.)

The biotech made its public debut in 2014 with $34 million in Series A backing. In 2016 it raised $44 million more; then, in December 2018, another $75 million. This month came its largest round yet, of $100 million.

Annexon’s largest outside shareholders are Bain Capital, which owns 13.4 percent of its shares; Clarus Lifesciences, which holds 11.9 percent; and NEA, with 11.7 percent. Novartis Bioventures has just shy of 10 percent.

—In other IPO news, Nurix Therapeutics, a preclinical-stage biotech developing drugs for cancer and immune diseases, submitted its IPO paperwork with securities regulators.

San Francisco-based Nurix is developing drugs based on protein degradation, a cell’s built-in system for disposing of old or damaged proteins. The idea is to use this cellular system to get rid of a problem protein before it causes disease. Nurix’s lead internal program, NX-2127, is being readied for Phase 1 testing as a potential treatment for B-cell lymphomas. The biotech also has research partnerships with Sanofi (NYSE: SNY) and Gilead Sciences (NASDAQ: GILD).

Nurix’s largest shareholder is The Column Group with a 26 percent stake in the company, followed by Third Rock Ventures, which owns 20.9 percent, according to the IPO filing. Bristol Myers Squibb (NYSE: BMY) holds a 10 percent stake, which came to the company via its acquisition of Celgene, another Nurix R&D partner. Nurix set a preliminary $100 million goal for its IPO. If it completes the stock offering, the company expects to trade on the Nasdaq under the stock symbol “NRIX.”

—Rare disease drug developer Inozyme Pharma filed for an IPO to advance its lead drug, a potential treatment for an enzyme deficiency, into clinical testing.

Boston-based Inozyme is developing a treatment for generalized arterial calcification of infants (GACI). The inherited disease is caused by a mutation to the ENPP1 gene, which codes for an enzyme that stops calcium from building up in blood vessels. Without enough of that enzyme, the calcium buildup leads to high blood pressure and heart problems. Inozyme’s drug candidate, INZ-701, is a fusion protein designed to correct the defect in the mineralization pathway at the root of GACI.

Inozyme’s largest shareholders are Longitude Venture Partners, New Enterprise Associates, and Novo Holdings, each owning 15.6 percent of the company, according to the IPO filing, The biotech set a preliminary $86.3 million goal for its IPO. The company plans to seek permission from US and European regulators to begin a Phase 1/2 study in the second half of this year. Inozyme has applied for a Nasdaq listing under the stock symbol “INZY.”

Frank Vinluan contributed to this report.

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