Annexon Biosciences Secures $75M Series C Led by Bain Capital Life Sciences with Participation from NEA and Novartis to Advance C1q-Targeted Therapies Against Neurodegenerative and Autoimmune Diseases

Recently, VCBeat (WeChat Official Account: vcbeat) learned from foreign media reports that U.S. biotechnology company Annexon Biosciences (“Annexon”) announced on December 19 (local time) the completion of a $75 million Series C financing round. The round was led by Bain Capital Life Sciences, with participation from Surveyor Capital and Adage Capital Management. Existing investors, including New Enterprise Associates (NEA), Blackstone Life Sciences, Novartis Venture Fund, and Satter Investment Management, also made additional investments.

Annexon, founded in 2011, is a clinical-stage biopharmaceutical company focused on developing novel therapies for neurodegenerative and autoimmune diseases. The company’s researchers discovered the role of the classical complement pathway in synaptic elimination within the central nervous system and, based on this finding, developed an anti-complement platform. This platform aims to create new treatments for neurological disorders by developing inhibitors of the classical complement pathway.

The classical complement pathway plays a crucial role in immunity, defense against pathogens, and the repair of damaged tissues. However, dysfunction and dysregulation of this complement pathway constitute the core pathogenesis of many diseases. These diseases are characterized by aberrant autoimmune responses against healthy host tissues. This misguided immune response leads to the activation of C1q, the initiating molecule of the classical complement pathway. Consequently, C1q and the classical complement pathway erroneously recruit microglia, the resident immune cells of the brain, to become activated. These activated microglia recognize and phagocytose complement-coated synapses and secrete pro-inflammatory cytokines, ultimately resulting in neuronal loss.

In preclinical studies, Annexon targets C1q, with its primary drug candidates being ANX005 and ANX007.

ANX005 is an intravenously administered humanized anti-C1q monoclonal antibody that inhibits the entire classical pathway by targeting C1q, while preserving the integrity of the lectin and alternative pathways. ANX005 has demonstrated efficacy in preclinical models of several diseases.

ANX007 shares the same C1q inhibitory properties as ANX005 and is indicated for ophthalmic conditions such as glaucoma and geographic atrophy. The drug is currently undergoing a Phase 1b proof-of-concept study, with results expected to be released in 2019.

Doug Love, CEO and President of Annexon, stated that over the past two years, Annexon has made significant progress in building a portfolio of candidate products for multiple indications. The proceeds from this financing round will be used to advance several key clinical-stage programs targeting antibody-mediated autoimmune, ophthalmic, and neurodegenerative indications, including the completion of proof-of-concept trials.

Mechanism of Action of Annexon’s Lead Candidate Drug (Image source: Annexon Biosciences official website)

Ruiqi Sun, Partner at Bain Capital Life Sciences, said, “We are deeply impressed by the progress the Annexon team has made in the field of classical complement, and we look forward to collaborating with the team to develop promising, transformative therapies.” Following the completion of the financing, Ruiqi Sun joined the Board of Directors of Annexon.

In the field of Alzheimer’s disease, Annexon’s primary competitors include pharmaceutical giants such as AstraZeneca, Johnson & Johnson, and Merck, as well as biopharmaceutical startups like Alector and NeuroTherapia. These companies have invested substantial capital and human resources into Alzheimer’s research and have been rolling out new products. Despite the strength of its competitors, leading investment firms—headed by Bain Capital Life Sciences, Novartis Venture Fund, and NEA—remain highly optimistic about Annexon’s prospects, as evidenced by the company’s prior financing history.

In August 2011, the newly established Annexon secured $1 million in seed funding. In December 2014, the company completed a $34 million Series A financing round led by Novartis Venture Fund. In June 2016, Annexon raised $44 million in its Series B round, led by New Enterprise Associates (NEA) and participated by three investors including Novartis Venture Fund. As of this financing round, the company’s total funding had reached $154 million.

Surveyor Capital, established in 2008, is a financial services firm and one of the four core equities businesses under Citadel, a global financial services group. At the heart of Surveyor’s investment process, the investment team focuses on understanding each company’s strategy, management team, performance drivers, as well as cyclical and long-term industry trends.

Adage Capital Management is a Boston-based asset management firm that primarily manages endowments for institutions such as Harvard University, Northwestern University, and Dartmouth College, as well as assets comprising the S&P 500 Index constituents.

Satter Investment Management, headquartered in the United States, is a venture capital firm focused on the life sciences and medical technology industries.