Nature of Organization and Operations	12 Months Ended
Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Organization and Operations	1. Nature of Organization and Operations Apellis Pharmaceuticals, Inc. (the “Company”) is a commercial-stage biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutic compounds to treat diseases with high unmet needs through the inhibition of the complement system, which is an integral component of the immune system, at the level of C3, the central protein in the complement cascade. The Company was incorporated in September 2009 under the laws of the State of Delaware. The Company’s principal executive offices are located in Waltham, Massachusetts. The Company’s operations since inception have been limited to organizing and staffing the Company, acquiring rights to product candidates, business planning, raising capital, developing its product candidates, commercializing EMPAVELI (pegcetacoplan) for the treatment of paroxysmal nocturnal hemoglobinuria (“PNH”) and commercializing SYFOVRE (pegcetacoplan injection) for the treatment of geographic atrophy secondary to age-related macular degeneration (“GA”). The Company is subject to risks common in the biotechnology industry including, but not limited to, raising additional capital, development by its competitors of new technological innovations, its ability to successfully complete preclinical and clinical development of product candidates and receive timely regulatory approval of products, market acceptance of the Company’s products, protection of proprietary technology, healthcare cost containment initiatives, and compliance with governmental regulations, including those of the U.S. Food and Drug Administration (“FDA”). Follow-on Public Offerings On February 22, 2023, the Company issued and sold 4,007,936 shares of common stock and, in lieu of common stock to investor who so chose, pre-funded warrants to purchase 2,380,956 shares of common stock in a follow-on offering, including 833,333 shares sold pursuant to the underwriters’ exercise in full of their option to purchase additional shares of common stock. The price to the public of the shares of common stock was $63.00 per share and the price to the public of the pre-funded warrants was $62.9999 per pre-funded warrant. The pre-funded warrants have an exercise price equal to $0.0001 per share and do not expire. The pre-funded warrants were accounted for as equity instruments. The Company received total net proceeds of $384.4 million, after deducting underwriting discounts and commissions of $18.8 million and offering costs of $0.3 million. On March 28, 2022, the Company issued and sold 8,563,830 shares of its common stock at a price per share to the public of $47.00 in a follow-on public offering including an additional 1,117,021 shares of its common stock that were sold at the follow-on public offering price of $47.00 per share pursuant to the underwriters’ agreement in full exercise of their option to purchase additional shares of common stock. The Company received net proceeds of approximately $380.1 million after deducting underwriting discounts and commissions of approximately $22.1 million and offering costs of $0.3 million for these transactions. On November 18, 2021, the Company issued and sold 10,062,500 shares of its common stock at a price per share to the public of $40.00 in a follow-on public offering including an additional 1,312,500 shares of its common stock that were sold at the follow-on public offering price of $40.00 per share pursuant to the underwriters’ agreement in full exercise of their option to purchase additional shares of common stock. The Company received net proceeds of approximately $380.4 million after deducting underwriting discounts and commissions of approximately $22.1 million and offering costs of $0.6 million for these transactions. Liquidity and Going Concern The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. From inception to December 31, 2023, the Company has incurred cash outflows from operations, losses from operations, and had an accumulated deficit of $2.8 billion, primarily as a result of expenses incurred through a combination of research and development activities related to the Company’s various product candidates and expenses supporting those activities. The Company has primarily financed its operations through public offerings of its common stock, convertible debt, private placements of preferred stock prior to its initial public offering, the development funding agreement with SFJ, and the collaboration agreement with Sobi. The Company has financed a portion of its operations through product sales but has not yet achieved profitability. The Company believes that its cash and cash equivalents of $351.2 million at December 31, 2023 and the cash anticipated to be generated from the unwind of the capped call transactions, together with cash anticipated to be generated from sales of EMPAVELI and from SYFOVRE will be sufficient to fund its operations and capital expenditure requirements for at least twelve months from the date of issuance of these consolidated financial statements.

Nature of Organization and Operations

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

1. Nature of Organization and Operations

Apellis Pharmaceuticals, Inc. (the “Company”) is a commercial-stage biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutic compounds to treat diseases with high unmet needs through the inhibition of the complement system, which is an integral component of the immune system, at the level of C3, the central protein in the complement cascade.

The Company was incorporated in September 2009 under the laws of the State of Delaware. The Company’s principal executive offices are located in Waltham, Massachusetts.

The Company’s operations since inception have been limited to organizing and staffing the Company, acquiring rights to product candidates, business planning, raising capital, developing its product candidates, commercializing EMPAVELI (pegcetacoplan) for the treatment of paroxysmal nocturnal hemoglobinuria (“PNH”) and commercializing SYFOVRE (pegcetacoplan injection) for the treatment of geographic atrophy secondary to age-related macular degeneration (“GA”).

The Company is subject to risks common in the biotechnology industry including, but not limited to, raising additional capital, development by its competitors of new technological innovations, its ability to successfully complete preclinical and clinical development of product candidates and receive timely regulatory approval of products, market acceptance of the Company’s products, protection of proprietary technology, healthcare cost containment initiatives, and compliance with governmental regulations, including those of the U.S. Food and Drug Administration (“FDA”).

Follow-on Public Offerings

On February 22, 2023, the Company issued and sold 4,007,936 shares of common stock and, in lieu of common stock to investor who so chose, pre-funded warrants to purchase 2,380,956 shares of common stock in a follow-on offering, including 833,333 shares sold pursuant to the underwriters’ exercise in full of their option to purchase additional shares of common stock. The price to the public of the shares of common stock was $63.00 per share and the price to the public of the pre-funded warrants was $62.9999 per pre-funded warrant. The pre-funded warrants have an exercise price equal to $0.0001 per share and do not expire. The pre-funded warrants were accounted for as equity instruments. The Company received total net proceeds of $384.4 million, after deducting underwriting discounts and commissions of $18.8 million and offering costs of $0.3 million.

On March 28, 2022, the Company issued and sold 8,563,830 shares of its common stock at a price per share to the public of $47.00 in a follow-on public offering including an additional 1,117,021 shares of its common stock that were sold at the follow-on public offering price of $47.00 per share pursuant to the underwriters’ agreement in full exercise of their option to purchase additional shares of common stock. The Company received net proceeds of approximately $380.1 million after deducting underwriting discounts and commissions of approximately $22.1 million and offering costs of $0.3 million for these transactions.

On November 18, 2021, the Company issued and sold 10,062,500 shares of its common stock at a price per share to the public of $40.00 in a follow-on public offering including an additional 1,312,500 shares of its common stock that were sold at the follow-on public offering price of $40.00 per share pursuant to the underwriters’ agreement in full exercise of their option to purchase additional shares of common stock. The Company received net proceeds of approximately $380.4 million after deducting underwriting discounts and commissions of approximately $22.1 million and offering costs of $0.6 million for these transactions.

Liquidity and Going Concern

The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. From inception to December 31, 2023, the Company has incurred cash outflows from operations, losses from operations, and had an accumulated deficit of $2.8 billion, primarily as a result of expenses incurred through a combination of research and development activities related to the Company’s various product candidates and expenses supporting those activities. The Company has primarily financed its operations through public offerings of its common stock, convertible debt, private placements of preferred stock prior to its initial public offering, the development funding agreement with SFJ, and the collaboration agreement with Sobi. The Company has financed a portion of its operations through product sales but has not yet achieved profitability.

The Company believes that its cash and cash equivalents of $351.2 million at December 31, 2023 and the cash anticipated to be generated from the unwind of the capped call transactions, together with cash anticipated to be generated from sales of EMPAVELI and from SYFOVRE will be sufficient to fund its operations and capital expenditure requirements for at least twelve months from the date of issuance of these consolidated financial statements.