Material Event Form 8 K

Item 8.01

Other Events.

On August 8, 2024, Apellis Pharmaceuticals, Inc. ("Apellis") and Sobi^®announced positive topline results from the Phase 3 VALIANT study investigating systemic pegcetacoplan in patients with C3 glomerulopathy (C3G) or primary immune complex membranoproliferative glomerulonephritis (IC-MPGN),which are rare kidney diseases with no approved treatments.

The study met the primary endpoint, demonstrating a statistically significant and clinically meaningful 68% (p<0.0001) proteinuria reduction (log-transformedratio of urine protein-to-creatinineratio) in C3G and IC-MPGNpatients treated with pegcetacoplan compared to placebo, both in addition to background therapy, at Week 26. Results were consistent across all subgroups, including C3G and IC-MPGN,adolescent and adult patients, and native and post-transplant kidneys.

Pegcetacoplan also demonstrated statistical significance on the key secondary endpoints of composite renal endpoint, which combines proteinuria reduction and estimated glomerular filtration rate (eGFR) stabilization, and proteinuria reduction of at least 50 percent compared to baseline, as well as nominal significance on the histological endpoint of reduction in C3c staining on kidney biopsy and stabilization of kidney function as measured by eGFR compared to placebo.

In the VALIANT study, pegcetacoplan demonstrated favorable safety and tolerability results, consistent with its established profile. Rates of adverse events (AEs), serious AEs, and AEs leading to study drug discontinuation were similar between the pegcetacoplan and placebo groups. There were no cases of meningitis or serious infections attributed to encapsulated bacteria.

All patients who have already completed the VALIANT study have now enrolled into the VALE long-term extension study.

Apellis plans to submit a supplemental new drug application to the U.S. Food and Drug Administration in early 2025, and Sobi plans to submit a marketing application with the European Medicines Agency in 2025. Detailed data will be presented at an upcoming medical congress.

Forward-Looking Statements

Statements in this Current Report on Form 8-Kabout future expectations, plans and prospects, as well as any other statements regarding matters that are not historical facts, may constitute "forward-looking statements" within the meaning of The Private Securities Litigation Reform Act of 1995. These statements include, but are not limited to, statements regarding plans to submit applications for regulatory approval for the treatment of patients with C3G and IC-MPGN.The words "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "should," "target," "will," "would" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including whether systemic pegcetacoplan will receive approval for those indications from the FDA or equivalent foreign regulatory agencies when expected or at all; and any other factors discussed in the "Risk Factors" section of Apellis' Annual Report on Form 10-Kwith the Securities and Exchange Commission on February 27, 2024 and the risks described in other filings that Apellis may make with the Securities and Exchange Commission. Any forward-looking statements contained in this Current Report on Form 8-Kspeak only as of the date hereof, and Apellis specifically disclaims any obligation to update any forward-looking statement, whether as a result of new information, future events or otherwise.