Homyk v. ChemoCentryx, Inc.

District Court, N.D. California·Decided May 30, 2025·No. 4:21-cv-03343·Unknown

Opinion

JONNIE HOMYK, et al., Case No.21-cv-03343-JST Plaintiffs, ORDERRESOLVINGMOTIONS TO v. EXCLUDE CHEMOCENTRYX, INC., et al., Re: ECF No. 188, 190, 191, 193–99, 206 Defendants. REDACTED VERSION Before the Court are the parties’ motions to exclude evidence under Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). This order addresses Defendants ChemoCentryx, Inc. (“ChemoCentryx”) and Dr. Thomas J. Schall’s (together, “Defendants”) motions to exclude testimony of Dr. Alan Bonder, Dr. Simon Helfgott, Dr. David Madigan, and Dr. Matthew Cain, and Lead Plaintiff Indiana Public Retirement System’s motions to exclude testimony of Dr. Anisha Dua, Dr. Naga Chalasani, Dr. Lindsay Lally, Dr. Steven Weisman, Dr. Robert Gibbons, Dr. Anupam Jena, and Mr. Carl Seiden. ECF Nos. 188, 190, 191, 193–99, 206. The Court will deny the motion as to Cain and grant the motions as to Jenaand Lally. The Court will grant in part and deny in part the remainder of the motions. I. BACKGROUND1 Lead Plaintiff Indiana Public Retirement System brings this action individually and on behalf of all persons who purchased or otherwise acquired ChemoCentryx common stock between November 26, 2019, and May 6, 2021, inclusive (“Class Period”). Plaintiff alleges that ChemoCentryx and Dr. Schall, its President and Chief Executive Officer, violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 by making false and misleading statements and omissions about the safety, efficacy, and application for Food and Drug Administration (“FDA”) approval of a proprietary vasculitis drug called avacopan, thereby artificially inflating the price of ChemoCentryx stock during the Class Period. Plaintiff also alleges that Dr. Schall is liable for insider trading under Section 20A of the Securities Exchange Act. ChemoCentryx is a pharmaceutical company specializing in drugs designed to treat rare diseases. ECF. No. 47 ¶ 5. The company developed avacopan, which Defendants presented as a breakthrough therapy for the treatment of ANCA-associated vasculitis (“AAV”), a rare autoimmune disease. Id. Physicians had been treating AAVwith a combination of steroids and immunosuppressants. Id.¶ 48. Defendants described avacopan as a drug that would transform the standard of care for AAV, in part by replacing steroid treatment,the long-term use of which presented safety risks for patients. Id.¶ 1. At the start of the Class Period, Defendants announced the results of a study called ADVOCATE, the Phase III trial of avacopan for the treatment of AAV. Id. ¶ 10. ADVOCATE was designed to provide evidence to support ChemoCentryx’s application for FDAapproval of avacopan. Id.¶ 2. Throughout the Class Period, Defendants stated that trial safety results showed that avacopan was safer than standard-of-care steroid therapy; that, in the trial, avacopan had demonstrated non-inferiority versus prednisone with respect to the primary endpoint of Birmingham Vasculitis Activity Score (“BVAS”) remission at week 26 and superiority at week 52; that the study demonstrated that chronic steroids were not needed to achieve remission; and that communications with the FDA regarding the avacopan New Drug Application (“NDA”) had been straightforward. Id. However, in private communications with Defendants in 2016 and 2020, the FDA had expressed concerns about the trial’s design and results. The FDA repeatedly told Defendants that ADVOCATE was “likely not adequate” to demonstrate, or even assess, whether using avacopan as a “replacement for glucocorticoids [] will provide an improved benefit-risk profile.” Id. ¶ 86. Specifically, the FDA told Defendants that statistical non-inferiority would be inadequate to sufficiency of ADVOCATE’s key week 26 results. Id.¶¶ 96–100. The FDA also warned Defendants that ADVOCATE’s relapse data was unreliable because those analyses failed to preserve study randomization and were not adjusted for multiplicity. Id.¶¶ 101–03, 110-22. The FDA further indicated “that avacopan was efficacious only in the population who did not receive standard-of-care maintenance,” raising questions about the meaning of the study’s results. Id.¶¶107–08. Plaintiff alleges that Defendants knowingly withheld adverse facts from investors during the Class Period. For example, Plaintiff alleges that Defendants knew that steroid use was significant and widespread among avacopan patients enrolled in the trial. Id. ¶¶ 138–46. The majority of avacopan patients were prescribed the steroid prednisone during the trial to control their vasculitis, and ChemoCentryx considered such patients to have responded to avacopan in its analysis of trial data, despite their significant steroid use. Id. Plaintiff alleges that Defendants knew that these adverse facts undermined their public statements about the comparative safety and efficacy of avacopan and standard-of-care steroid therapy. Id. Plaintiff also alleges that Defendants knew of and failed to disclose serious adverse liver events, including an event meeting Hy’s Law criteria2 and one occurring after rechallenge, that occurred during the trial. ECF No. 47¶ 128. Further, Plaintiff alleges that ChemoCentryx did not disclose its failure to follow trial protocol in calculating remission results. When these results were later calculated in accordance with trial protocol, avacopan failed to achieve superiority to standard-of-care steroid therapy at week 52 by a statistically significant margin. Id.¶¶ 130–37. Plaintiff alleges that Defendants’ misleading statements about the success of the avacopan trial and the prospective NDA submission artificially inflated ChemoCentryx’s stock price during the Class Period, enriching both Dr. Schall and ChemoCentryx. During the 17-month Class 2 “A Hy’s Law case involves significant elevations in both a patient’s serum levels of aminotransferase (enzyme leaked by injured cells) and increases in bilirubin, indicating the liver injury is significant enough to impair liver function. . . . [T]he occurrence of even one case Period, Dr. Schall sold more than 893,300 shares of ChemoCentryx stock—representing nearly 20% of his ChemoCentryx holdings—and earned proceeds of over $40.3 million. Id.¶¶ 152–54. The market learned the extent of the FDA’s concerns about the trial in early May 2021. On May 4, the FDA published the Briefing Book and other materials (together, “Advisory Committee Materials”) in advance of its Advisory Committee meeting. The concerns reflected in these documents mirrored many of the concerns the FDA had privately expressed to ChemoCentryx in 2016 and 2020. Id.¶ 17. These materials further revealed, among other things, the extent of steroid use among avacopan patients in the trial. Id. In response to the release of the Advisory Committee Materials, ChemoCentryx’s common stock dropped more than 45% in a single day. Id.¶18. Analysts and investors expressed surprise at the scope of the FDA’s criticism of the trial and the fact that ChemoCentryx had not disclosed the FDA’s concerns. Id. On May 6, 2021, the Advisory Committee held a public meeting to discuss avacopan. The Advisory Committee meeting revealed that ADVOCATE’s supposed “superiority” results were the product of violations of the prespecified trial rules. Id.¶ 19. This meeting, Plaintiff alleges, also allowed investors to appreciate the significance of the previously concealed facts discussed in the FDA Briefing Book, including the clinical import of the ADVOCATE results. Id. Advisory Committee members were evenly split on the question of whether the drug should be approved, and those who voted in favor of approval argued its label should be limited—that is, that it should only be approved for use by a limited set of patients. The next day, ChemoCentryx common stock fell by approximately 62%. Id. Overall, ChemoCentryx’s share price fell 79% over four days, from $48.82 on May 3, 2021, to $

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Homyk v. ChemoCentryx, Inc., (N.D. Cal. 2025).

Homyk v. ChemoCentryx, Inc. (Homyk v. ChemoCentryx, Inc.) — published by Counsel Stack Legal Research, free access to 12M+ legal documents.

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