Thant v. Karyopharm Therapeutics Inc., 43 F.4th 214

Karyopharm developed selinexor and ran multiple clinical trials: Phase 1 (KCP‑330‑001), Phase 2 SOPRA (terminated for lack of benefit and high toxicity), Phase 2b STORM (single‑arm, penta‑refractory myeloma), and Phase 3 BOSTON (randomized).
STORM reported ~25% response but substantial toxicity: frequent dose modifications (≈88.6%), numerous treatment‑emergent adverse events (TEAEs), and ~18 TEAE‑related deaths.
Karyopharm submitted an NDA on Aug. 5, 2018; FDA raised concerns that a single‑arm trial might not establish safety/efficacy, and ODAC materials (Feb. 22, 2019) emphasized these limitations; Karyopharm stock fell after the briefing.
Plaintiff Myo Thant led a securities class action alleging Karyopharm made materially misleading statements about STORM safety/efficacy (notably an Apr. 30, 2018 press release saying selinexor had a "predictable and manageable tolerability profile" and a May 1, 2018 CEO statement calling STORM "an important milestone").
The district court dismissed for failure to plead scienter; the First Circuit affirmed but on alternative grounds: the challenged statements were non‑actionable puffery or not materially misleading given prior disclosures and market awareness of toxicity.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether STORM statements (Apr. 30 press release; May 1 CEO remarks) were materially false or misleading	Thant: statements omitted known, severe AEs and overstated tolerability and efficacy, which would have altered the total mix for investors	Karyopharm: statements were generic optimism/puffery and not interpreted to mean the drug was benign; market already knew about toxicity and FDA risk	Held: Statements were non‑actionable puffery or not materially misleading given prior disclosures and context; not a viable basis for §10(b)/Rule 10b‑5 claims
Whether plaintiff pleaded scienter with particularity under the PSLRA	Thant: alleged former‑employee reports of concealment, pressure to downplay AEs, FDA clinical hold, and other facts support a strong inference of recklessness/intent	Karyopharm: former‑employee allegations are insufficiently tied to the speakers and explainable as non‑culpable conduct; disclosure of the FDA hold undermines inference of intent	Held: Court did not reach scienter in depth because materiality failings disposed of the case; district court had found scienter inadequately pleaded

Matrixx Initiatives, Inc. v. Siracusano, 563 U.S. 27 (2011) (materiality: omitted facts must be likely to alter the total mix of information)
Basic Inc. v. Levinson, 485 U.S. 224 (1988) (materiality standard and the total‑mix inquiry)
Yan v. ReWalk Robotics Ltd., 973 F.3d 22 (1st Cir. 2020) (company optimism/puffery is non‑actionable)
In re Ariad Pharms., Inc. Sec. Litig., 842 F.3d 744 (1st Cir. 2016) (contrast: actionable when company knowingly mischaracterizes FDA communications or AE prevalence)
Backman v. Polaroid Corp., 910 F.2d 10 (1st Cir. 1990) (disclosure of some facts does not require disclosure of all "interesting" information)
Baron v. Smith, 380 F.3d 49 (1st Cir. 2004) (no duty to disclose information of which the market is already aware)
In re Biogen Inc. Sec. Litig., 857 F.3d 34 (1st Cir. 2017) (elements required for a §10(b) claim)
ACA Fin. Guar. Corp. v. Advest, Inc., 512 F.3d 46 (1st Cir. 2008) (PSLRA scienter pleading standard)