Small cap Geron was down by nearly 20% at the end of Monday after releasing new data with partner Janssen ($JNJ) that showed a low-dose arm of its experimental med imetelstat flopped, with the higher dose arm also coming up short. The IMbark study was assessing patients with myelofibrosis (MF) taking a high- and low-dose form of its treatment who have relapsed after or are refractory to prior treatment with a marketed JAK inhibitor. Its low-dose formulation (4.7 mg/kg) missed the mark, with Geron ($GERN) saying that arm now does "not warrant further investigation" and will be closed off. Patients using the low dose can be moved over to the higher dose (9.4 mg/kg) should they want to, although data released for this arm was also poor, as "an insufficient number of patients met the protocol defined interim criteria," according to the biotech's statement.