Read on Twitter
$ATNM story: Non-targeted high dose radiation followed by bone marrow transplant is a preferred method to treat blood cancers in patients under 55. The success of this therapy relies on the radiation dose: it needs to be high to prevent relapse/BMT rejection. This is (1/n)
exemplified by the fact that young patients who received 15ghz of radiation had 0% relapse, whereas those who received 12ghz had 25%. Non-targeted radiation at these doses is too harsh for elderly. Thus radiation+BMT is not a viable option for this age group, and they (2/n).
typically go through chemo+BMT, which has a 10% 1yr OS for r/r. $ATNM's lead asset Iomab-B is an antibody that specifically binds blood cancer and stem cells. Iomab-B carries iodine-131, a particle that emits 4 bursts of beta particles over ~16 hours. Thus, it can deliver (3/n)
radiation that generates DNA damage directly at the site of cancer, while avoiding things such as liver damage. Interestingly, Iomab-B was able to achieve 15ghz directly at the bone marrow at the tolerable dose for pts. 55+. In ph2, it achieved a 30% 1yr OS, beating SOC. It (4/n)
is now in the ph3 SIERRA trial, which is expected to release topline data in Q4. Data at 50% enrollment already has been released. In treatment arm, 78% of patients engrafted with allogeneic HCT and did not relapse after 100 days. In control arm, which used physician's (5/n)
choice, only 13% had CRs, engrafted, and did not relapse after 100 days. Readout in Q4 is for 180 day durable CR. Even if we assume all patients in control arm have a dCR, 83% of treatment arm patients would have to relapse to have a comparable efficacy. Furthermore, (6/n)
patients on treatment arm took ~30 days to receive HCT, while patients on placebo arm took 67 days, and Iomab-B shows much more rapid kinetics for blast depletion. Faster timelines correlate with higher durable response rate. Finally, Iomab-B showed significantly less AEs (7/n
compared to SOC. Imo, Iomab-B is clinically de-risked, and betting on the ph3 trial is a high EV play. Scientific rationale is strong and clinical value proven. BMT market has steadily grown in last decade, and treatment will open it up to new patient population. (8/n)
Single infusion + less toxicity + 3x increased chance of 1 year survival compared to SOC is desirable to patient. I've seen opinions on physician's not wanting to turn away from SOC due to their bottomline, but will be hard to convince patient given these numbers imo.
