Why Magenta Therapeutics (MGTA) Stock Is Plunging Today

Magenta Therapeutics Inc MGTA has stopped dosing participants at the Cohort 4 dosing level (0.13 mg/kg) of the MGTA-117 Phase 1/2 Dose Escalation Trial in relapsed/refractory acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS).
The company plans to dose additional participants at the Cohort 3 dosing level (0.08 mg/kg).
Three participants were dosed in Cohort 4, and dose-limiting toxicities (DLTs) were observed in the second and third dosed participants.
The first participant completed the 21-day DLT observation period with no DLTs. The second-dosed participant in Cohort 4 experienced a Grade 4 Serious Adverse Event (SAE) (respiratory) considered possibly related to MGTA-117.
This SAE was later determined to be a DLT and a Suspected Unexpected Serious Adverse Reaction (SUSAR) due to lung involvement.
This participant also experienced Grade 4 elevated liver enzyme levels.
Magenta plans to continue enrollment at the Cohort 3 dose level.
As presented at the 2022 American Society of Hematology Annual Meeting, no DLTs were observed in the fifteen participants dosed in the first three Cohorts in the clinical trial.
Price Action: MGTA shares are down 51.70% at $0.41 on the last check Tuesday.

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