IDYA

• Yujiro Hata provided an overview of the IDE397 program update, including the GSK option data package requirements, collaboration with GSK, and the agenda for the call. • Dr. Matt Maurer walked through the Phase 1/2 clinical development plan, preclinical pharmacokinetic data showing favorable PK profile, and safety experience with manageable adverse events. • Michael White discussed preclinical and clinical pharmacodynamic biomarker data, including dose-dependent reduction of tumor SDMA and plasma SAM reduction. • Paul Stone reported financial results for 2021, and provided updates on other programs: Darovasertib enrolling patients, IDE161 targeting IND in Q4 2022, Pol Theta in IND-enabled settings first half 2022, and Werner Helicase development candidate with GSK in 2023.

• Deliver the GSK option data package by midyear 2022. • Initiate monotherapy expansion and combination studies in mid-year 2022. • IDE161 targets IND submission in Q4 2022. • Pol Theta is expected to be in IND-enabled settings by the first half of 2022. • Werner Helicase development candidate with GSK is targeted for 2023.

In 2021, operating expenses were $78 million. The company had a cash balance of $368 million, providing a runway for operations into 2025. No detailed revenue contributions from specific product segments were discussed as the focus was on program updates and financials.

• Uncertainty regarding the timeline for GSK's review and opt-in decision on the IDE397 program. • Variability in clinical response and the timing required to observe significant effects based on SDMA and SAM reduction. • Potential challenges related to the AE profiles of previous compounds in the same pathway, though IDE397 shows a more favorable profile.

Q: Can you remind us when the data upload to GSK is complete to midyear, how long GSK has to make a formal opt-in decision, and disclosure of package delivery or GSK decision?

A: Yujiro Hata stated the timeframe for GSK's review isn't disclosed, but there's close communication with GSK, and hope the package delivery and GSK's decision are in close proximity.

Q: What exactly is submitted to GSK, impact of Cohort 6 dosing?

A: Yujiro Hata said data categories are as per earlier slides, and it depends on the outcome of Cohort 6 dosing.

Q: Thoughts on SDMA and SAM reduction duration for clinical response?

A: Michael White explained it's a multi-step mechanism with time required for splicing perturbation and protein milieu change, with indication-specific timing.

Q: Requirement for GSK to show MTD before opt-in, likelihood?

A: Yujiro Hata noted the option package is based on expansion dose selection, not requiring MTD, with scenario-based dose selection possible.

Q: Correlation between SDMA/SAM reduction and tumor reduction, variability?

A: Michael White said preclinically a threshold of SDMA reduction is needed for response, and clinical data is limited but CT scans show tumor shrinkage; variability in tumor type and baseline characteristics requires a larger data set for full comment.