A Phase 1/2, Open-Label, Multicenter Study of Oral MRT-2359 in Patients with MYC-driven and Other Selected Solid Tumors Including Lung Cancer and Diffuse Large B-Cell Lymphoma

MRT-2359 induces degradation of GSPT1 and associated downregulation of MYC transcription factors and their transcriptional outputs, which may lead to preferential anti-proliferative activity in MYC-driven tumors.

In this study, the sponsor and investigators want to learn:

• How much of MRT-2359 can be given with an acceptable level of side effects
• The effects of MRT-2359 (good and bad)
• How much of MRT-2359 is absorbed into the blood and how fast it is removed

This is a dose escalation/expansion study. This means that in the dose escalation part of the study, the study drug given will be increased in each group of research participants, to find the most appropriate dose for further study. In the dose expansion part of the study, a larger number of people receive the study drug dose determined to be appropriate in the dose escalation part of the study.

The study regimen will be given in cycles. Each cycle is 28 days. The study drug will be taken by mouth, once a day at about the same time each day, preferably in the morning.

You will follow one of two possible dosing schedules as instructed by your study doctor:

5 Days On/ 9 Days Off/ 5 Days On/ 9 Days Off Schedule:

In this schedule, you will receive the study drug for the first 5 days, followed by 9 days off, then you will take the study drug again for 5 days, followed by another 9 days off each cycle.

21 Days On/ 7 Days Off Schedule:

In this schedule, you will receive the study drug for the first 21 days, followed by 7 days off each cycle.