A Phase 1/1b Study of VET3-TGI Administered Alone and in Combination with Pembrolizumab in Patients with Advanced Solid Tumors

• VET3-TGI is an attenuated, recombinant vaccinia virus designed to deliver the transgenes IL-12 and TGF-β inhibitor

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

• How much of the study agent can be given with an acceptable level of side effects
• The effects of the study agent (good and bad)
• How much of the study agent is absorbed into the blood and how fast it is removed
• How the study agent is acting on your body
• If research tests can be used in the future to predict who will benefit from VET3-TGI

There are two stages in this study based on how often you return to the clinic or are contacted by study staff. In the first stage, we will ask you to come into the clinic or contact you via phone or virtually every week for 8 weeks. You may or may not receive a dose of VET3-TGI. In the second stage, which starts 10 weeks after you receive your first dose of VET3-TGI, you will be asked to return to the clinic every 6 weeks for up to 2 years, depending on how well you are doing.

The number of treatments you receive will depend on the route VET3-TGI is given to you. If you are assigned by your study doctor to receive VET3-TGI via a direct injection into 1 to 3 of your tumors, called an intratumoral (ITu) injection, you will return for four straight weeks to receive VET3-TGI. If you are assigned to receive VET3-TGI via an infusion directly into your vein, called an intravenous(IV) infusion, you will return for 6 straight weeks. Regardless of the treatment route, all participants will be contacted weekly and will have to come into the clinic on Week 8 to scan their tumor(s) and see how they are doing. If your cancer is stable or getting better, you will have a short break and then enter the second phase of the study, where you will return to the clinic every 6 weeks. At this time, you may receive additional VET3-TGI treatments using the same route and dose you started the study with, if your study doctor believes you may benefit from these treatments. These are called booster treatments. You do not have to receive booster treatments to remain in the study.

Some participants may be assigned to receive VET3-TGI, either injected into their tumor or infused into the vein, with pembrolizumab. These participants will start pembrolizumab after 2 VET3-TGI treatments (Week 1 / Day 8) via an IV infusion. The timing of the pembrolizumab may be later the same day as the study drug, or it could be the next day. That decision is left up to you and your study doctor. Pembrolizumab will be given every 3 weeks for the first portion of the study until Week 8 and then will be given every 6 weeks. If you join this research, we will ask you to come to the research site for approximately 36 visits over 2 years.