This trial is for people with melanoma. This trial is testing the V940 (mRNA-4157) vaccine given in combination with pembrolizumab in people who have surgery to remove their melanoma. The vaccine has multiple patient-specific neoantigens that could improve the recurrence-free survival after the surgery. Each participant will participate in the study for approximately 7 years from the time the participant provides full documented informed consent through the final contact. There is a screening window of up tp 56 days where the participants receives tumor scan, brain scan, pathology report, hematology, coagulation tests, hormones, enzymes, and blood for genetic sequencing and vaccine generation. After a screening period of up to 56 days, each participant will be receiving assigned intervention for a maximum of approximately 56 weeks. The participants will be assigned to the two arms in the study randomly after the genetic testing confirms eligibility based on disease risk and age. Arm A will receive and a V940 injection in the muscle every 3 weeks for a total of 9 doses and pembrolizumab ever 6 weeks for a total of 9 cycles. Arm B will receive Placebo every 3 weeks for 9 dose and pembrolizumab every 6 weeks for 9 cycles. After the end of treatment each participant will be followed for approximately 6 years. V940 monotherapy has been well tolerated, but injection site observations included edema and pain/tenderness, and systemic inflammatory observations, including flu like symptoms, fever, fatigue, and myalgias/arthralgias, all of which have typically resolved 1 to 2 days after dosing). The clinical safety profile of V940 does not significantly overlap with pembrolizumab. Pembrolizumab has a positive benefit-risk profile and is well tolerated. Some possible risks associated with pembrolizumab are fatigue, pruritus , rash , diarrhea, nausea, hypothyroidism, pneumonitis, colitis, pyrexia and autoimmune hepatitis, pneumonia, adrenal insufficiency and hyponatremia.

The primary trial objective is to see if the study drug called BI 907828 may help people with dedifferentiated liposarcoma (DDLPS) and is better than the approved drug, doxorubicin.
Additional trial goals are to find an optimal dose of BI 907828
and to determine whether BI 907828 improves the response
rate, duration of response, overall survival, disease control rate, the tolerability and if the study drug has a positive impact on the quality of life, compared to doxorubicin.