Could someone explain this immunity question

This q is from a past paper.
Scientists investigated whether one type of ADC could be used to treat human breast cancer.
This ADC is a monoclonal antibody combined with a drug to inhibit mitosis. The monoclonal antibody binds to a protein found on human breast cancer cells.
The scientists placed small pieces of human breast cancer tissue under the skin of mice.
The scientists then randomly divided the mice into three groups. They treated the groups as follows on day 0.
Group G - control
Group H - injected with monoclonal antibody only
Group J - injected with ADC (monoclonal antibody + drug).
Every few days, the scientists measured the volume of the tumours formed from the human breast cancer tissue.
Suggest one reason why there are no data for Group G and Group H after day 8.
The MS says mice died but I don’t get why they would die
This q is on PMT aqa topic wise questions- the immune system. You can find the graph there too.
Thank you

They died of cancer?