Why does the drug MCP help so well?

Last year, I was diagnosed with a very rare tumor. It damaged my esophagus and metastasized to multiple organs. The esophageal condition improved with medication (pantoprazole and Suctabest).

But since the beginning of the year, I've been undergoing chemotherapy with tablets. Swallowing so many tablets (one of the medications is quite large) has caused my esophagus to get worse again. I often felt a tightness while eating and had to spit up mucus, sometimes for several hours.

In oncology

At the outpatient clinic where I go every two weeks, the doctors were a bit confused and didn't know what to do about it.

On Good Friday, I called the emergency medical service because I couldn't even eat yogurt without spitting up.

They then sent a doctor to my home. He prescribed me a really great medication, MCP. This medication is like a miracle cure. All my symptoms are gone. I asked my family doctor if the medication could repair my esophagus. She said no.

So why does the drug work so well?