I need to use custom variables for my DOCX file content created from Markdown file.

Tried to insert DOC_NAME variable in "--reference-doc" template file both using LibreOffice and MS Office in document header. Then I redefine this variable according to pandoc man page and convert Markdown to DOCX using this command line:

$ pandoc -s -V DOC_NAME=DOCUMENT1 --columns 10 --reference-doc=template.docx -s -f markdown -t docx main.md -o main.docx

But when I open main.docx I see variable values that was set in office document editor in template.docx header, not what was set in command line. E.g. I set variable DOC_NAME=doc1 in office and see it in resulting file, not the "DOCUMENT1" value that was set in command line.

Could anybody help me with setting custom variables?