concatenate cell value with substitute

Dear all, concatenate cell value with substitute

 CELL B1     CELL C1      CELL D1
 BSE01	ETM2-0	0
 BSE01	ETM2-0	1

i want like below in the cell A1 & A2 other then cell keeping as blank

 BSE01_0ETM2_MS-0
 BSE01_0ETM2_MS-1

It is something like as

A1=  B1&"_"&SUBSTITUTE(C1,"ETM2","")&"ETM2"&"_MS-"&D1