For P/E ratio  we finally planning to use AF1MN;AF2MN;AF3MN  which are forecasted earnings by IBES and we divide that with daily price   to get the more accurate P/E ratios and our business as approved it now.
But when we are requesting using API , unfortunately it is returning Price  instead of earnings value. Can check this with high priority as we need to develop and deploy ASAP. 
DATASTREAM FORMULA 
=DSGRID("@:JPTOPIX","AF1MN;AF2MN;AF3MN","-4M","","D","RowHeader=true;ColHeader=true;Heading=true;Code=true;LatestFirstValue=true;DispSeriesDescription=false;YearlyTSFormat=false;QuarterlyTSFormat=false","")
DATASTREAM API CALL using postman -  ( FYI the code is working and returning other standard values as excepted ) 
Please find the screen shots below for the AF1MN from DataStream. Its returning Price 
Request

Response