Really, space marines are a concept for a lot of things ranging from the Gears of War series to the ultimate protectors of mankind of the games workshop table top battle game company. If you mean by highly armored humans then yes they do have suits that can protect humans from most normal gunfire and explosives. (prototype that costs around 4bn at the last estimate) the problem is that military organizations do not have the money to equip people with this kind of protection and it would be cheaper to buy low grade nukes. on the other hand, if you mean by really strong (maybe genetically altered) people then that is mostly science fiction. There are combat drugs but not the type of stuff that could give humans the power to headbutt a brick wall and watch it fall down like it was a jenga tower. Really genetic enhancement could be a reality but it's morality that is stopping this from being reality. Also imagine how hard it would be to counter, if people could have the strength of over ten men. it would be catastrophic for the human race. Also you have to take into the account of muscle size as you are limited by your structure as a human being while lets say a lion would have a lot more muscular strength. so all in all, yes there is equipment in the prototype stage of development but it's just too costly for anyone, and no unless government allows genetic manipulation (which they won't as it's completely wrong) then you won't have super uber-space marines.
Thanks for reading.