An early idea for Rambo: Last Blood had Sylvester Stallone's iconic hero fighting a genetically-engineered creature similar to Predator's Yautja. The Rambo franchise started as a rather close adaptation of David Morrell's 1972 novel First Blood, with a beaten-down John Rambo lashing out against the town that rejects him after coming back from the Vietnam War. However, every following installment upped the ante with more clear-cut villains, more extravagant action, and less realistic feats from Stallone's invincible warrior.

https://screenrant.com/rambo-5-early-script-monster-sci-fi-ripoff/