The legend beginsLegendary komiks writer-artist Francisco Coching's best-known work first saw light of day in Liwayway Magazine; its first of many incarnations on the big screen was this, Gerardo 'Gerry' de Leon's homespun folksy Pedro Penduko done the same year (if web sources can be trusted).
De Leon is one of the few great filmmakers who dabbled in comics (others include--off the top of my head--Robert Altman, Mario Bava, Lino Brocka, Celso Ad. Castillo (who did a remake starring Ramon Zamora in 1973), Ishmael Bernal, Lamberto Avellana). The previous year de Leon had also adapted Mars Ravelo's Dyesebel, and while I generally agree with Martin Scorsese's jab at the Marvel Cinematic Universe I do think some comic-book adaptations are cinema--you just have to decide which.