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Comrades who share the same goal of carving out a career path cooperate with each other.
Literal
Course [object-を] pioneer [called-という] same goal [object-を] held comrade-each-other [subject-が] cooperate.
Formal/aspirational register. 進路 can mean 'course' both in the literal sense (direction, path) and figuratively for a career/life direction — here clearly the latter. 開拓する 'to pioneer, develop, break new ground' is a formal verb for opening up new territory (literal or metaphorical). ~同士 'among themselves, fellow, each other' is a suffix marking mutual relationships between people sharing a category. 持った is the past form of 持つ 'to have,' here as a relative clause modifier.