So after researching this subject more thoroughly, I came across this very comprehensive article here which quotes the above cited Rav Moshe but also brings other sources that say otherwise (hence the separate answer post). Again, it does not discuss the part of your question that asks about carrying out clinical trials but I would potentially argue that we have an obligation to save a life when we can at the first opportunity.
To quote the main headlines:
The author notes firstly the need to assess how much risk is involved and the resultant treatment.
The Mishnat Chachamim (cited in Teshuvot Achiezer 2:16:6) asserts that one is permitted to risk Chayei Shaah only if the risk to Chayei Shaah is fifty percent or less (Safek HaShakul). According to this view, one who is expected to live only for a short while is forbidden to engage in a medical procedure if there is a chance greater than fifty percent that the medical procedure might kill him immediately, even though there is a chance that the procedure might completely heal him. The Chatam Sofer (Teshuvot Y.D. 76, cited in the Pitchei Teshuva Y.D. 155:1) seems to agree with this ruling. Rav Chaim Ozer Grodzinsky (Teshuvot Achiezer ad. loc.), however, disagrees and permits a patient to assume an even greater risk than fifty percent in the hope to achieve a longer life.
This view of the Mishnas Chachomim is also supported by Rav Eliezer Waldenberg in his Teshuvos Tzitz Eliezer (10:25:5:5)
He then mentions the Rav Moshe cited above that one may take the risk but then writes however, that Rav Moshe wrote elsewhere in Igros Moshe, Yoreh Deah 3:36 that he is more inclined to the opinion of the Mishnas Chachamim, concluding that we cannot protest if one wishes to rely upon the ruling of Rav Chaim Ozer and assume a very great risk to Chayei Shaah.