The present invention includes a method to reverse the trend towards progressive resistance to consecutive treatments for T-cell lymphoma in a patient. This method includes selecting a patient having T-cell lymphoma, wherein the patient has had at least one prior treatment for T-cell lymphoma, wherein the prior treatment comprises non-10-propargyl-10-deazaaminopterin； and administering to the patient a composition comprising a therapeutically effective amount of 10-propargyl-10-deazaaminopterin, whereby the trend towards progressive resistance is reversed.
