The present invention provides drug conjugates comprising 5-aminolevulinic acid (ALA), an aldehyde and a carboxylic acid that may function as a histone deacetylase inhibitor (HDACI). These conjugates may serve as co-drugs which release a plurality of active species in vivo. The novel drug conjugates may be used, for the treatment or prevention of cancer in PDT-dependent and/or PDT-independent (nonPDT) treatments, as well as for cosmetic uses. In addition the present invention provides novel uses for both the novel and known compounds. According to some embodiments, the present invention provides drug conjugates (co-drugs) comprising (i) ALA, (ii) an aldehyde and (iii) a carboxylic acid that may function as a histone deacetylase inhibitor (HDACO for the treatment of anemia and/or for the induction of erythropoiesis.
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