The rapamycin analog temsirolimus (CCI-779) is also a noncytotoxic agent which delays tumor proliferation.
Temsirolimus is a prodrug of rapamycin. It is approved by the U.S. Food and Drug Administration (FDA)  and the European Medicines Agency (EMA), for the treatment of renal cell carcinoma (RCC). Temsirolimus has higher water solubility than rapamycin and is therefore administered by intravenous injection.  It was approved on May 30, 2007, by FDA for the treatment of advanced RCC.
Temsirolimus has also been used in a Phase I clinical trial in conjunction with neratinib, a small-molecule irreversible pan-HER tyrosine kinase inhibitor. This study enrolled patients being treated for HER2-amplified breast cancer, HER2-mutant non-small-cell lung cancer, and other advanced solid tumors. While common toxicities included nausea, stomatitis, and anemia; responses were noted.