This suggests some sort of synergism, as erlotinib and docetaxel have rarely been associated with hyponatremia outside situations with a known hyponatremia incidence risk, as incurred by patients with non-small cell lung cancer or patients treated with cisplatin (the erlotinib-combination trial in fact included patients with lung cancer, but hyponatremia occurred exclusively in patients administered the HSP90 inhibitor at high dose [12]). The gene discussed is HSP90AA1; the disease is non-small cell lung carcinoma.