- The dose-limiting toxicity (DLT) of CBP501 was rapid onset allergic reaction, as was suggested by preclinical toxicology. Other toxicities were quite limited. No evidence of potentiation of either CBP501 or cisplatin toxicity was found in the combination phase I trial, and the toxicity of the combination, primarily related to cisplatin, is manageable. It is expected that CBP501 and pemetrexed will display non-overlapping toxicity profiles in combination, given that hematological toxicity and gastrointestinal toxicity are the principal toxicity types of the latter.