After I tried to focus attention on the Silence Therapeutics presentation this afternoon at the BIO CEO & Investor Conference, as soon as I had published my earlier blog I half regretted my decision to do so because more often than not positive news does not materialize when you expect it. This blog in particular is littered with such speculations. Fortunately, this time was different as Silence Therapeutics was able to present some really neat data from the ongoing phase I study with Atu-027 in the treatment of advanced solid cancer.
To date, at least 20 patients have received at least one Atu027 siRNA-lipoplex infusion. While the dose escalation is being conducted in a very cautious manner, i.e. slowly, dosages are now approaching levels of around 0.1mg/kg where therapeutic efficacy may be expected based on pre-clinical non-human primate data. Importantly, after 157 infusions administered, the drug seems to be very well tolerated. The only notable safety concern may be the complement activation likely related to the positive charge of Silence’s lipoplex formulation and that the Company characterized to be ‘limited’ and ‘transient’ in nature. This would be consistent with the fact that no dose limiting toxicity was reported,
There was also anecdotal evidence for anti-tumor efficacy of Atu-027. 5 out of 20 patients experienced stable disease during the 3 month study period with one patient in the sixth cohort (7th dose cohort now dosing) said to exhibit ‘remarkable shrinkage of target and non-target lesions’. There was also a mention of a reduction in lung metastases which could be clinically very meaningful for certain cancers (slide 16). Unfortunately, since this presentation was not webcast live, it is currently difficult for me to figure out the context in which this comment was made.
In sum, from today on, Atu-027 has to be considered one of the foremost RNAi clinical candidates and I look forward to data from the higher dose groups at ASCO. Congrats to the company for having come this far.