Bellus is expected to report Phase 1 data, which will include taste, sometime in late November – early December. Below we analyze Merck’s Phase 2b data for their P2X3 candidate to set expectations for Bellus’ readout.
Merck’s Most Effective Dose Burdened With Troubling Taste Effects
Merck’s Phase 2b data showed that the 50mg dose was the only dose to show statistically significant cough frequency reduction from baseline compared to placebo. The other two doses (7.5 & 20mg) did not show a statistically significance cough reduction from placebo.
As seen below, the most common taste adverse events occurred in patients taking the 50mg dose. Taste alteration events were reported in 47.6% of cases on the 50mg dose, reduced ability to taste on 23.8% and loss of taste on 20.6%.
Adverse events related to taste were observed in 81% of patients on the 50mg dose. These patients who observed a taste effect were given a Patient Reported Outcome (PRO) questionnaire to determine how bothersome the taste effect was. Roughly 40% of the patients reported the taste effect was “very or extremely bothersome”.
Expectations: Bellus Must Cut Taste Effects by At Least Half of What Merck Has Shown
In their upcoming Phase 1, Bellus will report safety, tolerability and effect on taste at different doses in 90 healthy patients. The single ascending dose will enroll 60 patients and multiple ascending dose will enroll an additional 30 patients.
At the dose selected to advance into Phase 2, we believe Bellus has to show at least half the taste effect of Merck to be considered a clinically significant improvement. For example, 40% of patients (or lower) must report an adverse taste effect of any kind (compared to 81% for Merck).
We believe Bellus’ Phase 1 will follow the same protocol as Merck. This means a direct comparison between taste data sets can be made when Phase 1 is announced. Bellus will report hypogeusia, dysgeusia and ageusia adverse events as well as the proportion of patients with taste effects. These patients will also complete a PRO questionnaire to determine how bothersome the taste effect is.
P2X3 Drug Class Remains Superior after Recent Competitor Failures
In October, two candidates in competing cough drug classes were discontinued, validating P2X3 drugs as the most effective treatment options. Menlo’s NK-1 candidate failed to outperform placebo (read more here). In September, GlaxoSmithKline’s TRPV4 candidate was also discontinued in September due to lack of efficacy in chronic cough.
Bellus is Worth At Least $1.25 if Phase 1 Data is Positive
We believe Phase 1 data is a low hurdle and remain confident in Bellus’ ability to post positive data (read why here). With upside of 90%, we think Bellus is attractive at these levels.
PropThink contributors are LONG BLUSF
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