Insmed is looking to expand the role of its inhaled Mycobacterium avium complex (MAC) lung disease therapy, Arikayce (amikacin), following the drug’s success in a Phase IIIb trial.
In the ENCORE study (NCT04677569), the antibiotic plus a multidrug combination of azithromycin and ethambutol significantly improved the baseline change in respiratory symptom scores over the placebo-multidrug at month 13 – meeting the trial’s primary endpoint.
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Alongside its impact on respiratory symptoms, Arikayce also triggered a culture conversion rate of 82.4% at 13 months, compared with 55.6% in the placebo arm. This means that significantly more patients given Arikayce over placebo tested negative for MAC bacteria following treatment.
Arikayce’s safety profile was generally consistent with previous studies of the drug, though 32% of patients did experience at least one severe treatment-emergent adverse event (TEAE) in the study. The TEAE-prompted discontinuation rate was 31% and 18% in the Arikayce and placebo treatment arms, respectively.
The global ENCORE study enrolled 425 patients across 258 sites with MAC lung infections. None of the patients had previously received treatment with antibiotics for this particular infection.
Arikayce is an inhaled antibiotic therapy designed to kill bacteria by both disrupting the cell membrane and stopping protein production. Unlike traditional oral antibiotics used for MAC lung infections like azithromycin and ethambutol, Arikayce is delivered directly to the lungs via liposomes, which Insmed says can enhance the uptake of the drug into locations where MAC bacteria reside.
Insmed seeks approval for Arikayce in earlier lines
Following the positive results of this study in frontline MAC, Insmed is now eyeing a label expansion for Arikayce in both the US and Japan. The biopharma company plans to submit a supplemental new drug application (sNDA) to American and Japanese regulators in H2 2026.
Insmed first secured provisional approval for Arikayce in 2018, which saw it become available in combination with multidrug therapy for patients with limited or no alternative treatment options. Physicians generally prescribed the drug to patients who still tested positive for MAC lung disease after at least six months of treatment with a multidrug treatment regimen.
If approved, Insmed’s CMO, Martina Flammer, noted that patients with a new MAC infection could see “benefit with Arikayce earlier in their treatment journey”, which could improve outcomes in this population.
William Blair analyst Matt Phipps echoed this sentiment, noting that he expects the ENCORE results to allow Insmed to secure regulatory approval for Arikayce in MAC all-comers. William Blair expects Arikayce to launch in this population in 2027.
Jefferies analysts also had a positive outlook on the results, as they could “meaningfully expand” Arikayce’s total addressable market from its current accelerated approval in refractory MAC lung disease.
GlobalData, parent company of Clinical Trials Arena, forecasts that Arikayce will become a blockbuster seller for Insmed, generating $1.3bn in sales in 2031 at the end of the current forecast period.
