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Q&A: What's The Opportunity For ArQule's Reversible BTK Inhibitor ARQ531?

|About: ArQule, Inc. (ARQL)

Fastest path to market is C841s mutant patients (blockbuster opportunity).

Patients intolerant to ibrutinib will be a significant niche, given how many discontinue treatment due to adverse effects.

Richter Transformation is a highly intriguing indication, but promising data here comes with caveat for small N.

$1B market cap for ARQL is cheap to reasonable, considering it's operating in the lucrative targeted oncology space and has a clear path to approval finish line.

Other competitors will be presenting in the near to medium term, including Sunesis Pharmaceuticals' vecabrutinib and Eli Lilly's LOXO-305.

In ROTY's Live Chat one member asked about the market potential for ARQ531, a unique BTK asset which inhibits both wild type and C481S-mutant BTK.

My response, in brief, is the following:

1) Fastest path to market is C481S-mutant patients (poor prognosis, limited treatment options). This is a blockbuster opportunity in and of itself considering that 85% of CLL patients refractory to ibrutinib developed this mutation. For frame of reference, 20,000 CLL patients were diagnosed in the US in 2017. Also, consider that Imbruvica/ibrutinib did $4.1 billion in 2018 US sales. Peak sales estimates imply over $9 billion in sales for Imbruvica by 2024. 

AbbVie has ambitious plans for ibrutinib label expansion

2) ARQ531 should also find its niche in patients who are intolerant to ibrutinib (somewhere between 19% to 41% of patients discontinue treatment due to adverse events).

3) Richter's Transformation (hard to gauge so far as only one patient, who was a partial responder), which has a dire prognosis (median survival is between five and eight months). 500 patients are diagnosed annually in the US with RT.

4) NHL (DLBCL, MCL, FL, WM, MZL)- Very crowded sandbox but data in expansion cohorts here should be interesting. Ibrutinib is already approved for MCL, WM and MZL.

BTK Landscape, courtesty of Sunesis Pharmaceuticals presentation

Just my two cents here, but hope it helps provide perspective going into ASH data update (where durability will be key focus). Look forward to hearing if any other small oncology names on your radar.


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Disclosure: I am/we are long ARQL.