ARQL pleasantly surprised investors yesterday on its quarterly call by giving two positive clinical trial updates. First, and most importantly, the company reported its first results from its highest dosing cohort (65 mg/day) for ARQ 531, its reversible Btk inhibitor in tits ongoing phase 1 trial in certain blood cancers: An impressive 88% tumor volume reduction partial response at the first readout, in a third line CLL patient harboring a C481S mutation who was refractory to an irreversible Btk inhibitor. This is significant because it is the clearest proof of principle to date in a clinical trial that ARQ 531 can be highly effective when given to the right patient (3rd line CLL patient with a C481S mutation-containing tumor that is refractory to an irreversible Btk inhibitor) at the right dose (65 mg/day). Prior results were given at lower doses and to more heavily pre-treated patients, some of whom did not harbor a C481S mutation, and although a number of tumor volume reductions were observed as well as 1 partial response (>50% tumor volume reduction) with earlier cohorts, today's report was the most significant reduction and reported after only 2 months of treatment (first scan) and from the first patient treated at this highest cohort (65 mg) to date.
At a higher level, this result is significant because although irreversible Btk inhibitors such as the multi-billion dollar drug Ibrutinib, are highly effective in a number of blood cancers including CLL, for many patients who can tolerate their side effects, their tumors eventually become resistant, mainly due to the development of a Btk-C481S mutation (See http://ascopubs.org/doi/pdf/10.1200/JCO.2016.70.2282). ARQ 531 is the leading reversible Btk inbhitor in clinical progress thus far, that is effective in inhibiting Btk-C481S mutant kinases, in addition to wild type Btk. Arqule has reported that it expects the annual market to exceed $1 billion for reversible Btk inhibitors used in 2nd and 3rd line settings for patients with certain blood cancers whose tumors are resistant to irreversible Btk inhibitors and harbor a Btk-C481S mutation. Of course, this is only the first patient at this highest dose cohort in this phase 1 trial, and before ARQL can start selling ARQ 531 much more data is needed, including not only data from additional patients at this 5 mg/day dose, but for longer durations, and eventually as part of a successful registrational trial.
Secondly, ARQL announced on its Q4 2018 conference call yesterday, that the FDA has agreed to allow them to perform a registrational trial for its ATK inhibitor, miransertib, not only in patients with the ultra rare disease, Proteus Syndrome, but also in patients with the rare, but much more prevalent, PROS family of rare overgrowth diseases. There are no approved therapies for any of these debilitating disorders currently. Not only does this clinical trial pathway if successful likely provide ARQL a coveted rare pediatric disease voucher (worth over $100 million), but it suggests that annual revenue in the $100s of millions is possible for miransertib in these indications.
In summary, today's update from ARQL first and foremost provides promising news for blood cancer patients such as CLL patients, and patients with the rare diseases, Proteus Syndrome or PROS. For ARQL investors today's report provided greater than a 67% increase in ARQL's share price. We are thrilled that all of our Amp funds, including our hypothetical Core Fund, and our real tracking hedge fund, invested in ARQL ahead of this news based on its prior promising pre-clinical data and the early efficacy signs in its Phase 1 trial.
We look forward to getting another update from Arqule on ARQL 531 this summer. In the meantime, if you were a subscriber to our Amp Core subscription, you would have seen our stake in ARQL as one of our 5-15 companies in our hypothetical Amp Core fund. Sign up for an Amp Core subscription today and see all of our positions in our Amp Core fund, get updates on our Amp Core fund trades, and see catalyst events coming this year, along with our comments on the events, for our Amp Core fund companies as well as numerous other small and mid-cap biopharma companies. You can try risk-free with our 14-day money back guarantee. See https://www.ampbioresearch.com/premium-plan for more details.