Aquinox Pharmaceuticals (Canada), Inc.

PI3K signaling is a common feature of B-cell neoplasms, including chronic lymphocytic leukemia (CLL) and diffuse large B-cell lymphoma (DLBCL), and PI3K inhibitors have been introduced into the clinic. However, there remains a clear need to develop new strategies to target PI3K signaling. PI3K activity is countered by Src homology domain 2-containing inositol-5′-phosphatase 1 (SHIP1) and, here, we have characterized the activity of a novel SHIP1 activator, AQX-435, in preclinical models of B-cell malignancies.

In vitro activity of AQX-435 was evaluated using primary CLL cells and DLBCL-derived cell lines. In vivo activity of AQX-435, alone or in combination with the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib, was assessed using DLBCL cell line and patient-derived xenograft models.

Pharmacologic activation of SHIP1 using AQX-435 was sufficient to inhibit anti–IgM-induced PI3K-mediated signaling, including induction of AKT phosphorylation and MYC expression, without effects on upstream SYK phosphorylation. AQX-435 also cooperated with the BTK inhibitor ibrutinib to enhance inhibition of anti–IgM-induced AKT phosphorylation. AQX-435 induced caspase-dependent apoptosis of CLL cells preferentially as compared with normal B cells, and overcame in vitro survival-promoting effects of microenvironmental stimuli. Finally, AQX-435 reduced AKT phosphorylation and growth of DLBCL in vivo and cooperated with ibrutinib for tumor growth inhibition.

Our results using AQX-435 demonstrate that SHIP1 activation may be an effective novel therapeutic strategy for treatment of B-cell neoplasms, alone or in combination with ibrutinib.

In this 6-week, randomized, double-blind, placebo controlled, multicenter trial we assessed the effect of the novel SHIP1 (SH2-containing inositol-5'-phosphatase 1) activator AQX-1125 on bladder pain and urinary symptoms in patients with interstitial cystitis/bladder pain syndrome.

Women with interstitial cystitis/bladder pain syndrome and a mean pain score of 5 or greater on an 11-point scale despite treatment were randomized to AQX-1125 or placebo orally once daily for 6 weeks. Average and maximum pain scores (daily) and urinary frequency (before visits) were recorded by e-diary and at clinic visits. The O'Leary-Sant ICSI (Interstitial Cystitis Symptom Index) and ICPI (Interstitial Cystitis Problem Index), BPIC-SS (Bladder Pain Interstitial Cystitis Symptom Score) and SF-12v2® questionnaires were administered. Safety was monitored through 6 weeks of treatment and 4 weeks of followup.

A total of 37 patients received oral AQX-1125 and 32 received placebo. At 6 weeks average daily pain on an e-diary decreased by 2.4 points for AQX-1125 vs 1.4 for placebo (p = 0.061), while average pain at clinic decreased by 2.6 vs 1.1 (p = 0.008), maximum daily pain on e-diary diary decreased by 2.6 vs 1.4 (p = 0.030) and maximum pain at clinic decreased by 2.8 vs 1.1 (p = 0.028). AQX-1125 reduced ICSI by 3.8 points vs 1.4 for placebo (p = 0.005), ICPI by 3.6 points vs 1.6 (p = 0.014) and BPIC-SS by 8.8 points vs 4.0 (p = 0.011). Urinary frequency decreased on AQX-1125 by 3.6 voids per 24 hours vs 0.8 for placebo (p = 0.040). Adverse event rates were similar for AQX-1125 and placebo (51.4% and 78.1%, respectively). No serious adverse events were reported.

Women with moderate to severe interstitial cystitis/bladder pain syndrome who were treated with the oral SHIP1 activator AQX-1125 reported significantly reduced bladder pain and improved urinary symptoms at 6 weeks. AQX-1125 was well tolerated. AQX-1125 may be a potential new treatment for interstitial cystitis/bladder pain syndrome. It warrants further investigation.