Masitinib plus gemcitabine as first-line treatment of pancreatic cancer with pain: Results from phase 3 study AB12005.
Authors: Ezenfis Joel , Hermine Olivier ,   AB12005 Study Group
Published: June 2021

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Background: Masitinib (MAS) is a small molecule drug targeting mast cell and macrophage activity, innate immune cells that are critical components of the tumor microenvironment. Proof of concept that MAS in combination with gemcitabine (GEM) improved overall survival (OS) in pancreatic cancer (PC) patients (pts) with pain, was previously shown [doi 10.1093/annonc/mdv133]. The presence of pain in PC is thought to identify pts whose disease is driven in part by a pro-tumoral immune response. Methods: AB12005 was a prospective, placebo (PBO) controlled, double blind, randomized (2:1 MAS:PBO, stratified by disease stage, ECOG and geographic region) phase 3 trial, evaluating oral MAS (6.0 mg/kg/d) in combination with GEM (1000 mg/m²) against PBO plus GEM for the treatment of unresectable locally advanced PC (LAPC) and/or metastatic PC (mPC) pts with pain criteria; i.e. baseline visual analog scale of pain intensity (VAS) > 20 and/or pt treated with an opioid analgesics dose ≥1 mg/kg/d at baseline. Eligible pts were chemo-naïve with histologically or cytologically confirmed inoperable LAPC or mPC and an ECOG status ≤2. The estimated sample size was ̃330 pts to detect an OS hazard ratio (HR) of 0.68 (80% power, 2-sided α = 0.025) after 310 deaths. The study was successful if improvement in median OS (primary endpoint) relative to control reached a 2.5% level of statistical significance for either a targeted subgroup of LAPC with pain criteria, or the overall study cohort. Results: A total of 384 pts were enrolled (safety population n = 383; mITT n = 379; target subgroup n = 92). In the predefined subgroup of unresectable LAPC with pain, MAS-GEM (n = 62) showed significant benefit over PBO-GEM (n = 30) with median OS of 13.0 months (97.5% CI [11.0;18.0]) vs 11.2 months (97.5% CI [7.4;13.0]); p = 0.007. The HR was 0.46 (97.5% CI [0.2;0.9], p = 0.0047), corresponding to a significant 54% reduction in risk of death for MAS-GEM pts relative to control. Secondary analyses in the same subgroup were convergent with this primary outcome. Median PFS showed a 1.8 month between group difference in favor of MAS-GEM (p = 0.039), with a HR of 0.47 (97.5% CI [0.3;0.9], p = 0.014). The 12-month and 18-month OS rates showed a 1.3 fold and 3.4 fold improvement, respectively, in favor of MAS-GEM (53.2% and 33.9% for MAS-GEM vs 40.0% and 10% for PBO-GEM, respectively). In the overall population, comprising LAPC and mPC pts with pain, no survival benefit was observed; median OS for MAS-GEM (n = 244) was 6.9 months vs 8.0 months for PBO-GEM (n = 135); p = 0.461. The MAS-GEM combination was well tolerated with no sign of add-on toxicity. The proportion of patients presenting at least one adverse event (AE) or serious AE was respectively, 96.3% and 19.1% for MAS-GEM (n = 246) vs 99.3% and 21.3% for PBO-GEM (n = 136). Conclusions: The combination MAS (6.0 mg/kg/d) plus GEM may provide a new first line treatment option for unresectable LAPC pts with associated pain. Clinical trial information: NCT03766295.