MABp1 to improve clinical outcomes of patients with symptomatic refractory metastatic colorectal cancer patients: Per-protocol population analysis of phase III study (PT026).

Abstract

3530 Background: Refractory metastatic colorectal cancer (mCRC) patients derive minimal benefit from further exposure to toxic agents. MABp1 is an anti-interleukin 1 alpha antibody that is shown to prolong survival (NCT01767857) and improves outcomes when assessed with a primary endpoint based on a constellation of objective and patient self-reported measures (NCT02138422) (Hickish T. et al Lancet Oncology 2017). In the latter study, clinically advanced patients were enrolled (symptomatic, ECOG 1,2), and 18% of patients progressed prior to reaching the endpoint assessments. Here we present the outcomes in per-protocol population (PP), those patients completing week 8 assessments. Methods: 309 patients randomized 2:1 to receive MABp1 versus placebo. Patients were ECOG 1-2, with mCRC refractory to chemotherapy, any degree of weight loss, and cancer-associated symptoms. The composite primary endpoint assessed the rate of patients achieving stabilization or improvement in lean body mass (LBM) and two of three symptom measures (pain, fatigue, appetite loss) from screening to the week 8 assessment. The study was designed for placebo cross-over, thus OS analysis for MABp1 vs placebo was not possible. Results: 57 patients (38 MABp1 [18%] and 19 placebo [19%]) discontinued study prior to the week 8 assessment due to disease progression, including 17 (8%) and 11 (11%) deaths in MABp1 and placebo respectively. 62% of placebo patients received MABp1 after 8 weeks. 252 patients, 40% in MABp1 (68/169) vs 23% in placebo (19/83) met the primary endpoint (p = 0.003). 139 patients were available for PP survival analysis (90 MABp1 vs 49 Placebo). Median OS of those achieving the primary endpoint was 11.7 months vs 5.7 months for those that did not (HR 0.39; p < 0.0001). Radiographic stable disease was improved (42% vs 12%; p < 0.001) and incidence of SAEs (6% vs 15%; p = 0.11) reduced in those achieving the primary endpoint. Conclusions: Achieving the primary endpoint was associated with improvement in outcomes, RECIST stabilization, SAEs and survival. Further study should confirm the effect of MABp1 on survival in this population. Clinical trial information: NCT02138422.