Date: 2016-07-06
Type of information: Presentation of results at a congress
phase: 1
Announcement: presentation of results at the American Society of Clinical Oncology (ASCO) annual meeting, in Chicago
Company: Merrimack Pharmaceuticals (USA - MA)
Product: MM-151
Action
mechanism: monoclonal antibody. MM-151 is a mixture of three fully human monoclonal antibodies designed to bind and inhibit signaling of EGFR. EGFR-mediated signaling promotes the growth and survival of cancer cells and is recognized as an important drug target in several types of cancer, including colon, lung, breast, pancreatic and head and neck cancers. The use of three antibodies maximizes receptor inhibition, and provides mechanisms to overcome resistance to EGFR-targeted therapies. MM-151 is also being evaluated in two other Phase 1 studies; one in combination with the Onyvide® (irinotecan liposome injection) regimen for metastatic CRC, and another in a first-of-its-kind, multi-arm basket study in combination with three other novel agents, two of which are from Merrimack's oncology pipeline. Merrimack initiated these studies in May.
Disease: advanced solid tumors, colorectal cancer, squamous cell head and neck cancer, non small cell lung cancer, triple negative breast cancer
Therapeutic area: Cancer - Oncology
Country: USA
Trial
details: This study is a Phase 1 and pharmacologic open-labeled dose-escalation trial using a "3+3" design, evaluating MM-151 at varying dose levels and frequencies, and subsequently in combination with irinotecan. (NCT01520389)
Latest
news: * On June 6, 2016, Merrimack Pharmaceuticals announced results from the final analysis of the Phase 1 study of MM-151, a novel investigational oligoclonal epidermal growth factor receptor (EGFR) inhibitor, in patients with refractory solid tumors. These results were presented at a Poster Discussion Session at the 2016 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. Data from the Phase 1 study show positive clinical activity across multiple solid tumor types in a heavily pretreated patient population. Twenty-one percent of evaluable patients in the metastatic colorectal cancer (CRC) cohort achieved an objective response and 54 percent of patients showed a decrease in tumor size. A median progression-free survival (PFS) of four months was also observed within the CRC cohort. MM-151 also exhibited positive clinical activity in both EGFR-treatment refractory and EGFR-treatment naïve populations. These preliminary data support the potential for broad clinical effect, and demonstrate an acceptable safety profile consistent with existing EGFR therapies.
Methodology and Results: This study evaluated MM-151 as a monotherapy and in combination with irinotecan. An expansion cohort was enrolled to evaluate clinical activity in EGFR-refractory metastatic CRC patients. Subset analyses and additional biomarker evaluations were performed in EGFR-driven indications. A total of 111 patients were treated with escalating dose levels; 87 patients on monotherapy and 24 patients receiving MM-151 in combination with irinotecan. The most common tumor types were CRC (45 [41%]), head and neck cancers (14 [13%]) and non-small cell lung cancer (11 [10%]).
Safety of MM-151: MM-151 demonstrated a comparable safety profile to approved EGFR inhibitors as a monotherapy and in combination with irinotecan. Apart from infusion reactions, which occurred at decreasing frequency and severity as the dosing schedule was modified over the course of the study, the most common adverse events reported were rash, hypomagnesemia, fatigue and diarrhea in the monotherapy cohorts. These adverse events were expected and consistent with EGFR inhibition class toxicities.
Results: Preliminary indications of clinical activity with MM-151, across both the EGFR-refractory and naïve populations, suggest there is potential for broad effect. Biomarker profiling suggests MM-151 may overcome mechanisms of resistance.
Preliminary data in the CRC subset show 54 percent of evaluable patients had a reduction in tumors. Forty-five percent (13/29) of patients in the CRC subset achieved stable disease or partial response at three cycles of treatment and 17 percent (5/29) achieved a partial response, with highly durable responses and disease control.
Preliminary biomarker analysis of blood samples ("liquid biopsies") following MM-151 treatment show low occurrence of acquired KRAS/NRAS/BRAF mutations in the CRC cohort and no occurrence of acquired EGFR extracellular domain mutations, which have been reported to mediate resistance to cetuximab and panitumumab.
A median PFS of four months was observed in the CRC cohort.
Observations in exploratory biomarker analyses are consistent with the multiple mechanisms of action that have been previously described for MM-151 in preclinical studies, including EGFR downregulation, expression of high-affinity EGFR ligands across indications (including refractory metastatic CRC) and activity in tumors expressing EGFR and downstream mutations. Further clinical evaluation is underway.
