c-Met receptor tyrosine kinase (RTK) activity has been implicated in establishing the oncogenic phenotype across several human cancers with high levels of the activating c-Met ligand, hepatocyte growth factor (HGF). Malignant plasma cells secrete HGF-activator (HGFA), which converts HGF to its active form, and high HGF levels are correlated with a poor prognosis in multiple myeloma (MM). Syndecan 1 (CD138) on malignant plasma cells binds HGF and potentiates interleukin-6-induced growth and migration. HGF stimulation of myeloma cells also activates autophosphorylation of c-Met and other critical downstream signaling pathways promoting oncogenesis. Finally, pre-clinical studies have shown that suppression of c-Met signaling with a number of small molecules, including ARQ 197, induced myeloma cell apoptosis. Tevantinib-mediated cytotoxic response was observed at concentrations of less than 5 μM, which are achievable in the clinic. These findings supported the hypothesis that suppression of the HGF/c-Met signaling axis could be a rational strategy against relapsed multiple myeloma.
In this phase II study, the efficacy and safety of ARQ 197, a non-competitive and highly selective inhibitor of the c-Met RTK, is being studied in patients with relapsed multiple myeloma. Primary objectives were to determine the overall response rate (ORR) to single-agent tivantinib in patients with relapsed multiple myeloma who had received one to four prior lines of therapy, and to define the toxicities in this population. ARQ 197 was administered at a starting oral dose of 360 mg twice daily with meals for each day of every 4-week treatment cycle. This dose was selected from prior phase I investigations in solid tumors, and at this dose level, steady-state plasma level sof ARQ-197 were 7 μM. Treatment could continue providing that patients did not experience undue toxicities, or disease progression. Tivantinib is provided through the Cancer Therapy Evaluation Program (CTEP), and this study is supported by CTEP, as well as the M. D. Anderson Cancer Center SPORE in Multiple Myeloma.
A total of 10 patients have been enrolled and treated to date, all of whom were evaluable for toxicity, with 8 evaluable for response based on having completed two treatment cycles. Patients had received from 1–3 prior lines of therapy for their disease, and 7/10 (70%) had presented with International Staging System stage I disease at diagnosis. All patients on study had an ECOG performance status of 1 or better, and received a median of 3.5 cycles of tivantinib (range 1–7). The most common adverse events (AEs) of any grade seen in at least 30% of patients included diarrhea (30%), dizziness (30%), dry eyes (30%), shortness of breath (30%), memory change (30%), myalgias (40%), fatigue (60%), and neutropenia (60%). Serious AEs (SAEs) occurred in 2 patients, including one patient with grade 3 syncope, and another with grade 4 neutropenia and a grade 3 anal fissure. Stable disease (SD) has been seen as the best response in 5/7 (71%) evaluable patients, which was maintained for up to 7 cycles, while the remaining patients showed evidence of disease progression.
Enrollment is continuing to this first study of any c-Met inhibitor in patients with relapsed multiple myeloma to better define the role of single-agent tivantinib in this setting. To date, tivantinib has been tolerated well, and some evidence of activity has been seen, with stable disease in 63% of patients, all of whom were progressing at the time of enrollment. Updated toxicity and efficacy data will be presented at the time of the Annual Meeting. Correlative studies are also underway with the goal of identifying potential predictive biomarkers.
Off Label Use: Tivantinib is being evaluated for patients with relapsed myeloma, but is not yet approved in this setting.
Asterisk with author names denotes non-ASH members.