The clinical effect of the dual-targeting strategy involving PI3K/AKT/mTOR and RAS/MEK/ERK pathways in patients with advanced cancer.

PURPOSE: This study evaluated the clinical relevance of the dual-targeting strategy involving PI3K/AKT/mTOR and RAF/MEK/ERK pathways. EXPERIMENTAL DESIGN: We investigated safety, efficacy, and correlations between tumor genetic alterations and clinical benefit in 236 patients with advanced cancers treated with phase I study drugs targeting phosphoinositide 3-kinase (PI3K) and/or mitogen-activated protein kinase (MAPK) pathways in our Phase I Clinical Trials Program. RESULTS: Seventy-six (32.2%) patients received a PI3K pathway inhibitor in combination with a MAPK pathway inhibitor (D), whereas 124 (52.5%) and 36 (15.3%), respectively, received an inhibitor of either the PI3K or MAPK pathways (S). The rates of drug-related grade >III adverse events were 18.1% for (S) and 53.9% for (D; P < 0.001); the rates of dose-limiting toxicities were 9.4% for (S) and 18.4% for (D; P = 0.06). The most frequent grade >III adverse events were transaminase elevations, skin rash, and mucositis. In our comprehensive tumor genomic analysis, of 9 patients who harbored coactivation of both pathways (colorectal cancer, n = 7; melanoma, n = 2), all 5 patients treated with (D) had tumor regression ranging from 2% to 64%. CONCLUSIONS: These results suggest that dual inhibition of both pathways may potentially exhibit favorable efficacy compared with inhibition of either pathway, at the expense of greater toxicity. Furthermore, this parallel pathway targeting strategy may be especially important in patients with coexisting PI3K pathway genetic alterations and KRAS or BRAF mutations and suggests that molecular profiling and matching patients with combinations of these targeted drugs will need to be investigated in depth.

Preclinical antitumor activity and pharmacokinetics of methyl-2-benzimidazolecarbamate (FB642).

Methyl-2-benzimidazolecarbamate (carbendazim, FB642) is an anticancer agent that induces apoptosis of cancer cells. In vitro, FB642 demonstrated potent antitumor activity against both the murine B16 melanoma (IC50 = 8.5 microm) and human HT-29 colon carcinoma (IC50 = 9.5 microm) cell lines. FB642 was also highly active against both murine tumor models and human tumor xenografts at varying doses and schedules. In the murine B16 melanoma model, T/C values > 200 were observed. In the human tumor xenograft, FB642 produced tumor growth inhibition of greater than 58% in five of the seven xenograft models evaluated. Partial and complete tumor shrinkage was noted with FB642 against the MCF-7 breast tumor model. Pharmacokinetic studies in rats demonstrated that oral absorption of FB642 was variable and may be saturated at the 2000 mg/kg dose level since higher doses failed to produce a further increase in the area under the time concentration curve. Toxicity of FB642 in vivo appeared to be dose-dependent. Lower doses in the range of 2,000-3,000 mg/kg were better tolerated, while still preserving antitumor activity. Evaluation of FB642 in phase I clinical trials of adult patients with advanced malignancies is currently ongoing.