Citations

Purpose There are few effective therapies for pancreatic neuroendocrine tumors (PNETs). Recent placebo-controlled phase III trials of the mammalian target of rapamycin (mTOR) inhibitor everolimus and the vascular endothelial growth factor (VEGF)/platelet-derived growth factor receptor inhibitor sunitinib have noted improved progression-free survival (PFS). Preclinical studies have suggested enhanced antitumor effects with combined mTOR and VEGF pathway–targeted therapy. We conducted a clinical trial to evaluate combination therapy against these targets in PNETs. Patients and Methods We conducted a two-stage single-arm phase II trial of the mTOR inhibitor temsirolimus 25 mg intravenously (IV) once per week and the VEGF-A monoclonal antibody bevacizumab 10 mg/kg IV once every 2 weeks in patients with well or moderately differentiated PNETs and progressive disease by RECIST within 7 months of study entry. Coprimary end points were tumor response rate and 6-month PFS. Results A total of 58 patients were enrolled, and 56 patients were eligible for response assessment. Confirmed response rate (RR) was 41% (23 of 56 patients). PFS at 6 months was 79% (44 of 56). Median PFS was 13.2 months (95% CI, 11.2 to 16.6). Median overall survival was 34 months (95% CI, 27.1 to not reached). For evaluable patients, the most common grade 3 to 4 adverse events attributed to therapy were hypertension (21%), fatigue (16%), lymphopenia (14%), and hyperglycemia (14%). Conclusion The combination of temsirolimus and bevacizumab had substantial activity and reasonable tolerability in a multicenter phase II trial, with RR of 41%, well in excess of single targeted agents in patients with progressive PNETs. Six-month PFS was a notable 79% in a population of patients with disease progression by RECIST criteria within 7 months of study entry. On the basis of this trial, continued evaluation of combination mTOR and VEGF pathway inhibitors is warranted.

Abstract Purpose: To determine the MTD, dose-limiting toxicities (DLT), pharmacokinetics, and biologic effects of cixutumumab administered in combination with temsirolimus to children with refractory solid tumors. Experimental Design: Cixutumumab and temsirolimus were administered intravenously once every 7 days in 28-day cycles. Pharmacokinetic and biology studies, including assessment of mTOR downstream targets in peripheral blood mononuclear cells, were performed during the first cycle. Results: Thirty-nine patients, median age 11.8 years (range, 1–21.5), with recurrent solid or central nervous system tumors were enrolled, of whom 33 were fully assessable for toxicity. There were four dose levels, which included two dose reductions and a subsequent intermediated dose escalation: (i) IMC-A12 6 mg/kg, temsirolimus 15 mg/m2; (ii) IMC-A12 6 mg/kg, temsirolimus 10 mg/m2; (iii) IMC-A12 4 mg/kg, temsirolimus 8 mg/m2; and (iv) IMC-A12 6 mg/kg, temsirolimus 8 mg/m2. Mucositis was the predominant DLT. Other DLTs included hypercholesterolemia, fatigue, thrombocytopenia, and increased alanine aminotransferase. Target inhibition (decreased S6K1 and PAkt) in peripheral blood mononuclear cells was noted at all dose levels. Marked interpatient variability in temsirolimus pharmacokinetic parameters was noted. At 8 mg/m2, the median temsirolimus AUC was 2,946 ng • h/mL (range, 937–5,536) with a median sirolimus AUC of 767 ng • h/mL (range, 245–3,675). Conclusions: The recommended pediatric phase II doses for the combination of cixutumumab and temsirolimus are 6 mg/kg and 8 mg/m2, respectively. Clin Cancer Res; 21(7); 1558–65. ©2014 AACR.

Abstract 4-1BB, a member of the TNFR superfamily, is a costimulatory receptor primarily expressed on activated T cells. It has been shown that the administration of agonistic anti-4-1BB Abs enhances tumor immunity and allogenic immune responses. Paradoxically, we found that the administration of an agonistic anti-4-1BB mAb (2A) dramatically reduced the incidence and severity of experimental autoimmune encephalomyelitis (EAE). Adoptive transfer of T cells from such treated mice failed to induce EAE, whereas anti-4-1BB treatment following adoptive transfer of encephalitogenic T cells did not prevent EAE pathogenesis. These results suggest that anti-4-1BB treatment during the induction phase inhibits autoreactive T cell immune responses rather than preventing T cell trafficking into the CNS. This was substantiated by the observations that draining lymph node cells from anti-4-1BB-treated mice failed to respond to Ag stimulation in vitro. In addition, we found that such treatment initially promotes the activation and proliferation of Ag-specific CD4+ T cells but subsequently increases their probability of undergoing activation-induced cell death, thereby inhibiting effector T cell responses. More importantly, 2A treatment also inhibits the relapse of EAE in a clinically relevant murine model of multiple sclerosis. This study indicates that the agonistic Ab against 4-1BB can potentially be used as a novel immunotherapeutic agent for treating autoimmune diseases.

Purpose A phase I/II study of cixutumumab (IMC-A12) in children with refractory solid tumors was conducted. This study was designed to assess the toxicities, pharmacokinetics, and pharmacodynamics of cixutumumab in children to determine a recommended phase II dose and to assess antitumor activity in Ewing sarcoma (ES). Patients and Methods Pediatric patients with relapsed or refractory solid tumors were treated with cixutumumab as a 1-hour intravenous infusion once per week. Two dose levels—6 and 9 mg/kg—were evaluated using a standard three-plus-three cohort design. Patients with refractory ES were treated in an expanded phase II cohort at each dose level. Results Forty-seven eligible patients with a median age of 15 years (range, 4 to 28 years) were enrolled. Twelve patients were treated in the dose-finding phase. Hematologic and nonhematologic toxicities were generally mild and infrequent. Dose-limiting toxicities included grade 4 thrombocytopenia at 6 mg/kg and grade 3 dehydration at 9 mg/kg. Mean trough concentration (± standard deviation) at 9 mg/kg was 106 ± 57 μg/mL, which exceeded the effective trough concentration of 60 μg/mL observed in xenograft models. Three patients with ES had confirmed partial responses: one of 10 at 6 mg/kg and two of 20 at 9 mg/kg. Serum insulin-like growth factor I (IGF-I) levels consistently increased after one dose of cixutumumab. Tumor IGF-I receptor expression by immunohistochemistry did not correlate with response in patients with ES. Conclusion Cixutumumab is well tolerated in children with refractory solid tumors. The recommended phase II dose is 9 mg/kg. Limited single-agent activity of cixutumumab was seen in ES.

Purpose We conducted a pediatric phase I trial of the vascular endothelial growth factor (VEGF)–neutralizing antibody bevacizumab (BV). Primary aims included estimating the maximum-tolerated dose (MTD) and determining the dose-limiting toxicities (DLTs), pharmacokinetics, and biologic effects of BV in children with cancer. Patients and Methods BV (5, 10, 15 mg/kg) was administered intravenously every 2 weeks in 28-day courses to children with refractory solid tumors. Results Twenty-one patients enrolled, 20 (median age, 13 years) were eligible, and 18 completed one course and were fully assessable for toxicity. A total of 67 courses were administered (median, three courses per patient; range, one to 16 courses). Treatment was well tolerated with no DLTs observed. Non-DLTs included infusional reaction, rash, mucositis, proteinuria, and lymphopenia. Increases in systolic and diastolic blood pressure not meeting Common Terminology Criteria for Adverse Events (CTCAEv3) pediatric-specific criteria for hypertension were observed. There was no hemorrhage or thrombosis. Growth perturbation was not detected in a limited sample over the first course. The serum exposure to BV as measured by area under the concentration-time curve (AUC) seemed to increase in proportion to dose. The median clearance of BV was 4.1 mL/d/kg (range, 3.1 to 15.5 mL/d/kg), and the median half-life was 11.8 days (range, 4.4 to 14.6 days). No objective responses were observed. Exploratory analyses on circulating endothelial mobilization and viability are consistent with the available adult data. Conclusion BV is well tolerated in children. Phase II pediatric studies of BV in combination with chemotherapy in dosing schedules similar to adults are planned.