Evaluation of the Effect of Lorlatinib on CYP2B6, CYP2C9, UGT, and P-Glycoprotein Substrates in Patients with Advanced Non-Small Cell Lung Cancer.

BACKGROUND AND OBJECTIVE: Lorlatinib is a tyrosine kinase inhibitor approved for the treatment of advanced anaplastic lymphoma kinase-positive non-small cell lung cancer. This study assessed the effect of steady-state lorlatinib on the metabolic enzymes cytochrome P450 (CYP) 2B6, CYP2C9, and uridine 5'-diphospho-glucuronosyltransferase (UGT) and the P-glycoprotein (P-gp) transporter. METHODS: Thirty-two patients received a single oral dose of a probe drug on Day - 2 to determine the pharmacokinetics of the probe drug alone. Starting on Day 1, patients received 100 mg oral lorlatinib daily. On Day 15, a single oral dose of the probe drug was administered concurrently with lorlatinib. Pharmacokinetic parameters for these probe substrates were assessed. RESULTS: Plasma exposures of all probe substrates were reduced by lorlatinib compared with the probe alone. The greatest reduction in area under the plasma concentration-time curve from time zero to infinity (AUC∞) and maximum (peak) plasma drug concentration (Cmax) (67% and 63% decrease, respectively) was observed with the P-gp probe substrate fexofenadine. Lorlatinib coadministration also decreased the AUC∞ and Cmax of bupropion (CYP2B6 probe substrate) by 25% and 27%, tolbutamide (CYP2C9 probe substrate) by 43% and 15%, and acetaminophen (UGT probe substrate) by 45% and 28%, respectively. CONCLUSIONS: Lorlatinib is a net moderate inducer of P-gp and a weak inducer of CYP2B6, CYP2C9, and UGT after steady state is achieved with daily dosing. Medications that are P-gp substrates with a narrow therapeutic window should be avoided in patients taking lorlatinib; no dose modifications are needed with substrates of CYP2B6, CYP2C9, or UGT. CLINICALTRIALS: gov: NCT01970865.

Lorlatinib Exposure-Response Analyses for Safety and Efficacy in a Phase I/II Trial to Support Benefit-Risk Assessment in Non-Small Cell Lung Cancer.

Lorlatinib is a small molecule inhibitor of anaplastic lymphoma kinase (ALK) and c-ROS oncogene 1 (ROS1) tyrosine kinases and is approved for the treatment of patients with ALK-positive advanced non-small cell lung cancer (NSCLC). In the phase I/II study (NCT01970865), potential exposure-response (E-R) relationships between lorlatinib and selected safety and efficacy end points were evaluated in patients with NSCLC. E-R relationships were assessed for safety end points with incidence > 10% in all treated patients (n = 328). In total, 4 safety end points were assessed: hypercholesterolemia grade ≥ 3, hypertriglyceridemia grade ≥ 3, weight gain grade ≥ 2, and treatment-emergent adverse events (TEAEs) grade ≥ 3. Using logistic regression, significant relationships were identified between lorlatinib plasma exposure and risk of hypercholesterolemia grade ≥ 3 (odds ratio (OR) 5.256) and risk of TEAE grade ≥ 3 (OR 3.214). The covariates baseline cholesterol and time on study prior to the event (TE) were associated with the probability of hypercholesterolemia grade ≥ 3. Baseline cholesterol and TE were found to have a statistically significant correlation with TEAE grade ≥ 3. Exposure-efficacy relationships were assessed for objective response rate (ORR; n = 197) and intracranial objective response rate (IC-ORR; n = 132). Lorlatinib plasma exposure was not identified as a statistically significant factor related to either efficacy end point. The only significant E-R relationships identified for efficacy were between baseline alkaline phosphatase and baseline amylase with IC-ORR (ORs 0.363 and 1.015, respectively). These findings support the lorlatinib indicated dose and dose modification guidelines regarding the management of lorlatinib-related AEs.

Impact of lorlatinib on patient-reported outcomes in patients with advanced ALK-positive or ROS1-positive non-small cell lung cancer.

OBJECTIVES: To evaluate patient-reported outcomes (PROs) from a phase 1/2 study (NCT01970865) in patients with anaplastic lymphoma kinase (ALK)- or ROS1-positive advanced non-small cell lung cancer (NSCLC) treated with lorlatinib 100 mg once daily. MATERIALS AND METHODS: PRO measures, including global quality of life (QoL), functioning domains and symptoms, were assessed by the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30 (QLQ-C30) and the 13-item Lung Cancer (QLQ-LC13) module. Mean changes of absolute scores from baseline were assessed. Percentages of patients showing improvement, stability or worsening on each scale were reported, with a change of ≥10 points considered clinically meaningful (CM). RESULTS: 255 patients completed baseline and ≥1 post-baseline PRO assessment. Most patients had CM improvement (42.4 %) or stable (38.0 %) scores for global QoL. Functioning domains with the greatest proportion of patients with improved scores were role (37.6 %) and emotional (36.9 %); only one domain had more patients showing worsening than improving function (cognitive [24.3 % vs 22.4 %]). Most patients showed improved or stable scores for disease-related symptoms. No QLQ-C30 symptom domains had more patients worsening than improving. Symptoms on the QLQ-C30 scale with the greatest proportion of patients with improved scores were fatigue (49.4 %) and insomnia (46.3 %). Four QLQ-LC13 domains had more patients worsening than improving (two most affected were peripheral neuropathy [37.3 % vs 13.7 %] and alopecia [19.2 % vs 13.3 %]). Symptoms on the QLQ-LC13 scale with the greatest proportion of patients with improved scores were cough (42.7 %) and pain in other parts (32.9 %). CONCLUSIONS: Lorlatinib treatment showed CM improvement from baseline in global QOL that was maintained over time. Additionally, there were improvements in physical, emotional, social, and role functioning. Improvements were shown in appetite loss and key symptoms such as pain, dyspnea, cough and fatigue; a worsening in peripheral neuropathy was noted.

Lorlatinib in advanced ROS1-positive non-small-cell lung cancer: a multicentre, open-label, single-arm, phase 1-2 trial.

BACKGROUND: Lorlatinib is a potent, brain-penetrant, third-generation tyrosine kinase inhibitor (TKI) that targets ALK and ROS1 with preclinical activity against most known resistance mutations in ALK and ROS1. We investigated the antitumour activity and safety of lorlatinib in advanced, ROS1-positive non-small-cell lung cancer (NSCLC). METHODS: In this open-label, single-arm, phase 1-2 trial, we enrolled patients (aged ≥18 years) with histologically or cytologically confirmed advanced ROS1-positive NSCLC, with or without CNS metastases, with an Eastern Cooperative Oncology Group performance status of 2 or less (≤1 for phase 1 only) from 28 hospitals in 12 countries worldwide. Lorlatinib 100 mg once daily (escalating doses of 10 mg once daily to 100 mg twice daily in phase 1 only) was given orally in continuous 21-day cycles until investigator-determined disease progression, unacceptable toxicity, withdrawal of consent, or death. The primary endpoint was overall and intracranial tumour response, assessed by independent central review. Activity endpoints were assessed in patients who received at least one dose of lorlatinib. This study is ongoing and is registered with ClinicalTrials.gov, NCT01970865. FINDINGS: Between Jan 22, 2014, and Oct 2, 2016, we assessed 364 patients, of whom 69 with ROS1-positive NSCLC were enrolled. 21 (30%) of 69 patients were TKI-naive, 40 (58%) had previously received crizotinib as their only TKI, and eight (12%) had previously received one non-crizotinib ROS1 TKI or two or more ROS1 TKIs. The estimated median duration of follow-up for response was 21·1 months (IQR 15·2-30·3). 13 (62%; 95% CI 38-82) of 21 TKI-naive patients and 14 (35%; 21-52) of 40 patients previously treated with crizotinib as their only TKI had an objective response. Intracranial responses were achieved in seven (64%; 95% CI 31-89) of 11 TKI-naive patients and 12 (50%; 29-71) of 24 previous crizotinib-only patients. The most common grade 3-4 treatment-related adverse events were hypertriglyceridaemia (13 [19%] of 69 patients) and hypercholesterolaemia (ten [14%]). Serious treatment-related adverse events occurred in five (7%) of 69 patients. No treatment-related deaths were reported. INTERPRETATION: Lorlatinib showed clinical activity in patients with advanced ROS1-positive NSCLC, including those with CNS metastases and those previously treated with crizotinib. Because crizotinib-refractory patients have few treatment options, lorlatinib could represent an important next-line targeted agent. FUNDING: Pfizer.

ALK Resistance Mutations and Efficacy of Lorlatinib in Advanced Anaplastic Lymphoma Kinase-Positive Non-Small-Cell Lung Cancer.

PURPOSE: Lorlatinib is a potent, brain-penetrant, third-generation anaplastic lymphoma kinase (ALK)/ROS1 tyrosine kinase inhibitor (TKI) with robust clinical activity in advanced ALK-positive non-small-cell lung cancer, including in patients who have failed prior ALK TKIs. Molecular determinants of response to lorlatinib have not been established, but preclinical data suggest that ALK resistance mutations may represent a biomarker of response in previously treated patients. PATIENTS AND METHODS: Baseline plasma and tumor tissue samples were collected from 198 patients with ALK-positive non-small-cell lung cancer from the registrational phase II study of lorlatinib. We analyzed plasma DNA for ALK mutations using Guardant360. Tumor tissue DNA was analyzed using an ALK mutation-focused next-generation sequencing assay. Objective response rate, duration of response, and progression-free survival were evaluated according to ALK mutation status. RESULTS: Approximately one quarter of patients had ALK mutations detected by plasma or tissue genotyping. In patients with crizotinib-resistant disease, the efficacy of lorlatinib was comparable among patients with and without ALK mutations using plasma or tissue genotyping. In contrast, in patients who had failed 1 or more second-generation ALK TKIs, objective response rate was higher among patients with ALK mutations (62% v 32% [plasma]; 69% v 27% [tissue]). Progression-free survival was similar in patients with and without ALK mutations on the basis of plasma genotyping (median, 7.3 months v 5.5 months; hazard ratio, 0.81) but significantly longer in patients with ALK mutations identified by tissue genotyping (median, 11.0 months v 5.4 months; hazard ratio, 0.47). CONCLUSION: In patients who have failed 1 or more second-generation ALK TKIs, lorlatinib shows greater efficacy in patients with ALK mutations compared with patients without ALK mutations. Tumor genotyping for ALK mutations after failure of a second-generation TKI may identify patients who are more likely to derive clinical benefit from lorlatinib.

Lorlatinib in patients with ALK-positive non-small-cell lung cancer: results from a global phase 2 study.

BACKGROUND: Lorlatinib is a potent, brain-penetrant, third-generation inhibitor of ALK and ROS1 tyrosine kinases with broad coverage of ALK mutations. In a phase 1 study, activity was seen in patients with ALK-positive non-small-cell lung cancer, most of whom had CNS metastases and progression after ALK-directed therapy. We aimed to analyse the overall and intracranial antitumour activity of lorlatinib in patients with ALK-positive, advanced non-small-cell lung cancer. METHODS: In this phase 2 study, patients with histologically or cytologically ALK-positive or ROS1-positive, advanced, non-small-cell lung cancer, with or without CNS metastases, with an Eastern Cooperative Oncology Group performance status of 0, 1, or 2, and adequate end-organ function were eligible. Patients were enrolled into six different expansion cohorts (EXP1-6) on the basis of ALK and ROS1 status and previous therapy, and were given lorlatinib 100 mg orally once daily continuously in 21-day cycles. The primary endpoint was overall and intracranial tumour response by independent central review, assessed in pooled subgroups of ALK-positive patients. Analyses of activity and safety were based on the safety analysis set (ie, all patients who received at least one dose of lorlatinib) as assessed by independent central review. Patients with measurable CNS metastases at baseline by independent central review were included in the intracranial activity analyses. In this report, we present lorlatinib activity data for the ALK-positive patients (EXP1-5 only), and safety data for all treated patients (EXP1-6). This study is ongoing and is registered with ClinicalTrials.gov, number NCT01970865. FINDINGS: Between Sept 15, 2015, and Oct 3, 2016, 276 patients were enrolled: 30 who were ALK positive and treatment naive (EXP1); 59 who were ALK positive and received previous crizotinib without (n=27; EXP2) or with (n=32; EXP3A) previous chemotherapy; 28 who were ALK positive and received one previous non-crizotinib ALK tyrosine kinase inhibitor, with or without chemotherapy (EXP3B); 112 who were ALK positive with two (n=66; EXP4) or three (n=46; EXP5) previous ALK tyrosine kinase inhibitors with or without chemotherapy; and 47 who were ROS1 positive with any previous treatment (EXP6). One patient in EXP4 died before receiving lorlatinib and was excluded from the safety analysis set. In treatment-naive patients (EXP1), an objective response was achieved in 27 (90·0%; 95% CI 73·5-97·9) of 30 patients. Three patients in EXP1 had measurable baseline CNS lesions per independent central review, and objective intracranial responses were observed in two (66·7%; 95% CI 9·4-99·2). In ALK-positive patients with at least one previous ALK tyrosine kinase inhibitor (EXP2-5), objective responses were achieved in 93 (47·0%; 39·9-54·2) of 198 patients and objective intracranial response in those with measurable baseline CNS lesions in 51 (63·0%; 51·5-73·4) of 81 patients. Objective response was achieved in 41 (69·5%; 95% CI 56·1-80·8) of 59 patients who had only received previous crizotinib (EXP2-3A), nine (32·1%; 15·9-52·4) of 28 patients with one previous non-crizotinib ALK tyrosine kinase inhibitor (EXP3B), and 43 (38·7%; 29·6-48·5) of 111 patients with two or more previous ALK tyrosine kinase inhibitors (EXP4-5). Objective intracranial response was achieved in 20 (87·0%; 95% CI 66·4-97·2) of 23 patients with measurable baseline CNS lesions in EXP2-3A, five (55·6%; 21·2-86·3) of nine patients in EXP3B, and 26 (53·1%; 38·3-67·5) of 49 patients in EXP4-5. The most common treatment-related adverse events across all patients were hypercholesterolaemia (224 [81%] of 275 patients overall and 43 [16%] grade 3-4) and hypertriglyceridaemia (166 [60%] overall and 43 [16%] grade 3-4). Serious treatment-related adverse events occurred in 19 (7%) of 275 patients and seven patients (3%) permanently discontinued treatment because of treatment-related adverse events. No treatment-related deaths were reported. INTERPRETATION: Consistent with its broad ALK mutational coverage and CNS penetration, lorlatinib showed substantial overall and intracranial activity both in treatment-naive patients with ALK-positive non-small-cell lung cancer, and in those who had progressed on crizotinib, second-generation ALK tyrosine kinase inhibitors, or after up to three previous ALK tyrosine kinase inhibitors. Thus, lorlatinib could represent an effective treatment option for patients with ALK-positive non-small-cell lung cancer in first-line or subsequent therapy. FUNDING: Pfizer.

Comparison of two doses of intravenous temsirolimus in patients with relapsed/refractory mantle cell lymphoma.

Temsirolimus 175 mg once-weekly for 3 weeks, followed by 75 mg once-weekly intravenously dosed (175/75 mg) is approved in the European Union for treatment of relapsed/refractory mantle cell lymphoma (MCL). A phase IV study explored whether similar efficacy, but improved safety could be achieved with 75 mg without 175 mg loading doses (ClinicaTrials.gov: NCT01180049). Patients with relapsed/refractory MCL were randomized to once-weekly temsirolimus 175/75 mg (n = 47) or 75 mg (n = 42). Treatment continued until objective disease progression. Primary endpoint: progression-free survival (PFS). Secondary endpoints included overall survival (OS) and adverse events (AEs). Median PFS was 4.3 versus 4.5 months (hazard ratio [HR] 0.731; 80% confidence interval [CI], 0.520-1.027), and median OS 18.7 versus 11.0 months (HR 0.681; 80% CI, 0.472-0.982) with 175/75 mg versus 75 mg. There were fewer patients with serious AEs, dose reduction, or death with 175/75 mg (57.4%, 48.9%, and 48.9%) versus 75 mg (73.8%, 64.3%, and 65.1%). Temsirolimus 175/75 mg remains the preferred dosing regimen for relapsed/refractory MCL.

Lorlatinib in non-small-cell lung cancer with ALK or ROS1 rearrangement: an international, multicentre, open-label, single-arm first-in-man phase 1 trial.

BACKGROUND: Most patients with anaplastic lymphoma kinase (ALK)-rearranged or ROS proto-oncogene 1 (ROS1)-rearranged non-small-cell lung cancer (NSCLC) are sensitive to tyrosine kinase inhibitor (TKI) therapy, but resistance invariably develops, commonly within the CNS. This study aimed to analyse the safety, efficacy, and pharmacokinetic properties of lorlatinib, a novel, highly potent, selective, and brain-penetrant ALK and ROS1 TKI with preclinical activity against most known resistance mutations, in patients with advanced ALK-positive or ROS1-positive NSCLC. METHODS: In this international multicentre, open-label, single-arm, first-in-man phase 1 dose-escalation study, eligible patients had advanced ALK-positive or ROS1-positive NSCLC and were older than 18 years, with an Eastern Cooperative Oncology Group performance status of 0 or 1, and adequate end-organ function. Lorlatinib was administered orally to patients at doses ranging from 10 mg to 200 mg once daily or 35 mg to 100 mg twice daily, with a minimum of three patients receiving each dose. For some patients, tumour biopsy was done before lorlatinib treatment to identify ALK resistance mutations. Safety was assessed in patients who received at least one dose of lorlatinib; efficacy was assessed in the intention-to-treat population (patients who received at least one dose of study treatment and had either ALK or ROS1 rearrangement). The primary endpoint was dose-limiting toxicities during cycle 1 according to investigator assessment; secondary endpoints included safety, pharmacokinetics, and overall response. This study is ongoing and is registered with ClinicalTrials.gov, number NCT01970865. FINDINGS: Between Jan 22, 2014, and July 10, 2015, 54 patients received at least one dose of lorlatinib, including 41 (77%) with ALK-positive and 12 (23%) with ROS1-positive NSCLC; one patient had unconfirmed ALK and ROS1 status. 28 (52%) patients had received two or more TKIs, and 39 (72%) patients had CNS metastases. The most common treatment-related adverse events among the 54 patients were hypercholesterolaemia (39 [72%] of 54 patients), hypertriglyceridaemia (21 [39%] of 54 patients), peripheral neuropathy (21 [39%] of 54 patients), and peripheral oedema (21 [39%] of 54 patients). One dose-limiting toxicity occurred at 200 mg (the patient did not take at least 16 of 21 prescribed total daily doses in cycle 1 because of toxicities attributable to study drug, which were grade 2 neurocognitive adverse events comprising slowed speech and mentation and word-finding difficulty). No maximum tolerated dose was identified. The recommended phase 2 dose was selected as 100 mg once daily. For ALK-positive patients, the proportion of patients who achieved an objective response was 19 (46%) of 41 patients (95% CI 31-63); for those who had received two or more TKIs, the proportion of patients with an objective response was 11 (42%) of 26 patients (23-63). In ROS1-positive patients, including seven crizotinib-pretreated patients, an objective response was achieved by six (50%) of 12 patients (95% CI 21-79). INTERPRETATION: In this phase 1, dose-escalation study, lorlatinib showed both systemic and intracranial activity in patients with advanced ALK-positive or ROS1-positive NSCLC, most of whom had CNS metastases and had previously had two or more TKI treatments fail. Therefore, lorlatinib might be an effective therapeutic strategy for patients with ALK-positive NSCLC who have become resistant to currently available TKIs, including second-generation ALK TKIs, and is being investigated in a phase 3 randomised controlled trial comparing lorlatinib to crizotinib (ClinicalTrials.gov, NCT03052608). FUNDING: Pfizer.

Randomized phase III trial of temsirolimus and bevacizumab versus interferon alfa and bevacizumab in metastatic renal cell carcinoma: INTORACT trial.

PURPOSE: To prospectively determine the efficacy of combination therapy with temsirolimus plus bevacizumab versus interferon alfa (IFN) plus bevacizumab in metastatic renal cell carcinoma (mRCC). PATIENTS AND METHODS: In a randomized, open-label, multicenter, phase III study, patients with previously untreated predominantly clear-cell mRCC were randomly assigned, stratified by prior nephrectomy and Memorial Sloan-Kettering Cancer Center prognostic group, to receive the combination of either temsirolimus (25 mg intravenously, weekly) or IFN (9 MIU subcutaneously thrice weekly) with bevacizumab (10 mg/kg intravenously, every 2 weeks). The primary end point was independently assessed progression-free survival (PFS). RESULTS: Median PFS in patients treated with temsirolimus/bevacizumab (n = 400) versus IFN/bevacizumab (n = 391) was 9.1 and 9.3 months, respectively (hazard ratio [HR], 1.1; 95% CI, 0.9 to 1.3; P = .8). There were no significant differences in overall survival (25.8 ν 25.5 months; HR, 1.0; P = .6) or objective response rate (27.0% ν 27.4%) with temsirolimus/bevacizumab versus IFN/bevacizumab, respectively. Patients receiving temsirolimus/bevacizumab reported significantly higher overall mean scores in the Functional Assessment of Cancer Therapy-Kidney Symptom Index (FKSI) -15 and FKSI-Disease Related Symptoms subscale compared with IFN/bevacizumab (indicating improvement); however, no differences in global health outcome measures were observed. Treatment-emergent all-causality grade ≥ 3 adverse events more common (P < .001) with temsirolimus/bevacizumab were mucosal inflammation, stomatitis, hypophosphatemia, hyperglycemia, and hypercholesterolemia, whereas neutropenia was more common with IFN/bevacizumab. Incidence of pneumonitis with temsirolimus/bevacizumab was 4.8%, mostly grade 1 or 2. CONCLUSION: Temsirolimus/bevacizumab combination therapy was not superior to IFN/bevacizumab for first-line treatment in clear-cell mRCC.

Phase II trial of temsirolimus in children with high-grade glioma, neuroblastoma and rhabdomyosarcoma.

PURPOSE: A phase II study of temsirolimus was conducted in children and adolescents with high-grade glioma, neuroblastoma or rhabdomyosarcoma. PATIENTS AND METHODS: Temsirolimus 75 mg/m(2) was administered once weekly until disease progression or intolerance. Using the Simon 2-stage design, further enrolment in each disease cohort required ≥ 2 objective responses within the first 12 weeks for the first 12 evaluable patients (those who received ≥ 3 temsirolimus doses). RESULTS: Fifty-two heavily pretreated patients with relapsed (12%) or refractory (88%) disease, median age 8 years (range 1-21 years), were enroled and treated. One patient with neuroblastoma achieved confirmed partial response within the first 12 weeks; thus, none of the 3 cohorts met the criterion for continued enrolment. Disease stabilisation at week 12 was observed in 7 of 17 patients (41%) with high-grade glioma (5 diffuse pontine gliomas, 1 glioblastoma multiforme and 1 anaplastic astrocytoma), 6 of 19 (32%) with neuroblastoma and 1 of 16 (6%) with rhabdomyosarcoma (partial response confirmed at week 18). In the three cohorts, median duration of stable disease or better was 128, 663 and 75 d, respectively. The most common treatment-related adverse events were thrombocytopaenia, hyperlipidaemia and aesthenia. Pharmacokinetic findings were similar to those observed in adults. CONCLUSIONS: Temsirolimus administered weekly at the dose of 75 mg/m(2) did not meet the primary objective efficacy threshold in children with high-grade glioma, neuroblastoma or rhabdomyosarcoma; however, meaningful prolonged stable disease merits further evaluation in combination therapy.

Phase I study of temsirolimus in pediatric patients with recurrent/refractory solid tumors.

PURPOSE: To determine dose-limiting toxicities, maximum-tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of weekly intravenous temsirolimus, a mammalian target of rapamycin (mTOR) signaling pathway inhibitor, in pediatric patients with recurrent or refractory solid tumors. PATIENTS AND METHODS: Cohorts of three to six patients 1 to 21 years of age with recurrent or refractory solid tumors were treated with a 1-hour intravenous infusion of temsirolimus weekly for 3 weeks per course at one of four dose levels: 10, 25, 75, or 150 mg/m(2). During the first two courses, pharmacokinetic and pharmacodynamic evaluations (phosphorylation of S6, AKT, and 4EBP1 in peripheral-blood mononuclear cells) were performed. RESULTS: Dose-limiting toxicity (grade 3 anorexia) occurred in one of 18 evaluable patients at the 150 mg/m(2) level, which was determined to be tolerable, and an MTD was not identified. In 13 patients evaluable for response after two courses of therapy, one had complete response (CR; neuroblastoma) and five had stable disease (SD). Four patients (three SDs + one CR) remained on treatment for more than 4 months. The sum of temsirolimus and sirolimus areas under the concentration-time curve was comparable to values in adults. AKT and 4EBP1 phosphorylation were inhibited at all dose levels, particularly after two courses. CONCLUSION: Weekly intravenous temsirolimus is well tolerated in children with recurrent solid tumors, demonstrates antitumor activity, has pharmacokinetics similar to those in adults, and inhibits the mTOR signaling pathway in peripheral-blood mononuclear cells. Further studies are needed to define the optimal dose for use in combination with other antineoplastic agents in pediatric patients.

Phase III study to evaluate temsirolimus compared with investigator's choice therapy for the treatment of relapsed or refractory mantle cell lymphoma.

PURPOSE: Temsirolimus, a specific inhibitor of the mammalian target of rapamycin kinase, has shown clinical activity in mantle cell lymphoma (MCL). We evaluated two dose regimens of temsirolimus in comparison with investigator's choice single-agent therapy in relapsed or refractory disease. PATIENTS AND METHODS: In this multicenter, open-label, phase III study, 162 patients with relapsed or refractory MCL were randomly assigned (1:1:1) to receive one of two temsirolimus regimens: 175 mg weekly for 3 weeks followed by either 75 mg (175/75-mg) or 25 mg (175/25-mg) weekly, or investigator's choice therapy from prospectively approved options. The primary end point was progression-free survival (PFS) by independent assessment. RESULTS: Median PFS was 4.8, 3.4, and 1.9 months for the temsirolimus 175/75-mg, 175/25-mg, and investigator's choice groups, respectively. Patients treated with temsirolimus 175/75-mg had significantly longer PFS than those treated with investigator's choice therapy (P = .0009; hazard ratio = 0.44); those treated with temsirolimus 175/25-mg showed a trend toward longer PFS (P = .0618; hazard ratio = 0.65). Objective response rate was significantly higher in the 175/75-mg group (22%) compared with the investigator's choice group (2%; P = .0019). Median overall survival for the temsirolimus 175/75-mg group and the investigator's choice group was 12.8 months and 9.7 months, respectively (P = .3519). The most frequent grade 3 or 4 adverse events in the temsirolimus groups were thrombocytopenia, anemia, neutropenia, and asthenia. CONCLUSION: Temsirolimus 175 mg weekly for 3 weeks followed by 75 mg weekly significantly improved PFS and objective response rate compared with investigator's choice therapy in patients with relapsed or refractory MCL.