Larotrectinib efficacy and safety in adult patients with tropomyosin receptor kinase fusion sarcomas.

BACKGROUND: Larotrectinib, a first-in-class, highly selective tropomyosin receptor kinase (TRK) inhibitor, has demonstrated efficacy in adult and pediatric patients with various solid tumors harboring NTRK gene fusions. This subset analysis focuses on the efficacy and safety of larotrectinib in an expanded cohort of adult patients with TRK fusion sarcomas. METHODS: Patients (≥18 years old) with sarcomas harboring NTRK gene fusions were identified from three clinical trials. Patients received larotrectinib 100 mg orally twice daily. Response was investigator-assessed per RECIST v1.1. Data cutoff was July 20, 2021. RESULTS: At the data cutoff, 36 adult patients with TRK fusion sarcomas had initiated larotrectinib therapy: two (6%) patients had bone sarcomas, four (11%) had gastrointestinal stromal tumors, and 30 (83%) had soft tissue sarcomas. All patients were evaluable for response and demonstrated an objective response rate of 58% (95% confidence interval, 41-74). Patients responded well to larotrectinib regardless of number of prior lines of therapy. Adverse events (AEs) were mostly grade 1/2. Grade 3 treatment-emergent AEs (TEAEs) occurred in 15 (42%) patients. There were no grade 4 TEAEs. Two grade 5 TEAEs were reported, neither of which were considered related to larotrectinib. Four (11%) patients permanently discontinued treatment due to TEAEs. CONCLUSIONS: Larotrectinib demonstrated robust and durable responses, extended survival benefit, and a favorable safety profile in adult patients with TRK fusion sarcomas with longer follow-up. These results continue to demonstrate that testing for NTRK gene fusions should be incorporated into the clinical management of adult patients with various types of sarcomas. PLAIN LANGUAGE SUMMARY: Tropomyosin receptor kinase (TRK) fusion proteins result from translocations involving the NTRK gene and cause cancer in a range of tumor types. Larotrectinib is an agent that specifically targets TRK fusion proteins and is approved for the treatment of patients with TRK fusion cancer. This study looked at how well larotrectinib worked in adult patients with sarcomas caused by TRK fusion proteins. Over half of patients had a durable response to larotrectinib, with no unexpected side effects. These results show that larotrectinib is safe and effective in adult patients with TRK fusion sarcomas.

Prevalence and clinico-genomic characteristics of patients with TRK fusion cancer in China.

Neurotrophic tyrosine kinase (NTRK) fusions involving NTRK1, NTRK2, and NTRK3 were found in a broad range of solid tumors as driver gene variants. However, the prevalence of NTRK fusions in Chinese solid tumor patients is rarely reported. Based on the next-generation sequencing data from 10,194 Chinese solid tumor patients, we identified approximately 0.4% (40/10,194) of Chinese solid tumor patients with NTRK fusion. NTRK fusions were most frequently detected in soft tissue sarcoma (3.0%), especially in the fibrosarcoma subtype (12.7%). A total of 29 NTRK fusion patterns were identified, of which 11 were rarely reported. NTRK fusion mostly co-occurred with TP53 (38%), CDKN2A (23%), and ACVR2A (18%) and rarely with NTRK amplification (5.0%) and single nucleotide variants (2.5%). DNA-based NTRK fusion sequencing exhibited a higher detection rate than pan-TRK immunohistochemistry (100% vs. 87.5%). Two patients with NTRK fusions showed clinical responses to larotrectinib, supporting the effective response of NTRK fusion patients to TRK inhibitors.

Survival Outcomes of Patients With Tropomyosin Receptor Kinase Fusion-Positive Cancer Receiving Larotrectinib Versus Standard of Care: A Matching-Adjusted Indirect Comparison Using Real-World Data.

PURPOSE: Larotrectinib, a highly specific tropomyosin receptor kinase (TRK) inhibitor, previously demonstrated high response rates in single-arm trials of patients with TRK fusion-positive cancer, but there are limited data on comparative effectiveness against standard-of-care (SoC) regimens used in routine health care practice, before widespread adoption of TRK inhibitors as SoC for TRK fusion-positive cancers. Matching-adjusted indirect comparison, a validated methodology that balances population characteristics to facilitate cross-trial comparisons, was used to compare the overall survival (OS) of larotrectinib versus non-TRK-inhibitor SoC. MATERIALS AND METHODS: Individual patient data from three larotrectinib trials (ClinicalTrials.gov identifiers: NCT02122913, NCT02637687, and NCT02576431) were compared with published aggregate real-world data from patients with locally advanced/metastatic TRK fusion-positive cancer identified in the Flatiron Health/Foundation Medicine database. OS was defined as the time from advanced/metastatic disease diagnosis to death. After matching population characteristics, the analyses included (1) a log-rank test of equality to test whether the two groups were similar before larotrectinib initiation; and (2) estimation of treatment effect of larotrectinib versus non-TRK-inhibitor SoC. These analyses are limited to prognostic variables available in real-world data. RESULTS: Eighty-five larotrectinib patients and 28 non-TRK-inhibitor SoC patients were included in the analyses. After matching, log-rank testing showed no difference in baseline characteristics between the two groups (P = .31). After matching, larotrectinib was associated with a 78% lower risk of death, compared with non-TRK-inhibitor SoC (adjusted hazard ratio, 0.22 [95% CI, 0.09 to 0.52]; P = .001); median OS was 39.7 months (95% CI: 16.4, NE [not estimable]) for larotrectinib and 10.2 months (95% CI: 7.2, 14.1) for SoC. CONCLUSION: Matching-adjusted indirect comparison analyses suggest longer OS with larotrectinib, compared with non-TRK-inhibitor SoC, in adult patients with TRK fusion-positive cancer.

A rapid and durable response to larotrectinib in a patient with NTRK fusion-positive secretory carcinoma originating from the external auditory canal.

For decades, no clear consensus existed on the standard treatment option for malignant tumors of the external auditory canal, an extremely rare disease. Here we report the case of a 55-year-old female patient with secretory carcinoma that originated from the left external auditory canal. Magnetic resonance imaging (MRI) at baseline showed that the tumor had extended to the medulla oblongata despite surgical and radiation treatments for more than 20 years from the initial diagnosis. Based on the results of a next-generation sequencing test of a formalin-fixed paraffin-embedded surgical specimen indicating that the tumor harbored ETV6-NTRK3 fusion, the patient was enrolled in a global basket study of larotrectinib, an oral selective tropomyosin receptor kinase (TRK) inhibitor. Three weeks after the start of larotrectinib treatment, MRI showed only small remnants of the tumor in the medulla oblongata and the patient's headache before the treatment had disappeared. Subsequent MRI after 12 weeks of treatment confirmed the complete disappearance of the tumor. The patient repeated grade 2 flu-like symptoms related to treatment, but did not experience any other grade 2 or worse treatment-related adverse events. TRK inhibitors, such as larotrectinib, exert potent antitumor activity against neurotrophic tyrosine receptor kinase (NTRK) fusion-positive tumors in a tumor-agnostic manner. To the best of our knowledge, this is the first report on NTRK fusion-positive secretory carcinoma of the external auditory canal, and this report provides a valuable insight into the management of the extremely rare but now treatable malignancy.

Larotrectinib Treatment for Patients With TRK Fusion-Positive Salivary Gland Cancers.

BACKGROUND: Larotrectinib is a first-in-class, highly selective, and central nervous system-active tropomyosin receptor kinase (TRK) inhibitor approved for the treatment of adult and pediatric patients with TRK fusion cancer. We report the efficacy and safety of larotrectinib in patients with TRK fusion-positive salivary gland cancers. PATIENTS AND METHODS: Patients with TRK fusion-positive salivary gland cancer treated with larotrectinib were identified from two clinical trials (NCT02122913 and NCT02576431). Patients received larotrectinib 100 mg twice daily (BID) except for one patient who received 150 mg BID in the phase I trial. The primary endpoint was objective response rate (ORR) as assessed by the investigator using Response Evaluation Criteria in Solid Tumors version 1.1. RESULTS: At the data cut-off (July 20, 2020), 24 patients with TRK fusion-positive salivary gland cancer had been treated. The most common histologies were secretory carcinoma (54%), adenocarcinoma (25%), and mucoepidermoid carcinoma (13%). All 24 patients had an ETV6-NTRK3 gene fusion. The ORR was 92% (95% confidence interval, 73-99). Best overall response was complete response in three (13%) patients, partial response in 19 (79%), and progressive disease in two (8%). The rate of progression-free survival at 24 months was 78% (median follow-up 30.9 months). Most treatment-related adverse events (AEs) were grade 1-2, and no patients discontinued treatment due to AEs. CONCLUSION: Larotrectinib demonstrated robust and durable efficacy in patients with TRK fusion-positive salivary gland tumors of various histologies, and a favorable safety profile. These findings support NTRK gene fusion testing in patients with advanced salivary gland cancers. CLINICALTRIALS.GOV NUMBERS: NCT02122913 and NCT02576431.

Efficacy and safety of larotrectinib in patients with TRK fusion-positive thyroid carcinoma.

Objective: Larotrectinib is a highly selective tropomyosin receptor kinase (TRK) inhibitor with demonstrated efficacy across various TRK fusion-positive solid tumours. We assessed the efficacy and safety of larotrectinib in patients with TRK fusion-positive thyroid carcinoma (TC). Methods: We pooled data from three phase I/II larotrectinib clinical trials (NCT02576431, NCT02122913, and NCT02637687). The primary endpoint was the investigator-assessed objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors v1.1. Secondary endpoints included duration of response (DoR), progression-free survival (PFS), overall survival (OS), and safety. Data cut-off: July 2020. Results: Twenty-nine patients (median age: 60; range: 6-80) with TRK fusion-positive TC were treated. Tumour histology was papillary (PTC) in 20 (69%) patients, follicular (FTC) in 2 (7%), and anaplastic (ATC) in 7 (24%) patients. Among 28 evaluable patients, ORR was 71% (95% CI: 51-87); best responses were complete response in 2 (7%) patients, partial response in 18 (64%), stable disease in 4 (14%), progressive disease in 3 (11%), and undetermined in 1 (4%) due to clinical progression prior to the first post-baseline assessment. ORR was 86% (95% CI: 64-97) for PTC/FTC and 29% (95% CI 4-71) for ATC. Median time to response was 1.87 months (range 1.64-3.68). The 24-month DoR, PFS, and OS rates were 81, 69, and 76%, respectively. Treatment-related adverse events were mainly grades 1-2. Conclusion: In TRK fusion-positive TC, larotrectinib demonstrates rapid and durable disease control and a favourable safety profile in patients with advanced disease requiring systemic therapy. Significance statement: NTRK gene fusions are known oncogenic drivers and have been identified in various histologies of thyroid carcinoma, most commonly in papillary thyroid carcinoma. This is the first publication specifically studying a TRK inhibitor in a cohort of TRK fusion-positive thyroid carcinoma patients. In the current study, the highly selective TRK inhibitor larotrectinib showed durable antitumour efficacy and a favourable safety profile in patients with TRK fusion-positive thyroid carcinoma. Our findings show that patients with advanced non-medullary thyroid carcinoma who may require systemic therapy could be considered for testing for gene fusions by next-generation sequencing.

Efficacy and Safety of Larotrectinib in Patients With Tropomyosin Receptor Kinase Fusion-Positive Lung Cancers.

PURPOSE: Larotrectinib is a highly selective and CNS-active tropomyosin receptor kinase (TRK) inhibitor that has demonstrated efficacy across TRK fusion-positive cancers, regardless of the tumor type. The aim of this study was to assess the efficacy and safety of larotrectinib in patients with TRK fusion-positive lung cancers. MATERIALS AND METHODS: Data from two global, multicenter, registrational clinical trials of patients treated with larotrectinib were analyzed: a phase II adult and young adult basket trial (NCT02576431) and a phase I adult trial (NCT02122913). The primary end point was objective response rate (ORR). RESULTS: By July 20, 2020, 20 patients with TRK fusion-positive lung cancer had been treated. The ORR by investigator assessment among 15 evaluable patients was 73% (95% CI, 45 to 92); one (7%) patient had a complete response, 10 (67%) had a partial response, three (20%) had stable disease, and one (7%) had progressive disease as best response. The median duration of response, progression-free survival, and overall survival were 33.9 months (95% CI, 5.6 to 33.9), 35.4 months (95% CI, 5.3 to 35.4), and 40.7 months (95% CI, 17.2 to not estimable), respectively. Among patients with baseline CNS metastases, the ORR was 63% (95% CI, 25 to 91). Adverse events were mainly grade 1 or 2. CONCLUSION: Larotrectinib is highly active with rapid and durable responses, extended survival benefit, and a favorable long-term safety profile in patients with advanced lung cancer harboring NTRK gene fusions, including those with CNS metastases. These findings support routine testing for NTRK fusions in patients with lung cancer.

Evaluation of Proton Pump Inhibitor Esomeprazole on Crizotinib Pharmacokinetics in Healthy Participants.

Crizotinib is a small-molecule, multitargeted tyrosine kinase inhibitor that exhibits decreased aqueous solubility at a higher pH. This open-label, randomized, phase 1 study (NCT01549574) evaluated the effect of multiple doses of the proton pump inhibitor esomeprazole on the pharmacokinetics (PK) of crizotinib and the safety of crizotinib with or without esomeprazole in healthy adults. Participants received a single 250-mg crizotinib dose after overnight fast or a single 250-mg crizotinib dose following esomeprazole 40 mg/day for 5 days. After a washout of ≥14 days, participants crossed over to the alternate treatment. Blood samples for plasma analysis were taken up to 144 hours after crizotinib dosing and relevant PK parameters estimated. Safety was assessed in all participants receiving ≥1 dose of study medication. Fifteen participants were evaluable for PK and safety for each treatment. Coadministration with esomeprazole resulted in a slight decrease (≈10%) in the crizotinib geometric mean area under the plasma concentration-time profile from time 0 to infinity (adjusted geometric mean ratio, 89.81% [90% confidence interval, 79.05-102.03]). Coadministration of esomeprazole did not affect peak crizotinib exposure. Adverse events (AEs) occurred in similar numbers between treatments; no serious or severe AEs occurred. The most common AE was diarrhea. Although esomeprazole decreased total exposure of crizotinib, it is not considered clinically meaningful, and dose modification is not required when crizotinib is coadministered with agents that affect gastric pH.

Effects of Renal Function on Crizotinib Pharmacokinetics: Dose Recommendations for Patients with ALK-Positive Non-Small Cell Lung Cancer.

BACKGROUND AND OBJECTIVES: Crizotinib (250 mg twice daily) is the first anaplastic lymphoma kinase (ALK) inhibitor approved for treatment of ALK-positive non-small-cell lung cancer (NSCLC). The objectives of the current study were to evaluate the effects of mild, moderate, and severe renal impairment on crizotinib pharmacokinetics and to make crizotinib dosing recommendations for ALK-positive NSCLC patients with renal impairment on the basis of the findings. METHODS: The effects of varying degrees of renal impairment on crizotinib pharmacokinetics were evaluated by: (1) analysis of mild and moderate renal impairment on multiple-dose pharmacokinetics of crizotinib in ALK-positive NSCLC patients from the PROFILE 1001 and PROFILE 1005 trials; (2) analysis of severe renal impairment on single-dose pharmacokinetics of crizotinib in volunteers (Study 1020); and (3) prediction of the effect of severe renal impairment on multiple-dose crizotinib pharmacokinetics using a physiologically-based pharmacokinetic model of crizotinib. RESULTS: No clinically relevant changes in plasma crizotinib exposure were observed in NSCLC patients with mild or moderate renal impairment. After a single 250-mg dose, the area under the plasma concentration-time curve (AUC) for crizotinib was 1.8-fold greater in subjects with severe renal impairment than in those with normal renal function. Physiologically-based pharmacokinetic modeling indicated a similar increase in steady-state AUC after multiple dosing. CONCLUSIONS: These results suggest no dose adjustment for patients with mild or moderate renal impairment. The recommended crizotinib dose for patients with severe renal impairment not requiring dialysis is 250 mg once daily.

Phase I Results from a Study of Crizotinib in Combination with Erlotinib in Patients with Advanced Nonsquamous Non-Small Cell Lung Cancer.

INTRODUCTION: This phase I trial was conducted to determine the safety, maximum tolerated dose (MTD)/recommended phase II dose, and efficacy of crizotinib plus erlotinib in patients with advanced NSCLC. METHODS: Patients with NSCLC and an Eastern Cooperative Oncology Group performance status of 0 to 2 after failure of one or two prior chemotherapy regimens were eligible. Erlotinib, 100 mg, was given continuously once daily starting between day -14 and -7; crizotinib, 200 mg twice daily (dose level 1) or 150 mg twice daily (dose level -1), was added continuously beginning on day 1 of treatment cycle 1. Potential pharmacokinetic interactions between crizotinib and erlotinib were evaluated. RESULTS: Twenty-seven patients received treatment; 26 received crizotinib plus erlotinib. Frequent adverse events were diarrhea, rash, decreased appetite, and fatigue. Dose-limiting toxicities were dehydration, diarrhea, dry eye, dysphagia, dyspepsia, esophagitis and vomiting. The MTD was crizotinib, 150 mg twice daily, with erlotinib, 100 mg once daily. Crizotinib increased the erlotinib area under the concentration-time curve 1.5-fold (dose level -1) and 1.8-fold (dose level 1). The plasma level of crizotinib appeared to be unaffected by coadministration of erlotinib. Two patients whose tumors harbored activating EGFR mutations achieved confirmed partial responses, one at each crizotinib dose level. CONCLUSIONS: The MTD of the combination of crizotinib and erlotinib in patients with advanced NSCLC was crizotinib, 150 mg twice daily, with erlotinib, 100 mg once daily, which is less than the approved dose of either agent. The phase II portion of the study was not initiated.

The effects of ketoconazole and rifampin on the single-dose pharmacokinetics of crizotinib in healthy subjects.

PURPOSE: To investigate the potential effects of strong CYP3A inhibitor ketoconazole and strong CYP3A inducer rifampin on the pharmacokinetics of crizotinib in human. METHODS: Two separate open-label, 2-period, 2-treatment, 1-sequence, crossover, single-dose studies were conducted in healthy subjects with and without ketoconazole or rifampin. Series of plasma samples were collected after each crizotinib dose to determine concentration of crizotinib and its metabolite PF-06260182. Relevant pharmacokinetic (PK) parameters for crizotinib and PF096269182 were estimated by standard non-compartmental analysis (NCA) method. RESULTS: Co-administration of a single 150-mg oral dose of crizotinib with the strong CYP3A inhibitor ketoconazole resulted in an area under the plasma-concentration curve extrapolated to infinity (AUC0-inf) 3.2-fold that for crizotinib alone. Co-administration of a single 250-mg crizotinib dose with the strong CYP3A inducer rifampin caused an 82 % decrease in crizotinib AUC0-inf. Respective increases and decreases in systemic exposure to the crizotinib metabolite PF-06260182 following co-administration of ketoconazole and rifampin were greater than those seen for crizotinib. CONCLUSIONS: These findings suggest that CYP3A plays an important role in the metabolism of both crizotinib and PF-06260182, with the extent of this role being greater for PF-06260182. There were no serious adverse events or deaths and no dose reductions or temporary or permanent discontinuations due to drug-related adverse events in either study.

Evaluation of crizotinib absolute bioavailability, the bioequivalence of three oral formulations, and the effect of food on crizotinib pharmacokinetics in healthy subjects.

Crizotinib (Xalkori®) is an orally administered, selective, small-molecule, ATP-competitive inhibitor of the anaplastic lymphoma kinase (ALK) and mesenchymal epithelial transition factor/hepatocyte growth factor receptor tyrosine kinases, and has recently been approved for the treatment of ALK-positive non-small cell lung cancer. The absolute bioavailability of crizotinib, effect of a high-fat meal on crizotinib pharmacokinetics (PK), and bioequivalence of several oral formulations (powder in capsule [PIC], immediate-release tablet [IRT], and commercial formulated capsule [FC]) were evaluated in two phase I clinical studies involving healthy volunteers who received single doses of crizotinib. PK parameters for crizotinib and its metabolite, PF-06260182, were determined using non-compartmental methods. The absolute oral bioavailability of crizotinib was approximately 43%, with a slight decrease in crizotinib exposures (area under the plasma concentration-time profile and maximum plasma concentration) following a high-fat meal that was not considered clinically meaningful. The FC was bioequivalent to the clinical development IRT and PIC formulations. No serious adverse events were observed during either study and the majority of adverse events were mild, the most common being diarrhea. Single-dose crizotinib could be safely administered to healthy subjects.

Phase I trial of the HSP90 inhibitor PF-04929113 (SNX5422) in adult patients with recurrent, refractory hematologic malignancies.

BACKGROUND: Heat shock protein (HSP)90 regulates the function of proteins responsible for cell growth and survival, is overexpressed in many cancers and is an attractive therapeutic target. We undertook a phase 1 trial of PF-04929113 (SNX-5422), a novel oral HSP90 inhibitor, to estimate the maximum tolerated dose and describe the pharmacokinetic and toxicity profiles. PATIENTS AND METHODS: Patients with relapsed, refractory, hematologic malignancies and adequate organ function were eligible. PF-04929113 was administered orally every other day for 21 days of a 28-day cycle. Twenty-five patients were treated, with dose escalation ranging from 5.32 mg/m(2) to 74 mg/m(2) using a 3 plus 3 trial design. RESULTS: All 25 patients enrolled were evaluable for toxicity. Most common toxicities included prolonged QTc interval, diarrhea, pruritus, thrombocytopenia, fatigue, and nausea. Grade 3/4 treatment-related adverse events were experienced by 7/25 patients (28%); thrombocytopenia was the most common (n = 3 grade 3; n = 2 grade 4). Partial response was experienced by a patient with transformed lymphoma, and prolonged stabilization of disease was observed in a patient with multiple myeloma. CONCLUSION: Alternate-day oral dosing of PF-04929113 at 74 mg/m(2) for 21/28 days was generally well tolerated with reversible toxicity. The responses observed in myeloma and lymphoma patients are encouraging.

Pharmacodynamic analysis of tumour perfusion assessed by 15O-water-PET imaging during treatment with sunitinib malate in patients with advanced malignancies.

BACKGROUND: We evaluated pharmacodynamic changes in tumour perfusion using positron emission tomography (PET) imaging with 15O-water to assess biological response to sunitinib, a multitargeted tyrosine kinase inhibitor. METHODS: Patients with advanced malignancies received sunitinib 50 mg/day orally, once daily for 4 weeks on treatment, followed by 2 weeks off treatment, in repeated 6-week cycles. Quantitative measurement of tumour perfusion was assessed using 15O-water-PET at baseline and after 2 weeks of treatment. At least one reference tumour lesion was included in the fields of view and assessed at both time points. Patients also underwent 18 F-fluorodeoxyglucose (FDG)-PET imaging at baseline and after 2 and 4 weeks of treatment. Radiological response of the reference tumour lesion and overall radiological response were assessed at week 12. Serum pharmacokinetic and biomarker analyses were also performed. RESULTS: Data were available for seven patients. Compared with baseline, all patients experienced a decrease in reference tumour blood flow ranging from 20 % to 85 % and also a reduction in the FDG standard uptake value ranging from 29 % to 67 %. Six patients experienced a partial metabolic response based on FDG-PET criteria. Four patients had stable disease defined by radiological response (Response Evaluation Criteria in Solid Tumors) lasting between 4 and 12 cycles. An association between perfusion change and clinical benefit, and biomarker levels including vascular endothelial growth factor was observed. CONCLUSION: Administering sunitinib to patients with advanced malignancies is associated with early biological responses, including decreased blood flow in secondary tumour deposits.

A phase I study of PF-04929113 (SNX-5422), an orally bioavailable heat shock protein 90 inhibitor, in patients with refractory solid tumor malignancies and lymphomas.

PURPOSE: To determine the maximum tolerated dose (MTD), toxicities, and pharmacokinetic/pharmacodynamic profile of the Hsp90 inhibitor PF-04929113 (SNX-5422) in patients with advanced solid tumors and lymphomas. METHODS: This was a single-institution, phase I, dose-escalation study of PF-04929113 administered twice weekly. Endpoints included determination of dose-limiting toxicities (DLT), MTD, the safety profile of PF-04929113, pharmacodynamic assessment of PF-04929113 on Hsp70 induction, pharmacokinetic analysis of PF-04928473 (SNX-2112) and its prodrug PF-04929113, and assessment of response. RESULTS: Thirty-three patients with advanced malignancies were treated. Dose escalation was continued up to 177 mg/m(2) administered orally twice a week. One DLT (nonseptic arthritis) was noted. No grade 4 drug-related adverse events were seen; grade 3 adverse events included diarrhea (9%), nonseptic arthritis (3%), aspartate aminotransferase elevation (3%), and thrombocytopenia (3%). No objective responses were seen in 32 evaluable patients. Fifteen patients (47%) had stable disease; 17 patients (53%) had progressive disease. Pharmacokinetic data revealed rapid absorption, hepatic, and extrahepatic clearance, extensive tissue binding, and almost linear pharmacokinetics of the active drug PF-04928473. Pharmacodynamic studies confirmed inhibition of Hsp90 and a linear correlation between pharmacokinetic parameters and Hsp70 induction. CONCLUSIONS: PF-04929113 administered orally twice a week is well tolerated and inhibits its intended target Hsp90. No objective responses were seen, but long-lasting stabilizations were obtained. Although no clinically significant drug-related ocular toxicity was seen in this study, the development of PF-04929113 has been discontinued because of ocular toxicity seen in animal models and in a separate phase I study.

Safety, pharmacokinetic, and antitumor activity of SU11248, a novel oral multitarget tyrosine kinase inhibitor, in patients with cancer.

PURPOSE: To establish the safety, pharmacokinetics, and recommended dose of sunitinib, a novel oral multitargeting tyrosine kinase inhibitor with antiangiogenic and antitumor properties, in patients with advanced malignancies. PATIENTS AND METHODS: Sunitinib was given orally for 4 weeks every 6 weeks. RESULTS: Twenty-eight patients received doses ranging from 15 to 59 mg/m2 (ranging from 50 mg every other day to 150 mg/d). Dose-limiting toxicities reported at the maximum-tolerated doses > or = 75 mg/d were reversible grade 3 fatigue, grade 3 hypertension, and grade 2 bullous skin toxicity. Therefore, the recommended dose was 50 mg/d. At this dose, the main adverse effects were sore mouth, edema, and thrombocytopenia. Hair discoloration and yellow coloration of the skin were observed at doses > or = 50 mg/d. Pharmacokinetic data indicate that potentially active target plasma concentrations > or = 50 ng/mL can be achieved with moderate interpatient variability and a long half-life compatible with a single daily dosing. Six objective responses were observed in three renal cell carcinomas, one neuroendocrine tumor, one stromal tumor, and one unknown primary adenocarcinoma patient. At higher doses (> or = 75 mg/d), tumor responses were often associated with reduced intratumoral vascularization and central tumor necrosis, eventually resulting in organ perforation or fistula. CONCLUSION: At the dose of 50 mg/d (4 weeks on, 2 weeks off), sunitinib displays manageable toxicity. Antitumor activity supports further studies in patients with renal cell carcinoma, gastrointestinal, neuroendocrine, and stromal tumors. Future studies may consider including prospective imaging techniques such as high frequency ultrasound to monitor tumor density.

A phase 1 study of SU11248 in the treatment of patients with refractory or resistant acute myeloid leukemia (AML) or not amenable to conventional therapy for the disease.

Fifteen patients with refractory AML were treated in a phase 1 study with SU11248, an oral kinase inhibitor of fms-like tyrosine kinase 3 (Flt3), Kit, vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) receptors. Separate cohorts of patients received SU11248 for 4-week cycles followed by either a 2- or a 1-week rest period. At the starting dose level of 50 mg (n = 13), no dose-limiting toxicities were observed. The most frequent grade 2 toxicities were edema, fatigue, and oral ulcerations. Two fatal bleedings possibly related to the disease, one from a concomitant lung cancer and one cerebral bleeding, were observed. At the 75 mg dose level (n = 2), one case each of grade 4 fatigue, hypertension, and cardiac failure was observed, and this dose level was abandoned. All patients with FLT3 mutations (n = 4) had morphologic or partial responses compared with 2 of 10 evaluable patients with wild-type FLT3. Responses, although longer in patients with mutated FLT3, were of short duration. Reductions of cellularity and numbers of Ki-67(+), phospho-Kit(+), phospho-kinase domain-containing receptor-positive (phospho-KDR(+)), phospho-signal transducer and activator of transcription 5-positive (phospho-STAT5(+)), and phospho-Akt(+) cells were detected in bone marrow histology analysis. In summary, monotherapy with SU11248 induced partial remissions of short duration in acute myeloid leukemia (AML) patients. Further evaluation of this compound, for example in combination with chemotherapy, is warranted.

A phase 2 clinical study of SU5416 in patients with refractory acute myeloid leukemia.

Neoangiogenesis has been shown to play an important role in the pathogenesis of acute myeloid leukemia (AML). Autocrine and paracrine secretion of angiogenic and hematopoietic growth factors such as vascular endothelial growth factor (VEGF) and stem cell factor (SCF) in the bone marrow microenvironment may promote proliferation and survival of leukemic blasts. This concept represented the rationale for the initiation of a multicenter phase 2 trial of SU5416, a small molecule inhibitor of phosphorylation of VEGF receptors 1 and 2, c-kit, the SCF receptor, and fms-like tyrosine kinase-3 (FLT3) in patients with advanced AML. Entered into the study were 43 patients with refractory AML or elderly patients not judged medically fit for intensive induction chemotherapy; 42 patients received at least one dose of study drug. Treatment was generally well tolerated, with nausea, headache, and bone pain the most frequent treatment-related side effects. One patient had a morphologic remission (French-American-British [FAB] criteria of complete response without normalization of blood neutrophil and platelet counts) lasting for 2 months. There were 7 patients who achieved a partial response (reduction of blasts by at least 50% in bone marrow and peripheral blood) lasting 1 to 5 months. Patients with AML blasts expressing high levels of VEGF mRNA by quantitative polymerase chain reaction (PCR) had a significantly higher response rate and reduction of bone marrow microvessel density than patients with low VEGF expression consistent with the antiangiogenic effects of SU5416.