Phase I dose-escalation studies of roniciclib, a pan-cyclin-dependent kinase inhibitor, in advanced malignancies

Background:

To evaluate safety, pharmacokinetics, and maximum tolerated dose of roniciclib in patients with advanced malignancies, with dose expansion to evaluate clinical benefit at the recommended phase II dose (RP2D).

Methods:

Two phase I dose-escalation studies evaluated two roniciclib dosing schedules: 3 days on/4 days off or 4 weeks on/2 weeks off. The expansion phase included patients with small-cell lung cancer (SCLC), ovarian cancer, or tumour mutations involving the CDK signalling pathway.

Results:

Ten patients were evaluable in the 4 weeks on/2 weeks off schedule (terminated following limited tolerability) and 47 in the 3 days on/4 days off schedule dose-escalation cohorts. On the 3 days on/4 days off schedule, RP2D was 5 mg twice daily in solid tumours (n=40); undetermined in lymphoid malignancies (n=7). Common roniciclib-related adverse events included nausea (76.6%), fatigue (65.8%), diarrhoea (63.1%), and vomiting (57.7%). Roniciclib demonstrated rapid absorption and dose-proportional increase in exposure. One partial response (1.0%) was observed. In RP2D expansion cohorts, the disease control rate (DCR) was 40.9% for patients with ovarian cancer (n=25), 17.4% for patients with SCLC (n=33), and 33.3% for patients with CDK-related tumour mutations (n=6).

Conclusions:

Roniciclib demonstrated an acceptable safety profile and moderate DCR in 3 days on/4 days off schedule.

Safety and activity of IT-139, a ruthenium-based compound, in patients with advanced solid tumours: a first-in-human, open-label, dose-escalation phase I study with expansion cohort

OBJECTIVE

This phase I clinical study (NCT01415297) evaluated the safety, tolerability, maximum-tolerated dose (MTD), pharmacokinetics and pharmacodynamics of IT-139 (formerly NKP-1339) monotherapy in patients with advanced solid tumours. IT-139, sodium trans-(tetrachlorobis(1H-indazole)ruthenate(III)), is a novel small molecule that suppresses the stress induction of GRP78 in tumour cells. GRP78 is a key regulator of misfolded protein processing, and its upregulation in tumours is associated with intrinsic and drug-induced resistance.

METHODS

Forty-six patients with advanced solid tumours refractory to treatment received intravenous infusions of IT-139 on days 1, 8 and 15 for every 28 days, and doses were evaluated across nine cohorts at 20, 40, 80, 160, 320, 420, 500, 625 and 780 mg/m².

RESULTS

Overall, IT-139 was well tolerated. The treatment-emergent adverse events (AEs) occurring in ≥20% of patients were nausea, fatigue, vomiting, anaemia and dehydration. The majority of patients had AEs that were ≤grade 2, regardless of relationship with the study drug. Of the total 38 efficacy-evaluable patients, one patient with a carcinoid tumour achieved a durable partial response. Nine additional patients achieved stable disease . The MTD was determined to be 625 mg/m². IT-139 exhibited first-order linear pharmacokinetics.

CONCLUSIONS

IT-139 demonstrated a manageable safety profile at the MTD and modest anti-tumour activity in this study of patients with solid tumours refractory to treatment. The lack of dose-limiting haematological toxicity and the absence of neurotoxicity position IT-139 well for use in combination with a broad spectrum of anticancer drugs.

TRIAL REGISTRATION NUMBER

NCT01415297.

Phase 1b trial of proteasome inhibitor carfilzomib with irinotecan in lung cancer and other irinotecan-sensitive malignancies that have progressed on prior therapy (Onyx IST reference number: CAR-IST-553)

Introduction Proteasome inhibition is an established therapy for many malignancies. Carfilzomib, a novel proteasome inhibitor, was combined with irinotecan to provide a synergistic approach in relapsed, irinotecan-sensitive cancers. Materials and Methods Patients with relapsed irinotecan-sensitive cancers received carfilzomib (Day 1, 2, 8, 9, 15, and 16) at three dose levels (20/27 mg/m2, 20/36 mg/m2 and 20/45 mg/m2/day) in combination with irinotecan (Days 1, 8 and 15) at 125 mg/m2/day. Key eligibility criteria included measurable disease, a Zubrod PS of 0 or 1, and acceptable organ function. Patients with stable asymptomatic brain metastases were eligible. Dose escalation utilized a standard 3 + 3 design. Results Overall, 16 patients were enrolled to three dose levels, with four patients replaced. Three patients experienced dose limiting toxicity (DLT) and the maximum tolerated dose (MTD) was exceeded in Cohort 3. The RP2 dose was carfilzomib 20/36 mg/m² (given on Days 1, 2, 8, 9, 15, and 16) and irinotecan 125 mg/m2 (Days 1, 8 and 15). Common Grade (Gr) 3 and 4 toxicities included fatigue (19%), thrombocytopenia (19%), and diarrhea (13%). Conclusions Irinotecan and carfilzomib were well tolerated, with common toxicities of fatigue, thrombocytopenia and neutropenic fever. Objective clinical response was 19% (one confirmed partial response (PR) in small cell lung cancer (SCLC) and two unconfirmed); stable disease (SD) was 6% for a disease control rate (DCR) of 25%. The recommended phase II dose was carfilzomib 20/36 mg/m² and irinotecan125 mg/m2. The phase II evaluation is ongoing in relapsed small cell lung cancer.

Initial gemcitabine/nab-paclitaxel (GA) followed by sequential (S) mFOLFIRINOX or alternating (A) mFOLFIRI in metastatic pancreatic cancer (mPC): The SEENA-1 study

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Background: GA, FOLFIRINOX and FOLFIRI are standard chemotherapy (CTX) regimens for mPC.The optimal introduction of these regimens following GA is not known. This phase II study evaluated 2 different approaches to this question. Methods: Eligibility criteria included 1) untreated mPC, 2) ECOG PS 0/1, 3) organ function adequate for Rx. Patients (pts) were treated according to one of 2 methods following GA given per standard dose/schedule: FOLFIRINOX (bolus 5-FU omitted) for up to 12 cycles at 24 weeks or at time of disease progression (S); or GA alternating with FOLFIRI q8 weeks up to 48 weeks total Rx (A). Results: 54 evaluable pts (28S, 26A) were enrolled . Pt characteristics included median age 65, M/F 48/52% , liver involvement 89%. 17/53 pts (31%) did not achieve disease control at 8 weeks (8 toxicity/complications , 6 disease progression, 3 declined further protocol therapy). Of the remaining 37 pts, 24/13 were treated with S/A regimens, respectively. Grade ≥ 3 treatment toxicities reported while on study with frequency ≥ 10% included anemia 21%, neutropenia 43%, thrombocytopenia 15%, and fatigue 22%. Grade ≥ 3 neuropathy occurred in 8% of pts. For all 54 pts using RECIST 1.0, CR/PR/SD/DC was 2 (4%)/20 (37%)/19 (35%)/41(76%). Ca19.9 response ≥ 90% was seen in 20/37 (54%). For all pts, median OS was 12.3 months ( 95% CI 8.6-14.5 mo); 12 and 24 mo OS was 51% and 11%, respectively. For the 37 pts with DC on GA at 8 weeks (calculated from start Rx) median OS was 13.5 mo (95% CI 10.7-15.4 mo); 12 and 24 mo OS was 55% and 16% , respectively. No statistically significant differences were seen between S and A with respect to toxicity, response or survival. Conclusions: 1) As opposed to introduction of 5FU-based CTX at the time of disease progression/prohibitive toxicity, introduction prior to that time may be at least comparable regarding both toxicity and OS. 2) This approach may further enhance OS in pts who achieve DC on GA at 8 weeks. 3) Neither S nor A method of 5FU-based CTX introduction following GA was clearly superior in this study. 4) How best to combine 5FU-based combination CTX following GA in mPC merits further study. Supported by the Seena Magowitz Foundation.

Activity and safety of brigatinib in ALK-rearranged non-small-cell lung cancer and other malignancies: a single-arm, open-label, phase 1/2 trial

BACKGROUND

Anaplastic lymphoma kinase (ALK) gene rearrangements are oncogenic drivers of non-small-cell lung cancer (NSCLC). Brigatinib (AP26113) is an investigational ALK inhibitor with potent preclinical activity against ALK mutants resistant to crizotinib and other ALK inhibitors. We aimed to assess brigatinib in patients with advanced malignancies, particularly ALK-rearranged NSCLC.

METHODS

In this ongoing, single-arm, open-label, phase 1/2 trial, we recruited patients from nine academic hospitals or cancer centres in the USA and Spain. Eligible patients were at least 18 years of age and had advanced malignancies, including ALK-rearranged NSCLC, and disease that was refractory to available therapies or for which no curative treatments existed. In the initial dose-escalation phase 1 stage of the trial, patients received oral brigatinib at total daily doses of 30-300 mg (according to a standard 3 + 3 design). The phase 1 primary endpoint was establishment of the recommended phase 2 dose. In the phase 2 expansion stage, we assessed three oral once-daily regimens: 90 mg, 180 mg, and 180 mg with a 7 day lead-in at 90 mg; one patient received 90 mg twice daily. We enrolled patients in phase 2 into five cohorts: ALK inhibitor-naive ALK-rearranged NSCLC (cohort 1), crizotinib-treated ALK-rearranged NSCLC (cohort 2), EGFR^T790M-positive NSCLC and resistance to one previous EGFR tyrosine kinase inhibitor (cohort 3), other cancers with abnormalities in brigatinib targets (cohort 4), and crizotinib-naive or crizotinib-treated ALK-rearranged NSCLC with active, measurable, intracranial CNS metastases (cohort 5). The phase 2 primary endpoint was the proportion of patients with an objective response. Safety and activity of brigatinib were analysed in all patients in both phases of the trial who had received at least one dose of treatment. This trial is registered with ClinicalTrials.gov, number NCT01449461.

FINDINGS

Between Sept 20, 2011, and July 8, 2014, we enrolled 137 patients (79 [58%] with ALK-rearranged NSCLC), all of whom were treated. Dose-limiting toxicities observed during dose escalation included grade 3 increased alanine aminotransferase (240 mg daily) and grade 4 dyspnoea (300 mg daily). We initially chose a dose of 180 mg once daily as the recommended phase 2 dose; however, we also assessed two additional regimens (90 mg once daily and 180 mg once daily with a 7 day lead-in at 90 mg) in the phase 2 stage. four (100% [95% CI 40-100]) of four patients in cohort 1 had an objective response, 31 (74% [58-86]) of 42 did in cohort 2, none (of one) did in cohort 3, three (17% [4-41]) of 18 did in cohort 4, and five (83% [36-100]) of six did in cohort 5. 51 (72% [60-82]) of 71 patients with ALK-rearranged NSCLC with previous crizotinib treatment had an objective response (44 [62% (50-73)] had a confirmed objective response). All eight crizotinib-naive patients with ALK-rearranged NSCLC had a confirmed objective response (100% [63-100]). Three (50% [95% CI 12-88]) of six patients in cohort 5 had an intracranial response. The most common grade 3-4 treatment-emergent adverse events across all doses were increased lipase concentration (12 [9%] of 137), dyspnoea (eight [6%]), and hypertension (seven [5%]). Serious treatment-emergent adverse events (excluding neoplasm progression) reported in at least 5% of all patients were dyspnoea (ten [7%]), pneumonia (nine [7%]), and hypoxia (seven [5%]). 16 (12%) patients died during treatment or within 31 days of the last dose of brigatinib, including eight patients who died from neoplasm progression.

INTERPRETATION

Brigatinib shows promising clinical activity and has an acceptable safety profile in patients with crizotinib-treated and crizotinib-naive ALK-rearranged NSCLC. These results support its further development as a potential new treatment option for patients with advanced ALK-rearranged NSCLC. A randomised phase 2 trial in patients with crizotinib-resistant ALK-rearranged NSCLC is prospectively assessing the safety and efficacy of two regimens assessed in the phase 2 portion of this trial (90 mg once daily and 180 mg once daily with a 7 day lead-in at 90 mg).

FUNDING

ARIAD Pharmaceuticals.

Evaluating the Utility of a 'N-of-1' Precision Cancer Medicine Strategy: The Case for 'Time-to-Subsequent-Disease Progression'

It is increasingly recognized that cancer is a highly heterogeneous group of illnesses even within a particular organ site (e.g., breast, lung, colon, etc.). This observation presents a serious challenge to the traditional concept of phase 3 randomized trials designed to define therapeutic efficacy of a novel treatment strategy. For while 10% of the patients with a common malignancy (e.g., non-small-cell lung cancer) may be sufficient to consider such an effort, enrolling a sufficient number of patients into a clinical trial in a timely manner to define clinical utility would be extremely difficult if the population in question represented only 1% of this population, and essentially impossible if one wished to explore the benefits of treatment in a rarer neoplasm (e.g. ovarian cancer). Therefore, in the new era of precision cancer medicine, alternative research designs are imperative. One option would be to compare the time-to-disease progression of an individual cancer patient following treatment with a novel therapeutic to the time-to-disease progression for that specific patient on her/his immediately preceding treatment. The rationale for this strategy and early experience with this innovative approach to evaluating the efficacy of anticancer therapy is highlighted in this report.

Phase I Study of PSMA-Targeted Docetaxel-Containing Nanoparticle BIND-014 in Patients with Advanced Solid Tumors

PURPOSE

First-in-human phase I trial to determine the safety, pharmacokinetics, and antitumor activity of BIND-014, a novel, tumor prostate-specific membrane antigen (PSMA)-targeted nanoparticle, containing docetaxel.

EXPERIMENTAL DESIGN

Patients with advanced solid tumors received BIND-014 every three weeks (n = 28) or weekly (n = 27), with dose levels ranging from 3.5 to 75 mg/m(2) and 15 to 45 mg/m(2), respectively.

RESULTS

BIND-014 was generally well tolerated, with no unexpected toxicities. The most common drug-related toxicities (>20% of patients) on either schedule included neutropenia, fatigue, anemia, alopecia, and diarrhea. BIND-014 demonstrated a dose-linear pharmacokinetic profile, distinct from docetaxel, with prolonged persistence of docetaxel-encapsulated circulating nanoparticles. Of the 52 patients evaluable for response, one had a complete response (cervical cancer on the every three week schedule) and five had partial responses (ampullary adenocarcinoma, non-small cell lung, and prostate cancers on the every-three-week schedule, and breast and gastroesophageal cancers on the weekly schedule). Responses were noted in both PSMA-detectable and -undetectable tumors.

CONCLUSIONS

BIND-014 was generally well tolerated, with predictable and manageable toxicity and a unique pharmacokinetic profile compared with conventional docetaxel. Clinical activity was noted in multiple tumor types. The recommended phase II dose of BIND-014 is 60 mg/m(2) every three weeks or 40 mg/m(2) weekly. Clin Cancer Res; 22(13); 3157-63. ©2016 AACR.

Abstract A50: Phase Ib/II study of pembrolizumab plus chemotherapy: Initial results of metastatic cancer patients

Background: A selective anti-PD-1 antibody, pembrolizumab (P), blocks the interaction between programmed death-1 (PD-1) on T-cells and PD-L1 and PD-L2 on tumor cells. We report safety and clinical activity of P combined with chemotherapy in patients with metastatic cancer (NCT02331251).

Methods: Patients (pts) with confirmed metastatic solid tumors were treated with P 2 mg/kg on day 1 every 21 day cycle on 1 of 6 different arms: gemcitabine (G) on days 1 and 8, G on days 1 and 8 + docetaxel (D) on day 8, G + nab-paclitaxel (NP) on days 1 and 8, G + vinorelbine (V) on days 1 and 8, irinotecan (I) on day 1, or liposomal doxorubicin (LD) on day 1 until progression or toxicity. Eligibility included ≥1 measurable tumor lesion, Karnofsky Performance Status (KPS) of ≥70%, and adequate organ function. Tumors were assessed every 3 cycles using RECIST 1.1 and immune-related response criteria and best overall response (BOR) was evaluated.

Results: 37 pts have been enrolled at the time of submission (Table I). Median age was 55 (range 33-74) and median KPS was 80%. 3 patients (2 sarcoma, 1 ER+ breast cancer) had history of gemcitabine exposure before dosing on the G+V arm, and 2 patients with NSCLC had prior exposure to nivolumab for ≥ 2 months. The maximum tolerated dose (MTD) was exceeded for arms 3, 4, and 5 (Table I), and arm 3 dosing was subsequently divided into chemo naïve (arm 3a) and previously treated (arm 3b) PDAC pts.

Any grade drug-related treatment adverse events (AEs) occurred in 95% of patients; the most common (>10% pts) were skin rash, fatigue, diarrhea, anorexia, neutropenia, anemia, thrombocytopenia, and extremity edema. 1 infusion-related reaction was observed, related to LD. 24 patients are currently evaluable for BOR, 10 are still too early to evaluate. One PDAC pt is on G+NP for 8+ months with PR. Two SCLC pts continue on I for 7+ months with PR. 1 sarcoma pts continue on LD for 3+ and 6+ months with SD.

Conclusions: In pts with metastatic cancer, P plus chemotherapy appears to be safe. P plus G phase 2 has begun enrolling TNBC pts. We anticipate confirmation of the recommended phase 2 dose for ∼3 of the 6 arms by the time of the conference.

Cohort detailsArm# of pts (cancer type)# DLTs (type)Current dose level (all arms: P 2 mg/kg on day 1 plus):Phase 2 dose open?BOR (duration in months) for evaluable pts17 (3 ER+ breast cancer [BC], 2 triple negative BC [TNBC], 1 small cell lung cancer [SCLC], 1 cervical cancer)1 (gr3 neutropenia)G 1000 mg/m2 on days 1 and 8Yes6 PD, 1 too early21 (EGFR/KRAS/ALK wildtype [WT] lung adenocarcinoma [NSCLC]NoneG 900 mg/m2 on days 1 and 8 + D 75 mg/m2 on day 8No1 too early3a (chemo naïve pts)2 (pancreatic adenocarcinoma [PDAC])NoneG 1000 mg/m2 + NP 125 mg/m2 on days 1 and 8No1 PR (8+), 1 too early3b (previously treated pts)3 PDAC2 (gr3 thrombocytopenia and gr3 fatigue and thrombocytopenia)G 800 mg/m2 + NP 100 mg/m2 on days 1 and 8No2 SD (5, 6), 1 too early48 (3 sarcoma, 2 ER+ BC, 1 ER/HER+ BC, 1 TNBC, 1 WT NSCLC)2 (gr3 hypoxia and gr3 neutropenia)G 800 mg/m2 + V 20 mg/m2 on days 1 and 8No2 SD (2+, 3), 3 PD, 2 too early59 (3 SCLC, 3 KRAS+ NSCLC, 2 EGFR+ NSCLC, 1 WT NSCLC)3 (gr3 fatigue, gr3 nausea and vomiting, gr3 rash and papilledema)I 250 mg/m2 on day 1No2 PR (7+, 7+), 1 SD (4+), 3 PD, 2 too early67 (3 sarcoma, 2 ovarian cancer, 1 endometrial cancer, 1 ER+ BC)NoneLD 30 mg/m2 on day 1No3 SD (3, 3+ 6+), 1 PD, 3 too early

Citation Format: Glen J. Weiss, Marci Pierog, Lisa Blaydorn, Ashish Sangal, Jiaxin Niu, John H. Farley, Vivek Khemka. Phase Ib/II study of pembrolizumab plus chemotherapy: Initial results of metastatic cancer patients. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A50.

Targeting Human Cancer by a Glycosaminoglycan Binding Malaria Protein

Plasmodium falciparum engineer infected erythrocytes to present the malarial protein, VAR2CSA, which binds a distinct type chondroitin sulfate (CS) exclusively expressed in the placenta. Here, we show that the same CS modification is present on a high proportion of malignant cells and that it can be specifically targeted by recombinant VAR2CSA (rVAR2). In tumors, placental-like CS chains are linked to a limited repertoire of cancer-associated proteoglycans including CD44 and CSPG4. The rVAR2 protein localizes to tumors in vivo and rVAR2 fused to diphtheria toxin or conjugated to hemiasterlin compounds strongly inhibits in vivo tumor cell growth and metastasis. Our data demonstrate how an evolutionarily refined parasite-derived protein can be exploited to target a common, but complex, malignancy-associated glycosaminoglycan modification.

Abstract 624: Evaluation and comparison of two commercially available targeted NGS platforms to assist oncology decision making

Background: It is widely acknowledged that there is value in examining cancers for genomic aberrations via Next-Generation Sequencing (NGS) on formalin-fixed paraffin-embedded (FFPE) tumor tissue. How commercially available NGS platforms compare with each other and the clinical utility of the reported actionable results is not well known. During the course of the study, the Foundation One (F1) test generated data on a combination of somatic mutations, indels, chromosomal abnormalities, and DNA copy number changes at ∼250X coverage, while the PCDx test generated the same type of data at >5,000X coverage plus provided mRNA expression levels. We sought to compare and evaluate paired FFPE tumor using these two platforms.

Methods: Paired FFPE blocks from patients were submitted to both vendors for NGS analysis. Samples were from patients with advanced solid tumors. Patients either had a cancer type for which no standard of care exists or had progression on >1 line of systemic therapy. Turnaround time (TAT) was calculated (calendar days between the date sample received at the vendor to time of first NGS report). A biomarker was considered actionable if it has a published association with treatment response in humans. The assay report was assigned the highest of the following categories based on the list of actionable biomarker(s): commercially available drug (CA) (highest), clinical trial drug (CT), or neither option (NO) (lowest).

Results: There were 10M:11F; median age was 56 (range 35-65). The most common cancer types were 7 thoracic, 4 GI, and 3 GU. Paired F1 and PCDx results for 21 unique patient tumors submitted between 3/2014 and 9/2014 were available. Due to insufficient archival tissue from the same collection period, 1 case used samples from different collections. PCDx reported first results faster than F1 in 20 cases. When received at both vendors on the same day, PCDX reported first results for 14 of 15 cases, with a median TAT of 9 days earlier than F1 (range -7 to 14 days). PCDx and F1 reported a CA 6 and 5 times, CT 4 and 4 times, and NO 11 and 12 times; respectively. PCDx provided higher ranking actionable targets for 5 cases vs. 3 cases for F1; the rest had equivalent ranking.

Conclusions: In this analysis, commercially available NGS platforms provided clinically relevant actionable targets (CA or CT) in ∼45% of diverse cancer types. PCDx outperformed F1 in TAT and clinically relevant higher ranking of actionable targets.

Citation Format: Glen J. Weiss, Brandi R. Hoff, Robert P. Whitehead, Ashish Sangal, Susan A. Gingrich, Vivek Khemka. Evaluation and comparison of two commercially available targeted NGS platforms to assist oncology decision making. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 624. doi:10.1158/1538-7445.AM2015-624

Structure-Guided Blockade of CSF1R Kinase in Tenosynovial Giant-Cell Tumor

BACKGROUND

Expression of the colony-stimulating factor 1 (CSF1) gene is elevated in most tenosynovial giant-cell tumors. This observation has led to the discovery and clinical development of therapy targeting the CSF1 receptor (CSF1R).

METHODS

Using x-ray co-crystallography to guide our drug-discovery research, we generated a potent, selective CSF1R inhibitor, PLX3397, that traps the kinase in the autoinhibited conformation. We then conducted a multicenter, phase 1 trial in two parts to analyze this compound. In the first part, we evaluated escalations in the dose of PLX3397 that was administered orally in patients with solid tumors (dose-escalation study). In the second part, we evaluated PLX3397 at the chosen phase 2 dose in an extension cohort of patients with tenosynovial giant-cell tumors (extension study). Pharmacokinetic and tumor responses in the enrolled patients were assessed, and CSF1 in situ hybridization was performed to confirm the mechanism of action of PLX3397 and that the pattern of CSF1 expression was consistent with the pathological features of tenosynovial giant-cell tumor.

RESULTS

A total of 41 patients were enrolled in the dose-escalation study, and an additional 23 patients were enrolled in the extension study. The chosen phase 2 dose of PLX3397 was 1000 mg per day. In the extension study, 12 patients with tenosynovial giant-cell tumors had a partial response and 7 patients had stable disease. Responses usually occurred within the first 4 months of treatment, and the median duration of response exceeded 8 months. The most common adverse events included fatigue, change in hair color, nausea, dysgeusia, and periorbital edema; adverse events rarely led to discontinuation of treatment.

CONCLUSIONS

Treatment of tenosynovial giant-cell tumors with PLX3397 resulted in a prolonged regression in tumor volume in most patients. (Funded by Plexxikon; ClinicalTrials.gov number, NCT01004861.).