A First-In-Man Phase I and Pharmacokinetic Study on CHR-2797 (Tosedostat),An Inhibitor of M1 Aminopeptidases, in Patients with Advanced Solid Tumors Alison H.M

Published OnlineFirst July 28, 2009; DOI: 10.1158/1078-0432.CCR-09-0306 Published Online First on July 28, 2009 as 10.1158/1078-0432.CCR-09-0306 Cancer Therapy: Clinical

A First-in-Man Phase I and Pharmacokinetic Study on CHR-2797 (Tosedostat),an Inhibitor of M1 Aminopeptidases, in Patients with Advanced Solid Tumors Alison H.M. Reid,1,2 Andrew Protheroe,3 Gerhardt Attard,1,2 Nikki Hayward,3 Laura Vidal,1 James Spicer,1 Heather M. Shaw,1 Elizabeth A. Bone,4 Joanne Carter,4 Leon Hooftman,4 Adrian Harris,3 and Johann S. De Bono1,2

Abstract Purpose: To determine the maximum tolerated dose, dose-limiting toxicity, pharmacokinetics, and preliminary therapeutic activity profile of CHR-2797 (tosedostat), a novel, orally bioavailable inhibitor of the M1 family of aminopeptidases with antiproliferative and antiangiogenic activity in vitro. Experimental Design: A phase I study of accelerated titration design that escalated through nine doses (10-320 mg) in patients (Eastern Cooperative Oncology Group performance status, ≤2) with advanced solid tumors. CHR-2797 was administered once daily. Results: Forty patients (median age, 60 years; range, 24-80 years; male, 27; female, 13) were treated in 12 cohorts with once daily doses (10-320 mg). Dose-limiting toxicities were thrombocytopenia, dizziness, and visual abnormalities in one patient, and anemia, blurred vision, and vomiting in a second patient at 320 mg, resulting in an inability to complete 28 days of study drug. The most commonly observed toxicities were fatigue, diarrhea, peripheral edema, nausea, dizziness, and constipation. One patient had a partial response (renal cell carcinoma) and four patients had stable disease for >6 months. CHR-2797 and its active metabolite, CHR-79888, show dose-proportional increases in plasma AUC and Cmax. The terminal half-life for CHR-2797 is ∼1 to 3.5 hours and between 6 and 11 hours for CHR-79888. Intracellular (packed blood cells) exposure to CHR-79888 is consistent with intracellular levels that proved to be efficacious in xe- nograft models. Conclusion: CHR-2797 is well tolerated and can be safely administered at doses that result in intracellular levels of CHR-79888 that are associated with activity in preclinical models. The recommended dose for single agent therapy in solid tumors is 240 mg/d.

CHR-2797 (tosedostat) is a metalloenzyme inhibitor with peptidases, resulting in antiproliferative, proapoptotic, and anti- pleiotropic activity against a range of human cancer cells in vitro angiogenic effects.Although the most important intracellular and in vivo.Exposure of cells to the ester, CHR-2797, causes in- metalloenzyme targets for CHR-2797 have not been fully eluci- tracellular accumulation of its acid metabolite, CHR-79888, dated, there is a substantial body of evidence indicating that they which exerts a powerful inhibitory effect on intracellular amino- are likely to be members of the M1 family of aminopeptidases, for example, puromycin-sensitive aminopeptidase, leukotriene A4 hydrolase, or the M17 family member, leucine aminopeptidase (IC50 values of CHR-2797 and CHR-79888 for these amino-

1 peptidases are detailed in Fig.1A, all of which are often Authors' Affiliations: The Royal Marsden Hospital NHSFoundation Trust, – 2The Institute of Cancer Research, Sutton, Surrey, United Kingdom, 3The overexpressed in human cancers; refs.1 5).The antiproliferative Churchill Hospital, Headington, Oxford, United Kingdom, and 4Chroma effects of CHR-2797 likely depend on the simultaneous inhibi- Therapeutics Ltd., Abingdon, Oxon, United Kingdom tion of more than one intracellular aminopeptidase.The M1 Received 2/9/09; revised 4/15/09; accepted 4/30/09; published OnlineFirst 7/28/09. class of aminopeptidases plays a critical role in the final steps Grant support: Chroma Therapeutics. of protein recycling downstream of proteasomal degradation The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in (6), and inhibition of aminopeptidases by CHR-2797 and/or accordance with 18 U.S.C. Section 1734 solely to indicate this fact. CHR-79888 may, like proteasome inhibition, disrupt the turn- Note: Previously presented in abstract form at the 2006 ASCO and ESMO over of cell cycle intermediates, affecting cancer cell survival or annual meetings and in an oral presentation at 2007 ASCO annual meeting proliferation (Fig.1B). Requests for reprints: Johann S. de Bono, The Royal Marsden NHS Foun- In addition, inhibition of aminopeptidases by CHR-2797 and dation Trust, Downs Road, Sutton, Surrey SM2 5PT, United Kingdom. its metabolite in transformed cells of the hematopoietic lineage Phone: 44-20-8722-4302; Fax: 44-20-8642-7979; E-mail: [email protected]. F 2009 American Association for Cancer Research. seems to lead to an accumulation of small peptides and results doi:10.1158/1078-0432.CCR-09-0306 in a deficiency of free amino acids for new protein synthesis (1).

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Phase I Trial of CHR-2797 (Tosedostat)

Patients and Methods Translational Relevance Patient eligibility. Patients with the age of ≥18 y with histologically CHR-2797 (tosedostat) is a metalloenzyme inhibi- or cytologically confirmed advanced solid malignancies refractory to tor with pleiotropic activity against a range of hu- conventional treatment were enrolled.Eligibility criteria included life man cancer cells in vitro and in vivo. It has shown expectancy of ≥12 wk, Eastern Cooperative Oncology Group perfor- an inhibitory effect on intracellular aminopepti- mance status of ≤2, no previous anticancer therapy within 4 wk of study dases, resulting in antiproliferative, proapoptotic, entry (6 wk for mitomycin and nitrosureas), and adequate hematopoi- 9 9 and antiangiogenic effects. We describe here the etic (absolute neutrophil count, ≥1.5 × 10 /L; platelets, ≥100 × 10 /L), ≤ first-in-man phase I dose-escalation study of CHR- hepatic (bilirubin, 1.5 × upper normal limit; aspartate aminotransfer- ≤ 2797 to define the safety, tolerability, and maximum ase (AST)/alanine aminotransferase (ALT), 2.5 × upper normal limit or ≤5 × upper normal limit in the presence of liver metastases), and tolerateddosewhenadministeredorallydailyto renal function (creatinine, ≤1.5 × upper normal limit). Patients with patients with advanced solid tumors. Secondary ob- known brain tumors or brain metastases and patients who had not re- jectives were to assess pharmacokinetic variables covered from acute adverse effects of previous therapies were excluded. of CHR-2797 and make a preliminary assessment The local research ethics committees at both participating centers ap- of antitumor activity. This study will inform the fu- proved the study protocol, and written informed consent was obtained ture administration and development of this agent from all patients before any study-related procedures. in solid tumors. CHR-2797 is currently showing Study design and dose-escalation schedule. This was an open-label, encouraging activity in phase II trials for patients nonrandomized, phase I dose-escalation study of accelerated titration with hematologic malignancies. design (13).CHR-2797 capsules (5, 10, 20, and 40 mg) were taken orally daily after food at the same time each day.The study involved three distinct phases for evaluation of dose: (a) a fixed dose with in- creasing duration, (b) dose escalation over a fixed duration, and (c) an expansion of the recommended dose level to a maximum of 12 pa- This conclusion is inferred from the induction of a cellular tients.The starting dose for cohort one was 10 mg, administered as a single dose for seven consecutive days, followed by a 21-d rest period. stress response known as the amino acid deprivation response Assuming that patients in cohort 1 tolerated 7 d of dosing, patients in (7).One of the consequences of the amino acid deprivation cohorts 2, 3, and 4 would also be treated with 10 mg once daily but for response is the up-regulation of proapoptotic proteins such as 14, 21, and 28 d, respectively.If no NCI-Common Terminal Criteria for CHOP and Noxa (1, 8), which serve to prime the cell for apo- Adverse Events (CTCAE) version 3 grade 2 toxicity was seen in the first ptosis.It is not currently entirely clear why transformed cells are phase and safety of 28-d continuous dosing was shown, the study more sensitive to amino acid deprivation than normal cells, but would continue into the second phase, in which doses were increased this disparity in sensitivity is also noted with other types of cell according to an accelerated titration design.Cohorts consisted of one stress (9).Indeed, it has been known for some time that tumor patient each, and permitted dose increments were of 100% until grade cells are critically dependent on specific amino acids, for exam- 2 toxicity was observed.Patients received 28 d of therapy before a new patient could start study drug at an increased dose level.Once drug- ple, arginine, for their survival.Depletion of intracellular related grade 2 toxicity was documented, the design required a minimum arginine has more profound effects on transformed than of three patients to receive at least 28 d of treatment in subsequent normal cells, which correlates well with the effects of CHR- cohorts, and dose increments of 25% to 40% were used.When cohorts 2797 (10, 11).Aminopeptidase inhibition also reduces phos- included three or more subjects, 14 d of treatment had to be completed phorylation of mTOR substrates and rates of protein synthesis, before the next two subjects were enrolled.No intrapatient dose escala- both indicative of amino acid depletion (1).Natural product tion was permitted. inhibitors of aminopeptidases, particularly bestatin, exhibit Definition of maximum tolerated dose and dose-limiting toxicity. The similar, albeit weaker, pharmacologic actions to CHR-2797, in- maximum tolerated dose was defined as the dose level below which cluding its proapoptotic, antiproliferative, and antiangiogenic more than one of three or two of six patients developed grade 3 to 4 tox- effects, and its ability to induce amino acid deprivation re- icity or dose-limiting toxicity.Dose-limiting toxicity was defined as any of the following events that was determined to be possibly or probably sponse–related gene expression changes (1).Bestatin has related to CHR-2797 and occurred during the first course (28 d) of treat- an IC50 against puromycin-sensitive aminopeptidase of 400 ment: absolute neutrophil count of <0.5 × 109/L (lasting for >5 d or with nmol/L but, as a charged molecule, is relatively weak in cell- sepsis), platelet count of <25 × 109/L, grade 2 or above neurotoxicity/ based systems such as proliferation assays.Bestatin is approved cardiotoxicity, any drug-related, nonhematologic grade 3 to 4 toxicity, in Japan as a maintenance therapy in patients with nonlym- and the inability to tolerate 28 d of daily oral therapy due to toxicity. phocytic leukemia and has been shown to improve overall Dose modification due to toxicity. Any patient in whom a dose- survival in a phase III double blind placebo-controlled neo- limiting toxicity occurred during the course of treatment was to have adjuvant trial in stage I to II squamous cell lung carcinoma treatment withheld until toxicity resolved to baseline or grade 1 or (12).CHR-2797 is considerably more potent than bestatin in better.Upon resolution, therapy could be reinstituted at the next lower dose level.The granulocyte count and platelet count had to be >1.5× preclinical studies, showing 300 to 1000 times greater inhibi- 9 9 tion of cell proliferation as measured by [3H]thymidine incor- 10 /L and >100 × 10 /L, respectively, for further dosing.Drug-induced nonhematologic toxicities had to have improved to grade ≤ 1 before poration in a selection of cell lines (1). re-treatment.Treatment could be delayed for up to 2 wk to allow suf- We therefore conducted a phase I dose-escalation study to deficient time for recovery from toxicities.If the hematologic or nonhe- fine the safety, tolerability, and maximum tolerated dose of matologic toxicities had not resolved within 2 wk, the patient was CHR-2797 when administered orally daily to patients with ad- considered to have a dose-limiting toxicity and was discontinued from vanced solid tumors.Secondary objectives were to assess the the study. pharmacokinetic variables of CHR-2797 and make a prelimi- Patient evaluation and follow-up. Toxicity assessment, hematology, nary assessment of antitumor activity. and clinical biochemistry were done at baseline and weekly during

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Cancer Therapy: Clinical the study.Full physical and Eastern Cooperative Oncology Group Pharmacokinetic assessments. Pharmacokinetic analyses included performance status were recorded at each month of therapy.The initial measurements of CHR-2797 and CHR-79888 concentrations in plas- study period was 28 d.If, in the opinion of the investigator, treatment ma and, intracellularly, in packed blood cells (i.e., combined red and for longer than this time might be beneficial, it could be extended at white cells) on all patients.Blood samples (2 × 3 mL) were taken the same daily dose until progressive disease or unacceptable toxicity. at baseline and at 30 and 60 min and 2, 4, 6, 8, 24, and 48 h post Response was evaluated according to the Response Evaluation Criteria first dose.Pharmacokinetic samples were taken up to 24 h after in Solid Tumors 1 (14) at 28 d and subsequently every 1 or 2 mo.Ra- thelastdoseincycle1[i.e.,D7(cohort1),D14(cohort2),D21 diologic responses were confirmed by repeat imaging done after an in- (cohort 3), and D28 (all subsequent cohorts)].All patients had phar- terval of at least 28 d.Patients were taken off study upon disease macokinetic blood samples taken at the end of each monthly cycle up to the end of the third month.Pharmacokinetic parameters were progression, unacceptable toxicity, investigator discretion, serious viola- calculated using the WinNonlin Professional software (version 4.1; tion of protocol, or at their own request.Following a serious adverse Pharsight Corporation).No pharmacodynamic assay for aminopepti- event of thrombotic thrombocytopenic purpura/hemolytic uremic dase inhibition or downstream effect was available for this first syndrome, subsequent patients underwent serial ADAMTS-13 function- clinical dose finding trial of CHR-2797, and therefore, no correlations ality testing before and throughout their time on study drug until a drug could be established between the cytoreductive effect of the agent effect was ruled out.Samples were analyzed at the Haemostasis Unit, and the degree of amino-acid depletion in cells.Once the daily University College, London. dose had escalated to ≥40 mg, patients whose tumors were accessible

Fig. 1. A, chemical structure and aminopeptidase inhibition. From left to right, the chemical structures of the ester CHR-2797, its active metabolite CHR-79888, and the aminopeptidase inhibitor bestatin. IC50 values (nanomoles per liter) are listed for each compound for several aminopeptidases. B, mechanism of action of CHR-2797. CHR-2797 inhibits aminopeptidase activity and, as a result, seems to deplete cellular amino acid pools selectively in tumor cells. The class of aminopeptidases inhibited by CHR-2797 plays a critical role in the final steps of protein recycling downstream of proteasomal degradation. Therefore, inhibition of aminopeptidases by CHR-2797 may, like proteasome inhibition (as with bortezomib here), disrupt the turnoverof cell cycle intermediates in such a way that it affects cancer cell survival or proliferation.

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Phase I Trial of CHR-2797 (Tosedostat)

complained of grade 2 hearing loss and difficulty focusing. n Table 1. Patient characteristics [ = 40; median An MRI scan of the brain was normal. age, 60 (24-80) y] Maximum tolerated dose. Following these two dose-limiting toxicities at 320 mg, the maximum tolerated dose based on No. of patients 28 days of dosing was determined to be 240 mg/d continuous dosing, and in accordance with the protocol, nine additional Gender patients were treated at 240 mg for at least 28 days in the third Male 27 phase of the study to further evaluate the antitumor activity and Female 13 tolerability of the 240-mg dose of CHR-2797.In this expansion Eastern Cooperative Oncology Group performance status 010phase, one patient experienced grade 3 toxicity presenting with 128right upper quadrant abdominal pain and grade 3 ALT and AST 22elevations on cycle 1 day 7.This patient suffered from a congen- No. of previous chemotherapies, median (range) 2 (1-6) ital metabolic form of liver cirrhosis complicated by hepatocel- Tumor types lular carcinoma and entered the study with a grade 1 elevation Renal cell 11 Colorectal 6 of liver transaminases.CHR-2797 was discontinued, and ALT/ Lung 5 AST returned subsequently to within the reference range by cy- Prostate 3 cle 1 day 28.Drug was restarted at this point with close mon- Breast 2 itoring of the LFTs; ALT and AST following this event never Adenocarcinoma (unknown primary) 1 Bladder/transitional cell carcinoma (paraganglioma) 2 exceeded grade 1 derangement.This patient continued daily Sarcoma 3 treatment on the same dose for another 11 months without in- Liver/lower esophageal/melanoma/pancreas/ovarian/ 1 each terruption.CHR-2797 240 mg was chosen as the recommended pseudomyxoma/unknown dose for further studies. Overall safety and tolerability. In general, CHR-2797 was well tolerated.Non –dose limiting toxicities that occurred in by biopsy were offered to consent to baseline and on therapy ≥15% of patients and all grade ≥3 adverse events that occurred biopsies. in two or more patients at any time on study, regardless of relationship to drug, are listed in Table 3.The most common nonhematologic toxicities were fatigue, diarrhea, peripheral Results edema, nausea, dizziness, and constipation.Diarrhea and nausea were usually self-limiting and easily managed with anti- General trial conduct. Between October 2004 and February diarrheal/antiemetic agents as required.Grade 2 dizziness was 2007, 40 patients received 107 cycles of CHR-2797 in 12 a feature of one of the dose-limiting toxicities at 320 mg, which cohorts across nine dose levels.Patient demographics resolved on discontinuation of the study drug.A further 12 pa- are detailed in Table 1 and study design in Table 2.Patients tients complained of grade 1 dizziness, which was self-limiting were treated in cohorts of one patient until the 40-mg cohort and did not necessitate study drug discontinuation.In addition (second phase), which was expanded to three patients as to the patient on 240 mg CHR-2797 described earlier, two the first patient developed reversible grade 2 ALT elevation. Overall, minimal toxicity was observed at the first five dose levels (10-90 mg; Table 3).The maximum tolerated dose was declared at 240 mg as two patients experienced dose-limiting Table 2. Dose escalation schedule and dose- toxicity at the 320-mg dose. limiting toxicities Dose-limiting toxicities. Dose-limiting toxicities were reported in two of four patients at 320 mg because of a com- Dose No. of No. of DLTs patients (in first 28 d) bination of thrombocytopenia, dizziness, and visual abnormalities in one patient, and anemia, blurred vision, First phase and vomiting in a second patient, leading to the patients be- 10 mg (for 7, 14, 21, 28 d) 1 each 0 ing unable to complete 28 days of daily oral therapy.The Second phase first dose-limiting toxicity patient was a 74-year-old female 20 mg 1 0 40 mg 3 0 with pseudomyxoma peritonei, who presented with grade 2 60 mg 3 0 dizziness on day 10 of cycle 1.Hematology revealed a grade 90 mg 3 0 2 drop in hemoglobin and platelets.She had also experi- 130 mg 5 0 enced grade 1 visual disturbance.The drug was stopped, 180 mg 3 0 240 mg 4 0 and all symptoms and hematologic abnormalities recovered. 320 mg 4 2 Neurologic examination was normal throughout, and a mag- Third phase netic resonance imaging (MRI) scan of the brain showed no 240 mg 10* 1† abnormality.The second patient, a 69-year-old female with a solitary fibrous lung carcinoma with pleural metastases, had Abbreviation: DLTs, dose-limiting toxicities. an episode of vasovagal syncope on day 5 of cycle 1.Hema- *Two patients reduced to 180 mg at 7 and 12 weeks due to toxicity (grade 3 diarrhea and grade 3 facial flushing, respectively). tology revealed a grade 3 drop in hemoglobin.The patient †This patient was in the cohort expansion and therefore is not a was transfused, study drug was discontinued, and her hemo- true dose-limiting toxicity. globin levels remained stable thereafter.This patient also

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Cancer Therapy: Clinical

Table 3. Adverse events (regardless of relationship to drug) in ≥15% of patients and all grade 3 and 4 adverse events in two or more patients

Adverse event No. of pts Dose 10-90 mg Dose 130 mg Dose 180 mg Dose 240 mg* Dose 320 mg (n =14) (n =5) (n =3) (n =14) (n =4) G1-2 G3 G1-2 G3 G1-2 G3 G1-2 G3 G1-2 G3

Fatigue 20 3 1 1 2129 010 Diarrhea 18 4 0 1 0216 130 Peripheral edema 18 5 0 1 0208 020 Nausea 14 1 0 2 0305 030 Dizziness 13 2 0 1 0206 020 Constipation 12 2 0 1 0205 020 Anemia 111 100106 020 Vomiting 10 0 0 1 0105 030 Abdominal pain 10 1 0 1 0115 010 Headache 9 3 0 2 0002 020 AST increase 8 2 0 0 0101 400 Rash 8 1 000006 010 Dyspnea 7 2 0 0 1201 000 Thrombocytopenia 6 2 0 0 0002 010 Anorexia 6 2 0 1 0011 010 Hot flushes 6 1 0 0 0202 010 ALT increase 6 2 0 1 0100 200 Visual disturbance 5 3 0 0 0000 020 Insomnia 5 1 0 0 0102 010 Hyponatremia 4 0 1 0 0000 300 LRTI 4 0 111100 000

Abbreviations: pts, patients; LRTI, lower respiratory tract infection. *Grade 4 dyspnea in one patient and grade 4 thrombocytopenia in one patient at 240-mg dose.

further patients (on 40 and 240 mg) experienced a grade 2 and There did not seem to be any discernible influence of this 3 elevation of transaminases, respectively, both in the first week agent on the metalloenzyme ADAMTS13, and blood films of of treatment.Dechallenge and rechallenge of study drug re- patients were normal. vealed a probable drug relationship in the patient with the Pharmacokinetics. The pharmacokinetics of CHR-2797 and grade 3 increase, but LFTs never exceeded grade 1 on rechal- the active metabolite, CHR-79888, in plasma and packed blood lenge.There was no recurrence of transaminase derangement cells were measured on days 1 and 28, and selected variables are in the patient with grade 2 increase on drug rechallenge.Other shown in Fig.2.For doses up to 240-mg exposure to CHR-2797 liver indices were not seen to increase in the first 28 days. and CHR-79888 on day 1 increased in an approximately dose- Less commonly, hematologic toxicity was considered possi- proportional manner in plasma and packed blood cells.On bly related to study drug, with some patients experiencing ane- day 28, exposure to CHR-2797 was dose proportional, as was mia and thrombocytopenia.Anemia was predominantly grade CHR-79888 in plasma, but intracellular exposure to CHR- 1 to 2, except for one patient who suffered grade 3 (a dose- 79888 was sub–dose proportional.Exposure to CHR-2797 and limiting toxicity).There seemed to be a dose-dependent reduc- CHR-79888 was generally higher in the plasma than in the tion in platelets, which was first observed between days 7 and packed blood cells across the entire dose range on days 1 and 21.This rarely led to thrombocytopenia [five patients had grade 28, with the exception of CHR-79888 at doses 10 to 40 mg on 1-2 thrombocytopenia and one patient (discussed below) had day 28.Overall, exposure to CHR-79888 was higher than that grade 4]. for CHR-2797 on days 1 and 28 in plasma and packed blood One patient with advanced nonalveolar fibrosarcoma with cells.The pharmacokinetic results indicate that there is no accu- extensive lung involvement, who had been treated with mulation of CHR-2797 in plasma or packed cells following re- 90 mg CHR-2797 for >2 months without incident, developed peat dosing for 28 days.Exposure to CHR-79888 in packed thrombotic thrombocytopenic purpura/hemolytic uremic syn- blood cells on day 28 is higher than on day 1, across the entire drome and died 3 weeks later.The underlying cause of the dose range, and in plasma samples up to 40 mg dose.The termi- thrombotic thrombocytopenic purpura was never elucidated, nal elimination half-life for plasma CHR-2797 was relatively and ADAMTS-13 testing to examine the functionality of the short, ~1 to 3.5 hours, whereas the half-life for CHR-79888 von Willebrand factor-cleaving protease was within normal was considerably longer at ~6 to 11 hours (day 28 values).There limits.This event was ultimately felt unlikely to be related was no correlation between AUC0-t/dose versus weight or body to study drug.However, for safety reasons, ongoing and new surface area (Fig.2), which supported fixed drug dosing.In ani- patients treated with CHR-2797 subsequent to this event un- mal model studies in which significant inhibition of tumor derwent serial ADAMTS-13 testing before and throughout growth was observed, the levels of CHR-79888 in tumors (250- their time on study drug.No association between drug treat- 750 ng/mL) 24 hours after the last dose of CHR-2797 were com- ment and reduced ADAMTS-13 functionality was reported. parable with the steady state levels of CHR-79888 (250 ng/mL) in

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Phase I Trial of CHR-2797 (Tosedostat) packed cells from patients dosed at ≥130 mg and to the intratu- non–small cell lung carcinoma (90 mg; 6 months).The median moral levels of CHR-79888 measured in resected metastatic skin duration on study for each patient is depicted in Fig.3C. lesions (500 ng/mL) of a renal cell carcinoma patient on 130 mg of CHR-2797, who achieved a partial response. Antitumor activity. A patient with metastatic renal cell carci- Discussion noma achieved a confirmed partial response at 84 days, which was maintained for a further 112 days (Fig.3A and B).Of the We describe here the results of a first-in-man phase I study of 16 patients with reported stable disease on day 28, seven met CHR-2797, an orally bioavailable aminopeptidase inhibitor Response Evaluation Criteria in Solid Tumors criteria for stable with antiproliferative activity ~300 times more potent in vitro disease 3 months later, with doses of CHR-2797 ranging from than the natural product aminopeptidase inhibitor, bestatin. 40 to 240 mg.The four patients who continued to have stable Krige et al.(1) recently published an extensive preclinical inves- disease for >6 months had the following tumor types: hepato- tigation into the proposed mechanism of action of CHR-2797, cellular cancer (240 mg; 9 months), metastatic breast cancer showing marked antiproliferative activity of CHR-2797 against (180 mg; 7.5 months), ovarian cancer (40 mg; 7 months), a wide range of tumor cell lines.We now show that CHR-2797

Fig. 2. Pharmacokinetics of CHR-2797 and CHR-79888. CHR-2797 and CHR-79888 AUC values in packed blood cells (A) and plasma (B) for dose levels up to the maximum tolerated dose at days 1 and 28, following daily dosing of CHR-2797. CHR-2797 and CHR-79888 Cmax values in packed blood cells (C) and plasma (D) for dose levels up to maximum tolerated dose at days 1 and 28, following daily dosing of CHR-2797. For CHR-2797 and CHR-79888 in AUC0-t /dose versus weight per patient (E) and in AUC0-t /dose versus body surface area per patient (F).

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Cancer Therapy: Clinical

Fig. 3. Preliminary antitumor activity and duration of CHR-2797 treatment. A patient with metastatic renal cell carcinoma showed a partial response by Response Evaluation Criteria in Solid Tumors after 84 d on study drug. This response was confirmed with a repeat computed tomography scan 4 wk later. The patient remained on study for 7 mo. A, a perigastric node at baseline circled in blue and following 5.5 mo on study drug (B). The duration of CHR-2797 treatment is indicated in (C) for each patient by an individual black column. Red arrow, 6-mo time point. is safe and well tolerated up to an maximum tolerated dose of thrombocytopenia, dizziness, and visual abnormalities in one 240 mg, with preliminary evidence of antitumor activity in sol- patient, and anemia, blurred vision, and vomiting in a second id tumors.The results of this phase I study and preclinical data patient, precluding continuation with study drug at the 320-mg in leukemic cells have led to the exploration of CHR-2797 in a dose.The maximum tolerated dose was therefore declared at phase I/II study in patients with refractory/relapsed acute mye- 240 mg/d.The most common adverse events, largely grade 1 loid leukemia/myelodysplastic syndrome and multiple myelo- or 2, were fatigue, diarrhea, peripheral edema, nausea, dizzi- ma, wherein encouraging preliminary clinical activity has been ness, and constipation.Three patients had transient transamini- reported (15, 16). tis, which returned to normal on stopping the drug.On drug The principal aim of this study in solid tumor patients was to rechallenge, one patient had no recurrence, the other two pa- establish safety, maximum tolerated dose, and dose-limiting tients' transaminases did not increase above grade 1, and all toxicity.Dose-limiting toxicities included a combination of three patients continued study drug.

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Phase I Trial of CHR-2797 (Tosedostat)

One patient experienced thrombotic thrombocytopenic pur- carcinoma (9 months; 240 mg), breast cancer (7.5 months; pura, and we investigated whether, as a metalloenzyme inhibi- 180 mg), ovarian cancer (7 months; 40 mg), and NSCLC tor, CHR-2797 might directly affect ADAMTS-13 function. (6 months; 90 mg). Thrombotic thrombocytopenic purpura is associated with a Preclinical studies have shown CHR-2797 to have synergy severe deficiency of von Willebrand factor–cleaving protease with various anticancer drugs in inducing antiproliferative (17–20), now known as ADAMTS-13 metalloprotease (21). effects in vitro (1).A focus for future development of ADAMTS-13 levels were within normal limits in this patient, CHR-2797 will be to test the drug in combination with a and the incorporation of blood tests to check ADAMTS-13 range of conventional cytotoxics and specific molecular tar- functionality in all new and ongoing patients showed no geting agents, particularly antiangiogenics.A phase I study drug-related effect of CHR-2797/CHR-79888 on ADAMTS-13 on CHR-2797 with paclitaxel has recently closed accrual. activity. In vitro work examining the direct effect of CHR-2797 In conclusion, CHR-2797 (tosedostat) has shown an accept- and CHR-79888 on ADAMTS-13 activity also concluded that able safety profile for patients with advanced solid tumors there did not seem to be a direct inhibitory effect of this agent at doses up to 240 mg/d.Evidence of antitumor activity on ADAMTS-13 function.No mechanistic basis for this case of was seen in patients with a range of tumor types and phase thrombotic thrombocytopenic purpura could be established. II studies in elderly and/or treatment-refractory acute mye- There are many possible alternative causes of acquired throm- logenous leukemia patients have shown encouraging prelim- botic thrombocytopenic purpura/hemolytic uremic syndrome, inary results. particularly in the presence of a disseminated malignancy. Overall, to date >122 patients have now been treated in multi- Disclosure of Potential Conflicts of Interest ple trials with CHR-2797, either alone or in combination with paclitaxel, with no further cases of thrombotic thrombocytope- E. Bone, J. Carter, and L. Hooftman are employed by Chroma Therapeu- nic purpura–hemolytic uremic syndrome (15, 16). tics. J.S. De Bono has served as a consultant for Chroma Therapeutics. The pharmacokinetic profile confirmed that daily oral ad- Chroma Therapeutics is a spin-off company from the Institute of Cancer Research. A. Reid, G. Attard, L. Vidal, J. Spicer, H. Shaw, and J.S. De Bono ministration of CHR-2797 resulted in intracellular (packed are employed by the Institute of Cancer Research. The Institute of Cancer blood cell) levels of CHR-79888 consistent with intratumoral Research has a commercial interest in Chroma Therapeutics. levels at which anticancer activity was reported in preclinical models.Clinically meaningful antitumor activity was seen in a patient with renal cell carcinoma with a partial response Acknowledgments

(Fig.3), who remained on study for 7 months.Four other The Royal Marsden NHSFoundation Trust and the Institute of patients had confirmed stable disease by Response Evaluation Cancer Research thank the NHSfunding to the NIHR Biomedical Criteria in Solid Tumors in excess of 6 months: hepatocellular Research Centre.

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www.aacrjournals.org 4985 Clin Cancer Res 2009;15(15) August 1,2009 Downloaded from clincancerres.aacrjournals.org on September 24, 2021. © 2009 American Association for Cancer Research. Published OnlineFirst July 28, 2009; DOI: 10.1158/1078-0432.CCR-09-0306

A First-in-Man Phase I and Pharmacokinetic Study on CHR-2797 (Tosedostat), an Inhibitor of M1 Aminopeptidases, in Patients with Advanced Solid Tumors

Alison H.M. Reid, Andrew Protheroe, Gerhardt Attard, et al.

Clin Cancer Res Published OnlineFirst July 28, 2009.

Updated version Access the most recent version of this article at: doi:10.1158/1078-0432.CCR-09-0306

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