
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Cancer Therapy: Clinical |
Authors' Affiliations: 1 Princess Margaret Hospital Phase II Consortium; 2 Division of Dermatology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; 3 Bayer Pharmaceuticals Corp., West Haven, Connecticut; and 4 National Cancer Institute, Bethesda, Maryland
Requests for reprints: Lillian L. Siu, Department of Medical Oncology and Hematology, Princess Margaret Hospital, University Health Network, 610 University Avenue, Suite 5-718, Toronto, Ontario, Canada M5G 2M9. Phone: 416-946-2911; Fax: 416-946-4467; E-mail: lillian.siu{at}uhn.on.ca.
| Abstract |
|---|
|
|
|---|
Experimental Design: Sorafenib was administered alone for a 1-week run-in period, and then both drugs were given together continuously, with every 28 days considered as a cycle. Three dose levels were assessed.
Results: Seventeen patients with advanced solid tumors received 75 cycles of treatment. The most frequent adverse events of all grades were constitutional and gastrointestinal in nature followed by electrolytes and dermatologic toxicities. Fatigue was the most common adverse event (17 patients; 100%) followed by diarrhea (15 patients; 88%), hypophosphatemia (13 patients; 76%), and acneiform rash (12 patients; 71%). These adverse events were predominantly mild to moderate. The recommended phase II dose of this combination was determined as 400 mg twice daily sorafenib and 150 mg daily erlotinib. Pharmacokinetic analysis revealed no significant effect of erlotinib on the pharmacokinetic profile of sorafenib. Among 15 evaluable patients, 3 (20%) achieved a confirmed partial response and 9 (60%) had stable disease as best response.
Conclusions: Sorafenib and erlotinib are well tolerated and seem to have no pharmacokinetic interactions when administered in combination at their full single-agent recommended doses. This well tolerated combination resulted in promising activity that needs further validation in phase II studies.
The epidermal growth factor receptor (EGFR) initiates a signal transduction cascade that modulates cellular functions through activation of pathways, such as the mitogen-activated protein kinase and the phosphatidylinositol 3-kinase. The mitogen-activated protein kinase cascade relays extracellular signals from ligand-bound cell surface tyrosine kinase receptors to the nucleus by a series of phosphorylation events beginning with the activation of Ras (3, 4). Activated Ras triggers downstream effectors, including the Raf serine/threonine kinase (5–7). Activated Raf propagates signaling by phosphorylating mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 and extracellular signal-regulated kinase 1/2, inducing activation of transcription factors involved in regulation of genes critical in proliferation, angiogenesis, and resistance to cytotoxics (8–12). The mitogen-activated protein kinase pathway seems to be dysregulated in several human malignancies, and therefore, many of its critical components represent potential targets for anticancer treatment.
Erlotinib (Tarceva, OSI-774; OSI Pharmaceuticals) is an oral quinazolinamine, which blocks EGFR tyrosine kinase through competitive inhibition at the ATP-binding site (13). A phase I study showed 150 mg daily on a continuous schedule as the recommended dose for phase II studies (RPTD) and reported skin toxicity and diarrhea as dose limiting (14). Erlotinib has shown activity in some tumor types, including head and neck (15), lung (16), ovarian (17), and endometrial (18) carcinoma. Two randomized phase III trials confirmed survival benefits and have led to drug approval in non–small cell lung cancer and in combination with gemcitabine in pancreatic cancer (19, 20).
Sorafenib (Nexavar, BAY 43-9006; Bayer Pharmaceuticals Corp.) is an oral multitargeted agent with activities against Raf kinase and vascular endothelial growth factor receptor-2 (VEGFR-2), resulting in tumor growth inhibition via interference with cellular proliferation and angiogenesis. Sorafenib also exhibits median inhibitory concentrations (IC50) in nanomolar ranges for other receptor tyrosine kinases, such as VEFGR-3, platelet-derived growth factor receptor-ß, Flt-3, and c-KIT (21). Phase I studies of sorafenib determined 400 mg twice daily on a continuous schedule as the RPTD (22–25). Toxicities associated with sorafenib were mild to moderate and included rash, hand-foot syndrome, diarrhea, fatigue, and hypertension. Partial responses were observed in hepatocellular (26) and renal cell cancers (27) with single-agent sorafenib, and disease stabilization has been reported in multiple tumor types, such as melanoma, colorectal, non–small cell lung cancer, and ovarian cancer (22, 24, 25, 28–30). Recently, sorafenib has been approved for the treatment of advanced renal cell cancers.5 Recent preclinical data showed a dose-dependent synergistic effect in growth inhibition and apoptosis with the concurrent administration of sorafenib and erlotinib, providing a rationale for the clinical development of this combination (31). Yet, definitive molecular data are lacking to explain the mechanisms of synergy, and the relative contributions of the two agents to tumor growth inhibition when administered in combination are uncertain. Given that sorafenib and erlotinib have independently shown anticancer activity in the clinical setting, and the presence of in vitro synergism when combined, a phase I trial was conducted to determine the RPTD, safety, and pharmacokinetics of these two targeted agents given together on a continuous schedule.
| Materials and Methods |
|---|
|
|
|---|
18 years; (b) Eastern Cooperative Oncology Group performance status
2; (c) adequate hematologic, hepatic, and renal function (absolute neutrophil count
1.5 x 109/L, platelets
100 x 109/L, bilirubin
upper limit of normal, aspartate aminotransferase/alanine aminotransferase
2.5 x upper limit of normal, and creatinine
upper limit of normal or creatinine clearance
60 mL/min); and (d) 4-week interval between study treatment and any prior radiotherapy or chemotherapy. Exclusion criteria included (a) prior treatment with sorafenib, erlotinib, or any agents targeting EGFR, Raf, VEGF, or VEGFR; (b) major surgery within the last 21 days; (c) uncontrolled hypertension (defined as systolic blood pressure >140 mmHg and/or diastolic pressure >90 mmHg in spite of medical treatment) or intercurrent illnesses; (d) bleeding diathesis or coagulopathy; (e) brain or meningeal metastases; and (f) concurrent use of enzyme-inducing antiepileptic drugs or other CYP3A4 inducers. The institutional review board of both participating centers approved the study, which was conducted in accordance with federal and institutional guidelines.
Study design. This was a dual-agent, open-label, phase I study. Sorafenib was administered alone for a week during a "run-in" period, and then both drugs were given together on a continuous basis with every 28 days considered as a cycle. Three dose levels were planned: (a) 200 mg twice daily sorafenib and 100 mg daily erlotinib, (b) 200 mg twice daily sorafenib and 150 mg daily erlotinib, and (c) 400 mg twice daily sorafenib and 150 mg daily erlotinib. Further dose escalations were not considered because at dose level 3 both drugs would be administered at their RPTD as single agents. No intrapatient dose escalation was permitted.
Three patients were initially enrolled in each dose level, and dose escalation followed the standard 3 + 3 rule. The occurrence of dose-limiting toxicity (DLT) was monitored during the first 28 days while the two agents were given in combination. The RPTD is the dose level in which less than or equal to one of six patients encountered DLT. If the frequency of DLT encountered at the highest dose level did not fulfill the maximum tolerated dose definition, then 400 mg twice daily sorafenib with 150 mg daily erlotinib was to be accepted as the RPTD.
Toxicity was graded according to the Common Terminology Criteria for Adverse Events version 3.0. DLTs were defined as adverse events attributed as being possibly, probably, or definitely related to the study agents, occurring within the first 28 days of their coadministration and fulfilling one of the following criteria: (a) any grade 4 hematologic toxicity, (b) any nonhematologic toxicity grade
3 (except alopecia, nausea, and vomiting responsive to antiemetics or diarrhea responsive to medications), (c) any intolerable grade 2 nonhematologic or grade 3 hematologic toxicity requiring a dose reduction during the first 28 days of combination therapy, and (d) any toxicity resulting in a treatment delay of >1 week during the first 28 days of combination therapy.
Patient evaluation. Pretreatment evaluations were done within 7 days of treatment start and included history and physical examination, performance status, hematology, biochemistry, and urinalysis. Physical examinations were repeated on days 1 and 15 of each cycle, whereas laboratory evaluations were measured weekly for the entire duration of the study.
Baseline radiological investigations were done within 28 days of study start. Response was assessed by Response Evaluation Criteria in Solid Tumors (32) every other cycle and confirmed at least 4 weeks after the initial observation. All responses were independently reviewed.
Dose modifications. Patients were required to meet the following criteria to receive study drugs on day 1 of a treatment cycle: absolute neutrophil count
1.0 x 109/L, platelets
100 x 109/L, and nonhematologic toxicity recovered to grade
1 (or tolerable grade 2). If a DLT occurred in the first cycle, treatment was withheld until toxicity resolved to grade 2 or less. At the investigator's discretion depending on the nature of the adverse event, on toxicity resolution, the dose of one or both drugs could be modified. Patients in whom one study drug was held or discontinued could continue to receive the other. Subjects who failed to recover to grade 0 to 1 or tolerable grade 2 from a treatment-related adverse event within 14 days, or those who required a third dose reduction, discontinued study therapy.
Duration of the therapy. Study treatment continued until disease progression, intercurrent illness that prevented further administration of treatment, unacceptable adverse event, patient's decision to withdraw from the study, or changes in the patient's condition rendering the patient unacceptable for further treatment.
Pharmacokinetic analysis. Blood samples were collected during cycle 1 at day –6 before morning sorafenib dosing; day –2 before dose and at 1, 2, 4, 6, 8, 12, and 24 h after dose; and at the same time points on day 15. Sample analysis for sorafenib was done at Bayer HealthCare Pharmaceuticals using a validated liquid chromatographic mass spectrometric method (23). Lower limit of quantification for sorafenib was 0.1 µg/mL. Plasma pharmacokinetic variables, including area under the plasma concentration-time curve (AUC), maximum concentration (Cmax), time to maximum concentration (Tmax), and elimination half-life, were calculated. A noncompartmental method was used to compute pharmacokinetic variables using the KINCALC program developed by Bayer HealthCare. A Wilcoxon signed rank test was used to compare change in pharmacokinetic variables from day –2 to day 15.
Minimum steady-state plasma concentrations (Css,min) for erlotinib and its metabolite OSI-420 were measured on cycle 1 days 15, 16, 22, and 29 using a high-performance liquid chromatography assay (33). Lower limits of quantification were 12.5 ng/mL for erlotinib and 5 ng/mL for OSI-420, respectively.
| Results |
|---|
|
|
|---|
|
2 was reported in all patients prompting a cohort expansion to gain more experience with this toxicity. One of four additional patients enrolled presented with asymptomatic grade 3 hypophosphatemia, resulting in a DLT. The DLT definition was then amended to exclude asymptomatic grade 3 or 4 correctable electrolyte abnormalities. Replacement with oral phosphate was recommended if serum phosphate levels were <0.65 mmol/L; this value was selected arbitrarily as no evidence-based guidelines exist in the literature. Six patients were accrued at dose level 3. One was removed from study due to tumor-related hematuria during the run-in period, thus became inevaluable for DLT and necessitating replacement by another patient. From six patients, one developed grade 2 intolerable diarrhea and anorexia on cycle 1 day 24, hence resulting in a DLT. As only one DLT was encountered at dose level 3, 400 mg twice daily sorafenib with 150 mg daily erlotinib given continuously was declared the RPTD. Dose delays and reductions are shown in Table 2
.
|
|
|
|
|
|
|
| Discussion |
|---|
|
|
|---|
Although all patients at dose level 3 were able to tolerate full doses of both drugs during their first cycle, a cumulative effect was noticed with every patient requiring dose reductions after one to four cycles, mainly due to fatigue, gastrointestinal, and skin toxicity. In contrast, patients treated at dose level 2 seemed to tolerate this drug combination better for extended durations. Furthermore, anticancer activity was observed in one patient at dose level 2 with a long-lasting partial response. Hence, it is reasonable to begin with the RPTD of this combination at 400 mg twice daily sorafenib and 150 mg daily erlotinib while being wary that those who remain on therapy may require dose modifications of one or both drugs in the longer term. It is debatable whether future phase II studies should compare both dosages for safety and efficacy over a longer period to truly evaluate the effect of cumulative toxicity of this combination.
The pharmacokinetic results of sorafenib and erlotinib obtained were similar to those from single-agent trials, where moderate to significant interpatient variability for both drugs has been described (14, 23, 35, 36). Sorafenib exhibited an early absorption phase followed by delayed secondary peaks that could be attributed to enterohepatic circulation of its glucuronide metabolite and the interconversion of the N-oxide metabolite back to the parent compound (Fig. 2). Mean AUC0-12, Cmax, and Cmin values for sorafenib were dose dependent but did not vary significantly in the presence or absence of erlotinib, suggesting a lack of effect of erlotinib on sorafenib pharmacokinetics. This is consistent with the lack of major overlapping toxicity in the clinical setting, enabling the delivery of both drugs at their full single-agent doses. The study design and sampling schedule in this study did not permit drawing definitive conclusions of the potential effect of sorafenib on erlotinib pharmacokinetics.
Treatment outcomes in most advanced epithelial neoplasms remain poor in spite of recent progress in molecular biology and development of novel anticancer agents. The diversity of molecular abnormalities is felt to partly contribute to the resistance to therapy; therefore, developing combinations of anticancer drugs that may exhibit synergistic or complementary activity seems a reasonable approach (37). However, many questions still need to be addressed for the successful combination of targeted agents in clinical trials (38, 39). For instance, there is no consensus on the level of preclinical additivity or synergism required with targeted combinations before proceeding with clinical evaluations. Furthermore, there are challenges in the attribution of antitumor activity and/or toxicity to the individual agents versus the combination effect. The enthusiasm around the development of regimens that contain several promising targeted agents must be balanced by the need to do well-designed clinical trials instead of empirical combinations. Factors such as cumulative toxicity and pharmacodynamic and pharmacokinetic end points should be considered to better evaluate combined therapies and their potential effect in clinical practice.
Previous studies have evaluated combinations of sorafenib or erlotinib with other targeted agents. A phase I trial of sorafenib with bevacizumab in patients with advanced renal cell cancer showed a substantial increase in the expected toxicity, particularly with sorafenib-related adverse events. This exacerbation was more pronounced when sorafenib was administered at 400 mg twice daily. Patients at that dose level presented with a constellation of severe hand-foot syndrome, stomatitis, and anorexia, leading to remarkable weight loss and decline in performance status (38, 40). It would appear that dual inhibition of the VEGF-VEGFR axis can lead to an undesirable toxicity profile. When sorafenib was combined with the EGFR tyrosine kinase inhibitor gefitinib in a phase I study of patients with progressive or refractory non–small cell lung cancer (41), modest activity and a tolerable toxicity profile consisting mostly of fatigue, diarrhea, and liver enzyme elevation were reported. Erlotinib has also been previously tested in combination with other targeted drugs, such as bevacizumab, in patients with non–small cell lung cancer and renal cell cancer (42, 43). The toxicity profile was similar in both studies with rash, diarrhea, and proteinuria as the most relevant adverse events, ranging from mild to moderate in severity. These trials of sorafenib plus gefitinib and erlotinib plus bevacizumab seem to echo our findings in their nonoverlapping toxicity profiles, suggesting that simultaneous inhibition of the EGFR and VEGFR axes seems feasible.
The current study combined for the first time sorafenib and erlotinib, and the toxicity profile and preliminary efficacy evaluations revealed encouraging results. Three of 15 evaluable patients achieved confirmed partial response and 9 patients had stable disease as best response. One patient with metastatic cholangiocarcinoma achieved a long-lasting partial response. Recent studies suggested a relevant implication of the EGFR-mitogen-activated protein kinase pathway and the VEGF-VEGFR system in this tumor pathogenesis (44). A phase II trial with erlotinib in advanced cholangiocarcinoma showed modest activity (45) and one with single-agent sorafenib is ongoing.6 Another confirmed partial response was observed in a patient with heavily pretreated metastatic pancreatic islet cell carcinoma with liver metastases. High expression of EGFR, phosphorylated EGFR, extracellular signal-regulated kinase, and phosphorylated extracellular signal-regulated kinase as well as VEGF-C and its receptors (VEGFR-2/VEGFR-3) has been recently reported in neuroendocrine tumors, suggesting involvement of these molecular mechanisms in tumor growth and metastasis and therefore representing appropriate targets (46, 47). Lastly, a third patient who achieved a confirmed partial response had metastatic small bowel adenocarcinoma. Although no data confirm a relevant role of EGFR, some reports suggest a significant contribution of VEGF and its receptors to tumor growth through angiogenesis promotion in this tumor type (48).
In this phase I trial, patients with 14 different tumor types were enrolled with responses being observed in malignancies outside of the known spectrum where sorafenib and erlotinib have shown single-agent activity. This finding is encouraging and may launch evaluation opportunities in these and other tumor sites.
| Footnotes |
|---|
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 accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Note: This study was presented in part in the 18th European Organization for Research and Treatment of Cancer-National Cancer Institute-AACR Symposium on Molecular Targets and Cancer Therapeutics, November 2006, Prague, Czech Republic.
5 http://www.fda.gov/bbs/topics/NEWS/2005/NEW01282.html ![]()
6 http://www.clinicaltrials.gov/ct/show/NCT00238212 ![]()
Received 2/15/07; revised 4/27/07; accepted 5/22/07.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
A. Broniscer, S. J. Baker, C. F. Stewart, T. E. Merchant, F. H. Laningham, P. Schaiquevich, M. Kocak, E. B. Morris, R. Endersby, D. W. Ellison, et al. Phase I and Pharmacokinetic Studies of Erlotinib Administered Concurrently with Radiotherapy for Children, Adolescents, and Young Adults with High-Grade Glioma Clin. Cancer Res., January 15, 2009; 15(2): 701 - 707. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |