First Published Online October 6, 2008 The Oncologist, Vol. 13, No. 10, 1084-1096, October 2008; doi:10.1634/theoncologist.2008-0120 © 2008 AlphaMed Press
Targeted Therapies for Metastatic Renal Cell Carcinoma: An Overview of Toxicity and Dosing StrategiesaBaylor University Medical Center, Sammons Cancer Center, Dallas, Texas, USA; bCity of Hope National Medical Center, Duarte, California, USA; cUniversity of Texas Health Science Center, San Antonio, Texas, USA; dMemorial Sloan-Kettering Cancer Center, New York, New York, USA Key Words. Renal cell carcinoma • Temsirolimus • Sunitinib • Sorafenib • Safety • Dosing Correspondence: Thomas E. Hutson, D.O., Pharm.D., Baylor University Medical Center, GU Oncology Program, Texas Oncology, PA, Sammons Cancer Center, 3535 Worth Street, Dallas, Texas 75246, USA. Telephone: 214-370-1069; Fax: 214-370-1190; e-mail: thomas.hutson{at}usoncology.com Received May 21, 2008; accepted for publication September 3, 2008; first published online in THE ONCOLOGIST Express on October 6, 2008.
Disclosure: Employment/leadership position: None; Intellectual property rights/inventor/patent holder: None; Consultant/advisory role: Thomas E. Hutson, Pfizer, Bayer, GlaxoSmithKline, Wyeth; Robert A. Figlin, Wyeth, Novartis, Pfizer, Kely, Aveo Pharmaceuticals, Innate Pharmaceuticals; Honoraria: Thomas E. Hutson, Pfizer, Bayer, Wyeth; Research funding/contracted research: Thomas E. Hutson, Pfizer, Bayer, Wyeth, GlaxoSmithKline, Genentech; Robert A. Figlin, Wyeth, Novartis, Keryx, Amgen, Pfizer, Argos Pharmaceuticals; Robert J. Motzer, Pfizer, Wyeth, Genentech; Ownership interest: None; Expert testimony: None; Fees for non-CME services: Robert J. Motzer, Bayer/Onyx.
This article is available for continuing medical education credit at CME.TheOncologist.com
The targeted therapies sunitinib, sorafenib, temsirolimus, and bevacizumab (when used in combination with interferon- 2a) have dramatically improved outcomes for patients with advanced renal cell carcinoma (RCC). Clinical application of these novel agents outside the trial setting, however, may present some challenges for treating individual patients with unique needs. In some patients, dose modifications may be considered for potential drug interactions and for management of severe cases of hematologic or nonhematologic toxicities. The more common grade 3 or 4 side effects with sunitinib and sorafenib include hypertension, fatigue, hand–foot syndrome, elevated lipase, lymphopenia, and neutropenia. Congestive heart failure is a less common but serious side effect that warrants treatment discontinuation. Temsirolimus exhibits a different side-effect profile, with the more common grade 3 or 4 side effects being metabolic in nature (i.e., elevated triglycerides, elevated glucose, hypophosphatemia) as a result of its inhibitory effects on the mammalian target of rapamycin–regulated lipid and glucose pathways. Asthenia, rash, and dyspnea also occur in patients receiving temsirolimus. Virtually all of the side effects associated with these agents can be managed effectively in the majority of patients with medical treatment or supportive interventions. Recognition and prompt management of side effects are important to avoid unnecessary dose reductions that may result in suboptimal efficacy.
Whereas chemotherapy dosing is based on the maximum-tolerated dose (MTD) of a drug, dosing of targeted cancer therapies is not necessarily the MTD but, rather, is based on the inhibition of biologic targets in the tumor and surrogate tissues as well as safety assessments. Investigational dosing regimens are then fine-tuned during phase II and III testing to recommend a clinical dose that maximizes tolerability while providing optimal biologic activity and clinical efficacy [1]. This paper describes the clinical rationale for the recommended dosing and reviews the safety data at clinical doses for each of the novel targeted therapies approved for treatment of renal cell carcinoma (RCC): sunitinib, sorafenib, and temsirolimus. Because no randomized controlled clinical trials directly compare the relative safety and tolerability of these targeted agents, we compare the available published data from pivotal trials (Tables 1 and 2 ). Guidelines for dose modifications and for adjustment/interruption for management of toxicities are summarized for each therapy (Table 3).
Sunitinib Sunitinib is a small molecule inhibitor of certain receptor tyrosine kinases, including vascular endothelial growth factor receptor (VEGFR) types 1 and 2 (FLT-1 and FLK-1/KDR), platelet-derived growth factor receptors (PDGFR- , PDGFR-β), stem cell factor receptor (c-KIT), and the FLT-3 and RET kinases [2]. Clear cell RCC is characterized by frequent loss of the von Hippel-Lindau tumor suppressor gene, resulting in increased transcription of several proteins, including VEGF and PDGF [3]. Tumor angiogenesis is stimulated in part by VEGF binding to its receptor. Signaling through this receptor can be blocked in preclinical models by treatment with sunitinib. Preclinical data suggest that sunitinib has antitumor activity that might result predominantly from inhibition of tumor angiogenesis, although sunitinib also has direct antiproliferative and apoptotic effects on certain tumor types [4]. Sunitinib doses selected for phase I clinical testing were based on biologic activity in preclinical models (i.e., the dose needed to achieve the plasma concentration necessary to inhibit the VEGF receptor) rather than on MTD, which is reflected in animal models as weight loss [2]. Early sunitinib phase I studies included single-dose studies of the oral drug in healthy adults to assess toxicity and pharmacokinetic parameters, and several multidose studies in patients with acute myelogenous leukemia or a variety of advanced solid tumors [2]. Because of the prolonged half-life of sunitinib and its main metabolite and evidence of accumulation with continuous daily dosing, alternate dosing schedules were explored. Schedules evaluated in cancer patients included daily and every-other-day administration and incorporated planned rest periods (i.e., 3-week cycle of 2-week treatment, then 1-week rest period [schedule 2/1]; 4-week cycle of 2-week treatment, then 2-week rest period [schedule 2/2]; or 6-week cycle of 4-week treatment, then 2-week rest period [schedule 4/2]). Confirmed partial responses were observed at the 50-mg and 75-mg dose levels on schedules 4/2 or 2/2. Fatigue was the most common adverse event (AE) reported in phase I studies, regardless of tumor type. Based on the results of these studies, the recommended dose for phase II trials was 50 mg orally once daily using schedule 4/2 [5]. Two single-arm phase II trials of oral sunitinib on this schedule displayed high partial response rates (34%–40%) and a median time to tumor progression of 8.3 months in patients with cytokine-refractory advanced RCC. Toxicities were similar to those in phase I studies, with fatigue being the most common grade 3 AE (11%) [6, 7].
The phase III trial of oral sunitinib (50 mg, 4/2 schedule) versus interferon (IFN)-
Treatment and Dose Adjustments Pharmacokinetic analyses indicate no clinically relevant effects of age, body weight, creatinine clearance, race, gender, or Eastern Cooperative Oncology Group performance status score on pharmacokinetic profiles, suggesting that dose adjustment is not required based on these factors. However, studies excluded patients with serum creatinine levels >2.0x the upper limit of normal (ULN), so caution should be used in patients with severely impaired renal function. Additionally, no dose adjustment is required when administering sunitinib to patients with Child-Pugh Class A or B hepatic impairment, but sunitinib has not been studied in patients with severe (Child-Pugh Class C) hepatic impairment. Studies in cancer patients excluded patients with alanine aminotransferase or aspartate aminotransferase levels >2.5x the ULN or, if as a result of liver metastases, >5.0x the ULN [11]. Sunitinib is metabolized primarily by cytochrome P450 (CYP)3A4 to produce its primary active metabolite, which is further metabolized by CYP3A4 [12]. Therefore, strong CYP3A4 inhibitors may increase sunitinib plasma concentrations so that the selection of an alternate concomitant medication with no or minimal CYP3A4 inhibition potential is recommended. A dose reduction of sunitinib to a minimum of 37.5 mg daily should be considered if a strong CYP3A4 inhibitor must be used (Table 3). Additionally, CYP3A4 inducers may decrease sunitinib plasma concentrations and should be avoided. A sunitinib dose increase to a maximum of 87.5 mg daily should be considered if coadministration with a CYP3A4 inducer is necessary; however, patients should be monitored carefully for toxicities. In human liver microsomes and hepatocytes, studies indicated that sunitinib does not induce or inhibit the major CYP enzymes [11].
Medical Management of Selected Toxicities Hypertension. Patients receiving sunitinib should be monitored for hypertension and, if needed, treated with standard antihypertensive therapy, including angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, calcium channel blockers, beta-blockers, and diuretics [12]. Nondihydropyridine calcium channel blockers, such as verapamil and diltiazem, should be avoided because of their known inhibition of CYP3A4. Other antihypertensive drugs may also potentially interact with CYP enzymes and could interact with sunitinib. Patients with preexisting hypertension may, therefore, require adjustment of antihypertensive medications during sunitinib therapy. The objective of treatment is to normalize blood pressure (resting rate, <140/90 mmHg). In cases of severe hypertension (>200 mmHg systolic or >110 mmHg diastolic) [13], sunitinib should be temporarily suspended until the hypertension is adequately controlled. With appropriate medical management of hypertension, sunitinib dose reductions are rarely necessary.
Reversible Posterior Leukoencephalopathy Syndrome. Temporary suspension of sunitinib is recommended in rare cases (<1%) of patients with seizures and radiologic evidence of reversible posterior leukoencephalopathy syndrome (RPLS). Signs and symptoms consistent with RPLS, such as hypertension, headache, decreased alertness, altered mental functioning, and visual loss, including cortical blindness, should be controlled with medical management. Following resolution, sunitinib may be resumed [14].
Cardiac Toxicity. Emerging safety data indicate that cardiotoxicity may be associated with sunitinib at a higher rate than that seen in clinical trials. At one institution, 12.5% of patients receiving sunitinib for either RCC or gastrointestinal stromal tumor developed symptomatic grade 3 or 4 heart failure 22–435 days after the initiation of treatment [15]. Left ventricular dysfunction is the main cardiac side effect of sunitinib and might be partly a result of cardiomyocyte toxicity exacerbated by hypertension [16]. Therefore, blood pressure and the left ventricular ejection fraction should be closely monitored in those patients receiving sunitinib who have a history of coronary artery disease or cardiac risk factors [16]. For patients without cardiac risk factors, a baseline evaluation of the ejection fraction should be considered. Sunitinib prolongs the QT interval in a dose-dependent manner, which may lead to an increased risk for ventricular arrhythmias, including torsades de pointes (<1% of sunitinib-exposed patients). Caution should, therefore, be used in patients with a history of QT prolongation and in those taking antiarrhythmics, or patients with preexisting cardiac disease, bradycardia, or electrolyte disturbances (Mg2+, K+) [11].
Hypothyroidism. Hypothyroidism has been reported in patients as early as 1–2 weeks after the initiation of sunitinib treatment, and the incidence increases progressively with duration of therapy [10]. In patients with RCC treated with sunitinib, 85% had abnormal results on one or more thyroid function tests, including elevation of thyroid-stimulating hormone (TSH) levels, decreased T3 levels, and, less commonly, decreased T4 or free-thyroxine index levels [10]. An abnormal serum TSH concentration and mild symptoms consistent with hypothyroidism, such as fatigue, anorexia, edema, fluid retention, or cold intolerance, may precede the onset of overt hypothyroidism, which may rapidly progress from mild to profound [13]. Regular surveillance of thyroid function is warranted in patients receiving sunitinib. TSH measurements should be taken at baseline and every 2–3 months during treatment; any abnormal TSH value or symptoms suggestive of hypothyroidism should prompt a more thorough evaluation. Patients with subclinical hypothyroidism should also be considered for treatment; typical doses of levothyroxine should normalize TSH levels and resolve symptoms. Patients with cancer, including those with RCC, who are treated with sorafenib have a significant risk of developing hypertension (relative risk, 6.1; 95% confidence interval [CI], 2.4–15.3; p < .001, compared with control treatments) [17]. Therefore, appropriate monitoring and treatment are strongly recommended to prevent cardiovascular complications. Hypertension associated with sorafenib has been easily managed with antihypertensive therapy (agents acting on the renin–angiotensin system, beta-blocking agents, and calcium channel blockers) and rarely has led to treatment discontinuation (<1%) [18, 19]. Prescribing guidelines suggest that patients be monitored weekly for hypertension during the first 6 weeks of treatment and regularly thereafter [20]. In cases of severe or persistent hypertension, temporary or permanent discontinuation of sorafenib should be considered, despite initiation of antihypertensive therapy. Thyroid hormone replacement benefits about 50% of patients who develop overt hypothyroidism [10].
Skin Toxicity. Skin changes associated with sunitinib include hand–foot syndrome, changes in hair color, skin rash, dry skin, skin discoloration, acral erythema, and subungual splinter hemorrhages. Skin toxicity typically occurs after 3–4 weeks of treatment. Hand–foot syndrome presents as painful symmetric erythematous and edematous areas on the palms and soles, often accompanied by paresthesia, tingling, or numbness, and desquamation can occur in severe cases. Palliative intervention includes moisturizers, foot and hand care products (e.g., gel pad inserts, cotton gloves, and clobetasol propionate cream), and medication for pain management [13]. Generalized skin rashes (erythema, maculopapular or seborrheic dermatitis) are mainly grades 1 or 2, tend to decrease over time, and rarely require dose reduction. Moisturizing skin lotions or creams may be helpful if the skin is very dry.
Sorafenib A pooled analysis of four phase I trials confirmed that oral sorafenib was safe and was associated with clinically meaningful disease stabilization in patients with advanced cancers [23]. Continuous administration of oral sorafenib at a dose of 400 mg twice daily was found to be the MTD and was recommended for further investigation [24]. This dose was subsequently shown in a phase II randomized discontinuation trial to be well tolerated by patients with metastatic RCC (n = 202) [25]. The PFS interval was longer with sorafenib than with placebo upon randomization of patients with stable disease after 12 weeks of therapy (p = .0087; sorafenib median, 24 weeks versus placebo median, 6 weeks) [25]. The pivotal, randomized, placebo-controlled phase III Treatment Approaches in Renal cancer Global Evaluation Trial (TARGET) (n = 903) further evaluated sorafenib at a dose of 400 mg twice daily versus placebo in patients with cytokine-refractory RCC (Table 1) [18]. The PFS duration was significantly longer for the sorafenib group than for the placebo group (HR, 0.44; p < .01). The median PFS time was twofold longer for the sorafenib group than for the placebo group (5.5 months versus 2.8 months). The final overall survival data did not demonstrate a significantly lower risk for death with sorafenib (HR, 0.88; p = .146), but when patients who crossed over to sorafenib were censored, the survival analysis showed a significant difference (HR, 0.78; p = .029) [26].
In a phase II trial of first-line treatment with sorafenib (400 mg twice daily) versus IFN- The TARGET study, which was placebo controlled [18], provided an ideal opportunity to discriminate between drug-related toxicities and AEs associated with the RCC disease process. Most AEs were grade 1 or 2 in severity, graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0 (NCI CTCAE v 3.0) [30], and occurred within the first two cycles of sorafenib treatment [31]. Common AEs in the sorafenib group, but not the placebo group, were diarrhea, rash, fatigue, hand–foot syndrome, alopecia, and nausea. Bleeding (predominantly grade 1) was also more frequent with sorafenib (15%) than with placebo (8%), but the incidence of serious hemorrhage was similar in the two groups [18]. Grade 3 or 4 AEs occurred with similar frequency in patients receiving placebo (Table 2) [18]. For example, grade 3 or 4 anemia occurred in 3% of patients receiving sorafenib and in 4% of patients receiving placebo. Febrile neutropenia or grade 4 thrombocytopenia did not occur with sorafenib. Hypertension was the most frequent sorafenib-related AE and occurred in 1% of patients receiving sorafenib and in no patients on placebo. It was generally observed during the first treatment cycle. Hypertension was also the most frequent AE that led to hospitalization or death. Ischemia or infarction also were more frequent in patients receiving sorafenib, but the absolute numbers of events were low (12 patients [3%] versus two patients [1%], respectively); most of these patients had other cardiac risk factors [18]. Dose interruptions were most frequently a result of dermatologic reactions (hand–foot syndrome or rash) and gastrointestinal AEs, including diarrhea [18].
Treatment and Dose Adjustments Sorafenib is metabolized primarily in the liver by the CYP system, particularly CYP3A4, as well as glucuronidation mediated by UGT1A9 [20]. Coadministration of strong CYP3A4 inducers decreased sorafenib plasma concentrations an average of 37% (Table 3) and should be avoided. A dose increase may be considered if a concomitant strong CYP3A4 inducer is needed, but the patient should be monitored for toxicity. A specific dose increase has not been established. Based on drug-interaction studies in healthy volunteers, sorafenib metabolism is not altered by strong CYP3A4 inhibitors, so dose adjustment should not be necessary if coadministered with these agents. Sorafenib is also a competitive inhibitor of the CYP2B6 and CYP2C8 isozymes. Therefore systemic exposure to agents that are substrates of CYP2B6 and CYP2C8 should be expected to increase when coadministered with sorafenib. The effect of sorafenib on warfarin, assessed indirectly by measuring the prothrombin time–international normalized ratio in patients treated with sorafenib versus placebo, suggested that sorafenib did not inhibit warfarin metabolism [20]. Increased systemic exposure to various other antineoplastic drugs may occur if coadministered with sorafenib; therefore, caution is recommended [20]. These compounds include docetaxel, doxorubicin, and fluorouracil or compounds that are conjugated by UGT1A1 (e.g., irinotecan) (Table 3). Sorafenib had no significant effect on the pharmacokinetics of gemcitabine, oxaliplatin, or paclitaxel/carboplatin when tested with commonly used dosing regimens [20]. Although hepatic impairment may reduce the plasma concentration of sorafenib, the optimal dose in RCC patients with hepatic impairment is not established. No dosage adjustment is necessary when administering sorafenib to patients with mild, moderate, or severe renal impairment who are not undergoing dialysis; sorafenib has not been studied in patients undergoing dialysis [20].
Medical Management of Selected Toxicities Hypertension. Patients with cancer, including those with RCC, who are treated with sorafenib have a significant risk of developing hypertension (relative risk, 6.1; 95% CI, 2.4–15.3; p < .001, compared with control treatments) [17]. Therefore, blood pressure monitoring and treatment, if needed, with antihypertensive therapy (agents acting on the renin–angiotensin system, beta-blocking agents, and calcium channel blockers) are recommended to prevent cardiovascular complications [20]. Patients should be monitored weekly for hypertension during the first 6 weeks of treatment and regularly thereafter [20]. Hypertension associated with sorafenib has been easily managed with antihypertensive therapy, and rarely leads to treatment discontinuation (<1%) [18, 19].
Skin Toxicity. Prescribing guidelines for the management of sorafenib-associated skin toxicities include topical therapies, temporary interruption and/or dose modification, or permanent discontinuation in severe or persistent cases [20]. Dermatologic symptoms usually occur within 6 weeks of sorafenib therapy and management varies according to presentation [20, 31]. Skin toxicities associated with sorafenib are generally reversible and resolved using topical therapies, temporary treatment interruption, or dose modification. Sorafenib is associated with a significant risk of developing hand–foot syndrome (relative risk, 6.6; 95% CI, 3.7–11.7; p < .001, compared with control treatments) [33]. Early signs are tingling and numbness, with slight redness or a mild hyperkeratosis [31]. Clinical manifestations include painful, symmetrical, red, and swollen areas on the palms and soles; the lateral sides of the fingers or the periungual zones can also be affected [34]. If hand–foot syndrome progresses to grade 3, it is recommended that treatment be interrupted for 1–2 weeks combined with symptomatic treatment until symptoms return to grade 0–1 [20]. When treatment is resumed, the sorafenib dose should be decreased by one dose level. Patients may attempt the same dose with proper supportive care if toxicity has resolved. Upon the third occurrence of grade 3 symptoms, sorafenib should be discontinued [20].
Temsirolimus Initial clinical studies in cancer patients investigated i.v. temsirolimus administered at dosages that were corrected for body surface area (mg/m2) and were designed to establish tolerability, safety, and pharmacokinetic parameters [42, 43]. When administered as a 30-minute infusion once weekly, temsirolimus was well tolerated over a wide range of doses (7.5–165 mg/m2) [42]. Rash and mucositis/stomatitis were the most frequent drug-related AEs, and thrombocytopenia was the main dose-limiting toxicity [42]. Antitumor activity was observed in heavily pretreated patients, including patients with advanced RCC, who received different doses and schedules [42, 43]. Temsirolimus is not a prodrug, although its main metabolite, sirolimus, also has mTOR inhibitory activity [14]. Exposure is considered to be a composite of temsirolimus plus sirolimus levels in whole blood. Pharmacokinetic analysis of i.v. temsirolimus dosages corrected for body surface area indicated that dose normalization did not improve variability in exposures over those of a flat dose [44]. Therefore, once-weekly flat dosing was subsequently used for phase II and III studies in patients with advanced RCC.
In the phase II RCC study, advanced RCC patients who had previously received, or were not candidates for, cytokine therapy were treated with 25 mg, 75 mg, or 250 mg i.v. temsirolimus as a once-weekly 30-minute infusion [44]. Although the objective response rate (complete response plus partial response) for the total population was only 7% (95% CI, 3.2%–13.7%), 51% of patients experienced clinical benefit defined as complete response, partial response, minor response, or stable disease lasting Toxicity was similar across the three dose levels studied, but dose reductions and discontinuations were more frequent at the higher doses. Overall, the most frequent grade 3 or 4 temsirolimus-related AEs (n = 110) were hyperglycemia (17%), hypophosphatemia (13%), anemia (9%), and hypertriglyceridemia (6%) [44]. Six patients had possible nonspecific pneumonitis; five received temsirolimus at a dose of 75 mg and one received temsirolimus at a dose of 25 mg, suggesting a possible dose relationship [44]. Whole blood concentrations of temsirolimus following the lowest dose studied, 25 mg, are comparable with or higher than the temsirolimus concentrations needed for antitumor activity in tumor cells and in tumor xenografts [42, 44]. Thus, the 25-mg dose, which had optimal clinical efficacy and tolerability, was selected as the monotherapy dose for the phase III trial in patients with advanced RCC and poor prognostic features [44, 45].
The randomized phase III Global Trial for Advanced Renal Cell Carcinoma (Global ARCC Trial) compared temsirolimus, IFN-
Temsirolimus as a single agent resulted in longer overall survival (HR for death, 0.73; 95% CI, 0.58–0.92; p = .008) and PFS (p < .001) times than with IFN-
Fewer patients experienced serious AEs in the temsirolimus group than in the IFN-
Treatment and Dose Adjustments
Temsirolimus treatment may be interrupted or adjusted because of AEs (Table 3). Temsirolimus should be held for an absolute neutrophil count <1,000/µl, platelet count <75,000/µl, or NCI CTCAE v 3.0 grade Patient characteristics such as age, gender, and race did not affect the pharmacokinetics and disposition of temsirolimus, and dosing should not be adjusted based on these factors [14, 48]. The influence of hepatic dysfunction and/or hepatic metastases on temsirolimus disposition has not yet been fully determined, but clearance of oral sirolimus is known to be 33% lower in patients with hepatic impairment or with the concomitant use of drugs that inhibit CYP3A4 [49, 50]. Temsirolimus and sirolimus are both substrates of CYP3A4; therefore, coadministration of strong CYP3A4 inhibitors or inducers should be avoided [14]. Agents that are strong CYP3A4 inhibitors (e.g., ketoconazole) may increase exposure to the metabolite sirolimus and should be avoided. A dose reduction to 12.5 mg should be considered if a strong CYP3A4 inhibitor must be coadministered (Table 3). This dose is predicted to adjust the area under the concentration–time curve to the range observed without inhibitors. If the strong inhibitor is discontinued, a washout period of about 1 week should be allowed before the dose is adjusted back to the dose used before the strong CYP3A4 inhibitor was initiated. In contrast, strong CYP3A4 inducers (e.g., phenytoin) may decrease exposure to the metabolite sirolimus, but temsirolimus exposure is not affected [14, 51]. If an alternative to the CYP3A4 inducer cannot be administered, pharmacokinetic studies indicate that increasing the temsirolimus dose from 25 mg to 50 mg should be considered (Table 3) [14]. Upon discontinuation of the strong CYP3A4 inducer, the temsirolimus dose should be returned to 25 mg or the dose used before the strong CYP3A4 inducer was initiated. Based on in vitro drug interaction data, clinically significant effects are not anticipated when temsirolimus at a dose of 25 mg is given with agents metabolized by CYP2D6 or CYP3A4 [14].
Medical Management of Selected Toxicities Hyperglycemia. Close monitoring of fasting blood sugar and hemoglobin A1c and early intervention of hyperglycemia are recommended for optimal patient management [52]. Hyperglycemia may be manifested as excessive thirst or increased urination volume or frequency, and may require diet modification and initiation, or a dose increase of insulin and/or oral agents for glycemic control such as sulfonylureas [14, 52].
Hyperlipidemia. Serum cholesterol and triglyceride levels should be tested at baseline and monitored during treatment [14, 52]. Hypertriglyceridemia and hypercholesterolemia are generally manageable with diet modification and initiation of lipid-lowering agents, based on the lipid profile.
Skin Toxicity and Stomatitis. Skin rashes associated with temsirolimus are mostly low grade, maculopapular in nature, and manageable with supportive measures such as fragrance-free moisturizers and possibly topical corticosteroids [52]. Hand–foot syndrome is not associated with temsirolimus treatment [14]. Stomatitis in patients receiving temsirolimus is typically mild, and supportive management includes oral hygiene, pain control, and hydration (i.v. fluid replacement) if severe [52].
Pneumonitis/Interstitial Lung Disease. Although infrequent, surveillance for pneumonitis/interstitial lung disease is warranted because of rare fatal cases reported in phase I and II trials. In the phase III trial, four (2%) of 208 patients treated with temsirolimus developed interstitial lung disease of varying severities (one patient grade 3 or 4) during study weeks 9–41 [52]. Monitoring may include chest x-ray, computed tomography scan, or pulmonary function tests (decreased diffusing capacity of the lung to carbon monoxide measurement on pulmonary function tests) [52]. Symptoms indicative of pneumonitis include pleural effusion, hypoxia, cough, dyspnea, and malaise in the absence of a nondrug cause. Management guidelines are not yet established for patients who develop radiographic changes, with or without clinical respiratory symptoms indicative of interstitial lung disease, while on temsirolimus therapy. In the clinical trial experience, patients treated with temsirolimus who displayed radiologic changes but no symptoms continued temsirolimus treatment without dose reduction or interruption. Temsirolimus was temporarily interrupted in patients with radiologic changes and a few symptoms consistent with interstitial lung disease until these symptoms resolved. For patients with increasing clinical symptoms in conjunction with decreased pulmonary function, temsirolimus was discontinued and patients were treated with high-dose prednisone [52].
Bevacizumab
Based on the results of a randomized phase III trial, bevacizumab in combination with IFN- Bevacizumab is approved in the U.S. for use in combination with 5-fluorouracil–based chemotherapy for the treatment of metastatic colorectal cancer, in combination with carboplatin and paclitaxel for the treatment of non-small cell lung cancer, and in combination with paclitaxel for the treatment of metastatic human epidermal growth factor receptor 2–negative breast cancer [56]. Thus, the safety profile of bevacizumab has been characterized when administered in combination with a range of chemotherapeutic agents. Bevacizumab has resulted in gastrointestinal perforation (sometimes fatal) and wound-healing complications. Other serious side effects in patients receiving bevacizumab with chemotherapy included nongastrointestinal fistula formation, strokes or blood clots, and hypertension [56]. There are no dose-reduction recommendations for the use of bevacizumab; if needed, bevacizumab should be either discontinued or temporarily suspended.
In the AVOREN trial, the most common grade
Everolimus Hyperglycemia, hypercholesterolemia, hyperlipidemia, stomatitis, rash, and diarrhea were more common in the everolimus group than in the placebo group [58]. Pneumonitis was detected in 22 (8%) of 269 patients treated with everolimus, of whom eight had grade 3 severity pneumonitis. A direct comparison of toxicities associated with the two mTOR inhibitors, temsirolimus and everolimus, is complicated by a lack of head-to-head studies and the different study populations in the phase III trials. Given these caveats, the toxicities associated with everolimus appear, in general, to be similar in type and severity to those occurring in patients treated with temsirolimus [45, 52, 58]. A possible exception is the higher percentage of patients with pneumonitis reported in the everolimus trial, but the clinical relevance of this difference is not known.
The toxicities associated with the targeted therapies sunitinib, sorafenib, and temsirolimus for the treatment of patients with RCC are well tolerated, given the benefits they provide. Treatment-related adverse reactions are mainly mild to moderate and are readily managed, in most cases, with medical treatment or supportive measures. Most cases of severe treatment-related adverse reactions are reversible and resolve after dose reduction or treatment interruption. Optimal treatment with these targeted agents requires proactive monitoring, early intervention, and appropriate management of side effects in order to avoid unnecessary dose reductions, interruptions, or even early treatment discontinuation.
Conception/Design: Thomas E. Hutson, Robert A. Figlin, John G. Kuhn, Robert J. Motzer Administrative support: Thomas E. Hutson, Robert A. Figlin, John G. Kuhn, Robert J. Motzer Collection/assembly of data: Thomas E. Hutson, Robert A. Figlin, John G. Kuhn, Robert J. Motzer Data analysis: Thomas E. Hutson, Robert A. Figlin, John G. Kuhn, Robert J. Motzer Manuscript writing: Thomas E. Hutson, Robert A. Figlin, John G. Kuhn, Robert J. Motzer Final approval of manuscript: Thomas E. Hutson, Robert A. Figlin, John G. Kuhn, Robert J. Motzer The authors take full responsibility for the content of the paper but thank Christine H. Blood, Ph.D., from Peloton Advantage, supported by Wyeth, for her assistance in preparing the initial draft of the manuscript and collating the comments of the authors.
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