A guide to clinically relevant drug interactions in oncology

Cancer Drug Dosing in Chronic Kidney Disease and Dialysis

Patients with malignancies have a high prevalence of kidney disease and are often treated with antineoplastic agents that undergo kidney metabolism or excretion or clearance via renal replacement therapies. Thus, the dosing of these agents, including classic chemotherapeutic drugs, targeted therapies, and immunotherapy, must take into account patients' kidney function. In this review, we will discuss the pitfalls of accurate measurement of kidney function and how kidney disease affects both pharmacodynamic and pharmacokinetic properties of drugs. Lastly, we will discuss specific agents and summarize current dosing strategies for use in patients with chronic kidney disease and end-stage kidney disease.

Bradyarrhythmias in Cardio-Oncology

The relationship between bradyarrhythmias and cancer therapies has not been well described but is increasingly recognized. There have been extensive advances in oncological pharmacotherapy, with several new classes of drugs available including targeted agents, immune checkpoint inhibitors and CAR T cell therapy. This increasing repertoire of available drugs has revolutionized overall prognosis and survival of cancer patients but the true extent of their cardiovascular toxicity is only beginning to be understood. Previous studies and published reviews have traditionally focused on conventional chemotherapies and in arrhythmias in general, particularly tachyarrhythmias. The number of patients with both cancer and cardiovascular problems is increasing globally and oncologists and cardiologists need to be adept at managing arrythmia based scenarios. Greater collaboration between the two specialties including studies with prospective data collection in Cardio-Oncology are much needed to fill in knowledge gaps in this arena. This case-based review summarizes current available evidence of cancer treatment-related bradyarrhythmia incidence (including its different subtypes), possible mechanisms and outcomes. Furthermore, we propose a stepwise surveillance and management protocol for patients with suspected bradyarrhythmia related to cancer treatment.

Renal function impairment in cervical cancer patients treated with cisplatin-based chemoradiation: A review of medical records in a Zimbabwean outpatient department

Background

There is a potential increase in risk of renal function impairment among patients with invasive cervical cancer (ICC) who are HIV-positive and treated with cisplatin-based concurrent chemoradiation (CCRT). This concern is due to overlapping nephrotoxicity of the drugs, and nephropathy from the diseases themselves. There is limited literature available for the short-term renal outcomes for HIV-positive patients with ICC during routine clinical management. This study aimed to assess if HIV-infection increased the risk of renal impairment in ICC patients treated with CCRT, and explore the respective risk factors.

Materials and methods

This was a retrospective review of records of ICC patients treated with at least one cycle of weekly cisplatin during CCRT at the Parirenyatwa Radiotherapy Center from January 2017-December 2018. The RIFLE criteria were used to classify renal impairment. Analyses were performed with Fisher’s Exact tests, Wilcoxon rank sum tests. Odds ratios (OR) were generated using logistic regression. All statistical tests were 2-sided at a 5% level of significance.

Results

Seventy-two eligible patients were identified, 32 (44.44%) were HIV-positive. HIV-positive patients were younger (p = 0.002), had lower albumin levels (p = 0.014) and received lower cisplatin doses (p = 0.044). The mean percent reduction in estimated glomerular filtration rate (eGFR) from baseline was -19% (95% CI: -25.9% to -13.2%) for all patients. Thirty-one (43.1%) patients experienced renal impairment, 50% and 37.5% of HIV-positive and -negative patients respectively (p = 0.287). HIV-infection was associated with an adjusted OR of 1.16 (95% CI 0.35–3.43, p = 0.769). Baseline eGFR< 60ml/min was the only independent predictor of renal impairment, OR 0.25 (95% CI: 0.07–0.85). Baseline eGFR<60ml/min was also associated with receipt of lower cisplatin doses (p = 0.044).

Conclusion

HIV-infection was not associated with elevated risk of renal impairment. Patients with an eGFR<60ml/min appear to be managed more cautiously reducing their risk for renal impairment during cisplatin therapy. The high prevalence of renal impairment in this population suggests the need for optimization of pre-treatment protocols.

Concomitant Drug Treatment and Elimination in the RCC-affected Kidneys: Can We Kill Two Birds with One Stone?

BACKGROUND

The kidneys are vital organs acting as the body's filters that eliminate drugs and other waste products from the body. For effective cancer therapy, a delicate balance is required in the drug treatment and its elimination, which is critical for drug accumulation, toxicity, and kidney malfunction. However, how renal cell carcinoma (RCC) affects the kidneys in safely eliminating the byproducts of drug treatments in patients with severely dysregulated kidney functions had remained elusive. Recent advancements in dose adjustment have added to our understanding regarding how drug treatments could be effectively regulated in aberrant kidney cells, driving safe elimination and reducing drug accumulation and toxicity at the right time and space. Dose adjustment is the only standard systemic way applicable; however, it presents certain limitations. There is significant room for developing new strategies and alternatives to improve it.

OBJECTIVES

Our analysis of the available treatments in literature discusses the treatment and their safe eliminations. In this study, we give an overview of the measures that could be taken to maintain the elimination gradient of anti-cancer drugs and restore normal kidney function in RCC. Differential therapeutics of RCC/mRCC in various clinical phase trials and the interaction of targeted therapeutics in response to vascular endothelial growth factor (VEGF) were also discussed.

CONCLUSION

Such information might suggest a new direction in controlling treatment with safe elimination through dose adjustment and its associated alternatives in a judicious manner. A strategy to systematically focus on the safe elimination of anti-cancer drugs in RCC strongly needs advocating.

Clinical outcomes of adults with hemophagocytic lymphohistiocytosis treated with the HLH-04 protocol: a retrospective analysis

Hemophagocytic lymphohistiocytosis (HLH) is a rare syndrome of pathologic immune activation in children that is increasingly being recognized in adults. Efficacy data for the HLH-04 protocol in adults is lacking. This study retrospectively analyzed 31 adult patients, median age 46 years, who received HLH-04 from 1/1/2004 to 5/1/2018. HLH etiology included malignancy (n = 9), autoimmune (n = 8), infection (n = 8), and idiopathic (n = 6). Eighteen patients were evaluable for response at week 4 with 7 having no response, 11 reaching partial response, and 0 reaching complete response (CR). Six patients eventually achieved CR at a median 195 days. The 1-year overall survival (OS) was 35% and median OS was 3.2 months. Univariate analysis showed shorter survival for hemoglobin <9 g/dL (HR 4.29, p = 0.003), platelets <100 × 10⁹/L (HR 4.06, p = 0.027), ANC <1 × 10⁹/L (HR 5.24, p = 0.001), and total bilirubin >1.2 mg/dL (HR 3.30, p = 0.022). Outcomes of adults treated with HLH-04 remain dismal and newer treatment modalities are needed.

Prediction of seriniquinone-drug interactions by in vitro inhibition of human cytochrome P450 enzymes

Seriniquinone is a secondary metabolite isolated from a rare marine bacterium of the genus Serinicoccus. This natural quinone is highlighted for its selective cytotoxic activity toward melanoma cancer cells, in which rapid metastatic properties are still a challenge for clinical treatment of malignant melanoma. The progress of seriniquinone as a promising bioactive molecule for drug development requires the assessment of its clinical interaction potential with other drugs. This study aimed to investigate the in vitro inhibitory effects of seriniquinone on the main human CYP450 isoforms involved in drug metabolism. The results showed strong inhibition of CYP1A2, CYP2E1 and CYP3A, with IC₅₀ values up to 1.4 μM, and moderate inhibition of CYP2C19, with IC₅₀ value >15 μM. Detailed experiments performed with human liver microsomes showed that the inhibition of CYP450 isoforms can be explained by competitive and non-competitive inhibition mechanisms. In addition, seriniquinone demonstrated to be an irreversible and time-dependent inhibitor of CYP1A2 and CYP3A. The low inhibition constants values obtained experimentally suggest that concomitant intake of seriniquinone with drug metabolized by these isoforms should be carefully monitored for adverse effects or therapeutic failure.

Creation and evaluation of a cancer chemotherapy order review guide for use at a community hospital

The proper evaluation of cancer chemotherapy orders is necessary for patients to receive safe and effective treatment. The chemotherapy treatment setting is evolving resulting in hospital pharmacists without extensive oncology training or experience now being responsible for evaluation of chemotherapy orders. The primary objective was to create a step-by-step chemotherapy order evaluation guide with a detailed explanation for each step. The secondary objective was to evaluate non-oncology trained pharmacists' ability to accurately review simulated chemotherapy orders post-education using the guide. A two-page chemotherapy order evaluation guide was created based on an accepted method of chemotherapy order review consisting of the following eight steps: regimen verification, clinical trial protocol verification, body surface area calculation, dose calculation, laboratory values, emesis prophylaxis, adjunctive or supportive care measures, and pharmacy labels. A literature search was performed for each step. A detailed explanation for each step was written as a separate component from the guide to encompass the literature search information and current guidelines in a more comprehensive manner. Non-oncology trained community hospital pharmacists were educated on use of the guide for approximately 30 min. The guide was evaluated using timed simulated chemotherapy orders pre- and post-education consisting of a general chemotherapy order and a carboplatin dosing order. Nineteen pharmacists were tested with simulated chemotherapy orders. A significant difference was detected between the pre- and post-education for both the general chemotherapy (p = 0.00032) order and carboplatin dosing order (p = 0.031).

Drug-drug interactions in pediatric oncology patients

BACKGROUND

Drug-drug interactions (DDIs) can negatively affect pharmacotherapy. However, pediatric DDI studies are scarce. We undertook an exploratory study to investigate prevalence and clinical relevance of DDIs between cytostatic and noncytostatic drugs in outpatient pediatric oncology patients.

PROCEDURE

After informed consent and inclusion, the following information was collected: currently prescribed noncytostatic and cytostatic drugs, comorbidities, and use of over-the-counter (OTC) drugs, complementary and alternative medicines (CAMs), and dietary supplements. All medication was screened for DDIs according to two databases: Micromedex^® Solutions and the Dutch drug database G-Standard. The researcher presented DDIs with an associated potential for adverse outcome and a proposal for intervention to three independent experts. If the experts considered a DDI to be potentially clinically relevant and requiring intervention, the physician was notified.

RESULTS

Seventy-three patients were included (median age 8.9 years). A total of 67 different DDIs were counted (66 in Micromedex^® Solutions, 14 in G-Standard, and 13 DDIs in both databases). The medication reviews resulted in 35 interventions related to 11 different DDIs. The majority of DDIs concerned noncytostatic drugs (25/35) and one third occurred between cytostatic and noncytostatic drugs (10/35). The use of QTc-interval-prolonging drugs resulted in one intervention. The use of OTC drugs, CAM, or dietary supplements did not lead to DDIs.

CONCLUSIONS

This study resulted in a selection of 11 potentially clinically relevant DDIs for 73 outpatients in our pediatric oncology department. Interventions were formulated in close collaboration between physicians and clinical pharmacists. Future research should focus on assessing DDIs concerning QTc-interval prolongation.

Anticancer Dose Adjustment for Patients with Renal and Hepatic Dysfunction: From Scientific Evidence to Clinical Application

Most anticancer agents exhibit a narrow therapeutic index, i.e., a small change in plasma concentrations can lead to a less efficacious treatment or an unacceptable degree of toxicity. This study aimed at providing health professionals with a feasible and time-saving tool to adapt the dose of anticancer agents for patients with renal or hepatic dysfunction. A guideline for anticancer agents was developed based on a literature search. An algorithm was generated to enhance the efficiency of the dose adaptation process. Finally, the dosing guideline was converted into an easy-to-use Excel^TM tool. The concept was applied to a total of 105 adult patients at the Centre for Integrated Oncology, Bonn, Germany. In total, 392 recommendations for dose adaptation were made and 320 (81.6%) recommendations were responded to by the oncologists. 98.4% of the recommendations were accepted. The algorithm simplifies the decision and screening process for high-risk patients. Moreover, it provides the possibility to quickly decide which laboratory tests are required and whether a dose adjustment for a particular anticancer drug is needed. The Excel^TM tool provides a recommended individual dose for patients with renal or hepatic dysfunction. The effectiveness of this strategy to reduce toxicity should be investigated in further studies before being adopted for routine use.

Association between renal function and chemotherapy-related toxicity in older adults with cancer

PURPOSE

To evaluate the association between renal function (RF) and chemotherapy-related toxicity (CRT) in older adults with cancer and to compare the effect of different RF formulas and body weight measurements on this association.

METHODS

This is a secondary analysis of data from a prospective multicenter study of patients ≥ age 65 who were starting a new chemotherapy regimen. RF was estimated with 4 formulas (modified Jelliffe [Jelliffe], Cockcroft-Gault [CG], Wright, and Modification of Diet in Renal Disease [MDRD]), using actual, ideal and adjusted body weights for 492 patients. The association between baseline RF and grade 3-5 CRT was evaluated by unconditional logistic regression.

RESULTS

As a continuous variable, decreased creatinine clearance (CrCl) calculated by CG with actual body weight was associated with increased odds of CRT (OR 1.12, P<0.01; 95% CI 1.04-1.20) indicating that on average for every 10mL/min decrease in CrCl the odds of CRT increased by 12%. Very low RF (in the lowest 10%) with all formulas (CG, Jelliffe, Wright and MDRD) was associated with increased odds for CRT. This association is independent of the type of chemotherapy received (those requiring dose adjustment for renal function vs not). Neither primary dose reduction nor chemotherapy duration was associated with CRT. Serum creatinine alone was not associated with increased odds of CRT (OR 0.67, P=0.15).

CONCLUSIONS

Decreased RF is associated with increased odds of CRT and should be considered when assessing risk of CRT in older adults with cancer. Serum creatinine alone is not adequate for risk assessment.

Consensus guidelines for optimising antifungal drug delivery and monitoring to avoid toxicity and improve outcomes in patients with haematological malignancy, 2014

Antifungal agents may be associated with significant toxicity or drug interactions leading to sub-therapeutic antifungal drug concentrations and poorer clinical outcomes for patients with haematological malignancy. These risks may be minimised by clinical assessment, laboratory monitoring, avoidance of particular drug combinations and dose modification. Specific measures, such as the optimal timing of oral drug administration in relation to meals, use of pre-hydration and electrolyte supplementation may also be required. Therapeutic drug monitoring (TDM) of antifungal agents is warranted, especially where non-compliance, non-linear pharmacokinetics, inadequate absorption, a narrow therapeutic window, suspected drug interaction or unexpected toxicity are encountered. Recommended indications for voriconazole and posaconazole TDM in the clinical management of haematology patients are provided. With emerging knowledge regarding the impact of pharmacogenomics upon metabolism of azole agents (particularly voriconazole), potential applications of pharmacogenomic evaluation to clinical practice are proposed.

Evaluation of utility of pharmacokinetic studies in phase I trials of two oncology drugs

PURPOSE

There are many phase I trials of oncology drug combinations, very few of which report clinically significant pharmacokinetic interactions. We hypothesized that the utility of such pharmacokinetic drug-drug interaction (DDI) studies is low in the absence of a mechanistic hypothesis.

EXPERIMENTAL DESIGN

We retrospectively reviewed 152 phase I (two drug) combination studies published between 2007 and 2011.

RESULTS

Only 28 (18%) studies had an implicit or explicit rationale, either inhibition/induction of a drug-metabolizing enzyme or transporter, cosubstrates for the same enzyme or transporter, potential for end-organ toxicity, or protein binding. Only 12 (8%) studies demonstrated a statistically significant DDI, on the basis of change in clearance (or area under the curve) of parent drug and/or active metabolite. There was a strong association between a rationale and a demonstrable drug interaction, as only 2% of studies without a rationale demonstrated a DDI, compared with 32% of studies with a rationale (Fisher exact test; P < 10(-6)).

CONCLUSION

DDI studies should not be routinely performed as part of phase I trials of oncology combinations.

Twelve-month frequency of drug-metabolizing enzyme and transporter-based drug-drug interaction potential in patients receiving oral enzyme-targeted kinase inhibitor antineoplastic agents

OBJECTIVE

To describe 12-month rates and patterns of coprescription of drugs that potentially create drug-drug interactions (DDIs) through shared metabolic or transport pathways for 9 enzyme-targeted kinase inhibitor oral antineoplastic drugs (OADs).

PATIENTS AND METHODS

We used a deidentified pharmacy claims database identifying patients prescribed dasatinib, erlotinib, everolimus, imatinib, lapatinib, nilotinib, pazopanib, sorafenib, or sunitinib between January 1, 2008, and May 31, 2010. Coprescribing was 1 or more overlapping days of supply between the OAD and potential DDI drugs during the 12-month period beginning on the OAD index date. Product labels identified the cytochrome P450 metabolic enzymes used and whether P-glycoprotein was used by the OADs. Drugs that induce and/or inhibit these pathways were identified from the label and online resources.

RESULTS

Sample sizes ranged from 96 (pazopanib group) to 4617 (imatinib group). Coprescribing rates with drugs that may decrease OAD effectiveness were 359/1546 (23%) (sunitinib group) to 1851/3263 (57%) (erlotinib group). Coprescribing rates with drugs that may increase OAD toxicity were 364/1546 (24%) (sunitinib group) to 71/96 (74%) (pazopanib group). Patients coprescribed DDI drugs had a median of 1 to 4 more medications present on the OAD index date than those not coprescribed a DDI drug. Most groups coprescribed DDI drugs had a median of 180 or more OAD days of supply during follow-up. The proportion of OAD days of supply with overlapping days of DDI drugs ranged from 7% to 85%. Generally, oncologists prescribed the OAD and nononcologists the DDI drug.

CONCLUSION

Coprescription of drugs that induce or inhibit metabolic pathways used by enzyme-targeted kinase inhibitor OADs is high. The clinical consequences need further study.

A novel treatment for glioblastoma: integrin inhibition

Glioblastoma (GBM) is the most common malignant primary brain tumor, which despite combined modality treatment, recurs and is invariably fatal. New therapies for GBM represent an unmet need in neuro-oncology. This review provides an overview of the epidemiology and molecular biology of GBM and focuses, in particular, on integrins, which are heterodimeric transmembrane surface proteins that, when activated, signal through several GBM-relevant pathways, including proliferation, motility, cytoskeleton organization, survival and angiogenesis pathways. Consequently, the potential effects of anti-integrin strategies in anti-GBM therapeutics are threefold: antiangiogenesis; anti-invasion; and anti-tumor. Trials of anti-integrins are most mature in GBM, and this review summarizes the completed and future trials of integrin inhibitors in the treatment of both newly diagnosed and recurrent GBM.

Novel oral anticancer drugs: a review of adverse drug reactions, interactions and patient adherence

Each aspect of oncological care is widely affected by the spread of oral anticancer agents, which raises several questions in terms of safe medication use and patient adherence. Over the past decade targeted therapies have appeared in clinical practice and revolutionized the pharmacological treatment of malignancies. Regular patient – doctor visits and proper patient education is crucial in order to comply with the therapy previously agreed upon with the oncologist, to increase patient adherence, to detect and to treat adverse effects in early stages. Since the information on the new medicines in Hungarian language is sparse it is the intention of the authors to give an overview of the basic knowledge, patient safety issues, adverse effects and interactions. Official drug information summaries and data on pharmacokinetics, interactions and adverse effects from the literature are reviewed as the basis for this overview. Orv. Hetil., 2012, 153, 66–78.

Dosing modifications of targeted cancer therapies in patients with special needs: evidence and controversies

Targeted therapies have revolutionized the treatment of malignancies over the past decade. These agents are generally regarded to posses fewer systemic side effects than traditional cytotoxic chemotherapies. However, patients manifesting organ dysfunction or drug interactions with concurrent medications may require dosing modifications of their targeted therapies in order to reduce the risk of systemic toxicities or reduction of drug efficacies. Studies have shown that wide variations and controversies exist with regard to dosing modifications of drugs, due to the lack of well conducted studies and consensus. Hence, this review was conducted to review the literature on the dosing modification strategies, for 30 commercially available targeted cancer drugs, and to evaluate the current mainstay recommendations and controversies.

Interaction between methotrexate and omeprazole in an adolescent with leukemia: a case report

We present a case of severe mucositis due to a drug-drug interaction between methotrexate (MTX) and omeprazole in an adolescent with Acute Lymphatic Leukemia (ALL). In view of the prevalence of MTX in many cytotoxic protocols, and the frequent use of omeprazole in the (ambulatory) oncology setting, we believe that this case-report is worth mentioning.

Minimising treatment-associated risks in systemic cancer therapy

Aim of the review To review the consequences of drug-related problems (DRP) in systemic cancer therapy and identify specific contributions of the pharmacist to minimise treatment-associated risks. Method Searches in PubMed, Embase and the Cochrane Library were conducted. Bibliographies of retrieved articles were examined for additional references. Only papers in English between 1980 and 2007 were included. Results In systemic cancer therapy there is an enormous potential for DRP due to the high toxicity and the complexity of most therapeutic regimens. The most frequently reported DRP can be classified into adverse effects, drug–drug interactions, medication errors, and non-adherence. Pharmacists have enhanced efforts to assure quality and safety in systemic cancer therapy together with other health care providers. In consequence, oncology pharmacy has evolved as a novel specialist discipline. The endeavour to merge and co-ordinate individual activities and services of the pharmacist has led to pharmaceutical care concepts which aim at offering novel solutions to the various DRP. Conclusion Pharmaceutical care for cancer patients should be developed within research projects and integrated into disease management programs in order to ensure broad implementation.

Drug interactions in cancer therapy

Drug interactions in oncology are of particular importance owing to the narrow therapeutic index and the inherent toxicity of anticancer agents. Interactions with other medications can cause small changes in the pharmacokinetics or pharmacodynamics of a chemotherapy agent that could significantly alter its efficacy or toxicity. Improvements in in vitro methods and early clinical testing have made the prediction of potentially clinically significant drug interactions possible. We outline the types of drug interaction that occur in oncology, the mechanisms that underlie these interactions and describe select examples.

Classification and occurrence of clinically significant drug interactions with irinotecan and oxaliplatin in patients with metastatic colorectal cancer

BACKGROUND

Pharmacokinetic and pharmacodynamic drug interactions with cytotoxic drugs may significantly influence the efficacy and toxicity of chemotherapy.

OBJECTIVE

The purpose of this study was to identify drug interactions with irinotecan and oxaliplatin reported in the literature, to assess their clinical significance, and to examine the occurrence of these interactions in patients with metastatic colorectal cancer treated with either irinotecan or oxaliplatin or both.

METHODS

To obtain data on drug-drug interactions with irinotecan and oxaliplatin, a literature search of PubMed and EMBASE was conducted using the search terms irinotecan, oxaliplatin, and interactions (English-language studies only published between 1980 and August 2004). The interactions found were subsequently classified for documentation evidence and severity of clinical effect, according to a 5-level classification system of a standard reference text, by a study panel of medical oncologists and clinical pharmacists. Comedication of patients who were treated with irinotecan or oxaliplatin, or both, was then examined to determine the occurrence of clinically significant interactions.

RESULTS

Ninety-eight patients (50 women, 48 men;mean age, 60 years) were included in the study. Seventeen interactions with irinotecan were found in the literature, and 11 were classified as clinically significant. Only 1 nonspecific, clinically significant interaction was identified for oxaliplatin. Irinotecan-treated patients received a mean of 8 different comedications and oxaliplatin-treated patients received a mean of 6. Apart from antiemetic and antidiarrheal drugs that were prescribed for treatment-related toxicities, only 1 patient appeared to be exposed to a possible clinically significant interaction (between irinotecan and phenytoin).

CONCLUSIONS

Eleven of the 17 interactions with irinotecan that were found in the literature were classified as clinically significant versus 1 clinically significant interaction with oxaliplatin. The occurrence of these interactions in the study patients with metastatic colorectal cancer was low. For medication surveillance purposes, however, the significant interactions should be considered in clinical practice.

Drug interactions in oncology

Drug interactions are an ongoing concern in treatment of cancer, especially when cytotoxic drugs are being used. However, the clinical relevance of these interactions is not always investigated. Drug interactions can be pharmaceutical, pharmacokinetic, or pharmacodynamic. They can also be wanted (eg, use of ciclosporin to enhance the oral bioavailability of paclitaxel); unwanted (eg, combination of the antiviral agent sorivudine and oral fluorouracil analogues can lead to fatal complications); between cytotoxic drugs, cytotoxic drugs and non-cytotoxic drugs; or with pharmaceutical vehicles. Potential interactions between anticancer drugs and over-the-counter or alternative medicines and herbs should not be underestimated. More attention should be given to the recognition of potential drug interactions in the preclinical and early clinical development phase of a new anticancer drug. Here, we provide a comprehensive overview of drug interactions, with selected examples.

Prevention and management of prostate cancer chemotherapy complications

Prevention and management of the adverse effects of prostate cancer chemotherapy depend on skilled regimen selection, dose adjustment, use of supportive care strategies, and a thorough understanding of the patient- and regimen-related factors that determine the risk for toxicity. Urologists, radiation oncologists, and primary care providers can play an important role before chemotherapy is prescribed by judicious use of treatments that impair bone marrow and other vital organ function. The current role of chemotherapy in prostate cancer is palliative. Successful palliation depends on reducing cancer-related suffering without introducing treatment-related suffering. Thus prevention and management of toxicity is central to the success of chemotherapy in advanced prostate cancer.