Tirbanibulin, a microtubule inhibitor, has been approved by the FDA as a 1% ointment (Klisyri – Almirall) for topical treatment of actinic keratosis of the face or scalp.

The FDA has approved sacituzumab govitecan-hziy (Trodelvy – Immunomedics), a trophoblast cell-surface antigen-2 (Trop-2)-directed antibody and topoisomerase inhibitor conjugate, for treatment of adults with metastatic triple-negative breast cancer who have received ≥2 prior therapies for metastatic disease. It is the first Trop-2-directed antibody-drug conjugate to become available in the US.

The FDA has approved the oral kinase inhibitor encorafenib (Braftovi – Pfizer), in combination with the epidermal growth factor receptor (EGFR) inhibitor cetuximab (Erbitux), for treatment of adults with metastatic colorectal cancer (CRC) with a BRAF V600E mutation. Encorafenib was approved in 2018 for use with the mitogen-activated kinase (MEK) inhibitor binimetinib (Mektovi) for treatment of unresectable or metastatic melanoma with a BRAF V600E or V600K mutation.

The FDA has approved a 10% nanoemulsion gel formulation of the porphyrin-based photosensitizer aminolevulinic acid hydrochloride (ALA; Ameluz – Biofrontera) for use in combination with a narrowband red light photodynamic therapy (PDT) lamp (BF-RhodoLED) for treatment of actinic keratoses (AKs) of mild to moderate severity on the face and scalp. A 20% ALA solution (Levulan Kerastick) approved for use in combination with blue light PDT (BLU-U) has been available in the US since 2002.

The FDA has approved the pyrimidine analog uridine triacetate (Vistogard – Wellstat Therapeutics) for emergency treatment of a fluorouracil (5-FU) or capecitabine (Xeloda, and generics) overdose or severe toxicity that occurs within 96 hours following administration of one of these drugs. Fluorouracil is a cytotoxic antimetabolite used to treat breast, colorectal, and other cancers; capecitabine is an oral prodrug of fluorouracil.

Uridine triacetate, a prodrug, is deacetylated to uridine after oral administration. Excess circulating uridine is converted into uridine triphosphate, which inhibits the cytotoxic activity of 5-fluorouridine triphosphate, a fluorouracil metabolite, by competing with it for incorporation into RNA.

FDA approval was based on two unpublished open-label studies (summarized in the package insert) in a total of 135 adults and children with overdoses of fluorouracil or capecitabine (n=117) or severe or life-threatening toxicities within 96 hours after their administration (n=18). The overall survival rate at 30 days was 96%. In retrospective case reports that included 25 patients who received only supportive care after a fluorouracil overdose, the survival rate was 16%.

Vistogard is supplied as orange-flavored oral granules in single-dose packets containing 10 grams of uridine triacetate. The granules should be mixed with 3-4 ounces of soft food and taken every 6 hours for 20 doses. The recommended dose is 10 grams for adults and 6.2 grams/m² (10 grams maximum) for children. Mild to moderate nausea, vomiting, and diarrhea have been reported. The cost for one course of treatment is $75,000.1

1. Approximate WAC. WAC = wholesaler acquisition cost or manufacturer's published price to wholesalers; WAC represents a published catalogue or list price and may not represent an actual transactional price. Source: AnalySource® Monthly. June 5, 2016. Reprinted with permission by First Databank, Inc. All rights reserved. ©2016. www.fdbhealth.com/policies/drug-pricing-policy.

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A liposomal formulation of irinotecan (Onivyde – Merrimack) has been approved by the FDA for use in combination with fluorouracil and leucovorin for treatment of metastatic pancreatic cancer that has progressed after gemcitabine-based therapy. A non-liposomal formulation of irinotecan (Camptosar, and generics) has been available in the US for many years. The liposomal carrier prolongs exposure to irinotecan and improves the cellular uptake and cytotoxic effect of the drug.1

FDA approval of liposomal irinotecan was based on the results of an open-label trial (NAPOLI-1) in 417 patients with metastatic pancreatic ductal adenocarcinoma whose disease progressed after gemcitabine-based therapy. Patients were randomized to receive either liposomal irinotecan alone, fluorouracil and leucovorin alone, or liposomal irinotecan in combination with fluorouracil and leucovorin. Median overall survival, the primary endpoint, was significantly longer with all three drugs (6.1 months), compared to fluorouracil and leucovorin alone (4.2 months) and liposomal irinotecan alone (4.9 months). The most frequent severe (grade 3 or 4) adverse effects of the liposomal irinotecan-containing regimen were neutropenia, diarrhea, vomiting, and fatigue.2 Life-threatening diarrhea has also occurred in patients receiving the 3-drug combination.

Onivyde is available in 43 mg/10 mL single-dose vials. The recommended dosage is 70 mg/m² administered intravenously over 90 minutes every 2 weeks; leucovorin and fluorouracil should be administered after liposomal irinotecan. The recommended starting dose of Onivyde for patients who are homozygous for the UGT1A1*28 allele is 50 mg/m²; the dose can be increased to 70 mg/m² as tolerated. The labeling specifies a number of dosage adjustments that should be made when adverse effects occur. One dose of Onivyde costs $4860.3

1. A Casadó et al. Formulation and in vitro characterization of thermosensitive liposomes for the delivery of irinotecan. J Pharm Sci 2014; 103:3127.
2. A Wang-Gillam et al. Nanoliposomal irinotecan with fluorouracil and folinic acid in metastatic pancreatic cancer after previous gemcitabine-based therapy (NAPOLI-1): a global, randomised, open-label, phase 3 trial. Lancet 2016; 387:545.
3. Approximate WAC for a patient with a 1.7 m² surface area. WAC = wholesaler acquisition cost or manufacturer’s published price to wholesalers; WAC represents a published catalogue or list price and may not represent an actual transactional price. Source: AnalySource® Monthly. May 5, 2016. Reprinted with permission by First Databank, Inc. All rights reserved. ©2016. www.fdbhealth.com/policies/drug-pricing-policy.

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The FDA has approved the pyrimidine analog uridine triacetate (Xuriden [zur' uh den] – Wellstat Therapeutics) for treatment of hereditary orotic aciduria, a rare autosomal recessive disorder (estimated birth prevalence: <1:1,000,000) in infants and children caused by a deficiency in uridine 5'-monophosphate (UMP) synthase. This deficiency prevents synthesis of uridine nucleotides and causes developmental delays, failure to gain weight, hematologic abnormalities, and excessive urinary excretion of orotic acid, which can lead to urinary obstruction.1 Xuriden is the first drug to be approved in the US for this indication. Uridine triacetate is also available as Vistogard for treatment of fluorouracil (5-FU) or capecitabine (Xeloda, and generics) overdose or severe or life-threatening toxicity.

In an unpublished, single-arm, 6-week trial with a 6-month extension (summarized in the package insert), 4 patients 3-19 years old with hereditary orotic aciduria were treated with uridine triacetate 60 mg/kg once daily for 6 weeks, followed by 60-120 mg/kg once daily for 6 months. After 6 months of treatment, hematologic parameters (neutrophil count, WBC count, or mean corpuscular volume) either improved or remained stable and orotic acid levels remained stable in all 4 patients. Weight growth either improved or remained stable and height growth remained stable in 3 patients measured after 6 months of treatment. No adverse effects were reported.

Xuriden is available as oral granules in 2-gram single-use packets. The recommended starting dosage is 60 mg/kg once daily. The dose can be increased to 120 mg/kg (max 8 grams) once daily if urine orotic acid levels increase or remain above normal, or for worsening disease. The granules should be mixed in applesauce, pudding, yogurt, milk, or infant formula and swallowed immediately, without chewing. Once the packet is opened, any unused granules should be discarded. The cost for 30 2-gram packets of Xuriden is $22,500.2

1. S Balasubramaniam et al. Inborn errors of pyrimidine metabolism: clinical update and therapy. J Inherit Metab Dis 2014: 37:687.
2. Approximate WAC = wholesaler acquisition cost, or manufacturer's published price to wholesalers; WAC represents published catalogue or list prices and may not represent an actual transactional price. Source: AnalySource® Monthly. March 5, 2016. Reprinted with permission by First Databank, Inc. All rights reserved. ©2016. www.fdbhealth.com/policies/drug-pricing-policy.

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The FDA has approved Akynzeo (Helsinn/Eisai), an oral fixed-dose combination of the substance P/neurokinin 1 (NK₁) receptor antagonist netupitant and the serotonin-3 (5-HT₃) receptor antagonist palonosetron, for prevention of acute and delayed nausea and vomiting associated with cancer chemotherapy in adults. Akynzeo is the first product to combine drugs from these two classes. Palonosetron (Aloxi) is also available as a single agent for prevention of chemotherapy-induced and postoperative nausea and vomiting. Netupitant is the second substance P/NK₁ receptor antagonist to be approved in the US; aprepitant (Emend) was the first.

The treatment of atrial fibrillation includes anticoagulation, rate control, and rhythm control. New US guidelines for the management of atrial fibrillation have recently been published.

The FDA has approved ingenol mebutate (Picato – Leo) for topical treatment of actinic keratoses (AKs). The new drug is derived from the sap of the Euphorbia peplus plant, a traditional folk remedy for warts and other skin lesions.

A reader expressed disappointment that our recent listing of “Some Warfarin Drug Interactions”1 did not include acetaminophen. Perhaps it should have. Acetaminophen can increase the anticoagulant effect of warfarin, particularly with continued use, but it does so inconsistently. The mechanism of this interaction has not been established, but may be related to an acetaminophen metabolite inhibiting vitamin K-epoxide reductase, the target for warfarin’s anticoagulant effect.2

Patient susceptibility varies, possibly on a genetic basis; occasional use of acetaminophen generally has little or no effect on the international normalized ratio (INR) in patients on chronic warfarin therapy, but in some, even a few grams of the drug may cause a dramatic increase in INR. One study in healthy subjects found no effect of acetaminophen 4 g per day for 2 weeks, while another study in patients with the same acetaminophen dose for the same period of time found a moderate increase in INR.3,4 It might be prudent to monitor INR in patients on chronic warfarin therapy more closely than usual when they take more than 2 g per day of acetaminophen for more than a few days.

1. Pharmacogenetic-based dosing of warfarin. Med Lett Drugs Ther 2008; 50:39.
2. HH Thijssen et al. Paracetamol (acetaminophen) warfarin interaction: NAPQI, the toxic metabolite of paracetamol, is an inhibitor of enzymes in the vitamin K cycle. Thromb Haemost 2004; 92:797.
3. D Kwan et al. The effects of acetaminophen on pharmacokinetics and pharmacodynamics of warfarin. J Clin Pharmacol 1999; 39:68.
4. I Mahe et al. Paracetamol: A haemorrhagic risk factor in patients on warfarin. Br J Clin Pharmacol 2005; 59:371.

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Warfarin sodium (Coumadin, and others) and other coumarin anticoagulants prevent thrombosis, but patient response is highly variable and overanticoagulation can lead to hemorrhage. Genotyping patients for single nucleotide polymorphisms (SNPs) that affect coumarin metabolism and sensitivity may help clinicians estimate the therapeutic warfarin dose. The FDA has added a note to warfarin labeling recommending lowrange doses for patients with such genetic variations. Commercial tests for these variants are now available and cost about $500 per test.

A variety of cancer chemotherapy drugs are used, mostly in combination, for treatment of locally advanced and metastatic esophageal, gastric and colorectal cancers. The mechanism of action, indications and adverse effects of some of these drugs are discussed in thei article.

In addition to surgery and radiation therapy, a variety of drugs are used both singly and in combination to treat breast cancer. This article summarizes the principles of adjuvant therapy and treatment for metastatic disease. A summary of individual drugs and their adverse effects begins on page 3.

Tinidazole (Tindamax - Presutti Labs), an oral antiprotozoal drug similar to metronidazole (Flagyl, and others), has been approved by the FDA for treatment of trichomoniasis in adults and for treatment of giardiasis, intestinal amebiasis and amebic liver abcess in adults and children more than 3 years old. Tinidazole has been widely used outside of the US for decades under the trade name Fasigyn (Pfizer).

Cetuximab (Erbitux - ImClone Systems/Bristol-Myers Squibb), an epidermal growth factor receptor (EGFR) inhibitor, and bevacizumab (Avastin - Genentech), the first vascular endothelial growth factor angiogenesis inhibitor, have recently been approved by the FDA for treatment of patients with metastatic colorectal cancer. Cetuximab is approved for treatment of patients with EGFR-expressing tumors, either in combination regimens with irinotecan (Camptosar)when the cancer has progressed on irinotecan-based therapy, or as monotherapy for those who cannot tolerate irinotecan. Bevacizumab is approved for first-line therapy in combination with a fluorouracil-based regimen.

Imiquimod cream 5% (Aldara - 3M), an immune modifier previously approved for treatment of genital and perianal warts (Medical Letter 1997; 39:118), has now been approved by the FDA for treatment of actinic keratoses (AKs) on the face or scalp, and may also be approved soon for treatment of basal cell carcinoma. It produces apoptosis in malignant, but not normal, human keratinocytes (M Sch÷n et al, J Natl Cancer Inst 2003; 95:1138).

Aprepitant (Emend - Merck), the first substance P/neurokinin 1 (NK₁) receptor antagonist to be approved by the FDA, is now available for oral use with corticosteroids and selective serotonin (5-HT₃) receptor antagonists to prevent nausea and vomiting caused by highly emetogenic anticancer drugs such as cisplatin.

The tables in this article list drugs used for treatment of cancer in the USA and Canada and their major adverse effects. The choice of drugs in Table I is based on the opinions of Medical Letter consultants. Some drugs are listed for indications for which they have not been approved by the US Food and Drug Administration. In some cases, such as elderly patients or those with many co-morbid illnesses, the regimen of choice might not be suitable. For many of the cancers listed, surgery and/or radiation therapy may be the treatment of choice or may also be part of the management. Anticancer drugs and their adverse effects are listed in Table II on page 46. A partial list of brand names appears on page 52.

Oxaliplatin (Eloxatin -Sanofi-Synthelabo) has been approved by the FDA for use in combination with fluorouracil (5-FU; Adrucil, and others) and leucovorin (LV; Wellcovorin) for patients with metastatic colorectal cancer whose disease has recurred or progressed despite treatment with 5-FU/LV plus irinotecan (Camptosar - Medical Letter 1997; 39:8).

Several new treatments are now available for actinic keratoses (AKs), scaly pink papules commonly found on sun-exposed areas of the face, scalp, forearms and dorsal surface of the hands, particularly in the elderly. Some AKs regress spontaneously, but a few may progress to squamous cell carcinoma; the risk of progression has been estimated to be about 0.25% to 1% per year (EWB Jeffes III and EH Tang, Am J Clin Dermatol 2000; 1:167).

The tables in this article list drugs used for treatment of cancer in the USA and Canada. The choices of drugs in Table 1 is based on the opinions of Medical Letter consultants. Some drugs are listed for indications for which they have not been approved by the US Food and Drug Administration. For many of the cancers listed, surgery and/or radiation therapy are also part of the management of the disease.

Epirubicin, an analog of doxorubicin that has been available in Europe and Canada for 15 years, has now been approved by the FDA for adjuvant use after resection of the primary tumor in breast cancer patients with axillary node involvement.

Imiquimod (i mi kwi' mod) 5% cream (Aldara - 3M Pharmaceuticals) has been approved by the FDA for treatment of external genital and perianal warts (condyloma acuminata). The drug requires a prescription but is applied by the patient. It is the second patient-applied treatment to become available for external genital warts; the first was podofilox (Condylox - Medical Letter, 33:117, 1991).

The tables that follow list drugs used for treatment of cancer in the USA and Canada and their major adverse effects. The choice of drugs in Table I is based on the opinions of Medical Letter consultants. Some drugs are listed for indications for which they have not been approved by the US Food and Drug Administration. For most of the cancers listed, surgery and/or radiation therapy are part of the management of the disease. Anticancer drugs and their adverse effects are listed in Table II.

Irinotecan hydrochloride (Camptosar - Pharmacia & Upjohn; formerly CPT-11) has been approved by the US Food and Drug Administration for treatment of metastatic colorectal cancer refractory to other drugs including fluorouracil (5-FU; Adrucil and others).

Gemcitabine (jem site a been) hydrochloride (Gemzar - Lilly), a nucleoside analog, has been approved by the US Food and Drug Administration for intravenous (IV) use in the first-line treatment of locally advanced or metastatic adenocarcinoma of the pancreas and in patients with pancreatic cancer previously treated with fluorouracil (Adrucil, and others). No previously available drug has had more than minor activity in treating this disease.

Several currently available antiemetic drugs can prevent vomiting caused by cancer chemotherapy. Anticancer drugs that cause vomiting are listed in the table below.

Masoprocol cream 10% (meso-nordihydroguiaretic acid, Actinex - Reed and Carnrick) is now available in the USA for topical treatment of actinic keratoses.

Podofilox 0.5% solution (Condylox - Oclassen) was recently approved by the US Food and Drug Administration for treatment of (condylomata acuminata). The drug requires a prescription, but is labeled for application by the patient. Similar topical solutions previously available for this indication are approved only for application by the physician.

Recent studies have caused concern about cardiomyopathy associated with doxorubicin (Adriamycin, and others), daunorubicin (Cerubidine, and others), idarubicin (Idamycin), mitoxantrone (Novantrone), and related anthracycline or anthraquinone anticancer drugs. Dexrazoxane (ADR-529, ICRF-187 - Adria), a piperazine derivative of ethylenediaminetetraacetic acid (EDTA), is now under investigation for prevention of this drug-induced cardiomyopathy.

Ondansetron (on dan' se tron; Zofran - Glaxo), a serotonin (5-hydroxytryptamine) antagonist, was recently marketed in the USA for intravenous use to prevent nausea and vomiting due to cancer chemotherapy. An oral formulation is available in many other countries.

The most important prognostic variable in early breast cancer is axillary lymph node involvement. Based on past experience, after 10 years about 70% of node-negative patients will be alive and apparently free of disease; about 30% will have relapsed or died. Patients with positive nodes may have a 30% to 60% relapse rate, depending on the number of positive nodes and other prognostic factors, such as the presence of estrogen receptors (IC Henderson et al, in VT DeVita, Jr et al, eds, Cancer: Principles and Practice of Oncology, 3rd ed, Philadelphia:Lippincott, 1989, p 1197). Which of these patients should receive adjuvant treatment with cytotoxic drugs and/or endocrine therapy is controversial; a National Cancer Institute (NCI) Consensus Conference on this subject is scheduled for June.

Levamisole (Janssen), an old antiparasitic drug widely used for treatment of ascariasis in animals, is now available from the National Cancer Institute (NCI) for investigational use with fluorouracil (5-FU; Adrucil; and others) as an adjuvant for treatment of resectable colon cancer that has metastasized to regional lymph nodes (Dukes stage C).

Carboplatin (Paraplatin - Bristol-Myers), a cytotoxic platinum-containing drug chemically related to cisplatin (Platinol), was recently approved by the US Food and Drug Administration (FDA) for palliative treatment of patients with recurrent ovarian cancer, including those previously treated with cisplatin.

Recombinant interferon alfa-2b (Intron A - Schering) was recently approved by the US Food and Drug Administration (FDA) for intralesional treatment of genital warts (condylomata acuminata). Interferon was previously available only for treatment of hairy-cell leukemia (Medical Letter, 28:78, 1986).