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Practical Oncology Principles of Chemotherapy

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1 Practical Oncology Principles of Chemotherapy
Wendy Blount, DVM

2 Indications for Chemotherapy
Systemic or metastatic disease that is chemo responsive local control (surgery, radiation therapy) isn’t adequate Cure is rare (TVT is an exception) Remission or prolonged stable disease is likely Months to years Prepare owners for relapse that will ultimately be unmanageable Neo-adjuvant therapy Reducing size of large, localized tumor prior to surgery Dirty borders on localized tumor Increased survival time without decreasing quality of life

3 Metronomic Therapy Fewer side effects than high dose treatment
Cyclophosphamide and piroxicam to prevent recurrence of sarcomas Cyclophosphamide 10 mg/m2 PO SID or QOD Piroxicam 0.3 mg/kg PO SID or QOD Take care that the pet is not also on prednisone Low dose chlorambucil is also considered metronomic

4 Side Effects Make sure clients understand that chemo protocols for animals are much less aggressive than for people Side effects are assumed to be present and possibly severe for people Many pets who undergo chemotherapy have infrequent side effects that are often mild Chemo drugs kill or harm cells that divide rapidly Gastrointestinal tract, bone marrow, skin and hair The most common side effects are gastrointestinal, pancytopenias (mostly WBC) and changes in fur Dogs may be unable to reproduce after chemotherapy

5 Side Effects GI Toxicity Direct damage to epithelial cells
3-5 days after chemo Direct stimulation of the chemoreceptor trigger zone 24-48 hours after chemo Both - inappetance, nausea, vomiting, diarrhea Can vary from a few soft stools to parvovirus-like disease Dispense Cerenia and Metronidazole at the first treatment if you anticipate a problem with getting the meds on the day needed

6 Side Effects Bone Marrow Toxicity Direct damage to stem cells
Neutrophils have shortest life, so they are affected first Then other WBC, platelets and RBC Delay chemo if Neutrophils <2,000/ul recheck CBC 3-7 days Antibiotic therapy if fever or neutrophils <1,000/ul GCSF (Neupogen®) if neutrophils <500/ul IV fluids and IV antibiotics only if septic Placing an IV catheter in an asymptomatic neutropenic dog can result in infection or sepsis

7 CBC the day of and prior to every chemo dose
Side Effects Bone Marrow Toxicity Delay chemo if platelets <50,000, unless Tpenia is thought to be caused by neoplasia If cytopenia, delay treatment by 3-7 days and reduce dose by 20-25% when resumed Most chemo delay by 3-7 days Lomustine*, doxorubicin, cyclophosphamide*, chlorambucil delay at least 7 days CBC the day of and prior to every chemo dose Draw from the jugular vein

8 Side Effects Bone Marrow Toxicity Nadirs – recovery usually within 7 days (*these drugs longer) Not usually myelosuppressive – L-asparaginase 4-6 days - methotrexate 5-7 days - cytarabine 7-10 days – doxorubicin*, mustargen, procarbazine 10 days – mitoxantrone 7-14 days – chlorambucil*, cyclophosphamide** 14 days – carboplatin (cats days) 7-21 days – lomustine**

9 Side Effects Hair Loss Fur might thin or change color, but complete hair loss is rare Fur loss is more common with non-shedding dogs such as poodles and terriers Their fur continuously grows Cats may lose guard hairs or whiskers

10 Have 2 staff members calculate the dose, and compare
Overdose Be very careful to use kg not lb when converting body weight to Body Surface Area. Using lb will result in 2x chemotherapy dose If given PO, induce vomiting immediately This mistake is almost always fatal if given by injection Have 2 staff members calculate the dose, and compare A 60 lb dog is about 1m2 = 0.6cc vincristine, 15cc doxorubicin, 40mg prednisone, 60mg CCNU, mg cyclophosphamide (8-10 small tablets, 4-5 large tablets) 1 vial Elspar

11 Patient Care Chemotherapy patients should never be given MLV vaccines (risk of post-vaccinal infection) Vaccinations with killed vaccines (rabies) should be fine Clients should be furnished with gloves to wear For administering chemo pills for cleaning up pet eliminations When sitting with animals during IV drips Always provide a written educational handout for each drug given (

12 Safe Handling Order liquid injectables rather than those that must be reconstituted Doxorubicin, vincristine, vinblastine, carboplatin, mitoxantrone Have oral chemo doses professionally compounded ALWAYS WEAR GLOVES!! Chemo gloves or double latex gloves Wear a respirator mask if you must reconstitute powders Cytosar-U, Actinomycin-D, dacarbazine (not Elspar) Inject bubbles out of the syringe prior to removing the needle from the vial Put anything that touched the drug in biohazard disposal

13 Safe Handling Reconstitute drugs in a biological safety cabinet
Have your local pharmacist do it for you Use venting devices or drug filters to avoid aerosolization when withdrawing needle from the vial Wear an isolation gown, buttoned lab coat, etc. Wear eye protection Oncology nurses have higher incidence of headaches and nausea Skin irritation Chromosomal, bone marrow and liver damage Miscarriage and cancer

14 None are damaged by refrigeration
Keep Refrigerated Doxorubicin Vincristine, Vinblastine Elspar Chlorambucil Cytarabine once reconstituted Dacarbazine None are damaged by refrigeration

15 MDR-1 Deletion White Feet – Don’t Treat
Test for MDR1 deletion before giving these drugs to collies: (form) Doxorubicin, D-actinomycin Vincristine, Vinblastine Do not give drugs that inhibit p-glycoprotein concurrently Comfortis or Trifexis Ca++ channel blockers (amioderone, diltiazem, verapamil, carvedilol) Azole antifungals Cyclosporin Lincosamides (azithromycin, clarithromycin, erythromycin)

16 IV Push Chemotherapy For drugs that are given IV quickly -
Vincristine, mitoxantrone Flush butterfly catheter (19-22 gauge) with sterile fluid compatible with the drug Place it on the glove envelope used as sterile field Predraw syringes – two 4-6cc fluid for flush, plus drug; remove needles and place on sterile field Clip and gently clean the skin Assistant occludes and rolls the vein, to release when instructed Place butterfly catheter on clean stick, do not tape Flush/test, inject drug, flush/test Remove butterfly catheter and bandage leg

17 IV Drip Chemotherapy For drugs that are given IV slowly – more than a minute or two Doxorubicin, mustargen, actinomycinD, carboplatin, (vinblastine) Attach buretrol and IV line to compatible IV fluid bag and hang Draw up chemo to be given Clip and gently clean the skin Place and secure IV catheter on clean stick

18 IV Drip Chemotherapy Trained trusted assistant sits with dog during drip If any problems, stop drip and then get help Run 20-50cc fluids into Buretrol and run into patient to test line patency If problems, place another catheter Add chemo drug to Buretrol and qs to 2ml/minute e.g., vinblastine given over 10 minutes, qs to 20 ml Run 2-3 aliquots of 10-20cc IV fluids into the buretrol and then into the patient, until fluid runs clear when drug is colored Remove IV catheter and bandage

19 Wicked Expensive Drugs
Mustargen (<$700 for a 4-pack) Palladia and Kinavet (>$500 a month for medium dog) Gleevex ($100 a pill) Procarbazine (>$1000 last time I checked) Doxil – liposomal doxorubicin – 20x cost of doxorubicin Try Diamondback Pharmacy for all but TKIs Try Medshoppe Pharmacy in Longview for back ordered items


21 Alkylating Agents Orally or by IV injection or drip
Efficacy not affected by route of administration Cyclophosphamide (Cytoxan®, Neosar®) Chlorambucil (Leukeran®) Lomustine, aka CCNU (Ceenu®) Melphalan (Alkeran®) Mustargen (Mustine®) Procarbazine (Matulane®) Dacarbazine, (DTIC-Dome®)

22 Cyclophosphamide Dose: 200-250 mg/m2 PO or IV
Can give in one dose, or divide into 3-5 daily doses Indications: LSA, leukemias, carcinomas, sarcomas Unique side effects: Can cause sterile hemorrhagic cystitis (CIC) Can predispose to transitional cell carcinoma If not on prednisone, add furosemide 1 mg/lb given with each cyclophosphamide dose Negative urine culture diagnoses CIC If cystitis, discontinue and replace with chlorambucil Give in the morning & encourage frequent bladder emptying Give with food to prevent stomach upset

23 Cyclophosphamide Unique side effects: Drug Interactions:
Rarely can cause pneumonitis Cleared by liver and kidneys – use with caution in pets with liver or kidney disease Drug Interactions: Allopurinol an increase bone marrow toxicity Doxorubicin can increase cardiotoxicity Chloramphenicol, imipramine, phenobarbital, phenothiazines, KI, thiazide diuretics and vitamin A can enhance toxicity Handling: Injectable is good for 14 days if refrigerated, once mixed (label says 6 days)

24 Chlorambucil Dose: 15-20 mg/m2 PO SID or QOD x 4 days, repeat q3 weeks
If sterile cystitis in response to cyclophosphamide occurs, substitute chlorambucil 15 mg/m2 PO SID x 4 days 6-8 mg/m2 PO QOD for chronic therapy in dogs & cats Indications: leukemias, myeloma, indolent lymphomas Unique Side Effects: Liver toxicity, Pneumonitis Handling: Keep refrigerated Exterior coating is sweet – keep away from pets and children

25 Lomustine Dose: 60-70 mg/m2 PO, q3-4 weeks
Doses of 90 mg/m2 are published, but Barton says she has never given this high dose without sepsis Kevin Hahn uses 40 mg/m2 every 2 weeks Premedicate with diphenhydramine Indications: MCT, LSA Rescue, histiocytic sarcoma, CNS tumors, canine skin lymphoma Unique Side effects: Prolonged and cumulative myelosuppression No other chemo for 3-4 weeks First dose should have a 4 week treatment interval If subsequent doses show recovery by 3 weeks, interval can be reduced to 3 weeks

26 Lomustine Unique Side effects: 2. Can cause hepatotoxicity
Serum panel prior to the first dose Bile acids if significant liver disease is suspected Choose another drug if bile acids significantly elevated Check panel prior to third dose and every other dose thereafter Discontinue if and when ALT climbs or albumin falls significantly Often discontinued after 6-12 doses SAMe and silymarin may mediate hepatotoxicity Eliminated by the kidneys - Reduce dose in animals with kidney disease; possible renal toxicity Give with food to reduce stomach upset Rare stomatitis , corneal ulcers or pneumonitis

27 Melphalan Indications: LSA rescue (DMAC), myeloma, sarcoma, carcinoma, FIP Unique Side Effects: Pneumonitis, pulmonary fibrosis Use with caution with kidney disease – reduce dose by 50% neurotoxicity Drug Interactions: Kidney toxicity when used with cyclosporine

28 Melphalan Multiple Myeloma Protocol, with prednisone Or Pulse Therapy
0.1 mg/kg PO SID x 10 days, then 0.05 mg/kg PO QOD thereafter Prednisone 0.5 mg/kg PO SID x 10d, then QOD Or Pulse Therapy 7 mg/m2 PO SID x 5 days, repeat every 3 weeks Some add single dose cyclophosphamide – 200 mg/m2 IV Monitor globulins for response to therapy Also resolution of symptoms Lameness, bleeding diathesis, retinal lesions

29 Melphalan CLL for cats – 2 mg/m2 PO QOD + prednisone 20 mg/m2 QOD
Any chronic melphalan therapy CBC q2 weeks x 2 times Then once a month Also comes as an injectable – different protocol

30 Mustargen Dose: 3 mg/m2 IV over 10 minutes
Indications: LSA Rescue, intracavitary injections for neoplastic effusions Unique Side Effects: Urate stone formation in Dalmations Hearing loss with Liver toxicity Peripheral neuropathy – weakness, ileus, constipation GI ulceration Sloughing if extravasated

31 Mustargen Drug Interactions: allopurinol dose may need to be increased
Handling: Mix and administer immediately – it is inactive within an hour Draw up dose and dilute to 12 ml with saline Then give IV over 10 minutes

32 Procarbazine Dose: 50 mg/m2 PO SID x 14 days
Indications: LSA Rescue, GME, Brain tumors Unique Side Effects: Use with caution with liver disease, kidney disease, heart disease, urate stones Nausea – give concurrently with Cerenia Neurotoxicity – seizures, ataxia Peripheral neuropathy – ileus, constipation, stumbling stomatitis

33 Procarbazine Drug Interactions:
Potentiates activity of CNS depressants anticonvulsants, opiates, sedatives, antihistamines, antihypertensives, tricyclic antidepressants Serious hypertension if given with sympathomimetics Phenylpropanolamine Avoid foods high in tyramine – aged cheese, yogurt, bananas Contraindications: any of the above drugs Handling: OK to compound into capsules, but liquids must be oil based

34 Dacarbazine Dose: 800-1000 mg/m2 IV over 5-8 hours q2-3 weeks
Pretreat with Cerenia Pretreat with dexamethasone to prevent phlebitis Pretreat with opiate to prevent pain on IV infusion Indications: LSA Rescue, ST sarcoma, melanoma Unique Side Effects: Serious extravasation injury, like Actinomycin D Hepatoxicity and nephrotoxicity - use with caution with hepatic or renal disease Photosensitivity Dilute to prevent pain on IV infusion (D5W or saline)

35 Dacarbazine Contraindications: not for use in cats, as there is no evidence cats can metabolize it in the liver Handling: Keep refrigerated Use within 8 hours of reconstituting at room temperature and 72 hours if refrigerated I do not use this drug, as it is causes severe injury on extravasation and I can not have a tech sit with a dog for 5-8 hours to manage an IV drip. It may work well in a practice with ICU supervision.


37 Antitumor Antibiotics
by intravenous drip Doxorubicin (Adriamycin®) Mitoxantrone (Novantrone®) Actinomycin-D, dactinomycin (Cosmegen®) Bleomycin (Doxycycline) Decreases metalloproteinases, which break down intracellular matrix allowing tumor invasion Antioangiogenic effects

38 Doxorubicin – “Red Death”
Dose: mg/m2 IV over 20 minutes, q2-3 weeks Premedicate with diphenhydramine and Cerenia 1 mg/kg if less than 15 kg Indications: LSA, leukemia, carcinomas, sarcomas Unique Side Effects: Severe necrosis leading to amputation or death due to cardiotoxicity if extravasated More likely to cause GI signs and malaise than the other drugs in CHOP protocols Often the last drug to lose effectiveness in CHOP Toxicity can be somewhat cumulative – may need to reduce dose with time Prolonged myelosuppression – check CBC at 10 days post Tx

39 Doxorubicin – “Red Death”
Unique Side Effects: Hypersensitivity – allergy to one brand may not be to others Cardiotoxicity Acute cardiotoxicity – cardiac arrest during or several hours after chemotherapy Cumulative cardiotoxicity precludes further use of doxorubicin can occur as low as 90 mg/m2 total dose 6% of dogs with 5+ doses Nephrotoxicity in cats monitor BUN, creat, phos Urinalysis - casts Increased toxicity in dogs with MDR-1 Deletion Reduce dose by 30%

40 Doxorubicin – “Red Death”
Drug Interactions: Actinomycin-D and Ca channel blockers increase cardiotoxicity Diltiazem Verapamil Cyclophosphamide, cyclosporine increase doxorubicin levels Phenobarbital & glucosamine may reduce doxorubicin levels Contraindications: Myocardial failure echocardiogram prior to giving doxorubicin to Dobermans, Great Danes and Boxers or if heart murmur Dogs and Cats with renal failure Dogs with MDR-1 deletion (reduce dose by 30%)

41 Doxorubicin – “Red Death”
Handling: refrigerate and protect from light Irritating to the skin – wash well if exposed Special Client Communications: Prior permission to take immediately to surgery if extravasated Warn of cardiotoxicity – acute and cumulative GET PERMISSION TO USE THIS DANGEROUS DRUG

42 Doxorubicin – “Red Death”
Lifetime Total Dose: should not exceed mg/m2, unless cardioprotective drugs are given Check echocardiogram prior to each dose >150 mg/m2 Should never exceed 240 mg/m2, or cardiotoxicity is likely Liposomal doxorubicin (Doxil) Reduces cumulative cardiotoxicity Can be used after total lifetime doxorubicin dose has been reached Cost is 20x that of native doxorubicin Overcoming resistance with dacarbazine (see LSA Rescue Handout)

43 Doxorubicin Extravasation
Some believe you should take the dog right to surgery and cut out the red stuff Give Zinecard (dexrazoxane) mg/m2 IV within 2-3 hrs of extravasation through a different IV catheter Repeat at 24 and 48 hours Zinecard can near 100% protection from slough and acute fatal cardiotoxicity Ice pack 15 minutes every 6 hours for 48 hours Apply DMSO 99% to area 2x extravasation q6hrs x 14 days Doxorubicin is a double edged sword

44 Mitoxantrone – “Blue Thunder”
Dose: mg/m2 IV every 2-3 weeks Indications: LSA, carcinomas, hemangiopericytoma Safer for cats with renal failure than doxorubicin Combining with dacarbazine (DTIC) may increase effectiveness for rescue therapy Unique Side Effects: Use with caution in hepatic disease Conjunctivitis Jaundice, renal failure Irritation if extravasated Green-blue urine for up to 5 days

45 Mitoxantrone – “Blue Thunder”
Drug Interactions: Increased dose of allopurinol may be needed Enhanced cardiotoxicity if previous doxorubicin, daunorubicin or radiation therapy Precipitates in contact with heparin Contraindications: myocardial failure, though cardiotoxicity not yet reported in dogs as in people

46 Actinomycin-D Dose: 0.5-1 mg/m2 IV over 20 minutes, q2-3 weeks
Premedicate with diphenhydramine and Cerenia Indications: LSA Rescue, OSA Unique Side Effects: Necrosis if extravasated GI ulceration or stomatitis Increases uric acid – avoid in urate stone formers Possible hepatotoxicity – monitor liver enzymes every 2-3 doses Cardiotoxicity – echo after 4-6 doses

47 Actinomycin-D Drug Interactions: Contraindications:
Additive cardiotoxicity with doxorubicin Contraindications: hepatic dysfunction Dogs with MDR-1 deletion (reduce dose by 30%) Handling: use immediately and discard unused portion

48 Platinum Drugs by intravenous drip Carboplatin (Paraplatin®) Cisplatin

49 Carboplatin Dose: mg/m2 IV over 15 minutes q3 weeks in dogs mg/m2 IV over 15 minutes q3-4 weeks in cats Has been given intratumorally for nasal planum SCC in cats Intracavitary for mesothelioma Indications: carcinomas (not TCC), sarcomas, OK for cats Unique Side Effects: Anorexia or vomiting at 2-4 days Used cautiously if hepatic or renal disease Hearing impairment

50 Carboplatin Drug Interactions: Handling:
increased nephrotoxicity and ototoxicity of aminoglycosides Increased likelihood of MLV vaccine induced disease Handling: dilute in D5W, saline or sterile water Once reconstituted, use within 8 hours Black precipitate will form if it comes into contact with aluminum

51 Vinca Alkaloids by intravenous injection or drip
Vincristine (Oncovin®) Vinblastine (Velban®)

52 Vincristine Dose: 0.5-0.75 mg/m2 IV push
Indications: LSA, leukemias, thrombocytopenia, TVT Unique Side Effects: Peripheral neuropathy - ileus, constipation, dropped hocks Slough if extravasated (not as severe as doxorubicin) Infiltrate with dexamethasone or DMSO Rare severe GI side effects in cats Reduce dose by 50% if icteric (cats with LSA can be) Use with caution with liver or musculoskeletal disease Reduce dose by 25-30% in MDR1 deletion dogs

53 Vincristine Drug Interactions: Contraindications: severe liver disease
Toxicities increased by drugs that inhibit p-glycoprotein Comfortis or Trifexis Ca++ channel blockers (amioderone, diltiazem, verapamil, carvedilol) Azole antifungals Cyclosporin Lincosamides (azithromycin, clarithromycin, erythromycin) Contraindications: severe liver disease Handling: keep refrigerated

54 Vinblastine Dose: 2-2.2 mg/m2 IV over 10 minutes
Nausea, pallor, vomiting if given too fast Indications: LSA, MCT, carcinomas Developed to avoid vincristine associated neuropathy (dogs) Unique Side Effects: More myelosuppressive than vincristine The rest like vincristine Nausea, vomiting for 24 hours Drug Interactions/Contraindications: same as vincristine Handling: keep refrigerated

55 Antimetabolites Cytarabine, cytosine arabinoside (Cytosar-U®)
Methotrexate 5-Fluouracil

56 Cytarabine Dose: mg/m2 IV drip over 4 hours or SQ divided q1 hour x 4 Premedicate with Cerenia Indications: leukemias, CNS LSA, feline renal LSA Unique Side Effects: More myelosuppression with IV administration stomatitis, conjunctivitis Rare liver toxicity

57 Cytarabine Drug Interactions: Handling:
May decrease absorption of digoxin for several days May decrease efficacy of gentocin Handling: good for 17 days after reconstituting if refrigerated hazy solution should be discarded. Serum panel/lytes and urinalysis every 3 months minimum on chemo patients

58 Tyrosine Kinase Inhibitors
by mouth – covered under lymphoma Palladia® Kinavet® Gleevex®

59 Corticosteroids by mouth or by injection Prednisone Dexamethasone


61 NSAIDs by mouth or by injection Piroxicam (Feldene®) Deramaxx®
Cancer cells express cyclo-oxygenases that form prostaglandins Prostaglandins of the E2 series inhibit NK cells NK cells kill cancer cells COX-2 inhibitors and other COX inhibitors inhibit formation of the PGE2 series They remove inhibition of NK cells by cancer cells Deramaxx® Previcox®

62 Piroxicam – COX inhibitors
Dose: 0.3 mg/kg PO SID to QOD Little data, but some believe any COX inhibitor is just as good Carprofen (Rimadyl®), meloxicam (Metacam®), Zubrin®, Oncior®, etc. No studies of antineoplastic effects in cats Indications: carcinomas, sarcomas Generally not LSA or MCT because those are on pred Unique Side Effects: Positive side effects – antipyretic, anti-inflammatory, analgesic effects Inhibits platelet aggregation like aspirin

63 Piroxicam – COX inhibitors
Unique Side Effects: GI ulceration Renal papillary necrosis – monitor especially in cats peritonitis Drug Interactions: do not give with corticosteroids or furosemide Displaces protein bound drugs to increase toxicity – aminoglycosides, anticoagulants, sulfas, phenytoin Contraindications: serious toxicity when NSAIDs used with methotrexate

64 Enzymes L-Asparaginase (Elspar®)

65 L-Asparaginase MOA: Dose: 10,000 U/m2 SC, IM, IV (max dose 1 vial)
To make a cancer drug, some fundamental difference between cancer cells and normal cells must be defined and exploited Lymphoproliferative tumors require huge amounts of asparagine to support tumor growth, and lack L-asparaginase synthetase Asparaginase is an enzyme that breaks down asparagine Tumor cells become depleted and rapidly die Dose: 10,000 U/m2 SC, IM, IV (max dose 1 vial) Pretreat with diphenhydramine Indications: Lymphoma, MCT When bone marrow is compromised , bulky disease or ALL Works only 2-3 times in most cases

66 L-Asparaginase Unique Side Effects: Drug Interactions:
IV administration increases risk of anaphylaxis Induction of hepatic encephalitis in patients with liver failure Rare coagulopathy or hepatotoxicity Hyperglycemia and dysregulation in diabetics Thyroid suppression for 4 weeks Drug Interactions: Reduced efficacy of methotrexate (wait 48 hours) Occasional marrow suppression when given with vincristine Contraindications: history of pancreatitis

67 L-Asparaginase Handling:
no special handling is necessary as other chemo drugs Keep refrigerated Once reconstituted, good for 8 hours – 14 days Discard turbid solutions Dilute with D5W or sodium chloride – volume not crucial Avoid shaking vigorously – becomes foamy and difficult to inject

68 Acknowledgements Ruthanne Chun, BS, DVM, DACVIM(Oncology) UW­ Madison School of Vet Med, Madison, WI Plumb Veterinary Drug Handbook, 7th edition

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