1. Practical Oncology Mast Cell Tumor Wendy Blount, DVM

2. Mast Cell Tumor Mast cell granules contain histamine and heparin, among other things Degranulation is largely responsible for symptoms Release of histamine – Increased gastrin secretion (anorexia, ulcers, hematemesis) – Anaphylactoid reaction Release of heparin – less clinically significant

3. Mast Cell Tumor Most often found on the skin – Most common skin tumor in the dog – Brachycephalics & retrievers predisposed 2 nd most common cancer in dogs Also visceral & elsewhere – Gastrointestinal, Spleen, bone marrow Less common sites – Oropharyngeal – Mediastinum – CNS – Nail bed, ocular & periocular

4. Mast Cell Tumor Can have many different appearances Can be infiltrated with fat Symptoms can be waxing and waning Tumor gets bigger and smaller over time 5-15% have multiple masses at presentation 20-50% will have more MCT in the future, even if the first are cured

5. Etiology Allergic skin disease? C-KIT mutation (aka SCFR, CD117) – In “high risk MCT” (high grade II & all grade III) – These have decreased survival time – can be treated with tyrosine kinase inhibitors (Palladia & Kinavet-CA1 ) – SCFR – stem cell factor receptor – C-KIT normally regulates proliferation, migration and differentiation – When C-KIT is mutated, it is constantly turned on, dysregulating cell growth an promoting malignancy

6. Clinical Signs GI Signs – Anorexia, vomiting, melena Pruritus and skin flushing Facial swelling Weakness, lethargy Delayed wound healing Darier’s Sign – swollen, itchy, red skin after scratching or stroking the skin

7. GI Signs – Anorexia, vomiting, melena Pruritus and skin flushing Facial swelling Weakness, lethargy Delayed wound healing Darier’s Sign – swollen, itchy, red skin after scratching or stroking the skin Clinical Signs

8. Staging for Metastasis Eva Gerome Bonham TX Chris Longo – Diamondhead, MS Melanie Enger, - Lufkin TX

9. Diagnosis FNA Cytology often diagnostic – Round cells with or without granules – Granules intracellular or in background – Granules form a halo around the relatively pale nucleus – eosinophils Give diphenhydramine before or right after aspiration – FNA can cause degranulation – Dexamethasone as well if mass is visibly inflamed

10. Diagnosis FNA Cytology often diagnostic – Round cells with or without granules – Granules intracellular or in background – eosinophils Give diphenhydramine before or right after aspiration – FNA can cause degranulation – Dexamethasone as well if mass is visibly inflamed

11. Diagnosis FNA Cytology often diagnostic – Round cells with or without granules – Granules intracellular or in background – eosinophils Give diphenhydramine before or right after aspiration – FNA can cause degranulation – Dexamethasone as well if mass is visibly inflamed

12. Diagnosis FNA Cytology often diagnostic – Round cells with or without granules – Granules intracellular or in background – eosinophils Give diphenhydramine before or right after aspiration – FNA can cause degranulation – Dexamethasone as well if mass is visibly inflamed

13. Diagnosis FNA Cytology often diagnostic – Round cells with or without granules – Granules intracellular or in background – eosinophils Give diphenhydramine before or right after aspiration – FNA can cause degranulation – Dexamethasone as well if mass is visibly inflamed

14. Staging for Metastasis Histopathology for grading – Excisional if resectable – Incisional if not FNA draining lymph node – Clusters of mast cells likely metastasis – Single mast cells likely not Abdominal US with FNA liver and spleen CBC, panel, buffy coat

15. Staging for Metastasis Non-resectable MCT

16. Staging for Metastasis Non-resectable MCT

17. Staging for Metastasis Non-resectable MCT

18. Staging for Metastasis Lymph node cytologies

19. Staging for Metastasis Lymph node cytologies

20. Staging for Metastasis Lymph node cytologies

21. Tumor Stage (WHO) Stage 0 – microscopic disease only Stage I – tumor confined to the dermis Stage II – tumor does not infiltrate subcutaneous tissues, lymph node metastasis Stage III – large, infiltrating tumor or multiple tumors Stage IV – distant metastasis Consideration is being given to reducing stage of multiple dermal tumors

22. Histopathology grade Mitotic Index (MI) Surgical margins – clean, narrow or dirty Invasiveness – dermal or invasive (subcutaneous/muscle) Histopathology tells a great deal about prognosis and treatment indicated

23. Histopathologic Grading Grade I – well differentiated, behaves benignly Grade II – intermediate differentiation, behavior is widely variable – Low grade II – often behaves benignly – High grade II – C-kit mutation, often behaves malignantly – Determined by MSU prognostic panel (form)MSU prognostic panelform Grade III – anaplastic, aggressive behavior This is the Patnaik System Obsolete system has grade I the worst and grade III the best prognosis

24. Surgery Mainstay of low grade MCT treatment Mast Cell Tumors often extend well beyond the visible mass Diagnose by FNA before you excise Lateral margins 2-3 cm beyond visible mass – Small tumors <1 cm, 1.5-2cm margins may be adequate One fascia layer deep to visible mass Avoid manipulating the tumor Intraoperative cytologies on 4 lateral and deep margins can be helpful

25. Surgery Prednisone for pre-surgical cytoreduction Out of favor by oncologists at this time I still like use it – Stabilizes lysosomal membranes – may prevent degranulation caused by surgery – Controls inflammation around the tumor so tumor borders are easier to see – Usually makes the dog feel better, so client perceives better toleration of surgery Prednisone 40 mg/m 2 PO SID x 7days, then QOD

26. Surgery Re-excision where borders are dirty on grade I or II Grade III tumors considered systemic – More surgery only for local palliation 3 cm beyond original surgery One fascia layer deeper than original surgery Complete resection results in long survival If clean borders, 95% cured with second excision, using these rules

27. Surgery NeoAdjuvant Therapy Given to a patient with non-resectable tumor in hopes of making it resectable Chemotherapy and/or radiation Best managed by medical and/or radiation oncologists Need to understand effects of neoadjuvant therapy on healing and when and how to do surgery

28. Sandra Goodwin – Forney TX Sandra Goodwin’s Compadre Betsy Hoffman Robinson – League City TX

29. Chemotherapy Not indicated for multiple dermal MCT that are cured by excision To deal with MCT at the tumor borders when radiation not possible To improve post-surgical prognosis for high risk grade II and all grade III MCT To palliate metastatic or systemic disease Surprisingly, there are few studies to evaluate efficacy of various protocols

30. Chemotherapy Vinblastine and prednisone (VP) Median survival 134 days (5 months) – gross disease after surgery Median survival 1013 days (3 years) – microscopic disease after surgery 45% survival at 2 years Half of these had surgery prior to chemo This has not been my experience with grade III – Most dead in 2-4 months – All gone within the year Vinblastine 2-2.2 mg/m2 IV over 10 min once weekly for 4 weeks, then every other week for 4 doses Prednisone 40 mg/m2 PO SID x 2 weeks then QOD

31. Chemotherapy CCNU 60-70 mg/m2 PO q3-4 weeks – 4 week interval the first time, then shorten if symptoms return during the 4th week – Baseline liver tests (ALT, SAP, albumin) – Pretreat with diphenhydramine Check before 3 rd dose and then prior to each Stop if signs of liver disease to prevent liver failure 6-8 doses common maximum – I have reached 12 at most Grade III median survival 2 months

32. Chemotherapy Alternating VP and CCNU Alternate vinblastine and CCNU every 2 weeks for a total of 8 treatments – Doses on previous slides Prednisone 2 mg/kg PO SID tapered gradually to maintenance dose of 0.5 mg/kg PO SID x 6 months Macroscopic disease grades II and III – 3 remission, 4 PR – median duration of response 58 days 2 patients did not reach 4 th CCNU treatment due to ALT >1000

33. Chemotherapy Vinblastine, prednisone, cyclophosphamide Study on high risk MCT Median progression free interval of more than 2 years Median survival 6 years Grade III and those who needed reduction of vinblastine dose did not do as well New protocol, but this may become a popular protocol in the future

34. Chemotherapy Vincristine alone not effective for MCT COP can work well for grade II MCT Many dirty border grade II do very well with most protocols – many months, years or cured Some grade II with dirty borders spontaneously resolve – Are malignant MCT indistinguishable from inflammatory reaction?

35. Chemotherapy Because of the VP study, most oncologists prefer VP to CCNU or both for grade III My experience is that outcome is similar with all 3 protocols for grade III MCT – Palliative therapy often does just as well – A significant proportion do not respond at all

36. Chemotherapy

37. Chemotherapy Palladia and Kinavet-CA1/Masivet Tyrosine kinase (TKI) inhibitors Prednisone and TKI are the chemo drugs with direct cytotoxicity for MCT – Probably the most effective chemo for high grade MCT Not appropriate for low grade MCT due to toxicity A game changer for high grade very large MCT

38. Chemotherapy Palladia and Kinavet-CA1/Masivet 25% of grade II & III MCT have C-KIT mutation Blocking wild type or mutated KIT causes apoptosis in MCT antiproliferative through KIT blockade antiangiogenic through other MOA

39. Chemotherapy Palladia and Kinavet-CA1/Masivet Indications for use: – Dogs >11-15 lbs only (not cats) – Non-resectable MCT Dirty borders after re-excision – Multiple diffuse or coalescing high grade MCT – Concurrent conditions precluding surgery or multiple sedations for radiation therapy – High grade MCT or C-KIT mutation – Indicated with or without metastasis – Post Chemo – VP x 4 weeks, then Palladia

40. Chemotherapy Palladia and Kinavet-CA1/Masivet Though both are TKIs, there can be resistance to one but not the other – If one fails, try the other – Stable disease is a victory with either Palladia has more broad spectrum activity, and is thought to be more likely to cause clinical response than Kinavet Kinavet response can take up to 2-3 weeks Gleevec is a TKI used in people, but it is very expensive ($100-150 per pill) – Palladia $6-800, Kinavet $500 /month - 70lb dog

41. Chemotherapy Kinavet Administration 12.5 mg/kg PO SID – Dose chart on package insert (Client Info)package insertClient Info – Cannot be used in dogs weighing less than 15 pounds Dose reduction in response to adverse events – stop Kinavet for 1-2 weeks – Reduce dose to 9 mg/kg/day when resumed Weekly CBC/panel for the first 6 weeks – Then every 3 weeks x 2 – Then every 6 weeks thereafter

42. Chemotherapy Palladia Administration 3.25 mg/kg PO QOD (or MWF) – Dose chart on package insertpackage insert – With or without food Dose reduction in response to adverse events – Stop Palladia for 1-2 weeks – 0.5 mg/kg reduction when reduced – Minimum dose 2.2 mg/kg PO QOD Weekly CBC/panel for the first 6 weeks – Then every 3 weeks x 2 – Then every 6 weeks thereafter

43. Chemotherapy Palladia Administration GI side effects common – Make sure owner knows to STOP drug if anorexia, vomiting, diarrhea Dispense Cerenia and metronidazole at the first visit to have on hand Administer H1 and H2 blockers concurrently

44. Chemotherapy Palladia Study – Bergman & Clifford, 2009 Dogs with progressive disease on the blinded phase could enter open-label phase at any time

45. Chemotherapy Palladia Study – Bergman & Clifford, 2009 Statistically significant improvement in objective response rate

46. Chemotherapy Palladia Study – Bergman & Clifford, 2009 57.2% did not respond Among responders, median duration of response was 12 weeks Median time to non-response or death was 18 weeks 82% of dogs with C-KIT mutation responded 54% of dogs without mutation responded There was a placebo response – Likely due to spontaneously resolving degranulation Clin Cancer Res 2009; 15:3856-3865.

47. Chemotherapy Palladia Side effects

48. Chemotherapy Dec. albumin – 13% Palladia, 8% Placebo Palladia given long term leads to glomerular disease and renal failure

49. Chemotherapy Kenneth Kimbrough – Longview TX Stephen Garner – Nacogdoches TX

50. Chemotherapy Kinavet-CA1

51. Chemotherapy

52. Chemotherapy Palliative therapy Prednisone 40 mg/m 2 /day – Wean gradually to 0.5 mg/m 2 /day Antihistamines daily H2 blocker or proton pump blocker – Cimetidine, ranitidine, famotidine – Omeprazole, esomeprazole sucralfate if ulcerated – Hematemesis, melena

53. Radiation Therapy Non-resectable high grade MCT Regional lymph node metastasis Grade II Stage 0 MCT with dirty margins – Disease free interval is increased compared to no treatment – Similar outcome to re-excision if it is possible No indication to irradiate grade II MCT with clean borders

54. Treatments Not Recommended Deionized water injections – At one time recommended for cytoreduction prior to surgery – Subsequent studies have proven ineffective – Risk causing degranulation – Pain on injection intralesional Vetalog or DepoMedrol – Reserved for those dogs who have too many dermal MCT to remove and no evidence of systemic disease

55. Prognosis Stage and grade much more important than with LSA – Grade I with clean borders are cured by surgery – Low grade II clean borders usually cured by surgery – High grade II clean borders should probably have adjunctive chemo or radiation – High grade II with dirty borders should definitely have adjunctive chemo and/or radiation and may have poor prognosis – Virtually all of grade III die of their disease, often within a few months

56. Prognosis Indicators of poor prognosis Dirty borders on re-excision High grade, advanced stage, MI >5 Breed- Shar pei Systemic signs due to degranulation Size and growth rate Location – perineum, scrotum, nail bed, mucocutaneous, muzzle C-kit deletion and other histopath prognostic indicators (MSU/AMC panels)

57. Prognosis Indicators of better prognosis Clean borders on excision Low grade, low stage, MI <5 Breed – Boxers and Pugs

58. Prognosis Indicators of better prognosis Clean borders on excision Low grade, low stage, MI <5 Breed – Boxers and Pugs

59. Prognosis Indicators of better prognosis Clean borders on excision Low grade, low stage, MI <5 Breed – Boxers and Pugs Multiple primary mast cell tumors do not necessarily worsen prognosis Dogs who tend to get one dermal MCT tend to get more, simultaneously or sequentially Warn owners to look for more when you remove the first

60. Prognosis AgNOR staining (MCT prognostic panel)MCT prognostic panel gives more information for grade II Do chemo if high grade II Amputate non-resectable low grade II Cost is about $200 including shipping Send MCT histopath to MSU or AMC, so you can add the prognostic panel if grade II Save center of tumor in formalin to send to MSU /AMC for panel later if grade II Can be difficult to get unstained paraffin sections from the first lab (except TVMDL)

61. Client Handout Mast Cell Tumors Chemo agents discussed Sunday

62. Acknowledgements Philip J. Bergman, DVM, MS, PhD, DACVIM (Oncology) VIN Consultant, CMO BrightHeart Vet Centers Louis-Philippe de Lorimier, DVM, ACVIM (Oncology) VIN Consultant, U of Ill Urbana-Champaign Visiting assistant professor, medical oncology Karri A. Meleo, DVM, ACVIM (Oncology), ACVR VIN Consultant, Vet Onc Serv, Edmonds, WA

63. Acknowledgements Robert C. Rosenthal, DVM, BS, MS, PhD VIN Consultant Kurt R. Verkest, BVSc, BVBiol, MACVSc (Small Animal) VIN Associate Editor, Univ Queensland, Australia Claudia Barton, DVM, ACVIM (Internal Medicine, Oncology) TAMU CVM

64. Acknowledgements Craig Clifford, DVM, MS, ACVIM (Oncology) VIN Consultant