Case Two: When the drugs don’t work Drug resistance in CMV Educational Workshops 2015 Case Two: When the drugs don’t work Drug resistance in CMV We are grateful to William Tong, Consultant Virologist, Barts Health NHS Trust, London for composing this case.

Background 35 year old patient with AML Initially diagnosed in 2006 Remission after chemotherapy Relapse of AML August 2012 Mismatched unrelated donor allograft stem cell transplantation

CMV status of donor and recipient Donor CMV IgG negative, recipient CMV IgG positive

What is the significance?

What is the significance? Latent CMV in the recipient Absence of immunity in the donor stem cells against CMV High risk of CMV reactivation

What management strategies are there?

What management strategies are there? Prophylaxis X 3-6 months versus Pre-emptive therapy Monitor CMV viral load. Treat on first sign of reactivation (variable definitions used, copies/ml vs IU/ml) Antiviral agent of choice - Valganciclovir

Monitoring of Plasma viral load Day after transplant CMV viral load (copies/ml) Log value 7 Not detected 11 12 750 2.9 16 780 18 720 21 1508 3.2 25 12022 4.1 27 21730 4.3

How to interpret the CMV viral load result

How to interpret the CMV viral load results Evidence of CMV reactivation from Day 12 If patient is CMV IgG negative pre-transplant, any detectable CMV viral load post-transplant is significant as this indicates a primary infection Significant increase in viral load between Day 21 and Day 25 ~ 1 log increase in viral load within 4 days “Interpret any change in viral load using the log value” Acceptable change within assay = < 0.5 log Significant increase = > 1.0 log

Progress of patient Treated with 2 courses of VGCV (total duration 8 weeks) until CMV viral load undetectable Viral load in blood suppressed, but patient developed diarrhoea

Could CMV be the cause of the diarrhoea?

Could CMV be the cause of the diarrhoea? Colonoscopy with biopsy confirmed two pathologies: CMV colitis and Graft Versus Host Disease (GVHD) A B Typical owl eye inclusion body in colonic biopsy and nuclear staining observed in cytomegalovirus (CMV) colitis. Source: http://www.worldendo.org/news-item-20140301.html Colonic biopsy specimen shows acute graft-vs-host disease, grade III, with crypt destruction and apoptotic cells (A, H&E, x100; B, x400) Source: medscape

Could CMV be the cause of the diarrhoea? Colonoscopy with biopsy confirmed CMV colitis and GVHD Suppressed CMV viral load in plasma does not exclude CMV colitis

Re-started VGCV VGCV re-started but CMV VL continued to increase despite VGCV What to do next?

What to do next? Request CMV resistance test Genotyping method available CMV genes UL97 UL54 Function Protein kinase – phosphorylation of Ganciclovir DNA polymerase – Essential for DNA replication Mutations confer resistance to: Ganciclovir Ganciclovir, Foscarnet, Cidofovir Remain susceptible to: Foscarnet, Cidofovir Cross resistance to other agents acting on the same target

UL97 mutation map UL97 mutations conferring GCV resistance

UL54 mutation map UL54 mutations conferring GCV, CDV and foscarnet resistance

CMV resistance test result UL97 sequencing A594V UL54 no resistance mutation detected Interpretation 7-10 fold resistance to GCV Retains susceptibility to cidofovir and foscarnet

What other options are there?

What other options are there? Immunosuppression reduction Note this patient also has GVHD Foscarnet Cidofovir Newer agents Maribavir Brincidofovir Letermovir

Information for the new agents Maribavir Target UL97 (protein kinase) - Incompatible with ganciclovir Potent in vitro Failed to meet goal in phase III prophylaxis study - no difference cf placebo Available for compassionate use Brincidofovir Prodrug of cidofovir - Conjugated to lipid, released intracellularly Increase oral bioavailability, reduce toxicity Broad spectrum of in vitro antiviral effectiveness Letermovir Terminase (UL56) inhibitor - affects DNA cleavage and packaging Novel target Little toxicity Successful phase II clinical trial in Hematopoietic-Cell Transplantation (N Engl J Med 2014; 370:1781-1789)

Progress Maribavir Cidofovir VGCV VGCV VGCV Log CMV viral load No of days after transplantation

Further progress Readmitted Day 340 after transplant with nausea and diarrhoea Developed SOB requiring O2

Chest X-Ray

What is the diagnosis Differential diagnoses?

What is the diagnosis Presumed CMV pneumonitis Too ill to have bronchoscopy or broncho-aveolar lavage

What treatment is available for CMV pneumonitis?

What treatment is available for CMV pneumonitis? Antiviral + IVIG Note: UK Clinical guidelines for IVIG Outcome poor RIP

Department of Health. Clinical guidelines for immunoglobulin use: second edition 2008 Update to second edition (01 Aug 2011)

Summary A stem cell transplant recipient developed CMV reactivation initially controlled by valganciclovir, but then developed resistance Second line therapies were either intolerant or ineffective Patient eventually died of CMV pneumonitis.

Lessons CMV is still a major cause of mortality and morbidity after transplantation. The use of valganciclovir can prevent or control CMV in most cases, but there is a risk of development of resistance. Current second line therapies against CMV are often suboptimal in effectiveness and can be associated with significant side effects such as renal impairment New antiviral against CMV are badly needed