1. Case 6: When the drugs don’t work 2 HSV resistance
Educational Workshops 2015
Case 6: When the drugs don’t work 2 HSV resistance
We are grateful to Manoj Valappil, Honorary Consultant Virologist, Newcastle for composing this case.

2. May 2013 60yr old woman Diagnosed with ALL Chemotherapy - remission
Risk factors for relapse++
Allogeneic BMT
Unrelated donor

3. June 2013 d+16 post BMT Genital ulcer
Q1) What is the Differential diagnosis?

4. Differential diagnosis of genital ulcer
Infectious
HSV
T Pallidum
H Ducreyi
Chlamydia trachomatis serovars L1-3 (lymphogranuloma venereum; LGV)
Klebsiella granulomatis (Granuloma inguinale / “Donovanosis”)
Non-infectious - GvHD, fixed drug reactions, Behçet’s syndrome, neoplasms, and trauma

5. Swab: HSV 2 DNA detected
Was on Aciclovir prophylaxis
Q2) Is this Aciclovir resistance? What is the next step in management?

6. Options: a) Aciclovir resistance unlikely; increase to treatment dose
b) Aciclovir resistance likely; switch to another drug

7. Aciclovir resistance unlikely; switched to iv Aciclovir (treatment dose)
BNF doses given in subsequent slides but higher doses can be given in certain circumstances (if benefit outweighs risk) – up to 15mg/kg IV
The dose needs to be adjusted in renal impairment

8. BNF dosing Genital herpes simplex, treatment of first episode,
200 mg 5 times daily or 400 mg 3 times daily usually for 5 days, longer if new lesions appear during treatment or if healing is incomplete
400 mg 5 times daily for 7–10 days in immunocompromised or HIV-positive patients
Treatment of recurrent infection, 800 mg 3 times daily for 2 days or 200 mg 5 times daily for 5 days or 400 mg 3 times daily for 3–5 days
400 mg 3 times daily for 5–10 days in immunocompromised or HIV-positive patients

9. BNF dosing
Herpes simplex, suppression, 400 mg twice daily or 200 mg 4 times daily; increased to 400 mg 3 times daily if recurrences occur on standard dose
Herpes simplex, prophylaxis in the immunocompromised - 200–400 mg 4 times daily
IV dose - 5 mg/kg every 8 hours usually for 5 days, doubled to 10 mg/kg every 8 hours if resistant organisms suspected
Prophylaxis of herpes simplex in the immunocompromised - 5 mg/kg every 8 hours

10. Q3) When do you suspect HSV antiviral drug resistance?

11. Consider resistance/treatment failure if:
Multiple reactivations/breakthrough
Persistence of lesions >1 week after starting treatment without appreciable response
New satellite lesions few days after adequate therapy

12. Progress Switched to IV Aciclovir 10mg/kg
Ordinarily 5-10 days of treatment
In severely immunocompromised patients, therapy may be extended depending on the clinical response.
Lesions better, discharged home on prophylactic Aciclovir
19/6/13: d+34, acute skin GvHD
Treated with Prednisolone 2mg/kg
EBV reactivation <2x10^3 c/ml

13. July 2013 Perianal ulcer (worse)
HSV2 detected from a swab of the lesion
Possible Aciclovir resistance
Q4) What is the mechanism of action of Aciclovir? What is the mechanism of HSV resistance to Aciclovir?

14. Aciclovir: mechanism of action
Aciclovir is a Guanosine analogue. After three phosphorylation steps it is converted to Guanosine tri-phosphate which is incorporated into the viral DNA and it acts as a DNA chain terminator. Aciclovir is converted to aciclovir monophosphate by the HSV Thymidine kinase. This is then converted into di and tri phosphates by (human) cellular enzymes. Aciclovir tri-phosphate is incorporated into the viral DAN by DNA polymerase. Aciclovir resistance results from mutations in genome coding for Thymidine kinase or DNA polymerase.

15. Aciclovir is a Guanosine analogue
Aciclovir is a Guanosine analogue. After three phosphorylation steps, it is converted into tri-phosphate. Aciclovir is converted to aciclovir monophosphate by the HSV Thymidine kinase. This is then converted into di and tri phosphates by (human) cellular enzymes. Aciclovir tri-phosphate is incorporated into the viral DNA by DNA polymerase. It inhibits replication by acting as a DNA chain terminator. Aciclovir resistance results from mutations in the HSV genome coding for Thymidine kinase or DNA polymerase.

16. Aciclovir resistant HSV
Due to mutations in genes coding for
Thymidine kinase/TK (common)
Variants include:
TK negative
TK reduced
TK altered or
2) DNA Polymerase (rare)

17. Thymidine kinase (UL23) resistance

18. Polymerase (UL30) resistance

19. Q5) What is the prevalence of HSV resistance to Aciclovir?

20. Prevalence of Aciclovir resistant HSV
Immunocompetent %
Immunocompromised
3.5% - 10%
HIV: 3.5-7
SOT:
HSCT:

21. Resistance test was carried out, result:
Genotypic resistance:
deletion of G with a stop codon at position 98
Phenotype:
Antiviral IC50(µM) S/I/R
Aciclovir > Resistant
Penciclovir > Resistant
Foscarnet Sensitive
Cidofovir: testing not available – resistance rare

22. Treatment Started on IV Cidofovir (out patient) Creatinine 74.
Good response to treatment – lesions fully healed
Switched to prophylactic Valaciclovir 1gm bd
Valaciclovir is a pro-drug of aciclovir with better absorption (gives higher plasma levels) but more expensive than Aciclovir

23. Progress EBV reactivation (indicates immunosuppression)
EBV viral load increase >10^6 copies/ml
No clinical evidence of PTLD - treated with Rituximab

24. August 2013 D100 Chimerism 94% (expect 100% around 3 months)
High risk for ALL relapse – ?reduce immunosuppression
High risk for GvHD - ?continue immunosuppression
Balancing act!
Cyclosporine tapered and stopped

25. November 2013
Rash & Diarrhoea
Q6) What is the differential diagnosis?

26. Differential diagnosis
Infection
Inflammatory
GvHD

27. Investigations: Stool: Culture negative
GI virus multiplex PCR panel: negative
Norovirus, Rotavirus, Adenovirus, Sapovirus, Astrovirus
Biopsy: Skin and gut GvHD
IV Methyl prednisolone, ↑Cyclosporin
Improved

28. Progress Recurrence of Genital ulcer – HSV 2 detected
Q7) Will this strain be resistant to aciclovir?

29. Not necessarily
In a new episode of reactivation, virus is likely to be the wild type virus that had originally (at the time of primary infection) established latency in the dorsal root ganglion.

30. Progress Resistance testing: unable to culture
(low ct value 35.8)
Treated with IV Cidofovir (plus Cidofovir gel),
Improved – put back on Valaciclovir prophylaxis
April 2014: Chimerism 100%
Problems with chronic skin GvHD, referred for Extracorporeal photopheresis (ECP)

31. May - August 2014
EBV reactivation - PTLD lesions in the liver and gut. No response to Rituximab (resistant)
Started on chemotherapy for PTLD: CHOP-R
Developed disseminated HSV - Crops of vesicular lesions on the back, sacrum and vulva – spreading to back - break through on Val Acv 1gm bd.
Treated with Foscarnet and discharged on Valacyclovir prophylaxis (1gm tds)

32. October 2014
New lesions
Resistance test: similar result as the first one
Treated with Foscarnet (7 days) and switched to out patient Cidofovir (4 doses over 5 weeks)
Ulcers improved
Repeat swab: HSV not detected

33. January 2015 Deterioration of renal function Cr ↑162, Cr clearance 29
Cidofovir and Foscarnet are nephrotoxic
(also had contrast for CT and gentamicin)
High dose aciclovir and Valaciclovir can crystallise in renal tubules – patients must be well hydrated
Valaciclovir dose decreased to 500mg bd
April 2015: New lesions: HSV detected
Poor renal function – treated with Cidofovir gel (prepared by pharmacy)
Not fully improving

34. May – July 2015 Neutropenic sepsis, Cr 183
Persisting vulval lesions, swab: HSV not detected
?other causes
Biopsy: genital GvHD confirmed
Treated with steroid cream
June 2015: Cr335 (not considered for dialysis)
July 2015: Pneumonia, pseudomonas line infection, E. Coli sepsis , Cr 393
19/7/15: RIP

35. Summary HSV-2 reactivation post HSCT
Despite adequate treatment and prophylaxis, multiple reactivations occurred due to severe immunosuppression for GvHD and PTLD
Aciclovir resistant HSV was treated with second line antiviral agents which were nephrotoxic
Patient eventually developed renal failure
Simultaneous HSV reactivation along with genital GvHD led to a delay in diagnosing genital GvHD in the latter stages

36. Lessons
HSV reactivation is still a problem in immunocompromised patients. Early diagnosis and treatment with high dose acyclovir is critical.
Multiple HSV reactivations can lead to acyclovir resistance.
Persistent/refractory/disseminated acyclovir resistant HSV in immunocompromised patients managed with second line agents are associated with significant morbidity (mortality)
HSV and skin GvHD may co-exist – consider biopsy if lesions are unresponsive to appropriate therapy