2. To use case-based discussions to answer the
following questions:
When to suspect treatment failure?
Role of HIV resistance assay?
What are the second-line ARV options?
How to promote adherence?
3. effective control of the AIDS pandemicremains
elusive
molecularpathogenesis of human
immunodeficiency virus is at the root of the
problem
HIV has several mechanisms to elude immune
control high mutation rate from RT, CD4 target,
integration into host genome,
The Challenge of HIV-1 Subtype Diversity Barbara S. Taylor,
M.D., Magdalena E. Sobieszczyk, M.D., M.P.H., Francine E.
McCutchan, Ph.D., and Scott M. Hammer, M.D. NEJM 2008;
358:1590-1602
4. RT lacks proofreading activity: mutation rate of
3.4x10–5
mutations per bp per replication cycle
HIV genome 104
base pairs, baseline rate of
replication 1010
virions/day, millions of variants
are produced within any infected person per
day
HIV-1 recombination can lead to further viral
diversity and occurs when one person is
coinfected with two separate strains of the virus
that are multiplying in the same cell
8. 28/M diagnosed with HIV in 2012, CD4 174
cells/mm3 and was started on zidovudine,
nevirapine and lamivudine without any
problems. The patient was lost to followup after
one year of treatment and now returns to your
clinic and has been off meds for three months. He
now wants to go back on ARVs and swears he will
never stop them again.
9. Which approach is the most reasonable in terms
of managing this patients ARVs?
a. check CD4 count before resuming ARVs
b. check viral load before resuming ARVs
c. send a drug resistance assay before resuming
ARVs
d. start the old regimen
e. start a new regimen: tenofovir + lamivudine +
efavirenz
10.
11. a. check CD4 count before resuming ARVs
while it is reasonable to check baseline CD4 at
this time, it is not a requirement for restarting
ARVs
the patient was already on ARVs and thus has the
indication for treatment
Would do this IN ADDITION TO restarting old
regimen
12. b. check viral load before resuming ARVs
Will almost certainly not be suppressed
While ok to do to check baseline, also not a
prerequisite for restarting ARVs
13. c. send a drug resistance assay before resuming
ARVs
Not appropriate to do drug-resistance assay due
to possible reversion of virus to wild-type off
ARVs, therefore resistance may not be detected
Should be done once on old regimen for at least 3
months and VL remains >1,000
14. d. start the old regimen
Correct answer
Restarting old regimen is appropriate since this
was previously tolerated, and will help determine if
drug resistance is present
15. e. start a new regimen: tenofovir + lamivudine +
efavirenz
Inappropriate since there is no resistance data to
guide treatment choices
If already with NNRTI resistance (K103N),
efavirenz will be useless and may end up with
suboptimal therapy
16. 2 types: genotypic and phenotypic
Genotypic resistance uses mutations on HIV
genome to predict resistance to drugs
Good predictive value for NRTIs and NNRTIs
Poor predictive value for protease inhibitors
Phenotypic resistance uses hybrid virus assays,
difficult to do but best for predicting response to
protease inhibitors, or when you need to use a
drug with intermediate resistance on genotyping
17. Uses sequencing of viruses to determine presence of
resistance mutations
Many methods, WHO recommended method is bulk
Sanger sequencing
Many variants are present in a person’s body, Sanger
will detect a mutation if present in at least 10-20% of
virus population
Allele-specific PCR and deep-sequencing next
generation methods can detect archived mutation at
1% of virus population
18.
19.
20. Drug-resistance mutations to HIV usually come at a
cost, in terms of fitness (stability of the virus) or
replicative capacity (how efficiently it can reproduce)
Therefore, lowest energy state is “wild-type” which
mutated viruses revert to in absence of drug pressure
Previous mutation is “archived” but undetectable on
bulk sequencing, but can re-emerge once drug
pressure returns
21. Therefore, all resistance testing for acquired drug
resistance should be done WHILE ON THE OLD
ARV regimen
Otherwise, mutations may not be detected
22. Earliest is non-suppressed viral load
Expect at least one log decrease after 1 month of
ARVs, expect <1,000 copies or suppression in 3
months
Decreasing CD4 count – immunologic failure
Last to happen is clinical progression – OI’s,
wasting etc.
23. The patient’s old regimen of zidovudine +
lamivudine + nevirapine is resumed
After 3 months, viral load is 50,000 copies
A drug resistance genotype is sent with the
following results:
NRTI: M184V (resistant to lamivudine)
NNRTI: K103N (resistant to nevirapine and
efavirenz)
PI: no drug resistance mutations
24. What is the best regimen for this patient?
a. no change until we get another viral load after 3
months
b. shift to tenofovir + zidovudine* + lopinavir-ritonavir
c. shift to tenofovir + zidovudine* + efavirenz because
the efavirenz resistance is spurious since he has never
been exposed to this drug
* (+lamivudine if no standalone zidovudine)
25.
26. a. no change until we get another viral load after 3
months
There is no point in waiting to shift due to the
significant viral load. If this was just a “blip” (<1000
copies), it might be reasonable to continue and
recheck but the viral load in this case is a true
treatment failure for this time frame
27. b. shift to tenofovir + zidovudine (+lamivudine if no
standalone zidovudine) + lopinavir-ritonavir
Shifting to three active drugs is standard of care
for second line ARVs
Retaining lamivudine since zidovudine is co-
formulated with it is fine, and may have some
benefit since M184V confers hypersusceptibility to
zidovudine
28. c. shift to tenofovir + zidovudine (+lamivudine if no
standalone zidovudine) + efavirenz because the
efavirenz resistance is spurious since he has
never been exposed to this drug
K103N confers multiple high level NNRTI
resistance with the exception of etravirine (not
available) so efavirenz should NOT be used
NNRTI resistance is fairly common due to low
barrier to resistance
29. Take home points:
Resistance testing should be done with the
original regimen onboard to ensure that the
resistance mutations can be detected
Always make sure there are 3 active drugs: 2
NNRTIs plus either an active NNRTI or PI
30. 35/M diagnosed with HIV in 2013 with CD4 count
of 287 cells/mm3, co-infected with hepatitis B,
started on tenofovir + lamivudine + efavirenz 6
months ago. Repeat CD4 count is 198 cells/mm3
and subsequent viral load shows 20,000 copies.
On further questioning, he recalls that he was
given entecavir by a doctor in 2008 for one year,
but he stopped it due to cost.
31. At this point, the correct course of action is to:
a. stop treatment and send a genotype
b. continue treatment and send a genotype
c. add entecavir to his regimen and send another
viral load in 3 months
32.
33. a. stop treatment and send a genotype
There is no reason to stop treatment at this time
because doing so can potentially lead to more
resistance mutations
Efavirenz in particular has a longer half life than
tenofovir or lamivudine and stopping all meds can
lead to a period of virtual efavirenz monotherapy
Continued drug pressure also makes the virus
less fit
34. b. continue treatment and send a genotype
Treatment with the current regimen should be
continued while awaiting the genotype
Once genotype is back, ARVs can be adjusted
depending on resistance pattern
35. c. add entecavir to his regimen and send another
viral load in 3 months
There is no reason to add another hepatitis B-
active drug in this patient who is already on
temofovir and lamivudine
In fact, the entecavir may have induced resistance
to lamivudine (M184) since HIV virus was
probably around back in 2008 and received
monotherapy with entecavir which induces cross-
resistance with lamivudine
36. Drug resistance genotype returns with the
following results:
NRTI: M184V (resistant to lamivudine)
NNRTI: no drug resistance mutations
PI: no drug resistance mutations
37. Aside from continuing tenofovir + zidovudine*,
what is the best additional drug for this patient?
a. nevirapine because efavirenz is compromised
b. lopinavir-ritonavir because efavirenz is
compromised
c. maintain efavirenz
*(+lamivudine if no standalone zidovudine)
38.
39. a. nevirapine because efavirenz is compromised
No reason to switch from efavirenz to nevirapine
since there is no evidence of resistance to
efavirenz
40. b. lopinavir-ritonavir because efavirenz is
compromised
No reason to switch efavirenz to a PI since no
evidence of resistance
41. c. maintain efavirenz
Best regimen available for this patient
Take home message is to test patients for HIV
before starting lamivudine, clevudine, tenofovir or
entecavir for HBV
42. Simpler regimens – new one pill a day
(TDF+3TC+EFV)
Pill boxes help if with multiple meds
Recurring reminders (alarm, text etc.)
Once a day regimens (give PI + lamivudine +
tenofovir all at the same time*)
Medication buddy/ relative to remind patient of
meds and appointments
Reinforcement, pill counts at each visit
Explain that this is his/her life
43. Red top with 10 cc of blood
Can submit up to 8 hours after draw as long as it
is kept on ice or refrigerated
P4,500 at UP-NIH
Request form being developed, likely will include
ARV history and some clinical parameters
Please coordinate specimen drop with us: call
PGH treatment hub 5548400 loc 3249
44.
45.
46. 84% CRF01_AE, 13% B
Showed drug treatment failure rate at 1 year of
antiretrovirals of 10.3%
Showed concerning trend in tenofovir resistance
Suggested possible transmitted drug resistance
Showed that 57% of treatment failures without
effective second-line
47. High rate of treatment failure with tenofovir-based
regimens
Worst regimen: TDF+3TC+NVP (29%)
Most durable: AZT+3TC+EFV (3.9%)
1st
line: TDF+3TC+EFV (12.6%)
May need to revisit WHO guidelines for non-B
subtypes (distribution of failures: CRF01_AE 87%,
B 11% and C 2%)
48.
49.
50. 95 patients enrolled from PGH
San Lazaro IRB presented and preliminary
approval, awaiting MOA review to start
51. 88/95 participants are males, all MSMs
7 women, 3 pregnant
Median age 30 years
Median CD4 90 cells/mm3
Median VL 179,200
18 with HBV, denies any NRTI use
52. CRF01_AE=78 (82%),
B=9 (9.5%)
CRF01_AE/B=4
CRF01_AE/F1/B=2
CRF02_AG= 1
CRF01_AE/CRF15_01B=1
May have found one new subtype (still processing)
Four may be recombinants between CRF01_AE
and B – NGS pending to confirm
53. 6 samples had baseline clinically significant
mutations for a partial transmitted drug prevalence
of 6.3% out of 95 sequenced samples.
NNRTI resistance is 4.2%, NRTI is 2.1%
All were CRF01_AE subtype. Five samples had
one mutation each and one sample had two
mutations
54.
55. Resistance to ARVs is emerging
Know clues to resistance, and order genotype
testing appropriately including continuing old
regimen before testing
Previous hepatitis B treatment is a clue to possible
pre-existing resistance, genotyping may be
appropriate at baseline
When in doubt, consult colleagues
We need more treatment options
