Nessun titolo diapositiva

1
Mutations in HIV-1 Reverse Transcriptase
Associated with Hypersusceptibility to NNRTI
Impact on Virological Response to Efavirenz-based
Salvage Therapy
V Tozzi, M Zaccarelli, F Ceccherini-Silberstein,
P De Longis, G DOffizi, F Forbici, R DArrigo, E
Boumis, R Bellagamba, S Bonfigli, C Carvelli, P
Narciso, A Antinori and CF Perno. National
Institute for Infectious Diseases "L.
Spallanzani", Via Portuense 292, 00149 Rome,
Italy. Contact e-mail
tozzi_at_inmi.it

• BACKGROUND
• Viral isolates with reduced susceptibility or
  resistance to members of the NRTI class may
  exhibit significant increased susceptibility to
  the NNRTI class of antiretroviral drugs (NNRTI
  hypersusceptibility) (1).
• Hypersusceptibility to NNRTIs can be detected
  in more than 20 of NRTI-experienced patients
  (2).
• Prospective and retrospective clinical trial
  cohort studies have shown that NNRTI
  hypersusceptibility is associated with better
  virological and immunological response to
  efavirenz-based therapy in patients failing
  antiretroviral treatment (3) (4) (5).
• Observational studies may be more
  representative of the real word, since they
  include patients under-represented in clinical
  trials.
• Although the NRTI mutational patterns
  conferring NNRTI hypersusceptibility are not
  clearly defined, mutations at amino acid position
  41, 44, 67, 69, 74, 75, 118, 184, 210, 215, 219
  have been found strongly associated with NNRTI
  hypersusceptibility (2).
• Phenotypic tests are not always available, and
  genotypic tests are often used in many clinical
  sites as unique test to assess drug resistance.
• Studies are needed to increase our
  understanding of the clinical relevance of NRTI
  mutations associated with NNRTI
  hypersusceptibility in routine clinical practice.

RESULTS
Factors related to virological response and to
sustained virological response to treatment At
multivariable analysis, the baseline RT mutations
significantly (plt.05) associated with virological
response among the patients that received
EFV-based regimens were M41L, M184V, L210W,
T215Y, and the association M41L/T215Y and
M41L/T215Y/M184V (Table 4). By contrast, in the
patients that received PI-based regimens only the
M184V mutation was associated with virological
response, while the L210W one was associated with
failure to achieve undetectable viral load (Table
5). A rebound to gt500 copies/m was observed in
27 patients who received EFV-based combination
and in 17 patients who received PI. Mean time to
rebound was 162 days (SD118). No correlation was
found between any mutation and sustained response
to treatment in both groups. Table 4 Probability
of virological response (plasma HIV RNAlt80
copies/ml) and of sustained virological response
(plasma HIV RNAlt80 copies/ml without rebound to
gt500 copies/ml) in patients treated with
EFV-based therapy, according to baseline RT
mutations (multivariable analysis, adjusted by
CD4 cell count, plasma HIV-RNA at GRT, time of
observation and number of HIV-RNA tests
performed). Virological
response Sustained
virological response .
Mutation(s)
Yes No AOR 95CI
p Yes No AOR 95 CI p .
N.() N. () N. ()
N. () N. () M41L 50 (46) 34 (68)
16 (32) 3.023 1.23-7.43 .016 21 (42)
29 (58) 1.789 0.77-4.16 .177 E44D 6 (6)
4 (67) 2 (33) 2.115 0.31-14.2 .442 1
(17) 5 (83) 0.341 0.04-3.16 .344 D67N 36
(33) 23 (64) 13 (36) 2.215
0.87-5.63 .095 11 (31) 25 (69) 0.742
0.30-1.80 .511 T69D 4 (4) 3 (75) 1
(25) 1.872 0.19-18.7 .593 1 (25) 3
(75) 0.472 0.05-4.95 .531 K70R 29 (27) 17
(59) 12 (41) 1.161 0.42-3.18 .772 8 (28) 21
(72) 0.652 0.24-1.76 .397 L74V 1 (1) 0
(0) 1(100) 0.001 0.00-7.6E .752 0 (0)
1(100) 0.001 0.00-7.6E .792 V75I 2 (2)
1 (50) 1 (50) 0.932 0.04-21.3 .965 0 (0)
2 (100) 0.002 0.00-2.8E .797 V118I 30
(28) 21 (70) 9 (30) 2.252 0.82-6.19 .116 15
(50) 15 (50) 1.719 0.69-4.28 .244 Q151M 3
(3) 1 (33) 2 (67) 0.656 0.04-10.7 .766 0
(0) 3 (100) 0.002 0.00-2.4E .758 M184V 73
(67) 48 (66) 25 (34) 3.024 1.31-6.98 .010 31
(43) 42 (57) 1.758 0.76-4.06 .186 L210W 26
(24) 18 (69) 8 (31) 3.312 1.05-10.5 .042
10 (38) 16 (62) 1.291 0.41-3.51 .609 T215Y 47
(43) 33 (70) 14 (30) 3.058 1.26-7.45 .014 19
(40) 28 (60) 1.519 0.66-3.50 .327 K219E 5
(5) 3 (60) 2 (40) 1.677 0.15-19.1 .677 2
(40) 3 (60) 1.969 0.24-16.1 .527 K219Q 16
(15) 9 (56) 7 (44) 1.064 0.28-4.00 .927 5
(31) 11 (69) 0.633 0.17-2.32 .491 M41LT215Y 42
(39) 28 (67) 14 (33) 3.136 1.22-8.10 .018 18
(43) 24 (57) 1.762 0.72-4.29 .212 M41LT215YM1
84V 28 (26) 17 (61) 11 (39) 4.829
1.42-16.4 .012 12 (43) 16 (57) 3.197
0.94-10.9 .064 All patients 109
(100) 69 (63) 40 (37) 42 (39) 67 (61) Table
5 Probability of virological response (plasma HIV
RNAlt80 copies/ml) and of sustained virological
response (plasma HIV RNAlt80 copies/ml without
rebound to gt500 copies/ml) in patients treated
with PI-based therapy, according to baseline RT
mutations (multivariable analysis, adjusted by
CD4 cell count, plasma HIV-RNA at GRT, time of
observation and number of HIV-RNA tests
performed). Virological
response Sustained
virological response .
Mutation(s)
Yes No AOR 95CI
p Yes No AOR 95 CI p
. N.() N. () N. () N. ()
N. () M41L 92 (37) 24 (26) 68 (74)
0.787 0.41-1.51 .468 22 (24) 70
(76) 0.724 0.39-1.36 .313 E44D 25 (10)
6 (24) 19 (76) 0.746 0.23-2.39 .621 6 (24) 19
(76) 0.662 022-1.96 .455 D67N 82 (33)
20 (24) 62 (76) 0.731 0.36-1.49 .390 18 (22)
64 (78) 0.700 0.35-1.38 .303 T69D 19 (8)
4 (21) 15 (79) 0.760 0.18-3.17 .706 4 (21) 15
(79) 0.728 0.19-2.78 .643 K70R 58 (23) 20
(35) 38 (64) 1.220 0.55-2.69 .623 13 (22) 45
(78) 0.773 0.36-1.67 .513 L74V 20 (8) 5
(25) 15 (75) 1.030 0.30-3.50 .962 4 (20 16
(80) 0.711 0.21-2.36 .578 V75I 4 (2) 1
(25) 3 (75) 4.544 0.22-94.0 .327 1 (25) 3
(75) 2.070 0.17-25.1 .568 V118I 40 (16) 11
(28) 29 (73) 0.754 0.32-1.80 .526 7 (18)
33 (82) 1.048 0.89-1.23 .564 Q151M 12 (5)
5 (24) 7 (58) 1.503 0.31-7.12 .607 3 (25)
9 (75) 1.651 0.37-7.34 .510 M184V 127
(62) 53 (42) 74 (58) 2.738 1.48-5.60 .001 42
(33) 85 (67) 1.452 0.82-2.57 .200 L210W 60
(24) 11 (18) 49 (82) 0.424 0.18-0.97 .042 13
(22) 47 (78) 0.673 0.32-1.42 .296 T215Y 85
(34) 23 (27) 62 (73) 0.868 0.54-1.68 .674 21
(25) 64 (75) 0.769 0.41-1.45 .418 K219E 13
(5) 4 (31) 9 (69) 0.952 0.24-3.71 .943 2
(15) 11 (85) 0.411 0.09-1.93 .258 K219Q 43
(17) 14 (33) 29 (67) 0.949 0.39-2.31 .908 9
(21) 34 (79) 0.765 0.32-1.86 .553 M41LT215Y 74
(30) 18 (24) 56 (76) 0.716 0.35-1.46 .359 17
(23) 57 (77) 0.681 0.34-1.36 .275 M41LT215YM18
4V 35 (14) 11 (31) 24 (69) 1.453 0.57-3.68 .431
8 (23) 27 (77) 0.804 0.32-2.03 .643 All
patients 248 (100) 82 (33) 166
(67) 65 (26) 183 (74)
Patients characteristics At baseline the
EFV-treated and the PI-treated patients did not
differ significantly in terms of demography and
HIV disease characteristics (pgt.05 for all
comparisons) (Table 2). All patients that
received EFV-based regimens were NNRTI naive,
while all patients that received PI-based
combinations were PI experienced.
Prevalence of baseline mutations in the RT
gene At baseline the EFV-treated and the
PI-treated patients did not differ significantly
in terms of baseline prevalence of mutations
associated with NRTI resistance (pgt.05 for all
comparisons) (Figure 1).
AIM To examine, in an unselected population of
HIV-infected patients failing antiretroviral
treatment, if NRTI mutations associated with
NNRTI hypersusceptibility are associated with
better virological and immunological response to
efavirenz-based therapy.
Antiretroviral (ARV) treatment ARV treatment was
prescribed by the treating physician as described
in the Methods. Both the EFV-based and the
PI-based regimens contained at least 2 NRTI.
METHODS Study design Retrospective analysis of a
cohort of patients that underwent GRT for HAART
failure followed at a single Clinical Center.
Criteria for selection of the patients All
patients that had GRT between June 1999 and March
2002 were eligible. A total of 470 patients were
screened. 113 patients with previous use of
NNRTIs were excluded. The remaining 357 patients
were evaluated. Clinical and laboratory data were
input in a database for data analyses (Table 1).
Study measures age, gender, HIV transmission
modality, duration of HIV infection, HIV disease
stage, ARV treatment history, CD4 cell counts,
plasma HIV RNA determinations. Genotypic
resistance testing (GRT) and ARV treatment GRT
was performed by Viroseq-2. The ARV treatment was
prescribed by the treating physician after the
GRT results. An expert advice was offered to all
physicians during weekly panel discussions.
Virological and immunological response to
therapy Virological response was defined as
achievement of plasma viral load below 80
copies/ml. Sustained virological response was
defined as achievement of plasma viral load below
80 copies/ml without virological rebound to above
500 copies/ml during the observation period.
Statistical methods The study hypothesis was
that the RT mutations, known from data from the
literature to be associated with
hypersusceptibility to NNRTI, would be
significantly associated with better virological
response to efavirenz-based treatment. Data were
analyzed by the SPSS software statistical
package.
Observation period and follow-up Mean follow-up
was 138 days (standard deviation 181).
Immunological response to treatment We compared
changes in CD4 cell counts between baseline and
last follow-up in patients that received
EFV-based combination. The 35 patients with the
combination of M41L/T215Y/M184V mutations had
gained 93 (206) cells while those without such
mutation combinations had lost 58 (183) CD4
cells (p.042) (Table 3). The remaining
comparisons were not significant.
Table 3 Delta changes (last observation minus
baseline) in CD4 cell count in patients that
after GRT received EFV-based therapy, by RT
mutations at GRT. Mutation(s)
Yes
No . ?
CD4, mean (SD) ? CD4, mean (SD) p .
M41L 95 (177) 16 (230) .059 E44D
173 (242) 46 (206) .151 M184V 78
(181) 4 (252) .089 L210W 110
(191) 34 (213) .111 T215Y 86
(163) 27 (238) .158 M41LT215Y 96
(168) 19 (239) .084 M41LT215YM184V
93 (206) - 58 (183) .042 All patients
53 (209)

• DISCUSSION
• Main findings in the patients treated with
  EFV-based combinations
• 69/109 patients (63.3) achieved undetectable
  (lt80 cp/ml) viral load (by definition all
  patients were NNRTI naive) and 42/109 patients
  (38.5) maintained the virological response
  without rebound to gt500 cp/ml.
• A significant correlation of the baseline
  presence of the M41L, M184V, L210W, and T215Y
  mutations in the RT gene with an increased
  probability of achieving undetectable viral load
  (Table 4).
• Absence of any correlation with the probability
  of maintaining the virological response without
  rebound (Table 4).
• A significant correlation of baseline presence
  of the combination of M41L, M184V, plus T215Y
  mutations with CD4 cells increase (Table 3).
• Main findings in the patients treated with
  PI-based combinations
• Lower rate of virological response (82/248
  33.1) (by definition patients of the PI-group
  were not PI naive).
• Among NRTI mutations associated with NNRTI
  hypersusceptibility only the M184V one was
  associated with increased probability of
  transiently achieving an undetectable viral load
  (reduced viral fitness?), while the remaining
  mutations showed either no correlation or a
  negative one (L210W) (Table 5).
• Differences with previous studies on the topic
• The association of baseline presence of NRTI
  mutations and response to EFV-containing salvage
  regimens  demonstrated, to our knowledge for the
  first time, in a population sample more
  representative of the real world.
• Limits of the study Phenotypic resistance
  testing not performed. Retrospective nature of
  the study.

• CONCLUSIONS
• Our data, obtained in an unselected population
  of HIV-infected patients failing antiretroviral
  treatment and representative of subjects seen in
  routine practice, indicate that some of the RT
  mutations associated with NNRTI
  hypersusceptibility (M41L, M184V, L210W, and
  T215Y) are also associated with better
  virological and immunological response to
  efavirenz-based salvage therapy.
• However the correlation of was seen only with
  the probability of achieving undetectable viral
  load but not with the probability of remaining
  undetectable without virological rebound.
• The latter finding suggests the need of
  additional therapeutic strategies to maintain a
  stable virological response if efavirenz is used
  in this setting.
• The clinical implications of the above
  mentioned benefits on laboratory markers is still
  a matter of debate.

REFERENCES 1) Whitcomb J, Deeks S, Huang W, et
al. 7th Conference on Retroviruses and
Opportunistic Infections. San Francisco,
January-February 2000 (Abstract 234). 2) Whitcomb
JM, Huang W, Limoli K, et al. AIDS 2002 16
41-47. 3) Shulman N, Zolopa AR, Passaro D, et
al. AIDS 2001 15 1125-322. 4) Haubrich RH,
Kemper CA, Hellmann NS, et al. AIDS 2002 16
33-40. 5) Mellors J, Vaida F, Bennett K, et al.
Ninth Conference on Retroviruses and
Opportunistic Infections (Abstact 45).
Table 1. Criteria for patients and data
selection. Study population
Study outcomes
EFV-based combinations (N109)

• Virological response
• Sustained virological response
• Immunological response

• GRT for HAART failure
• No prior NNRTI use

PI-based combinations (N248)