A Review of Selected Presentations From the 2018 BMT Tandem Meetings
• February 21-25, 2018 • Salt Lake City, Utah
Letermovir Resistance Genotyping in a Clinical Trial of Cytomegalovirus Prophylaxis for Hematopoietic Cell Transplant Recipients
Most adults who undergo hematopoietic stem cell transplant (HSCT) have evidence of prior infection with cytomegalovirus (CMV) and are at risk for CMV reactivation after transplant. In November 2017, letermovir was approved by the US Food and Drug Administration (FDA) for the prophylaxis of CMV infection and disease in adult CMV-seropositive recipients of an allogeneic HSCT.1 Letermovir is an antiviral compound with a novel mechanism of action: It targets the CMV DNA terminase complex, which is required for viral DNA processing and the assembly of infectious virions. With a median EC50 of 2.1 nM against clinical CMV isolates, letermovir is a potent inhibitor of CMV. Moreover, letermovir has demonstrated activity against CMV strains that are resistant to DNA polymerase inhibitors, such as cidofovir and ganciclovir. The CMV terminase complex consists of 2 protein subunits, pUL89 and pUL56.2 The function of the terminase complex is to cleave CMV DNA concatemers into single units prior to packaging in the capsid. DNA sequencing revealed mutations in the UL56 gene among mutant CMV variants that were resistant to letermovir in vitro. Although UL56 mutations that confer resistance to letermovir have occasionally been observed in the clinic, the most common UL56 polymorphisms do not affect susceptibility to letermovir.
Letermovir was evaluated in the phase 3 MK-8228-001 study (P001; Letermovir [MK-8228] Versus Placebo in the Prevention of Clinically-Significant Cytomegalovirus [CMV] Infection in Adult, CMV-Seropositive Allogeneic Hematopoietic Stem Cell Transplant Recipients) of CMV-seropositive patients who underwent allogeneic HSCT.3,4 The double-blind study randomly assigned 565 patients in 20 countries in a 2:1 ratio to receive letermovir at 480 mg or placebo. The letermovir dose was reduced to 240 mg in patients receiving cyclosporine. The study medication was initiated within 28 days after transplant and continued through week 14. Preemptive therapy was administered to patients who exhibited clinically significant CMV infection. CMV genotyping was assessed by next-generation sequencing.
Among the 495 patients in the primary efficacy population, 128 developed clinically significant CMV infection during the first 24 weeks after HSCT. The study randomly assigned 57 patients to the letermovir arm and 71 patients to the placebo arm. CMV DNA samples for sequencing were available for 34 patients in the letermovir arm and 50 patients in the placebo arm. To increase the number of samples available for genotyping, plasma samples that had been collected for viral load testing were repurposed and analyzed for CMV genotyping. This step increased the number of samples available for genotyping to 40 in the letermovir arm and 42 in the placebo arm. Plasma samples were drawn only from patients who experienced clinically significant CMV infection. Baseline plasma samples were not collected from any of the patients.
Next-generation sequ-en-cing is extremely sensitive, but the results can be confounded by polymerase chain reaction (PCR) artifacts resulting from the presence of very low numbers of the starting template. In the P001 trial, the median viral load at failure was approximately 400 copies/mL in the letermovir arm vs 700 copies/mL in the placebo arm. Two strategies were used to reduce sequencing artifacts. First, to be considered a true variant, the sequence had to be present in at least 5% of the sample sequence data. Second, replicate testing was used to detect true variants. Replicate testing was performed on samples with novel substitutions that were present in 5% to 98% of sequence reads at a single nucleotide position. The protocol for replicate testing was to repeat the DNA isolation, amplification, and sequencing for the sample in question. If any of the replicate tests confirmed the original mutation, then the mutation was considered correct. Among the 21 substitutions evaluated by replicate testing, 13 were in the UL89 gene and 8 were in the UL56 gene. Eighteen of these samples failed replicate testing and were therefore considered sequencing artifacts. Numerous known UL56 variants were identified (Table 1). The analysis also identified common variants that had not been characterized for letermovir resistance, many of which were observed among patients in the placebo arm. These common variants were unlikely to have emerged under selection pressure associated with letermovir. They included R246C (n=1), N446S (n=7), SNS445-447 deletion (n=3), S484G (n=1), and A779V (n=4).
Another group included 14 novel variants that had not been characterized for letermovir resistance. Most identified mutations occurred in 2 known variable regions (VR1 and VR2) of the UL56 gene and were therefore unlikely to have evolved from selection pressure associated with letermovir. Variant V236M was identified in this group. The change from valine to methionine was associated with a reduction in letermovir affinity for CMV, as represented by a 30- to 50-fold increase in the EC50 in a cell-culture model of CMV infection. However, the mutation did not affect the affinity of other antiviral agents, including cidofovir, foscarnet, and ganciclovir.5 The V236M mutation was not observed in any of the patients in the placebo arm of trial P001, nor was it observed among CMV pUL56 sequences in public databases. One patient in a phase 2b trial of letermovir (60 mg daily) had the CMV V236M mutation (Figure 1).6 Both this patient and the patient with the CMV V236M mutation in the P001 trial were successfully treated with ganciclovir or valganciclovir preemptive therapy.
In the phase 3 trial, all-cause mortality was 20.9% in the letermovir arm vs 25.5% in the placebo arm at week 48 after transplant.4 The frequency and severity of adverse events were similar in the letermovir and placebo groups. Most adverse events were of low grade. Vomiting was reported in 18.5% of the patients in the letermovir arm vs 13.5% in the placebo arm. Edema was observed in 14.5% vs 9.4%, respectively, and atrial fibrillation or flutter occurred in 4.6% vs 1.0%. Rates of myelotoxicity and nephrotoxicity were similar in the 2 groups.
References
1. PREVYMIS (letermovir) tablets and PREVYMIS (letermovir) injection. US Food and Drug Administration. https://www.accessdata.fda.gov/drugsatfda_docs/nda/2017/209939Orig1s000,209940Orig1s000TOC.cfm. Posted December 18, 2017. Accessed March 28, 2018.
2. Melendez DP, Razonable RR. Letermovir and inhibitors of the terminase complex: a promising new class of investigational antiviral drugs against human cytomegalovirus. Infect Drug Resist. 2015;8:269-277.
3. Douglas CM, Levitan D, Maguire M, et al. Letermovir resistance genotyping in a clinical trial of cytomegalovirus prophylaxis for hematopoietic cell transplant recipients [BMT Tandem Meetings abstract 72]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
4. Marty FM, Ljungman P, Chemaly RF, et al. Letermovir prophylaxis for cytomegalovirus in hematopoietic-cell transplantation. N Engl J Med. 2017;377(25):2433-2444.
5. Piret J, Goyette N, Boivin G. Drug susceptibility and replicative capacity of multidrug-resistant recombinant human cytomegalovirus harboring mutations in UL56 and UL54 genes. Antimicrob Agents Chemother. 2017;61(11):e01044-17.
6. Lischka P, Michel D, Zimmermann H. Characterization of cytomegalovirus breakthrough events in a phase 2 prophylaxis trial of letermovir (AIC246, MK 8228). J Infect Dis. 2016;213(1):23-30.
Viral Kinetic Correlates of Cytomegalovirus Disease and Death After Hematopoietic Cell Transplant
Preemptive treatment of CMV with ganciclovir and foscarnet has been the standard of care for nearly 20 years.1 The development of preemptive therapy in response to PCR-based detection of viral DNA has led to a low incidence of CMV after HSCT, with rates of 3% to 5% in the first 100 days after the procedure.2,3 Toxicities associated with standard preemptive therapy remain high. However, the low rates of CMV infection have made it more challenging to develop new antiviral agents. Although detection of CMV DNA is commonly used as the clinical finding that signals the need for preemptive therapy, it has not been established as a surrogate endpoint for clinically significant CMV disease in a randomized, placebo-controlled clinical trial.
The safety and efficacy of ganciclovir as preemptive treatment for CMV were assessed in a randomized, placebo-controlled, phase 3 trial. This study also extended the data from an early landmark trial to establish the long-term impact of early treatment for CMV.4 In addition, the trial established virologic, kinetic, PCR-based correlates of the risk for CMV disease and death after HSCT, with the goal of establishing surrogate endpoints defined by viral load. A double-blind study published in 1991 established the value of early treatment of CMV infection in reducing the incidence of CMV disease and improving survival after allogeneic bone marrow transplant.5 This study evaluated 72 bone marrow transplant recipients who were seropositive for CMV based on viral culture. After transplant, surveillance cultures of the blood, urine, and throat were performed weekly on all patients. CMV disease developed in 3% of patients treated with prophylactic ganciclovir vs 43% of patients in the placebo arm (P<.00001). By day 100 after transplant, 6 patients in the placebo group had died (all from CMV-related complications), and 1 patient in the ganciclovir group had died (from leukemic relapse). The difference in overall survival was significant at 100 days (P=.04) and 180 days (P=.03) after HSCT.
Frozen plasma samples for the 72 patients in the trial were used in the current study.4 The new analysis included retrospective specimen testing, reanalysis of the existing data, and extension of the chart review. Viral kinetic calculations were performed, and correlations were evaluated by means of the Cox proportional hazards model. Mathematical extension of the results to 3 years showed a significant reduction in CMV disease (P=.02) and improvement in overall survival (P=.04), even though ganciclovir had been administered only through day 100 after HSCT. Extension of the results to 20 years continued to show a reduced incidence of CMV disease among patients treated with preemptive ganciclovir (P=.01). Differences in overall survival data were significant through 3 years (P=.04; Figure 2), and the survival curves remained well-separated through year 20.
The concept of using viral load as a surrogate endpoint was established in the field of AIDS research. In 1997, the FDA accepted viral load as an endpoint for disease-related mortality in trials of AIDS and HIV. Several criteria must be met to establish a surrogate endpoint, including use in a randomized controlled trial that demonstrated effective intervention and incorporated measurement of a biomarker, along with other clinical endpoints. The biomarker must reflect the effect of the intervention on the clinical endpoint.
For the 72 patients from the 1991 study, superimposition of plots reflecting viral load showed a visible reduction in viral load after randomization and administration of ganciclovir, but not placebo. The CMV viral load diverged in the ganciclovir and placebo arms at approximately 6 to 8 weeks after HSCT and immediately after randomization.
Viral kinetic parameters were calculated from CMV DNA PCR values as continuous, time-dependent variables. Cox proportional hazard models were used to assess associations between viral kinetic markers and time to CMV disease or death. Models were adjusted for the presence of acute graft-versus-host disease and donor CMV serostatus. Events were counted through day 100 or day 180. With events counted through day 100 after transplant, variables associated with CMV disease included most recent viral load (P<.001), highest viral load (P<.001), and duration of viremia (P=.01). The same variables were significantly associated with CMV disease or death. With events counted through day 180 after transplant, variables associated with CMV disease included most recent viral load (P<.001), highest viral load (P<.001), and duration of viremia (P=.004), and the same variables were significantly associated with CMV disease or death.
The study authors concluded that 3 markers—viral load, highest viral load, and duration of viremia—warrant further investigation as surrogate endpoints for the relevant clinical endpoints. CMV viral load kinetics correlated with the risk for CMV disease and mortality. However, to establish viral load as a valid surrogate endpoint, further work must show whether the biomarker captures the entire effect of treatment. The option to use viral load as a surrogate endpoint for CMV disease and/or mortality would be of value in optimizing clinical trial design, speeding evaluation of new antiviral agents, and informing clinical management of CMV after bone marrow transplant.
References
1. Tomblyn M, Chiller T, Einsele H, et al; Center for International Blood and Marrow Research; National Marrow Donor program; European Blood and Marrow Transplant Group; American Society of Blood and Marrow Transplantation; Canadian Blood and Marrow Transplant Group; Infectious Diseases Society of America; Society for Healthcare Epidemiology of America; Association of Medical Microbiology and Infectious Disease Canada; Centers for Disease Control and Prevention. Guidelines for preventing infectious complications among hematopoietic cell transplantation recipients: a global perspective. Biol Blood Marrow Transplant. 2009;15(10):1143-1238.
2. Green ML, Leisenring W, Stachel D, et al. Efficacy of a viral load-based, risk-adapted, preemptive treatment strategy for prevention of cytomegalovirus disease after hematopoietic cell transplantation. Biol Blood Marrow Transplant. 2012;18(11):1687-1699.
3. Marty FM, Ljungman P, Chemaly RF, et al. Letermovir prophylaxis for cytomegalovirus in hematopoietic-cell transplantation. N Engl J Med. 2017;377(25):2433-2444.
4. Duke ER, Gilbert PB, Stevens-Ayers TL, et al. Viral kinetic correlates of cytomegalovirus disease and death after hematopoietic cell transplant [BMT Tandem Meetings abstract 1]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
5. Goodrich JM, Mori M, Gleaves CA, et al. Early treatment with ganciclovir to prevent cytomegalovirus disease after allogeneic bone marrow transplantation. N Engl J Med. 1991;325(23):1601-1607.
Cost Effectiveness of Letermovir in Prevention of Clinically Significant CMV Infection in CMV Seropositive Allogeneic Hematopoietic Stem Cell Transplant Recipients
HSCT is associated with a high risk for CMV infection. The phase 3 MK-8228-001/P001 study demonstrated the efficacy of prophylactic letermovir in adult CMV-seropositive patients undergoing allogeneic HSCT.1 The trial showed a significant reduction in the risk for clinically significant CMV infection at 24 weeks posttransplant in patients treated with letermovir vs placebo (18.9% vs 44.3%; P=.0005). The trial also showed a significant reduction in all-cause mortality with letermovir at 24 weeks posttransplant (10.2% vs 15.9%; P=.0327), thus meeting the primary endpoint. Using patient data from the MK-8228-001 trial, a retrospective study evaluated the cost-effectiveness of letermovir vs preemptive treatment from the perspective of a third-party payer. In the MK-8228-001 study, patients were randomly assigned 2:1 to receive letermovir or placebo.2 The total cost of treatment, including letermovir, and lifetime quality-adjusted life years (QALYs) were estimated by a decision-analytic model. Outcomes with letermovir treatment were compared with those in the placebo arm, in which patients received preemptive treatment based on each institution’s standard of care. Efficacy data from the MK-8228-001 clinical trial were available through 24 weeks after transplant and included rates of CMV infection, CMV disease, rehospitalization, mortality, and quality of life. Cost information was obtained from published literature. Life-years during the first 24 weeks were estimated from the clinical trial mortality data. To estimate life-years 24 weeks after transplant, a relative risk for death from HSCT was applied to the general mortality risk calculated from US life expectancy data. Sensitivity analysis explored the impact of including data from the extended follow-up period through 48 weeks posttransplant. The model used an annual discount rate of 3% for costs and benefits. To calculate quality of life, responses from the EQ-5D questionnaire administered in the MK-8228-001 clinical trial were translated into utility values using a time trade-off value set from a population in the United Kingdom.
The base-case analysis showed that the use of letermovir would be cost-effective compared with no use if the incremental cost-effectiveness ratio threshold was at or below $50,000 per QALY gained. Sensitivity analysis incorporating data from 48 weeks posttransplant did not significantly impact the results. The analysis showed that HSCT patients who received treatment with letermovir could be expected to have a prolonged life, with improved health-related quality of life and fewer adverse outcomes (Figure 3). Cost-effectiveness analysis showed that each life-year gained with letermovir treatment had an associated cost of $23,270, and each QALY gained had an associated cost of $25,222. Although the use of letermovir as prophylaxis is associated with an increase in treatment cost relative to the standard of care, the letermovir costs are partially offset by decreases in costs associated with preemptive therapy, CMV-related rehospitalization, CMV disease, and graft-versus-host disease (Figure 4). In probabilistic sensitivity analysis, the majority of incremental cost-effectiveness ratios fell below the willingness-to-pay threshold of $50,000 per QALY gained. The model inputs with the greatest impact were a reduction in the rates of mortality and rehospitalization, and the increased cost of letermovir treatment. The analysis is limited by the paucity of cost data for CMV treatment. In addition, many costs of treatment for CMV infection, disease, and mortality are not routinely captured.
References
1. Douglas CM, Levitan D, Maguire M, et al. Letermovir resistance genotyping in a clinical trial of cytomegalovirus prophylaxis for hematopoietic cell transplant recipients [BMT Tandem Meetings abstract 72]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
2. Schelfhout J, Jiang Y, Miles L, Merchant S, Graham J. Cost effectiveness of letermovir in prevention of clinically significant CMV infection in CMV seropositive allogeneic hematopoietic stem cell transplant recipients [BMT Tandem Meetings abstract 557]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
A Modified Intensive Strategy to Prevent CMV Disease in Seropositive Umbilical Cord Blood Transplant Recipients
Umbilical cord blood transplant is associated with a nearly universal risk of CMV reactivation.1,2 The procedure also confers a risk for CMV disease of up to 28% and an attributable mortality of up to 11% by 1 year posttransplant. Early cord transplant procedures used prophylactic anti-CMV regimens that had been developed for other types of transplant. The standard treatment consists of acyclovir (800 mg twice daily) or valacyclovir (500 mg twice daily). With this regimen, weekly PCR tests are administered to assess viral load, and treatment is initiated at 125 IU/mL. An alternative to standard treatment is an intensive regimen consisting of ganciclovir (5 mg/kg daily) on days –8 through –2 prior to transplant, plus valacyclovir (2 g 3 times daily) after transplant. With this regimen, CMV viral loads are assessed twice weekly, and preemptive therapy is implemented after any positive test. In a comparison of the treatments, the intensive regimen decreased the incidence of CMV disease by 4.7% at 1 year posttransplant, and it was associated with no CMV-related mortality.2
A study conducted at a single institution evaluated the intensive prophylactic treatment vs a modified intensive prophylactic treatment in patients who underwent umbilical cord transplant.3 Data from a separate study of standard prophylactic treatment at the same institution were used for comparison.2 The modified intensive treatment regimen omitted the administration of ganciclovir prior to cord transplant, partly to reduce costs and associated toxicities, but also to address the logistical barrier of treating patients who are not yet hospitalized. The study evaluated the risk for CMV reactivation, rate of CMV disease, and duration of anti-CMV therapy by day 100 posttransplant.
Data were available for 43 patients treated with the intensive regimen from 2008 to 2010. The modified-intensive regimen was used in 40 consecutive CMV-seropositive patients from 2014 to 2017. In the intensive-treatment cohort, fewer patients had received myeloablative conditioning (79% vs 98%), and the median total nucleated cell dose was lower (4.9 × 107/kg vs 7.2 × 107/kg). Both the intensive and modified-intensive regimens showed a significantly reduced incidence of CMV infection compared with the historical data for the standard treatment (P<.001; Figure 5). Moreover, the incidence of CMV infection was similar for the intensive and modified-intensive prophylactic regimens after approximately 60 days posttransplant. Compared with intensive treatment, the modified-intensive regimen had a similar reduction in CMV reactivation (hazard ratio, 1.1; 95% CI, 0.6-1.9; P=.77) and early reactivation (hazard ratio, 1.1; 95% CI, 0.6-2.2; P=.76). The median duration of CMV detection within 100 days posttransplant was 17 days (range, 8-29 days) with intensive treatment vs 36 days (range, 26-47 days) with modified-intensive treatment, representing a mean difference of 9 more days for the modified regimen (range, 0.2-18 days; P=.05). The duration of CMV therapy was also longer in the modified-intensive treatment cohort (mean difference, 9 days [range, –3 to 21 days]; P=.15). However, inclusion of the 7 days of ganciclovir administration in the intensive treatment cohort eliminated this difference.
The median time to engraftment was slightly longer for the patients who received ganciclovir prior to cord blood transplant (20 days vs 17 days). The reduced time to engraftment among patients who received the modified treatment may reflect the fact that these patients also received a higher median dose of nucleated cells (7.2 × 107/kg vs 4.9 × 107/kg). Rates of neutropenia were similar in both cohorts. The rate of acute kidney injury was higher in the intensive therapy cohort (26% vs 4%), whereas the rates of foscarnet use were similar (40% vs 49%, respectively). The modified-intensive regimen was significantly associated with an increase in the proportion of days that patients were alive and not hospitalized.
In summary, outcomes in patients treated with the modified-intensive anti-CMV regimen, which excluded pretransplant ganciclovir, were generally similar to those in patients who received the intensive regimen. Further studies are needed to establish whether pretransplant ganciclovir can be eliminated from prophylactic anti-CMV treatment without a loss of efficacy.
References
1. Dahi PB, Perales MA, Devlin SM, et al. Incidence, nature and mortality of cytomegalovirus infection after double-unit cord blood transplant. Leuk Lymphoma. 2015;56(6):1799-1805.
2. Milano F, Pergam SA, Xie H, et al. Intensive strategy to prevent CMV disease in seropositive umbilical cord blood transplant recipients. Blood. 2011;118(20):5689-5696.
3. Hill JA, Pergam SA, Cox E, et al. A modified intensive strategy to prevent CMV disease in seropositive umbilical cord blood transplant recipients [BMT Tandem Meetings abstract 96]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
Functional Signatures Revealed by Deep Phenotyping of CMV-Specific CD8+ T Cells Predict Risk of Early CMV Reactivation After Allogeneic Hematopoietic Cell Transplantation
CMV reactivation occurs in most seropositive patients after HSCT and is associated with transplant-related mortality, as well as considerable treatment costs.1-3 However, the pivotal phase 3 trial of letermovir vs placebo showed that 39% of patients did not need anti-CMV prophylaxis.4 Therefore, many patients are needlessly receiving preemptive treatment. CMV reactivation after HSCT is controlled by T cells.5 The most immunodominant antigens that CMV-directed T cells recognize include IE1, IE2, and pp65.
In an effort to derive biomarker signatures that might predict the risk for CMV reactivation, CD8-positive T-cell responses to IE1 and pp65 were evaluated in cryopreserved peripheral blood mononuclear cells collected on day 30 after HSCT.6 Samples were categorized into 3 clinically distinct subgroups. Elite controllers (n=19) were CMV-seropositive but never experienced CMV reactivation (based on weekly surveillance testing). Spontaneous controllers (n=16) were CMV-seropositive patients in whom low-grade viremia resolved without antiviral therapy. Noncontrollers (n=21) were CMV-seropositive patients who experienced high-grade CMV viremia (defined as a viral load >1000 IU/mL) and required antiviral therapy. The study’s hypothesis was that the 3 clinically distinct groups of patients would exhibit immunologically distinct cytokine signature profiles within the population of CMV-specific CD8-positive cells.
In comparison with the noncontrollers, spontaneous controllers demonstrated a significantly higher median absolute lymphocyte count, higher numbers of CMV-responsive CD4-positive T cells, and higher numbers of CMV-responsive CD8-positive T cells. The level of CMV-responsive CD4-positive T cells was significantly higher in the elite controllers vs the noncontrollers. Six patients did not respond to therapy. These patients had a significantly lower median absolute lymphocyte count, as well as reduced median levels of CMV-responsive CD4-positive and CD8-positive T cells compared with the cohort of noncontrollers. Interferon γ (IFN-γ) levels alone were not associated with the cumulative incidence of CMV viremia requiring therapy. CMV viremia that required therapy was reported in 31% of patients with high IFN-γ levels vs 21% of those with low levels, a nonsignificant difference.
Functional signatures were shown to correlate with response (Figure 6). The study identified 2 CMV-specific, CD8-positive T-cell cytokine signatures measured at day 30 posttransplant. The CD8-positive T-cell nonprotective signature (interleukin 2 [IL-2]neg, IFN-γpos, tumor necrosis factor α [TNF-α]neg, and macrophage inflammatory protein 1β [MIP-1β]pos) was positively associated with CMV reactivation. CD8-positive T cells with the nonprotective signature were present at higher levels in the combined cohort of spontaneous controllers and noncontrollers compared with the elite controllers (19.4% vs 4.9%; P=.002). Cells with the nonprotective signature were more common in the separate cohorts of spontaneous controllers and noncontrollers compared with the elite controllers. Similar trends were observed for cells stimulated with IE1 or pp65.
Cells with the protective signature produced all 4 cytokines (IL-2pos, IFN-γpos, TNF-αpos, and MIP-1βpos). After stimulation with IE1 or pp65, the proportion of CD8-positive cells with the protective signature was lower among noncontrollers compared with the spontaneous controllers, but the difference did not reach statistical significance. In a multivariate analysis, the presence of the nonprotective cytokine signature was associated with CMV reactivation (P=.02). Patients with more than 5.7% of cells with the nonprotective signature were significantly more likely to experience CMV reactivation compared with patients who had a lower level of cells with the nonprotective signature (71% vs 11%; P=.006). Similarly, using a cutoff value of 16%, patients with a higher level of CD8-positive cells with the nonprotective signature were more likely to experience CMV viremia requiring therapy compared with patients who had lower levels of CD8-positive cells with the nonprotective signature (35% vs 5%; P=.02).
Limitations of the study included the small numbers of patients in each cohort, and the lack of samples available prior to 30 days posttransplant. The mechanisms underlying the associations between CMV status and cytokine signatures remain to be elucidated.
References
1. Green ML, Leisenring W, Xie H, et al. Cytomegalovirus viral load and mortality after haemopoietic stem cell transplantation in the era of pre-emptive therapy: a retrospective cohort study. Lancet Haematol. 2016;3(3):e119-e127.
2. Jain NA, Lu K, Ito S, et al. The clinical and financial burden of pre-emptive management of cytomegalovirus disease after allogeneic stem cell transplantation—implications for preventative treatment approaches. Cytotherapy. 2014;16(7):927-933.
3. Teira P, Battiwalla M, Ramanathan M, et al. Early cytomegalovirus reactivation remains associated with increased transplant-related mortality in the current era: a CIBMTR analysis. Blood. 2016;127(20):2427-2438.
4. Marty FM, Ljungman P, Chemaly RF, et al. Letermovir prophylaxis for cytomegalovirus in hematopoietic-cell transplantation. N Engl J Med. 2017;377(25):
2433-2444.
5. Crough T, Khanna R. Immunobiology of human cytomegalovirus: from bench to bedside. Clin Microbiol Rev. 2009;22(1):76-98.
6. Camargo JF, Wieder E, Kimble E, et al. Functional signatures revealed by deep phenotyping of CMV-specific CD8+ T cells predict risk of early CMV reactivation after allogeneic hematopoietic cell transplantation [BMT Tandem Meetings abstract 93]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
Early HHV-6 Reactivation in CMV-Seronegative Cord Blood Transplant Recipients Is Associated With Inferior Relapse-Free and Overall Survival
Reactivation of the human herpesvirus 6 (HHV-6) is seen in most cord-blood transplant recipients. Reactivation is associated with delayed engraftment, encephalitis, graft-versus-host disease, and CMV.1-3 The mechanisms that lead to these events have not been fully described. Immunosuppression of transplant recipients enables reactivation of not only HHV-6, but other viruses as well, making it difficult to determine the specific effects of HHV-6 reactivation.
A retrospective study of patients treated at a single institution between July 2010 and May 2017 evaluated the impact of HHV-6, including its immunosuppressive activity, after cord blood transplant.4 To avoid the confounding influence of CMV, samples were restricted to consecutive CMV-seronegative recipients of cord blood. The study excluded patients with reactivation of CMV, adenovirus, Epstein-Barr virus, or BK virus. Early HHV-6 reactivation was defined as 1 or more positive quantitative DNA PCR tests on whole blood within 30 days after cord blood transplant. The absence of HHV-6 reactivation was defined as 1 or more negative PCR tests in the first 2 weeks and 1 or more negative PCR tests in the second 2 weeks after transplant. Research blood samples to evaluate T-cell populations by flow cytometry were collected on day 30 in a subset of patients. The primary endpoint was the rate of relapse.
Among the 152 patients, 120 (79%) tested positive for HHV-6. Patient characteristics such as age, sex, diagnosis, conditioning regimen, and CMV reactivation were generally well-balanced between the cohorts of patients who did relapse vs those who did not. Patients with HHV-6 reactivation by day 28 were significantly more likely to relapse (P=.03; Figure 7). HHV-6 relapse was not associated with conditioning intensity or CMV reactivation by day 30. The HHV-6–negative and HHV-6–positive cohorts showed similar rates of overall survival, relapse-free survival, and nonrelapse mortality. There was a nonsignificant trend toward a higher rate of acute graft-versus-host disease in the HHV-6–positive cohort. Rates of chronic graft-versus-host disease, however, were similar between the 2 groups. Flow cytometry indicated that natural killer cells did not appear to be involved in HHV-6 reactivation.
References
1. Aoki J, Numata A, Yamamoto E, Fujii E, Tanaka M, Kanamori H. Impact of human herpesvirus-6 reactivation on outcomes of allogeneic hematopoietic stem cell transplantation. Biol Blood Marrow Transplant. 2015;21(11):2017-2022.
2. Inazawa N, Hori T, Hatakeyama N, et al. Large-scale multiplex polymerase chain reaction assay for diagnosis of viral reactivations after allogeneic hematopoietic stem cell transplantation. J Med Virol. 2015;87(8):1427-1435.
3. Scheurer ME, Pritchett JC, Amirian ES, Zemke NR, Lusso P, Ljungman P. HHV-6 encephalitis in umbilical cord blood transplantation: a systematic review and meta-analysis. Bone Marrow Transplant. 2013;48(4):574-580.
4. Rashidi A, Ebadi M, Said B, et al. Early HHV-6 reactivation in CMV-seronegative cord blood transplant recipients is associated with inferior relapse-free and overall survival [BMT Tandem Meetings abstract 534]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
Cytomegalovirus Infection and Disease Incidence and Risk Factors Across Diverse Hematopoietic Cell Transplantation Platforms Using a Standardized Monitoring and Treatment Approach: A Comprehensive Evaluation From a Single Institution
Allogeneic HSCT is potentially curative for numerous hematologic disorders. However, the procedure requires suppression or ablation of the host immune system to facilitate engraftment of donor cells. Donor T cells must be removed, reduced, or suppressed to prevent graft-versus-host disease. As a result, the graft recipient is susceptible to viral infections after transplant. More than 40% of at-risk recipients (defined as those who were seropositive or whose donor was seropositive) experience infection within the first 100 days after transplant.
A retrospective study was conducted to characterize posttransplant CMV infection and disease across all HSCT protocols.1 The study evaluated the incidence, associated risk factors, and virus-associated nonrelapse mortality. Enrolled patients had undergone their first transplant and had follow-up data available through 1 year after the procedure, with at least 64% of weekly PCR results available through day 100 posttransplant. CMV infection was defined as 2 quantitative PCR results between 3.08 to 4.11 log10 IU/mL within a single week, 1 quantitative PCR value of greater than 4.11 log10 IU/mL, or sufficient clinical suspicion of CMV disease to prompt therapy. The duration of CMV infection was determined from weekly quantitative PCR values and length of treatment. Recurrent infection referred to patients who had previous evidence of CMV infection but in whom CMV was not detected for at least 4 weeks prior to the new infection.2
Among at-risk recipients, the cumulative incidence of CMV infection at 100 days posttransplant was 46%. The cumulative incidence of CMV infection varied mainly by recipient CMV serostatus (P<.0001).The estimates of infection at day 100 were 2% for patients who were donor- and recipient-negative, 6% for those who were donor-positive and recipient-negative, 38% for those who were donor-negative and recipient-positive, and 40% for those who were donor- and recipient-positive. In keeping with results from a separate study, donor and/or recipient serostatus appeared to be the main determinant of CMV infection.3 The 100-day cumulative incidence of CMV infection associated with cord blood was 64%, which was higher than that of bone marrow (39%) or peripheral blood stem cells (30%; P=.016). This result was expected based on the cord unit’s immature immune system and general lack of antiviral immunity.
The cumulative incidence of CMV infection at 100 days posttransplant was highest with cord-based T-cell manipulation (67%; P=.043) and lowest with calcineurin inhibitors and T-cell manipulation based on the mammalian target of rapamycin (mTOR; 41%; P<.001). The incidence of CMV infection was 61% in patients who received calcineurin inhibitors only vs 20% in those treated with a calcineurin inhibitor and an mTOR inhibitor (P<.001; Figure 8). The median duration of CMV therapy was longer for patients who had undergone HSCT with cord blood (36 days) compared with transplants using peripheral blood stem cells (21 days) or bone marrow (28.5 days; P=.03).
References
1. Marchalik R, Melendez-Munoz R, Jerussi T, et al. Cytomegalovirus (CMV) infection and disease incidence and risk factors across diverse hematopoietic cell transplantation (HCT) platforms using a standardized monitoring and treatment approach: a comprehensive evaluation from a single institution [BMT Tandem Meetings abstract 546]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
2. Ljungman P, Boeckh M, Hirsch HH, et al; Disease Definitions Working Group of the Cytomegalovirus Drug Development Forum. Definitions of cytomegalovirus infection and disease in transplant patients for use in clinical trials. Clin Infect Dis. 2017;64(1):87-91.
3. Teira P, Battiwalla M, Ramanathan M, et al. Early cytomegalovirus reactivation remains associated with increased transplant-related mortality in the current era: a CIBMTR analysis. Blood. 2016;127(20):2427-2438.
Clinical Impact and Burden of CMV Infection on the Use of Resources in Allogeneic Hematopoietic Cell Transplantation
Despite the standard use of preemptive therapy, CMV infection continues to be a major complication after allogeneic HSCT and is associated with increased transplant-related mortality.1 Novel anti-CMV therapies are in development to reduce the rates of CMV reactivation, infection, and disease. In addition to offering a clinically effective alternative to current antiviral agents, improved therapies could decrease the overall costs associated with CMV-related morbidity and mortality. The impact of CMV infection on cost and resource use has not been extensively examined. A retrospective study evaluated the impact of CMV infection on clinical outcomes and the use of resources.2 The study included all allogeneic HSCT recipients at a single center between 2009 and 2016. The median age of the 183 patients was 44 years (range, 16-68 years), and 59% were male. For nearly all of the patients, the transplant procedure was their first. It was the second transplant in 9 and the third in 2. The HSCT procedure used materials from an identical sibling donor in 45% of cases, cord blood in 30%, and an unrelated donor in 20%. The procedure was a haploidentical stem cell transplant in 5%. In 88% of cases, CMV serology indicated an at-risk transplant. The severity of graft-versus-host disease was low (grade 0 to 1) in 67% and high (grade 2 to 4) in the remainder (based on criteria from the Mount Sinai Acute GVHD International Consortium).
The median time to the first CMV reactivation was 35 days (range, 15-58 days). CMV reactivation was observed in 60% of at-risk patients, and the rate of CMV infection was 3.4 per 100 patient-months. At 2 years, overall survival was 59.9% in patients without CMV infection vs 44.4% in patients with CMV infection (P=.027; Figure 9). Pooled analysis showed a higher incidence of CMV infection in recipients of cord blood or haploidentical transplants vs patients who underwent matched related or unrelated transplants (68% vs 49%; P=.009). The cumulative incidence of CMV infection was significantly increased among the patients with high-grade acute graft-versus-host disease vs low-grade disease (87.2% vs 42.8%; P<.001). Patients who were older than the median age of 44 years at the time of the HSCT were more likely to develop CMV infection compared with younger patients (65.2% vs 48%; P=.005). Among the patients who developed a CMV infection, 57% had 2 or more infections and 20% had 4 or more. A CMV infection prolonged the duration of hospitalization by 30 days throughout the first year after transplant (P<.001). The length of stay in a hospital increased to more than 40 additional days in patients with 2 or more CMV infections (P<.001). Clinically significant adverse events associated with preemptive therapy were common after first-line treatment. The frequency of these events increased with second and subsequent lines of therapy.
References
1. Teira P, Battiwalla M, Ramanathan M, et al. Early cytomegalovirus reactivation remains associated with increased transplant-related mortality in the current era: a CIBMTR analysis. Blood. 2016;127(20):2427-2438.
2. de Miguel C, Cruz JL, Portero MF, et al. Clinical impact and burden of CMV infection on the use of resources in allogeneic hematopoietic cell transplantation [BMT Tandem Meetings abstract 565]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
Highlights in Cytomegalovirus From the 2018 BMT Tandem Meetings: Commentary
Sanjeet Singh Dadwal, MD
Associate Clinical Professor of Medicine
Division of Infectious Disease
Head, Antimicrobial Stewardship Program
Co-Lead, Infectious Disease, Transplant Disease Team
City of Hope National Medical Center
Duarte, California
Several abstracts at the 2018 BMT Tandem Meetings provided important data in the management of cytomegalovirus (CMV) infection among patients undergoing hematopoietic cell transplant (HCT). The presentations reported on the burden of CMV reactivation in various HCT populations, evaluated prophylactic regimens, calculated cost and clinical burden related to reactivation, and explored the potential of biomarker signatures to determine CMV immunity.
CMV Infection (Reactivation)
Multiple abstracts presented at the 2018 BMT Tandem Meetings continued to confirm a high cumulative incidence of CMV infection (defined as detectable virus with no evidence of end-organ disease) in the first 100 days after allogeneic HCT. Dr Rachel Marchalik and colleagues evaluated the effect of T-cell manipulation on the cumulative incidence of CMV infection in the first 100 days after the procedure.1 The overall incidence of CMV infection was 46%. The incidence was highest with cord-based T-cell manipulation (67%) and lowest with manipulation based on calcineurin and mammalian target of rapamycin (mTOR) inhibition (41%).
Dr Roni Tamari and coworkers examined CMV infection in patients who underwent CD34-selected allogeneic HCT.2 Patients with CD34-selected grafts had a higher risk of CMV infection compared with those who received unmanipulated grafts, and this risk manifested earlier in the post-HCT period. Among patients with CD34-selected grafts and CMV infection, the absolute neutrophil count was lower, suggesting that active infection impacts allografts, with resultant cytopenia. This abstract highlights the burden of CMV, and the authors concluded that there is the need for an effective nonmyelosuppressive prophylactic agent to prevent CMV infection to avoid the downstream effects of CMV infection and its treatment.
An important area of research is the measurement of CMV immunity, with the objective of identifying patients in whom CMV is likely to reactivate vs patients who are likely to successfully clear the viremia. Dr Jose Camargo and colleagues evaluated cytokine signatures of CD8 T-cell response to pp65 and IE1 CMV peptide stimulation.3 They identified a protective signature and a nonprotective signature, which can help distinguish between patients at higher risk for CMV infection and those who can spontaneously control infection. These findings are interesting, but the clinical applications will require further study. Perhaps a targeted approach to prophylaxis against CMV infection could employ such intervention in the future.
CMV Infection Prophylaxis
CMV infection has a significant impact on clinical outcome and is associated with high cost. High rates of morbidity and all-cause mortality are seen in patients who develop resistant or refractory infection. Without a safe and effective prophylactic agent, preemptive therapy has been the standard of care in the management of CMV infection. This approach is highly efficacious, but not without side effects. Rates of CMV infection after allogeneic HCT are highest in recipients who are seropositive.4 Preemptive treatment for CMV infection is indicated when levels of viral load measured by polymerase chain reaction testing hit a certain threshold. The traditional approaches for preemptive treatment have been ganciclovir or foscarnet. However, both of these therapies are associated with toxicities ranging from myelosuppression with ganciclovir to nephrotoxicity with foscarnet.5,6
In the absence of an effective anti-CMV prophylaxis agent, various centers have used combinations of ganciclovir and acyclovir for prevention of CMV reactivation.
High-Intensity Prophylactic Regimens
One common high-intensity prophylactic regimen consists of ganciclovir given before transplant followed by high-dose acyclovir given after the procedure. In 2011, a study evaluated the use of ganciclovir administered before umbilical cord blood transplant (5 mg/kg intravenously daily from day −8 to day −2) and high-dose acyclovir (2 g, 3 times daily) after the procedure in high-risk, CMV-seropositive patients.7 The study showed that this intensive prevention regimen significantly decreased CMV infection and disease. Recently, Dr Joshua Hill and colleagues from the same center evaluated a modified high-dose strategy that eliminated pretransplant use of ganciclovir.8 The authors found no difference in outcomes as compared with the regimen that included pretransplant ganciclovir. A similar study, presented by Dr Carmen Lau and colleagues, also showed no benefit with the use of ganciclovir prior to transplant.9
Letermovir
Previously, the quest for a safe and effective prophylactic agent had been elusive. Clinical trials evaluating maribavir and CMX001 (brincidofovir) failed to meet their primary endpoints of preventing CMV infection.10,11 In November 2017, the US Food and Drug Administration (FDA) approved letermovir for the prophylaxis of CMV infection in adult CMV-seropositive recipients undergoing HCT.12 Letermovir is an inhibitor of the enzyme “terminase,” and it is nonmyelosuppressive and nonnephrotoxic. A presentation by Dr Cameron Douglas and colleagues at the BMT Tandem Meetings showed that although polymorphisms in the UL56 gene exist, they do not appear to impact sensitivity to letermovir.13 In the pivotal study, only 1 patient in the full analysis set had a V236M mutation that conferred resistance to letermovir.14 Also, there was no cross resistance to ganciclovir or foscarnet. Letermovir may play a significant role in the prevention of CMV infection, when used as suggested according to the FDA indication.
Morbidity and Mortality
From an epidemiologic standpoint, resistant or refractory CMV infection can lead to significant morbidity. Dr Annette Artau and coworkers evaluated outcomes after resistant or refractory CMV infection among patients who underwent allogeneic HCT.15 There was a high burden of CMV disease among the 81 patients, with an incidence of 49%. All-cause mortality was also high, at 64%. Patients developed resistance to ganciclovir at a median of 153 days post-HCT and to foscarnet at a median of 98 days post-HCT. Refractory CMV infection developed at a median of 64 days after transplant. Whether prophylaxis with letermovir can prevent such reactivation early on and have an impact on the disease after day 100 remains to be seen.
Economic Burden
Several abstracts presented at the meeting evaluated the clinical and economic burden of CMV reactivation. Dr Shashank Ghantoji and colleagues showed that significant costs are associated with the preemptive use of ganciclovir or foscarnet to treat CMV infection among hospitalized patients.16 The per episode cost was $6096 for intravenous immune globulin, $2410 for foscarnet, $836 for ganciclovir, and $780 for valganciclovir. Serious side effects were seen in 35% of patients treated with ganciclovir and 12% of patients treated with foscarnet. Dr Carlos de Miguel and coworkers evaluated clinical outcomes and resource use associated with CMV infection.17 They also found that reactivation is associated with a substantial use of resources. Both of these studies suggest that new strategies are needed.
Additionally, Dr Jonathan Schelfhout and colleagues presented results from a study using a model evaluating the cost effectiveness of letermovir as prophylaxis among patients who underwent allogeneic HCT.18 The cost was $23,270 for each life-year gained and $25,222 for each quality-adjusted life-year gained. The model suggested that letermovir may be associated with longer life, improved health-related quality of life, and fewer adverse outcomes. The authors noted that the costs of letermovir were partially offset by decreases in costs associated with preemptive therapy, CMV-related rehospitalization, and graft-versus-host disease.
Conclusion
The abstracts on CMV infection presented at the 2018 BMT Tandem Meetings highlighted the continued burdens—both clinical and economic—that arise from early CMV reactivation in allogeneic HCT recipients. The field is showing rapid progress in several areas, with continued epidemiologic investigations, studies of novel means of CMV immune monitoring, and updates on high-intensity prophylaxis. Researchers at MD Anderson Cancer Center generated robust data on the economic burden of early CMV infection,16 and others are devising health care economic models based on the use of letermovir for the prevention of CMV infection.18 With the FDA approval of letermovir for the prevention of CMV infection, as well as vaccines and other advances, the field of CMV infection is on the verge of a major transformation.
Disclosure
Dr Dadwal is a consultant and a member of the advisory board and speakers bureau of Merck. He has received research funding from GSK, Gilead, Ansun BioPharma, Oxford Immunotec, AiCuris, and Shire.
References
1. Marchalik R, Melendez-Munoz R, Jerussi T, et al. Cytomegalovirus (CMV) infection and disease incidence and risk factors across diverse hematopoietic cell transplantation (HCT) platforms using a standardized monitoring and treatment approach: a comprehensive evaluation from a single institution [BMT abstract 546]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
2. Tamari R, Cho C, Hilden P, et al. CMV reactivation post CD34+ selected all-HCT has adverse outcomes on blood counts recovery [BMT abstract 540]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
3. Camargo JF, Wieder E, Kimble E, et al. Functional signatures revealed by deep phenotyping of CMV-specific CD8+ T cells predict risk of early CMV reactivation after allogeneic hematopoietic cell transplantation [BMT abstract 93]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
4. Teira P, Battiwalla M, Ramanathan M, et al. Early cytomegalovirus reactivation remains associated with increased transplant-related mortality in the current era: a CIBMTR analysis. Blood. 2016;127(20):2427-2438.
5. Goodrich JM, Bowden RA, Fisher L, Keller C, Schoch G, Meyers JD. Ganciclovir prophylaxis to prevent cytomegalovirus disease after allogeneic marrow transplant. Ann Intern Med. 1993;118(3):173-178.
6. Bregante S, Bertilson S, Tedone E, et al. Foscarnet prophylaxis of cytomegalovirus infections in patients undergoing allogeneic bone marrow transplantation (BMT): a dose-finding study. Bone Marrow Transplant. 2000;26(1):23-29.
7. Milano F, Pergam SA, Xie H, et al. Intensive strategy to prevent CMV disease in seropositive umbilical cord blood transplant recipients. Blood. 2011;118(20):5689-5696.
8. Hill JA, Pergam SA, Cox E, et al. A modified intensive strategy to prevent CMV disease in seropositive umbilical cord blood transplant recipients [BMT abstract 96]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
9. Lau C, Politikos I, Devlin S, et al. Analysis of cytomegalovirus (CMV) infections in the first 180 days in adult sero-positive cord blood transplantation (CBT) recipients reveals high infection rates and treatment burden [BMT abstract 549]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
10. Marty FM, Ljungman P, Papanicolaou GA, et al; Maribavir 1263-300 Clinical Study Group. Maribavir prophylaxis for prevention of cytomegalovirus disease in recipients of allogeneic stem-cell transplants: a phase 3, double-blind, placebo-controlled, randomised trial. Lancet Infect Dis. 2011;11(4):284-292.
11. Marty FM, Winston DJ, Chemaly RF, et al. Brincidofovir for prevention of cytomegalovirus (CMV) after allogeneic hematopoietic cell transplantation (HCT) in CMV-seropositive patients: a randomized, double-blind, placebo-controlled, parallel-group phase 3 trial [BMT abstract 5]. Biol Blood Marrow Transplant. 2016;22(3 suppl).
12. PREVYMIS (letermovir) tablets and PREVYMIS (letermovir) injection. US Food and Drug Administration. https://www.accessdata.fda.gov/drugsatfda_docs/nda/2017/209939Orig1s000,209940Orig1s000TOC.cfm. Posted December 18, 2017. Accessed March 28, 2018.
13. Douglas CM, Levitan D, Maguire M, et al. Letermovir resistance genotyping in a clinical trial of cytomegalovirus prophylaxis for hematopoietic cell transplant recipients [BMT abstract 72]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
14. Marty FM, Ljungman P, Chemaly RF, et al. Letermovir prophylaxis for cytomegalovirus in hematopoietic-cell transplantation. N Engl J Med. 2017;377(25):2433-2444.
15. Artau A, Aitken S, El Chaer F, et al. Outcomes of resistant or refractory CMV infection in recipients of allogeneic hematopoietic cell transplant [BMT abstract 560]. Biol Blood Marrow Transplant. 2018;24(3)s(suppl 1).
16. Ghantoji SS, Schelfhout J, El Haddad L, et al. Clinical & economic burden of pre-emptive therapy (PET) of cytomegalovirus (CMV) infection in hospitalized allogeneic hematopoietic cell transplant (allo-HCT) recipients: the MD Anderson Cancer Center experience [BMT abstract 542]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
17. de Miguel C, Cruz JL, Portero MF, et al. Clinical impact and burden of CMV infection on the use of resources in allogeneic hematopoietic cell transplantation [BMT abstract 565]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).
18. Schelfhout J, Jiang Y, Miles L, Merchant S, Graham J. Cost effectiveness of letermovir in prevention of clinically significant CMV infection in CMV seropositive allogeneic hematopoietic stem cell transplant recipients [BMT abstract 557]. Biol Blood Marrow Transplant. 2018;24(3)(suppl 1).