Differential outcome of neurological HCMV infection in two hematopoietic stem cell transplant recipients

All T-cell depleted HSCT recipients undergo frequent virologic monitoring associated with pre-emptive treatment protocols for most common viral infections, such as HCMV [7], EBV [8, 9], and adenovirus [10].

In more detail, in the absence of active HCMV infection or GVHD, real-time PCR for HCMV DNA quantification in whole blood [11, 12] is performed once a week in the first three months post-transplant, once every two weeks in the next three months and once every four weeks in the next six months. In the presence of active HCMV infection or GVHD, real-time PCR is performed twice a week. Treatment with GCV was initiated upon detection of 10,000 HCMV DNA copies in whole blood [12, 13].

The emergence of GCV- and PFA-resistant HCMV strains is monitored by sequencing HCMV UL97 and UL54 genes [14].

In all pediatric patients receiving haploidentical HSCT, HCMV- EBV- and adenovirus- specific donor derived CTLs are generated before transplantation and administered in case of refractory infections [10, 15].

A HCMV-seropositive 58 year old man with high-risk acute myeloid leukemia received a matched unrelated HSCT from a HCMV-seronegative donor. Transplant conditioning included 200 cGy total body irradiation (TBI), fludarabine, alemtuzumab and melphalan. Cyclosporine and a short course of methotrexate were given as prophylaxis against GVHD. After engraftment, the patient presented with three recurrent asymptomatic HCMV DNAemia episodes (>10,000 copies/mL) and pre-emptive treatment (GCV 5 mg/kg/twice a day) was administered at days 15–35, days 69–74 and days 85–93. Nine months after transplant, prednisone (50 mg/Kg/once a day), polyclonal immunoglobulins (400 mg/Kg/ every four days) and rituximab (RTX) (600 mg/once a week) were administered to treat thrombocytopenia (PLT 14.000/μL) in the presence of antibodies to platelet membrane glycoproteins (GPIb/IX and GP IIb/IIIa). On day 396, two months after the last of four RTX doses, the patient showed progressive memory deficit, temporal disorientation, astenia and weight loss. Expansion of the NK cell subset (1,449 cells/μL), reduced CD4 (132 cells/μL) and CD8 (79.5 cells/μL) T-cell counts and depletion of CD19 cells (0 cells/μL) were observed. Brain Magnetic Resonance Imaging (MRI) showed several foci of restricted diffusion along the ventricles and the ependyma, consistent with encephalitis. Despite blood brain barrier damage (albumin 877 mg/L CSF), a higher HCMV DNA level (346,780 copies/mL) in CSF than in blood (8,100 copies/mL) was observed. GCV treatment (5 mg/kg/ twice a day) was initiated. On day 407, the emergence of a GCV-resistant HCMV strain was hypothesized based on fever and dyspnoea: thus, GCV was empirically substituted with PFA (90 mg/kg/ twice a day). On day 418, HCMV DNA became undetectable in blood, but persisted at a high level in CSF (88,920 copies/mL) and PFA treatment was supplemented with anti-HCMV immunoglobulins. Meanwhile, Staphylococcus epidermidis was isolated in a blood culture. Subsequently, teicoplanin therapy was associated with disappearance of fever and dyspnoea. Sequencing of HCMV UL97 and UL54 showed the absence of drug-resistant HCMV strains in blood or CSF. However, the patient experienced progressive deterioration in neurological function, accompanied by a worsening of the brain MRI. On day 449 after transplantation, HCMV DNA persisted at a high level in CSF (102,860 copies/mL) in parallel with severe blood brain barrier damage (albumin 1,310 mg/L). Severe lymphopenia with a predominance of NK cells (228 cells/μL), low numbers of CD8 (5.4 cells/μL) and CD4 T-cells (8.5 cells/μL), and a complete absence of B-cells was observed. Two days later, the patient became unresponsive, developed fever and eventually died. The virologic follow-up is summarized in Figure 1A.

A HCMV-seronegative 4 year old girl who received a haploidentical T-cell depleted HSCT from a HCMV-seropositive donor to treat an acute lymphoblastic leukaemia (ALL), which had relapsed five months before. Transplant conditioning included TBI, fludarabine, thiotepa and antithymocyte globulin. No GVHD prophylaxis was administered. After engraftment, on day 24, an HCMV infection was detected in blood (2 pp65-positive cells/200,000 cells) and treatement with PFA (90 mg/kg/twice a day) was initiated. Despite antiviral treatment, HCMV viral load increased (100,500 DNA copies/mL blood on day 59) and donor HCMV-specific CTLs were infused on days 59, 80 and 97. From day 97, GCV (5 mg/kg/ twice a day) was added to PFA. Persistent fever was present from day 90. On day 102, very low CD4 (39 cells/μL) and CD8 (33 cells/μL) T-cell counts were observed. On day 105, cutaneous GVHD was diagnosed, and methylprednisolone (1.5 mg/kg/once a day) was administered, followed by tacrolimus (1 g/once a day) and three doses of polyclonal immunoglobulin. On day 106, the patient reported acute cervical and right knee pain, accompanied by fever, asthenia and headache. X-ray and CT scan did not show skeletal or neurologic trauma. Tramadol hydrochloride (15 mg intravenously), ketorolac tromethamine (8 mg intravenously) were ineffective in controlling pain and morphine (2 mg intravenously) was infused on day 106. A high HCMV DNA load (495,900 copies/mL) was detected in CSF in contrast with 9,200 HCMV DNA copies/mL in blood. Sequencing of HCMV UL97 and UL54 showed the absence of drug-resistant HCMV strains in blood or CSF. On day 114 the neurological picture improved, but two weeks later viral load was still elevated. GCV was undetectable in plasma, while it was present at a low basal concentration (0.55 μg/mL) in CSF. On day 132, GCV was administered at an increased dosage of 7.5 mg/kg twice a day. HCMV DNA load declined progressively until disappearance, initially in blood (day 132) and then in CSF (day 158). From day 150, T-lymphocyte reconstitution was observed (CD4, 115 cells/μL and CD8, 88 cells/μL, followed by CD4, 208 cells/μL and CD8, 397 cells/μL on day 181). Unfortunately, on day 214, the patient relapsed ALL and died one month later. The virologic follow-up is summarized in Figure 1B.