Humoral and cellular responses to SARS-CoV-2 in patients with B-cell haematological malignancies improve with successive vaccination.

Patients with haematological malignancies are more likely to have poor responses to vaccination. Here we provide detailed analysis of the humoral and cellular responses to COVID-19 vaccination in 69 patients with B-cell malignancies. Measurement of anti-spike IgG in serum demonstrated a low seroconversion rate with 27.1% and 46.8% of patients seroconverting after the first and second doses of vaccine, respectively. In vitro pseudoneutralisation assays demonstrated a poor neutralising response, with 12.5% and 29.5% of patients producing a measurable neutralising titre after the first and second doses, respectively. A third dose increased seropositivity to 54.3% and neutralisation to 51.5%, while a fourth dose further increased both seropositivity and neutralisation to 87.9%. Neutralisation titres post-fourth dose showed a positive correlation with the size of the B-cell population measured by flow cytometry, suggesting an improved response correlating with recovery of the B-cell compartment after B-cell depletion treatments. In contrast, interferon gamma ELISpot analysis showed a largely intact T-cell response, with the percentage of patients producing a measurable response boosted by the second dose to 75.5%. This response was maintained thereafter, with only a small increase following the third and fourth doses, irrespective of the serological response at these timepoints.

Clinical outcomes and risk factors for severe COVID-19 in patients with haematological disorders receiving chemo- or immunotherapy.

Haematology patients receiving chemo- or immunotherapy are considered to be at greater risk of COVID-19-related morbidity and mortality. We aimed to identify risk factors for COVID-19 severity and assess outcomes in patients where COVID-19 complicated the treatment of their haematological disorder. A retrospective cohort study was conducted in 55 patients with haematological disorders and COVID-19, including 52 with malignancy, two with bone marrow failure and one immune-mediated thrombotic thrombocytopenic purpura (TTP). COVID-19 diagnosis coincided with a new diagnosis of a haematological malignancy in four patients. Among patients, 82% were on systemic anti-cancer therapy (SACT) at the time of COVID-19 diagnosis. Of hospitalised patients, 37% (19/51) died while all four outpatients recovered. Risk factors for severe disease or mortality were similar to those in other published cohorts. Raised C-reactive protein at diagnosis predicted an aggressive clinical course. The majority of patients recovered from COVID-19, despite receiving recent SACT. This suggests that SACT, where urgent, should be administered despite intercurrent COVID-19 infection, which should be managed according to standard pathways. Delay or modification of therapy should be considered on an individual basis. Long-term follow-up studies in larger patient cohorts are required to assess the efficacy of treatment strategies employed during the pandemic.

Recipients Receiving Better HLA-Matched Hematopoietic Cell Transplantation Grafts, Uncovered by a Novel HLA Typing Method, Have Superior Survival: A Retrospective Study.

HLA matching at an allelic-level resolution for volunteer unrelated donor (VUD) hematopoietic cell transplantation (HCT) results in improved survival and fewer post-transplant complications. Limitations in typing technologies used for the hyperpolymorphic HLA genes have meant that variations outside of the antigen recognition domain (ARD) have not been previously characterized in HCT. Our aim was to explore the extent of diversity outside of the ARD and determine the impact of this diversity on transplant outcome. Eight hundred ninety-one VUD-HCT donors and their recipients transplanted for a hematologic malignancy in the United Kingdom were retrospectively HLA typed at an ultra-high resolution (UHR) for HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1 using next-generation sequencing technology. Matching was determined at full gene level for HLA class I and at a coding DNA sequence level for HLA class II genes. The HLA matching status changed in 29.1% of pairs after UHR HLA typing. The 12/12 UHR HLA matched patients had significantly improved 5-year overall survival when compared with those believed to be 12/12 HLA matches based on their original HLA typing but were found to be mismatched after UHR HLA typing (54.8% versus 30.1%, P = .022). Survival was also significantly better in 12/12 UHR HLA-matched patients when compared with those with any degree of mismatch at this level of resolution (55.1% versus 40.1%, P = .005). This study shows that better HLA matching, found when typing is done at UHR that includes exons outside of the ARD, introns, and untranslated regions, can significantly improve outcomes for recipients of a VUD-HCT for a hematologic malignancy and should be prospectively performed at donor selection.

CMV promotes recipient T-cell immunity following reduced-intensity T-cell-depleted HSCT, significantly modulating chimerism status.

Cytomegalovirus (CMV) remains a significant cause of morbidity after allogeneic hematopoietic stem cell transplantation (HSCT). Clinical risk varies according to a number of factors, including recipient/donor CMV serostatus. Current dogma suggests risk is greatest in seropositive recipient (R+)/seronegative donor (D-) transplants and is exacerbated by T-cell depletion. We hypothesized that in the setting of reduced-intensity T-cell-depleted conditioning, recipient-derived CMV-specific T cells escaping deletion may contribute significantly to CMV-specific immunity and might therefore also influence chimerism status. We evaluated 105 recipients of alemtuzumab-based reduced-intensity HSCT and collated details on CMV infection episodes and T-cell chimerism. We used CMV-specific HLA multimers to enumerate CMV-specific T-cell numbers and select cells to assess chimerism status in a subset of R+/D- and R+/seropositive donor patients. We show that in R+/D- patients, CMV-specific T cells are exclusively of recipient origin, can protect against recurrent CMV infections, and significantly influence the chimerism status toward recipients. The major findings were replicated in a separate validation cohort. T-cell depletion in the R+/D- setting may actually, therefore, foster more rapid reconstitution of protective antiviral immunity by reducing graft-vs-host directed alloreactivity and the associated elimination of the recipient T-cell compartment. Finally, conversion to donor chimerism after donor lymphocytes is associated with clinically occult transition to donor-derived immunity.

Impact of Pretransplantation (18)F-Fluorodeoxyglucose-Positron Emission Tomography on Survival Outcomes after T Cell-Depleted Allogeneic Transplantation for Hodgkin Lymphoma.

Pretransplant (18)F-fluorodeoxyglucose (FDG) positron emission tomography status is an important prognostic factor for outcomes after autologous stem cell transplantation (SCT) in Hodgkin lymphoma (HL), but its impact on outcomes after allogeneic SCT remains unclear. We retrospectively evaluated outcomes after T cell-depleted allogeneic SCT of 116 patients with nonprogressive HL according to pretransplant Deauville scores. Endpoints were overall survival (OS), progression-free survival (PFS), relapse rate (RR), and nonrelapse-related mortality (NRM). OS, PFS, and RR did not differ significantly between the Deauville 1 to 2 and Deauville 3 to 5 cohorts (OS: 77.5% versus 67.3%, P = .49; PFS: 59.4% versus 55.7%, P = .43; RR: 20.9% versus 22.6%, P = .28 at 4 years). Differences in PFS remained statistically nonsignificant when comparisons were made between Deauville 1 to 3 and Deauville 4 to 5 cohorts (60.9% versus 51.4%, P = .10), and RR remained very similar (21.5% versus 23.8%, P = .42). Multivariate analyses demonstrated trends toward significance for an effect of Deauville score on PFS (hazard ratio 1.82 for Deauville 4 to 5, P = .06) and for number of lines of prior therapy on OS (hazard ratio 2.34 for >5 lines, P = .10). The latter effect appeared to be driven by higher NRM rather than increased RR. Our findings suggest that Deauville score before allogeneic SCT in patients with nonprogressive HL has a relatively modest impact on survival outcomes in comparison with the impact in autologous SCT and that predictive values for the individual patient remain low, indicating that residual FDG-avid disease should not preclude allogeneic SCT. Furthermore, our findings bring into question the importance of attainment of metabolic complete response in this setting if it is at the expense of increasing NRM risk.

Autologous stem cell transplantation outcomes in elderly patients with B cell Non-Hodgkin Lymphoma.

The precise role of autologous haematopoietic stem cell transplantation (ASCT) remains unclear in patients over 60 years of age. There is potential for increased procedural morbidity and mortality, and differences in disease biology that could impact outcomes. We performed a retrospective single-centre review of 81 elderly B-cell Non-Hodgkin Lymphoma patients undergoing ASCT. Five-year overall survival (OS) and progression-free survival (PFS) was 54·7% and 49·1% respectively. Non-relapse mortality (NRM) at 100 days and 1 year was 1·3% and 2·5%, suggesting no major excess compared to younger cohorts. OS and PFS were significantly worse in those over 65 years compared to those aged 60-64 (47·6% vs. 57·7%, P = 0·0437, and 27·6% vs. 57·7%, P = 0·0052 at 5 years). This resulted largely from an increased relapse risk (RR) (53·8% vs. 30·1%, P = 0·0511) rather than excess NRM, and age remained independently significant for PFS on multivariate analyses [Hazard ratio 2·56 (1·35-4·84, P = 0·0052) for PFS and 1·89 (0·99-3·61, P = 0·054) for OS]. Our data adds to the growing body of evidence demonstrating that ASCT can be an effective treatment strategy with an acceptable safety profile in selected elderly patients. Further evaluation of its overall benefit is warranted, however, in those over 65 years of age, as RR appears to be considerably higher.

Autologous stem cell transplantation for follicular lymphoma is of most benefit early in the disease course and can result in durable remissions, irrespective of prior rituximab exposure.

The role of autologous stem cell transplantation (ASCT) and the optimal timing of such transplants in patients with follicular lymphoma (FL) remains contentious. We present a single-centre experience documenting the outcomes of 70 FL patients who underwent BEAM (carmustine, cytarabine, etopside, melphalan)-conditioned ASCT between 1988 and 2009. With a median follow-up of 6·8 years (0·1-19·2), the 7-year overall survival (OS) and progression-free survival (PFS) from the date of ASCT was 76% and 60%, respectively. A significant difference in OS was found when comparing the patients transplanted in first or second remission versus those transplanted in later remissions (P = 0·02) and this significance was maintained when OS was calculated from the date of diagnosis (P = 0·03). There was a plateau on the PFS curves for patients transplanted in either first or second remissions after 9·3 and 6·4 years respectively, suggesting that these groups may never relapse. No differences were seen in OS or PFS in those treated with rituximab prior to transplant versus those who were not. Our data shows that BEAM ASCT can be a highly effective treatment in patients with FL early in the disease course, and that a proportion of patients experience prolonged disease-free survival and may be cured.

Allogeneic transplantation in the UK: an aggregation of marginal gains?

A number of advances in clinical practice that are considered routine in modern allogeneic transplant programmes lack definitive supporting evidence, partly because they may offer modest incremental benefits that are difficult to demonstrate in a statistically robust manner given the relatively small cohorts of patients who undergo such procedures. Nevertheless, these marginal gains probably contribute therapeutically meaningful overall benefit, particularly when aggregated. We review the evidence for a number of these practices in terms of impact on transplant outcomes, with particular reference to the setting of T cell depletion as widely practiced in the United Kingdom, including high resolution tissue typing, surveillance for and therapy of infectious complications, chimerism-directed immune modulation and more sensitive monitoring for residual or progressive disease.

Improved intensive care unit survival for critically ill allogeneic haematopoietic stem cell transplant recipients following reduced intensity conditioning.

The use of allogeneic haematopoietic stem cell transplantation (Allo-HSCT) is a standard treatment option for many patients with haematological malignancies. Historically, patients requiring intensive care unit (ICU) admission for transplant-related toxicities have fared extremely poorly, with high ICU mortality rates. Little is known about the impact of reduced intensity Allo-HSCT conditioning regimens in older patients on the ICU and subsequent long-term outcomes. A retrospective analysis of data collected from 164 consecutive Allo-HSCT recipients admitted to ICU for a total of 213 admissions, at a single centre over an 11·5-year study period was performed. Follow-up was recorded until 31 March 2011. Autologous HSCT recipients were excluded. In this study we report favourable ICU survival following Allo-HSCT and, for the first time, demonstrate significantly better survival for patients who underwent Allo-HSCT with reduced intensity conditioning compared to those treated with myeloablative conditioning regimens. In addition, we identified the need for ventilation (invasive or non-invasive) as an independently significant adverse factor affecting short-term ICU outcome. For patients surviving ICU admission, subsequent long-term overall survival was excellent; 61% and 51% at 1 and 5 years, respectively. Reduced intensity Allo-HSCT patients admitted to ICU with critical illness have improved survival compared to myeloablative Allo-HSCT recipients.

Risk-stratified adoptive cellular therapy following allogeneic hematopoietic stem cell transplantation for advanced chronic lymphocytic leukaemia.

Following reduced intensity-conditioned allogeneic stem cell transplantation (RIC allo-SCT) for chronic lymphocytic leukaemia (CLL), there is an inverse relationship between relapse and extensive chronic graft-versus-host disease (GVHD). We evaluated outcomes in 50 consecutive patients with CLL using the approach of alemtuzumab-based RIC allo-SCT and pre-emptive donor lymphocyte infusions (DLI) for mixed chimerism or minimal residual disease (MRD), with the intention of reducing the risk of GVHD. Forty two patients had high-risk disease, including 30% with 17p deletion (17p-). Of patients who were not in complete remission (CR) entering transplant, 83% subsequently achieved MRD-negative CR. Both MRD detection and uncorrected mixed chimerism were associated with greater risks of treatment failure. Nine of sixteen patients receiving DLI for persistent or relapsed disease subsequently attained MRD-negative CR. With a median follow-up of 4.3 years, 4-year current progression-free survival was 65% and overall survival was 75% (60% and 61% in respectively, patients with 17p-). DLI was associated with a 29% cumulative incidence of severe GVHD and mortality of 6.4%. At last follow-up, 83% of patients in CR were off all immunosuppressive treatment. In conclusion, the directed delivery of allogeneic cellular therapy has the potential to induce durable remissions in high-risk CLL without incurring excessive GVHD.

Adenoviremia has limited clinical impact in the majority of patients following alemtuzumab-based allogeneic stem cell transplantation in adults.

BACKGROUND: Adenovirus infection is a potentially serious complication of allogeneic hematopoietic stem cell transplantation (HSCT) and has been reported to occur more frequently following T-cell-depleted reduced-intensity HSCT. However, the true incidence and clinical significance as well as the relationship of disease to viremic titer remain unclear due to wide variation in study populations and methodology. METHODS: We performed weekly surveillance blood testing by quantitative polymerase chain reaction on all adult recipients of alemtuzumab-based reduced-intensity HSCT at our institution between January 2008 and January 2011. We collated this with clinical data on treatment and outcomes of adenovirus infection. RESULTS: Of 116 HSCT patients analyzed, 14 (12.1%) had adenoviremia with a titer >200 copies/mL. Median time to first detectable titer was 28 days post-HSCT (range, 10-347), and median time to maximum titer was 49 days (range, 16-368). Underlying disease diagnosis (lymphoid > myeloid) and recipient cytomegalovirus (CMV) serostatus (positive > negative) were significantly correlated with adenoviremia. Only 5 patients (with high peak titers of 99 000-2 500 000 copies/mL) received cidofovir; 1 died from complications relating to adenovirus and concurrent CMV infection. CONCLUSIONS: We detected adenoviremia at quantifiable levels in only 12.1% of HSCT patients. Attributable mortality was low (0.9% of the entire cohort, 7% of those with adenoviremia) because even infections associated with high viral titers responded to reduction in immunosuppression and treatment with cidofovir in the majority. The clinical significance of adenoviral infection in patients receiving alemtuzumab-based HSCT appears to be less than that previously reported, and only rarely does infection lead to significant morbidity and mortality.

Predominant or complete recipient T-cell chimerism following alemtuzumab-based allogeneic transplantation is reversed by donor lymphocytes and not associated with graft failure.

The clinical significance of mixed chimerism following allogeneic haematopoietic stem cell transplantation (HSCT) remains controversial. Its relevance and incidence are probably influenced by the conditioning regimen and incorporation of T-cell depletion. The presence of recipient chimerism levels >40-50% following T-cell replete reduced intensity transplantation correlates with a high risk of graft rejection, regardless of donor-lymphocyte infusions, but it is unclear whether this finding translates to T-cell depleted transplants. We conducted a retrospective single-institution analysis of patients receiving alemtuzumab-based HSCT. 27/152 (18%) evaluable cases had predominantly recipient T-cell chimerism at 3 months or beyond. By contrast, coincident chimerism in the granulocyte lineage was predominantly of donor origin (median 100%) in all but one patient. Donor lymphocyte infusion effectively converted predominantly recipient T-cell chimerism to ful donor chimerism in all evaluable cases including three cases with no detectable donor T cells. The only graft failure occurred in the patient with predominantly recipient myeloid chimerism in whom rejection occurred rapidly before donor lymphocytes could be administered. We conclude that predominant or complete recipient T-cell chimerism following alemtuzumab-based regimens does not have the same clinical implications as that following T-cell replete transplants and can be effectively converted with donor lymphocytes without the need for lympho-depleting agents or re-conditioning.

HLA-mismatched unrelated donors are a viable alternate graft source for allogeneic transplantation following alemtuzumab-based reduced-intensity conditioning.

The impact of human leukocyte antigen (HLA) mismatch after reduced-intensity conditioning allogeneic hematopoietic stem cell transplantation (RIT) using unrelated donors (UD) is unclear, and may be modulated by T-cell depletion. We therefore examined outcomes of 157 consecutive patients undergoing RIT after uniform conditioning with fludarabine, melphalan, and alemtuzumab (FMC). Donors were 10/10 HLA-matched (MUDs, n = 107) and 6 to 9/10 HLA-matched (MMUDs, n = 50), with no significant differences in baseline characteristics other than increased cytomegalovirus seropositivity in MMUDs. Rates of durable engraftment were high. Graft failure rates (persistent cytopenias with donor chimerism) were similar (8% vs 3%, P = .21), though rejection (recipient chimerism) was more frequent in MMUDs (8% vs 0%, P < .01). There were no significant differences between donors in the incidences of acute graft-versus-host disease (GVHD; 20% vs 22% grade 2-4, respectively, P = .83), chronic extensive GVHD (3-year cumulative incidence [CI] 23% vs 24%, P = .56), or treatment-related mortality (1-year CI 27% vs 27%, P = .96). Furthermore, there was no difference in 3-year overall survival (OS; 53% vs 49%, P = .44). Mismatch occurred at the antigenic level in 40 cases. The outcome in these cases did not differ significantly from the rest of the cohort. We conclude that RIT using HLA-mismatched grafts is a viable option using FMC conditioning.

Prognostic role of PET scanning before and after reduced-intensity allogeneic stem cell transplantation for lymphoma.

Allogeneic stem cell transplantation (SCT) is an established therapy for patients with relapsed lymphoma, but the role of positron emission tomography (PET) scanning preallogeneic and postallogeneic SCT is uncertain. We investigated whether pretransplantation PET status predicted outcome after allogeneic SCT and whether PET surveillance after transplantation provided additional information compared with computed tomography (CT) scanning. Eighty consecutive patients with lymphoma who received a reduced-intensity allogeneic SCT were entered onto a prospective trial. PET and CT scans were performed before transplantation and up to 36 months after transplantation. Forty-two patients were PET-positive before transplantation. Pretransplantation PET status had no significant impact on either relapse rate or overall survival. Thirty-four relapses were observed, of which 17 were PET-positive with a normal CT scan at relapse. Donor lymphocyte infusion (DLI) was administered in 26 episodes of relapse and was guided by PET alone in 14 patients. These findings suggest that, in contrast to autologous SCT, pretransplantation PET status is not predictive of relapse and survival after allogeneic SCT for lymphoma. Posttransplantation surveillance by PET detected relapse before CT in half of episodes, often allowing earlier administration of DLI in patients with recurrent lymphoma, and permitted withholding of potentially harmful DLI in those with PET-negative masses on CT scans.

Natural History of Epstein-Barr Virus Replication and Viral Load Dynamics after Alemtuzumab-Based Allogeneic Stem Cell Transplantation.

Epstein-Barr virus (EBV) load monitoring after allogeneic hematopoietic stem cell transplantation (HSCT) enables earlier detection of EBV replication and often serves as a trigger for preemptive therapies aimed at reducing EBV-related diseases. Our institutional strategy is to treat patients with clinical signs of EBV-related disease accompanied by a rising viral load, rather than to intervene based solely on viral load. This affords an opportunity to study the natural history of EBV replication and to assess whether our strategy reduces overtreatment without compromising outcomes. The objectives of the present study were to assess the natural history of untreated EBV replication in patients who underwent an alemtuzumab-based allogeneic HSCT and to examine whether our clinical strategy reduced overtreatment without compromising patient outcomes. In this retrospective single-center observational study of 515 consecutive patients (age ≥18 years) undergoing T cell-depleted allogeneic HSCT incorporating alemtuzumab, patients underwent surveillance monitoring for EBV by quantitative PCR in the peripheral blood at least weekly up to 100 days post-transplantation and longer if they remained on immunosuppressive therapy. The cumulative incidence of EBV detection and EBV-related disease were assessed. Among the 515 patients, 192 had EBV DNA detectable on ≥1 occasion, with a cumulative incidence of 35.8% (31.8% to 40.4%), although this remained below the limit of quantification in 93 patients. The median time to first detection was 89.5 days (range, 0 to 2254 days). The incidence was higher in recipients of sibling donor transplants (45.4% versus 30%; P = .00021) compared with recipients of unrelated donor transplants. Twenty patients developed EBV-related disease (cumulative incidence, 3.9%). Two patients had immunosuppression reduction alone, 18 received rituximab, and 5 required additional therapies. Five patients died from post-transplantation lymphoproliferative disorder, all of whom had received rituximab. The positive predictive value of EBV load for disease was higher in the unrelated donor cohort but remained <75% regardless of EBV threshold (57.1% to 72.7%). The cumulative incidence of EBV-related disease in our study (3.9%) is comparable to that reported in other studies incorporating alemtuzumab, and our clinical strategy reduced overtreatment in this patient population. PCR-based surveillance strategies have limitations, as reflected in the relatively low sensitivity of the assay coupled with the low positive predictive value, which may influence the potential choice of a threshold for preemptive intervention. We conclude that it remains unclear whether treatment based on a rising EBV viral load alone provides superior overall results to treatment based on the development of clinical signs of EBV-related disease in the context of a rising viral load.