Favorable outcomes of COVID-19 in vaccinated hematopoietic stem cell transplant recipients: A single-center experience

INTRODUCTION

A high incidence of mortality and severe COVID-19 infection was reported in hematopoietic stem cell transplant (HSCT) recipients during the early phases of the COVID-19 pandemic; however, outcomes with subsequent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, such as the omicron variant, have yet to be reported. Additionally, rollout of COVID-19 vaccinations in subsequent pandemic waves may modify COVID-19 disease severity and mortality in this immunocompromised population. We describe COVID-19 outcomes among a highly vaccinated population of HSCT recipients at a single center during successive waves of community transmission arising from the SARS-CoV-2 delta and omicron variants.

METHODS

We retrospectively reviewed medical records of all HSCT recipients at our institution who tested positive for SARS-CoV-2 from May 2021 to May 2022. Descriptive statistics were reported; the chi-square test was utilized to identify factors associated with 90-day all-cause mortality and severity of COVID-19 infection.

RESULTS

Over the 1-year study period, 77 HSCT recipients at our center contracted COVID-19 (43 allogenic; 34 autologous). Twenty-six (33.8%) patients were infected with the SARS-CoV-2 delta variant, while 51 (66.2%) had the SARS-CoV-2 omicron variant. Thirty-nine (50.6%) patients required hospitalization. More than 80% had received prior COVID-19 vaccination (57.1% with two doses, 27.3% with three doses). The majority (90.9%) had mild disease; only one (1.3%) patient required mechanical ventilation. Active hematological disease at time of COVID-19 infection was associated with increased odds of mortality [odds ratio (OR) = 6.90, 95% confidence interval (CI) = 1.20-40]. The 90-day all-cause mortality was 7.8% (six patients). Infection with the omicron variant (vs. delta) was associated with less severe illness (OR = 0.05, 95% CI = 0.01-0.47) and decreased odds of mortality (OR = 0.08, 95% CI = 0.01-0.76). Being on immunosuppression (OR = 5.10, 95% CI = 1.10-23.60) and being unvaccinated at disease onset (OR = 14.76, 95% CI = 2.89-75.4) were associated with greater severity of COVID-19 infection.

CONCLUSION

We observed favorable outcomes with COVID-19 infection in a cohort of vaccinated HSCT patients. The SARS-CoV-2 omicron variant was associated with both less severe illness and decreased odds of mortality. As COVID-19 moves toward endemicity, early access to treatment and encouraging vaccination uptake is crucial in mitigating the challenge of COVID-19 management among HSCT recipients. Surveillance and assessment of clinical outcomes with new SARS-CoV-2 variants also remains important in this immunocompromised population.

Artificial Cell Membrane Polymersome-Based Intranasal Beta Spike Formulation as a Second Generation Covid-19 Vaccine

Current parenteral coronavirus disease 2019 (Covid-19) vaccines inadequately protect against infection of the upper respiratory tract. Additionally, antibodies generated by wild type (WT) spike-based vaccines poorly neutralize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. To address the need for a second-generation vaccine, we have initiated a preclinical program to produce and evaluate a potential candidate. Our vaccine consists of recombinant Beta spike protein coadministered with synthetic CpG adjuvant. Both components are encapsulated within artificial cell membrane (ACM) polymersomes, synthetic nanovesicles efficiently internalized by antigen presenting cells, including dendritic cells, enabling targeted delivery of cargo for enhanced immune responses. ACM vaccine is immunogenic in C57BL/6 mice and Golden Syrian hamsters, evoking high serum IgG and neutralizing responses. Compared to an ACM-WT spike vaccine that generates predominantly WT-neutralizing antibodies, the ACM-Beta spike vaccine induces antibodies that neutralize WT and Beta viruses equally. Intramuscular (IM)-immunized hamsters are strongly protected from weight loss and other clinical symptoms after the Beta challenge but show delayed viral clearance in the upper airway. With intranasal (IN) immunization, however, neutralizing antibodies are generated in the upper airway concomitant with rapid and potent reduction of viral load. Moreover, antibodies are cross-neutralizing and show good activity against Omicron. Safety is evaluated in New Zealand white rabbits in a repeated dose toxicological study under Good Laboratory Practice (GLP) conditions. Three doses, IM or IN, at two-week intervals do not induce an adverse effect or systemic toxicity. Cumulatively, these results support the application for a Phase 1 clinical trial of ACM-polymersome-based Covid-19 vaccine (ClinicalTrials.gov identifier: NCT05385991).

HEMATOPOIETIC STEM CELL TRANSPLANT IN AGGRESSIVE T AND NK/T CELL LYMPHOMA - ROLE OF UPFRONT AUTOLOGOUS TRANSPLANT IN NODAL PERIPHERAL T-CELL LYMPHOMA

Aggressive T and NK/T-cell lymphoma are known to have a high risk of relapse and poor long-term prognosis. Hematopoietic stem cell transplantation has been performed as part of consolidation or salvage treatment. We retrospectively studied the outcomes of autologous (A) and allogeneic (allo) hematopoietic stem cell transplantation (SCT) in aggressive T and NK/T-cell lymphoma at our center between 2010 to 2020. Patients with nodal peripheral T-cell lymphoma (PTCL) that were younger than 65 years old who did not receive upfront autologous SCT (ASCT) at first complete remission were selected from our registry data for further comparison. Thirty-six patients underwent ASCT, and 16 patients underwent alloSCT. In the ASCT cohort, 18 patients with nodal PTCL who underwent upfront ASCT at first complete remission (upfront ASCT) were compared with 15 patients with nodal PTCL who were in first complete remission after single-line induction but did not receive ASCT. The two-year progression-free survival (PFS) and overall survival (OS) rates for the ASCT cohort were 58% and 73%, respectively. The two-year PFS and OS for the alloSCT cohort were 47% (P=0.35, P=0.02, respectively). Twenty-four patients who received SCT at first remission (21 ASCT and three alloSCT) had a two-year PFS and OS of 75% and 89%, respectively. In comparison, 28 patients who received SCT at relapse/refractory (15 ASCT and 13 alloSCT) had a two-year PFS and OS of 40% and 50%, respectively (P=0.047, P=0.024, respectively). Patients in complete remission prior to transplantation (n=42) had a two-year PFS and OS of 59% and 73%, respectively. In contrast, patients in partial remission prior to transplantation (n=10) had a two-year PFS and OS of 40% and 48%, respectively (p>0.05). Non-relapse mortality occurred in 6% and 43% of ASCT and AlloSCT, respectively. Multivariate analysis revealed that EBV-positivity at diagnosis indicated poorer PFS. EBV-positivity at diagnosis and more than two prior lines of treatment at transplant were associated with poorer OS. For nodal PTCL, the two-year PFS and OS were 79% and 100% for the upfront ASCT cohort and 78% and 92% for the non-upfront ASCT cohort, respectively (p>0.05). Hematopoietic SCT is a feasible treatment option for aggressive T and NK/T-cell lymphoma. Patients who underwent SCT at first remission had better survival rates than those who underwent SCT at relapse/refractory. Nevertheless, due to the limited sample size of the current study, the role of upfront ASCT in patients with nodal PTCL who achieved first complete remission remains unclear.

Combining AFM13, a Bispecific CD30/CD16 Antibody, with Cytokine-Activated Blood and Cord Blood-Derived NK Cells Facilitates CAR-like Responses Against CD30+ Malignancies

PURPOSE

Natural killer (NK)-cell recognition and function against NK-resistant cancers remain substantial barriers to the broad application of NK-cell immunotherapy. Potential solutions include bispecific engagers that target NK-cell activity via an NK-activating receptor when simultaneously targeting a tumor-specific antigen, as well as enhancing functionality using IL12/15/18 cytokine pre-activation.

EXPERIMENTAL DESIGN

We assessed single-cell NK-cell responses stimulated by the tetravalent bispecific antibody AFM13 that binds CD30 on leukemia/lymphoma targets and CD16A on various types of NK cells using mass cytometry and cytotoxicity assays. The combination of AFM13 and IL12/15/18 pre-activation of blood and cord blood-derived NK cells was investigated in vitro and in vivo.

RESULTS

We found heterogeneity within AFM13-directed conventional blood NK cell (cNK) responses, as well as consistent AFM13-directed polyfunctional activation of mature NK cells across donors. NK-cell source also impacted the AFM13 response, with cNK cells from healthy donors exhibiting superior responses to those from patients with Hodgkin lymphoma. IL12/15/18-induced memory-like NK cells from peripheral blood exhibited enhanced killing of CD30+ lymphoma targets directed by AFM13, compared with cNK cells. Cord-blood NK cells preactivated with IL12/15/18 and ex vivo expanded with K562-based feeders also exhibited enhanced killing with AFM13 stimulation via upregulation of signaling pathways related to NK-cell effector function. AFM13-NK complex cells exhibited enhanced responses to CD30+ lymphomas in vitro and in vivo.

CONCLUSIONS

We identify AFM13 as a promising combination with cytokine-activated adult blood or cord-blood NK cells to treat CD30+ hematologic malignancies, warranting clinical trials with these novel combinations.