NEW ORLEANS, La.—New findings on patients who have undergone allogeneic stem cell transplant (SCT) suggest a humoral response may be reached following the regularly approved SARS-CoV-2 vaccination schedule, particularly for patients who were free from immunosuppressive medications and immune reconstitution.

The results of a retrospective study showed that only 3% of patients had a reactivation of acute graft vs host disease (GcHD) following 2 vaccine doses, suggesting the vaccines were well tolerated, reported Marie Luise Hütter-Krönke, MD, of Charité-Universitätsmedizin in Berlin.

The findings were presented here at the 64th ASH Annual Meeting and Exposition.

“Patients after allogeneic stem cell transplantation are still at a higher risk for developing severe courses of severe acute respiratory syndrome (SARS-CoV2) or failing to eliminate the virus,” Dr. Hütter-Krönke said.

Vaccination against SARS-CoV-2 with mRNA and adenovirus vector-based vaccines is strongly recommended after allogeneic SCT for patients aged at least 3 months in the absence of acute GvHD, but data on response to vaccination within large representative cohorts of these patients are scarce, she noted.

They specifically assessed efficacy and safety following 2 and 3 SARS-CoV-2 vaccinations.

Hence, the researchers assessed 243 allogeneic SCT recipients who received SARS-CoV-2 vaccination, at medical centers in Berlin and Ulm, Germany, between March 2021 and January 2022. They specifically assessed efficacy and safety following second and third SARS-CoV-2 vaccinations.

Mean age was 59 years, and females accounted for 44% of the study group. Most of the cohort had lymphatic malignancies (23%) and myeloid disease (75%).

Following two doses of a vector-based or mRNA vaccine, participants were assessed for the anti-S-IgG protein and SARS-CoV2-spike protein. They were given an additional dose and assessed for anti-S-IgG. The researchers then did a multivariable analysis.

Matched-related donors accounted for 22% of transplantations, unrelated donors made up 76%, and haploidentical donors constituted 2%. Myeloablative conditioning regime was used in 46% of the cases and reduced intensity conditioning in 53%.

Only 2% of the cohort received mRNA-1273, 83% had 2 doses of BNT162b2, and 10% received ChAdOx1-S. Only 5% of the cohort got mixed vaccination, primarily ChAdOx1-S then an mRNA vaccine, and 1 patient received the JNJ-78436735 vaccine.

After 2 vaccinations, only 72% of the cohort demonstrated a humoral response. There were no related grade 3 or 4 toxicities.

These data demonstrated a lack of immune reconstitution (CD4-T-cell counts <200/µl), (OR=0.23, P< 0.001), ongoing immunosuppressive therapy (OR=0.45, P= 0.029), and age at the time of transplantation (OR=0.96, P=0.0065) were linked with no response following 2 vaccines doses. Immune reconstitution was the most pronounced factor for no response.

The use of sex and the intensity of conditioning in the arranging regimen demonstrated no effect on the development of a humoral response following vaccination.

The investigators also assessed the role of the interval between vaccination and transplantation, considering 6-month, 12-month, and 18-month time points. There was no strong relationship between the prospect of getting a specific immune response against SARS-CoV-2 and the time following transplantation after adjustment for prognostic factors.

Reference

Hütter-Krönke ML, Neagoie A, Blau IW, et al. Risk factors influencing humoral response to COVID 19 vaccination after allogeneic stem cell transplantation. Poster presented at: 64th ASH Annual Meeting and Exposition; December 10-13, 2022. New Orleans, Louisiana.