Fetal Laryngoscopy and Endoscopic Tracheal Intubation to Avoid ex utero Intrapartum Treatment in the Management of Fetuses with Suspected Airway Obstruction.

INTRODUCTION: Large congenital neck tumors can cause neonatal death due to airway obstruction. The aim of this study was to report outcomes of the first cohort of fetuses with neck masses and suspected airway obstruction managed with fetal laryngoscopy (FL) and fetal endoscopic tracheal intubation (FETI) to secure fetal airways and avoid ex utero intrapartum treatment (EXIT) procedure. METHODS: A prospective observational cohort of consecutive fetuses with neck masses that were candidates for an EXIT procedure due to suspicion of laryngeal and/or tracheal occlusion on ultrasonographic (US) or magnetic resonance imaging (MRI) examination were recruited for FL in a tertiary referral center in Queretaro, Mexico. FETI was performed if the obstruction was confirmed by FL. Maternal and perinatal outcomes were evaluated. RESULTS: Between January 2012 and March 2023, 35 cases with neck masses were evaluated. Airway obstruction was suspected in 12/35 (34.3%), either by US in 10/35 (28.6%) or by fetal MRI in 2/35 (5.7%). In all cases, FL was successfully performed at the first attempt at a median gestational age (GA) of 36+5 (range, 33+5-39+6) weeks+days, with a median surgical time of 22.5 (12-35) min. In 4 cases, airway patency was confirmed during FL and an EXIT procedure was avoided. In 8/12 cases (66.7%), airway obstruction was confirmed during fetoscopy and FETI was successfully performed at a median GA of 36+3 (33+2-38+5) weeks+days, with a median surgical time of 25.0 (range, 12-45) min. No case required an EXIT procedure. All patients underwent conventional cesarean delivery with no maternal complications and all neonates were admitted to the neonatal intensive care unit with a correctly positioned endotracheal tube (ETT) immediately after delivery. Three neonatal deaths (37.5%) were reported due to postnatal unplanned extubation, failed ETT replacement, and tumoral bleeding. CONCLUSION: In fetuses with neck masses and suspected airway obstruction, FL and FETI are feasible and could replace EXIT procedures with good maternal and perinatal outcomes.

Management of Late Twin-to-Twin Transfusion Syndrome beyond 26 Weeks: Comparison between Fetoscopic Laser Therapy versus Traditional Management.

INTRODUCTION: A proportion of monochorionic diamniotic (MCDA) twin pregnancies complicated by twin-to-twin transfusion syndrome (TTTS) can present after 26 weeks of gestation. The aim of this study was to compare perinatal outcomes of late TTTS treated by fetoscopic laser coagulation versus traditional management with amniodrainage and/or emergency preterm cesarean delivery (CD). METHODS: Retrospective cohort from January 2012 to January 2023 of consecutive MCDA twin pregnancies complicated by TTTS after 26 weeks and evaluated in our referring centers. We analyzed perinatal outcomes of cases treated with fetoscopic laser surgery at our national referral fetal surgery center in Queretaro, Mexico, and compared them with those managed with traditional management (amniodrainage and/or emergency preterm CD). The primary outcome was survival at discharge and the secondary outcome was gestational age (GA) at birth. RESULTS: Among the study population, 46 TTTS cases were treated by fetoscopy at 27+6 (26+0-31+0) weeks+days and were compared with a group of 39 cases who underwent emergency preterm CD. In comparison to the group who underwent traditional management, the group treated by laser fetoscopy showed a significantly higher GA at birth (32+3 vs. 29+1 weeks+days, p < 0.001), lower frequency of preterm delivery below 37 weeks (91.3% vs. 100%, p = 0.06), 34 weeks (63.0% vs. 100%, p < 0.001), 32 weeks (50% vs. 74.4%, p = 0.02), or 30 weeks (28.3% vs. 53.8%, p = 0.01), and significantly higher perinatal survival (89.1% vs. 71.8%, p < 0.05 of at least one twin; and 65.2% vs. 38.5%, p = 0.01 of both twins, respectively). CONCLUSION: MCDA twins complicated with TTTS can be treated with fetoscopic laser surgery between 26 and 31 weeks of gestation, which is a feasible and safe option, and such cases are associated with a higher GA at birth and better perinatal survival than those managed with amniodrainage and/or emergency preterm CD.

Apheresis of Deceased Donors as a New Source of Mobilized Peripheral Blood Hematopoietic Stem Cells for Transplant Tolerance.

BACKGROUND: Solid organ transplantation is the therapy of choice for many patients with end-stage organ failure; however, recipients must remain on lifelong immunosuppression, leaving them susceptible to infections and cancer. The study of transplant tolerance to prolong graft survival in the absence of immunosuppression has been restricted to recipients of living donor allografts; however, deceased donors significantly outnumber living donors. Mobilization of hematopoietic stem cells (HSCs) from the bone marrow to peripheral blood (PB) could allow PB-HSCs to be used to induce tolerance in deceased donor kidney recipients; however, a major concern is the well-known concomitant mobilization of immune cells into the liver. METHODS: We mobilized HSCs to the PD using a protocol of 2 doses of granulocyte colony-stimulating factor and 1 dose of plerixafor, followed by the collection of mobilized cells via apheresis in 3 deceased donors. The physiological, laboratory, and radiographic parameters were monitored throughout the procedure. Longitudinal biopsies were performed to assess the potential for ectopic liver mobilization. RESULTS: The use of both agents led to the successful mobilization of peripheral blood CD34+ cells, demonstrating the potential for use in transplant tolerance protocols. Increased immune cell trafficking into the liver was not observed, and apheresis of mobilized cells resulted in a uniform decrease in all liver leukocyte subsets. CONCLUSIONS: HSCs can be mobilized and collected from the PB of brain-dead donors. This new approach may facilitate the dissemination of immune tolerance trials beyond living-donor kidney transplantation to deceased-donor transplantation, without sacrificing the transplantability of the liver.

Evaluation of clonal hematopoiesis in pediatric ADA-SCID gene therapy participants.

Autologous stem cell transplant with gene therapy (ASCT-GT) provides curative therapy while reducing pretransplant immune-suppressive conditioning and eliminating posttransplant immune suppression. Clonal hematopoiesis of indeterminate potential (CHIP)-associated mutations increase and telomere lengths (TLs) shorten with natural aging and DNA damaging processes. It is possible that, if CHIP is present before ASCT-GT or mutagenesis occurs after busulfan exposure, the hematopoietic stem cells carrying these somatic variants may survive the conditioning chemotherapy and have a selective reconstitution advantage, increasing the risk of hematologic malignancy and overall mortality. Seventy-four peripheral blood samples (ranging from baseline to 120 months after ASCT-GT) from 10 pediatric participants who underwent ASCT-GT for adenosine deaminase-deficient severe combined immune deficiency (ADA-SCID) after reduced-intensity conditioning with busulfan and 16 healthy controls were analyzed for TL and CHIP. One participant had a significant decrease in TL. There were no CHIP-associated mutations identified by the next-generation sequencing in any of the ADA-SCID participants. This suggests that further studies are needed to determine the utility of germline analyses in revealing the underlying genetic risk of malignancy in participants who undergo gene therapy. Although these results are promising, larger scale studies are needed to corroborate the effect of ASCT-GT on TL and CHIP. This trial was registered at www.clinicaltrials.gov as #NCT00794508.

Long-term outcomes after gene therapy for adenosine deaminase severe combined immune deficiency.

Patients lacking functional adenosine deaminase activity have severe combined immunodeficiency (ADA SCID), which can be treated with ADA enzyme replacement therapy (ERT), allogeneic hematopoietic stem cell transplantation (HSCT), or autologous HSCT with gene-corrected cells (gene therapy [GT]). A cohort of 10 ADA SCID patients, aged 3 months to 15 years, underwent GT in a phase 2 clinical trial between 2009 and 2012. Autologous bone marrow CD34+ cells were transduced ex vivo with the MND (myeloproliferative sarcoma virus, negative control region deleted, dl587rev primer binding site)-ADA gammaretroviral vector (gRV) and infused following busulfan reduced-intensity conditioning. These patients were monitored in a long-term follow-up protocol over 8 to 11 years. Nine of 10 patients have sufficient immune reconstitution to protect against serious infections and have not needed to resume ERT or proceed to secondary allogeneic HSCT. ERT was restarted 6 months after GT in the oldest patient who had no evidence of benefit from GT. Four of 9 evaluable patients with the highest gene marking and B-cell numbers remain off immunoglobulin replacement therapy and responded to vaccines. There were broad ranges of responses in normalization of ADA enzyme activity and adenine metabolites in blood cells and levels of cellular and humoral immune reconstitution. Outcomes were generally better in younger patients and those receiving higher doses of gene-marked CD34+ cells. No patient experienced a leukoproliferative event after GT, despite persisting prominent clones with vector integrations adjacent to proto-oncogenes. These long-term findings demonstrate enduring efficacy of GT for ADA SCID but also highlight risks of genotoxicity with gRVs. This trial was registered at www.clinicaltrials.gov as #NCT00794508.

Autologous Ex Vivo Lentiviral Gene Therapy for Adenosine Deaminase Deficiency.

BACKGROUND: Severe combined immunodeficiency due to adenosine deaminase (ADA) deficiency (ADA-SCID) is a rare and life-threatening primary immunodeficiency. METHODS: We treated 50 patients with ADA-SCID (30 in the United States and 20 in the United Kingdom) with an investigational gene therapy composed of autologous CD34+ hematopoietic stem and progenitor cells (HSPCs) transduced ex vivo with a self-inactivating lentiviral vector encoding human ADA. Data from the two U.S. studies (in which fresh and cryopreserved formulations were used) at 24 months of follow-up were analyzed alongside data from the U.K. study (in which a fresh formulation was used) at 36 months of follow-up. RESULTS: Overall survival was 100% in all studies up to 24 and 36 months. Event-free survival (in the absence of reinitiation of enzyme-replacement therapy or rescue allogeneic hematopoietic stem-cell transplantation) was 97% (U.S. studies) and 100% (U.K. study) at 12 months; 97% and 95%, respectively, at 24 months; and 95% (U.K. study) at 36 months. Engraftment of genetically modified HSPCs persisted in 29 of 30 patients in the U.S. studies and in 19 of 20 patients in the U.K. study. Patients had sustained metabolic detoxification and normalization of ADA activity levels. Immune reconstitution was robust, with 90% of the patients in the U.S. studies and 100% of those in the U.K. study discontinuing immunoglobulin-replacement therapy by 24 months and 36 months, respectively. No evidence of monoclonal expansion, leukoproliferative complications, or emergence of replication-competent lentivirus was noted, and no events of autoimmunity or graft-versus-host disease occurred. Most adverse events were of low grade. CONCLUSIONS: Treatment of ADA-SCID with ex vivo lentiviral HSPC gene therapy resulted in high overall and event-free survival with sustained ADA expression, metabolic correction, and functional immune reconstitution. (Funded by the National Institutes of Health and others; ClinicalTrials.gov numbers, NCT01852071, NCT02999984, and NCT01380990.).

Cytoreductive conditioning intensity predicts clonal diversity in ADA-SCID retroviral gene therapy patients.

Retroviral gene therapy has proved efficacious for multiple genetic diseases of the hematopoietic system, but roughly half of clinical gene therapy trial protocols using gammaretroviral vectors have reported leukemias in some of the patients treated. In dramatic contrast, 39 adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) patients have been treated with 4 distinct gammaretroviral vectors without oncogenic consequence. We investigated clonal dynamics and diversity in a cohort of 15 ADA-SCID children treated with gammaretroviral vectors and found clear evidence of genotoxicity, indicated by numerous common integration sites near proto-oncogenes and by increased abundance of clones with integrations near MECOM and LMO2 These clones showed stable behavior over multiple years and never expanded to the point of dominance or dysplasia. One patient developed a benign clonal dominance that could not be attributed to insertional mutagenesis and instead likely resulted from expansion of a transduced natural killer clone in response to chronic Epstein-Barr virus viremia. Clonal diversity and T-cell repertoire, measured by vector integration site sequencing and T-cell receptor ß-chain rearrangement sequencing, correlated significantly with the amount of busulfan preconditioning delivered to patients and to CD34+ cell dose. These data, in combination with results of other ADA-SCID gene therapy trials, suggest that disease background may be a crucial factor in leukemogenic potential of retroviral gene therapy and underscore the importance of cytoreductive conditioning in this type of gene therapy approach.

Clinical efficacy of gene-modified stem cells in adenosine deaminase-deficient immunodeficiency.

BACKGROUND: Autologous hematopoietic stem cell transplantation (HSCT) of gene-modified cells is an alternative to enzyme replacement therapy (ERT) and allogeneic HSCT that has shown clinical benefit for adenosine deaminase-deficient (ADA-deficient) SCID when combined with reduced intensity conditioning (RIC) and ERT cessation. Clinical safety and therapeutic efficacy were evaluated in a phase II study. METHODS: Ten subjects with confirmed ADA-deficient SCID and no available matched sibling or family donor were enrolled between 2009 and 2012 and received transplantation with autologous hematopoietic CD34+ cells that were modified with the human ADA cDNA (MND-ADA) γ-retroviral vector after conditioning with busulfan (90 mg/m2) and ERT cessation. Subjects were followed from 33 to 84 months at the time of data analysis. Safety of the procedure was assessed by recording the number of adverse events. Efficacy was assessed by measuring engraftment of gene-modified hematopoietic stem/progenitor cells, ADA gene expression, and immune reconstitution. RESULTS: With the exception of the oldest subject (15 years old at enrollment), all subjects remained off ERT with normalized peripheral blood mononuclear cell (PBMC) ADA activity, improved lymphocyte numbers, and normal proliferative responses to mitogens. Three of nine subjects were able to discontinue intravenous immunoglobulin replacement therapy. The MND-ADA vector was persistently detected in PBMCs (vector copy number [VCN] = 0.1-2.6) and granulocytes (VCN = 0.01-0.3) through the most recent visits at the time of this writing. No patient has developed a leukoproliferative disorder or other vector-related clinical complication since transplant. CONCLUSION: These results demonstrate clinical therapeutic efficacy from gene therapy for ADA-deficient SCID, with an excellent clinical safety profile. TRIAL REGISTRATION: ClinicalTrials.gov NCT00794508. FUNDING: Food and Drug Administration Office of Orphan Product Development award, RO1 FD003005; NHLBI awards, PO1 HL73104 and Z01 HG000122; UCLA Clinical and Translational Science Institute awards, UL1RR033176 and UL1TR000124.