Eltrombopag improves platelet engraftment after haploidentical bone marrow transplantation: Results of a Phase II study

Slow platelet recovery frequently occurs after haploidentical hematopoietic stem cell transplantation (haplo-HSCT) with bone marrow graft and post-transplant cyclophosphamide (PCy)-based graft-versus-host disease (GVHD) prophylaxis. Improved platelet recovery may reduce the need for transfusions and improve outcomes. We investigated the safety and efficacy of eltrombopag, a thrombopoietin receptor agonist, at enhancing platelet recovery post-haplo-HSCT. The prospective study included patients ≥18 years of age who received haplo-HSCT with bone marrow graft and PCy. Patients received eltrombopag 300 mg/day starting on Day +5. The primary objective was to estimate platelet engraftment (>50 000/μL by Day 60). In a post hoc analysis, they were compared to a contemporary matched control group who did not receive eltrombopag. One hundred ten patients were included in the analysis (30 eltrombopag and 80 control). Seventy-three percent and 50% of patients in the eltrombopag group and control group, respectively, attained >50 000/μL platelet count by Day 60 (p = .043). No eltrombopag-related grade ≥4 adverse events were observed. Median time to platelet recovery (>20 000/μL) was 29 days with eltrombopag and 31 days for controls (p = .022), while its cumulative incidence was 90% (95% confidence interval [CI]: 78%-100%) with eltrombopag versus 67.5% (95% CI: 57%-78%) for controls (p = .014). Number of platelet transfusions received, overall survival, progression-free survival, GVHD rate, relapse rate, and non-relapse mortality were similar between groups. Overall, eltrombopag is safe and improves platelet recovery in patients undergoing haplo-HSCT with bone marrow graft and PCy.

Efficient neutralization of daratumumab in pretransfusion samples using a novel recombinant monoclonal anti-idiotype antibody

BACKGROUND

Anti-CD38 antibodies such as daratumumab (DARA) are critical therapies for multiple myeloma and other diseases. Unfortunately, anti-CD38 antibodies cause panreactivity in indirect antiglobulin tests (IATs), complicating blood compatibility testing. The anti-CD38 interference is most often mitigated by treating reagent red blood cells (RBCs) with dithiothreitol (DTT). However, when using the DTT method, not all RBC antibody specificities can be detected (e.g., anti-K), and the DTT method is impractical for some transfusion services. We evaluated the ability of a new anti-idiotype antibody to neutralize DARA in vitro and eliminate the anti-CD38 interference.

STUDY DESIGN AND METHODS

A recombinant monoclonal rabbit anti-DARA idiotype antibody ("anti-DARA") was generated. The ratio of anti-DARA required to neutralize DARA in spiked samples was evaluated in IATs performed in gel. IATs performed in tube were used to demonstrate that anti-DARA allows alloantibody detection in the presence of DARA. Plasma samples from 29 patients receiving DARA were treated with a fixed quantity of anti-DARA (120 μg) before performing antibody detection tests (screens) in tube.

RESULTS

Anti-DARA used at or above a 1:1 ratio with DARA eliminated the DARA interference with IATs. Anti-DARA allowed detection of both alloanti-E and alloanti-K in the presence of DARA. In 27/29 (93.1%) clinical samples, 120 μg anti-DARA was sufficient to neutralize the DARA in 100 μl patient plasma.

DISCUSSION

An anti-DARA:DARA ratio as low as 1:1 is sufficient to neutralize DARA in solution. A fixed amount of anti-DARA eliminates the anti-CD38 interference in most patient samples.

Freeze-dried platelets are a promising alternative in bleeding thrombocytopenic patients with hematological malignancies

Thrombosomes are trehalose-stabilized, freeze-dried group O platelets with a 3-year shelf life. They can be stockpiled, rapidly reconstituted, and infused regardless of the recipient's blood type. Thrombosomes thus represent a potential alternative platelet transfusion strategy. The present study assessed the safety and potential early signals of efficacy of Thrombosomes in bleeding thrombocytopenic patients. We performed an open-label, phase 1 study of single doses of allogeneic Thrombosomes at three dose levels in three cohorts, each consisting of eight patients who had hematologic malignancies, thrombocytopenia, and bleeding. Adverse events, dose-limiting toxicities (DLTs), World Health Organization (WHO) bleeding scores, and hematology values were assessed. No DLTs were reported. The median age was 59 years (24-71). Most patients had AML (58%) or ALL (29%), followed by MDS (8%) and myeloproliferative neoplasm (4%). The WHO scores of 22 patients who were actively bleeding at a total of 27 sites at baseline either improved (n = 17 [63%]) or stabilized (n = 10 [37%]) through day 6. Twenty-four hours after infusion, 12 patients (50%) had a clinically significant platelet count increase. Of eight patients who received no platelet transfusions for 6 days after Thrombosomes infusion, 5 had a clinically significant increase in platelet count of ≥5000 platelets/μL and 2 had platelet count normalization. Thrombosomes doses up to 3.78 × 10⁸ particles/kg demonstrated safety in 24 bleeding, thrombocytopenic patients with hematological malignancies. Thrombosomes may represent an alternative to conventional platelets to treat bleeding. A phase 2 clinical trial in a similar patient population is underway.

Generation of glucocorticoid-resistant SARS-CoV-2 T cells for adoptive cell therapy

Adoptive cell therapy with virus-specific T cells has been used successfully to treat life-threatening viral infections, supporting application of this approach to coronavirus disease 2019 (COVID-19). We expand severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) T cells from the peripheral blood of COVID-19-recovered donors and non-exposed controls using different culture conditions. We observe that the choice of cytokines modulates the expansion, phenotype, and hierarchy of antigenic recognition by SARS-CoV-2 T cells. Culture with interleukin (IL)-2/4/7, but not under other cytokine-driven conditions, results in more than 1,000-fold expansion in SARS-CoV-2 T cells with a retained phenotype, function, and hierarchy of antigenic recognition compared with baseline (pre-expansion) samples. Expanded cytotoxic T lymphocytes (CTLs) are directed against structural SARS-CoV-2 proteins, including the receptor-binding domain of Spike. SARS-CoV-2 T cells cannot be expanded efficiently from the peripheral blood of non-exposed controls. Because corticosteroids are used for management of severe COVID-19, we propose an efficient strategy to inactivate the glucocorticoid receptor gene (NR3C1) in SARS-CoV-2 CTLs using CRISPR-Cas9 gene editing.

Generation of glucocorticoid resistant SARS-CoV-2 T-cells for adoptive cell therapy

Adoptive cell therapy with viral-specific T cells has been successfully used to treat life-threatening viral infections, supporting the application of this approach against COVID-19. We expanded SARS-CoV-2 T-cells from the peripheral blood of COVID-19-recovered donors and non-exposed controls using different culture conditions. We observed that the choice of cytokines modulates the expansion, phenotype and hierarchy of antigenic recognition by SARS-CoV-2 T-cells. Culture with IL-2/4/7 but not other cytokine-driven conditions resulted in >1000 fold expansion in SARS-CoV-2 T-cells with a retained phenotype, function and hierarchy of antigenic recognition when compared to baseline (pre-expansion) samples. Expanded CTLs were directed against structural SARS-CoV-2 proteins, including the receptor-binding domain of Spike. SARS-CoV-2 T-cells could not be efficiently expanded from the peripheral blood of non-exposed controls. Since corticosteroids are used for the management of severe COVID-19, we developed an efficient strategy to inactivate the glucocorticoid receptor gene ( NR3C1 ) in SARS-CoV-2 CTLs using CRISPR-Cas9 gene editing.

Approaching treatment of transplant-associated thrombotic Microangiopathy from two directions with Eculizumab and transitioning from Tacrolimus to Sirolimus

BACKGROUND

In the past, conventional treatment strategies for transplant-associated thrombotic microangiopathy (TA-TMA) have not proven to be very effective. Recently, eculizumab which is a humanized monoclonal antibody that works as a terminal complement inhibitor has demonstrated promise in the treatment landscape of TA-TMA.

METHODS AND MATERIALS

This was a single-center retrospective analysis of 20 consecutive adult patients with TA-TMA: 10 patients who received conventional therapy and 10 patients who received eculizumab-based therapy. These patients had undergone allogeneic HSCT at MD Anderson Cancer Center between August 2011 and September 2016.

RESULTS

When comparing the treatment outcomes in the two cohorts, none of the patients in the conventional therapy group obtained a hematologic or complete response according to our response criteria whereas seven patients in the eculizumab group achieved a hematologic response with one patient achieving a complete response with organ recovery. In addition, overall survival at the end of assessment was 60% in the eculizumab cohort and 30% in the conventional cohort. One major difference in practice at our institution versus previously published studies is the management of immunosuppression. In a majority of patients, tacrolimus was continued or transitioned to sirolimus for GVHD prophylaxis.

CONCLUSION

Response rates and survival were improved for patients who were transitioned to sirolimus, so a two-pronged approach of inhibiting complement along with providing an alternative effective immunosuppressive agent may be beneficial in the treatment of early onset TA-TMA.

Unrecognized fluid overload during induction therapy increases morbidity in patients with acute promyelocytic leukemia

BACKGROUND

The combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has proven to be the most effective therapy for patients with acute promyelocytic leukemia (APL). The majority of the morbidity and mortality from APL therapy occur during the induction phase. The objective of the current study was to identify the risk factors associated with transfer to the intensive care unit (ICU) and endotracheal intubation during induction therapy in patients with APL.

METHODS

The authors analyzed the clinical characteristics of 187 patients with newly diagnosed APL who were treated with ATRA and ATO with or without gemtuzumab ozogamicin. The authors documented the percentage change in body weight from baseline to the maximum recorded weight during induction or to the day of ICU transfer.

RESULTS

A total of 18 patients (10%) who initiated therapy with ATRA and ATO on a regular hospital floor required transfer to the ICU after a median of 12 days of induction therapy. The median volume of transfusions was 4350 mL (range, 60-30,750 mL). The volume of transfusions was the main factor associated with the risk of ICU transfer (odds ratio, 4.1; P < .001). Of the 18 patients transferred to the ICU, 10 patients (5%) required intubation. An increase in the total volume of transfusions, increase in weight ≥10% during induction therapy, and a plasma albumin level ≤3.2 g/dL at the time of diagnosis were found to be associated with an increased risk of endotracheal intubation.

CONCLUSIONS

Large volumes of blood product transfusions and unrecognized fluid overload during induction are associated with ICU transfer and endotracheal intubation in patients with APL. These can be prevented by limiting the amount of transfusions, careful monitoring for subtle signs of fluid overload, and early intervention with aggressive diuretic therapy.

Prognosis of patients with intermediate risk IPSS-R myelodysplastic syndrome indicates variable outcomes and need for models beyond IPSS-R

The International Prognostic Scoring System-Revised (IPSS-R) is one standard for myelodysplastic syndrome (MDS) risk stratification. It divides patients into five categories including an intermediate subset (IPSS-R int-risk). Outcomes and clinical interventions for patients with IPSS-R int-risk are not well defined. We performed an analysis of outcomes of this group of patients. Out of 3167 patients, a total of 298 were identified with IPSS-R int-risk MDS and retrospectively analyzed to assess characteristics affecting outcomes. Cox proportional hazard models for overall survival (OS) were performed to identify statistically significant clinical factors that influence survival. Age of 66 years or greater, peripheral blood blasts of 2% or more, and history of red blood cell (RBC) transfusion were significantly associated with inferior survival. Based on these features, MDS patients with IPSS-R int-risk were classified into two prognostic risk groups for analysis, an int-favorable group and an int-adverse group, and had significantly divergent outcomes. Sequential prognostication was validated using two independent datasets comprising over 700 IPSS-R int-risk patients. The difference in median survival between int-favorable and int-adverse patients was 3.7 years in the test cohort, and 1.8 and 2.0 years in the two validation cohorts. These results confirm significantly variable outcomes of patients with IPSS-R int-risk and need for different prognostic systems.

Eculizumab for transplant-associated thrombotic microangiopathy in adult allogeneic stem cell transplant recipients

OBJECTIVE

To evaluate response rates and survival in adults with transplant-associated thrombotic microangiopathy (TA-TMA) after allogeneic hematopoietic stem cell transplantation (HSCT) who were treated with eculizumab (ECU).

METHODS

Patients were identified retrospectively and data collected through HSCT and pharmacy databases.

RESULTS

Ten patients with TA-TMA after allogeneic HSCT were treated with ECU between 2013 and 2016. TA-TMA was diagnosed at a median of 93 days post-HSCT. Organ-specific injury was documented in all ten patients at time of TA-TMA diagnosis, the most common being renal dysfunction (90%). Acute GVHD (70%) and active infection (80%) were common at time of diagnosis. The median time to ECU initiation from TA-TMA diagnosis was 4 days. Seven patients received ECU as first-line therapy in combination with other treatment modalities, while three patients were treated with ECU as second-line therapy. ECU was well tolerated with the exception of one case of severe skin rash leading to discontinuation. ECU achieved an overall hematologic response rate of 70% and an overall survival rate of 60%. One patient achieved a complete response with corresponding organ recovery.

CONCLUSION

Early initiation of ECU may not alter the disease process enough to restore organ function, but it may prolong survival.

Complement-Binding Donor-Specific Anti-HLA Antibodies and Risk of Primary Graft Failure in Hematopoietic Stem Cell Transplantation

Detection of donor-specific anti-HLA antibodies (DSA) has been associated with graft rejection in all forms of transplantation. The mechanism by which DSA increase the risk of graft failure remains unclear. We hypothesized that complement-binding DSA are associated with engraftment failure in hematopoietic stem cell transplantation (HSCT) and analyzed 122 haploidentical transplant recipients tested prospectively for DSA. Retrospective analysis to detect C1q binding DSA (C1q+DSA) was performed on 22 allosensitized recipients. Twenty-two of 122 patients (18%) had DSA, 19 of which were women (86%). Seven patients with DSA (32%) rejected the graft. Median DSA level at transplant for patients who failed to engraft was 10,055 mean fluorescence intensity (MFI) versus 2065 MFI for those who engrafted (P = .007). Nine patients with DSA were C1q positive in the initial samples with median DSA levels of 15,279 MFI (range, 1554 to 28,615), compared with 7 C1q-negative patients with median DSA levels of 2471 MFI (range, 665 to 12,254) (P = .016). Of 9 patients who were C1q positive in the initial samples, 5 patients remained C1q positive at time of transplant (all with high DSA levels [median, 15,279; range, 6487 to 22,944]) and experienced engraftment failure, whereas 4 patients became C1q negative pretransplant and all engrafted the donor cells (P = .008). In conclusion, patients with high DSA levels (>5000 MFI) and complement-binding DSA antibodies (C1q positive) appear to be at much higher risk of primary graft failure. The presence of C1q+DSA should be assessed in allosensitized patients before HSCT. Reduction of C1q+DSA levels might prevent engraftment failure in HSCT.

Are changes in HLA Ags responsible for leukemia relapse after HLA-matched allogeneic hematopoietic SCT?

Loss of heterozygosity (LOH) has been shown to be associated with leukemia relapse after haploidentical transplantation. Whether such changes are an important cause of relapse after HLA-matched transplantation remains unclear. We retrospectively HLA-typed leukemic blasts for 71 patients with AML/myelodysplastic syndrome obtained from stored samples, and the results were compared with those obtained at diagnosis and/or before the transplant. No LOH or any other changes in HLA Ag were found in any of the samples tested post transplant as compared with pretransplant specimens. One patient had LOH in HLA class I Ag (HLA-A,-B and -C); however, these changes were present in the pretransplant sample indicating that they occurred before the transplant. We concluded that, in contrast with haploidentical transplantation, HLA loss does not have a major role as a mechanism of relapse after allogeneic transplantation with a closely HLA-matched donor.

Outcomes of patients with myeloid malignancies treated with allogeneic hematopoietic stem cell transplantation from matched unrelated donors compared with one human leukocyte antigen mismatched related donors using HLA typing at 10 loci

Most candidates for hematopoietic stem cell transplantation (HSCT) lack a human leukocyte antigen (HLA)-identical sibling donor. Some patients may have a related donor with whom they are mismatched at 1 antigen/allele. It is not known whether such a match is preferable to a matched unrelated donor (MUD). We evaluated the outcomes (survival, relapse, nonrelapse mortality [NRM]) of all 28 patients with a single HLA antigen/allele mismatch identified through high-resolution HLA typing at HLA-A, -B, -C, -DRB1, and -DQB1, and all 318 patients with myeloid malignancies who received transplants from a 10/10 MUD treated during the same period of time at a single institution. Overall, outcomes for patients treated from a 1-antigen/allele mismatch related donor were significantly worse than from a MUD, primarily because of increased NRM. Overall survival (OS) rates at 3 years for 1-antigen/allele mismatched related donor and MUD transplant recipients were 19% and 45% (P = .007), and NRM rates were 40% and 26% (P = .05), respectively. Patients with class I mismatches appeared to have poorer OS than did patients with class II mismatches. A higher incidence of graft rejection was identified in the mismatched related donor group (P = .02). These results indicate that transplant outcomes are better with a MUD than with a 1 antigen/allele-mismatched related donor.