JAK2 V617F allele burden in polycythemia vera: burden of proof.

Polycythemia vera (PV) is a hematopoietic stem cell neoplasm defined by activating somatic mutations in the JAK2 gene and characterized clinically by overproduction of red blood cells, platelets, and neutrophils; a significant burden of disease-specific symptoms; high rates of vascular events; and evolution to a myelofibrosis phase or acute leukemia. The JAK2V617F variant allele frequency (VAF) is a key determinant of outcomes in PV, including thrombosis and myelofibrotic progression. Here, we critically review the dynamic role of JAK2V617F mutation burden in the pathogenesis and natural history of PV, the suitability of JAK2V617F VAF as a diagnostic and prognostic biomarker, and the utility of JAK2V617F VAF reduction in PV treatment.

Post hoc analysis of daratumumab plus lenalidomide, bortezomib and dexamethasone in Black patients from final data of the GRIFFIN study.

Due in part to racial disparities and underrepresentation in clinical studies, optimal therapies for Black patients with multiple myeloma remain undefined. This final analysis of GRIFFIN by race showed that the addition of daratumumab (D) to lenalidomide/bortezomib/dexamethasone (RVd) provides clinical benefit among both Black and White transplant-eligible newly diagnosed patients compared with RVd alone. However, Black patients were more likely to discontinue ≥1 drug due to treatment-emergent adverse events. In summary, these findings suggest a benefit of D-RVd front-line therapy among Black and White patients and underscore the importance of equitable treatment access for all patients.

Prophylactic tranexamic acid in patients with hematologic malignancy: a placebo-controlled, randomized clinical trial.

Evidence of the effectiveness of prophylactic use of tranexamic acid (TXA) in thrombocytopenia is lacking. To determine whether TXA safely reduces bleeding incidence in patients undergoing treatment for hematologic malignancies, a randomized, double-blind clinical trial was conducted from June 2016 through June 2020. Of 3120 screened adults, 356 patients were eligible and enrolled, and 337 patients (mean age, 53.9; 141 [41.8%] women), randomized to 1300 mg TXA orally or 1000 mg TXA through IV (n = 168) vs placebo (n = 169) thrice daily for maximum 30 days. Three hundred thirty patients were activated when their platelet counts fell below 30 000 per µL; 279 (83%) had complete outcome ascertainment. World Health Organization (WHO) grade ≥2 bleeding was observed in the 30 days following activation in 50.3% (73/145) and 54.2% (78/144) of patients in the TXA and placebo groups, with an adjusted odds ratio of 0.83 (95% confidence interval [CI], 0.50-1.34; P = .44). There was no statistically significant difference in the mean number of platelet transfusions (mean difference, 0.1; 95% CI, -1.9 to 2.0), mean days alive without grade ≥2 bleeding (mean difference, 0.8; 95% CI, -0.4 to 2.0), thrombotic events (6/163 [3.7%] TXA, 9/163 [5.5%] placebo), or deaths due to serious bleeding. Most common adverse events were: diarrhea (116/164 [70.7%] TXA and 114/163 [69.9%] placebo); febrile neutropenia (111/164 [67.7%] TXA, 105/163 [64.4%] placebo); fatigue (106/164 [64.6%] TXA, 109/163 [66.9%] placebo); and nausea (104/164 [63.4%] TXA, 97/163 [59.5%] placebo). Among patients with hematologic malignancy undergoing chemotherapy or hematopoietic stem cell transplantation, prophylactic treatment with TXA compared with placebo did not significantly reduce the risk of WHO grade ≥2 bleeding.

Health-related quality of life in transplant-eligible patients with newly diagnosed multiple myeloma treated with daratumumab, lenalidomide, bortezomib, and dexamethasone: Patient-reported outcomes from GRIFFIN.

In the phase 2 GRIFFIN trial (ClinicalTrials.gov identifier: NCT02874742), daratumumab added to lenalidomide, bortezomib, and dexamethasone (D-RVd) improved depth of response and progression-free survival (PFS) versus lenalidomide, bortezomib, and dexamethasone (RVd) alone in transplant-eligible (TE) patients with newly diagnosed multiple myeloma (NDMM). Here, we present patient-reported outcomes (PROs) collected using the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30-item (QLQ-C30), EORTC Quality of Life Questionnaire Multiple Myeloma Module 20-item (QLQ-MY20), and EuroQol 5-Dimension 5-Level (EQ-5D-5L) tools on day 1 of cycles 1, 2, and 3; on day 21 of cycle 4 (end of induction therapy); on day 1 of cycle 5; on day 21 of cycle 6 (end of posttransplant consolidation therapy); and at months 6, 12, 18, and 24 of maintenance therapy. Meaningful improvements from baseline were seen in most of the PRO scales with both treatments after consolidation and were sustained for at least 2 years of maintenance treatment. Large reductions from baseline (~20 points) were especially observed in pain symptoms for both treatment groups, although these were numerically higher for patients receiving D-RVd during the majority of the time points. In addition, improvements in key scales, such as global health status, fatigue symptoms, and physical functioning, were also seen with both D-RVd and RVd. These improvements in health-related quality of life contribute to the totality of evidence supporting the improvement in clinical outcomes such as response rates and PFS with D-RVd in induction, consolidation, and maintenance therapy in TE patients with NDMM.

Phase I study of opaganib, an oral sphingosine kinase 2-specific inhibitor, in relapsed and/or refractory multiple myeloma.

Multiple myeloma (MM) remains an incurable disease and there is an unmet medical need for novel therapeutic drugs that do not share similar mechanisms of action with currently available agents. Sphingosine kinase 2 (SK2) is an innovative molecular target for anticancer therapy. We previously reported that treatment with SK2 inhibitor opaganib inhibited myeloma tumor growth in vitro and in vivo in a mouse xenograft model. In the current study, we performed a phase I study of opaganib in patients with relapsed/refractory multiple myeloma (RRMM). Thirteen patients with RRMM previously treated with immunomodulatory agents and proteasome inhibitors were enrolled and treated with single-agent opaganib at three oral dosing regimens (250 mg BID, 500 mg BID, or 750 mg BID, 28 days as a cycle). Safety and maximal tolerated dose (MTD) were determined. Pharmacokinetics, pharmacodynamics, and correlative studies were also performed. Opaganib was well tolerated up to a dose of 750 mg BID. The most common possibly related adverse event (AE) was decreased neutrophil counts. There were no serious AEs considered to be related to opaganib. MTD was determined as at least 750 mg BID. On an intent-to-treat basis, one patient (7.7%) in the 500 mg BID dose cohort showed a very good partial response, and one other patient (7.7%) achieved stable disease for 3 months. SK2 is an innovative molecular target for antimyeloma therapy. The first-in-class SK2 inhibitor opaganib is generally safe for administration to RRMM patients, and has potential therapeutic activity in these patients. Clinicaltrials.gov: NCT02757326.

Daratumumab plus lenalidomide, bortezomib and dexamethasone in newly diagnosed multiple myeloma: Analysis of vascular thrombotic events in the GRIFFIN study.

Patients with multiple myeloma are at increased risk of vascular thromboembolic events (VTEs). This post hoc analysis evaluated VTEs in the randomised phase 2 GRIFFIN study (ClinicalTrials.gov Identifier: NCT02874742) that investigated lenalidomide/bortezomib/dexamethasone (RVd) ± daratumumab (D). Patients with newly diagnosed multiple myeloma who were eligible for autologous stem cell transplantation (ASCT) received D-RVd/RVd induction, high-dose therapy and ASCT, D-RVd/RVd consolidation and up to 2 years of lenalidomide maintenance therapy ± D. VTE prophylaxis was recommended (at least aspirin, ≥162 mg daily) in accordance with International Myeloma Working Group guidelines. In the safety population (D-RVd, n = 99; RVd, n = 102), VTEs occurred in 10.1% of D-RVd patients and 15.7% of RVd patients; grade 2-4 VTEs occurred in 9.1% and 14.7%, respectively. Median time to the first onset of VTE was longer for D-RVd versus RVd patients (305 days vs 119 days). Anti-thrombosis prophylaxis use was similar between arms (D-RVd, 84.8% vs RVd, 83.3%); among patients with VTEs, prophylaxis use at time of first VTE onset was 60.0% for D-RVd and 68.8% for RVd. In summary, the addition of daratumumab to RVd did not increase the incidence of VTEs, but the cumulative VTE incidence was relatively high in this cohort and anti-thrombotic prophylaxis use was suboptimal.

Daratumumab, lenalidomide, bortezomib, and dexamethasone for transplant-eligible newly diagnosed multiple myeloma: the GRIFFIN trial.

Lenalidomide, bortezomib, and dexamethasone (RVd) followed by autologous stem cell transplantation (ASCT) is standard frontline therapy for transplant-eligible patients with newly diagnosed multiple myeloma (NDMM). The addition of daratumumab (D) to RVd (D-RVd) in transplant-eligible NDMM patients was evaluated. Patients (N = 207) were randomized 1:1 to D-RVd or RVd induction (4 cycles), ASCT, D-RVd or RVd consolidation (2 cycles), and lenalidomide or lenalidomide plus D maintenance (26 cycles). The primary end point, stringent complete response (sCR) rate by the end of post-ASCT consolidation, favored D-RVd vs RVd (42.4% vs 32.0%; odds ratio, 1.57; 95% confidence interval, 0.87-2.82; 1-sided P = .068) and met the prespecified 1-sided α of 0.10. With longer follow-up (median, 22.1 months), responses deepened; sCR rates improved for D-RVd vs RVd (62.6% vs 45.4%; P = .0177), as did minimal residual disease (MRD) negativity (10-5 threshold) rates in the intent-to-treat population (51.0% vs 20.4%; P < .0001). Four patients (3.8%) in the D-RVd group and 7 patients (6.8%) in the RVd group progressed; respective 24-month progression-free survival rates were 95.8% and 89.8%. Grade 3/4 hematologic adverse events were more common with D-RVd. More infections occurred with D-RVd, but grade 3/4 infection rates were similar. Median CD34+ cell yield was 8.2 × 106/kg for D-RVd and 9.4 × 106/kg for RVd, although plerixafor use was more common with D-RVd. Median times to neutrophil and platelet engraftment were comparable. Daratumumab with RVd induction and consolidation improved depth of response in patients with transplant-eligible NDMM, with no new safety concerns. This trial was registered at www.clinicaltrials.gov as #NCT02874742.

Cancer Therapy-Associated Thrombosis.

[Figure: see text].

A plain language summary of daratumumab plus lenalidomide/bortezomib/dexamethasone in transplant-eligible Black patients with newly diagnosed multiple myeloma in the GRIFFIN study.

WHAT IS THIS SUMMARY ABOUT?: This is a summary of a publication about Black participants of the GRIFFIN clinical study that was published in Blood Cancer Journal in April 2022. The GRIFFIN clinical study looked at the treatment combination of daratumumab plus a standard therapy for multiple myeloma (called RVd therapy, which stands for lenalidomide, bortezomib, and dexamethasone) in adult patients who had not been treated before for multiple myeloma and so were considered to have newly diagnosed multiply myeloma. Multiple myeloma is a blood cancer of plasma cells. Based on the participants' age, medical history, and indicators of good general health, the participants in the GRIFFIN study were also eligible to receive autologous stem cell transplant as part of their therapy. This summary describes results for the Black participants of the GRIFFIN clinical study who received daratumumab plus RVd therapy (called D-RVd) to see if D-RVd therapy is better than RVd therapy at reducing the amount of multiple myeloma cancer cells in a patient's body. WHY DID THE RESEARCHERS EVALUATE THE RESULTS FOR BLACK PATIENTS IN THE GRIFFIN STUDY?: Due to racial disparities leading to historically low representation of minority groups in clinical studies, optimal treatments are not defined for Black patients with newly diagnosed multiple myeloma. Since previously published results from the overall population in the GRIFFIN study indicated that D-RVd therapy was better than RVd therapy, the researchers wanted to determine if this was also the case among Black participants. WHAT WERE THE RESULTS?: Out of 207 participants in the GRIFFIN study, 15% (32 participants) were Black and 78% (161 participants) were White. In both Black and White participants, D-RVd therapy reduced the amount of myeloma cancer cells more than RVd therapy. Additionally, D-RVd and RVd therapy had similar safety results for Black and White participants. WHAT DO THE RESULTS MEAN?: This analysis of GRIFFIN by race shows that Black people benefit from the daratumumab-containing D-RVd therapy as much as White people. Additionally, D-RVd therapy had similar safety results to RVd therapy for both Black and White people. Clinical Trial Registration: NCT02874742 (ClinicalTrials.gov).

Thrombosis in myeloproliferative neoplasms: update in pathophysiology.

PURPOSE OF REVIEW: This review summarizes high-impact research in myeloproliferative neoplasms (MPN) from the last 18 months, with a particular focus on basic science findings. RECENT FINDINGS: A pseudo-hypoxia state with stabilization of hypoxia-inducible factor (HIFα exists that is central to cell growth, cell renewal, inflammation, and thrombotic potential in MPN hematopoietic cells. SUMMARY: HIFα and inflammatory pathways are new therapeutic targets in MPN, with the potential to ameliorate thrombotic risk and perhaps eradicate mutant progenitor cells.

Melflufen plus dexamethasone in relapsed/refractory multiple myeloma: long-term survival follow-up from the Phase II study O-12-M1.

An updated survival analysis was conducted for the Phase II study O-12-M1 of melphalan flufenamide (melflufen) plus dexamethasone in patients with relapsed/refractory multiple myeloma (RRMM) with two or more prior lines of therapy (including bortezomib and lenalidomide). Partial response or better was seen in 31%. After a 46-month median overall survival (OS) follow-up, melflufen plus dexamethasone had a median OS of 20·7 months (75th percentile OS, 47·5 months). The median time-to-next treatment for melflufen plus dexamethasone was 7·9 months. In summary, melflufen plus dexamethasone resulted in sustained long-term clinical benefit in patients with RRMM.

Neutrophils: back in the thrombosis spotlight.

Reactive and clonal neutrophil expansion has been associated with thrombosis, suggesting that neutrophils play a role in this process. However, although there is no doubt that activated monocytes trigger coagulation in a tissue factor-dependent manner, it remains uncertain whether stimulated neutrophils can also directly activate coagulation. After more than a decade of debate, it is now largely accepted that normal human neutrophils do not synthetize tissue factor, the initiator of the extrinsic pathway of coagulation. However, neutrophils may passively acquire tissue factor from monocytes. Recently, the contact system, which initiates coagulation via the intrinsic pathway, has been implicated in the pathogenesis of thrombosis. After the recent description of neutrophil extracellular trap (NET) release by activated neutrophils, some animal models of thrombosis have demonstrated that coagulation may be enhanced by direct NET-dependent activation of the contact system. However, there is currently no consensus on how to assess or quantify NETosis in vivo, and other experimental animal models have failed to demonstrate a role for neutrophils in thrombogenesis. Nevertheless, it is likely that NETs can serve to localize other circulating coagulation components and can also promote vessel occlusion independent of fibrin formation. This article provides a critical appraisal of the possible roles of neutrophils in thrombosis and highlights some existing knowledge gaps regarding the procoagulant activities of neutrophil-derived extracellular chromatin and its molecular components. A better understanding of these mechanisms could guide future approaches to prevent and/or treat thrombosis.

A comparison of response in the presence or absence of a delay in induction therapy with bortezomib, lenalidomide, and dexamethasone.

PURPOSE: Lenalidomide, bortezomib, and dexamethasone (RVd) has emerged as a preferred induction therapy in multiple myeloma (MM) in the United States. Due to lenalidomide's teratogenic risk, patients and prescribers must comply with a risk evaluation and mitigation strategy (REMS) program. The REMS program limits dispensing to certain third-party specialty pharmacies, whose average prescription fill times are longer than in-house specialty pharmacies. In practice, a delay in procurement of lenalidomide may mean that patients start therapy with only bortezomib and dexamethasone, delaying the start of more effective triplet therapy. The primary objective of this study is to determine if a delay from start of bortezomib and dexamethasone to start of triplet therapy with lenalidomide impacts rate of achievement of very good partial response (VGPR) after four cycles of RVd. METHODS: This was a single-center retrospective review of adults with newly diagnosed MM who received RVd induction therapy at University of North Carolina Medical Center between April 2014 and June 2017. Patients who started lenalidomide ≥10 days after bortezomib comprised the "Delay" group, while those who started lenalidomide concurrently with bortezomib or within 1-9 days after bortezomib comprised the "No Delay" group. The primary outcome was VGPR or better response rate after four cycles of RVd. RESULTS: Thirty-eight patients met inclusion criteria. Nine patients (23.7%) experienced any delay in initiation of lenalidomide, with a mean delay of 7.8 days (range 1-18). Four patients (10.5%) experienced a delay ≥10 days. No patients in the Delay group were of reproductive potential, compared to 8.8% in the No Delay group (p = 0.54). VGPR or better response rate did not differ between the Delay and No Delay groups (66.7% vs. 58.8%, p = 0.79). The mean number of lenalidomide prescriptions generated per RVd cycle was 1.35 (range 1-5, SD 0.74). CONCLUSIONS: This study did not demonstrate an effect on clinical response after delays ≥10 days between bortezomib and lenalidomide initiation. No patients in the delay group were females of reproductive potential, which is the primary target for increased safety behind the REMS program.

Targeting B-cell maturation antigen with GSK2857916 antibody-drug conjugate in relapsed or refractory multiple myeloma (BMA117159): a dose escalation and expansion phase 1 trial.

BACKGROUND: B-cell maturation antigen (BCMA) is a cell-surface receptor of the tumour necrosis superfamily required for plasma cell survival. BMCA is universally detected on patient-derived myeloma cells and has emerged as a selective antigen to be targeted by novel treatments in multiple myeloma. We assessed the safety, tolerability, and preliminary clinical activity of GSK2857916, a novel anti-BCMA antibody conjugated to microtubule-disrupting agent monomethyl auristatin F, in patients with relapsed and refractory multiple myeloma. METHODS: We did an international, multicentre, open-label, first-in-human phase 1 study with dose escalation (part 1) and dose expansion (part 2) phases, at nine centres in the USA, Canada, and the UK. Adults with histologically or cytologically confirmed multiple myeloma, Eastern Cooperative Oncology Group performance status 0 or 1, and progressive disease after stem cell transplantation, alkylators, proteasome inhibitors, and immunomodulators were recruited for this study. In part 1, patients received GSK2857916 (0·03-4·60 mg/kg) through 1 h intravenous infusions once every 3 weeks. In part 2, patients received the selected recommended phase 2 dose of GSK2857916 (3·40 mg/kg) once every 3 weeks. Primary endpoints were maximum tolerated dose and recommended phase 2 dose. Secondary endpoints for part 2 included preliminary anti-cancer clinical activity. All patients who received one or more doses were included in this prespecified administrative interim analysis (data cutoff date June 26, 2017), which was done for internal purposes. This study is registered with ClinicalTrials.gov, number NCT02064387, and is ongoing, but closed for recruitment. FINDINGS: Between July 29, 2014, and Feb 21, 2017, we treated 73 patients: 38 patients in the dose-escalation part 1 and 35 patients in the dose-expansion part 2. There were no dose-limiting toxicities and no maximum tolerated dose was identified in part 1. On the basis of safety and clinical activity, we selected 3·40 mg/kg as the recommended phase 2 dose. Corneal events were common (20 [53%] of 38 patients in part 1 and 22 [63%] of 35 in part 2); most (18 [47%] in part 1 and 19 [54%] in part 2) were grade 1 or 2 and resulted in two treatment discontinuations in part 1 and no discontinuations in part 2. The most common grade 3 or 4 events were thrombocytopenia (13 [34%] of 38 patients in part 1 and 12 [34%] of 35 in part 2) and anaemia (6 [16%] in part 1 and 5 [14%] in part 2). There were 12 treatment-related serious adverse events and no treatment-related deaths. In part 2, 21 (60·0%; 95% CI 42·1-76·1) of 35 patients achieved an overall response. INTERPRETATION: At the identified recommended phase 2 dose, GSK2857916 was well tolerated and had good clinical activity in heavily pretreated patients, thereby indicating that this might be a promising candidate for the treatment of relapsed or refractory multiple myeloma. FUNDING: GlaxoSmithKline.

Daratumumab in transplant-eligible patients with newly diagnosed multiple myeloma: final analysis of clinically relevant subgroups in GRIFFIN.

The randomized, phase 2 GRIFFIN study (NCT02874742) evaluated daratumumab plus lenalidomide/bortezomib/dexamethasone (D-RVd) in transplant-eligible newly diagnosed multiple myeloma (NDMM). We present final post hoc analyses (median follow-up, 49.6 months) of clinically relevant subgroups, including patients with high-risk cytogenetic abnormalities (HRCAs) per revised definition (del[17p], t[4;14], t[14;16], t[14;20], and/or gain/amp[1q21]). Patients received 4 induction cycles (D-RVd/RVd), high-dose therapy/transplant, 2 consolidation cycles (D-RVd/RVd), and lenalidomide±daratumumab maintenance (≤ 2 years). Minimal residual disease-negativity (10-5) rates were higher for D-RVd versus RVd in patients ≥ 65 years (67.9% vs 17.9%), with HRCAs (54.8% vs 32.4%), and with gain/amp(1q21) (61.8% vs 28.6%). D-RVd showed a trend toward improved progression-free survival versus RVd (hazard ratio [95% confidence interval]) in patients ≥ 65 years (0.29 [0.06-1.48]), with HRCAs (0.38 [0.14-1.01]), and with gain/amp(1q21) (0.42 [0.14-1.27]). In the functional high-risk subgroup (not MRD negative at the end of consolidation), the hazard ratio was 0.82 (0.35-1.89). Among patients ≥ 65 years, grade 3/4 treatment-emergent adverse event (TEAE) rates were higher for D-RVd versus RVd (88.9% vs 77.8%), as were TEAEs leading to discontinuation of ≥ 1 treatment component (37.0% vs 25.9%). One D-RVd patient died due to an unrelated TEAE. These results support the addition of daratumumab to RVd in transplant-eligible patients with high-risk NDMM. Video Abstract.

Daratumumab-based quadruplet therapy for transplant-eligible newly diagnosed multiple myeloma with high cytogenetic risk.

In the MASTER study (NCT03224507), daratumumab+carfilzomib/lenalidomide/dexamethasone (D-KRd) demonstrated promising efficacy in transplant-eligible newly diagnosed multiple myeloma (NDMM). In GRIFFIN (NCT02874742), daratumumab+lenalidomide/bortezomib/dexamethasone (D-RVd) improved outcomes for transplant-eligible NDMM. Here, we present a post hoc analysis of patients with high-risk cytogenetic abnormalities (HRCAs; del[17p], t[4;14], t[14;16], t[14;20], or gain/amp[1q21]). Among 123 D-KRd patients, 43.1%, 37.4%, and 19.5% had 0, 1, or ≥2 HRCAs. Among 120 D-RVd patients, 55.8%, 28.3%, and 10.8% had 0, 1, or ≥2 HRCAs. Rates of complete response or better (best on study) for 0, 1, or ≥2 HRCAs were 90.6%, 89.1%, and 70.8% for D-KRd, and 90.9%, 78.8%, and 61.5% for D-RVd. At median follow-up (MASTER, 31.1 months; GRIFFIN, 49.6 months for randomized patients/59.5 months for safety run-in patients), MRD-negativity rates as assessed by next-generation sequencing (10-5) were 80.0%, 86.4%, and 83.3% for 0, 1, or ≥2 HRCAs for D-KRd, and 76.1%, 55.9%, and 61.5% for D-RVd. PFS was similar between studies and superior for 0 or 1 versus ≥2 HRCAs: 36-month PFS rates for D-KRd were 89.9%, 86.2%, and 52.4%, and 96.7%, 90.5%, and 53.5% for D-RVd. These data support the use of daratumumab-containing regimens for transplant-eligible NDMM with HCRAs; however, additional strategies are needed for ultra-high-risk disease (≥2 HRCAs). Video Abstract.

Tissue factor activates the coagulation cascade in mouse models of acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is associated with a high risk of bleeding and thrombosis. APL patients have an activated coagulation system, hyperfibrinolysis, and thrombocytopenia. APL cells express tissue factor (TF), a receptor and cofactor for factor VII/VIIa. This study had 2 goals. Firstly, we measured biomarkers of coagulation and fibrinolysis activation as well as platelet counts and bleeding in both mouse xenograft and allograft models of APL. Secondly, we determined the effect of inhibiting TF on the activation of coagulation in these models. We observed increased levels of plasma thrombin-antithrombin complexes (TAT), D-dimer, and plasmin-antiplasmin complexes, reduced platelet counts, and increased tail bleeding in both mouse models of APL. Fibrinogen levels decreased in the xenograft model but not in the allograft model. In contrast, the red blood cell count decreased in the allograft model but not in the xenograft model. Inhibition of APL-derived human TF with an anti-human TF monoclonal antibody reduced the level of TAT, increased platelet count, and normalized tail bleeding in a xenograft model. Inhibition of all sources of TF (APL cells and host cells) in the allograft model with a rat anti-mouse TF monoclonal antibody decreased the levels of TAT but did not affect the platelet count. Our study demonstrates that TF plays a central role in the activation of coagulation in both the xenograft and allograft mouse models of APL. These APL mouse models can be used to investigate the mechanisms of coagulopathy and thrombocytopenia in APL.

Stem Cell Mobilization Yields with Daratumumab- and Lenalidomide-Containing Quadruplet Induction Therapy in Newly Diagnosed Multiple Myeloma: Findings from the MASTER and GRIFFIN Trials.

For eligible patients with newly diagnosed multiple myeloma (NDMM), standard of care includes induction therapy followed by autologous stem cell transplantation (ASCT). Daratumumab as monotherapy and in combination treatment is approved across multiple lines of therapy for multiple myeloma (MM), and lenalidomide is an effective and commonly used agent for induction and maintenance therapy in MM. However, there is concern that lenalidomide and daratumumab given as induction therapy might impair mobilization of stem cells for ASCT. Therefore, we assessed stem cell mobilization in patients following frontline induction therapy in the MASTER and GRIFFIN phase 2 clinical studies by examining stem cell mobilization yields, apheresis attempts, and engraftment outcomes for patients from each study. Adult transplantation-eligible patients with NDMM received induction therapy consisting of daratumumab plus carfilzomib/lenalidomide/dexamethasone (D-KRd) for four 28-day cycles in the single-arm MASTER trial or lenalidomide/bortezomib/dexamethasone (RVd) with or without daratumumab (D) for four 21-day cycles in the randomized GRIFFIN trial, followed by stem cell mobilization and ASCT in both studies. Institutional practice differed regarding plerixafor use for stem cell mobilization; the strategies were upfront (ie, planned plerixafor use) or rescue (ie, plerixafor use only after mobilization parameters indicated failure with granulocyte colony-stimulating factor [G-CSF] alone). Descriptive analyses were used to summarize patient characteristics, stem cell mobilization yields, and engraftment outcomes. In MASTER, 116 D-KRd recipients underwent stem cell mobilization and collection at a median of 24 days after completing induction therapy. In GRIFFIN, 175 patients (D-RVd, n = 95; RVd, n = 80) underwent mobilization at a median of 27 days after completing D-RVd induction therapy and 24 days after completing RVd induction therapy. Among those who underwent mobilization and collection, 7% (8 of 116) of D-KRd recipients, 2% (2 of 95) of D-RVd recipients, and 6% (5 of 80) of RVd recipients did not meet the center-specific minimally required CD34+ cell yield in the first mobilization attempt; however, nearly all collected sufficient stem cells for ASCT on remobilization. Among patients who underwent mobilization, plerixafor use, either upfront or as a rescue strategy, was higher in patients receiving D-KRd (97%; 112 of 116) and D-RVd (72%; 68 of 95) compared with those receiving RVd (55%; 44 of 80). The median total CD34+ cell collection was 6.0 × 106/kg (range, 2.2 to 13.9 × 106/kg) after D-KRd induction, 8.3 × 106/kg (range, 2.6 to 33.0 × 106/kg) after D-RVd induction, and 9.4 × 106/kg (range, 4.1 to 28.7 × 106/kg) after RVd induction; the median days for collection were 2, 2, and 1, respectively. Among patients who underwent mobilization, 98% (114 of 116) of D-KRd patients, 99% (94 of 95) of D-RVd patients, and 98% (78 of 80) of RVd patients underwent ASCT using median CD34+ cell doses of 3.2 × 106/kg, 4.2 × 106/kg, and 4.8 × 106/kg, respectively. The median time to neutrophil recovery was 12 days in all 3 treatment groups across the 2 trials. Because both trials used different criteria to define platelet recovery, data on platelet engraftment using the same criteria are not available. Four cycles of daratumumab- and lenalidomide-based quadruplet induction therapy had a minimal impact on stem cell mobilization and allowed predictable stem cell harvesting and engraftment in all patients who underwent ASCT. Upfront plerixafor strategy may be considered, but many patients were successfully collected with the use of G-CSF alone or rescue plerixafor.