AVALON: The Italian cohort study on real-life efficacy of hypomethylating agents plus venetoclax in newly diagnosed or relapsed/refractory patients with acute myeloid leukemia.

BACKGROUND: Venetoclax in combination with hypomethylating agents (HMA) is revolutionizing the therapy of acute myeloid leukemia (AML). However, evidence on large sets of patients is lacking, especially in relapsed or refractory leukemia. METHODS: AVALON is a multicentric cohort study that was conducted in Italy on patients with AML who received venetoclax-based therapies from 2015 to 2020. The study was approved by the ethics committee of the participating institution and was conducted in accordance with the Declaration of Helsinki. The effectiveness and toxicity of venetoclax + HMA in 190 (43 newly diagnosed, 68 refractory, and 79 relapsed) patients with AML are reported here. RESULTS: In the newly diagnosed AML, the overall response rate and survival confirmed the brilliant results demonstrated in VIALE-A. In the relapsed or refractory AML, the combination demonstrated a surprisingly complete remission rate (44.1% in refractory and 39.7% in relapsed evaluable patients) and conferred to treated patients a good expectation of survival. Toxicities were overall manageable, and most incidents occurred in the first 60 days of therapy. Infections were confirmed as the most common nonhematologic adverse event. CONCLUSIONS: Real-life data show that the combination of venetoclax and HMA offers an expectation of remission and long-term survival to elderly, newly diagnosed patients, and to relapsed or chemoresistant AML, increasing the chance of cure through a different mechanism of action. The venetoclax + HMA combination is expected to constitute the base for triplet combinations and integration of target therapies. Our data contribute to ameliorate the understanding of venetoclax + HMA effectiveness and toxicities in real life.

Genetic characteristics predict response to venetoclax plus hypomethylating agents in relapsed or refractory acute myeloid leukemia.

BACKGROUND: The heterogeneity of relapsed or refractory (R/R) acute myeloid leukemia (AML) leads to no response to venetoclax (VEN)-based therapy in more than half of the patients. Genetic characteristics are considered important predictors for response to treatment in adults with AML. However, the association of genetic characteristics with outcomes receiving VEN-based therapy is incompletely understood in R/R AML. OBJECTIVE: To evaluate the efficacy of VEN combined with hypomethylating agents (HMA) and identify the potential genetic predictors of response in R/R AML. METHODS: A total of 150 R/R AML patients treated with VEN combined with HMA were enrolled in this retrospective study. Outcomes of the response and overall survival (OS) were analyzed. The predictors of response and OS were analyzed by logistic regression or Cox proportional hazards model. RESULTS: With a median of two (range, 1-4) cycles of therapy, the overall response rate was 56.2%, including 22.0% complete remission (CR), 21.3% CR with incomplete hematologic recovery, 2.0% morphologic leukemia-free state, and 10.7% partial remission, in which 25 patients achieved measurable residual disease (MRD)-negative response. With a median follow-up of 11.2 [95% confidence interval (CI), 7.2-14.8] months, 1- and 2-year OS were 46.9% (95% CI, 37.8%-58.1%) and 38.9% (95% CI, 28.7%-52.9%), respectively. Adverse cytogenetics and European Leukemia Net (ELN) risk predicted inferior response to VEN-based therapy. Mutations in IDH1/2, NPM1, ASXL1, and chromatin-cohesin genes predicted superior response to VEN-based therapy, whereas mutations in active signaling genes such as FLT3-ITD and K/NRAS predicted inferior response. CONCLUSION: VEN combined with HMA was effective with R/R AML patients, and the response to treatment was associated with genetic characteristics.

Gilteritinib monotherapy for relapsed/refractory FLT3 mutated acute myeloid leukemia: a real-world, multi-center, matched analysis.

Patients with FLT3-mutated relapsed or refractory (R/R) acute myeloid leukemia (AML) have a dismal prognosis. Gilteritinib is a FLT3 tyrosine kinase inhibitor (TKI) recently approved for patients with R/R AML. We aimed to characterize real-world data regarding gilteritinib treatment in FLT3-mutated R/R AML and to compare outcomes with matched FLT3-mutated R/R AML patients treated with chemotherapy-based salvage regimens. Twenty-five patients from six academic centers were treated with gilteritinib for FLT3-mutated R/R AML. Eighty percent were treated with a prior intensive induction regimen and 40% of them received prior TKI therapy. Twelve patients (48%) achieved complete response (CR) with gilteritinib. The estimated median overall survival (OS) of the entire cohort was eight (CI 95% 0-16.2) months and was significantly higher in patients who achieved CR compared to those who did not (16.3 months, CI 95% 0-36.2 vs. 2.6 months, CI 95% 1.47-3.7; p value = 0.046). In a multivariate cox regression analysis, achievement of CR was the only predictor for longer OS (HR 0.33 95% CI 0.11-0.97, p = 0.044). Prior TKI exposure did not affect OS but was associated with better event-free survival (HR 0.15 95% CI 0.03-0.71, p = 0.016). An age and ELN-risk matched comparison between patients treated with gilteritinib and intensive salvage revealed similar response rates (50% in both groups); median OS was 9.6 months (CI 95% 2.3-16.8) vs. 7 months (CI 95% 5.1-8.9) in gilteritinib and matched controls, respectively (p = 0.869). In conclusion, in the real-world setting, gilteritinib is effective, including in heavily pre-treated, TKI exposed patients.

Sequential treatment with FLAG-IDA/treosulfan conditioning regimen for patients with active acute myeloid leukemia.

Sequential protocols combining salvage chemotherapy with reduced intensity conditioning (RIC) and allogeneic hematopoietic cell transplantation (alloHCT) for high-risk acute myeloid leukemia (AML) have been studied more than a decade. Purpose of this retrospective analysis was to evaluate the anti-leukemic efficacy and toxicity of FLAG-IDA protocol (fludarabine, cytarabine, and idarubicin) followed by treosulfan-based conditioning for patients with active AML. From January 2014 to November 2019, a total of 29 active AML patients [median age, 64 years (range, 23-73)] were treated. All patients completed protocol regimen and were transplanted. Five patients (17%) had grade 3-4 toxicities; therefore, treosulfan was substituted with total body irradiation (TBI) non-myeloablative conditioning. Six (20%) patients died within 30 post-transplant days, all from infectious complications. Out of 23 evaluable patients on day 30, 22 (96%) achieved complete hematologic remission with full donor chimerism. Non-relapse mortality (NRM) rates at 1 and 3 years were 22% and 49%, respectively. Median overall survival (OS) was 12 (95% CI, 4-20) months. OS and disease-free survival were 50% and 46% at 1 year and 28% and 17% at 2 years, respectively. Age, gender, disease burden, number of previous lines, and comorbidity score did not predict survival. Sequential strategy combining FLAG-IDA and treosulfan may offer a salvage option for few selected patients with active AML; however, high NRM presents a major obstacle to treatment success. Future efforts should focus on reducing NRM by moderating regimen intensity and by better selection of patients.

Association of fludarabin, cytarabine, and fractioned gemtuzumab followed by hematopoietic stem cell transplantation for first-line refractory acute myeloid leukemia in children: A single-center experience.

CONTEXT: Acute myeloid leukemia (AML) is a rare disease in children, with only 50% to 60% event-free survival. Among patients with AML, 10% do not respond to first-line chemotherapy. There is no recommendation concerning second-line treatments. Gemtuzumab ozogamicin (GO) is a monoclonal antibody targeting CD33, linked to calicheamicin. We report the efficacy and tolerance of a salvage regimen of fludarabin, cytarabine, and GO (FLA-GO) in patients refractory to first-line treatment. METHODS: Eight patients (median age 14.5 years), who had more than 2% minimal residual disease (MRD) by flow cytometry (MRD flow), received gemtuzumab 3 mg/m² on days 1, 4, 7, associated with cytarabine 2000 mg/m² and fludarabin 30 mg/m² on days 1 to 5. RESULTS: Six patients achieved complete remission (CR) (blast count morphology ≤5 × 10-2 , CR-MRD flow <1 × 10-3 for four patients). Five patients received a second course. We observed 11 episodes of febrile neutropenia, including 6 septicemias without complication. There was no fungal infection or toxic death. Two patients received granulocyte colony stimulating factor. One patient had partial platelet recovery; one, prolonged pancytopenia. All patients received hematopoietic stem cell transplantation (HSCT). We observed five mild-to-severe sinusoidal obstruction syndromes during HSCT procedures, particularly in patients who did not receive defibrotide prophylaxis. At the date of last contact (median follow-up: 58 months; range: 22-78), six patients were in continuous CR with negative MRD. Two patients died of post-HSCT relapse. CONCLUSION: FLA-GO is a good salvage regimen for pediatric refractory AML, with significant but acceptable toxicity. HSCT is mandatory to achieve sustained CR in these patients.

Phase 1/2 study of DFP-10917 administered by continuous intravenous infusion in patients with recurrent or refractory acute myeloid leukemia.

BACKGROUND: DFP-10917, a deoxycytidine nucleoside analogue, has a unique mechanism of action resulting in leukemic cell death when administered for prolonged periods at low doses. The current phase 1/2 study investigated the safety, maximum tolerated dose, and evidence of antileukemic activity for DFP-10917 administered by 7-day or 14-day continuous intravenous infusion in patients with recurrent or refractory acute myeloid leukemia (AML). METHODS: In the phase 1 dose escalation portion of the study, patients were administered DFP-10917 by 7-day continuous intravenous infusion plus 21-day rest (stage 1) or 14-day continuous intravenous infusion plus 14-day rest (stage 2). The primary objectives of phase 1 were to determine the maximum tolerated dose, the phase 2 dose, and the dose-limiting toxicities (DLTs) of DFP-10917. The primary objectives of phase 2 were to evaluate the overall response rate of DFP-10917 using complete response (CR), CR without platelet recovery (CRp), CR with incomplete blood count recovery (CRi) or partial response. RESULTS: In stage 1 of phase 1 (4-35 mg/m2 /day as a 7-day continuous intravenous infusion), a DLT of grade 3 diarrhea occurred at a dose of 35 mg/m2 /day. In stage 2 of phase 1, a dose of 10 mg/m2 /day as a 14-day continuous intravenous infusion resulted in DLTs of prolonged hypocellularity, abdominal pain, diarrhea, and vomiting. The dose of 6 mg/m2 /day as a 14-day continuous intravenous infusion was found to be well tolerated and was selected for phase 2. Response rates in patients in phase 2 (N = 29) were 20.7% CR, 3.4% CRp, and 24.1% CRi. The overall response rate was 48.3% (95% confidence interval, 29.4%-67.5%). CONCLUSIONS: DFP-10917 as a 14-day continuous intravenous infusion at a dose of 6 mg/m2 /day can be administered safely and appears to be effective in patients with recurrent or refractory AML. A phase 3 investigation comparing DFP-10917 monotherapy versus standard of care in an early recurrent or refractory AML setting is warranted.

Impact of genotype in relapsed and refractory acute myeloid leukaemia patients treated with clofarabine and cytarabine: a retrospective study.

The treatment of relapsed/refractory (R/R) acute myeloid leukaemia (AML) remains a challenge. Among salvage chemotherapy regimens, the clofarabine and cytarabine (CLARA) combination has been widely evaluated and has a favourable safety/efficacy balance. Predictive factors of efficacy in patients with R/R AML are unclear, particularly the impact of AML-related gene mutations. We report our single-centre experience on 34 R/R AML patients treated with CLARA, with a focus on the genetic characterization of our cohort. CLARA yielded a 47% response rate among this poor-prognosis AML population, while two patients (5·8%) died due to treatment-related toxicity. The two-year progression-free survival and overall survival rates were 29·4% and 35·3%, respectively. Nine patients (26%) had long-term response with a median follow-up of 39·5 months among the responders, of whom six underwent haematopoietic stem cell transplantation. Adverse karyotype did not correlate with response or survival, and secondary AML were more frequent among responders to CLARA, suggesting that this combination may successfully salvage R/R AML patients regardless of adverse prognostic markers. We also observed that a low mutational burden and absence of splice mutations correlated with prolonged survival after CLARA, suggesting that extensive genotyping may have prognostic implications in R/R AML.

Modified cladribine, cytarabine, and G-CSF as a salvage regimen in patients with relapsed/refractory acute myeloid leukemia: a bridge to myeloablative allogeneic hematopoietic stem cell transplantation.

Patients with primary refractory or early relapsed acute myeloid leukemia (AML) have a dismal prognosis, and the treatment options for these patients are limited. The present study retrospectively examined the efficacy and toxicities of the combination of cladribine 5 mg/m2 per day and intermediate-dose cytarabine 1 g/m2 per day for 5 days and granulocyte colony-stimulating factor (G-CSF) as a salvage treatment in 36 patients with relapsed/refractory AML. Among these, 32 patients had de novo AML, and the remaining 4 patients had secondary AML. The median age for the study cohort was 45.8 years. According to the European LeukemiaNet prognostic index, 5 patients had favorable risk, 18 had intermediate risk, and 11 had poor risk. The complete remission was achieved in 58% of the patients with tolerable toxicities. Fifteen patients underwent stem cell transplantation later. Patients who underwent allogeneic hematopoietic stem cell transplantation had a significantly improved 1-year overall survival compared with those who did not (73% vs. 29%, P < 0.001). The results suggested that, as a salvage regimen, modified cladribine, cytarabine, and G-CSF were effective and well tolerated for patients with relapsed/refractory AML, especially for patients who underwent subsequent stem cell transplantation.

A Pilot Phase II Study of Erlotinib for the Treatment of Patients with Relapsed/Refractory Acute Myeloid Leukemia.

Erlotinib, an epidermal growth factor receptor (EGFR) inhibitor, may have off-target activity inducing acute myeloid leukemia (AML) differentiation, possibly through SYK inhibition. We investigated erlotinib in a pilot phase II study for efficacy in relapsed/refractory AML patients at a dose of 150 mg once daily in 28-day cycles. Twenty-nine patients were treated for a median of 29 days (range 12-142 days). Seven patients (24%) received > 1 cycle of therapy and 12 (41%) discontinued treatment before day 28 due to disease progression. One patient (3%) achieved complete remission and 2 (7%) a > 50% reduction in blasts. The most common toxicities associated with erlotinib were fatigue in 10 patients (34%), diarrhea in 10 (34%), nausea in 8 (28%), and rash in 7 (24%). Only 2 patients (7%) had study drug-related adverse events requiring dose reductions and eventual discontinuation. The main reason for treatment discontinuation was disease progression in 26 patients (90%). All patients had died by the time of the last follow-up. Progression of disease was the primary cause of death in all patients. Median overall survival was 14 weeks (range 2.3-96.9 weeks) and median event-free survival was 5 weeks (range 1.7-21.0 weeks). Erlotinib as a single agent has limited clinical efficacy in patients with relapsed/refractory AML.

High-dose cytarabine as salvage therapy for relapsed or refractory acute myeloid leukemia--is more better or more of the same?

Cytarabine is the backbone of most chemotherapeutic regimens for acute myeloid leukemia (AML), yet the optimal dose for salvage therapy of refractory or relapsed AML (RR-AML) has not been established. Very high dose single-agent cytarabine at 36 g/m(2) (ARA-36) was previously shown to be effective and tolerable in RR-AML. In this retrospective analysis, we aim to describe the toxicity and efficacy of ARA-36 as salvage therapy for patients with AML who are primary refractory to intensive daunorubicin-containing induction or those relapsing after allogeneic stem cell transplant (alloSCT). Fifteen patients, median age 53 years, were included in the analysis. Six patients were treated for induction failure, one had resistant APL, and eight relapsed after alloSCT. Complete remission was achieved in 60% of patients. Surviving patients were followed for a median of 8.5 months. One-year overall survival was 54% (95% CI 30%-86%), and relapse rate from remission (n = 9) was 56%. Grade III/IV pulmonary, infectious, ocular and gastrointestinal toxicities occurred in 26%, 20%, 20% and 20% of patients respectively. Salvage therapy with ARA-36 regimen for RR-AML has considerable efficacy with manageable toxicity in patients with induction failure or post-transplant relapse. Overall survival in these high-risk patients still remains poor.

Early versus late preemptive allogeneic hematopoietic cell transplantation for relapsed or refractory acute myeloid leukemia.

Many patients with relapsed or refractory acute myeloid leukemia (AML) do not receive allogeneic hematopoietic cell transplantation (alloHCT) because they are unable to achieve a complete remission (CR) after reinduction chemotherapy. Starting in January 2003, we prospectively assigned patients with AML with high-risk clinical features to preemptive alloHCT (p-alloHCT) as soon as possible after reinduction chemotherapy. High-risk clinical features were associated with poor response to chemotherapy: primary induction failure, second or greater relapse, and first CR interval <6 months. We hypothesized that any residual disease would be maximally reduced at the time of transplant, resulting in the best milieu and most lead time for developing a graft-versus-leukemia effect and in improved long-term overall survival (OS) without excess toxicity. This analysis studied the effect of transplant timing on p-alloHCT in 30 patients with high-risk clinical features of 156 consecutive AML patients referred for alloHCT. We compared early p-alloHCT within 4 weeks of reinduction chemotherapy before count recovery with late p-alloHCT 4 weeks after reinduction chemotherapy with count recovery. OS and progression-free survival (PFS) at 2 years were not significantly different for early versus late p-alloHCT (OS 23% versus 33%, respectively, P > .1; PFS 18% versus 22%, respectively, P > .1). Day 100 and 1-year transplant-related mortality were similar (33.3% versus 22.2%, P > .1; 44.4% versus 42.9%, P > .1, respectively). Preemptive alloHCT allowed 30 patients to be transplanted who would normally not receive alloHCT. Clinical outcomes for early p-alloHCT are similar to those for late p-alloHCT without excess toxicity. Early p-alloHCT is a feasible alternative to late p-alloHCT for maximizing therapy of AML that is poorly responsive to induction chemotherapy.

Venetoclax plus cytarabine and azacitidine in relapsed/refractory AML: An open-label, single-arm, phase 2 study.

BACKGROUND: The outcome of relapsed/refractory (R/R) acute myeloid leukemia (AML) remains extremely poor. Venetoclax (VEN)-based regimens have shown promise in treating R/R AML. OBJECTIVE: This phase 2 study aimed to systematically evaluate the efficacy and safety of the VAA regimen (VEN plus Cytarabine and Azacitidine) in R/R AML patients. METHODS: Thirty R/R AML patients were enrolled. The study adopted a stepwise ramp-up of VEN dosing, starting with 100 mg on day 1, escalating to 200 mg on day 2, and reaching 400 mg from day 3 to day 9. Cytarabine (10 mg/m2, q12h) was administered intravenously twice daily from days 1 to 10, and Azacitidine (75 mg/m2) was administered via subcutaneous injection once daily from days 1-7. The primary efficacy endpoint was the composite complete remission rate (CRc), including complete response (CR) and complete response with incomplete blood count recovery (CRi). Secondary endpoints included overall survival (OS), duration of response (DOR), and safety analysis. RESULTS: The CRc rate was 63.3% (19/30), with CR in 36.7% of patients and CRi in 26.7%. Notably, 14 (73.7%) of 19 patients achieving CRc showed undetectable measurable residual disease by flow cytometry. With a median follow-up of 10.7 months, the median OS had not been reached, and the median DOR was 18.3 months. The most common grade 3-4 adverse events (AEs) were neutropenia (100%), anemia (96.7%), thrombocytopenia (90.0%), and leukopenia (90.0%). Infections, with pneumonia being the most prevalent (43.3%), were observed, including one fatal case of Pseudomonas aeruginosa septicemia. There were no treatment-related deaths. CONCLUSION: The VAA regimen is an effective and safe option for patients with R/R AML, demonstrating a high CRc rate and manageable safety profile.

Targeting HMGCS1 restores chemotherapy sensitivity in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a common hematological malignancy with overall poor prognosis. Exploring novel targets is urgent and necessary to improve the clinical outcome of relapsed and refractory (RR) AML patients. Through clinical specimens, animal models and cell-level studies, we explored the specific mechanism of 3-hydroxy-3-methylglutaryl coenzyme A synthase 1 (HMGCS1) in AML and the mechanism of targeting HMGCS1 to attenuate cell proliferation, increase chemotherapy sensitivity and improve the occurrence and development of AML. Here, we reveal that HMGCS1 is overexpressed in RR patients and negatively related to overall survival (OS). Knocking out HMGCS1 in AML cells attenuated cell proliferation and increased chemotherapy sensitivity, while stable overexpression of HMGCS1 had the opposite effects. Mechanistically, we identified that knockout of HMGCS1 suppressed mitogen-activated protein kinase (MAPK) pathway activity, while overexpression of HMGCS1 could remarkably enhance the pathway. U0126, a MEK1 inhibitor, offset the effects of HMGCS1 overexpression, indicating that HMGCS1 promotes RR AML through the MAPK pathway. Further, we verified that hymeglusin, a specific inhibitor of HMGCS1, decreases cell growth both in AML cell lines and primary bone marrow cells of AML patients. Furthermore, combination of hymeglusin and the common chemotherapeutic drug cytarabine and adriamycin (ADR) had synergistic toxic effects on AML cells. Our study demonstrates the important role of HMGCS1 in AML, and targeting this protein is promising for the treatment of RR AML.

FLAG/FLAG-Ida Regimen in Secondary and Relapsed/Refractory Acute Myeloid Leukemia-Even in the Era of New Treatment Modalities Still a Significant Player.

(1) Background: Relapsed/refractory (r/r) and secondary acute myeloid leukemia are highlighted by chemoresistance and poor outcomes. The aim of the study was to assess the efficacy and toxicity of fludarabine, cytarabine, and granulocyte-colony stimulation factor (FLAG) with or without idarubicin (-Ida) and to discuss novel therapies in this setting. (2) Methods: Clinical and cytogenetic data on 130 consecutive patients with r/r and secondary AML treated at our center were retrospectively analyzed. (3) Results: There were 48, 56, and 26 patients with relapsed, refractory, and secondary AML, respectively. The median age was 60 years. The overall response was achieved in 70% of patients. The median overall survival (OS) time for the whole group was 9.4 months. In total, 47% of patients proceeded to allogeneic hematopoietic stem cell transplantation (aHSCT) and these patients had significantly prolonged OS compared to the others (63 months vs. 4.2 months; p < 0.001). Among the variables, including age, FLT3 mutation status, European LeukemiaNet (ELN) 2022 classification risk, FLAG vs. FLAG-Ida, and aHSCT, a multivariate analysis revealed that only aHSCT significantly influenced overall survival. (4) Conclusions: FLAG(-Ida) chemotherapy remains an effective salvage chemotherapy for patients with r/r and secondary AML with a plan of proceeding to aHSCT.

Treatment of relapsed or refractory FLT-3 acute myelogenous leukemia with a triplet regimen of hypomethylating agent, venetoclax, and gilteritinib.

Relapsed or refractory (R/R) acute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 (FLT3) mutations remains a difficult and hard to treat entity. Gilteritinib is a potent oral FLT-3 inhibitor that improves overall survival in R/R AML, but studies are limited in combining gilteritinib with a hypomethylating agent and venetoclax treatment backbone (HMA-VEN-GILT). Here we report our experience with HMA-VEN-GILT for 22 R/R FLT3 AML patients. HMA-VEN-GILT yielded an ORR of 77.3% (17/22), CR 4.5% (1/22), CRi 13.6% (3/22), MLFS 59.1% (13/22). Median follow-up was 10.4 months with a relapse rate of 29.4% (5/17), median time to relapse of 69 days (range 35-298 days), 6-month overall survival of 84%, and median OS of 10.1 months. Additionally, 36.4% (8/22) of patients proceeded to hematopoietic stem cell transplant. In conclusion, HMA-VEN-GILT for the treatment of R/R FLT3 AML is feasible and can be used as a bridge to allogeneic transplantation.

Outcomes with chimeric antigen receptor t-cell therapy in relapsed or refractory acute myeloid leukemia: a systematic review and meta-analysis.

Background: We conducted a systematic review and meta-analysis to evaluate outcomes following chimeric antigen receptor T cell (CAR-T) therapy in relapsed/refractory acute myeloid leukemia (RR-AML). Methods: We performed a literature search on PubMed, Cochrane Library, and Clinicaltrials.gov. After screening 677 manuscripts, 13 studies were included. Data was extracted following PRISMA guidelines. Pooled analysis was done using the meta-package by Schwarzer et al. Proportions with 95% confidence intervals (CI) were computed. Results: We analyzed 57 patients from 10 clinical trials and 3 case reports. The pooled complete and overall response rates were 49.5% (95% CI 0.18-0.81, I2 =65%) and 65.2% (95% CI 0.36-0.91, I2 =57%). The pooled incidence of cytokine release syndrome, immune-effector cell associated neurotoxicity syndrome, and graft-versus-host disease was estimated as 54.4% (95% CI 0.17-0.90, I2 =77%), 3.9% (95% CI 0.00-0.19, I2 =22%), and 1.6% (95%CI 0.00-0.21, I2 =33%), respectively. Conclusion: CAR-T therapy has demonstrated modest efficacy in RR-AML. Major challenges include heterogeneous disease biology, lack of a unique targetable antigen, and immune exhaustion.

Healthcare resource utilization and costs during first salvage therapy for relapsed or refractory acute myeloid leukemia in the United States.

Real-world US healthcare resource utilization (HRU) and costs during first salvage therapy for relapsed/refractory (R/R) acute myeloid leukemia (AML) are described using IBM MarketScan® data (1/1/2007-6/30/2020). Treatments included high- (HIC) and low-intensity chemotherapy (LIC) alone, and gilteritinib, other FLT3 tyrosine kinase inhibitors (TKIs), and venetoclax with or without chemotherapy. Patients were diagnosed with R/R AML at ≥18 years of age between 1/1/2017-12/31/2019. Patient monthly all-cause HRU and costs were analyzed using a fixed-effects model. Data from 399 patients were analyzed (HIC, n = 104; LIC, n = 133; gilteritinib, n = 14; other FLT3 TKIs, n = 68; venetoclax, n = 80). Inpatient HRU was generally highest with HIC, whereas outpatient HRU was generally highest with LIC and venetoclax. Total all-cause incremental monthly costs appeared to be highest with HIC ($171,982) and similar for LIC ($60,512), gilteritinib ($47,218), other FLT3 TKIs ($43,218), and venetoclax ($77,566). Results highlight HRU and cost differences for R/R AML during first salvage therapy.

A review of treatment options employed in relapsed/refractory AML.

INTRODUCTION: Acute myeloid leukemia [AML] is a heterogenous group of primary hematopoietic neoplasms arising from myeloid precursor cells. Up to 50% of patients failed to achieve remission with initial therapy and go on to develop refractory AML. Whenever possible, enrollment in a clinical trial in view of the paucity of evidence surrounding a clearly superior treatment modality is recommended, and the therapy which provides the best chance for cure post remission is allogeneic hematopoietic stem cell transplantation [HCT], with much of everyday clinical decision-making in relapsed/refractory (R/R) AML surrounding the choice of the least toxic regimen that could achieve remission and enable prompt HCT. DISCUSSION: We discuss a variety of treatment modalities employed in the R/R AML setting beginning with traditional cytotoxic regimens. We then turn our attention to targeted therapies that have shown efficacy in specific patient populations such as the IDH inhibitors and FLT3 inhibitors and lastly, we turn our attention to immunotherapeutic agents employed in the R/R in the setting, such as CD33 inhibitors and bispecific antibodies. CONCLUSION: It appears increasingly clear that approaching AML as a homogenous disease entity is unsatisfactory in view of the variations in such disease factors as cytogenetic and molecular markers, age, and disease severity at presentation; all of which contribute significantly to heterogeneity of the disease. Moving forward, treating AML would likely require tailored therapy following advances in technology such as molecular profiling, drug sensitivity and resistance testing.

Venetoclax in combination with hypomethylating agents or low dose cytarabine for relapsed and refractory acute myeloid leukemia.

Limited treatment options exist for patients with relapsed/refractory (R/R) acute myeloid leukemia (AML). Venetoclax (VEN) in combination with a hypomethylating agent (HMA) or low-dose cytarabine (LDAC) has been recently approved for treatment-naïve patients unfit for intensive induction. Limited data are available to characterize the efficacy of VEN combinations in R/R AML. We retrospectively analyzed 77 patients with a median of 1 prior therapy (range 0-5) treated with VEN combinations for R/R AML or AML secondary to myelodysplastic syndrome (MDS) progressing after HMA monotherapy. The median overall survival (OS) was 13.1 months (95% CI 9.2-15.1). The median progression-free survival (PFS) was 12 months (95% CI 8.2-15.4) with a median duration of response of 8.9 months (95% CI 5.7-13.9). Overall response rate (ORR) was 68% with a composite complete response (CR) and CR with incomplete hematologic recovery (CRi) rate of 53%. VEN combination therapy is efficacious in R/R AML and further prospective studies are warranted.

Lysosome-mediated chemoresistance in acute myeloid leukemia.

Despite the outstanding advances in understanding the biology underlying the pathophysiology of acute myeloid leukemia (AML) and the promising preclinical data published lastly, AML treatment still relies on a classic chemotherapy regimen largely unchanged for the past five decades. Recently, new drugs have been approved for AML, but the real clinical benefit is still under evaluation. Nevertheless, primary refractory and relapse AML continue to represent the main clinical challenge, as the majority of AML patients will succumb to the disease despite achieving a complete remission during the induction phase. As such, treatments for chemoresistant AML represent an unmet need in this disease. Although great efforts have been made to decipher the biological basis for leukemogenesis, the mechanism by which AML cells become resistant to chemotherapy is largely unknown. The identification of the signaling pathways involved in resistance may lead to new combinatory therapies or new therapeutic approaches suitable for this subset of patients. Several mechanisms of chemoresistance have been identified, including drug transporters, key secondary messengers, and metabolic regulators. However, no therapeutic approach targeting chemoresistance has succeeded in clinical trials, especially due to broad secondary effects in healthy cells. Recent research has highlighted the importance of lysosomes in this phenomenon. Lysosomes' key role in resistance to chemotherapy includes the potential to sequester drugs, central metabolic signaling role, and gene expression regulation. These results provide further evidence to support the development of new therapeutic approaches that target lysosomes in AML.