Differentiation syndrome with lower-intensity treatments for acute myeloid leukemia

Sweet syndrome induced by FLT3 inhibitors: case report and literature review

BACKGROUND

Acute febrile neutrophilic dermatosis, also commonly referred to as Sweet syndrome, is often associated with tumors, infections, immune disorders and medications. FLT3 inhibitor-induced Sweet syndrome is a rare complication.

METHODS AND RESULTS

We report a patient with relapsed and refractory acute monocytic leukemia harboring high-frequency FLT3-ITD and DNMT3a mutations. The FLT3 inhibitor gilteritinib was administered for reinduction therapy after failure of chemotherapy with a combination of venetoclax, decitabine, aclarubicin, cytarabine and granulocyte colony-stimulating factor. The leukemia patient achieved remission after 1 month of treatment. However, Sweet syndrome induced by gilteritinib, which was confirmed by skin biopsy, developed during induction therapy. Similar cases of Sweet syndrome following FLT3 inhibitor therapy for acute myeloid leukemia were reviewed.

CONCLUSION

Attention should be given to this rare complication when FLT3 inhibitors are used for acute myeloid leukemia therapy, and appropriate treatments need to be administered in a timely manner.

Emerging DNA Methylome Targets in FLT3-ITD-Positive Acute Myeloid Leukemia: Combination Therapy with Clinically Approved FLT3 Inhibitors

OPINION STATEMENT

The internal tandem duplication (ITD) mutation of the FMS-like receptor tyrosine kinase 3 (FLT3-ITD) is the most common mutation observed in approximately 30% of acute myeloid leukemia (AML) patients. It represents poor prognosis due to continuous activation of downstream growth-promoting signaling pathways such as STAT5 and PI3K/AKT. Hence, FLT3 is considered an attractive druggable target; selective small FLT3 inhibitors (FLT3Is), such as midostaurin and quizartinib, have been clinically approved. However, patients possess generally poor remission rates and acquired resistance when FLT3I used alone. Various factors in patients could cause these adverse effects including altered epigenetic regulation, causing mainly abnormal gene expression patterns. Epigenetic modifications are required for hematopoietic stem cell (HSC) self-renewal and differentiation; however, critical driver mutations have been identified in genes controlling DNA methylation (such as DNMT3A, TET2, IDH1/2). These regulators cause leukemia pathogenesis and affect disease diagnosis and prognosis when they co-occur with FLT3-ITD mutation. Therefore, understanding the role of different epigenetic alterations in FLT3-ITD AML pathogenesis and how they modulate FLT3I's activity is important to rationalize combinational treatment approaches including FLT3Is and modulators of methylation regulators or pathways. Data from ongoing pre-clinical and clinical studies will further precisely define the potential use of epigenetic therapy together with FLT3Is especially after characterized patients' mutational status in terms of FLT3 and DNA methlome regulators.

Differentiation syndrome associated with treatment with IDH2 inhibitor enasidenib: pooled analysis from clinical trials

ABSTRACT

Treatment with enasidenib, a selective mutant isocitrate dehydrogenase isoform 2 (IDH2) inhibitor, has been associated with the development of differentiation syndrome (DS) in patients with acute myeloid leukemia (AML). Studies on the incidence and clinical features of DS are limited in this setting, and diagnosis is challenging because of nonspecific symptoms. This study assessed the incidence, diagnostic criteria, risk factors, and correlation with clinical response of DS based on the pooled analysis of 4 clinical trials in patients with IDH2-mutated AML treated with enasidenib as monotherapy, or in combination with azacitidine or with chemotherapy. Across the total AML population, 67 of 643 (10.4%) had ≥1 any-grade DS event, with highest incidence in patients who received enasidenib plus azacitidine and lowest incidence in patients who received enasidenib plus chemotherapy (13/74 [17.6%] and 2/93 [2.2%]). The most common symptoms of DS were dyspnea/hypoxia (80.6%) and pulmonary infiltrate (73.1%). Median time to onset of first DS event across all studies was 32 days (range, 4-129). Most patients (88.1%) received systemic steroids for treatment of DS. Evaluation of baseline risk factors for DS identified higher levels of bone marrow blasts and lactate dehydrogenase as independent factors associated with increased grade 3 to 5 DS risk. Overall, these results suggest that DS associated with IDH inhibition is manageable, given the benefits of enasidenib treatment in IDH2-mutated AML. We further characterized enasidenib-related DS in these patients and identified risk factors, which could be used for DS management in clinical practice. These trials were registered at www.ClinicalTrials.gov as # NCT01915498, NCT02577406, NCT02677922, and NCT02632708.

A phase 1 study of the irreversible FLT3 inhibitor FF-10101 in relapsed or refractory acute myeloid leukemia

ABSTRACT

FLT3 tyrosine kinase inhibitors (TKIs) have clinical efficacy for patients with FLT3-mutated AML (acute myeloid leukemia), but their impact is limited by resistance in the setting of monotherapy and by tolerability problems when used in combination therapies. FF-10101 is a novel compound that covalently binds to a cysteine residue near the active site of FLT3, irreversibly inhibiting receptor signaling. It is effective against most FLT3 activating mutations, and, unlike other inhibitors, is minimally vulnerable to resistance induced by FLT3 ligand. We conducted a phase 1 dose escalation study of oral FF-10101 in patients with relapsed and/or refractory AML, the majority of whom harbored FLT3-activating mutations and/or had prior exposure to FLT3 inhibitors. Fifty-four participants enrolled in cohorts receiving doses ranging from 10 to 225 mg per day and 50 to 100 mg twice daily (BID). The dose limiting toxicities were diarrhea and QT prolongation. Among 40 response-evaluable participants, the composite complete response rate was 10%, and the overall response rate (including partial responses) was 12.5%, including patients who had progressed on gilteritinib. Overall, 56% of participants had prior exposure to FLT3 inhibitors. The recommended phase 2 dose was 75 mg BID. FF-10101 potentially represents a next-generation advance in the management of FLT3-mutated AML. This trial was registered at www.ClinicalTrials.gov as #NCT03194685.

Small Molecule Menin Inhibitors: Novel Therapeutic Agents Targeting Acute Myeloid Leukemia with KMT2A Rearrangement or NPM1 Mutation

Recent advances have included insights into the clinical value of genomic abnormalities in acute myeloid leukemia (AML) and consequently the development of numerous targeted therapeutic agents that have improved clinical outcome. In this setting, various clinical trials have recently explored novel therapeutic agents either used alone or in combination with intensive chemotherapy or low-intensity treatments. Among them, menin inhibitors could represent a novel group of targeted therapies in AML driven by rearrangement of the lysine methyltransferase 2A (KMT2A) gene, previously known as mixed-lineage leukemia (MLL), or by mutation of the nucleophosmin 1 (NPM1) gene. Recent phase 1/2 clinical trials confirmed the efficacy of SNDX-5613 (revumenib) and KO-539 (ziftomenib) and their acceptable tolerability. Several small molecule menin inhibitors are currently being evaluated as a combination therapy with standard of care treatments. The current paper reviews the recent progress in exploring the inhibitors of menin-KMT2A interactions and their application prospects in the treatment of acute leukemias.

Differentiation Syndrome in Acute Leukemia: APL and Beyond

Differentiation syndrome (DS) is a frequent and potentially life-threatening clinical syndrome first recognized with the advent of targeted therapeutics for acute promyelocytic leukemia (APL). DS was subsequently observed more broadly with targeted therapeutics for acute myeloid leukemia (AML). DS is typically characterized by fever, dyspnea, hypotension, weight gain, pleural or pericardial effusions, and acute renal failure. The incidence in patients with APL ranges from 2 to 37%, with the wide variation likely attributed to different diagnostic criteria, use of prophylactic treatment, and different treatment regimens. Treatment with corticosteroids +/- cytoreductive therapy should commence as soon as DS is suspected to reduce DS-related morbidity and mortality. The targeted anti-leukemic therapy should be discontinued in patients with severe DS. Here, we discuss the pathogenesis of DS, clinical presentations, diagnostic criteria, management strategies, and implementation of prospective tracking on clinical trials.

Structure-Based Drug Design of Novel Triaminotriazine Derivatives as Orally Bioavailable IDH2R140Q Inhibitors with High Selectivity and Reduced hERG Inhibitory Activity for the Treatment of Acute Myeloid Leukemia

Neomorphic IDH2R140Q mutation is commonly found in acute myeloid leukemia (AML), and inhibiting its activity has been validated as an effective treatment for AML. Herein, we report a series of highly potent and selective IDH2R140Q inhibitors. Among them, compound 36 was identified as the most promising inhibitor, with an IC50 value of 29 nM and more than 490-fold selectivity over wild-type IDH2. The compound significantly suppressed D2HG production (IC50 = 10 nM) and induced differentiation in TF-1/IDH2R140Q cells. Furthermore, it showed reasonable pharmacokinetic properties with high bioavailability (F = 90.3%) and an appropriate half-life (T1/2 = 6.4 h). In vivo, oral administration of compound 36 at a dose of 25 mg/kg effectively reduced D2HG levels in the tumor of TF-1/IDH2R140Q xenograft mouse model. Besides, compound 36 displayed little effect on the hERG current. These results suggest that compound 36 has the potential to be an efficacious treatment for AML.

Advances in acute myeloid leukemia differentiation therapy: A critical review

Acute myeloid leukemia (AML) is characterized by impaired differentiation and indefinite proliferation of abnormal myeloid progenitors. Although differentiating agents were deemed to revolutionize AML therapy, most treated non-APL AML patients are refractory or relapse. According to cancer stem cell model, leukemia-initiating cells are the root cause of relapse given their unidirectional potential to generate differentiated AML blasts. Nonetheless, accumulating evidences emphasize the de-differentiation plasticity and leukemogenic potential of mature AML blasts and the frailty of targeting leukemic stem cells per se. This review critically discusses the potential and challenges of (lessons learnt from) conventional and novel differentiating agents in AML therapy. Although differentiating agents might hold promise, they should be exploited within the context of a rationale combination regimen eradicating all maturation/differentiation states of AML cells. The results of the routinely used immunophenotypic markers and/or morphological analyses of differentiation should be carefully interpreted given their propensity to underestimate AML burden.

Efficacy and safety of FDA-approved IDH inhibitors in the treatment of IDH mutated acute myeloid leukemia: a systematic review and meta-analysis

OBJECTIVE

To systematically evaluate the efficacy and safety of FDA-approved isocitrate dehydrogenase (IDH) inhibitors in the treatment of IDH-mutated acute myeloid leukemia (AML).

METHODS

We used R software to conduct a meta-analysis of prospective clinical trials of IDH inhibitors in the treatment of IDH-mutated AML published in PubMed, Embase, Clinical Trials, Cochrane Library and Web of Science from inception to November 15th, 2022.

RESULTS

A total of 1109 IDH-mutated AML patients from 10 articles (11 cohorts) were included in our meta-analysis. The CR rate, ORR rate, 2-year survival (OS) rate and 2-year event-free survival (EFS) rate of newly diagnosed IDH-mutated AML (715 patients) were 47%, 65%, 45% and 29%, respectively. The CR rate, ORR rate, 2-year OS rate, median OS and median EFS of relapsed or refractory (R/R) IDH-mutated AML (394 patients) were 21%, 40%, 15%, 8.21 months and 4.73 months, respectively. Gastrointestinal adverse events were the most frequently occurring all-grade adverse events and hematologic adverse events were the most frequently occurring ≥ grade 3 adverse events.

CONCLUSION

IDH inhibitor is a promising treatment for R/R AML patients with IDH mutations. For patients with newly diagnosed IDH-mutated AML, IDH inhibitors may not be optimal therapeutic agents due to low CR rates. The safety of IDH inhibitors is controllable, but physicians should always pay attention to and manage the differentiation syndrome adverse events caused by IDH inhibitors. The above conclusions need more large samples and high-quality RCTs in the future to verify.

Olutasidenib (FT-2102) induces durable complete remissions in patients with relapsed or refractory IDH1-mutated AML

Olutasidenib (FT-2102) is a potent, selective, oral, small-molecule inhibitor of mutant isocitrate dehydrogenase 1 (mIDH1). Overall, 153 IDH1 inhibitor-naive patients with mIDH1R132 relapsed/refractory (R/R) acute myeloid leukemia (AML) received olutasidenib monotherapy 150 mg twice daily in the pivotal cohort of this study. The median age of participants was 71 years (range, 32-87 years) and the median number of prior regimens received by patients was 2 (1-7). The rate of complete remission (CR) plus CR with partial hematologic recovery (CRh) was 35%, and the overall response rate was 48%. Response rates were similar in patients who had, and who had not, received prior venetoclax. With 55% of patients censored at the time of data cut-off, the median duration of CR/CRh was 25.9 months. The median duration of overall response was 11.7 months, and the median overall survival was 11.6 months. Of 86 patients who were transfusion dependent at baseline, a 56-day transfusion independence was achieved in 29 (34%), which included patients in all response groups. Grade 3 or 4 treatment-emergent adverse events (≥10%) were febrile neutropenia and anemia (n = 31; 20% each), thrombocytopenia (n = 25; 16%), and neutropenia (n = 20; 13%). Differentiation syndrome adverse events of special interest occurred in 22 (14%) patients, with 14 (9%) grade ≥3 and 1 fatal case reported. Overall, olutasidenib induced durable remissions and transfusion independence with a well-characterized and manageable side effect profile. The observed efficacy represents a therapeutic advance in this molecularly defined, poor-prognostic population of patients with mIDH1 R/R AML. This trial was registered at www.clinicaltrials.gov as #NCT02719574.

Gilteritinib: The Story of a Proceeding Success into Hard-to-Treat FLT3-Mutated AML Patients

The traditionally dismal outcome of acute myeloid leukemia (AML) patients carrying the FMS-related tyrosine kinase 3 (FLT3) mutations has been mitigated by the recent introduction of tyrosine kinase inhibitors (TKI) into clinics, such as midostaurin and gilteritinib. The present work summarizes the clinical data that led to the use of gilteritinib in clinical practice. Gilteritinib is a second-generation TKI with deeper single-agent activity than first-generation drugs against both FLT3-ITD and TKD mutations in human studies. Moreover, the phase I/II dose-escalation, dose-expansion Chrysalis trial showed an acceptable safety profile of gilteritinib (diarrhea, elevated aspartate aminotransferase, febrile neutropenia, anemia, thrombocytopenia, sepsis, and pneumonia) and a 49% overall response rate (ORR) in 191 FLT3-mutated relapsed/refractory (R/R) AML patients. In 2019, the pivotal ADMIRAL trial showed that the median overall survival was significantly longer in patients treated with gilteritinib than among those receiving chemotherapy (9.3 vs. 5.6 months, respectively) and the ORR to gilteritinib was 67.6%, outperforming the 25.8% for chemotherapy arm and leading to the license for its clinical use by the US Food and Drug Administration. Since then, several real-world experiences have confirmed the positive results in the R/R AML setting. Finally, gilteritinib-based combinations currently under investigation, with several compounds (venetoclax, azacitidine, conventional chemotherapy, etc.) and some practical tips (maintenance after allogeneic transplantation, interaction with antifungal drugs, extramedullary disease, and onset of resistance), will be analyzed in detail in this review.

IDH1 inhibitor-induced neutrophilic dermatosis in a patient with acute myeloid leukemia

Ivosidenib is an oral inhibitor of mutant Isocitrate dehydrogenase 1 (IDH1). It is approved for treatment of patients with relapsed or refractory IDH1-mutated acute myeloid leukemia (AML) and patients with newly diagnosed IDH1-mutated AML who are 75 years or older or those who are ineligible to receive intensive chemotherapy. While generally well tolerated, differentiation syndrome has been reported in 15-20% of patients. Here, we report a case of acute febrile neutrophilic dermatosis or Sweet's syndrome in conjunction with the use of ivosidenib for the treatment of relapsed AML. We discuss the clinical presentation of this rare entity, review relevant literature, and comment on its association with differentiation syndrome.

SOHO State of the Art Updates and Next Questions: IDH Inhibition

There has been extraordinary progress in the field of targeted therapy for myeloid malignancies in the last few years, especially due to the approval of various agents that can be used as monotherapy or in combination as first-line treatment or when facing a refractory or relapsed disease. Many successful trials have been conducted recently, and a consistent body of work about the efficacy of novel molecules is now available. In this review, we sought to explain how enasidenib and ivosidenib have changed the face of myeloid neoplasm treatment through isocitrate dehydrogenase inhibition and to summarize the trials results that have led to the current commercial indications for the two molecules.