Therapy-related acute promyelocytic leukemia: a systematic review

Therapy-Related Acute Promyelocytic Leukemia Developed During Pembrolizumab Therapy

A 75-year-old male was diagnosed with carcinoma in-situ of the bladder. He failed standard therapy and was started on pembrolizumab to prevent the need for cystectomy. His malignancy recurred, and he was treated with intravesical valrubicin and gemcitabine/docetaxel. Three years after starting pembrolizumab, he developed severe neutropenia and thrombocytopenia. He was treated for suspected auto-immune cytopenias but was later found to have acute promyelocytic leukemia on peripheral blood smear and cytometry. He was hospitalized, treated with all-trans retinoic acid and arsenic trioxide, and is currently in molecular remission. This case describes therapy-related acute promyelocytic leukemia (t-APL) diagnosed while on pembrolizumab. Pembrolizumab is an immune checkpoint inhibitor that exhibits anti-tumor effects. Development of hematologic malignancies after immune checkpoint inhibitor therapy is rare. The definitive etiology of our patient's t-APL is uncertain; however, it is more likely that he developed de novo acute promyelocytic leukemia (APL), which was suppressed by pembrolizumab and later revealed when pembrolizumab was discontinued.

Case report: Identification of acute promyelocytic leukemia during osimertinib resistance followed by granulocyte colony-stimulating factor and pembrolizumab

Background

The occurrence of acute promyelocytic leukemia (APL) during the management of lung cancer is rare and life-threatening. It was mainly reported to be secondary to chemoradiotherapy. A few studies reported an increased incidence of therapy-related acute promyelocytic leukemia (t-APL) after gefitinib became available.

Case presentation

We reported a patient who developed thrombocytopenia after receiving oral osimertinib in combination with intensity-modulated radiotherapy (IMRT). For half a year, she had an unrecoverable low platelet count, which progressed to concomitant leukopenia and the transient appearance of orthochromatic normoblasts in the peripheral blood test, indicating a dormant myeloid disorder. Due to simultaneous resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI), pembrolizumab and granulocyte colony-stimulating factor (G-CSF) were administered, revealing prominent signs of hematological malignancy in a peripheral blood test that was later identified as t-APL.

Conclusion

In general, patients undergoing EGFR-TKI combined with local radiotherapy should be concerned about their hematological assessment. If patients exhibit unrecoverable abnormalities in routine blood tests, a secondary nonsolid malignancy other than myelosuppression should be considered, and further lung cancer treatment should be discontinued.

Therapy‑related acute myeloid leukemia: A case series

Patients with primary cancer receiving chemotherapy and/or radiotherapy may develop therapy-related acute leukemia (t-AL). Therapy-related acute myeloid leukemia (t-AML) accounts for the majority of these cases and is frequently associated with a variety of cytogenetic and molecular abnormalities. The aim of the present study was to explore the clinical characteristics, treatments and prognosis of patients with t-AML. A total of 272 cases of AML treated at our institution between 2016 and 2020 were reviewed, among which nine cases of t-AML were identified for analysis. All patients had received alkylating or topoisomerase II inhibitor chemotherapy drugs for primary cancer treatment and three patients had received radiotherapy. A total of nine patients had been administered recombinant human granulocyte colony-stimulating factor (G-CSF). The median latency period for the nine patients with t-AML was 25 months (range, 10–240 months). The molecular cytogenetic abnormalities included t(15:17)(q22:q21), inv(16)(p13q22), del(5)(q22), CBFB/MYH11(+), FLT3(+), NARS(+), IDH(+), TET2(+), and TP53(+). Out of nine patients with t-AML, eight received chemotherapy, two of whom underwent HSCT. The median survival time of the nine patients with t-AML was 10 months and the 2-year-survival rate was 44.4%. Greater clarity around the diagnosis and treatment is required to improve the outcomes of patients with t-AML.

Hematopoietic Cell Transplantation in the Treatment of Newly Diagnosed Adult Acute Myeloid Leukemia: An Evidence-Based Review from the American Society of Transplantation and Cellular Therapy

The role of hematopoietic cell transplantation (HCT) in the management of newly diagnosed adult acute myeloid leukemia (AML) is reviewed and critically evaluated in this evidence-based review. An AML expert panel, consisting of both transplant and nontransplant experts, was invited to develop clinically relevant frequently asked questions covering disease- and HCT-related topics. A systematic literature review was conducted to generate core recommendations that were graded based on the quality and strength of underlying evidence based on the standardized criteria established by the American Society of Transplantation and Cellular Therapy Steering Committee for evidence-based reviews. Allogeneic HCT offers a survival benefit in patients with intermediate- and high-risk AML and is currently a part of standard clinical care. We recommend the preferential use of myeloablative conditioning in eligible patients. A haploidentical related donor marrow graft is preferred over a cord blood unit in the absence of a fully HLA-matched donor. The evolving role of allogeneic HCT in the context of measurable residual disease monitoring and recent therapeutic advances in AML with regards to maintenance therapy after HCT are also discussed.

New insights into the activities and toxicities of the old anticancer drug doxorubicin

The anthracycline drug doxorubicin is among the most used—and useful—chemotherapeutics. While doxorubicin is highly effective in the treatment of various hematopoietic malignancies and solid tumours, its application is limited by severe adverse effects, including irreversible cardiotoxicity, therapy‐related malignancies and gonadotoxicity. This continues to motivate investigation into the mechanisms of anthracycline activities and toxicities, with the aim to overcome the latter without sacrificing the former. It has long been appreciated that doxorubicin causes DNA double‐strand breaks due to poisoning topoisomerase II. More recently, it became clear that doxorubicin also leads to chromatin damage achieved through eviction of histones from select sites in the genome. Evaluation of these activities in various anthracycline analogues has revealed that chromatin damage makes a major contribution to the efficacy of anthracycline drugs. Furthermore, the DNA‐damaging effect conspires with chromatin damage to cause a number of adverse effects. Structure–activity relationships within the anthracycline family offer opportunities for chemical separation of these activities towards development of effective analogues with limited adverse effects. In this review, we elaborate on our current understanding of the different activities of doxorubicin and their contributions to drug efficacy and side effects. We then offer our perspective on how the activities of this old anticancer drug can be amended in new ways to benefit cancer patients, by providing effective treatment with improved quality of life.

PML-RARA Fusion Transcripts Detectable 8 Months prior to Promyelocytic Blast Crisis in Chronic Myeloid Leukemia

Promyelocytic blast crisis arising from chronic myeloid leukemia (CML) is rare. We present a 40-year-old male who developed promyelocytic blast crisis 17 months after CML diagnosis, confirmed by the presence of the t(15;17) and t(9;22) translocations in the leukemic cells. Preserved nucleic acids from routine BCR-ABL1 testing provided a unique opportunity to evaluate clonal progression over time. Retrospective analysis demonstrated PML-RARA fusion transcripts were first detectable 8 months prior to blast crisis presentation. A review of 21 cases of promyelocytic blasts crisis published in the literature reveals a male predominance with earlier age at onset as compared to females. Interestingly, TKI therapy during chronic phase did not impact the time interval between diagnosis and promyelocytic blast crisis. Treatment with standard acute promyelocytic leukemia regimens provides more favorable outcomes with complete molecular remission. Although rare, it is important to consider a promyelocytic blast crisis when evaluating for transformation of CML due to its effective treatment with specific therapies.

Molecular and cytogenetic characteristics of myeloid malignancies following luminal gastrointestinal cancer

PURPOSE

Luminal gastrointestinal tract cancers (LGC) are common malignancies, and many patients can achieve long-term responses with surgery, cytotoxic and/or targeted therapies, and radiation. The long-term follow-up for patients with durable disease control has not been fully characterized, including subsequent malignancies. Such cases have not been comprehensively described.

PATIENTS AND METHODS

We identified patients evaluated for myeloid malignancies (MyM) who had a prior LGC at our institution over a 35-year period. Patient, disease, and treatment information was collected for analysis. Cytogenetic risk profiles were designated according to the Revised International Prognostic Scoring System for MDS and the European LeukemiaNet Guidelines for AML.

RESULTS

66 patients were included in our cohort with 71 prior LGC diagnoses, including three patients with multiple LGCs. 31 cases were treated with surgery alone, and 37 patients received chemotherapy. The median age at diagnosis of MyM was 71.8 years (range, 36.2-90.5), with median duration between initiation of treatment of LGC and diagnosis MyM of 7.9 years (range 0.005-38.8). Intermediate or adverse (AML)/poor-very poor (MDS) cytogenetic risk was common, occurring in 43% of MDS patients and 100% of AML patients; deletion 5q was the most common cytogenetic abnormality overall. DNMT3A mutations were the most common molecular alteration (6 patients with 7 mutations).

CONCLUSIONS

Among patients with MyM following LGC, a high proportion harbored cytogenetic changes, many of which were adverse or poor-risk. Deletion 5q and mutated DNMT3A were the most common abnormalities identified.

Concentration-response studies of the chromosome-damaging effects of topoisomerase II inhibitors determined in vitro using human TK6 cells

Topoisomerase II (topo II) inhibitors are commonly used as chemotherapy to treat multiple types of cancer, though their use is also associated with the development of therapy related acute leukemias. While the chromosome-damaging effects of etoposide, a topo II poison, have been proposed to act through a threshold mechanism, little is known about the chromosome damaging effects and dose responses for the catalytic inhibitors of the enzyme. The current study was designed to further investigate the potencies and concentration-response relationships of several topoisomerase II inhibitors, including the topoisomerase II poison etoposide, as well as catalytic inhibitors aclarubicin, merbarone, ICRF-154 and ICRF-187 using both a traditional in vitro micronucleus assay as well as a flow-cytometry based version of the assay. Benchmark dose (BMD) analysis was used to identify models that best fit the data and estimate a BMD, in this case the concentration at which a one standard deviation increase above the control frequency would be expected. All of the agents tested were potent in inducing micronuclei in human lymphoblastoid TK6 cells, with significant increases seen at low micromolar, and in the cases of aclarubicin and etoposide, at low nanomolar concentrations. Use of the anti-kinetochore CREST antibody with the microscopy-based assay demonstrated that the vast majority of the micronuclei originated from chromosome breakage. In comparing the two versions of the micronucleus assay, significant increases in micronucleated cells were observed at similar or lower concentrations using the traditional microscopy-based assay. BMD modeling of the data exhibited several advantages and proved to be a valuable alternative for concentration-response analysis, producing points of departure comparable to those derived using traditional no-observed or lowest-observed genotoxic effect level (NOGEL or LOGEL) approaches.

Producing irreversible topoisomerase II-mediated DNA breaks by site-specific Pt(II)-methionine coordination chemistry

Human type II topoisomerase (Top2) isoforms, hTop2α and hTop2β, are targeted by some of the most successful anticancer drugs. These drugs induce Top2-mediated DNA cleavage to trigger cell-death pathways. The potency of these drugs correlates positively with their efficacy in stabilizing the enzyme-mediated DNA breaks. Structural analysis of hTop2α and hTop2β revealed the presence of methionine residues in the drug-binding pocket, we therefore tested whether a tighter Top2-drug association may be accomplished by introducing a methionine-reactive Pt²⁺ into a drug to further stabilize the DNA break. Herein, we synthesized an organoplatinum compound, etoplatin-N2β, by replacing the methionine-juxtaposing group of the drug etoposide with a cis-dichlorodiammineplatinum(II) moiety. Compared to etoposide, etoplatin-N2β more potently inhibits both human Top2s. While the DNA breaks arrested by etoposide can be rejoined, those captured by etoplatin-N2β are practically irreversible. Crystallographic analyses of hTop2β complexed with DNA and etoplatin-N2β demonstrate coordinate bond formation between Pt²⁺ and a flanking methionine. Notably, this stable coordinate tether can be loosened by disrupting the structural integrity of drug-binding pocket, suggesting that Pt²⁺ coordination chemistry may allow for the development of potent inhibitors with protein conformation-dependent reversibility. This approach may be exploited to achieve isoform-specific targeting of human Top2s.

CD34(+) therapy-related acute promyelocytic leukemia in a patient previously treated for breast cancer

Therapy-related acute myeloid leukemia (AML) is a long term complication of chemotherapy for a variety of cancers. In most cases, the marrow demonstrates high risk cytogenetics and the prognosis is poor. In a minority of patients "good risk" cytogenetics, including t(15;17)(q22;q12), are seen and the patient's prognosis is similar to those who have de novo disease. Currently we present a patient who developed therapy-related acute promyelocytic leukemia (APL) after chemoradiotherapy for breast cancer. This case was especially atypical because the leukemic cells were CD34(+), which is an unusual immunophenotype for APL. Recognition that this patient had APL, rather than the more common therapy-related MDS or AML, was imperative to initiate chemotherapy in a timely manner.

Survival of de novo and secondary acute promyelocytic leukemia: a propensity-matched analysis of the SEER database

Prior studies demonstrated that secondary acute promyelocytic leukemia (sAPL) and de novo APL may but not consistently have similar overall survival (OS). We used the Surveillance, Epidemiology, and End Results (SEER) 13 database to compare their OS. Patients with sAPL (n = 90), compared to de novo APL (n = 1600), were more likely to be older, White and diagnosed after year 2005. Mortality rate at 1 month (28.9% vs. 23.0%, p = 0.20) and 5-year OS (42% vs. 50%, p = 0.24) was similar between sAPL and de novo APL. In a multivariate analysis, sAPL was associated with similar OS as de novo APL (hazard ratio, HR 1.11; 95% confidence interval, CI 0.78-1.58; p = 0.546). This population-based study demonstrated no difference in OS or early mortality rate between sAPL and de novo APL. sAPL can be managed very similarly to de novo APL and does not need to be excluded from clinical trials of APL.

Global characteristics of childhood acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) comprises approximately 5-10% of childhood acute myeloid leukemia (AML) cases in the US. While variation in this percentage among other populations was noted previously, global patterns of childhood APL have not been thoroughly characterized. In this comprehensive review of childhood APL, we examined its geographic pattern and the potential contribution of environmental factors to observed variation. In 142 studies (spanning >60 countries) identified, variation was apparent-de novo APL represented from 2% (Switzerland) to >50% (Nicaragua) of childhood AML in different geographic regions. Because a limited number of previous studies addressed specific environmental exposures that potentially underlie childhood APL development, we gathered 28 childhood cases of therapy-related APL, which exemplified associations between prior exposures to chemotherapeutic drugs/radiation and APL diagnosis. Future population-based studies examining childhood APL patterns and the potential association with specific environmental exposures and other risk factors are needed.

Expression of RKIP in chronic myelogenous leukemia K562 cell and inhibits cell proliferation by regulating the ERK/MAPK pathway

RAF kinase inhibitor protein (RKIP) is a negative regulator of the RAS-mitogen-activated protein kinase/extracellular signal-regulated kinase signaling cascade. We investigated the expression of RKIP in chronic myelogenous leukemia (CML) K562 cells and the effects of RKIP on the characteristics of K562 cells. The recombinant plasmid pcDNA3.1-RKIP was established and transfected into K562 cells with the help of Lipofectamine 2000. At the same time, the RKIP-siRNA was transfected into K562 cells in another group. The expressions of RKIP in all groups were assayed by Western blot after 48 h. MTT (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to analyze the cell viability. Flow cytometry (FCM) was used to examine the cell cycle and cell apoptosis. Colony forming unit (CFU) assay was used to analyze the effect of RKIP on the clonogenic growth of CML cells. Western blot or luciferase reporter assay was used to detect the effect of RKIP on the level of phospho-ERK1/2 or the transcriptional activity of NF-κB. Western blot analysis showed that the plasmid pcDNA3.1-RKIP or RKIP-siRNA significantly enhanced or decreased RKIP expression (p < 0.01), respectively. In addition, MTT, FCM, and CFU assay indicated that the overexpression of RKIP significantly lowered the cell viability, cell proliferation and the clonogenic growth (p < 0.05), but improved cell apoptosis (p < 0.01). Western blot analysis or luciferase reporter assay showed that the level of phospho-ERK1/2 or the transcriptional activity of NF-κB was strongly inhibited by overexpression of RKIP. All these results could bring us a new perspective for biological therapy in myelogenous leukemia in the future.

Topoisomerase II and leukemia

Type II topoisomerases are essential enzymes that modulate DNA under- and overwinding, knotting, and tangling. Beyond their critical physiological functions, these enzymes are the targets for some of the most widely prescribed anticancer drugs (topoisomerase II poisons) in clinical use. Topoisomerase II poisons kill cells by increasing levels of covalent enzyme-cleaved DNA complexes that are normal reaction intermediates. Drugs such as etoposide, doxorubicin, and mitoxantrone are frontline therapies for a variety of solid tumors and hematological malignancies. Unfortunately, their use also is associated with the development of specific leukemias. Regimens that include etoposide or doxorubicin are linked to the occurrence of acute myeloid leukemias that feature rearrangements at chromosomal band 11q23. Similar rearrangements are seen in infant leukemias and are associated with gestational diets that are high in naturally occurring topoisomerase II-active compounds. Finally, regimens that include mitoxantrone and epirubicin are linked to acute promyelocytic leukemias that feature t(15;17) rearrangements. The first part of this article will focus on type II topoisomerases and describe the mechanism of enzyme and drug action. The second part will discuss how topoisomerase II poisons trigger chromosomal breaks that lead to leukemia and potential approaches for dissociating the actions of drugs from their leukemogenic potential.