Therapy‐related myeloid neoplasms (t‐MN) are a complication of cytotoxic treatment for primary tumors and autoimmune diseases. We report data on 277 t‐MN patients, recruited between 1999 and 2013 by the Italian Network on Secondary Leukemias (104 retrospectively and 173 prospectively registered). Median age at t‐MN diagnosis was 64 years (range, 21–87). Most frequent primary malignancies (PMs) were lymphoproliferative diseases and breast cancer. One hundred and thirty‐three patients had received chemotherapy (CHT), 43 patients radiotherapy (RT), and 101 patients combined CHT/RT for PM. Median time between cytotoxic treatment and t‐MN was 5.7 years, with t‐MN following RT alone associated with significantly longer latency, compared to CHT or combined CHT/RT (mean, 11.2 vs. 7.1 years, P = 0.0005). The addition of topoisomerase‐II inhibitors to alkylating agents was associated with shorter latency compared to alkylating agents alone (median, 6 vs. 8.4 years, P = 0.02). Median survival was 14.6 months from t‐MN diagnosis, and was significantly longer in patients treated with allogeneic stem cell transplantation. Significant factors for survival at the multivariable analysis included age, adverse karyotype, and degree of anemia. Our data underline the prognostic importance of karyotype and age in t‐MN, similar to de novo acute myeloid leukemia. Treatment approaches should not preclude the use of conventional treatments for younger t‐MN patients, including allogeneic stem cell transplantation as potentially curative approach. Am. J. Hematol. 90:E80–E85, 2015.

Purpose: Epigenetic changes play a role and cooperate with genetic alterations in the pathogenesis of myelodysplastic syndromes (MDS). We conducted a phase II multicenter study on the combination of the DNA-methyltransferase inhibitor 5-azacytidine (5-AZA) and the histone deacetylase inhibitor valproic acid (VPA) in patients with higher risk MDS. Experimental Design: We enrolled 62 patients with MDS (refractory anemia with excess blasts, 39 patients; refractory anemia with excess blasts in transformation, 19 patients; and chronic myelomanocytic leukemia (CMML), 4 patients) and an International Prognostic Scoring System (IPSS) rating of Intermediate-2 (42 patients) or high (20 patients). VPA was given to reach a plasma concentration of >50 μg/mL, then 5-AZA was added s.c. at 75 mg/m² for 7 days in eight monthly cycles. Results: The median overall survival was 14.4 months. At a median follow-up of 12 months (range, 0.7-21.0), the disease progressed in 20 patients, with 21% cumulative incidence of progression. Of 26 patients who completed eight cycles, 30.7% obtained complete or partial remission, 15.4% had a major hematologic improvement, whereas 38.5% showed stable disease. Drug-related toxicity was mild. Favorable prognostic factors for survival were IPSS Intermediate-2 and plasma VPA of ≥50 μg/mL (log rank = 0.013 and 0.007, respectively). Analysis of polymorphisms important for the metabolism of the drugs used in the trial showed that carriers of the CYP2C19*2 variant of cytochrome P450 required higher VPA doses to achieve the target VPA plasma concentration of 50 μg/mL on day 1 of 5-AZA treatment (P = 0.0021). Conclusion: Our data show that the 5-AZA/VPA combination is active and safe in patients with MDS with a poor prognosis. Achievement of VPA therapeutic levels may indeed increase 5-AZA efficacy.

The azanucleotides azacitidine and decitabine have been shown to induce hematologic response and prolong survival in higher-risk myelodysplastic syndromes. They are inhibitors of DNA methyltransferase-1 and induce DNA-hypomethylation. Induction of apoptosis is also clinically relevant, in particular during the first treatment cycles, when cytopenia is a frequent side-effect. Since the hypomethylating effect is reversible, and the malignant clone has been shown to persist in most responding patients, several cycles are necessary to achieve and maintain responses, while treatment interruption is associated with rapid relapse. Methylation studies have shown global and gene-specific hypermethylation in myelodysplastic syndromes, but there seems to be little relation between the degree of demethylation following hypomethylating treatment and hematologic response. The presence of concurrent genomic hypermethylation and hypomethylation may impair the predictive power of current detection techniques. This scenario has been complicated by the identification of epigenetic enzyme mutations, including TET2, IDH1/2, DNMT3A and EZH2, which are important for response to hypomethylating treatment. Changes in azanucleotide metabolism genes may also play a role. In the future, methylation analysis concentrating not only on promoters, but also on gene bodies and intergenic regions, may identify key genes in patients with the highest probability of response to azanucleotides and allow a patient-tailored approach.

BRCA1 plays a pivotal role in the repair of DNA damage, especially following chemotherapy and ionising radiation. We were interested in the regulation of BRCA1 expression in acute myeloid leukaemia (AML), in particular in therapy-related forms (t-AML). Using real-time PCR and Western blot, we found that BRCA1 mRNA was expressed at barely detectable levels by normal peripheral blood granulocytes, monocytes and lymphocytes, whereas control BM-mononuclear cells and selected CD34+ progenitor cells displayed significantly higher BRCA1 expression (P=0.0003). Acute myeloid leukaemia samples showed heterogeneous BRCA1 mRNA levels, which were lower than those of normal bone marrows (P=0.0001). We found a high frequency of hypermethylation of the BRCA1 promoter region in AML (51/133 samples, 38%), in particular in patients with karyotypic aberrations (P=0.026), and in t-AML, as compared to de novo AML (76 vs 31%, P=0.0002). Examining eight primary tumour samples from hypermethylated t-AML patients, BRCA1 was hypermethylated in three of four breast cancer samples, whereas it was unmethylated in the other four tumours. BRCA1 hypermethylation correlated to reduced BRCA1 mRNA (P=0.0004), and to increased DNA methyltransferase DNMT3A (P=0.003) expression. Our data show that reduced BRCA1 expression owing to promoter hypermethylation is frequent in t-AML and that this could contribute to secondary leukaemogenesis.

Therapy-related myeloid neoplasms (t-MNs) include diseases onsetting in patients treated with chemo- and/or radiotherapy for a primary cancer, or an autoimmune disorder. Genomic variants, in particular, in familial cancer genes, may play a predisposing role. Recent advances in deep sequencing techniques have shed light on the pathogenesis of t-MNs, identifying clonal hematopoiesis of indeterminate potential (CHIP) as a frequent first step in the multihit model of t-MNs. CHIP is often detectable prior to any cytotoxic treatment, probably setting the fertile genomic background for secondary leukemogenesis. The evolution pattern toward t-MNs is then a complex process, shaped by the type of cancer therapy, the aging process, and the individual exposures, that favor additional hits, such as the acquisition of TP53 mutations and unfavorable karyotype abnormalities. The pathogenesis of t-MNs differs from MN associated with environmental exposure. Indeed, the genetic aberration patterns of MN developing in atomic bomb survivors show few mutations in classical DNA methylation genes, and a high prevalence of 11q and ATM alterations, together with TP53 mutations. Survival in t-MNs is poor. In addition to the biology of t-MNs, the patient’s previous disease history and the remission status at t-MN diagnosis are significant factors contributing to unfavorable outcome. New drugs active in secondary leukemias include CPX-351, or venetoclax in combination with hypomethylating agents, monoclonal antibodies as magrolimab, or targeted drugs against pathogenic mutations. Allogeneic stem cell transplantation remains the best currently available therapeutic option with curative intent for fit patients with unfavorable genetic profiles.