Effects of azacitidine in 93 patients with IDH1/2 mutated acute myeloid leukemia/myelodysplastic syndromes: a French retrospective multicenter study

Isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) mutations in Myeloid Neoplams (MNs) exhibit DNA hypermethylation via 2-hydroxyglutarate (2HG) over-production. Clinical impact of azacitidine (AZA) remains inconsistent in IDH1/2-mutated MNs and the potential of serum 2HG as a suitable marker of response to AZA is unknown. To address these questions, we retrospectively analyzed 93 MNs patients (78 AML, 11 MDS, 4 CMML) with IDH1/2 mutations treated with AZA. After a median of 5 cycles of AZA, overall response rate was 28% (including 15% complete remission) and median OS was 12.3 months (significantly shorter in AML compared to MDS/CMML patients). In multivariate analysis of AML patients, DNMT3A mutation was associated with shorter OS while IDH1/2 mutation subtypes had no independent impact. No difference was observed in serum 2HG levels upon AZA treatment between responding and refractory patients suggesting that serum 2HG cannot be used as a surrogate marker of AZA response.

Ivosidenib to treat adult patients with relapsed or refractory acute myeloid leukemia

Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are key metabolic enzymes that convert isocitrate to alpha-ketoglutarate (alphaKG). Somatic point mutations in IDH1/2 that are found in rare distinct subsets of cancers confer a gain of function in cancer cells which results in the accumulation and secretion in vast excess of the oncometabolite D-2-hydroxyglutarate (D-2HG). Overproduction of D-2HG interferes with cellular metabolism and epigenetic regulation, contributing to oncogenesis. High levels of D-2HG inhibit alphaKG-dependent dioxygenases including histone, DNA and RNA demethylases, resulting in histone, DNA and RNA hypermethylation and cell differentiation blockade. In addition, D-2HG is a biomarker suitable for the detection of IDH1/2 mutations at diagnosis, and is also predictive of clinical response. The U.S. Food and Drug Administration (FDA) approved ivosidenib, a mutant-IDH1 enzyme inhibitor, for patients with relapsed or refractory IDH1-mutated acute myeloid leukemia (AML) in 2018, and also as front-line therapy for newly diagnosed elderly patients 75 years or older or who are ineligible to receive intensive chemotherapy in 2019. Ivosidenib represents a novel drug class for targeted therapy in AML.

Variation in transplacental transfer of tyrosine kinase inhibitors in the human perfused cotyledon model

BACKGROUND

The use of tyrosine kinase inhibitors (TKis) during pregnancy in humans remains rare, and little data are available on their transplacental passage. Erlotinib and gefitinib are the first-line targeted therapy in case of stage IV nonsmall-cell lung cancer with an EGFR-activating mutation. There are no data available regarding the comparative use of these TKis in pregnant patients. We aimed to compare the transplacental transfer of gefitinib, imatinib and erlotinib, using the ex vivo method of human perfused cotyledon, and to determine the placental accumulation of TKis.

MATERIALS AND METHODS

Term placentas were perfused after delivery with gefitinib, imatinib and erlotinib at targeted maternal concentrations around the steady-state plasma trough concentration (i.e. 500, 1000 and 1500 ng/ml, respectively). Samples from fetal and maternal circulations were collected in order to monitor TKis concentrations. Main transfer parameters such as fetal transfer rate (FTR), clearance index (CI) and placental uptake were assessed.

RESULTS

Mean FTR of gefitinib, imatinib and erlotinib were 16.8%, 10.6% and 31.4%, respectively. Mean CI of gefitinib, imatinib and erlotinib were 0.59, 0.48 and 0.93, respectively. Placental uptake in cotyledon was 0.030% %, 0.010% and 0.003% for gefitinib, imatinib and erlotinib, respectively, corresponding to a mean mass of 27.7 µg for gefitinib, 15.7 µg for imatinib and 6.8 µg for erlotinib.

CONCLUSION

The results suggest that TKis cross the placenta at therapeutic level. Particularly, erlotinib crosses the placenta at a higher rate than gefitinib or imatinib. All of them have a very low placental uptake. These data may suggest that gefitinib should be preferred to erlotinib for the treatment of pregnant woman with lung cancer harboring an EGFR-activating mutation, during the second and third trimesters of pregnancy.

Somatic RAS mutations occur in a large proportion of sporadic RET-negative medullary thyroid carcinomas and extend to a previously unidentified exon

CONTEXT

Medullary thyroid carcinoma (MTC) is characterized by proto-oncogene RET mutations in almost all hereditary cases as well as in more than 40% of sporadic cases. Recently, a high prevalence of RAS mutations was reported in sporadic MTC, suggesting an alternative genetic event in sporadic MTC tumorigenesis.

OBJECTIVE

This study aimed to extend this observation by screening somatic mutational status of RET, BRAF, and the three RAS proto-oncogenes in a large series of patients with MTC.

MATERIALS AND METHODS

Direct sequencing of RET (exons 8, 10, 11, 13, 14, 15, 16), BRAF (exons 11 and 15), and KRAS, HRAS, and NRAS genes (exons 2, 3, and 4) was performed on DNA prepared from 50 MTC samples, including 30 sporadic cases.

RESULTS

Activating RET mutations were detected in the 20 hereditary cases (germline mutations) and in 14 sporadic cases (somatic mutations). Among the 16 sporadic MTC without any RET mutation, eight H-RAS mutations and five K-RAS mutations were found. Interestingly, nine RAS mutations correspond to mutation hot spots in exons 2 and 3, but the other four mutations were detected in exon 4. The RET and RAS mutations were mutually exclusive. No RAS gene mutation was found in hereditary MTC, and no BRAF or NRAS mutation was observed in any of the 50 samples.

CONCLUSIONS

Our study confirms that RAS mutations are frequent events in sporadic MTC. Moreover, we showed that RAS mutation analysis should not be limited to the classical mutational hot spots of RAS genes and should include analysis of exon 4.