A Phase I Study of a Combination of 5-Azacyitidine Followed by Lenalidomide In High-Risk MDS or AML Patients with Chromosome 5 Abnormalities – Interim Results of the “AZALE” Trial

Abstract 4000

Lenalidomide has shown single agent activity in patients with MDS (Myelodysplastic Syndromes) and a del(5q) cytogenetic abnormality. Further, studies with the DNA methyltransferase inhibitor 5-azacytidine (5-aza) have been conducted in high-risk MDS (IPSS INT-2 or HIGH) and patients with acute myeloid leukemia (AML) resulting in considerable responses with a low rate of extramedullary toxicity compared to conventional induction chemotherapy (IC). Given the poor outcome of high-risk MDS and AML patients with chromosome 5 abnormalities, there is a significant clinical need to perform studies with new regimens in this patient population.

We report first results of an ongoing phase I clinical trial evaluating the maximum tolerated dose (MTD) of lenalidomide in combination with 5-aza in patients with either high-risk MDS, refractory/relapsed AML or de novo AML not eligible for conventional IC with chromosome 5 abnormalities including monosomy 5 or del(5q). Given the mechanism of action of both drugs and also in contrast to a recent study in non-del(5q) MDS patients, a sequential approach was chosen. In fact, induction therapy consisted of 5-aza (75mg/m² days 1–5) followed by increasing doses of lenalidomide (starting with 10mg p.o., days 6–19). In patients achieving a complete remission this was followed by a combined maintenance therapy every 8 weeks until disease progression.

To determine the MTD, a standard “3+3” design was used. The dose limiting toxicity (DLT) is determined during the first cycle only and is defined as either inability to deliver the full dosing schedule of lenalidomide due to any ≥ Grade 3 non-hematologic toxicity or absence of hematological recovery after completing the 1^st cycle despite complete marrow blast clearance or treatment delay of ≥ 4 weeks as a result of unresolved grade 4 non-hematological toxicity.

Of 8 patients currently enrolled, median age was 67 years (range, 45 to 74 years), interval from primary MDS or AML diagnosis was 9 months (range, 1 to 100 months). IPSS categories were INT-2 (n = 1) and HIGH (n = 3) whereas 4 patients were included with advanced AML. It is of note, that all but two patients had a complex karyotype including a del(5q) abnormality. Prior treatment included IC (n=1), IC plus allogeneic HSCT (n=3) and/or single agent 5-aza (n=3) while 4 patients had received supportive care only prior to study entry.

A median of 2 induction cycles were administered. During the first cycle of cohort I (10mg lenalidomide) and cohort II (15mg lenalidomide) grades 3 to 4 non-hematologic toxicities included febrile neutropenia (n = 3), enterocolitis (n = 1) and pneumonia (n=3) whereas therapy-induced grade 3–4 neutropenia or thrombocytopenia occurred in four and five patients, respectively. The MTD has not been reached yet. One patient (12.5%) with AML showed rapid progression while receiving the 1^st cycle. Out of the remaining seven patients, one (12.5%) achieved a marrow CR together with a partial cytogenetic remission, and six patients (75%) had stable disease. Interestingly, two out of these achieved a partial cytogenetic remission.

These preliminary data of an ongoing phase I trial demonstrate the safety and the potential of a combination of 5-aza and lenalidomide in patients with advanced MDS or AML and a del(5q).