Combined Hypomethylating Agents (HMA) and Histone Deacetylase Inhibitors (HDACi) Exhibit Compelling Activity in Patients with Peripheral T-Cell Lymphoma (PTCL) with High Complete Response Rates in Angioimmunoblastic T-Cell Lymphoma (AITL)
Authors: Falchi Lorenzo , Lue Jennifer Kimberly , Montanari Francesca , Marchi Enrica , Amengual Jennifer E , Sawas Ahmed , Deng Changchun , Khan Karen , Kim Hyea , Atkins Laine E. , Rada Aishling M. , Serge Cremers , O'Connor Owen A. 
Published: October 2019

Abstract
Introduction: PTCL may represent the prototypical epigenetic malignant disorder. First, recurring mutations in important epigenetic regulators, such as TET2, IDH2, and DNMT3, have been described across several PTCL subtypes, though especially in AITL. Second, HDACi have only been approved as single agents in patients with relapsed/refractory (R/R) PTCL, and exhibit T-cell lineage-specific activity across disease subtypes. Thirdly, preclinical evidence from our group suggests marked class synergism between HDACi and HMA. In addition, across a panel of diverse T-cell lymphoma lines, the combination of HDACi and HMA induced the expression of many cancer testis antigens and genes involved in the interferon pathway/viral antigen response. Based on this collective experience, a phase 1/2 trial of romidepsin (ROMI) and oral 5-azacitidine (AZA) was launched to determine if this activity is reproduced in patients with R/R PTCL.
Methods: Patients with R/R lymphoma were eligible for the phase 1, whereas the phase 2 only enrolled patients with PTCL, and included both R/R and treatment-naïve individuals. The dose-escalation portion of the study followed a 3+3 design with progressively increasing dose intensity across 7 cohorts. The phase 1 primary objectives were determination of the maximum tolerated dose and dose-limiting toxicity. Phase 2 primary objectives were overall response rate (ORR, i.e., complete response [CR] + partial response [PR]), progression free survival, and duration of response (DOR).
Results: 36 patients have been enrolled to date, 26 in phase 1 and 10 in phase 2. In the intention-to-treat population the median age was 56 years [23-83] with 59% being males. Twelve patients had Hodgkin lymphoma, 8 had a B-cell lymphoma, and 16 had a T-cell lymphoma (6 enrolled in the phase 1 and 10 in phase 2). The median number of prior therapies was 6 [1-15] for the phase 1 population and 1 [0-6] for the phase 2.
After a median of 2 cycles [0-16], all phase 1 patients have discontinued therapy, whereas 6 out of 10 patients in phase 2 are still on treatment after a median of 2.5 cycles [1-14]. No patient discontinued therapy due to adverse events (AE). The most frequent hematologic G3-4 AE included neutropenia (39%), lymphopenia (39%), and thrombocytopenia (28%). The most frequent non-hematologic G3-4 AE included febrile neutropenia (8%), hyponatremia (5%), and lung infection (5%). Other common G1-2 toxicities included hyperglycemia, hypoalbuminemia, nausea/vomiting, and fatigue. The recommended phase 2 dose for the combination was declared AZA 300 mg days 1-14 and ROMI 14 mg/m2 days 8, 15, and 22 on a 35-day cycle.
Thirty-two patients are evaluable for response. Of these, 27 had measurable disease. The ORR and CR in the overall population are 41% and 22%, respectively. However, while only 2 (11%) patients with non-T-cell lymphoma responded, of which one was a CR, 11 of 14 (79%) patients with T-cell lymphoma responded, including 6 (43%) who attained CR (see waterfall plot in figure). Notably, all 6 evaluable patients with AITL responded, and 3 achieved a CR. Two of these 3 achieved PR before reaching CR. Responses have been durable and the median DOR has not been reached [0.2-13.1+ months]. The AUC for ROMI at 10 mg/m2 (N = 15) and 14 mg/m2 (N = 20) were 2021.5 +/- 1461.3 h*ng/mL and 1565.7 +/- 5656.2 h*ng/mL, respectively, with a median half-life of 4.8 and 4.9 hours respectively, which is comparable to single-agent values.
Conclusions: The combination of AZA and ROMI is well tolerated, with cytopenias being the most common G3-4 AE. The combination appears to exhibit marked T-cell lineage-specific activity. The 100% ORR in AITL patients is unprecedented and warrants detailed follow-up. Ongoing sequencing analysis will evaluate the impact of recurring mutations on the clinical activity of the combination. The study is actively accruing (NCT01998035).
Figure Figure.

Disclosures
O'Connor: ADC Therapeutics: Research Funding; Celgene: Research Funding; Seattle Genetics: Research Funding.