Double Epigenetic Modulation of High-Dose Chemotherapy (HDC) with Autologous Stem-Cell Transplant (ASCT) for Patients with Refractory or Poor-Risk Relapsed Lymphoma

INTRODUCTION:

More active high-dose regimens are needed for refractory or poor-risk relapsed non-Hodgkin’s (NHL) and Hodgkin’s lymphomas (HL), where standard BEAM offers unsatisfactory results. We previously developed a regimen of infusional gemcitabine with busulfan and melphalan (Gem/Bu/Mel), pursuing the inhibition by gemcitabine of DNA damage repair (Nieto et al, BBMT 2012). Since vorinostat induces chromatin relaxation and facilitates access of chemotherapy to DNA, we combined it with Gem/Bu/Mel, which resulted in a safe and markedly synergistic regimen (Nieto et al, BBMT 2015). Still, the addition of vorinostat to GemBuMel induced upregulation of DNA methyltransferase (DNMT) in lymphoma cells, which could be abrogated preclinically by azacitidine, further increasing tumor-cell kill (Valdez et al, Exp Hematol 2012). These observations led us to study the clinical combination of azacitidine with vorinostat/Gem/Bu/Mel.

METHODS:

Patients ages 12-65 with refractory or poor-risk relapsed lymphomas and adequate end-organ function were eligible. Azacitidine was given on days -8 to -3 at 15-35 mg/m²/day IV (levels 1-3), followed by vorinostat (1,000 mg PO daily, days -8 to -3), gemcitabine (loading dose of 75 mg/m² followed by infusion at 10 mg/m²/min over 4.5 hours, days -8 and -3), busulfan (target daily AUC of 4,000, days -8 to -5) and melphalan (60 mg/m²/day, days -3 and -2). ASCT was on day 0. Patients with CD20⁺ tumors received rituximab (375 mg/m²) on day -9. Dose limiting toxicities (DLT) were defined as any G4-5 nonhematological organ toxicity, or as G3 skin or G3 mucositis lasting >3 days at peak severity. Dose escalation of azacitidine followed a Bayesian design targeting a maximal DLT probability of 25%. We assessed DNMT-3B levels by Western blot in peripheral blood mononuclear cells drawn at baseline and days -5 and -1 in 8 patients treated at the MTD.

RESULTS:

Between 11/13 and 6/15, 60 patients were enrolled: 25 DLBCL (10 double hit), 21 HL, 8 T-NHL (3 PTCL, 2 ALCL, 1 AITL, 1 NK/T, 1 panniculitis-like), 4 follicular NHL and 2 mantle cell (Table 1).

Table 1. Patient population.

Median age (range)	41 (16-65)
Primary induction failure / high-risk/refractory relapse	28% / 62%
Bulky lesions at relapse/PD	58%
Secondary IPI (DLBCL): 0-1 / >1	44% / 56%
LDH at relapse/PD (DLBCL): High / Normal	50% / 50%
Median # prior chemotherapy lines (range)	3 (2-7)
Prior xRT	17%
PET+ at HDC	32%
Status at HDC:	68% CR, 25% PR, 7% unresponsive

Patients were treated at levels 1-3, with the MTD of azacitidine established at level 1 (15 mg/m²/day). The DLT was mucositis, observed at the following frequencies: level 1 (N=37): 16%, level 2 (N=18): 28%, level 3 (N=5): 40%. One patient died from early RSV pneumonia at level 3. The toxicity profile at the MTD was manageable: mucositis (40% G2, 32% G3), self-limited transaminitis (16% G2, 16% G3), self-limited elevation of bilirubin not associated with VOD (19% G2, 22% G3) and dermatitis (13% G2). There were no cardiac, pulmonary, renal or CNS toxicities. Neutrophils and platelets engrafted promptly at median days +9 (7-11) and +12 (8-64), respectively. This toxicity profile is identical to the one seen with Gem/Bu/Mel and vorinostat/Gem/Bu/Mel.

DNMT-3B levels in PBMNC decreased from baseline to day -1 by a median 58% (19-80%) in 7/8 pts. Response assessment and patient outcomes at median follow-up of 11 months (2-21) at are shown on Table 2 and Figures:

Table 2. Activity/outcomes.

	ORR	CR	% EFS	% OS
DLBCL	78%	44%	68%	86%
HL	86%	86%	81%	100%
T-NHL	100%	100%	87.5%	87.5%

CONCLUSIONS:
Azacitidine/vorinostat/Gem/Bu/Mel is feasible, with no increased toxicities compared to Gem/Bu/Mel ± vorinostat, and highly active in refractory or poor-risk relapsed HL and NHL. This regimen warrants further study.