Frontline Therapy for Older Patients (pts) with Acute Myeloid Leukemia (AML): Clofarabine Plus Low-Dose Cytarabine Induction Followed by Prolonged Consolidation with Clofarabine Plus Low-Dose Cytarabine Alternating with Decitabine

Abstract 336

Standard therapy (e.g. “3+7”) of newly diagnosed older pts (≥ 60 yrs) with AML is characterized by low response rates, short response durations, and substantial toxicities. New approaches are therefore actively explored in clinical trials. Clofarabine is a second generation deoxyadenosine nucleoside analogue with activity in older pts with frontline AML and presence of unfavorable prognostic factors. In our experience, the combination of clofarabine with low-dose cytarabine achieved higher response rates at no increase of toxicity compared with clofarabine alone (Faderl S et al. Blood 2008). Based on the initial experience, we have designed a combination of lower-dose clofarabine plus low-dose cytarabine induction followed by a prolonged consolidation of these drugs alternating with decitabine to improve survival and maintain the high response rates from the earlier study. Pts were eligible if ≥ 60 yrs of age with newly diagnosed AML. Pts were excluded for ECOG PS > 2, creatinine > 1.5 mg/dL, cardiac ejection fraction < 40%, and prior therapy with clofarabine or decitabine. Induction therapy consisted of clofarabine 20mg/m² i.v daily × 5 days plus cytarabine 20mg s.c. twice daily × 10 days. Responding pts could receive up to 17 courses of consolidation therapy of clofarabine plus cytarabine (over 3 and 7 days, respectively) during courses 1–2, 6–8, 12–14 alternating with decitabine 20mg/m² i.v. daily for 5 days during courses 3–5, 9–11, and 15–17. All pts received antibiotic prophylaxis with levofloxacin, valacyclovir and itraconazole (or equivalent). Fifty-nine pts have been accrued with a median age of 70 yrs (range 60–81), of whom 17 pts (29%) were ≥ 75 yrs. Eleven pts (19%) had a PS of 2. Seven pts (12%) had a WBC of > 20,000/mcl at diagnosis. Thirty pts (51%) had abnormal cytogenetics. Molecular profile: FLT3/ITD 5 pts (9%), FLT3/D835 2 (4), NPM1 6 (13), Ras 2 (4). Thirteen pts (22%) had prior MDS (4 pts prior azacitidine; 2 pts prior lenalidomide) and 17 pts (29%) had secondary AML (Hx of prior chemo and/or XRT). Of 57 pts evaluable for response, 35 (61%) achieved CR and 4 (7%) CRp for an ORR of 68%. Six pts (11%) required more than one course to response. The ORR for pts with diploid vs abnormal cytogenetics was 79% vs 57%; for pts with prior MDS 46% vs 82% for pts with neither MDS nor secondary AML. All 7 pts with a FLT3 mutation responded. With a median follow up of 11.6 months (1.1-20.2+), 16 pts relapsed. Responses (CR) are ongoing in 19 pts. Median CR duration is 14.1 mos (1.8-16.4). Six pts (10%) died on study. Only one pt suffered an early death ≤ 28 days from induction (C1D26). Deaths were due to myelosuppression-associated infectious complications. Median overall survival for all 59 pts was 18.1 mos (0.8-20.2+). Median overall survival for responding patients has not been reached. The median number of consolidation cycles received by pts in CR/CRp was 4 (0-14). Fifteen of these pts have so far received at least 6 consolidation cycles. Most toxicities were ≤ grade 2 and included rash (64%), nausea (61%), transaminase elevations (58%), bilirubinemia (51%), diarrhea (32%), mucositis, creatinine evelations, and headache (12% each). Among toxicities > grade 2, transaminase elevations (14%) and bilirubinemia (5%) were most frequent. One pt (65 yr old female) experienced renal failure and pulmonary edema shortly following start of the induction. Myelosuppression and neutropenic fever were common, but prolonged myelosuppression in responders was rare. In summary, clofarabine plus low-dose cytarabine achieves high response rates with a manageable toxicity profile and low induction mortality in pts ≥ age 60 with previously untreated AML. Longer follow up and comparisons with conventional therapy will help establish whether or not this combination also has a survival advantage.