Hyper-CVAD (fractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone) with sequential blinatumomab is highly effective as frontline therapy for Philadelphia Chromosome (Ph)–negative B-cell acute lymphoblastic leukemia (ALL), according to results of a phase 2 study reported at the annual meeting of the American Society of Hematology.
Favorable minimal residual disease (MRD) negativity and overall survival with low higher-grade toxicities suggest that reductions in chemotherapy in this setting are feasible, said Nicholas J. Short, MD, of the University of Texas MD Anderson Cancer Center, Houston.
While complete response rates with current ALL therapy are 80%-90%, long-term overall survival is only 40%-50%. Blinatumomab, a bispecific T-cell–engaging CD3-CD19 antibody, has been shown to be superior to chemotherapy in relapsed/refractory B-cell ALL, and to produce high rates of MRD eradication, the most important prognostic factor in ALL, Dr. Short said at the meeting, which was held virtually.
The hypothesis of the current study was that early incorporation of blinatumomab with hyper-CVAD in patients with newly diagnosed Ph-negative B-cell ALL would decrease the need for intensive chemotherapy and lead to higher efficacy and cure rates with less myelosuppression. Patients were required to have a performance status of 3 or less, total bilirubin 2 mg/dL or less and creatinine 2 mg/dL or less. Investigators enrolled 38 patients (mean age, 37 years,; range, 17-59) with most (79%) in performance status 0-1. The primary endpoint was relapse-free survival (RFS).
Study details
Patients received hyper-CVAD alternating with high-dose methotrexate and cytarabine for up to four cycles followed by four cycles of blinatumomab at standard doses. Those with CD20-positive disease (1% or greater percentage of the cells) received eight doses of ofatumumab or rituximab, and prophylactic intrathecal chemotherapy was given eight times in the first four cycles. Maintenance consisted of alternating blocks of POMP (6-mercaptopurine, vincristine, methotrexate, prednisone) and blinatumomab. When two patients with high-risk features experienced early relapse, investigators amended the protocol to allow blinatumomab after only two cycles of hyper-CVAD in those with high-risk features (e.g., CRLF2 positive by flow cytometry, complex karyotype, KMT2A rearranged, low hypodiploidy/near triploidy, TP53 mutation, or persistent MRD). Nineteen patients (56%) had at least one high-risk feature, and 82% received ofatumumab or rituximab. Six patients were in complete remission at the start of the study (four of them MRD negative).
Complete responses
After induction, complete responses were achieved in 81% (26/32), with all patients achieving a complete response at some point, according to Dr. Short. The MRD negativity rate was 71% (24/34) after induction and 97% (33/34) at any time. Among the 38 patients, all with complete response at median follow-up of 24 months (range, 2-45), relapses occurred only in those 5 patients with high-risk features. Twelve patients underwent transplant in the first remission. Two relapsed, both with high-risk features. The other 21 patients had ongoing complete responses.
RFS at 1- and 2-years was 80% and 71%, respectively. Five among seven relapses were without hematopoietic stem cell transplantation, and 2 were post HSCT. Two deaths occurred in patients with complete responses (one pulmonary embolism and one with post-HSCT complications). Overall survival at 1 and 2 years was 85% and 80%, respectively, with the 2-year rate comparable with prior reports for hyper-CVAD plus ofatumumab, Dr. Short said.
The most common nonhematologic grade 3-4 adverse events with hyper-CVAD plus blinatumomab were ALT/AST elevation (24%) and hyperglycemia (21%). The overall cytokine release syndrome rate was 13%, with 3% for higher-grade reactions. The rate for blinatumomab-related neurologic events was 45% overall and 13% for higher grades, with 1 discontinuation attributed to grade 2 encephalopathy and dysphasia.
“Overall, this study shows the potential benefit of incorporating frontline blinatumomab into the treatment of younger adults with newly diagnosed Philadelphia chromosome–negative B-cell lymphoma, and shows, as well, that reduction of chemotherapy in this context is feasible,” Dr. Short stated.
“Ultimately, often for any patients with acute leukemias and ALL, our only chance to cure them is in the frontline setting, so our approach is to include all of the most effective agents we have. So that means including blinatumomab in all of our frontline regimens in clinical trials – and now we’ve amended that to add inotuzumab ozogamicin with the goal of deepening responses and increasing cure rates,” he added.
Dr. Short reported consulting with Takeda Oncology and Astrazeneca, and receiving research funding and honoraria from Amgen, Astella, and Takeda Oncology.
SOURCE: Short NG et al. ASH 2020, Abstract 464.