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Blinatumomab superior to chemotherapy for refractory ALL
Median overall survival for patients with ALL was significantly longer with blinatumomab than with chemotherapy.
Inotuzumab
Inotuzumab, which was approved in 2017, differs from blinatumomab in that it is an anti-CD22-calicheamicin conjugate; however, it also showed high response rates in the initial phase 2 trial in relapsed/refractory ALL. The overall response rate was 57%, with 18% achieving a complete response and 63% achieving complete molecular remission.
Of 49 treated patients, 22 patients proceeded to allogeneic transplant, and 5 of those developed VOD.
“Interestingly, four out of five of these patients had received a clofarabine-based preparative regimen, and this likely explains why there was a higher risk of VOD in this study,” she said, noting that the VOD risk has been lower in subsequent studies of inotuzumab.
The international INO-VATE ALL study (NCT01564784) that led to FDA approval was similar in design to the TOWER study in that it compared inotuzumab with standard chemotherapy regimens, and response rates were clearly higher (81% vs. 33%) with inotuzumab (N Engl J Med. 2016 Aug 25;375[8]:740-53).
The VOD risk in the INO-VATE trial was 11%, and it seemed to be higher in those who received dual alkylator–conditioning regimens, which are commonly used in Europe.
Longer-term outcomes after transplant in INO-VATE participants show that median survival has not been reached.
“It’s encouraging that with longer follow-up these patients actually look like they’re doing well,” Dr. Advani said, adding that inotuzumab is a good treatment option for relapsed patients with high disease burden or with CNS disease.
The continuous hookup required for this treatment may be problematic for some younger and older patients, but it is generally not an issue, she noted.
It is important, though, to give as few cycles prior to transplant as possible and to “really think about the preparative regimen to decrease the risk of VOD.”
CAR T-cell therapy
As for CAR T-cell therapy in the relapsed/refractory ALL setting, tisagenlecleucel was approved in 2017 for those up to age 25 years with B-cell precursor ALL that is refractory or in second or later relapse.
Approval was based on a single-arm trial of 63 patients with relapsed or refractory pediatric precursor B-cell ALL, including 35 patients who had prior transplant. The confirmed overall remission rate was 82%, with a 63% CR rate and 19% CRi rate.
“This is a very exciting area,” Dr. Advani said. “There are multiple trials being done in adults with ALL to really look at the older subgroup of patients.”
Overall outcomes
“These treatments we have now really seem to be effective in the relapse setting, but the problem is that once patients relapse and then go to transplant, their overall survival is still poor,” Dr. Advani said. “So the question is how can we improve the up-front treatment of patients so that hopefully they don’t relapse, and hopefully we also can send a smaller number of patients to transplant.”
Two trials seek to address this, she said.
The A041501 study (NCT03150693) is comparing C10403 chemotherapy with C10403 induction followed by two cycles of inotuzumab before continuing with chemotherapy in adults under age 40 years with previously untreated B ALL.
The primary objective is improved 3-year event-free survival, she said, adding that minimal residual disease (MRD) testing will be used and that CD20-positive patients will receive rituximab, as is now standard.
The phase 3 E1910 study (NCT02003222) is evaluating up-front blinatumomab in patients aged 30-70 years with newly diagnosed BCR-ABL–negative B-lineage ALL. This trial was complicated by the recent approval of blinatumomab for MRD-positive disease, which rendered randomization of MRD-positive patients unethical. MRD-negative patients will be randomized, however.
“The hope is that, by incorporating blinatumomab up front, this will again improve outcomes for patients,” she said.
Dr. Advani reported consultancy for Pfizer; research funding from Genzyme, Novartis, Pfizer, and Sigma Tau; and honoraria from Genzyme, Pfizer, and Sigma Tau. She is also on the speakers bureau for Sigma Tau.
