Phase 1/2 Trial of CLAG-M with Dose-Escalated Mitoxantrone in Combination with Fractionated-Dose Gemtuzumab Ozogamicin for Newly Diagnosed Acute Myeloid Leukemia and Other High-Grade Myeloid Neoplasms.

Gemtuzumab ozogamicin (GO) improves outcomes when added to intensive AML chemotherapy. A meta-analysis suggested the greatest benefit when combining fractionated doses of GO (GO3) with 7 + 3. To test whether GO3 can be safely used with high intensity chemotherapy, we conducted a phase 1/2 study of cladribine, high-dose cytarabine, G-CSF, and dose-escalated mitoxantrone (CLAG-M) in adults with newly diagnosed AML or other high-grade myeloid neoplasm (NCT03531918). Sixty-six patients with a median age of 65 (range: 19-80) years were enrolled. Cohorts of six and twelve patients were treated in phase 1 with one dose of GO or three doses of GO (GO3) at 3 mg/m2 per dose. Since a maximum-tolerated dose was not reached, the recommended phase 2 dose (RP2D) was declared to be GO3. At RP2D, 52/60 (87%) patients achieved a complete remission (CR)/CR with incomplete hematologic recovery (CRi), 45/52 (87%) without flow cytometric measurable residual disease (MRD). Eight-week mortality was 0%. Six- and twelve-month event-free survival (EFS) were 73% and 58%; among favorable-risk patients, these estimates were 100% and 95%. Compared to 186 medically matched adults treated with CLAG-M alone, CLAG-M/GO3 was associated with better survival in patients with favorable-risk disease (EFS: p = 0.007; OS: p = 0.030). These data indicate that CLAG-M/GO3 is safe and leads to superior outcomes than CLAG-M alone in favorable-risk AML/high-grade myeloid neoplasm.

Targeting the membrane-proximal C2-set domain of CD33 for improved CD33-directed immunotherapy.

There is increasing interest in targeting CD33 in malignant and non-malignant disorders. In acute myeloid leukemia, longer survival with the CD33 antibody-drug conjugate gemtuzumab ozogamicin (GO) validates this strategy. Still, GO benefits only some patients, prompting efforts to develop more potent CD33-directed therapeutics. As one limitation, CD33 antibodies typically recognize the membrane-distal V-set domain. Using various artificial CD33 proteins, in which this domain was differentially positioned within the extracellular portion of the molecule, we tested whether targeting membrane-proximal epitopes enhances the effector functions of CD33 antibody-based therapeutics. Consistent with this idea, a CD33V-set/CD3 bispecific antibody (BsAb) and CD33V-set-directed chimeric antigen receptor (CAR)-modified T cells elicited substantially greater cytotoxicity against cells expressing a CD33 variant lacking the entire C2-set domain than cells expressing full-length CD33, whereas cytotoxic effects induced by GO were independent of the position of the V-set domain. We therefore raised murine and human antibodies against the C2-set domain of human CD33 and identified antibodies that bound CD33 regardless of the presence/absence of the V-set domain ("CD33PAN antibodies"). These antibodies internalized when bound to CD33 and, as CD33PAN/CD3 BsAb, had potent cytolytic effects against CD33+ cells. Together, our data provide the rationale for further development of CD33PAN antibody-based therapeutics.

Accuracy of SIE/SIES/GITMO Consensus Criteria for Unfitness to Predict Early Mortality After Intensive Chemotherapy in Adults With AML or Other High-Grade Myeloid Neoplasm.

PURPOSE: With increasing therapeutic alternatives available, there is growing interest in tools that accurately identify patients most suitable for intensive acute myeloid leukemia (AML) chemotherapy. Nowadays, conceptual criteria proposed by an Italian panel of experts are widely used for this purpose. How accurately these Ferrara criteria predict fitness for intensive chemotherapy is unknown. PATIENTS AND METHODS: We assessed the fitness of adults undergoing intensive AML therapy based on Ferrara criteria and determined the accuracy of this assessment for early mortality and survival prediction. RESULTS: Among 655 adults who received curative-intent induction or reinduction chemotherapy with 7 days of standard-dose cytarabine and 3 days of an anthracycline ("7+3") CLAG-M (cladribine, high-dose cytarabine, granulocyte colony-stimulating factor, and mitoxantrone), or reduced-dose CLAG-M, 197 (30%) met at least one of the criteria defining unfitness for intensive chemotherapy (F-unfit). Compared with F-fit patients, the overall survival of F-unfit patients was significantly shorter (median, 4.8 months; 95% CI, 3.6 to 6.5 months v 36.8 months; 95% CI, 27.4 to 73.0 months; P < .001). When used alone, the Ferrara unfitness assessment was more accurate in predicting day 28 and day 100 mortality than the treatment-related mortality score we developed previously (used binary, ≤ 13.1 v > 13.1), as indicated by area under the receiver operating characteristic curve (AUC) values of 0.76 and 0.79 versus 0.66 and 0.62. The predictive accuracy of the Ferrara unfitness assessment could be significantly improved by including additional covariates such as performance status and albumin, yielding AUCs as high as 0.84-0.85 for the prediction of day 28 or day 100 mortality. Prediction of overall survival was less accurate, yielding a c-statistic value as high as 0.75 in multivariable models. CONCLUSION: Ferrara unfitness criteria provide a good prediction tool for shorter-term mortality after intensive AML chemotherapy. Our data may serve as a benchmark for expected outcomes with intensive chemotherapy in F-fit and F-unfit patients.

Number of courses of induction therapy independently predicts outcome after allogeneic transplantation for acute myeloid leukemia in first morphological remission.

Whether the number of chemotherapy cycles required to obtain a first morphological remission affects prognosis of patients with acute myeloid leukemia (AML) remains controversial. To clarify how achievement of early remission might influence outcome of allogeneic hematopoietic cell transplantation (HCT), we studied 220 consecutive adults with AML in first morphological remission who underwent transplantation after myeloablative or nonmyeloablative conditioning to investigate how the number of standard- or high-dose induction courses required to achieve remission impacted post-HCT outcome. Three-year estimates of overall survival were 65% (95% confidence interval [CI] 56% to 73%), 56% (95% CI, 43% to 67%), and 23% (95% CI, 6% to 46%) for patients requiring 1 course, 2 courses, or >2 courses of induction therapy; corresponding relapse estimates were 24% (95% CI, 17% to 31%), 43% (95% CI, 31% to 55%), and 58% (95% CI, 30% to 78%), respectively. After covariate adjustment (minimal residual disease status, conditioning, age, cytogenetic disease risk, type of consolidation chemotherapy, pre-HCT karyotype, and pre-HCT peripheral blood count recovery), the hazard ratios for 2 or >2 induction courses versus 1 induction were 1.16 (95% CI, .73 to 1.85, P = .53) and 2.63 (95% CI, 1.24 to 5.57, P = .011) for overall mortality, and 2.10 (95% CI, 1.27 to 3.48, P = .004) and 3.32 (95% CI, 1.42 to 7.78, P = .006), respectively, for relapse. These findings indicate that the number of induction courses required to achieve morphological remission in AML adds prognostic information for post-HCT outcome that is independent of other prognostic factors.