Jeffrey M. Venstrom

KIR and HLA Genotypes Are Associated with Disease Progression and Survival following Autologous Hematopoietic Stem Cell Transplantation for High-Risk Neuroblastoma

Purpose: NK cells exhibit cytotoxicity against neuroblastoma. Gene polymorphisms governing NK cell function, therefore, may influence prognosis. Two highly polymorphic genetic loci instrumental in determining NK cell responses encode the NK cell killer immunoglobulin-like receptors (KIR) and their class I human leukocyte antigen (HLA) ligands. We hypothesized that patients with a “missing ligand” KIR-HLA compound genotype may uniquely benefit from autologous hematopoietic stem cell transplantation (HSCT). Experimental Design: One hundred sixty-nine patients treated with autologous HSCT for stage IV neuroblastoma underwent KIR and HLA genotyping. Patients were segregated according to the presence or absence of HLA ligands for autologous inhibitory KIR. Univariate and multivariate analyses were done for overall and progression-free survival. Results: Sixty-four percent of patients lacked one or more HLA ligands for inhibitory KIR. Patients lacking a HLA ligand had a 46% lower risk of death [hazard ratio, 0.54; 95% confidence interval (95% CI), 0.35-0.85; P = 0.007] and a 34% lower risk of progression (hazard ratio, 0.66; 95% CI, 0.44-1.0; P = 0.047) at 3 years compared with patients who possessed all ligands for his/her inhibitory KIR. Among all KIR-HLA combinations, 16 patients lacking the HLA-C1 ligand for KIR2DL2/KIR2DL3 experienced the highest 3-year survival rate of 81% (95% CI, 64-100). Survival was more strongly associated with “missing ligand” than with tumor MYCN gene amplification. Conclusion: KIR-HLA immunogenetics represents a novel prognostic marker for patients undergoing autologous HSCT for high-risk neuroblastoma. (Clin Cancer Res 2009;15(23):7330–4)

CALGB 150905 (Alliance): Rituximab Broadens the Antilymphoma Response by Activating Unlicensed NK Cells

Du and colleagues report that a “missing ligand” genotype predictive of unlicensed NK cells was associated with higher progression-free survival in 101 follicular lymphoma patients treated with rituximab-containing mAb combinations, and that rituximab triggered responses in vitro from healthy-donor unlicensed NK cells. Natural killer (NK) cells contribute to clinical responses in patients treated with rituximab, but the rules determining NK-cell responsiveness to mAb therapies are poorly defined. A deeper understanding of the mechanisms responsible for antibody-dependent cellular cytotoxicity (ADCC) could yield useful biomarkers for predicting clinical responses in patients. Unlicensed NK cells, defined as NK cells lacking expression of an inhibitory KIR for self-HLA class I ligands, are hyporesponsive in steady state, but are potent effectors in inflammatory conditions. We hypothesized that antitumor antibodies such as rituximab can overcome NK-cell dependence on licensing, making unlicensed NK cells important for clinical responses. Here, we examined the influences of variations in KIR and HLA class I alleles on in vitro responses to rituximab. We tested the clinical significance in a cohort of patients with follicular lymphoma treated with rituximab-containing mAb combinations, and show that rituximab triggers responses from all NK-cell populations regardless of licensing. Neither IL2 nor accessory cells are required for activating unlicensed NK cells, but both can augment rituximab-mediated ADCC. Moreover, in 101 patients with follicular lymphoma treated with rituximab-containing mAb combinations, a “missing ligand” genotype (predictive of unlicensed NK cells) is associated with a higher rate of progression-free survival. Our data suggest that the clinical efficacy of rituximab may be driven, in part, by its ability to broaden the NK-cell repertoire to include previously hyporesponsive, unlicensed NK cells. A “missing ligand” KIR and HLA class I genotype may be predictive of this benefit and useful for personalizing treatment decisions in lymphomas and other tumors. Cancer Immunol Res; 2(9); 878–89. ©2014 AACR.

KIR and HLA Genotypes Predictive of Low-Affinity Interactions Are Associated with Lower Relapse in Autologous Hematopoietic Cell Transplantation for Acute Myeloid Leukemia

Killer cell Ig–like receptors (KIRs) bind cognate HLA class I ligands with distinct affinities, affecting NK cell licensing and inhibition. We hypothesized that differences in KIR and HLA class I genotypes predictive of varying degrees of receptor–ligand binding affinities influence clinical outcomes in autologous hematopoietic cell transplantation (AHCT) for acute myeloid leukemia (AML). Using genomic DNA from a homogeneous cohort of 125 AML patients treated with AHCT, we performed KIR and HLA class I genotyping and found that patients with a compound KIR3DL1+ and HLA-Bw4-80Thr+, HLA-Bw4-80Ile– genotype, predictive of low-affinity interactions, had a low incidence of relapse, compared with patients with a KIR3DL1+ and HLA-Bw4-80Ile+ genotype, predictive of high-affinity interactions (hazard ratio [HR], 0.22; 95% confidence interval [CI], 0.06–0.78; p = 0.02). This effect was influenced by HLA-Bw4 copy number, such that relapse progressively increased with one copy of HLA-Bw4-80Ile (HR, 1.6; 95% CI, 0.84–3.1; p = 0.15) to two to three copies (HR, 3.0; 95% CI, 1.4–6.5; p = 0.005) and progressively decreased with one to two copies of HLA-Bw4-80Thr (p = 0.13). Among KIR3DL1+ and HLA-Bw4-80Ile+ patients, a predicted low-affinity KIR2DL2/3+ and HLA-C1/C1 genotype was associated with lower relapse than a predicted high-affinity KIR2DL1+ and HLA-C2/C2 genotype (HR, 0.25; 95% CI, 0.09–0.73; p = 0.01). Similarly, a KIR3DL1+ and HLA-Bw4-80Thr+, HLA-Bw4-80Ile– genotype, or lack of KIR3DL1+ and HLA-Bw4-80Ile+ genotype, rescued KIR2DL1+ and HLA-C2/C2 patients from high relapse (p = 0.007). These findings support a role for NK cell graft-versus-leukemia activity modulated by NK cell receptor–ligand affinities in AHCT for AML.

Delayed hematopoietic recovery after auto-SCT in patients receiving arsenic trioxide-based therapy for acute promyelocytic leukemia: a multi-center analysis.

A potential link between arsenic (ATO)-based therapy and delayed hematopoietic recovery after autologous hematopoietic SCT (HSCT) for acute promyelocytic leukemia (APL) has previously been reported. We retrospectively reviewed the clinical histories of 58 patients undergoing autologous HSCT for APL at 21 institutions in the United States and Japan. Thirty-three (56%) of the patients received ATO-based therapy prior to stem cell collection. Delayed neutrophil engraftment occurred in 10 patients (17%): 9 of the 10 patients (90%) received prior ATO (representing 27% of all ATO-treated patients), compared with 1 of the 10 patients (10%) not previously treated with ATO (representing 4% of all ATO-naïve patients; P<0.001). Compared with ATO-naïve patients, ATO-treated patients experienced significantly longer times to ANC recovery (median 12 days vs 9 days, P<0.001). In multivariate analysis, the only significant independent predictor of delayed neutrophil engraftment was prior treatment with ATO (hazard ratio 4.87; P<0.001). Of the available stem cell aliquots from APL patients, the median viable post-thaw CD34+ cell recovery was significantly lower than that of cryopreserved autologous stem cell products from patients with non-APL AML. Our findings suggest that ATO exposure prior to CD34+ cell harvest has deleterious effects on hematopoietic recovery after autologous HSCT.

Licensing delineates helper and effector NK cell subsets during viral infection

Natural killer (NK) cells can be divided into phenotypic subsets based on expression of receptors that bind self-MHC-I molecules, a concept termed licensing or education. Here we show NK cell subsets with different migratory, effector, and immunoregulatory functions in dendritic cell and antigen (ag)-specific CD8+ T cell responses during influenza and murine cytomegalovirus infections. Shortly after infection, unlicensed NK cells localized in draining lymph nodes and produced GM-CSF, which correlated with the expansion and activation of dendritic cells, and resulted in greater and sustained ag-specific T cell responses. In contrast, licensed NK cells preferentially migrated to infected tissues and produced IFN-γ. Importantly, human NK cell subsets exhibited similar phenotypic characteristics. Collectively, our studies demonstrate a critical demarcation between the functions of licensed and unlicensed NK cell subsets, with the former functioning as the classical effector subset and the latter as the stimulator of adaptive immunity helping to prime immune responses.

Hematopoietic cell transplantation comorbidity index (HCT-CI) is predictive of adverse events and overall survival in older allogeneic transplant recipients

OBJECTIVES Our goal was to evaluate the ability of the hematopoietic cell transplantation comorbidity index (HCT-CI) to predict outcomes after allogeneic stem cell transplant (SCT) within the context of an older patient population, where multiple comorbidities are common. MATERIALS AND METHODS We performed a retrospective cohort study of SCT patients ≥50years of age at our institution, identifying 59 patients with complete HCT-CI data collected prospectively. RESULTS HCT-CI category distribution in our sample was disproportionate, with almost half of patients having scores ≥3. High HCT-CI score (≥3 vs <3) was associated with significantly inferior OS (median OS not reached for HCT-CI <3 vs 14months for HCT-CI ≥3; hazard ratio (HR) 2.2, p=0.02). HCT-CI score was a better predictor of OS than age, performance status or conditioning intensity. When adjusted for disease relapse risk, HCT-CI score conferred a worse prognosis in the low risk group (HR 1.43, p=0.03) but not in the intermediate/high risk group (HR 1.08, p=0.65). NRM was low in the total sample (6% at one year) and was not associated with HCT-CI score. Grade 3-4 non-hematologic adverse events within the first 100days after SCT were significantly more common in the higher HCT-CI groups (p=0.02). CONCLUSIONS In our older patient cohort with a high incidence of multiple comorbidities, HCT-CI score ≥3 was significantly associated with OS, particularly in the subset of patients with a low disease relapse risk.

A phase I study of targeted, dose-escalated intravenous busulfan in combination with etoposide as myeloablative therapy for autologous stem cell transplantation in acute myeloid leukemia.

BACKGROUND Busulfan and etoposide have been used as myeloablative therapy for autologous hematopoietic stem cell transplantation (HSCT) in adults with acute myeloid leukemia (AML) for > 20 years. The use of targeted intravenous (I.V.) busulfan has significantly improved the tolerability and efficacy of this regimen. We designed a dose-escalation study to examine the maximum tolerated dose (MTD) of targeted I.V. busulfan with bolus etoposide as preparative therapy for autologous HSCT in AML. PATIENTS AND METHODS In this single-center, phase I study, adult AML patients received I.V. busulfan targeted to either an area under the curve (AUC) of 1250 (cohort 1) or 1400 (cohort 2) μmol/min over 16 doses. Dose adjustments based on plasma pharmacokinetics occurred before doses 2 and 11. Etoposide 60 mg/kg I.V. was administered 24 hours after the last busulfan dose and 3 days before stem cell infusion. RESULTS Twelve patients with intermediate-risk AML in first complete remission were treated. All patients in cohort 1 and 5 patients (83%) in cohort 2 were within 10% of the target AUC. The MTD was not reached, although Grade ≥ 3 mucositis occurred in 3 patients (50%) in cohort 1 and in 4 patients (66%) in cohort 2, limiting further dose escalation. Two-year relapse-free survival was 33% in cohort 1 versus 67% in cohort 2 (P = .08). CONCLUSION Etoposide and targeted, dose-escalated I.V. busulfan as myeloablative therapy for autologous HSCT in AML is safe, with mucositis being the most significant toxicity. A phase II study is warranted to further evaluate the activity and safety of busulfan targeted to AUC 1400 μmol/min.