Isatuximab-Specific Immunofixation Electrophoresis Assay to Remove Interference in Serum M-Protein Measurement in Patients with Multiple Myeloma.

BACKGROUND: Isatuximab, an IgG-kappa (IgGκ) anti-cluster of differentiation 38 (CD38) monoclonal antibody approved for use in patients with relapsed or refractory multiple myeloma (MM), can potentially interfere with the visualization of endogenous monoclonal protein (M-protein) on standard immunofixation electrophoresis (IFE) and lead to inaccurate classification of a patient's response to therapy. The Hydrashift 2/4 isatuximab IFE assay (Hydrashift isatuximab assay) removes isatuximab interference from IFE. Using samples from patients enrolled in clinical trials of isatuximab-based therapy for MM, we demonstrate how the Hydrashift isatuximab assay improves the ability to detect residual M-protein and offer recommendations for when the assay is most useful. METHODS: Samples from 141 patients with a variety of known M-protein isotypes were selected and analyzed by standard IFE and the Hydrashift isatuximab assay. A positive control containing isatuximab was run on every standard IFE and Hydrashift gel. RESULTS: The Hydrashift isatuximab assay reliably shifted the migration of isatuximab in patient samples. Standard IFE was adequate for determining 104 patients' M-protein status, and the Hydrashift isatuximab assay confirmed these results. In samples from 37 patients with a history of IgGκ MM and a single IgGκ band visible on standard IFE near the isatuximab migration site, the Hydrashift isatuximab assay was able to separate isatuximab from endogenous M-protein, identifying residual M-protein in 17 samples and preventing false-positive interpretations of standard IFE in 20 samples. CONCLUSIONS: The Hydrashift isatuximab assay is most useful in patients with known IgGκ MM when a single IgGκ band appears near the isatuximab migration site on standard IFE during isatuximab-based therapy. ClinicalTrials.gov Registration Numbers: NCT03275285 and NCT03319667.

Isatuximab in combination with carfilzomib and dexamethasone in 1q21+ patients with relapsed/refractory multiple myeloma: Long-term outcomes in the Phase 3 IKEMA study.

Gain/amplification of 1q21 (≥3 copies), a chromosomal abnormality frequently observed in multiple myeloma, can negatively affect prognosis, due to its involvement in resistance to anti-myeloma therapy and disease progression. In this updated subgroup analysis of the randomized, Phase 3 IKEMA study (NCT03275285) in relapsed/refractory multiple myeloma (RRMM), we evaluated progression-free survival (PFS) and depth of response with the anti-CD38 antibody isatuximab plus carfilzomib-dexamethasone (Isa-Kd) versus Kd, in 1q21+ patients and related subgroups, at long-term follow-up (44.2 months). Our analysis included patients with 1q21+ (≥3 copies, with/without high-risk chromosomal abnormality [HRCA]), isolated 1q21+ (≥3 copies, without HRCA), gain(1q21) (3 copies, with/without HRCA), and amp(1q21) (≥4 copies, with/without HRCA). PFS benefit was achieved with Isa-Kd versus Kd in patients with 1q21+ (HR 0.58, 95% CI: 0.37-0.92), with isolated 1q21+ (HR 0.49, 95% CI: 0.27-0.92), with gain(1q21), or amp(1q21), consistent with the overall population and prior interim 1q21+ subgroup analyses. Median PFS with Isa-Kd versus Kd was 25.8 versus 16.2 months in 1q21+ patients and 38.2 versus 16.2 months in patients with isolated 1q21+. Clinically meaningful, higher rates of very good partial response or better, complete response or better (≥CR), minimal residual disease (MRD) negativity, and MRD negativity and ≥CR were reached with Isa-Kd versus Kd in patients with 1q21+, isolated 1q21+, gain(1q21), or amp(1q21). In Isa-Kd and Kd, the MRD negativity and ≥CR rate was 29.3% versus 15.4% in 1q21+ patients, 36.2% versus 12.9% in patients with isolated 1q21+, 27.9% versus 13.5% in patients with gain(1q21), and 31.3% versus 20.0% in patients with amp(1q21), respectively. In conclusion, addition of Isa to Kd in triplet combination therapy has shown PFS benefit and deeper responses, compared with Kd, in 1q21+ patients at higher risk of progression, including patients with isolated 1q21+, gain(1q21), and amp(1q21), thus supporting Isa-Kd an effective treatment option for patients with RRMM.

Isatuximab-pomalidomide-dexamethasone versus pomalidomide-dexamethasone in patients with relapsed and refractory multiple myeloma: final overall survival analysis.

The primary and pre-specified updated analyses of ICARIA-MM (NCT02990338) demonstrated improved progression-free survival and a benefit in overall survival (OS) was reported with the addition of isatuximab, an anti-CD38 monoclonal antibody, to pomalidomide-dexamethasone (Pd) in patients with relapsed/refractory multiple myeloma. Here, we report the final OS analysis. This multicenter, randomized, open-label, phase 3 study included patients who had received and failed ≥2 previous therapies, including lenalidomide and a proteasome inhibitor. Between January 10, 2017, and February 2, 2018, 307 patients were randomized (1:1) to isatuximab-pomalidomide- dexamethasone (Isa-Pd; n = 154) or Pd (n = 153), stratified based on age (3). At data cutoff for the final OS analysis after 220 OS events (January 27, 2022), median follow-up duration was 52.4 months. Median OS (95% confidence interval) was 24.6 months (20.3-31.3 months) with Isa-Pd and 17.7 months (14.4-26.2 months) with Pd (hazard ratio = 0.78; 95% CI, 0.59-1.02; 1-sided P = 0.0319). Despite subsequent daratumumab use in the Pd group and its potential benefit on PFS in the first subsequent therapy line, median PFS2 was significantly longer with Isa-Pd vs. Pd (17.5 vs. 12.9 months; log-rank 1-sided P = 0.0091). In this analysis, Isa-Pd continued to be efficacious and well tolerated after follow-up of approximately 52 months, contributing to a clinically meaningful, 6.9-month improvement in median overall survival in patients with relapsed/refractory multiple myeloma.

A sensitive high-resolution mass spectrometry method for quantifying intact M-protein light chains in patients with multiple myeloma.

To determine the disease status and the response to treatment for patients with multiple myeloma, measuring serum M-protein levels is a widely used alternative to invasive punctures to count malignant plasma cells in the bone marrow. However, the quantification of this monoclonal antibody, which varies from patient to patient, poses significant analytical challenges. This paper describes a sensitive and specific mass spectrometry assay that addresses two objectives: to overcome the potential interference of biotherapeutics in the measurement of M-proteins, and to determine the depth of response to treatment by assessing minimal residual disease. After immunocapture of immunoglobulins and free light chains in serum, heavy and light chains were dissociated by chemical reduction and separated by liquid chromatography. M-proteins were analyzed by high-resolution mass spectrometry using a method combining a full MS scan for isotyping and identification and a targeted single ion monitoring scan for quantification. This method was able to discriminate M-protein from the therapeutic antibody in all patient samples analyzed and allowed quantification of M-protein with a LLOQ of 2.0 to 3.5 µg/ml in 5 out of 6 patients. This methodology appears to be promising for assessing minimal residual disease with sufficient sensitivity, specificity, and throughput.

Efficacy and safety of isatuximab plus bortezomib, lenalidomide, and dexamethasone in patients with newly diagnosed multiple myeloma ineligible/with no immediate intent for autologous stem cell transplantation.

Patients with newly diagnosed multiple myeloma (NDMM) ineligible for autologous stem cell transplantation (ASCT) have lower survival rates and may benefit from frontline regimens that include novel agents. This Phase 1b study (NCT02513186) evaluated preliminary efficacy, safety, and pharmacokinetics (PK) of isatuximab, an anti-CD38 monoclonal antibody, combined with bortezomib-lenalidomide-dexamethasone (Isa-VRd) in patients with NDMM ineligible for/with no intent for immediate ASCT. Overall, 73 patients received four 6-week induction cycles of Isa-VRd, then maintenance with Isa-Rd in 4-week cycles. In the efficacy population (n = 71), the overall response rate was 98.6%, with 56.3% achieving a complete response or better (sCR/CR), and 36/71 (50.7%) patients reaching minimal residual disease negativity (10-5 sensitivity). Grade ≥3 treatment-emergent adverse events (TEAEs) occurred in 79.5% (58/73) of patients but TEAEs leading to permanent study treatment discontinuation were reported in 14 (19.2%) patients. Isatuximab PK parameters were within the previously reported range, suggesting that VRd does not alter the PK of isatuximab. These data support additional studies of isatuximab in NDMM, such as the Phase 3 IMROZ study (Isa-VRd vs VRd).

Isatuximab, carfilzomib, and dexamethasone in patients with relapsed multiple myeloma: updated results from IKEMA, a randomized Phase 3 study.

Longer-term outcomes with the anti-CD38 antibody isatuximab in combination with carfilzomib-dexamethasone (Isa-Kd) were evaluated in the randomized Phase 3 trial IKEMA (NCT03275285), in a prespecified, follow-up analysis of progression-free survival (PFS, primary study endpoint), final complete response (CR) using Hydrashift Isa immunofixation assay, minimal residual disease (MRD) negativity, and safety. Enrolled patients had relapsed/refractory multiple myeloma (1-3 prior treatment lines). Isa 10 mg/kg was administered intravenously weekly in cycle 1 then biweekly. Efficacy analyses were performed in the intent-to-treat population (Isa-Kd: n = 179, Kd: n = 123) and safety evaluated in treated patients (Isa-Kd: n = 177, Kd: n = 122). Consistent with the primary interim analysis, the addition of Isa to Kd prolonged PFS (HR 0.58, 95.4% CI: 0.42-0.79; median PFS 35.7 [95% CI: 25.8-44.0] vs 19.2 [95% CI: 15.8-25.0] months). PFS benefit was observed with Isa-Kd across subgroups, including patients with poor prognosis. The stringent CR/CR rate was 44.1% vs 28.5% (odds-ratio: 2.09, 95% CI: 1.26-3.48), the MRD negativity rate 33.5% vs 15.4% (odds-ratio: 2.78, 95% CI: 1.55-4.99) and the MRD negativity CR rate 26.3% vs 12.2%, with Isa-Kd vs Kd. The safety profile of Isa-Kd was similar to that reported in the prior interim analysis. These findings further support Isa-Kd as a standard-of-care treatment for relapsed multiple myeloma patients.Clinical trial information: ClinicalTrials.gov, NCT03275285.

Isatuximab in combination with cemiplimab in patients with relapsed/refractory multiple myeloma: A phase 1/2 study.

BACKGROUND: Given the incurable nature of multiple myeloma (MM), efforts are made to improve the efficacy of anti-CD38 monoclonal antibodies via combinations with other potentially synergistic therapies. This Phase 1/2 trial (NCT03194867) was designed to determine whether cemiplimab (anti-PD-1) enhances the anti-myeloma activity of isatuximab (anti-CD38) in patients with relapsed and refractory multiple myeloma (RRMM), to confirm the feasibility of the combination, determine its efficacy, and further evaluate its safety. METHODS: Patients received isatuximab 10 mg/kg once weekly for 4 weeks followed by every 2 weeks (Isa), or isatuximab 10 mg/kg plus cemiplimab 250 mg every 2 (Isa + CemiQ2W) or every 4 weeks (Isa + CemiQ4W). RESULTS: Overall, 106 patients with RRMM treated with a median of 4 prior lines were included; 25.5% had high-risk cytogenetics, 63.2% were refractory to proteasome inhibitors and immunomodulatory agents, 26.4% were previously exposed to daratumumab, and 84.0% were refractory to their last treatment line. There were no major changes in the safety or pharmacokinetic profile of isatuximab with the addition of cemiplimab. As assessed by investigators, four patients (11.8%) in the Isa arm, nine patients (25.0%) in the Isa + CemiQ2W arm, and eight patients (22.2%) in the Isa + CemiQ4W arm were responders. Though response rates were numerically higher in cemiplimab-containing arms, differences were not statistically significant and did not translate to improved progression-free or overall survival after a median follow-up of 9.99 months. CONCLUSION: Our results suggest a marginal benefit by adding cemiplimab to isatuximab, despite demonstration of target engagement, without additional observed safety issues.

Anti-CD38 monoclonal antibody interference with blood compatibility testing: Differentiating isatuximab and daratumumab via functional epitope mapping.

BACKGROUND: There are two FDA-approved anti-CD38 monoclonal antibodies for treatment of multiple myeloma: isatuximab and daratumumab. Owing to expression of CD38 on reagent red blood cells (RBCs), these antibodies interfere with indirect antiglobulin tests (IATs). We sought to understand differences in such interference by performing binding experiments. STUDY DESIGN AND METHODS: In vitro experiments to compare the binding to RBCs of isatuximab and daratumumab alone or in the presence of a mouse anti-human CD38 antibody (HB-7 or AT13/5) or a nicotinamide adenine dinucleotide-analog CD38 inhibitor were performed and quantified by flow cytometry, imaging, mass spectrometry, surface plasmon resonance, and LigandTracer technologies. Serologic testing was performed on plasma samples spiked with isatuximab or daratumumab. RESULTS: CD38 expressed on RBCs can be directly bound by daratumumab, whereas isatuximab requires a co-factor, such as HB-7, AT13/5, or a CD38 inhibitor, suggesting that the isatuximab epitope on RBCs is masked in vitro. Daratumumab samples more frequently showed interference and had stronger reactions than isatuximab samples. Dithiothreitol treatment was equally effective in mitigating the interference caused by either drug. DISCUSSION: Both isatuximab and daratumumab interfere with IATs but at different magnitudes, reflecting distinct binding to CD38 on RBCs. From the binding studies, we conclude that the isatuximab epitope on RBCs is masked in vitro and binding requires a certain CD38 conformation or co-factor. This circumstance may explain why interference is seen only in a subset of patients receiving isatuximab when compared with interference seen in most patients on daratumumab therapy.

Isatuximab plus carfilzomib and dexamethasone in relapsed multiple myeloma patients with high-risk cytogenetics: IKEMA subgroup analysis.

INTRODUCTION: The presence of high-risk chromosomal abnormalities [t(4;14), del(17p), and t(14;16)] has been linked with inferior outcomes in patients with multiple myeloma (MM). A prespecified interim analysis of the Phase 3 IKEMA study (NCT03275285) demonstrated that isatuximab (Isa) + carfilzomib (K) and dexamethasone (d; Isa-Kd) significantly improved progression-free survival (PFS) versus Kd in patients with relapsed MM. This prespecified subgroup analysis of IKEMA examined efficacy and safety in patients with high-risk cytogenetics. METHODS: High-risk cytogenetics was assessed by central laboratory and patients were classified as high risk if abnormalities were present in ≥1 of the following: del(17p): 50% cutoff; t(4;14), and/or t(14;16): 30% cutoff. RESULTS: Of the randomized patients, 23.5% (Isa-Kd) and 25.2% (Kd) had ≥1 high-risk chromosomal abnormality. A PFS benefit was seen in favor of Isa-Kd for patients with standard-risk (HR 0.440; 95% CI 0.266-0.728) and high-risk cytogenetics (HR 0.724; 95% CI 0.361-1.451). Grade ≥3 treatment-emergent adverse events (TEAEs) were more common with Isa-Kd (85.7%) versus Kd (63.3%) in patients with high-risk cytogenetics; however, the incidence of serious TEAEs (64.3% vs. 66.7%) was similar. CONCLUSIONS: Isa-Kd is a new treatment option for the difficult-to-treat subgroup of patients with relapsed MM and high-risk cytogenetics.

Depth of response and response kinetics of isatuximab plus carfilzomib and dexamethasone in relapsed multiple myeloma.

The IKEMA study (Randomized, Open Label, Multicenter Study Assessing the Clinical Benefit of Isatuximab Combined With Carfilzomib [Kyprolis®] and Dexamethasone Versus Carfilzomib With Dexamethasone in Patients With Relapse and/or Refractory Multiple Myeloma Previously Treated With 1 to 3 Prior Lines; #NCT03275285) was a randomized, open-label, multicenter phase 3 study investigating isatuximab plus carfilzomib and dexamethasone (Isa-Kd) vs Kd in patients with relapsed multiple myeloma. This subanalysis analyzed the depth of response of Isa-Kd vs Kd. The primary end point was progression-free survival (PFS); secondary end points included overall response rate, very good partial response or better (≥VGPR) rate, complete response (CR) rate, and minimal residual disease (MRD) negativity rate (assessed in patients with ≥VGPR by next-generation sequencing at a 10-5 sensitivity level). At a median follow-up of 20.7 months, deeper responses were observed in the Isa-Kd arm vs the Kd arm, with ≥VGPR 72.6% vs 56.1% and CR of 39.7% vs 27.6%, respectively. MRD negativity occurred in 53 (29.6%) of 179 patients in the Isa-Kd arm vs 16 (13.0%) of 123 patients in the Kd arm, with 20.1% (Isa-Kd, 36 of 179 patients) vs 10.6% (Kd, 13 of 123 patients) reaching MRD-negative CR status. Achieving MRD negativity resulted in better PFS in both arms. A positive PFS treatment effect was seen with Isa-Kd in both MRD-negative patients (hazard ratio, 0.578; 95% CI, 0.052-6.405) and MRD-positive patients (hazard ratio, 0.670; 95% CI, 0.452-0.993). Exploratory analysis indicates that both current CR and MRD-negative CR rates are underestimated due to M-protein interference (potential adjusted CR rate, 45.8%; potential adjusted MRD-negative CR rate, 24.0%). In conclusion, there was a clinically meaningful improvement in depth of response with Isa-Kd. The CR rate in Isa-Kd was 39.7%. Mass spectrometry suggests that the potential adjusted CR rate could reach an unprecedented 45.8% of patients treated with Isa-Kd.

Isatuximab monotherapy in patients with refractory T-acute lymphoblastic leukemia or T-lymphoblastic lymphoma: Phase 2 study.

The poor prognosis of acute T-cell lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL) in older adults and patients with relapsed/refractory illness is an unmet clinical need, as there is no defined standard of care and there are few treatment options. Abnormally elevated CD38 expression in T-ALL and T-LBL is associated with tumor expansion and disease development, making CD38 a potential target for anti-T-ALL and T-LBL treatment. Isatuximab is a monoclonal antibody that binds to a specific epitope on CD38. The purpose of the study was to assess the efficacy and safety of isatuximab monotherapy in a phase 2, multicenter, one-arm, open-label study in patients with relapsed or refractory T-ALL or T-LBL (Clinical Trials.gov identifier NCT02999633). The primary endpoint was to assess the efficacy of isatuximab by overall response rate (ORR). An interim analysis based on the efficacy and safety of isatuximab in the first 19 patients enrolled was scheduled, however only 14 patients were enrolled in the study. No patient achieved complete response (CR) or CR with incomplete peripheral recovery. Most patients (11 [78.6%]) developed progressive disease and had progressive disease as their best response. A total of 10 (71.4%) patients had treatment emergent adverse events considered treatment-related, with infusion reactions as the most frequent drug-related TEAE, occurring in 8 (57.1%) patients. Despite the low efficacy of isatuximab in the current study, it is likely that the use of immunotherapy medication in T-ALL will be expanded through logically targeted approaches, together with advances in the design of T-cell therapy and clinical experience and will provide restorative options beyond chemotherapy and targeted treatments.

Validated Method Based on Immunocapture and Liquid Chromatography Coupled to High-Resolution Mass Spectrometry to Eliminate Isatuximab Interference with M-Protein Measurement in Serum.

In multiple myeloma (MM) disease, malignant plasma cells produce excessive quantities of a monoclonal immunoglobulin (Ig), known as M-protein. M-protein levels are measured in the serum of patients with MM using electrophoresis techniques to determine the response to treatment. However, therapeutic monoclonal antibodies, such as isatuximab, may confound signals using electrophoresis assays. We developed a robust assay based on immunocapture and liquid chromatography coupled to high-resolution mass spectrometry (IC-HPLC-HRMS) in order to eliminate this interference. Following immunocapture of Ig and free light chains (LC) in serum, heavy chains (HC) and LC were dissociated using dithiothreitol, sorted by liquid chromatography and analyzed using HRMS (Q-Orbitrap). This method allowed the M-proteins to be characterized and the signals from isatuximab and M-proteins to be discriminated. As M-protein is specific to each patient, no standards were available for absolute quantification. We therefore used alemtuzumab (an IgG kappa mAb) as a surrogate analyte for the semiquantification of M-protein in serum. This assay was successfully validated in terms of selectivity/specificity, accuracy/precision, robustness, dilution linearity, and matrix variability from 10.0 to 200 µg/mL in human serum. This method was used for clinical assessment of samples and eliminated potential interference due to isatuximab when monitoring patients with MM.

Isatuximab for relapsed/refractory multiple myeloma: review of key subgroup analyses from the Phase III ICARIA-MM study.

In the Phase III ICARIA-MM study (NCT02990338), the addition of the anti-CD38 monoclonal antibody isatuximab to pomalidomide and dexamethasone led to increased progression-free survival and improved response rates in patients with relapsed/refractory multiple myeloma. There is an unmet treatment need, particularly among patients with poor prognoses, including those with high-risk cytogenetics, those who have renal impairment, those who are elderly and those who are refractory to prior lines of treatment. In this review, the subgroup analyses from the ICARIA-MM study, representing subpopulations with poor prognostic factors, are discussed. Overall, the addition of isatuximab to pomalidomide and dexamethasone improved progression-free survival and disease response rates across different subgroups, regardless of prognostic factor.

Lay abstract Currently, the majority of patients with multiple myeloma are not cured, and current treatments may not be helpful for patients with poor prognoses, including those with high-risk chromosomal changes, those who have impaired kidney function, those who are elderly and those who are refractory to prior treatments. In this review, we will discuss the benefits of the combination of isatuximab plus pomalidomide and dexamethasone in these difficult-to-treat patients.

Chromosomal 1q21 abnormalities in multiple myeloma: a review of translational, clinical research, and therapeutic strategies.

INTRODUCTION: Multiple myeloma (MM) remains an incurable disease with a median overall survival of approximately 5 years. Gain or amplification of 1q21 (1q21+) occurs in around 40% of patients with MM and generally portends a poor prognosis. Patients with MM who harbor 1q21+ are at increased risk of drug resistance, disease progression, and death. New pharmacotherapies with novel modes of action are required to overcome the negative prognostic impact of 1q21+. Areas covered: This review discusses the detection, biology, prognosis, and therapeutic targeting of 1q21+ in newly diagnosed and relapsed MM. Patients with MM and 1q21+ tend to present with higher tumor burden, greater end-organ damage, and more co-occurring high-risk cytogenetic abnormalities than patients without 1q21+. The chromosomal rearrangements associated with 1q21+ result in dysregulation of genes involved in oncogenesis. Identification and characterization of the 1q21+ molecular targets are needed to inform on prognosis and treatment strategy. Clinical trial data are emerging that addition of isatuximab to combination therapies may improve outcomes in patients with 1q21+ MM. Expert opinion: In the next 5 years, the results of ongoing research and trials are likely to focus on the therapeutic impact and treatment decisions associated with 1q21+ in MM.

Individualized genetic makeup that controls natural killer cell function influences the efficacy of isatuximab immunotherapy in patients with multiple myeloma.

BACKGROUND: Phase IIb clinical trial with isatuximab (Isa)-lenalidomide (Len)-dexamethasone (Dex) showed an improved progression-free survival (PFS) in patients with relapsed or refractory multiple myeloma (RRMM), but the efficacy varied by patient. Antibody-dependent cell-mediated cytotoxicity (ADCC) by natural killer (NK) cells plays a crucial role in arbitrating antitumor activities of therapeutic-antibodies. We tested if patient-specific genetic makeup known to set NK cell functional threshold influence response to Isa-Len-Dex therapy. METHODS: We characterized 57 patients with RRMM receiving Isa-Len-Dex for polymorphisms of killer-cell immunoglobulin-like receptors (KIR), human leukocyte antigen (HLA) class I, and FCGR3A loci. In vitro ADCC assay, coincubating primary NK cells expressing specific KIR repertoire with multiple myeloma cell lines (MM cells) expressing selected HLA class I ligands, was used to confirm the identified genetic correlatives of clinical response. RESULTS: Patients with KIR3DL2+ and its cognate-ligand HLA-A3/11+ had superior PFS than patients missing this combination (HR=0.43; p=0.02), while patients carrying KIR2DL1+ and HLA-C2C2+ compared with to patients missing this pair showed short PFS (HR=3.54; p=0.05). Patients with KIR3DL2+ and HLA-A3/11+ plus high-affinity FCGR3A-158V allele showed the most prolonged PFS (HR=0.35; p=0.007). Consistent with these clinical data, mechanistic experiments demonstrated that NK cells expressing KIR3DL2 trigger greater ADCC when MM cells express HLA-A3/11. Inversely, NK cells expressing KIR2DL1 do not kill if MM cells express the HLA-C2C2 ligand. NK cells expressing high-affinity FCGR3A-158VV-induced greater ADCC compared with those with low-affinity FCGR3A-158FF. CONCLUSIONS: Our results suggest that KIR3DL2+ and HLA-A3/11+ with FCGR3A-158V markers lead to enhanced Isa-dependent NK-mediated cytolysis against MM cells and results in improved PFS in patients with RRMM treated by Isa-Len-Dex. Moreover, the presence of KIR2DL1+ and HLA-C2C2+ identifies patients who may have a lower response to Isa-Len-Dex therapy linked to a reduced NK-mediated ADCC. These biomarkers could potentially identify, via precision medicine, patients more likely to respond to Isa-Len-Dex immunotherapy. TRIAL REGISTRATION NUMBER: NCT01749969.

Elucidating Prostate Cancer Behaviour During Treatment via Low-pass Whole-genome Sequencing of Circulating Tumour DNA.

BACKGROUND: Better blood tests to elucidate the behaviour of metastatic castration-resistant prostate cancer (mCRPC) are urgently needed to drive therapeutic decisions. Plasma cell-free DNA (cfDNA) comprises normal and circulating tumour DNA (ctDNA). Low-pass whole-genome sequencing (lpWGS) of ctDNA can provide information on mCRPC behaviour. OBJECTIVE: To validate and clinically qualify plasma lpWGS for mCRPC. DESIGN, SETTING, AND PARTICIPANTS: Plasma lpWGS data were obtained for mCRPC patients consenting to optional substudies of two prospective phase 3 trials (FIRSTANA and PROSELICA). In FIRSTANA, chemotherapy-naïve patients were randomised to treatment with docetaxel (75 mg/m2) or cabazitaxel (20 or 25 mg/m2). In PROSELICA, patients previously treated with docetaxel were randomised to 20 or 25 mg/m2 cabazitaxel. lpWGS data were generated from 540 samples from 188 mCRPC patients acquired at four different time points (screening, cycle 1, cycle 4, and end of study). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: lpWGS data for ctDNA were evaluated for prognostic, response, and tumour genomic measures. Associations with response and survival data were determined for tumour fraction. Genomic biomarkers including large-scale transition (LST) scores were explored in the context of prior treatments. RESULTS AND LIMITATIONS: Plasma tumour fraction was prognostic for overall survival in univariable and stratified multivariable analyses (hazard ratio 1.75, 95% confidence interval 1.08-2.85; p = 0.024) and offered added value compared to existing biomarkers (C index 0.722 vs 0.709; p = 0.021). Longitudinal changes were associated with drug response. PROSELICA samples were enriched for LSTs (p = 0.029) indicating genomic instability, and this enrichment was associated with prior abiraterone and enzalutamide treatment but not taxane or radiation therapy. Higher LSTs were correlated with losses of RB1/RNASEH2B, independent of BRCA2 loss. CONCLUSIONS: Plasma lpWGS of ctDNA describes CRPC behaviour, providing prognostic and response data of clinical relevance. The added prognostic value of the ctDNA fraction over established biomarkers should be studied further. PATIENT SUMMARY: We studied tumour DNA in blood samples from patients with prostate cancer. We found that levels of tumour DNA in blood were indicative of disease prognosis, and that changes after treatment could be detected. We also observed a "genetic scar" in the results that was associated with certain previous treatments. This test allows an assessment of tumour activity that can complement existing tests, offer insights into drug response, and detect clinically relevant genetic changes.