Loss of CD20 expression as a mechanism of resistance to mosunetuzumab in relapsed/refractory B-cell lymphomas.

ABSTRACT: CD20 is an established therapeutic target in B-cell malignancies. The CD20 × CD3 bispecific antibody mosunetuzumab has significant efficacy in B-cell non-Hodgkin lymphomas (NHLs). Because target antigen loss is a recognized mechanism of resistance, we evaluated CD20 expression relative to clinical response in patients with relapsed and/or refractory NHL in the phase 1/2 GO29781 trial investigating mosunetuzumab monotherapy. CD20 was studied using immunohistochemistry (IHC), RNA sequencing, and whole-exome sequencing performed centrally in biopsy specimens collected before treatment at predose, during treatment, or upon progression. Before treatment, most patients exhibited a high proportion of tumor cells expressing CD20; however, in 16 of 293 patients (5.5%) the proportion was <10%. Analyses of paired biopsy specimens from patients on treatment revealed that CD20 levels were maintained in 29 of 30 patients (97%) vs at progression, where CD20 loss was observed in 11 of 32 patients (34%). Reduced transcription or acquisition of truncating mutations explained most but not all cases of CD20 loss. In vitro modeling confirmed the effects of CD20 variants identified in clinical samples on reduction of CD20 expression and missense mutations in the extracellular domain that could block mosunetuzumab binding. This study expands the knowledge about the occurrence of target antigen loss after anti-CD20 therapeutics to include CD20-targeting bispecific antibodies and elucidates mechanisms of reduced CD20 expression at disease progression that may be generalizable to other anti-CD20 targeting agents. These results also confirm the utility of readily available IHC staining for CD20 as a tool to inform clinical decisions. This trial was registered at www.ClinicalTrials.gov as #NCT02500407.

Long-term 3-year follow-up of mosunetuzumab in relapsed or refractory follicular lymphoma after ≥2 prior therapies.

Mosunetuzumab, a CD20xCD3 T-cell engaging bispecific antibody, redirects T cells to eliminate malignant B cells. We present updated efficacy and safety data of a pivotal phase 1/2 study after a median follow-up of 37.4 months in 90 patients with relapsed/refractory (R/R) follicular lymphoma (FL) and ≥2 prior lines of therapy treated with fixed-duration mosunetuzumab. Investigator-assessed complete response (CR) rate and objective response rate (ORR) were 60.0% (95% confidence interval [CI], 49.1-70.2) and 77.8% (95% CI, 67.8-85.9), respectively. Among 70 responders, median duration of response was 35.9 months (95% CI, 20.7-not estimable [NE]). Among 54 patients who achieved CR, 49 remained in CR at the end of treatment; median duration of complete response was not reached (NR) (95% CI, 33.0-NE); Kaplan-Meier-estimated 30-month remission rate was 72.4% (95% CI, 59.2-85.6). Estimated 36-month overall survival (OS) rate was 82.4% (95% CI, 73.8-91.0); median OS was NR (95% CI, NE-NE). Median progression-free survival was 24.0 months (95% CI, 12.0-NE). Median time to CD19+ B-cell recovery was 18.4 months (95% CI, 12.8-25.0) following 8 cycles of mosunetuzumab treatment. No new cytokine release syndrome events or fatal, serious, or Grade ≥3 adverse events were reported. With extended follow-up, mosunetuzumab demonstrated high response rates, durable remissions and manageable safety with no long-term concerns. This supports outpatient mosunetuzumab administration as an off-the-shelf, fixed-duration, safe and effective treatment for patients with R/R FL, including those with high-risk disease. Trial registration: www.clinicaltrials.gov (NCT02500407).

Safety and efficacy of mosunetuzumab, a bispecific antibody, in patients with relapsed or refractory follicular lymphoma: a single-arm, multicentre, phase 2 study.

BACKGROUND: Mosunetuzumab is a CD20 × CD3 T-cell-engaging bispecific monoclonal antibody that redirects T cells to eliminate malignant B cells. In a phase 1 study, mosunetuzumab was well tolerated and active in patients with relapsed or refractory B-cell lymphoma. We, therefore, aimed to evaluate the safety and anti-tumour activity of fixed-duration mosunetuzumab in patients with relapsed or refractory follicular lymphoma who had received two or more previous therapies. METHODS: We conducted a single-arm, multicentre, phase 2 study at 49 centres in seven countries (Australia, Canada, Germany, South Korea, Spain, UK, and USA). All patients were aged 18 years or older with histologically confirmed follicular lymphoma (grade 1-3a) and an Eastern Cooperative Oncology Group performance status of 0-1. Patients had disease that was relapsed or refractory to two or more previous lines of treatment, including an anti-CD20 therapy and an alkylating agent. Intravenous mosunetuzumab was administered in 21-day cycles with cycle 1 step-up dosing: 1 mg on cycle 1 day 1, 2 mg on cycle 1 day 8, 60 mg on cycle 1 day 15 and cycle 2 day 1, and 30 mg on day 1 of cycle 3 and onwards. Patients with a complete response by investigator assessment using the International Harmonisation Project criteria completed treatment after cycle 8, whereas patients with a partial response or stable disease continued treatment for up to 17 cycles. The primary endpoint was independent review committee-assessed complete response rate (as best response) in all enrolled patients; the primary efficacy analysis compared the observed IRC-assessed complete response rate with a 14% historical control complete response rate in a similar patient population receiving the pan class I PI3K inhibitor copanlisib. Safety was assessed in all enrolled patients. This study is registered with ClinicalTrials.gov, number NCT02500407, and is ongoing. FINDINGS: Between May 2, 2019, and Sept 25, 2020, we enrolled 90 patients. As of the data cutoff date (Aug 27, 2021), the median follow-up was 18·3 months (IQR 13·8-23·3). According to independent review committee assessment, a complete response was recorded in 54 patients (60·0% [95% CI 49·1-70·2]). The observed complete response rate was significantly higher than the historical control complete response rate with copanlisib of 14% (p<0·0001), thereby meeting the primary study endpoint. Cytokine release syndrome was the most common adverse event (40 [44%] of 90 patients) and was predominantly grade 1 (23 [26%] of 90) and grade 2 (15 [17%]), and primarily confined to cycle 1. The most common grade 3-4 adverse events were neutropenia or neutrophil count decreased (24 [27%] of 90 patients), hypophosphataemia (15 [17%]), hyperglycaemia (seven [8%]), and anaemia (seven [8%]). Serious adverse events occurred in 42 (47%) of 90 patients. No treatment-related grade 5 (ie, fatal) adverse event occurred. INTERPRETATION: Fixed-duration mosunetuzumab has a favourable safety profile and induces high rates of complete remissions, allowing potential administration as an outpatient regimen, in patients with relapsed or refractory follicular lymphoma and two or more previous therapies. FUNDING: F Hoffmann-La Roche and Genentech.

Prognostic mutational subtyping in de novo diffuse large B-cell lymphoma.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease defined using a number of well-established molecular subsets. Application of non-negative matrix factorization (NMF) to whole exome sequence data has previously been used to identify six distinct molecular clusters in DLBCL with potential clinical relevance. In this study, we applied NMF-clustering to targeted sequencing data utilizing the FoundationOne Heme® panel from the Phase III GOYA (NCT01287741) and Phase Ib/II CAVALLI studies (NCT02055820) in de novo DLBCL. Biopsy samples, survival outcomes, RNA-Seq and targeted exome-sequencing data were available for 423 patients in GOYA (obinutuzumab [G]-cyclophosphamide, doxorubicin, vincristine, and prednisone [CHOP] vs rituximab [R]-CHOP) and 86 patients in CAVALLI (venetoclax+[G/R]-CHOP). RESULTS: When the NMF algorithm was applied to samples from the GOYA study analyzed using a comprehensive genomic profiling platform, four of the six groups previously reported were observed: MYD88/CD79B, BCL2/EZH2, NOTCH2/TNFAIP3, and no mutations. Mutation profiles, cell-of-origin subset distributions and clinical associations of MYD88/CD79B and BCL2/EZH2 groups were similar to those described in previous NMF studies. In contrast, application of NMF to the CAVALLI study yielded only three; MYD88/CD79B-, BCL2/EZH2-like clusters, and a no mutations group, and there was a trend towards improved outcomes for BCL2/EZH2 over MYD88/CD79B. CONCLUSIONS: This analysis supports the utility of NMF used in conjunction with targeted sequencing platforms for identifying patients with different prognostic subsets. The observed trend for improved overall survival in the BCL2/EZH2 group is consistent with the mechanism of action of venetoclax, suggesting that targeting sequencing and NMF has potential for identifying patients who are more likely to gain benefit from venetoclax therapy.

Polatuzumab vedotin in combination with immunochemotherapy in patients with previously untreated diffuse large B-cell lymphoma: an open-label, non-randomised, phase 1b-2 study.

BACKGROUND: Polatuzumab vedotin, an antibody-drug conjugate targeting the CD79b component of the B-cell receptor, has demonstrated activity as a single agent and in combination with rituximab in relapsed or refractory diffuse large B-cell lymphoma. In this study, we evaluated the safety and preliminary activity of polatuzumab vedotin in combination with rituximab or obinutuzumab and cyclophosphamide, doxorubicin, and prednisone (CHP) in patients with previously untreated diffuse large B-cell lymphoma. METHODS: This was an open-label, non-randomised study composed of a phase 1b dose escalation and a phase 2 dose expansion at 11 hospitals and health centres in the USA and France. Patients aged 18 years or older with B-cell non-Hodgkin lymphoma were eligible. Exclusion criteria included peripheral neuropathy with grade greater than 1, major surgery within 4 weeks before enrolment, known CNS involvement of lymphoma, and uncontrolled heart disease. Phase 1b dose escalation had a three-plus-three design and established the recommended phase 2 dose. Phase 2 expansion evaluated the recommended phase 2 dose of polatuzumab vedotin in patients with newly diagnosed diffuse large B-cell lymphoma with an International Prognostic Index (IPI) of 2-5. Patients received cyclophosphamide 750 mg/m2 on day 1 intravenously, doxorubicin 50 mg/m2 on day 1 intravenously, and prednisone 100 mg once daily on days 1-5 of each 21-day cycle orally (CHP), plus either rituximab 375 mg/m2 intravenously on day 1 of each cycle (R-CHP) or obinutuzumab 1000 mg intravenously on days 1, 8, and 15 of cycle 1 and on day 1 of the following cycles (G-CHP). Polatuzumab vedotin was administered on day 2 of cycles 1 and 2, and on day 1 of the following cycles at 1·0-2·4 mg/kg during the escalation phase and at the recommended phase 2 dose during the expansion phase. Treatment could last six or eight cycles, depending on investigator preference. The primary endpoints of the study were safety and tolerability, and determination of the maximum tolerated dose (or recommended phase 2 dose) of polatuzumab vedotin. All endpoints were analysed per protocol in the safety evaluable population, defined as all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, number NCT01992653. FINDINGS: Between Dec 4, 2013, and July 26, 2016, 85 patients were enrolled. 82 patients were included in the safety and activity evaluable populations, 25 in phase 1b and 57 in phase 2. In light of information from other studies using polatuzumab vedotin reported during this study, in which the safety profile associated with exposure to polatuzumab vedotin at doses higher than 1·8 mg/kg every 3 weeks was not outweighed by any clinical benefit, the recommended phase 2 dose was set to 1·8 mg/kg in the R-CHP cohort and no higher doses were explored in this study. 66 patients with newly diagnosed diffuse large B-cell lymphoma received the polatuzumab vedotin recommended phase 2 dose (45 R-CHP; 21 G-CHP). In 66 patients with diffuse large B-cell lymphoma who received the recommended phase 2 dose, the most common adverse events of grade 3 or worse were neutropenia (20 [30%]), febrile neutropenia (12 [18%]), and thrombocytopenia (six [9%]). Among the 70 patients (any histology) who received the recommended phase 2 dose, 19 (27%) had grade 1 peripheral neuropathy, eight (11%) grade 2, and two (3%) grade 3. Four deaths were reported during follow-up: two treatment-related (one complication of atrial fibrillation and one septic shock) and two due to disease progression. As of the cutoff date of Dec 29, 2017, median follow-up time was 21·5 months (IQR 16·7-24·3) for the untreated diffuse large B-cell lymphoma cohort treated at the polatuzumab vedotin recommended phase 2 dose. 59 (89%) patients achieved an overall response at end of treatment (51 [77%] patients had a complete response, and eight [12%] patients had a partial response). INTERPRETATION: The safety of incorporating polatuzumab vedotin to R-CHP or G-CHP was as expected and managable. Preliminary clinical activity in newly diagnosed diffuse large B-cell lymphoma seems promising and encouraged a phase 3 trial comparing polatuzumab vedotin with R-CHP to R-CHOP. FUNDING: F Hoffmann-La Roche/Genentech.

Widespread potential for growth-factor-driven resistance to anticancer kinase inhibitors.

Mutationally activated kinases define a clinically validated class of targets for cancer drug therapy. However, the efficacy of kinase inhibitors in patients whose tumours harbour such alleles is invariably limited by innate or acquired drug resistance. The identification of resistance mechanisms has revealed a recurrent theme­the engagement of survival signals redundant to those transduced by the targeted kinase. Cancer cells typically express multiple receptor tyrosine kinases (RTKs) that mediate signals that converge on common critical downstream cell-survival effectors­most notably, phosphatidylinositol-3-OH kinase (PI(3)K) and mitogen-activated protein kinase (MAPK). Consequently, an increase in RTK-ligand levels, through autocrine tumour-cell production, paracrine contribution from tumour stroma or systemic production, could confer resistance to inhibitors of an oncogenic kinase with a similar signalling output. Here, using a panel of kinase-'addicted' human cancer cell lines, we found that most cells can be rescued from drug sensitivity by simply exposing them to one or more RTK ligands. Among the findings with clinical implications was the observation that hepatocyte growth factor (HGF) confers resistance to the BRAF inhibitor PLX4032 (vemurafenib) in BRAF-mutant melanoma cells. These observations highlight the extensive redundancy of RTK-transduced signalling in cancer cells and the potentially broad role of widely expressed RTK ligands in innate and acquired resistance to drugs targeting oncogenic kinases.

Phase Ib study of duligotuzumab (MEHD7945A) plus cisplatin/5-fluorouracil or carboplatin/paclitaxel for first-line treatment of recurrent/metastatic squamous cell carcinoma of the head and neck.

BACKGROUND: This open-label, multicenter, phase Ib study assessed the safety and preliminary activity of duligotuzumab, a dual-action antibody that blocks ligand binding to human epidermal growth factor receptor 3 (HER3) and epidermal growth factor receptor, in combination with chemotherapy, in the first-line treatment of patients with recurrent/metastatic squamous cell cancer of the head and neck. METHODS: On day 1, duligotuzumab at a dose of 1650 mg intravenously was combined with cisplatin at a dose of 100 mg/m2 and 5-fluorouracil at a dose of 1000 mg/m2 /day on days 1 to 4 in treatment arm A, or carboplatin (area under the curve, 6 mg/mL/min) and paclitaxel (at a dose of 200 mg/m2 ) in treatment arm B. Up to 6 cycles (21 days/cycle) were followed by duligotuzumab maintenance until disease progression or intolerable toxicity occurred. RESULTS: Nine patients in arm A and 15 patients in arm B received a median of 6 cycles of chemotherapy, and a median of 11 cycles (arm A) and 9 cycles (arm B) of duligotuzumab. Dose-limiting toxicities occurred in 3 patients in arm A and 1 patient in arm B. Grade ≥ 3 treatment-related adverse events (graded according to graded according to National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]) in ≥ 3 patients were neutropenia (5 patients), hypokalemia (4 patients), dehydration (3 patients), anemia (3 patients), and diarrhea (3 patients) in arm A, and neutropenia (8 patients), anemia (5 patients), febrile neutropenia (4 patients), leukopenia (3 patients), thrombocytopenia (3 patients), and hypomagnesemia (3 patients) in arm B. The chemotherapy dose was reduced in 19 of 24 patients. Sixteen patients (67%) demonstrated objective responses regardless of human papillomavirus status or neuregulin 1 (NRG1) mRNA expression (arm A: 2 confirmed complete responses and 4 confirmed partial responses; arm B: 2 confirmed complete responses and 8 confirmed partial responses). CONCLUSIONS: Duligotuzumab in combination with cisplatin/5-fluorouracil or carboplatin/paclitaxel demonstrated encouraging activity in patients with recurrent/metastatic squamous cell cancer of the head and neck; an association with increased frequency and severity of select adverse events relative to historical data was suggestive of the potentiation of chemotherapy-related adverse events. Cancer 2016;122:3803-3811. © 2016 American Cancer Society.

T cell-Dependent Bispecific Therapy Enhances Innate Immune Activation and Antibody-Mediated Killing.

T cell-retargeting therapies have transformed the therapeutic landscape for hematologic diseases. T cell-dependent bispecific antibodies (TDB) function as conditional agonists that induce a polyclonal T-cell response, resulting in target cell destruction and cytokine release. The relationship between this response and its effects on surrounding innate immune populations has not been fully explored. Here we show that treatment with mosunetuzumab in patients results in natural killer (NK) cell activation in the peripheral blood. We modeled this phenomenon in vitro and found that TDB-mediated killing activated NK cells, increasing NK function and antibody-dependent cellular cytotoxicity (ADCC), and enhanced the capability of macrophages to perform antibody-dependent cellular phagocytosis (ADCP). This enhancement was triggered by cytokines released through TDB treatment, with IL2 and IFNγ being major drivers for increased ADCC and ADCP, respectively. Surprisingly, cytolytic ability could be further augmented through neutralization of IL10 for NK cells and TNFα for macrophages. Finally, we showed that TDB treatment enhanced the efficacy of Fc-driven killing to an orthogonal solid tumor target in vivo. These results provide rationale for novel antibody therapy combinations that take advantage of both adaptive and innate immune responses.

A Novel Step-Up Dosage Regimen for Enhancing the Benefit-to-Risk Ratio of Mosunetuzumab in Relapsed or Refractory Follicular Lymphoma.

Mosunetuzumab, a T-cell engaging bispecific antibody targeting CD20xCD3, is approved for treating relapsed/refractory follicular lymphoma. This research supports the approved intravenous clinical dose regimen, summarizing the exposure-response relationships for clinical safety and efficacy. A population pharmacokinetic model and Emax logistic regression exposure-response models for safety and efficacy were developed using data from 439 patients with relapsed/refractory non-Hodgkin lymphoma and 159 patients with relapsed/refractory follicular lymphoma, respectively, from a Phase I/II study (NCT02500407). Data from 0.2 to 60 mg across fixed dosing (Cohort A) and Cycle 1 step-up dosing (Cohort B) were used. Exposure-response models, using two-cycle area-under-the-concentration curve (AUC0-42) as the primary exposure endpoint, accurately depicted the complete response and objective response rate data across a 600-fold AUC0-42 range. The approved clinical dose regimen of 1/2/60/30 mg achieved near-maximal efficacy, with model-estimated CR and ORR (90% confidence interval) of 63.1% (49.7-75.0) and 79.1% (69.1-87.7), respectively. The exposure-response analysis for Grade ≥ 2 cytokine release syndrome identified receptor occupancy (%) within the first two cycles as a driver, with CRS dissipating beyond the first dosing cycle. No exposure-dependent increases were observed for other serious adverse events, including neutropenia and infections. The approved intravenous step-up dose regimen (i.e., step doses of 1 and 2 mg on Day 1 and 8, respectively) mitigated severe CRS risk, allowing safe administration of loading (60 mg) and target doses (30 mg every 3 weeks) to achieve a favorable benefit-risk profile.

Integrative genomic analysis identifies unique immune environments associated with immunotherapy response in diffuse large B cell lymphoma.

Most diffuse large B-cell lymphoma (DLBCL) patients treated with bispecific antibodies (BsAb) or chimeric antigen receptor (CAR) T cells fail to achieve durable treatment responses, underscoring the need for a deeper understanding of mechanisms that regulate the immune environment and response to treatment. Here, an integrative, multi-omic approach was employed to characterize DLBCL immune environments, which effectively segregated DLBCLs into four quadrants - termed DLBCL-immune quadrants (IQ) - defined by cell-of-origin and immune-related gene set expression scores. Recurrent genomic alterations were enriched in each IQ, suggesting that lymphoma cell-intrinsic alterations contribute to orchestrating unique DLBCL immune environments. In relapsed/refractory DLBCL patients, DLBCL-IQ assignment correlated significantly with clinical benefit with the CD20 x CD3 BsAb, mosunetuzumab, but not with CD19-directed CAR T cells. DLBCL-IQ provides a new framework to conceptualize the DLBCL immune landscape and uncovers the differential impact of the endogenous immune environment on outcomes to BsAb and CAR T cell treatment.

Mosunetuzumab monotherapy is active and tolerable in patients with relapsed/refractory diffuse large B-cell lymphoma.

As part of a phase 1 or 2 study, this single-arm expansion cohort established the efficacy and safety of mosunetuzumab monotherapy in patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) (received ≥2 previous lines of therapy). Intravenous mosunetuzumab was administered with cycle (C) 1 step-up dosing for cytokine release syndrome (CRS) mitigation: C1 day (D) 1: 1 mg; C1D8 2 mg; C1D15 and C2D1: 60 mg; C3 + D1: 30 mg. Hospitalization was not mandatory. Patients with complete response (CR) completed treatment after C8; those with partial response or stable disease continued treatment for a total of 17 cycles. The primary end point was CR rate (best response), assessed against a historical control CR rate (20%) by independent review facility. Eighty-eight patients (73.9% de novo DLBCL; 26.1% transformed follicular lymphoma) were enrolled; all had received previous anthracycline and anti-CD20 therapy. Overall response and CR rates were 42.0% (95% confidence interval [CI], 31.6-53.1) and 23.9% (95% CI, 15.4-34.1), respectively; CR rate did not reach statistical significance vs the historical control (P = .36). Median time to first response was 1.4 months. Median progression-free survival was 3.2 months (95% CI, 2.2-5.3). The CR rate in 26 patients who received previous chimeric antigen receptor T-cell (CAR-T) therapy was 12%. CRS was one of the most common adverse events (26.1% of patients); predominantly grade 1 to 2 and primarily in C1. Four patients (4.5%) discontinued mosunetuzumab owing to adverse events. Mosunetuzumab demonstrated notable efficacy and a manageable safety profile in patients with R/R DLBCL, including those previously treated with CAR-Ts. This trial was registered at www.clinicaltrials.gov as #NCT02500407.

Combination of Atezolizumab and Obinutuzumab in Patients with Relapsed/Refractory Follicular Lymphoma and Diffuse Large B-Cell Lymphoma: Results from a Phase 1b Study.

BACKGROUND: This was an open-label, phase 1b study assessing the safety, tolerability, preliminary efficacy and pharmacokinetics of the combination of atezolizumab and obinutuzumab in patients with relapsed/refractory follicular lymphoma (FL) or diffuse large B-cell lymphoma (DLBCL). There is a mechanistic rationale suggesting that this combination may enhance recruitment of both innate and adaptive immunity and be effective against CD20+ B-cell malignancies. MATERIALS AND METHODS: The study consisted of a safety evaluation stage and an expansion stage. Patients received obinutuzumab 1000 mg intravenously (IV) in cycle (C) 1, obinutuzumab plus atezolizumab 1200 mg IV for C2-8, and atezolizumab only from C9. Primary endpoints were to identify a recommended phase 2 dose (RP2D) for atezolizumab, and safety and tolerability in the safety and expansion stages. RESULTS: A total of 49 patients were enrolled (FL, n = 26; DLBCL, n = 23), with a median of 2 prior lines of treatment. The RP2D for atezolizumab was 1200 mg IV every 3 weeks. Adverse events reported in ≥ 20% of patients were fatigue (15 patients [31%]), nausea (13 patients [27%]), cough, and diarrhea (10 patients [20%] each). Objective response rate was 54% in the FL cohort (complete response [CR] rate: 23%) and 17% in the DLBCL cohort (CR: 4%). Median progression-free survival was 9 months for FL and 3 months for DLBCL. Median overall survival was not estimable for FL and 9 months for DLBCL. CONCLUSION: The combination of obinutuzumab and atezolizumab was determined to be safe and tolerable, with no new toxicities observed.

Combination of Atezolizumab and Tazemetostat in Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma: Results From a Phase Ib Study.

BACKGROUND: The combination of atezolizumab, a monoclonal antibody that targets programmed death-ligand 1 (PD-L1) and inhibits the interaction between PD-L1 and its receptors, and tazemetostat, an EZH2 inhibitor, may lead to selective epigenetic reprogramming, alter the tumor microenvironment, and provide additive or synergistic response to patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL). MATERIALS AND METHODS: This was an open-label, phase Ib study assessing the safety, tolerability, and preliminary efficacy of atezolizumab plustazemetostat in patients with R/R DLBCL. Atezolizumab (1200 mg) was administered via intravenous (IV) infusion on day 1 of each cycle and tazemetostat (800 mg) was given orally twice daily (BID) on days 1 to 21. Primary endpoints were safety and tolerability, and to identify a recommended phase II dose (RP2D) for atezolizumab. Secondary efficacy endpoints included response rate and duration of response. RESULTS: A total of 43 patients were enrolled, receiving a median of 3 prior lines of treatment (range: 1-9). The RP2D for atezolizumab was 1200 mg IV infusion every 3 weeks in combination with tazemetostat 800 mg BID. At the RP2D, adverse events reported in ≥20% patients were anemia(11 patients [26%]), fatigue (10 patients [23%]), and nausea (10 patients [23%]). Overall response rate was 16% (complete response rate: 7%). Median progression-free survival was 2 months (range: 0-24) and median overall survival was 13 months (range: 1-29). CONCLUSIONS: The combination of atezolizumab and tazemetostat was determined to be safe and tolerable. However, anti-tumor activity of the combination was modest.

Anti-CD79B Antibody-Drug Conjugate DCDS0780A in Patients with B-Cell Non-Hodgkin Lymphoma: Phase 1 Dose-Escalation Study.

PURPOSE: Targeting CD79B using antibody-drug conjugates (ADC) is an effective therapeutic strategy in B-cell non-Hodgkin lymphoma (B-NHL). We investigated DCDS0780A, an anti-CD79B ADC with THIOMAB technology (TDC) that consistently conjugates two anti-neoplastic molecules per antibody, in contrast with ADCs with heterogeneous loads. PATIENTS AND METHODS: This phase 1 study enrolled 60 patients with histologically confirmed B-NHL that had relapsed/failed to respond following ≥1 prior treatment regimens; 41 (68%) had diffuse large B-cell lymphoma (DLBCL). Fifty-one patients received DCDS0780A monotherapy once every 3 weeks (0.3-4.8 mg/kg); 9 received combination therapy (3.6-4.8 mg/kg) with rituximab. RESULTS: Fifty-four (90%) patients experienced adverse events related to study drug, the most common of which were blurred vision, fatigue, corneal deposits, neutropenia, nausea, and peripheral neuropathy. 4.8 mg/kg was the highest dose tested and the recommended phase II dose. The pharmacokinetic profile was linear at doses ≥1.2 mg/kg. Response rate in all-treated patients (N = 60) was 47% (n = 28), including 17 complete responses (28%) and 11 partial responses (18%). The median duration of response (15.2 months) was the same for all responders (n = 28) and patients with DLBCL (n = 20). CONCLUSIONS: DCDS0780A as the TDC format for CD79B was tested at higher doses than its ADC counterpart investigated earlier, leading to deep responses. However, dose intensity was limited by ocular toxicities seen at the higher doses indicating that the TDC format was unable, in the current study, to expand the therapeutic index for the CD79B target. The encouraging antitumor activity advocates continuation of investigations into novel ADC technologies.

EGFR over-expression and activation in high HER2, ER negative breast cancer cell line induces trastuzumab resistance.

HER2 is gene amplified or over-expressed in 20-25% of breast cancers resulting in elevated HER2 activation. Trastuzumab (Herceptin), a humanized monoclonal antibody, targets activated HER2 and is clinically effective in HER2-over-expressing breast cancers. However, despite prolonged survival, treated breast cancer patients develop resistance. Resistance to trastuzumab occurs upon inactivation of HER2 regulatory proteins or upon up-regulation of alternative receptors. In particular, elevated levels of EGFR, present in estrogen receptor (ER) positive, trastuzumab-resistant BT-474 xenografts caused, a trastuzumab-resistant phenotype (Ritter et al. Clin Cancer Res 13:4909-4919, 2007). However, the role of EGFR in acquired trastuzumab resistance in ER negative cell models is not well defined. In this study, SKBR3 cell line clones expressing EGFR were generated to examine the role of EGFR over-expression on trastuzumab sensitivity in an, ER-negative breast carcinoma cell line. A stable clone, SKBR3/EGFR (clone 4) expressing moderate levels of EGFR remained sensitive to trastuzumab, whereas a stable clone, SKBR3/EGFR (clone 5) expressing high levels of EGFR, became resistant to trastuzumab. Depletion of EGFR by EGFR small-interfering RNAs in the SKBR3/EGFR (clone 5) reversed trastuzumab resistance. However, the SKBR3/EGFR (clone 5) cell line remained sensitive to lapatinib, an EGFR/HER2 inhibitor. Biochemical analysis using co-immunoprecipitation and proximity-based quantitative VeraTag assays demonstrated that high levels of EGFR phosphorylation, EGFR/EGFR homo-dimerization, and EGFR/HER2 hetero-dimerization were present in the trastuzumab-resistant cells. We conclude that EGFR over-expression can mediate trastuzumab resistance in both ER positive and ER negative cells and hypothesize that a threshold level of EGFR, in the absence of autocrine ligand production, is required to induce the resistant phenotype.

Polatuzumab Vedotin in Relapsed or Refractory Diffuse Large B-Cell Lymphoma.

PURPOSE: Patients with transplantation-ineligible relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) fare poorly, with limited treatment options. The antibody-drug conjugate polatuzumab vedotin targets CD79b, a B-cell receptor component. METHODS: Safety and efficacy of polatuzumab vedotin with bendamustine and obinutuzumab (pola-BG) was evaluated in a single-arm cohort. Polatuzumab vedotin combined with bendamustine and rituximab (pola-BR) was compared with bendamustine and rituximab (BR) in a randomly assigned cohort of patients with transplantation-ineligible R/R DLBCL (primary end point: independent review committee [IRC] assessed complete response [CR] rate at the end of treatment). Duration of response, progression-free survival (PFS), and overall survival (OS) were analyzed using Kaplan-Meier and Cox regression methods. RESULTS: Pola-BG and pola-BR had a tolerable safety profile. The phase Ib/II pola-BG cohort (n = 27) had a CR rate of 29.6% and a median OS of 10.8 months (median follow-up, 27.0 months). In the randomly assigned cohort (n = 80; 40 per arm), pola-BR patients had a significantly higher IRC-assessed CR rate (40.0% v 17.5%; P = .026) and longer IRC-assessed PFS (median, 9.5 v 3.7 months; hazard ratio [HR], 0.36, 95% CI, 0.21 to 0.63; P < .001) and OS (median, 12.4 v 4.7 months; HR, 0.42; 95% CI, 0.24 to 0.75; P = .002; median follow-up, 22.3 months). Pola-BR patients had higher rates of grade 3-4 neutropenia (46.2% v 33.3%), anemia (28.2% v 17.9%), and thrombocytopenia (41% v 23.1%), but similar grade 3-4 infections (23.1% v 20.5%), versus the BR group. Peripheral neuropathy associated with polatuzumab vedotin (43.6% of patients) was grade 1-2 and resolved in most patients. CONCLUSION: Polatuzumab vedotin combined with BR resulted in a significantly higher CR rate and reduced the risk of death by 58% compared with BR in patients with transplantation-ineligible R/R DLBCL.

A Clinically Applicable Gene-Expression Classifier Reveals Intrinsic and Extrinsic Contributions to Consensus Molecular Subtypes in Primary and Metastatic Colon Cancer.

PURPOSE: Four consensus molecular subtypes (CMS1-4) of colorectal cancer were identified in primary tumors and found to be associated with distinctive biological features and clinical outcomes. Given that distant metastasis largely accounts for colorectal cancer-related mortality, we examined the molecular and clinical attributes of CMS in metastatic colorectal cancer (mCRC). EXPERIMENTAL DESIGN: We developed a colorectal cancer-focused NanoString-based CMS classifier that is ideally suited to interrogate archival tissues. We successfully used this panel in the CMS classification of formalin-fixed paraffin-embedded (FFPE) tissues from mCRC cohorts, one of which is composed of paired primary tumors and metastases. Finally, we developed novel mouse implantation models to enable modeling of colorectal cancer in vivo at relevant sites. RESULTS: Using our classifier, we find that the biological hallmarks of mCRC, including CMS, are in general highly similar to those observed in nonmetastatic early-stage disease. Importantly, our data demonstrate that CMS1 has the worst outcome in relapsed disease, compared with other CMS. Assigning CMS to primary tumors and their matched metastases reveals mostly concordant subtypes between primary and metastasis. Molecular analysis of matched discordant pairs reveals differences in stromal composition at each site. The development of two novel in vivo orthotopic implantation models further reinforces the notion that extrinsic factors may impact on CMS identification in matched primary and metastatic colorectal cancer. CONCLUSIONS: We describe the utility of a NanoString panel for CMS classification of FFPE clinical samples. Our work reveals the impact of intrinsic and extrinsic factors on colorectal cancer heterogeneity during disease progression.

Correction: First-in-human phase 1 study of the BTK inhibitor GDC-0853 in relapsed or refractory B-cell NHL and CLL.

[This corrects the article DOI: 10.18632/oncotarget.24310.].

Polatuzumab vedotin or pinatuzumab vedotin plus rituximab in patients with relapsed or refractory non-Hodgkin lymphoma: final results from a phase 2 randomised study (ROMULUS).

BACKGROUND: Antibody-drug conjugates (ADCs) polatuzumab vedotin (pola) and pinatuzumab vedotin (pina) showed clinical activity and tolerability in phase 1 trials. The aim of this multicentre, open-label, phase 2 study was to compare rituximab plus pola (R-pola) or pina (R-pina) in patients with relapsed or refractory diffuse large B-cell lymphoma and follicular lymphoma. METHODS: In this phase 2 randomised study at 39 investigational sites in six countries, patients were randomly assigned (1:1), by use of a dynamic hierarchical randomisation scheme, to receive R-pola or R-pina (375 mg/m2 rituximab plus 2·4 mg/kg ADCs) every 21 days until disease progression or unacceptable toxicity up to 1 year. Treatment allocations were not masked to the investigator, patients or sponsor after the patients were enrolled and randomly assigned. The primary objectives were safety and tolerability, and antitumour response. The study is registered with ClinicalTrials.gov, number NCT01691898, and is closed to accrual. FINDINGS: 81 patients with diffuse large B-cell lymphoma and 42 with follicular lymphoma were recruited between Sept 27, 2012, and Oct 10, 2013, and were assigned to treatment. 81 patients with diffuse large B-cell lymphoma and 41 patients with follicular lymphoma were eligible for analysis. Of the 42 patients with diffuse large B-cell lymphoma who received R-pina, 25 (60%, 95% CI 43-74) achieved an objective response and 11 (26%, 95% CI 14-42) achieved a complete response. Of the 39 patients in this cohort who received R-pola, 21 (54%, 95% CI 37-70) achieved an objective response, and eight (21%, 95% CI 9-36) achieved a complete response. Of the 21 patients in the follicular lymphoma cohort who received R-pina, 13 (62%, 95% CI 38-82) achieved an objective response, and one (5%, 95% CI 0·1-24) achieved a complete response. Of the 20 patients in this cohort who received R-pola, 14 (70%, 95% CI 46-88) achieved an objective response, and nine (45%, 95% CI 23-68) achieved a complete response. In the diffuse large B-cell lymphoma cohort, grade 3-5 adverse events occurred in 33 (79%) of 42 patients receiving R-pina (most common were neutropenia [29%] and hyperglycaemia [10%]; nine [21%] grade 5 adverse events, five of which were infection-related), and in 30 (77%) of 39 patients receiving R-pola (most common were neutropenia [23%], anaemia [8%] and diarrhoea [8%]; no grade 5 adverse events). In the follicular lymphoma cohort, grade 3-5 adverse events occurred in 13 (62%) of 21 patients receiving R-pina (most common were neutropenia [29%] and hyperglycaemia [14%]; no grade 5 adverse events) and in ten (50%) of 20 patients receiving R-pola (most common were neutropenia [15%] and diarrhoea [10%]; one grade 5 adverse event). INTERPRETATION: R-pina and R-pola are potential treatment options in patients with relapsed or refractory diffuse large B-cell lymphoma and follicular lymphoma. Pola was selected by the study funder for further development in non-Hodgkin lymphoma, partly because of longer durations of response than pina, and an overall benefit-risk favouring R-pola. FUNDING: F Hoffmann-La Roche.

Elevated Levels of BRAFV600 Mutant Circulating Tumor DNA and Circulating Hepatocyte Growth Factor Are Associated With Poor Prognosis in Patients With Metastatic Melanoma.

PURPOSE: We performed a retrospective exploratory analysis to evaluate the prognostic and predictive effect of two circulating biomarkers, BRAFV600 mutant circulating tumor DNA (ctDNA) and circulating hepatocyte growth factor (cHGF), in metastatic melanoma. MATERIALS AND METHODS: This study evaluated patients from BRIM-3, a phase III trial comparing vemurafenib and dacarbazine in 675 patients with BRAFV600 mutated advanced melanoma. ctDNA was measured using droplet digital polymerase chain reaction, and cHGF was measured by enzyme-linked immunosorbent assay. Overall survival (OS) was estimated using the Kaplan-Meier method, and hazard ratios (HRs) were estimated using Cox proportional hazards modeling. Partitioning analysis was used to group patients into risk categories. RESULTS: Patients with elevated levels of baseline BRAFV600 ctDNA had significantly shorter median OS than those with undetectable levels of ctDNA (vemurafenib arm, 9.9 v 21.4 months, respectively, and dacarbazine arm: 6.1 v 21.0 months, respectively). Median OS was also shorter in patients with high levels of cHGF compared with those with low cHGF (vemurafenib arm, 11.9 v 17.3 months, respectively, and dacarbazine arm, 6.1 v 14.4 months, respectively). In a multivariable proportional hazards model with adjustment for lactate dehydrogenase, Eastern Cooperative Oncology Group status, disease stage, and treatment, ctDNA and cHGF were both independent prognostic factors for OS, (HR, 1.75; 95% CI, 1.35 to 2.28 for high v undetectable ctDNA; HR, 1.24; 95% CI, 1.00 to 1.53 for high v low cHGF). Using partitioning analysis, we found that patients with elevated ctDNA combined with elevated cHGF constituted the highest risk group with significantly shorter OS. CONCLUSION: Here, we report that BRIM-3 patients with high levels of ctDNA and cHGF have worse OS regardless of treatment and that these factors are independent prognostic markers for metastatic melanoma.