NRG1 fusion-driven cancers: A systematic literature review and meta-analysis

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Background: Neuregulin 1 (NRG1) fusion proteins have recently been identified as oncogenic drivers in diverse cancers with high unmet medical need. We recently reported promising responses in patients with cancers harboring NRG1 fusions treated with the bispecific antibody MCLA-128 (Schram 2019). The objective of this study was for the first time to quantitatively summarize the frequency of tumors harboring NRG1 fusions reported in the published literature. Methods: Neuregulin 1 (NRG1) fusion proteins have recently been identified as oncogenic drivers in diverse cancers with high unmet medical need. We recently reported promising responses in patients with cancers harboring NRG1 fusions treated with the bispecific antibody MCLA-128 (Schram 2019). The objective of this study was for the first time to quantitatively summarize the frequency of tumors harboring NRG1 fusions reported in the published literature. Results: Out of 212 articles identified in the literature as of 31-Jul-2019, 37 met the inclusion criteria and were abstracted. 13 different tumor types were identified as harboring NRG1 fusions including 5 tumor (sub)types which met the criteria for frequency meta-analysis (Table 1). NRG1 fusions were most frequent in pancreatic adenocarcinoma (3.3%, 95% confidence intervals (CI): 0.3-28.7%; apparent enrichment in KRAS WT) and NSCLC (0.8% 95% CI: 0.3-2.7%) with an enrichment in invasive mucinous adenocarcinoma (9.8%, 95% CI: 4.7-19.6%). Statistically significant heterogeneity was observed indicating substantial variation across studies in each analysis. For tumor types that did not meet the criteria for meta-analysis (uterine, renal cell, ovarian, colorectal, head and neck, bladder, prostate and sarcoma) the reported frequency of NRG1 fusions was typically less than 1%. Conclusions: NRG1 fusions are present across a wide range of different solid tumor types, most frequently in NSCLC and PDAC. NRG1 fusion-driven cancers represent a potential tumor-agnostic therapeutic target. The advent of new treatment options and increased genomic testing will allow a more precise estimation of the frequency of NRG1 fusions in cancer. [Table: see text]

Clinical activity of MCLA-128 (zenocutuzumab) in combination with endocrine therapy (ET) in ER+/HER2-low, non-amplified metastatic breast cancer (MBC) patients (pts) with ET-resistant disease who had progressed on a CDK4/6 inhibitor (CDK4/6i)

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Background: MCLA-128 (zenocutuzumab) is an ADCC-enhanced humanized bispecific antibody targeting HER2 and HER3 and potently blocking HER3-ligand induced receptor dimerization. Upregulation of Her2:Her 3 pathway is a means of resistance to ET in HR+ breast cancer, indicating a potential role for MCLA-128. In preclinical studies, the combination of MCLA-128 with ET in breast cancer xenografts outperformed single drug treatments. The current study explores the use of MCLA-128 to rescue pts with ET-resistant MBC who have progressed on a CDK4/6i. Methods: This phase II, open-label trial planned for up to 40 evaluable women with HR+, HER2 low (IHC 1+/IHC 2+ with negative FISH) MBC, who had progressed on a CDK4/6i and up to 3 lines of ET, who had received ≤ 2 chemotherapy regimens in the metastatic setting. Pts received MCLA-128 (750 mg, 2h IV, flat dose) q3w combined with last ET on which the pt had previously progressed immediately prior to study entry. Disease control rate (DCR; RECIST 1.1, per investigator), best overall response (BOR), overall response rate (ORR), safety, and PK, are evaluated. Data cut off was 14Nov2019. Results: 48 pts were treated, all of whom had progressed on a CDK4/6i. Pts had received a median 2 prior ET lines (range 1-5) and 1 line (range 1-3) of chemotherapy. Pts had a median number of 3 metastatic sites (range 1-6) and 42 (88%) had visceral involvement. Among 42 pts evaluable for efficacy, DCR was 45% (90% CI 32-59) with 2 pts having unconfirmed PR and 19 pts SD as BOR. Common related AEs (all grades; G3-4) were asthenia/fatigue (27%; 2%), diarrhea (25%; 0), nausea (21%; 0). No clinically significant LVEF decline was seen. At the end of cycle 1, mean trough level of MCLA-128 was 15.5 µg/mL, and mean terminal half-live was 102 h (n = 19-21). Data on the primary endpoint, clinical benefit rate at 24 weeks, and biomarkers will be provided. Conclusions: The addition of MCLA-128 to the last line of ET showed clinical activity after ET+CDK4/6i failure and a favorable safety profile. Clinical trial information: NCT03321981 .

Abstract PR02: Clinical proof of concept for MCLA-128, a bispecific HER2/3 antibody therapy, in NRG1 fusion-positive cancers

Background: NRG1 fusions are oncogenic drivers of various cancers including pancreatic and lung adenocarcinomas. NRG1 fusion proteins bind to HER3, leading to HER2/HER3 heterodimerization, increased downstream signaling, and tumor growth. MCLA-128 is a bispecific antibody directed against HER2 and HER3 that docks on HER2 and blocks ligand binding to HER3, thereby preventing downstream signaling. In contrast to tyrosine kinase inhibitors or anti-HER3 monoclonal antibodies, MCLA-128 was shown in vitro and in vivo to potently inhibit ligand-driven tumor growth at high NRG1 levels present in NRG1 fusion-positive cancers. MCLA-128 offers a novel therapeutic paradigm for NRG1 fusion-positive cancers. MCLA-128 has a very well tolerated safety profile with <5% of patients reporting grade 3-4 suspected related AEs, and a notable lack of cardiotoxicity and severe gastrointestinal or skin toxicity. Methods: Cell line/xenograft models with NRG1 fusions (MDA-MB-175, OV5383, OV10-0050) were treated with MCLA-128. Patients with cancers harboring NRG1 fusions were identified using prospective molecular profiling by DNA/RNA-based next-generation sequencing (NGS). Patients with NRG1 fusion-positive tumors were treated with MCLA-128 (750 mg intravenously, every 2 weeks) on FDA-approved single-patient protocols. Results: Treatment with MCLA-128 inhibited proliferation of NRG1-fusion positive cell lines in vitro and resulted in rapid tumor shrinkage in NRG1 fusion-positive xenograft models in vivo. NGS identified 29 patients with NRG1 fusions across 8 tumor types (pancreas, lung, breast, sarcoma, prostate, gallbladder, unknown primary, and DLBCL). Of these 29 patients, 3 with chemotherapy-resistant metastatic cancer were treated with MCLA-128 and experienced dramatic clinical and radiographic responses. A 52-year-old man with ATP1B1-NRG1 fusion-positive pancreatic ductal adenocarcinoma (PDAC) with liver metastases, worsening fatigue, and weight loss, achieved rapid clinical and pharmacodynamic responses (CA19-9 decrease from 262 to 56). Imaging at 8 weeks demonstrated a partial response (-44%) by RECIST v1.1 and a complete response by PERCIST. A 34-year-old man with ATP1B1-NRG1 fusion-positive PDAC and longstanding tumor-associated abdominal pain also achieved rapid resolution of his pain, and normalization of CA 19-9 (418 to 11) upon treatment with MCLA-128. Imaging at 6 weeks showed tumor reduction (-22%) and that the liver metastases were non-FDG avid. A third patient with CD74-NRG1 fusion-positive non-small cell lung cancer (NSCLC) metastatic to the brain was started on MCLA-128. Despite progression on 6 prior lines of systemic therapy including afatinib, he rapidly responded to MCLA-128 with scans showing a partial response (-33%) by RECIST v1.1 at 8 weeks and tumor shrinkage in the brain. All patients remain on therapy (6+ months into treatment for the PDAC patients, 2+ months for the NSCLC patient) with no substantial toxicity. Conclusions: MCLA-128 leads to clinical responses in patients with NRG1 fusion-positive cancers through inhibition of ligand-driven activation of the HER3 pathway. A global, multicenter phase 2 basket trial for NRG1 fusion-positive cancers is now accruing patients.

Citation Format: Alison M Schram, Eileen M O’Reilly, Romel Somwar, Ryma Benayed, Sara Shameem, Thrusha Chauhan, Jean Torrisi, Jim Ford, David Maussang, Ernesto Wasserman, Marc Ladanyi, David M Hyman, L. Andres Sirulnik, Alexander Drilon. Clinical proof of concept for MCLA-128, a bispecific HER2/3 antibody therapy, in NRG1 fusion-positive cancers [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr PR02. doi:10.1158/1535-7163.TARG-19-PR02

First-in-human phase 1/2 study of MCLA-128, a full length IgG1 bispecific antibody targeting HER2 and HER3: Final phase 1 data and preliminary activity in HER2+ metastatic breast cancer (MBC)

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Background: MCLA-128 is a novel IgG1 bispecific antibody with enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) activity targeting HER2 and HER3 receptors. We report final phase 1 single agent escalation data, and safety and preliminary activity at the recommended phase 2 dose (RP2D). Methods: In the phase 1 part, patients (pts) with advanced solid tumors received MCLA-128 every 3 weeks (q3w) IV over 1-2 hr from 40 to 900 mg. In the phase 2 part, pts with selected metastatic indications were treated at the RP2D. Antitumor activity was assessed as per RECIST 1.1. Clinical benefit rate (CBR) was defined as CR + PR + SD ≥12 weeks. Results: As of January 2017, 28 advanced solid tumor pts were treated in the escalation part. No dose limiting toxicities were seen. The RP2D was established as 750 mg q3w (flat dose, corticosteroid premedication) based on safety and PK data. Fifteen pts with HER2 amplified tumors were treated at the RP2D (8 MBC, 4 gastric, 2 ovarian, 1 colorectal). Median age was 52 years (range 33-71), ECOG PS 0/1: 3/12, all ≥2 metastatic sites. The safety profile at the RP2D confirmed dose escalation data; the most common AEs were infusion related reactions in 6 pts (40%; G1-2 in 5 pts, G4 in 1 pt), and G1-2 diarrhea, rash, fatigue in 2 pts each (13%). No congestive heart failure or significant LVEF decreases occurred. The 8 MBC pts had a median 5.5 prior lines of metastatic therapy (range 4-14), all had progressed on 3 prior Her2 inhibitor therapies and received a median of 4.5 MCLA-128 cycles (range 2-12); 1 had a confirmed PR, 5 had SD (including 2 sustained, 11 and 12 cycles). SD was also seen in 2 evaluable MBC pts treated at 480 mg in the phase 1 part (7 and 4 cycles). Overall, CBR in these 10 MBC pts was 70%. Evaluation of other indications is ongoing. Conclusions: MCLA-128 showed a well tolerated safety profile. Consistent antitumor activity was seen in heavily pretreated MBC patients progressing on HER2 therapies. Further exploration of MCLA-128 based combinations with chemotherapy or trastuzumab in less pretreated MBC patients progressing after ≥2 prior Her2 inhibitors including TDM-1 is planned. Clinical trial information: NCT02912949.

Identification of pSTAT5 gene signature in hematologic malignancy

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Background: The JAK/STAT pathway is an important signaling pathway downstream of multiple cytokine and growth factor receptors. Receptor-associated JAKs are activated following receptor-ligand binding. Activated JAKs phosphorylate STAT proteins, which then dimerize and translocate to the nucleus where they modulate the expression of target genes. Dysregulated JAK/STAT signaling has been implicated in the pathogenesis of multiple human malignancies. Activating mutations in JAK2 and the associated activation of STAT5 in myeloproliferative neoplasia is one example of the involvement of this pathway in human cancer. Additionally, overactivated JAK/STAT signaling has been suggested as a survival mechanism in several human cancers. Given the importance of JAK/STAT dysregulation in human diseases, it is important to identify patients with an overactivated JAK/STAT pathway for possible treatment with JAK inhibitors. Thus, we developed a gene signature assay to detect overactivated JAK/STAT5 signaling. Methods: The cancer cell line encyclopedia (CCLE) and associated gene-expression data were used to correlate the activation status of STAT5 with the induction of a set of STAT5 target genes. First, we used 27 tumor cell lines of hematologic lineage, with predetermined phosphorylated STAT5 (pSTAT5) status, to derive STAT5 activation gene signatures. Next, the putative gene signatures were validated against a different set of 13 hematologic tumor cell lines. Results: With this approach, a collection of 7 target genes were identified (PIM1, CISH, SOCS2, ID1, LCN2, EPOR, and EGR1) whose expression significantly correlated with pSTAT5 status in the 40 hematologic tumor cell lines (P < .0001), either together or in specific subsets of 4 and 6 genes (Table). Conclusions: These 4-, 6-, and 7-gene signatures can be used to stratify or select for a patient population with activated JAK/STAT5 signaling that could potentially benefit from treatments targeting the JAK/STAT5 signaling pathway. [Table: see text]

Reductions in JAK2V617F allele burden with ruxolitinib treatment in COMFORT-II, a phase III study comparing the safety and efficacy of ruxolitinib to best available therapy (BAT)

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Background: Ruxolitinib is a potent and selective JAK1/2 inhibitor approved for the treatment of myelofibrosis (MF) based on results of the phase 3 COMFORT studies. Ruxolitinib demonstrated rapid and durable reductions in splenomegaly and improved MF-related symptoms and quality of life of patients (pts) with MF. Since one measure of efficacy is molecular response, this analysis correlates changes in mutant allele burden (%V617F) with spleen size reduction in COMFORT-II. Methods: COMFORT-II is a randomized, open-label, phase 3 study comparing ruxolitinib 15 or 20 mg twice daily (BID) with BAT. The primary endpoint was a ≥ 35% reduction in spleen volume from baseline (BL) at week 48. Change in %V617F was measured by allele specific qPCR. Pts were stratified by reduction in %V617F (< 10%, 10-20%, > 20%) and results were correlated with achievement of the primary endpoint. Results: More pts in the ruxolitinib arm had ≥ 10% V617F reductions compared with BAT (41% vs 5%; P = .01; Table). The majority of reductions > 20% were gradual and progressive over the course of the study; 2 pts had rapid reductions from 48% to 1% and 45% to 9% over 48 weeks. In the ruxolitinib arm, significantly more pts with a > 20% V617F reduction achieved the primary endpoint compared with pts with a < 10% reduction (79% vs 30%; P = .004); in each group, gender did not affect spleen response. For pts with < 10% reductions (15 mg BID, n = 16; 20 mg BID, n = 24), the average total daily dose (TDD) was ruxolitinib 29.6 mg; pts with > 20% reductions (15 mg BID, n = 3; 20 mg BID, n = 11) had a TDD of 35.3 mg. Conclusions: Pts who received ruxolitinib had larger reductions in JAK2V617F allele burden compared with BAT. %V617F reductions were gradual over the course of the 48-week study; longer follow-up is needed to determine the extent of allele burden reduction. [Table: see text]

Health-related quality of life (HRQoL) and symptom burden in patients (Pts) with myelofibrosis (MF) in the COMFORT-II study

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Background: Ruxolitinib has demonstrated rapid and durable reductions in splenomegaly and improved disease-related symptoms and QoL in 2 phase 3 studies (COMFORT-I and -II) in pts with primary MF (PMF), post-polycythemia vera-MF (PPV-MF), or post-essential thrombocythemia-MF (PET-MF). The prevalence of individual symptoms among these pts has not been defined. We evaluated the baseline HRQoL and symptoms among pts enrolled in COMFORT-II. Methods: COMFORT-II is a randomized, open-label, multicenter, phase 3 study comparing ruxolitinib with best available therapy. HRQoL and symptoms were assessed at baseline using the European Organisation for the Research and Treatment of Cancer QoL Questionnaire–Core 30 (EORTC QLQ‑C30) and Functional Assessment of Cancer Therapy–Lymphoma (FACT‑Lym); this analysis summarizes these scores for all pts, regardless of assigned treatment. Results: In COMFORT-II (N = 219), 52% of pts were aged > 65 years and 57% were male. By IPSS criteria (Cervantes et al. 2009), 40% had intermediate-2 and 60% had high-risk MF. Mean (95% CI) EORTC global health status/QoL (53.7 [50.6-56.7]; median, 50.0) and FACT-General total scores (73.0 [70.8-75.2]) were comparable to those for pts of similar age with other cancers (Oliva et al. 2011: median global health status score of 50 for acute myeloid leukemia [AML]). The most frequent symptoms (reported as “quite a bit” or “very much”) were fatigue (54%), dyspnea (30%), insomnia (30%), pain (29%), night sweats (23%), and itching (21%), and there were differences in baseline symptoms across MF subtypes (Table). Conclusions: This analysis shows that pts with MF experience severe disease-related symptoms and have diminished HRQoL similar to pts with AML, but because pts with MF have a longer life expectancy (an average of 2.3 to 4 years for high and intermediate-2 risk pts, respectively), they may suffer with a reduced QoL for many years. [Table: see text]

Association of cytokine levels and reductions in spleen size in COMFORT-II, a phase III study comparing ruxolitinib to best available therapy (BAT)

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Background: Ruxolitinib is a potent and selective oral JAK1/2 inhibitor that has been approved for the treatment of myelofibrosis (MF). Ruxolitinib has demonstrated rapid and durable reductions in splenomegaly and improved disease-related symptoms and quality of life (QoL) in 2 phase 3 studies (COMFORT-I and –II) in patients (pts) with primary MF (PMF), post-polycythemia vera-MF (PPV-MF), or post-essential thrombocythemia-MF (PET-MF). This analysis evaluated associations between cytokine levels and spleen size reductions in the COMFORT-II study. Methods: COMFORT-II is a randomized (2:1), open-label, phase 3 study comparing the safety and efficacy of ruxolitinib with BAT. Spleen volume was measured by MRI every 12 weeks and spleen length by palpation at each study visit. Plasma samples were analyzed using Rules Based Medicines Human MAP v1.6; 89 cytokines were measured at BL and wks 4, 24, and 48. Simple linear regression was used to evaluate the correlation between BL or change from BL in cytokine levels with % change of spleen size. Results: In the ruxolitinib arm, association was found between changes in TNF-α and leptin levels and % spleen volume reduction at wk 24 (TNF-α: N = 93; correlation coefficient [R] = 0.43; false discovery rate adjusted P value [P] < .01; leptin: N = 96; R = -0.28; P = .09) and wk 48 (TNF-α: N = 86; R = 0.43; P < .01; leptin: N = 87; R = -0.34; P = .02) that was not observed with BAT and was independent of JAK2V617F status. For ruxolitinib-treated JAK2V617F+ pts, higher leptin levels at BL were associated with greater % spleen length reductions at wk 48 (N = 45; R = -0.44; P = .11). A clear trend was observed for increased leptin levels that preceded weight gain on ruxolitinib treatment. For ruxolitinib-treated JAK2V617F+ pts, decreased IL-8 at wk 4 was associated with % spleen volume reductions at wk 24 (N = 68; R = 0.28; P = .24) and wk 48 (N = 60; R = 0.38; P = .15). Conclusions: This analysis has shown statistically significant associations between changes in cytokine levels and spleen size reductions. Further analysis is in progress to determine associations between cytokine levels and QoL or symptoms and to confirm these observations in an independent data set.

A phase Ib, open-label, dose-finding study of ruxolitinib in patients (pts) with primary myelofibrosis (PMF), post-polycythemia vera-myelofibrosis (PPV-MF), or post-essential thrombocythemia-myelofibrosis (PET-MF) and baseline platelets (PLTs) 50 to <100 x 109/l

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Background: Ruxolitinib, a potent and selective oral JAK1/2 inhibitor, has demonstrated rapid and durable reductions in splenomegaly and improved MF-related symptoms and quality of life in 2 phase 3 studies in pts with PMF, PPV-MF, or PET-MF. There is considerable experience in pts who develop thrombocytopenia on study, and ruxolitinib is well-tolerated with dose adjustment. However, there is limited experience in pts with baseline thrombocytopenia as those with low PLTs (< 100 x 109/L) were excluded from the phase 3 protocols. EXPAND (Evaluating RuXolitinib in Patients with Low Baseline PlAtelet CouNts Diagnosed With Myelofibrosis) will evaluate the safety of ruxolitinib and establish the maximum safe starting dose (MSSD) in thrombocytopenic pts with MF. Methods: This is a phase 1b, open-label, dose-finding study (NCT01317875) in pts with PMF, PPV-MF, or PET-MF and baseline PLT 50-100 x 109/L. A Bayesian logistic regression model with escalation with overdose control will be used to guide dose-escalation decisions. The study consists of 2 phases: dose-escalation and safety-expansion. The starting dose is ruxolitinib 5 mg twice daily (BID) with a maximum of 15 mg BID. In the dose-escalation phase, cohorts will be: 5 mg BID, 5 mg am/10 mg pm, 10 mg BID, 10 mg am/15 mg pm, and 15 mg BID; only pts with PLT 75-100 x 109/L (1st stratum) will initially be enrolled. Once safety is established at the first 2 dose levels (5 mg BID; 5 mg am/10 mg pm), pts with PLT 50-75 x 109/L will be included (2nd stratum). Each dose level in the 2nd stratum will be open only if both that dose and the following one are deemed safe in the 1st stratum. In the safety-expansion phase, 20 pts (10 from each stratum) additional to those treated at the MSSD during dose escalation will be treated at the respective MSSD for their stratum. In cohort 1 (n = 4), 3 pts were evaluable as they completed > 28 days of treatment; 1/4 pts discontinued after 6 doses due to disease progression. No dose-limiting toxicities were observed. The second cohort (5 mg am/10 mg pm) has completed enrollment (n = 3) and is ongoing.

Lenalidomide in myelodysplastic syndromes: where do we go from here?

Myelodysplastic syndromes (MDS), or myelodysplasia, are a heterogeneous group of bone marrow disorders characterized by progressive cytopenias and a propensity to evolve into acute leukemia. The only curative strategy in the treatment of MDS is stem cell transplantation. The advent of hypomethylating agents and, more recently, lenalidomide has changed the paradigm so that supportive treatment for patients who are not candidates for transplantation now includes drugs that may alter the natural history of the disease. The remarkable results observed with lenalidomide in patients with del(5q) has promoted intense research into the pathobiology of MDS and new approaches to treatment; it is hoped that this success will be extended to all subtypes of patients with MDS.

Acute promyelocytic leukemia: current strategies for the treatment of newly diagnosed disease

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia that comprises about 10% of cases. It is characterized by the accumulation of granulocytic cells blocked at the promyelocytic stage of differentiation in the bone marrow and the peripheral blood, life-threatening coagulopathy, and a remarkable response to treatment with all-trans-retinoic acid (ATRA), arsenic trioxide, and anthracyclines. Current treatment strategies with ATRA and anthracycline-based chemotherapy has dramatically transformed APL into the most curable of all acute leukemias. Advances in supportive care together with the early recognition of treatment-related complications have also contributed significantly to increased cure rates. In this review we explore current treatment strategies in the management of newly diagnosed APL. We also highlight practical points that may serve as a guideline for the treating physician and address current controversies in the choice of treatment.