Verastem (United States)

Abstract Despite promising results from recent FDA-approved therapies, many patients with advanced melanoma develop resistance to both immunotherapy and targeted therapy. A common resistance mechanism to targeted therapy is upregulation of the PI3K/AKT signaling pathway, which has also been shown to promote the development of melanoma brain metastases. Historically, AKT inhibitors have failed in the clinic due to their limited efficacy or intolerable toxicity. Proteomic analysis comparing non-metastatic vs brain metastatic primary tumors in mice revealed focal adhesion kinase (FAK) as an AKT1 specific effector and a potential alternative therapeutic target. FAK is a non-receptor tyrosine kinase that localizes primarily to focal adhesions to regulate cell migration. To determine whether targeting FAK alone or in combination with the RAF/MEK inhibitor avutometinib reduces brain metastases and prolongs survival, we utilized both autochthonous and syngeneic melanoma mouse models. Mice with either subcutaneous tumors or established brain metastases were treated with FAK inhibitor, RAF/MEK inhibitor, or the combination of FAK and RAF/MEK inhibitors. Each cohort was assessed for tumor onset, growth, metastasis, and survival. Our results show that combined RAF/MEK/FAK inhibition significantly delays tumor onset, causes regression of established tumors, prevents the development of brain metastases, promotes the regression of established brain metastases, and prolongs survival. Based on these results, we have initiated a clinical trial evaluating the efficacy of the RAF/MEK inhibitor avutometinib in combination with the FAK inhibitor defactinib in patients with brain metastases from cutaneous melanoma. Additionally, we are assessing whether RAF, MEK, and FAK inhibition can be combined with standard of care immunotherapy and brain-targeted radiotherapy to create more durable responses that further improve survival in this disease.

Low-grade-serous ovarian carcinomas (LGSOC) are rare tumors characterized by a high recurrence rate and limited treatment options. Most LGSOC are estrogen receptor (ER)-positive and demonstrate alterations in the RAS/MAPK pathway. Avutometinib is a dual RAF/MEK clamp, whereas defactinib and VS-4718 are focal adhesion kinase (FAK) inhibitors. Fulvestrant is an ER antagonist/degrader. We assessed the preclinical efficacy of fulvestrant, avutometinib + VS-4718 (FAKi), and the triple combination in a chemotherapy/aromatase inhibitor-resistant LGSOC patient-derived tumor xenograft (PDX) model. Tissue obtained from a LGSOC patient wild-type for KRAS/NRAS/BRAF mutations in progression after chemotherapy/anastrozole was transplanted into female CB17/lcrHsd-Prkdc/SCID mice (PDX-OVA(K)250). The animals were treated with either saline/control, fulvestrant, avutometinib/FAKi, or the triple combination of avutometinib/FAKi/fulvestrant. Avutometinib and FAKi were given five-days on and two-days off through oral gavage. Fulvestrant was administered subcutaneously weekly. Mechanistic studies were performed ex vivo using Western blot assays. Animals treated with the triple combination demonstrated stronger tumor growth inhibition compared to all the other experimental groups including control/saline (p < 0.001), single-agent fulvestrant (p = 0.04 from day eight and onwards), and avutometinib/FAKi (p = 0.02 from day 18). Median survival for mice treated with saline/control was 29 days while mice in all other experimental groups were alive at day 60 (p < 0.0001). Treatment was well tolerated across all experimental treatments. By Western blot, exposure of OVA(K)250 to the triple combination demonstrated a decrease in phosphorylated MEK (p-MEK) and p-ERK levels. The addition of fulvestrant to avutometinib/FAKi is well tolerated in vivo and enhances the antitumor activity of avutometinib/FAKi in a LGSOC-PDX model with acquired resistance to chemotherapy/aromatase inhibitors. These results support the clinical evaluation of avutometinib/defactinib in combination with fulvestrant or an aromatase inhibitor in patients with recurrent LGSOC.

e16403 Background: Activating KRAS mutations in pancreatic ductal carcinomas (PDAC) occur in &gt; 90% of patients (pts). Avutometinib (A) is a RAF/MEK clamp that potently inhibits MEK kinase while blocking compensatory reactivation of MEK. Defactinib (D) is a selective inhibitor of FAK, a target shown to mediate resistance. RAMP 205 (NCT05669482) is a Phase 1b/2 study assessing A/D + gemcitabine/nab-paclitaxel (GnP) in first-line metastatic PDAC. Preliminary data suggest synergistic activity with this combination. Updated data on additional dosing cohorts are presented here. Methods: Eligible pts had histologically confirmed newly diagnosed metastatic PDAC and measurable disease, ECOG PS ≤1, adequate organ function, and no prior treatment for metastatic disease. Pts were treated in 3+3 cohorts with escalating oral doses of A and D in combination with IV doses of GnP on a 4-week schedule (Table). Results: At data cutoff (03Jan2025), 54 pts were enrolled and included in the safety analysis: 46% men, median age 59 years (range, 36-79), and 42.5% (23/54) ECOG PS of 1. Pts were enrolled in the following dose levels: DL1 (n = 12), DL0 (n = 6), DL-1 (n = 12), DL1a (n = 12), and DL2a (n = 12). The MTD has not been reached. There was one DLT: grade 3 febrile neutropenia in DL1, that resolved within 3 days. The most common treatment-related adverse events (all grades, all dose groups) were fatigue (63%), nausea (46%), neutropenia (46%), alopecia (41%), diarrhea (39%), anemia (30%), maculo-papular rash (30%), peripheral edema (28%), hyperbilirubinemia (24%), vomiting (24%), dermatitis acneiform (22%), thrombocytopenia (22%), and blurred vision (22%). The most common grade ≥3 treatment-related adverse events were neutropenia (39%), anemia (20%), fatigue (7%), and increased ALT (7%). Thirty-nine efficacy evaluable pts were enrolled at least 6 months prior to data cutoff. Objective Response Rate (ORR) and Disease Control Rate (DCR) for ≥4 cycles are listed in the Table. Conclusions: A/D + GnP have been combined in 5 dose cohorts. The MTD has not been reached. Enrollment and evaluation of mature data are ongoing to identify the recommended phase 2 dose. Clinical trial information: NCT05669482 . RAMP 205 dose levels and efficacy for patients enrolled ≥6 months prior to data cutoff. Dose Level A(mg) BIW* D(mg) BID* Gemcitabine (mg/m 2 ) Nab-Paclitaxel (mg/m 2 ) Days Chemo Dosing ORR% (n/N) DCR≥4 cycles% (n/N) 1 2.4 200 800 125 1,8,15 83% (5/6) 83% (5/6) 0 3.2 200 800 100 1,8,15 100% (1/1) 100% (1/1) -1 ^ 2.4 200 800 100 1,8,15 27% (3/11) † 82% (9/11) 1a # 3.2 200 800 125 1,15 33% (3/9) ◊ 56% (5/9) 2a 3.2 200 1000 125 1,15 25% (3/12) 58% (7/12) *Dosing 3 / 4 weeks. ^ 1 pt excluded from efficacy analysis due to no post baseline scan. # 3 pts excluded from efficacy analysis: 1 due to no post baseline scan and 2 due to incorrect histology per eligibility criteria. † Includes 2 unconfirmed responses. ◊Includes 1 unconfirmed response.

Abstract Although there are targeted therapies currently approved for cancers with KRAS G12C and BRAF V600E (class I) mutations, there is still significant unmet medical need for patients harboring NRAS or BRAF class II/III alterations which are found in a range of cancers including melanoma and lung cancer. Avutometinib is a first-in-class orally available RAF/MEK clamp that potently inhibits MEK1/2 kinase activities and induces formation of dominant negative RAF/MEK complexes thereby blocking compensatory activation of MEK by RAF. The combination of avutometinib with the focal adhesion kinase (FAK) inhibitor defactinib has shown clinical activity for patients with low-grade serous ovarian cancer and is currently being investigated in a Phase 3 confirmatory study (RAMP 301; NCT06072781). Here, we tested the combination of avutometinib with a pan-RAF inhibitor (pan-RAFi) in cancer models harboring NRAS or BRAF class III mutations. In 3D proliferation assays, avutometinib inhibited cell proliferation across multiple MAPK pathway alterations including NRAS, and BRAF class II and III. Combination strategies of avutometinib with inhibitors of upstream MAPK pathway signaling, including pan-HER, SOS1 and pan-RAF inhibitors, were explored and striking synergy was observed between avutometinib and pan-RAF inhibitors in reducing viability of tumor cells in vitro. In a BRAF class III non-small cell lung cancer patient-derived xenograft (PDX) model (LU3057), the combination of avutometinib with the pan-RAFi exarafenib induced strong tumor regressions in all the mice, whereas avutometinib alone induced tumor stasis. In an NRAS mutant melanoma PDX model (ME9518), the combination of avutometinib and exarafenib showed deep tumor regression, whereas avutometinib or exarafenib single agents did not induce tumor regression. In contrast to the tumor regressions induced by avutometinib plus exarafenib in this ME9518 model, the combination of the MEK-only inhibitor binimetinib with exarafenib caused substantial body weight loss and failed to show tumor regression. Strong tumor regressions in all mice were also observed with the combination of avutometinib and the pan-RAFi belvarafenib in an NRAS mutant xenograft model (SKMEL2). Mechanistically, the deep tumor regressions observed with the combination of avutometinib plus exarafenib corresponded with virtually complete elimination of MAPK pathway markers such as pMEK, DUSP4 and pS6 in the tumors relative to avutometinib or exarafenib alone which conferred less complete inhibition. These results demonstrate that the combination of avutometinib with a pan-RAFi is especially efficacious and is well tolerated, indicating that clinical evaluation of avutometinib in combination with a pan-RAF inhibitor for treatment of patients with NRAS or BRAF class III mutations may be warranted. Citation Format: Silvia Coma, Poulikos I. Poulikakos, Jonathan A. Pachter. RAF/MEK clamp avutometinib combined with a pan-RAF inhibitor induces nearly complete MAPK pathway inhibition with deep tumor regressions in NRAS or BRAF class III mutant models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4393.

The Rac1 P29S hotspot mutation in cutaneous melanoma is associated with resistance to MAPK pathway inhibitors (MAPKi) and worse clinical outcomes. Moreover, activation of Rac1 guanine exchange factors (GEFs) also promotes MAPKi-resistance, particularly in undifferentiated melanoma cells. Here we delineate mechanisms of Rac1-driven MAPKi-resistance and identify strategies to inhibit the growth of this class of cutaneous melanomas. We find that Rac1-driven melanomas manifest pleiotropic resistance mechanisms including (i) reduced dependence on BRAF/MEK, (ii) activation of alternative MAPK pathways utilizing Jun kinase and p38 MAP kinase, and (iii) a partial reliance on YAP/TAZ signaling. Importantly, although Rac1-driven melanoma cells display reduced dependence on BRAF/MEK, they are not completely ERK-independent. Additionally, the presence of activated Rac1 appears to create a dependency on focal adhesion kinase (FAK) signaling in undifferentiated melanoma cells. Therefore, despite the pleiotropic mechanisms of Rac1-driven MAPKi resistance, we find that combined inhibition of RAF and MEK with the RAF/MEK clamp avutometinib and FAK with the FAK inhibitor defactinib is a promising approach for suppressing the growth of Rac1-driven melanoma cells. Thus, the avutometinib plus defactinib combination, which is currently being investigated for brain metastatic cutaneous melanoma may also have utility against Rac1-driven MAPKi-resistance in heavily pre-treated, advanced disease.

The Rac1 P29S hotspot mutation in cutaneous melanoma is associated with resistance to MAPK pathway inhibitors (MAPKi) and worse clinical outcomes. Moreover, activation of Rac1 guanine exchange factors (GEFs) also promotes MAPKi-resistance, particularly in undifferentiated melanoma cells. Here we delineate mechanisms of Rac1-driven MAPKi-resistance and identify strategies to inhibit the growth of this class of cutaneous melanomas. We find that Rac1-driven melanomas manifest pleiotropic resistance mechanisms including (i) reduced dependence on BRAF/MEK, (ii) activation of alternative MAPK pathways utilizing Jun kinase and p38 MAP kinase, and (iii) a partial reliance on YAP/TAZ signaling. Importantly, although Rac1-driven melanoma cells display reduced dependence on BRAF/MEK, they are not completely ERK-independent. Additionally, the presence of activated Rac1 appears to create a dependency on focal adhesion kinase (FAK) signaling in undifferentiated melanoma cells. Therefore, despite the pleiotropic mechanisms of Rac1-driven MAPKi resistance, we find that combined inhibition of RAF and MEK with the RAF/MEK clamp auvotometinib and FAK with the FAK inhibitor defactinib is a promising approach for suppressing the growth of Rac1-driven melanoma cells. Thus, the avutometinib plus defactinib combination, which is currently being investigated for brain metastatic cutaneous melanoma may also have utility against Rac1-driven MAPKi-resistance in heavily pre-treated, advanced disease.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy that is often resistant to therapy. An immune suppressive tumor microenvironment (TME) and oncogenic mutations in KRAS have both been implicated as drivers of resistance to therapy. Mitogen-activated protein kinase (MAPK) inhibition has not yet shown clinical efficacy, likely because of rapid acquisition of tumor-intrinsic resistance. However, the unique PDAC TME may also be a driver of resistance. We found that long-term focal adhesion kinase (FAK) inhibitor treatment led to hyperactivation of the RAS/MAPK pathway in PDAC cells in mouse models and tissues from patients with PDAC. Concomitant inhibition of both FAK (with VS-4718) and rapidly accelerated fibrosarcoma and MAPK kinase (RAF-MEK) (with avutometinib) induced tumor growth inhibition and increased survival across multiple PDAC mouse models. In the TME, cancer-associated fibroblasts (CAFs) impaired the down-regulation of MYC by RAF-MEK inhibition in PDAC cells, resulting in resistance. By contrast, FAK inhibition reprogramed CAFs to suppress the production of FGF1, which can drive resistance to RAF-MEK inhibition. The addition of chemotherapy to combined FAK and RAF-MEK inhibition led to tumor regression, a decrease in liver metastasis, and improved survival in KRAS-driven PDAC mouse models. Combination of FAK and RAF-MEK inhibition alone improved antitumor immunity and priming of T cell responses in response to chemotherapy. These findings provided the rationale for an ongoing clinical trial evaluating the efficacy of avutometinib and defactinib in combination with gemcitabine and nab-paclitaxel in patients with PDAC and may suggest further paths for combined stromal and tumor-targeting therapies.

IntroductionLow grade serous ovarian cancer (LGSOC) is a rare, clinically distinct cancer commonly driven by RAS/MAPK pathway alterations. Avutometinib ([A] oral RAF/MEK clamp) + defactinib ([D] oral FAK inhibitor) is being investigated in recurrent LGSOC. We report the primary analysis of A±D from RAMP 201.MethodsPatients with recurrent, measurable LGSOC after at least one line of platinum chemotherapy were enrolled. Patients were randomized to A (4.0mg BIW) monotherapy or A (3.2mg BIW) + D (200mg BID). A+D was selected for expansion. Subsequently a 1.6mg dose of A +D was evaluated. The primary endpoint is ORR per RECISTv1.1 by BICR.ResultsAt the 30June2024 visit cutoff, 115 patients were enrolled to A (3.2mg BIW) + D (200mg BID). Median age was 54 (range, 21-87) and patients had a median of 3 (range, 1-9) prior lines of therapy. Prior therapies included endocrine (86%), bevacizumab (51%), and MEK inhibitor (22%). Confirmed ORR of 31% was observed (44% KRAS mt; 17% KRAS wt); median DOR, 31.1mo and median PFS, 12.9mo. The most common non-laboratory treatment-related AEs (all grades, grade ≥3) were nausea (67.0%, 2.6%) and diarrhea (58.3%, 7.8%). The most common laboratory abnormality was increased blood creatinine phosphokinase (60.0%, 24.3%). Discontinuations due to AEs were infrequent (10%). Results from all cohorts will be presented.Conclusion/ImplicationsA+D was well tolerated allowing prolonged exposure to therapy. ORR and durable responses observed are clinically meaningful in this heavily pretreated population and support the potential of A+D as a new standard of care for recurrent LGSOC. LB007/#1548 Table 1

Abstract Despite promising results from recent FDA-approved therapies, many advanced melanoma patients develop resistance to both immunotherapy and targeted therapy. A common resistance mechanism to targeted therapy is upregulation of the PI3K/AKT signaling pathway, which has also been shown to promote the development of melanoma brain metastases. Historically, AKT inhibitors have failed in the clinic due to their limited efficacy or intolerable toxicity. Proteomic analysis comparing non-metastatic vs brain metastatic primary tumors in mice revealed focal adhesion kinase (FAK) as an AKT1 specific effector and a potential alternative therapeutic target. FAK is a non-receptor tyrosine kinase that localizes primarily to focal adhesions to regulate cell migration. To determine whether targeting FAK alone or in combination with the RAF/MEK inhibitor avutometinib reduces brain metastases and prolongs survival, we utilized both autochthonous and syngeneic melanoma mouse models. Mice with either subcutaneous tumors or established brain metastases were treated with FAK inhibitor, RAF/MEK inhibitor, or the combination of FAK and RAF/MEK inhibitors. Each cohort was assessed for tumor onset, growth, metastasis, and survival. Our results show that combined RAF/MEK/FAK inhibition significantly delays tumor onset, causes regression of established tumors, prevents the development of brain metastases, promotes the regression of established brain metastases, and prolongs survival. In addition, patient-derived BRAF V600E melanoma xenograft mouse models resistant to the BRAF inhibitor dabrafenib and the MEK inhibitor trametinib, were sensitive to combined RAF/MEK/FAK blockade. The addition of the BRAF inhibitor encorafenib to these models further enhanced the effect on tumor growth. These results support the initiation of a clinical trial evaluating the efficacy of the RAF/MEK inhibitor avutometinib in combination with the FAK inhibitor defactinib in patients with brain metastases from cutaneous melanoma. Additionally, we are assessing non-canonical roles of FAK in modulating the tumor microenvironment to determine whether avutometinib and defactinib also enhance the efficacy of immune checkpoint inhibition in this disease. Citation Format: Karly A. Stanley, Jared D. Almazan, Tursun Turapov, David A. Kircher, Gennie L. Parkman, MiKaela N. Field, Katie M. Culver, Christopher M. Stehn, Silvia Coma, Jonathan A. Pachter, Howard Colman, Sheri L. Holmen. Combined inhibition of RAF, MEK, and FAK attenuates melanoma brain metastases and prolongs survival in preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4127.

Abstract KRAS mutations (mt) occur in up to 98% of pancreatic ductal adenocarcinoma (PDAC) and represent a key initiating event in PDAC carcinogenesis. Therapeutic efforts targeting the RAS/RAF/MEK/ERK (MAPK) pathway with MEK-only inhibitors have been unsuccessful in substantially modifying PDAC prognosis. Thus, novel strategies are needed to overcome putative mechanisms of resistance to MEK inhibition such as focal adhesion kinase (FAK) pathway activation. Another hallmark of PDAC is its high stromal density, which is thought to limit the penetration of cytotoxic drugs and T cells into the tumor and has been shown to be correlated with FAK hyperactivation, altogether supporting co-targeting the MAPK and FAK pathways to achieve deep and durable responses for patients with PDAC. Avutometinib is a RAF/MEK clamp that potently inhibits MEK kinase activity and induces dominant negative RAF-MEK complexes preventing phosphorylation of MEK by ARAF, BRAF and CRAF. This unique mechanism allows avutometinib to block MEK signaling without the compensatory re-activation of MEK that appears to limit the efficacy of MEK-only inhibitors. Preclinically, avutometinib has shown strong anti-proliferative potency across tumor cell lines carrying KRAS mt including PDAC cell lines. Clinically, avutometinib in combination with the FAK inhibitor (FAKi) defactinib received breakthrough therapy designation for the treatment of patients with recurrent low-grade serous ovarian cancer. Here, we tested the combination of avutometinib and FAK inhibition with standard of care chemotherapy in PDAC mouse models. In a KRAS/p53 pancreatic cancer mouse model, we found that whereas the combination of avutometinib + FAKi induced tumor inhibition and increased survival, addition of chemotherapy (gemcitabine + paclitaxel as a surrogate for nab-paclitaxel) to avutometinib/FAKi induced tumor regression. These results support the ongoing clinical study of avutometinib and defactinib in combination with standard of care chemotherapy (gemcitabine/nab-paclitaxel) for patients with front-line metastatic PDAC (NCT05669482). Other combinations being explored preclinically include avutometinib with G12D inhibition (G12Di) in KRAS G12D PDAC, which accounts for 28% of patients with PDAC. In 3D culture, avutometinib was synergistic with the G12Di MRTX1133 in reducing viability of a panel of KRAS G12D PDAC cell lines. In mouse models, avutometinib enhanced anti-tumor efficacy of MRTX1133 in a KRAS G12D pancreatic cancer patient-derived xenograft model. Furthermore, in KRAS mt PDAC cell lines, avutometinib was synergistic with the autophagy inhibitors chloroquine or apilimod. Indeed, dual treatment with avutometinib + MRTX1333 synergistically decreased proliferation and increased autophagic flux in KRAS G12D PDAC cell lines, supporting testing the triple combination of avutometinib + G12Di + autophagy inhibitor in patients with KRAS G12D pancreatic cancers. In conclusion, we show that avutometinib is a unique RAF/MEK clamp with the potential to become the backbone of therapy for pancreatic cancers. Citation Format: Silvia Coma, Xiuting Liu, Noah L. Pieper, Wen-Hsuan Chang, Kirsten L. Bryant, Channing J. Der, David G. DeNardo, Jonathan A. Pachter. The RAF/MEK clamp avutometinib as the backbone of therapy for pancreatic cancer: Novel combinations with standard of care chemotherapy, FAK inhibitors, KRAS G12D inhibitors and/or autophagy inhibitors [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A091.