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| Ref Type | Journal Article | ||||||||||||
| PMID | (30867592) | ||||||||||||
| Authors | Diamond EL, Durham BH, Ulaner GA, Drill E, Buthorn J, Ki M, Bitner L, Cho H, Young RJ, Francis JH, Rampal R, Lacouture M, Brody LA, Ozkaya N, Dogan A, Rosen N, Iasonos A, Abdel-Wahab O, Hyman DM | ||||||||||||
| Title | Efficacy of MEK inhibition in patients with histiocytic neoplasms. | ||||||||||||
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| Abstract Text | Histiocytic neoplasms are a heterogeneous group of clonal haematopoietic disorders that are marked by diverse mutations in the mitogen-activated protein kinase (MAPK) pathway1,2. For the 50% of patients with histiocytosis who have BRAFV600 mutations3-5, RAF inhibition is highly efficacious and has markedly altered the natural history of the disease6,7. However, no standard therapy exists for the remaining 50% of patients who lack BRAFV600 mutations. Although ERK dependence has been hypothesized to be a consistent feature across histiocytic neoplasms, this remains clinically unproven and many of the kinase mutations that are found in patients who lack BRAFV600 mutations have not previously been biologically characterized. Here we show ERK dependency in histiocytoses through a proof-of-concept clinical trial of cobimetinib, an oral inhibitor of MEK1 and MEK2, in patients with histiocytoses. Patients were enrolled regardless of their tumour genotype. In parallel, MAPK alterations that were identified in treated patients were characterized for their ability to activate ERK. In the 18 patients that we treated, the overall response rate was 89% (90% confidence interval of 73-100). Responses were durable, with no acquired resistance to date. At one year, 100% of responses were ongoing and 94% of patients remained progression-free. Cobimetinib treatment was efficacious regardless of genotype, and responses were observed in patients with ARAF, BRAF, RAF1, NRAS, KRAS, MEK1 (also known as MAP2K1) and MEK2 (also known as MAP2K2) mutations. Consistent with the observed responses, the characterization of the mutations that we identified in these patients confirmed that the MAPK-pathway mutations were activating. Collectively, these data demonstrate that histiocytic neoplasms are characterized by a notable dependence on MAPK signalling-and that they are consequently responsive to MEK inhibition. These results extend the benefits of molecularly targeted therapy to the entire spectrum of patients with histiocytosis. | ||||||||||||
| Molecular Profile | Treatment Approach |
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| Gene Name | Source | Synonyms | Protein Domains | Gene Description | Gene Role |
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| Therapy Name | Drugs | Efficacy Evidence | Clinical Trials |
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| Drug Name | Trade Name | Synonyms | Drug Classes | Drug Description |
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| Gene | Variant | Impact | Protein Effect | Variant Description | Associated with drug Resistance |
|---|---|---|---|---|---|
| BRAF | N486_T491delinsK | indel | gain of function | BRAF N486_T491delinsK results in a deletion of six amino acids in the protein kinase domain of the Braf protein from amino acids 486 to 491, combined with the insertion of a lysine (K) at the same site (UniProt.org). N486_A491delinsK confers a gain of function to Braf, as indicated by increased ERK activation and transformation of cultured cells (PMID: 30867592). | |
| MAP2K1 | P105_I107del | deletion | unknown | MAP2K1 P105_I107del results in the deletion of three amino acids in the protein kinase domain of the Map2k1 protein from amino acids 105 to 107 (UniProt.org). P105_I107del has been identified in the scientific literature (PMID: 30867592), but has not been biochemically characterized and therefore, its effect on Map2k1 protein function is unknown (PubMed, Nov 2024). |
| Molecular Profile | Indication/Tumor Type | Response Type | Therapy Name | Approval Status | Evidence Type | Efficacy Evidence | References |
|---|---|---|---|---|---|---|---|
| BRAF N486_T491delinsK | Advanced Solid Tumor | predicted - sensitive | Cobimetinib | Preclinical - Cell culture | Actionable | In a preclinical study, Cotellic (cobimetinib) inhibited viability of transformed cells expressing BRAF N486_T491delinsK in culture (PMID: 30867592). | 30867592 |
| BRAF V600E | lymphatic system cancer | predicted - sensitive | Cobimetinib | Case Reports/Case Series | Actionable | In a Phase II trial, treatment with Cotellic (cobimetinib) in patients with histiocytic neoplasms resulted in a PET overall response rate of 89% (16/18), with complete response in 72% (13/18) and partial response in 17% (3/18), and resulted in stable disease in 6% (1/18) of patients, including 1 partial response and 3 complete responses in 4 patients with Erdheim-Chester disease harboring BRAF V600E (PMID: 30867592; NCT01953926). | 30867592 |
| MAP2K1 P124L | lymphatic system cancer | predicted - sensitive | Cobimetinib | Case Reports/Case Series | Actionable | In a Phase II trial, treatment with Cotellic (cobimetinib) in patients with histiocytic neoplasms resulted in a PET overall response rate of 89% (16/18), with complete response in 72% (13/18) and partial response in 17% (3/18), and resulted in stable disease in 6% (1/18) of patients, including a complete response in a patient with mixed histiocytosis harboring MAP2K1 P124L (PMID: 30867592; NCT01953926). | 30867592 |
| MAP2K1 Q56P | Erdheim-Chester disease | predicted - sensitive | Cobimetinib | Case Reports/Case Series | Actionable | In a Phase II trial, treatment with Cotellic (cobimetinib) in patients with histiocytic neoplasms resulted in a PET overall response rate of 89% (16/18), with complete response in 72% (13/18) and partial response in 17% (3/18), and stable disease in 6% (1/18) of patients, including a complete response in a patient with Erdheim-Chester disease harboring MAP2K1 Q56P (PMID: 30867592; NCT01953926). | 30867592 |
| MAP2K1 P105_I107del | lymphatic system cancer | predicted - sensitive | Cobimetinib | Case Reports/Case Series | Actionable | In a Phase II trial, treatment with Cotellic (cobimetinib) in patients with histiocytic neoplasms resulted in a PET overall response rate of 89% (16/18), with complete response in 72% (13/18) and partial response in 17% (3/18), and resulted in stable disease in 6% (1/18) of patients, including a complete response in a patient with Erdheim-Chester disease harboring MAP2K1 P105_I107del (PMID: 30867592; NCT01953926). | 30867592 |
| MAP2K1 P124Q | lymphatic system cancer | predicted - sensitive | Cobimetinib | Case Reports/Case Series | Actionable | In a Phase II trial, treatment with Cotellic (cobimetinib) in patients with histiocytic neoplasms resulted in a PET overall response rate of 89% (16/18), with complete response in 72% (13/18) and partial response in 17% (3/18), and resulted in stable disease in 6% (1/18) of patients, including a complete response in a patient with Erdheim-Chester disease harboring MAP2K1 P124Q (PMID: 30867592; NCT01953926). | 30867592 |
| BRAF N486_T491delinsK | lymphatic system cancer | predicted - sensitive | Cobimetinib | Case Reports/Case Series | Actionable | In a Phase II trial, treatment with Cotellic (cobimetinib) in patients with histiocytic neoplasms resulted in a PET overall response rate of 89% (16/18), with complete response in 72% (13/18) and partial response in 17% (3/18), and resulted in stable disease in 6% (1/18) of patients, including a complete response in a patient with Langerhans cell histiocytosis harboring BRAF N486_T491delinsK (PMID: 30867592; NCT01953926). | 30867592 |