The use of mutant isocitrate dehydrogenase (mIDH) inhibitors has been investigated and has shown significant improvement in survival outcomes in patients with a range of mIDH cancers, including acute myeloid leukaemia (AML), cholangiocarcinoma (CCA), glioma and conventional chondrosarcoma. In the phase 3 clinical trial ClarIDHy, patients with mIDH1 CCA treated with ivosidenib had improved overall survival (OS) compared to those treated with placebo (hazard ratio [HR]: 0.79 [95% confidence interval [CI]: 0.56-1.12]; P=0.09). In the phase 3 AGILE study, patients with mIDH1 AML treated with ivosidenib plus azacitidine showed improved OS compared to those treated with placebo plus azacitidine (HR: 0.42 [95% CI: 0.27-0.73]; P=0.001). In conventional chondrosarcoma, ivosidenib demonstrated efficacy in a phase 1 trial and the ongoing phase 3, placebo-controlled clinical trial CHONQUER will investigate the use of ivosidenib in patients with unresectable, progressive, conventional mIDH1 chondrosarcoma. The phase 3 clinical trial INDIGO explored the use of vorasidenib for the treatment of Central Nervous System World Health Organization grade 2 mIDH glioma and showed that vorasidenib had a progression-free survival benefit over placebo in previously untreated patients (HR: 0.39 [95% CI: 0.27-0.56]; P<0.0001). Across these studies, mIDH inhibitors were well-tolerated. Current efforts focus on further evaluating the efficacy and safety of mIDH inhibitors in different lines of therapy, in combination with other anti-neoplastic agents, and in other mIDH cancers.
The isocitrate dehydrogenase (IDH) family of proteins comprises three important metabolic enzymes that convert isocitrate to alpha ketoglutarate (α-KG) via oxidative decarboxylation. The IDH enzymes play important roles in epigenetic regulation, DNA repair, and cellular metabolism and biosynthesis. In mutant IDH (mIDH) cells, α-KG is converted into the functional oncometabolite 2-hydroxyglutarate (2-HG) in a process that consumes the reduced form of nicotinamide adenine dinucleotide phosphate to generate its oxidised form. 2-HG competitively inhibits α-KG from binding to the active site of histone and DNA demethylases, leading to hypermethylation, which inhibits cellular differentiation and induces tumour cell proliferation. Increased 2-HG also has other effects on cellular biology, including altered metabolism, dysregulation of gene expression, alterations in the DNA damage repair pathway, inflammation, and cell death, therefore supporting and promoting tumorigenesis. mIDH genes are associated with a variety of cancers, including but not limited to, cholangiocarcinoma, acute myeloid leukaemia, glioma, and chondrosarcoma, and the incidences of mIDH in these cancers varies and is approximately 13%, 33%, 73%, and 56%, respectively. The biological effects of mIDH are distinct in different cancers, but the reason that mIDH promotes tumour development in some tissues and not others is not clear. mIDH has no definitive prognostic impact in these cancers, except glioma, in which it is a disease-defining marker due to its distinct prognostic significance. mIDH1/2 are actionable mutations that represent therapeutic targets, however available targeted therapies to treat mIDH cancers are lacking. This article discusses mIDH genes and their importance in each of these cancers.
•A three-state partitioned survival model of GEP-NET patients was developed.•Base case ICERs for [177Lu]Lu-DOTA-TATE were under £30,000 per QALY for all comparators.•[177Lu]Lu-DOTA-TATE is cost-effective for the treatment of GEP-NETs from a NICE perspective.
Head-to-head comparisons of the efficacy of treatments for gastroenteropancreatic neuroendocrine tumours (GEP-NETs) have not yet been reported. This study used a series of matching-adjusted indirect comparisons to indirectly compare the effectiveness of [177Lu]Lu-DOTA-TATE to everolimus, sunitinib and best supportive care (BSC) for extending progression-free survival and overall survival in patients with advanced, unresectable gastrointestinal (GI)-NETs and P-NETs. The results of the main analysis suggest that after accounting for differences in key prognostic variables, the hazard of progression was 62% (hazard ratio [HR], 0.38; confidence interval [CI]95 0.25–0.58) and 65% (HR 0.35 CI95 0.21–0.59) lower in patients with GI-NETs treated with [177Lu]Lu-DOTA-TATE than in those treated with everolimus and BSC, respectively. Similarly, the hazard of progression was 64% (HR 0.36 CI95 0.18–0.70), 54% (HR 0.46 CI95 0.30–0.71) and 79–87% (HR 0.21 CI95 0.13–0.32; HR 0.13 CI95 0.08–0.22) lower in patients with P-NET treated with [177Lu]Lu-DOTA-TATE than in those treated with sunitinib, everolimus and BSC, respectively. The hazard of death was 58% (HR 0.42 CI95 0.25–0.72), 47% (HR 0.53 CI95 0.33–0.87) and 44–64% (HR 0.56 CI95 0.36–0.90; HR 0.34 CI95 0.20–0.57) lower in P-patients with NET treated with [177Lu]Lu-DOTA-TATE than in those treated with sunitinib, everolimus and BSC, respectively. While our results must be interpreted with caution given the non-randomised nature of the comparisons and the potential for residual confounding, the magnitude of the effect sizes we observe and their consistency across comparators suggest that [177Lu]Lu-DOTA-TATE may be a more effective treatment option than everolimus, sunitinib and BSC in advanced, unresectable GEP-NETs.
