Farnesyltransferase Inhibitors Research Articles

Phase 2 trial of the farnesyltransferase inhibitor tipifarnib for relapsed/refractory peripheral T-cell lymphoma

AbstractA phase 2, international, open-label, nonrandomized, single-arm trial was conducted to evaluate the efficacy and safety of tipifarnib, a farnesyltransferase inhibitor, as monotherapy for relapsed/refractory peripheral T-cell lymphoma (PTCL) and to evaluate tumor mutation profile as a biomarker of response. Adults with relapsed/refractory PTCL received tipifarnib 300 mg orally twice daily for 21 days in a 28-day cycle. The primary end point was objective response rate (ORR); secondary end points included ORR, progression-free survival (PFS), duration of response (DOR), and adverse events (AEs) in specific subtypes. Sixty-five patients with PTCL were enrolled: n = 38 angioimmunoblastic T-cell lymphoma (AITL), n = 25 PTCL not otherwise specified, and n = 2 other T-cell lymphomas. The ORR was 39.7% (95% confidence interval [CI], 28.1-52.5) in all patients and 56.3% (95% CI, 39.3-71.8) for AITL. Median PFS was 3.5 months overall (954% CI, 2.1-4.4), and 3.6 months (95% CI, 1.9-8.3) for AITL. Median DOR was 3.7 months (95% CI, 2.0-15.3), and greatest in patients with AITL (7.8 months; 95% CI, 2.0-16.3). The median overall survival was 32.8 months (95% CI, 14.4 to not applicable). Tipifarnib-related hematologic AEs were manageable and included neutropenia (43.1%), thrombocytopenia (36.9%), and anemia (30.8%); other tipifarnib-related AEs included nausea (29.2%) and diarrhea (27.7%). One treatment-related death occurred. Mutations in RhoA, DNMT3A, and IDH2 were seen in 60%, 33%, and 27%, respectively, in the AITL tipifarnib responder group vs 36%, 9%, and 9% in the nonresponder group. Tipifarnib monotherapy demonstrated encouraging clinical activity in heavily pretreated relapsed/refractory PTCL, especially in AITL, with a manageable safety profile. This trial was registered at www.ClinicalTrials.gov as #NCT02464228.

Current Pathophysiological and Therapeutic Options for Children with Hutchinson Gilford Syndrome

Hutchinson-Gilford-Progeria syndrome (HGPS) cannot, to date, be treated causally. Therapy for affected children focus on alleviating the symptoms, treating secondary diseases and preventing complications such as strokes or heart attacks. Various medications and physiotherapeutic methods are primarily available for this extremely rare pediatric genetic disease. Lonafarnib, a farnesyltransferase inhibitor, has been used for the treatment of progeria in children since 2022, which can extend the life of children with HGPS up to 4 years. Farnesyltransferase inhibitors are able to block an enzyme that is involved in progerin processing. Progerin is the altered protein that occurs in HGPS due to the spelling mistake in the lamin A gene and accumulates within the cell nucleus envelope. As a result, the envelope is weakened and the cell nucleus becomes deformed. The spectrum of therapies includes progerin-targeting strategies on one hand and on therapies to alleviate the tremendous effects by progerin. Research focus on different new targets in the management of HGPS-like the farnesyltransferase inhibitor lonafarnib, Acetyltransferase NAT10-inhibitors, KAT 6a/b and -7 inhibitors, paclitaxel, small molecule ICMT-inhibitors, exportin CRM-1 Inhibitors, progerin-lamin A binding inhibitors (Progerinin), Ghrelin, micro-RNA inhibitors, doxycycline and the regulation of rapamycin complex 1 (mTORC1). This manuscript analyses these new therapeutic targets and pathophysiological aspects in a review manuscript.

KRAS G12C inhibitor combination therapies: current evidence and challenge.

Although KRAS G12C inhibitors have proven that KRAS is a "druggable" target of cancer, KRAS G12C inhibitor monotherapies have demonstrated limited clinical efficacy due to primary and acquired resistance mechanisms. Multiple combinations of KRAS G12C inhibitors with other targeted therapies, such as RTK, SHP2, and MEK inhibitors, have been investigated in clinical trials to overcome the resistance. They have demonstrated promising efficacy especially by combining KRAS G12C and EGFR inhibitors for KRAS G12C-mutated colorectal cancer. Many clinical trials of combinations of KRAS G12C inhibitors with other targeted therapies, such as SOS1, ERK, CDK4/6, and wild-type RAS, are ongoing. Furthermore, preclinical data have suggested additional promising KRAS G12C combinations with YAP/TAZ-TEAD inhibitors, FAK inhibitors, and farnesyltransferase inhibitors. The combinations of KRAS G12C inhibitors with immunotherapies and chemotherapies have also been investigated, and the preliminary results were reported. More recently, KRAS-targeted therapies not limited to KRAS G12C are being developed, potentially broadening the treatment landscape of KRAS-mutated cancers. Rationally combining KRAS inhibitors with other therapeutics is likely to play a significant role in future treatment for KRAS-mutated solid tumors.

Intervention for critical aortic stenosis in Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford Progeria Syndrome (HGPS) is an ultra-rare genetic premature aging disease that is historically fatal in teenage years, secondary to severe accelerated atherosclerosis. The only approved treatment is the farnesyltransferase inhibitor lonafarnib, which improves vascular structure and function, extending average untreated lifespan of 14.5 years by 4.3 years (30%). With this longer lifespan, calcific aortic stenosis (AS) was identified as an emerging critical risk factor for cardiac death in older patients. Intervention to relieve critical AS has the potential for immediate improvement in healthspan and lifespan. However, HGPS patient-device size mismatch, pervasive peripheral arterial disease, skin and bone abnormalities, and lifelong failure to thrive present unique challenges to intervention. An international group of experts in HGPS, pediatric and adult cardiology, cardiac surgery, and pediatric critical care convened to identify strategies for successful treatment. Candidate procedures were evaluated by in-depth examination of 4 cases that typify HGPS clinical pathology. Modified transcatheter aortic valve replacement (TAVR) and left ventricular Apico-Aortic Conduit (AAC) placement were deemed high risk but viable options. Two cases received TAVR and 2 received AAC post-summit. Three were successful and 1 patient died perioperatively due to cardiovascular disease severity, highlighting the importance of intervention timing and comparative risk stratification. These breakthrough interventions for treating critical aortic stenosis in HGPS patients could rewrite the current clinical perspective on disease course by greatly improving late-stage quality of life and increasing lifespan. Expanding worldwide medical and surgical competency for this ultra-rare disease through expert information-sharing could have high impact on treatment success.

Targeting NRAS via miR-1304-5p or farnesyltransferase inhibition confers sensitivity to ALK inhibitors in ALK-mutant neuroblastoma

Targeting Anaplastic lymphoma kinase (ALK) is a promising therapeutic strategy for aberrant ALK-expressing malignancies including neuroblastoma, but resistance to ALK tyrosine kinase inhibitors (ALK TKI) is a distinct possibility necessitating drug combination therapeutic approaches. Using high-throughput, genome-wide CRISPR-Cas9 knockout screens, we identify miR-1304-5p loss as a desensitizer to ALK TKIs in aberrant ALK-expressing neuroblastoma; inhibition of miR-1304-5p decreases, while mimics of this miRNA increase the sensitivity of neuroblastoma cells to ALK TKIs. We show that miR-1304-5p targets NRAS, decreasing cell viability via induction of apoptosis. It follows that the farnesyltransferase inhibitor (FTI) lonafarnib in addition to ALK TKIs act synergistically in neuroblastoma, inducing apoptosis in vitro. In particular, on combined treatment of neuroblastoma patient derived xenografts with an FTI and an ALK TKI complete regression of tumour growth is observed although tumours rapidly regrow on cessation of therapy. Overall, our data suggests that combined use of ALK TKIs and FTIs, constitutes a therapeutic approach to treat high risk neuroblastoma although prolonged therapy is likely required to prevent relapse.

Long-term Survival in a WHO Grade 4 IDH-mutant Astrocytoma Using a Farnesyltransferase Inhibitor in Combination with Temozolomide (P4-5.006)

Long-term Survival in a WHO Grade 4 IDH-mutant Astrocytoma Using a Farnesyltransferase Inhibitor in Combination with Temozolomide (P4-5.006)

Drug repositioning and ovarian cancer, a study based on Mendelian randomisation analysis.

The role of drug repositioning in the treatment of ovarian cancer has received increasing attention. Although promising results have been achieved, there are also major controversies. In this study, we conducted a drug-target Mendelian randomisation (MR) analysis to systematically investigate the reported effects and relevance of traditional drugs in the treatment of ovarian cancer. The inverse-variance weighted (IVW) method was used in the main analysis to estimate the causal effect. Several MR methods were used simultaneously to test the robustness of the results. By screening 31 drugs with 110 targets, FNTA, HSPA5, NEU1, CCND1, CASP1, CASP3 were negatively correlated with ovarian cancer, and HMGCR, PLA2G4A, ITGAL, PTGS1, FNTB were positively correlated with ovarian cancer. Statins (HMGCR blockers), lonafarnib (farnesyltransferase inhibitors), the anti-inflammatory drug aspirin, and the anti-malarial drug adiponectin all have potential therapeutic roles in ovarian cancer treatment.

Abstract CT163: FIT-001: A phase 1 clinical trial of the farnesyl transferase inhibitor KO-2806 alone or as part of combination therapy for advanced solid tumors

Abstract Background: Farnesyl transferase inhibitors (FTIs) block post-translational modification of RAS and other farnesylated proteins. HRAS-driven tumors are highly sensitive to FTI treatment. Recent clinical trials (NCT03719690, NCT02383927) of the FTI, tipifarnib, in patients with HRAS-mutant (HRAS-m) head and neck squamous cell carcinoma harboring high variant allele frequency mutations (VAF ≥20%), showed objective response rates of up to 50% and favorable long-term outcomes. KO-2806 is a next-generation FTI that has increased potency and improved pharmacokinetic properties. In preclinical studies, KO-2806 has been shown to: (1) enhance tumor growth inhibition of tyrosine kinase inhibitors, including cabozantinib, in multiple clear cell renal cell carcinoma (ccRCC) cell line- and patient-derived xenograft models; and (2) enhance activity of KRAS inhibitors, including adagrasib, in KRAS mutant non-small cell lung cancer (NSCLC), colorectal cancer (CRC), and pancreatic ductal adenocarcinoma (PDAC) mouse models. These preclinical data support clinical investigation of KO-2806 alone and in combination therapy. Study Design: FIT-001 is a first-in-human, multicenter, open-label clinical trial that will evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics (Pd), and preliminary antitumor activity of KO-2806 as monotherapy or in combination therapy in advanced solid tumors (KO-2806-001; NCT06026410). Up to 270 patients will be enrolled in phase 1a and phase 1b combined across 50 sites. Phase 1a will have separate monotherapy and combination dose-escalation arms. As monotherapy, the study will enroll patients with N/K/HRAS alterations in specific solid tumor types, such as NSCLC, CRC, and PDAC, who are refractory to standard-of-care therapies. KO-2806 and cabozantinib will be combined in patients with advanced or metastatic ccRCC who progressed on ≥1 prior line of immunotherapy-based systemic therapy; KO-2806 and adagrasib will be combined in patients with KRAS-G12C mutant locally advanced or metastatic NSCLC who received ≥1 prior systemic therapy. On the basis of emerging data from phase 1a, two Pd cohorts (n≤12) with mandatory pre- and on-treatment tumor biopsies may be enrolled. In each Phase 1b dose expansion, patients will receive the recommended phase 2 dose [RP2D] of KO-2806 with cabozantinib (in ccRCC) or adagrasib (in NSCLC), or will be randomized by dose if 2 potential KO-2806 RP2Ds are identified for a combination. Other combination arms may also be considered. The study began accrual in October 2023. Citation Format: Glenn J. Hanna, Douglas R. Adkins, Jacob S. Thomas, Justine Y. Bruce, Manish R. Patel, Guru Sonpavde, Jason Henry, Nawal Bendris, Zijing Zhang, Amitava Mitra, Amaya Gascó, Andrew Saunders, Stephen Dale. FIT-001: A phase 1 clinical trial of the farnesyl transferase inhibitor KO-2806 alone or as part of combination therapy for advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT163.

Abstract LB220: Farnesyltransferase inhibitors show synergistic anticancer effects in combination with novel KRAS G12C inhibitors

Abstract Background. Farnesyltransferase inhibitors (FTI) failed as monotherapies for various cancer types until the discovery of their potency in HRAS mutant human head and neck and bladder cancers. On the other hand, RAS mutant cancers have been a great challenge for cancer research until the discoveries and approvals of several KRAS-G12C allele specific inhibitors. However, G12C inhibitors were effective mainly in lung cancer and de novo and acquired resistance prompted the development of various combinational modalities including immunotherapy as well as SOS- and SHP2-inhibitors. Based on in-silico analysis of drug sensitivities of KRAS mutant cancer cell lines treated with various drugs including FTIs, we have explored the possibility of the combination of FTIs with KRAS inhibitors.Methods. Clinically approved farnesyl-transferase inhibitors (tipifarnib and lonafarnib) were combined with, novel KRAS G12C inhibitors (sotorasib and adagrasib) using human lung-, pancreatic and colorectal- adenocarcinoma cells in vitro and in vivo. Antitumoral effects were evaluated for cell proliferation, apoptosis and migratory activity. Mechanisms of action were investigated by immunoblot analyzes of various farnesylated proteins, RAS activation and signaling, videomicroscopy and also by histopathology of xenograft tumors. Results. Synergistic anticancer effects were observed upon the combination of FTIs with G12C inhibitors in KRAS G12C mutant human cancer cell lines in vitro. We found that the combination interfered with the compensatory re-activation of HRAS, farnesylation of RHEB in the PI3K/mTOR pathway and lamin. Furthermore, we observed enhanced efficacy of sotorasib upon combination with tipifarnib in the xenograft models of lung adenocarcinoma affecting mitotic- and apoptotic rates and inducing necrosis.Discussion. Our findings suggest the potential clinical applicability of the combination of KRAS-G12C inhibitors and farnesyl-transferase inhibitors. Furthermore, our preliminary data suggest that the synergistic effect of FTIs on KRAS-G12C inhibitors can be projected to G12D inhibitors as well. Citation Format: Jozsef Timar, Marcell Baranyi, Eszter Molnar, Ivan Randelovic, Mihaly Cserepes, Jozsef Tovari, Balazs Hegedus. Farnesyltransferase inhibitors show synergistic anticancer effects in combination with novel KRAS G12C inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB220.

Genetic and pharmacological modulation of lamin Afarnesylation determines its function and turnover.

Hutchinson-Gilford Progeria syndrome (HGPS) is a severe premature ageing disorder caused by a 50 amino acid truncated (Δ50AA) and permanently farnesylated lamin A (LA) mutant called progerin. On a cellular level, progerin expression leads to heterochromatin loss, impaired nucleocytoplasmic transport, telomeric DNA damage and a permanent growth arrest called cellular senescence. Although the genetic basis for HGPS has been elucidated 20 years ago, the question whether the Δ50AA or the permanent farnesylation causes cellular defects has not been addressed. Moreover, we currently lack mechanistic insight into how the only FDA-approved progeria drug Lonafarnib, a farnesyltransferase inhibitor (FTI), ameliorates HGPS phenotypes. By expressing a variety of LA mutants using a doxycycline-inducible system, and in conjunction with FTI, we demonstrate that the permanent farnesylation, and not the Δ50AA, is solely responsible for progerin-induced cellular defects, as well as its rapid accumulation and slow clearance. Importantly, FTI does not affect clearance of progerin post-farnesylation and we demonstrate that early, but not late FTI treatment prevents HGPS phenotypes. Collectively, our study unravels the precise contributions of progerin's permanent farnesylation to its turnover and HGPS cellular phenotypes, and how FTI treatment ameliorates these. These findings are applicable to other diseases associated with permanently farnesylated proteins, such as adult-onset autosomal dominant leukodystrophy.

Thioxanthone-based ionic liquid as photocatalyst for a tandem cyclization reaction to synthesize pyrroloquinolinones

Visible light catalysis provides an important platform for developing green and sustainable catalytic processes. However, traditional photosensitizers have limited their application due to their inherent limitations. Due to the structural stability and recyclability of ionic liquids (ILs), a bifunctional catalyst TXIL-Ni was designed and synthesized by introducing the photosensitizer thioxanthone (TX) and transition metal Ni(II) into ILs. TXIL-Ni exhibited remarkable photocatalytic activity for C7–H acylation of indolines to efficiently synthesize pyrroloquinolinone derivatives by a tandem cyclization reaction of decarboxylation acylation and Claisen-Schmidt condensation. The protocol provided a new strategy for the synthesis of the natural product Viridicatol and the key intermediate of farnesyltransferase inhibitors. The experimental results indicated that thioxanthone-based ionic liquid TXIL-Ni as a synergistic photocatalyst has the advantages of mild reaction conditions, recyclability, and atomic economy. This provides a new solution for the design of multifunctional and reusable catalysts.

Drug repurposing screen identifies lonafarnib as respiratory syncytial virus fusion protein inhibitor.

Respiratory syncytial virus (RSV) is a common cause of acute lower respiratory tract infection in infants, older adults and the immunocompromised. Effective directly acting antivirals are not yet available for clinical use. To address this, we screen the ReFRAME drug-repurposing library consisting of 12,000 small molecules against RSV. We identify 21 primary candidates including RSV F and N protein inhibitors, five HSP90 and four IMPDH inhibitors. We select lonafarnib, a licensed farnesyltransferase inhibitor, and phase III candidate for hepatitis delta virus (HDV) therapy, for further follow-up. Dose-response analyses and plaque assays confirm the antiviral activity (IC50: 10-118 nM). Passaging of RSV with lonafarnib selects for phenotypic resistance and fixation of mutations in the RSV fusion protein (T335I and T400A). Lentiviral pseudotypes programmed with variant RSV fusion proteins confirm that lonafarnib inhibits RSV cell entry and that these mutations confer lonafarnib resistance. Surface plasmon resonance reveals RSV fusion protein binding of lonafarnib and co-crystallography identifies the lonafarnib binding site within RSV F. Oral administration of lonafarnib dose-dependently reduces RSV virus load in a murine infection model using female mice. Collectively, this work provides an overview of RSV drug repurposing candidates and establishes lonafarnib as a bona fide fusion protein inhibitor.

Farnesyl-transferase inhibitors show synergistic anticancer effects in combination with novel KRAS-G12C inhibitors

BackgroundInhibition of mutant KRAS challenged cancer research for decades. Recently, allele-specific inhibitors were approved for the treatment of KRAS-G12C mutant lung cancer. However, de novo and acquired resistance limit their efficacy and several combinations are in clinical development. Our study shows the potential of combining G12C inhibitors with farnesyl-transferase inhibitors.MethodsCombinations of clinically approved farnesyl-transferase inhibitors and KRAS G12C inhibitors are tested on human lung, colorectal and pancreatic adenocarcinoma cells in vitro in 2D, 3D and subcutaneous xenograft models of lung adenocarcinoma. Treatment effects on migration, proliferation, apoptosis, farnesylation and RAS signaling were measured by histopathological analyses, videomicroscopy, cell cycle analyses, immunoblot, immunofluorescence and RAS pulldown.ResultsCombination of tipifarnib with sotorasib shows synergistic inhibitory effects on lung adenocarcinoma cells in vitro in 2D and 3D. Mechanistically, we present antiproliferative effect of the combination and interference with compensatory HRAS activation and RHEB and lamin farnesylation. Enhanced efficacy of sotorasib in combination with tipifarnib is recapitulated in the subcutaneous xenograft model of lung adenocarcinoma. Finally, combination of additional KRAS G1C and farnesyl-transferase inhibitors also shows synergism in lung, colorectal and pancreatic adenocarcinoma cellular models.DiscussionOur findings warrant the clinical exploration of KRAS-G12C inhibitors in combination with farnesyl-transferase inhibitors.

Effect of β-Estradiol on Adipogenesis in a 3T3-L1 Cell Model of Prelamin A Accumulation.

The accumulation of farnesylated prelamin A has been suggested as one of the mechanisms responsible for the loss of fat in type 2 familial partial lipodystrophy due to variants in the LMNA gene. In this rare disease, fat loss appears in women after puberty, affecting sex-hormone-dependent anatomical areas. This study investigated the impact of 17-β-estradiol on adipogenesis in murine preadipocytes subjected to a pharmacologically induced accumulation of farnesylated and non-farnesylated prelamin A. To induce the accumulation of non-farnesylated or farnesylated prelamin A, 3T3-L1 cells were treated with the farnesyltransferase inhibitor 277 or the methyltransferase inhibitor N-acetyl-S-farnesyl-l-cysteine methylester. Subsequently, the cells were induced to undergo adipocyte differentiation in the presence or absence of 17-β-estradiol. Prelamin A accumulation was assessed through immunofluorescence, while real-time PCR and Western blot techniques were used to quantify several adipogenic genes and evaluate protein levels, respectively. The results showed that 17-β-estradiol increased adipogenesis, although the combination of this hormone plus farnesylated prelamin A led to a reduction in the number of mature adipocytes and the expression of the different genes involved in adipogenesis. In conclusion, the influence of farnesylated prelamin A accumulation on adipogenesis manifested only in the presence of estradiol. These in vitro findings suggest a potential mechanism that could explain the characteristic phenotype in women suffering type 2 familial partial lipodystrophy.

Evolutionary dynamics of tipifarnib in HRAS mutated head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a highly prevalent malignancy worldwide, with a significant proportion of patients developing recurrent and/or metastatic (R/M) disease. Despite recent advances in therapy, the prognosis for patients with advanced HNSCC remains poor. Here, we present the case of a patient with recurrent metastatic HNSCC harboring an HRAS G12S mutation who achieved a durable response to treatment with tipifarnib, a selective inhibitor of farnesyltransferase. The patient was a 48-year-old woman who had previously received multiple lines of therapy with no significant clinical response. However, treatment with tipifarnib resulted in a durable partial response that lasted 8 months. Serial genomic and transcriptomic analyses demonstrated upregulation of YAP1 and AXL in metastatic lesions compared with the primary tumor, the evolution of the tumor microenvironment from an immune-enriched to a fibrotic subtype with increased angiogenesis, and activation of the PI3K/AKT/mTOR pathway in tipifarnib treatment. Lastly, in HRAS-mutated PDXs and in the syngeneic HRAS model, we demonstrated that tipifarnib efficacy is limited by activation of the AKT pathway, and dual treatment with tipifarnib and the PI3K inhibitor, BYL719, resulted in enhanced anti-tumor efficacy. Our case study highlights the potential of targeting HRAS mutations with tipifarnib in R/M HNSCC and identifies potential mechanisms of acquired resistance to tipifarnib, along with immuno-, chemo-, and radiation therapy. Preclinical results provide a firm foundation for further investigation of drug combinations of HRAS-and PI3K -targeting therapeutics in R/M HRAS-driven HNSCC.

New indazole-indolizine-triazine hybrid molecules with farnesyltransferase inhibitory activity

A new series of indazole-indolizine-triazine hybrid molecules was obtained by [3 + 2] cycloaddition reaction between newly synthesized nitrogen ylides with indazole skeleton and previously reported dipolarophile 2‐ethynyl‐4,6‐dimethoxy‐1,3,5‐triazine and fully characterized. The biological evaluation of hybrids revealed good antitumor growth inhibitory activity against UO-31 renal cancer cell line for the (1H-indazole-1-yl)(1-(4,6-dimethoxy-1,3,5-triazin-2-yl)-7-methylindolizin-3-yl)methanone derivative 7a. Also, for the same compound, a moderate farnesyltransferase inhibitory activity (IC50 = 52.50 ± 16.07 µM) was observed. However, the best result as farnesyltransferase inhibitor of the series was registered for the 5-bromoindazole substituted analogue 7e (IC50 = 27.08 ± 4.93 µM).

Synergistic Suppression of NF1 Malignant Peripheral Nerve Sheath Tumor Cell Growth in Culture and Orthotopic Xenografts by Combinational Treatment with Statin and Prodrug Farnesyltransferase Inhibitor PAMAM G4 Dendrimers.

Neurofibromatosis type 1 (NF1) is a disorder in which RAS is constitutively activated due to the loss of the Ras-GTPase-activating activity of neurofibromin. RAS must be prenylated (i.e., farnesylated or geranylgeranylated) to traffic and function properly. Previous studies showed that the anti-growth properties of farnesyl monophosphate prodrug farnesyltransferase inhibitors (FTIs) on human NF1 malignant peripheral nerve sheath tumor (MPNST) cells are potentiated by co-treatment with lovastatin. Unfortunately, such prodrug FTIs have poor aqueous solubility. In this study, we synthesized a series of prodrug FTI polyamidoamine generation 4 (PAMAM G4) dendrimers that compete with farnesyl pyrophosphate for farnesyltransferase (Ftase) and assessed their effects on human NF1 MPNST S462TY cells. The prodrug 3-tert-butylfarnesyl monophosphate FTI-dendrimer (i.e., IG 2) exhibited improved aqueous solubility. Concentrations of IG 2 and lovastatin (as low as 0.1 μM) having little to no effect when used singularly synergistically suppressed cell proliferation, colony formation, and induced N-RAS, RAP1A, and RAB5A deprenylation when used in combination. Combinational treatment had no additive or synergistic effects on the proliferation/viability of immortalized normal rat Schwann cells, primary rat hepatocytes, or normal human mammary epithelial MCF10A cells. Combinational, but not singular, in vivo treatment markedly suppressed the growth of S462TY xenografts established in the sciatic nerves of immune-deficient mice. Hence, prodrug farnesyl monophosphate FTIs can be rendered water-soluble by conjugation to PAMAM G4 dendrimers and exhibit potent anti-tumor activity when combined with clinically achievable statin concentrations.

In situ modeling of acquired resistance to RTK/RAS-pathway-targeted therapies

Intrinsic and acquired resistance limit the window of effectiveness for oncogene-targeted cancer therapies. Here, we describe an in situ resistance assay (ISRA) that reliably models acquired resistance to RTK/RAS-pathway-targeted therapies across cell lines. Using osimertinib resistance in EGFR-mutated lung adenocarcinoma (LUAD) as a model system, we show that acquired osimertinib resistance can be significantly delayed by inhibition of proximal RTK signaling using SHP2 inhibitors. Isolated osimertinib-resistant populations required SHP2 inhibition to resensitize cells to osimertinib and reduce MAPK signaling to block the effects of enhanced activation of multiple parallel RTKs. We additionally modeled resistance to targeted therapies including the KRASG12C inhibitors adagrasib and sotorasib, the MEK inhibitor trametinib, and the farnesyl transferase inhibitor tipifarnib. These studies highlight the tractability of in situ resistance assays to model acquired resistance to targeted therapies and provide a framework for assessing the extent to which synergistic drug combinations can target acquired drug resistance.

The farnesyl transferase inhibitor (FTI) lonafarnib improves nuclear morphology in ZMPSTE24-deficient fibroblasts from patients with the progeroid disorder MAD-B

ABSTRACTSeveral related progeroid disorders are caused by defective post-translational processing of prelamin A, the precursor of the nuclear scaffold protein lamin A, encoded by LMNA. Prelamin A undergoes farnesylation and additional modifications at its C-terminus. Subsequently, the farnesylated C-terminal segment is cleaved off by the zinc metalloprotease ZMPSTE24. The premature aging disorder Hutchinson Gilford progeria syndrome (HGPS) and a related progeroid disease, mandibuloacral dysplasia (MAD-B), are caused by mutations in LMNA and ZMPSTE24, respectively, that result in failure to process the lamin A precursor and accumulate permanently farnesylated forms of prelamin A. The farnesyl transferase inhibitor (FTI) lonafarnib is known to correct the aberrant nuclear morphology of HGPS patient cells and improves lifespan in children with HGPS. Importantly, and in contrast to a previous report, we show here that FTI treatment also improves the aberrant nuclear phenotypes in MAD-B patient cells with mutations in ZMPSTE24 (P248L or L425P). As expected, lonafarnib does not correct nuclear defects for cells with lamin A processing-proficient mutations. We also examine prelamin A processing in fibroblasts from two individuals with a prevalent laminopathy mutation LMNA-R644C. Despite the proximity of residue R644 to the prelamin A cleavage site, neither R644C patient cell line shows a prelamin A processing defect, and both have normal nuclear morphology. This work clarifies the prelamin A processing status and role of FTIs in a variety of laminopathy patient cells and supports the FDA-approved indication for the FTI Zokinvy for patients with processing-deficient progeroid laminopathies, but not for patients with processing-proficient laminopathies.

Abstract B023: The next-generation farnesyltransferase inhibitor KO-2806 constrains compensatory signaling reactivation to deepen responses to KRASG12D inhibition

Abstract The landmark approval of KRASG12C inhibitors toppled the decades-held notion that KRAS was undruggable, fueling the design and development of small molecules targeting other oncogenic KRAS mutants, including the most prevalent, KRASG12D. MRTX1133 is the first KRASG12D-selective inhibitor to reach the clinic, providing a much-needed therapeutic option for patients with KRASG12D-mutant tumors. Nevertheless, both preclinical MRTX1133 data and early clinical results from KRASG12C inhibitor trials suggest that responses to KRASG12D inhibition will vary widely, at least in part due to incomplete and/or transient inhibition of MAPK and mTOR signaling. We previously demonstrated that farnesyltransferase inhibitors (FTIs) can prevent adaptive resistance to PI3K inhibition by blunting compensatory reactivation of these signaling nodes. We therefore hypothesized that farnesyltransferase inhibition may similarly enhance the antitumor activity of MRTX1133 through synergistic blockade of mitogenic and survival signaling. In this study, we leveraged a panel of in vivo cell line (CDX) and patient-derived xenograft (PDX) models, in parallel with in vitro mechanistic studies, to assess the efficacy of combined KO-2806, a FTI, and MRTX1133, in controlling KRASG12D-mutant tumor growth. KO-2806 is a next-generation FTI with increased potency and improved pharmacokinetic properties relative to earlier FTI candidates and is poised to enter a first-in-human clinical trial. Given that reactivation of phospho-ERK and phospho-S6 is linked to diminished response to MRTX1133, we first probed the impact of KO-2806 on cell signaling in vitro. In KRASG12D mutant cell lines, MRTX1133 transiently inhibited both ERK and mTOR, as evidenced by decreased ERK, p90 RSK, p70 S6K, S6, and 4EBP1 phosphorylation. However, phosphorylation of these proteins rebounded partially within one day and completely by 48 hours post treatment. In contrast, when cells were co-exposed to MRTX1133 and KO-2806, robust inhibition of these pathways was maintained at 48 hours and corresponded with greater induction of apoptosis (PARP and caspase cleavage) and cell cycle arrest (ablation of Rb phosphorylation) compared to MRTX1133. These results are consistent with prior reports suggesting that durable MAPK and mTOR inhibition is required for optimal response to KRAS inhibitors. The mechanistic synergy we observed in vitro provided a strong rationale for evaluating combined MRTX1133 and KO-2806 in vivo. Across a panel of KRASG12D-mutant CDX and PDX solid tumor models, the MRTX1133/KO-2806 doublet led to deeper tumor growth inhibition compared to the single agents while remaining well tolerated in mice. We posit that KO-2806 augments the MAPK-mTOR inhibitory effects of MRTX1133 by blocking compensatory pathway reactivation, resulting in superior antitumor efficacy of the combination without amplifying toxicity. Based upon these results, combined farnesyltransferase and KRASG12D inhibition represents a promising therapeutic strategy for the treatment of KRASG12D0-mutant solid tumors. Citation Format: Alison Smith, Hetika Patel, Stacia Chan, Francis Burrows, Shivani Malik. The next-generation farnesyltransferase inhibitor KO-2806 constrains compensatory signaling reactivation to deepen responses to KRASG12D inhibition [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B023.