P1, N=104, Not yet recruiting, Bayer

Here, we identified targeting proximal receptor tyrosine kinase (RTK) signaling using the SOS1 inhibitor (SOS1i) BI-3406 as a strategy to improve responses to G12Ci treatment...Treatment with SOS1i both delayed acquired G12Ci resistance and limited the total number of resistant colonies regardless of KEAP1 and STK11 mutational status. Together, these data suggest that targeting SOS1 could be an effective strategy to both enhance G12Ci efficacy and prevent G12Ci resistance regardless of co-mutations.

In this study, we developed a potent SOS1 PROTAC SIAIS562055, which was designed by connecting a CRBN ligand to an analogue of the SOS1 inhibitor BI-3406...SIAIS562055 and BCR-ABL inhibitors synergistically enhanced inhibition of ABL phosphorylation and downstream signaling, demonstrating robust antitumor activities in both mouse xenografts and primary CML patient samples. In summary, this study suggests that PROTAC-mediated SOS1 degradation represents an effective therapeutic strategy for treating not only KRAS-mutant cancers but also BCR-ABL-harboring leukemia.

However, these inhibitors face significant challenges in clinical studies, including limited efficacy of monotherapies, safety concerns, and the necessity to enhance PK properties. Despite their excellent in vitro performance, SOS1 inhibitors must address issues related to safety, pharmacokinetics, and pharmacodynamics in clinical applications.

P1, N=71, Active, not recruiting, Boehringer Ingelheim | Trial completion date: Oct 2024 --> Apr 2025 | Trial primary completion date: Oct 2024 --> Apr 2025

Here, we assessed the antitumor responses of KRASG12C mutant lung and colorectal cancer models to combination treatment with a SOS1 inhibitor (SOS1i), BI-3406, plus the KRASG12C inhibitor, adagrasib. Knockdown of SHOC2, a MRAS complex partner, partially restored response to KRASG12Ci treatment. These results suggest KRASG12C plus SOS1i to be a promising strategy for treating both KRASG12Ci naive and relapsed KRASG12C-mutant tumors.

FDA-approved sotorasib and adagrasib provide breakthrough therapies for cancer patients with KRASG12C mutation...Further enhanced anti-proliferation activity was observed when RGT-018 was combined with MEK, KRASG12C, EGFR or CDK4/6 inhibitors...Furthermore, RGT-018 overcame the resistance to the approved KRASG12C inhibitors caused by clinically acquired KRAS mutations either as a single agent or in combination. RGT-018 displayed promising pharmacological properties for combination with targeted agents to treat a broader KRAS-driven patient population.

MRTX0902 augmented the antitumor activity of the KRAS G12C inhibitor adagrasib when dosed in combination in eight out of 12 KRAS G12C-mutant human non-small cell lung cancer and colorectal cancer xenograft models. Lastly, combined vertical inhibition of RTK/MAPK pathway signaling by MRTX0902 with inhibitors of EGFR or RAF/MEK led to greater downregulation of pathway signaling and improved antitumor responses in KRAS-MAPK pathway-mutant models. These studies demonstrate the potential clinical application of dual inhibition of SOS1 and KRAS G12C and additional SOS1 combination strategies that will aide in the understanding of SOS1 and RTK/MAPK biology in targeted cancer therapy.

Oral administration of HH0043 resulted in a significant tumor inhibitory effect in a subcutaneous KRAS G12C-mutated NCI-H358 (human lung cancer cell line) xenograft mouse model, and the tumor inhibitory effect of HH0043 was superior to that of BI-3406 at the same dose (total growth inhibition, TGI: 76% vs 49%). On the basis of these results, HH0043, with a novel 1,7-naphthyridine scaffold that is distinct from currently reported SOS1 inhibitors, is nominated as the lead compound for this discovery project.

The evaluated inhibitors BI-3406, trametinib and BKM120 showed synergistic effects in vitro. This combinatorial therapy reduced tumor weight more efficiently in male animals, although the drug concentrations were similar in the tumors of both sexes. These results underline the importance of sex-specific preclinical research and at the same time provide a solid basis for future studies with the tested compounds.

The addition of checkpoint blockade to SOS1i+MEKi combination resulted in tumor free mice with established immune memory. Our data suggests that KRAS inhibition affects myeloid cell maturation and highlights the need for combining KRAS cancer-targeted therapy with myeloid activation to enhance and prolong anti-tumor effects.

Moreover, 11o inhibited the phosphorylation of ERK and displayed potent anti-proliferative activities against SW620, A549 and DLD-1 cells. Further optimization of 11o may provide us promising SOS1 degraders with favorable drug-like properties for developing new chemotherapies targeting KRAS-driven cancers.

An in silico drug-likeness assessment suggested that the compound has moderately favorable drug-like properties and pharmacokinetic characteristics. Altogether, our findings strongly support that, characterized by the distinctive binding modes, the recognition of novel skeletons from the carboxylic acid series could be candidates for developing promising SOS1 inhibitors.

MRTX0902 augmented the antitumor activity of the KRAS G12C inhibitor adagrasib when dosed in combination in eight out of twelve KRAS G12C-mutant human non-small cell lung cancer (NSCLC) and colorectal cancer (CRC) xenograft models. Lastly, combined vertical inhibition of RTK/MAPK pathway signaling by MRTX0902 with inhibitors of EGFR or RAF/MEK led to greater downregulation of pathway signaling and improved antitumor responses in KRAS-MAPK pathway-mutant models. These studies demonstrate the potential clinical application of dual inhibition of SOS1 and KRAS G12C and additional SOS1 combination strategies that will aide in the understanding of SOS1 and RTK/MAPK biology in targeted cancer therapy.

P1, N=71, Active, not recruiting, Boehringer Ingelheim | Trial primary completion date: Mar 2024 --> Oct 2024

Comparative analysis of the average binding free energies of these predicted potent compounds with known SOS1 small molecule inhibitors revealed that the identified compounds display similar or even superior predicted binding affinities compared to the known inhibitors. These findings offer valuable insights into the potential of these compounds as candidates for further development as effective anti-cancer agents.

P1/2, N=110, Recruiting, Suzhou Zelgen Biopharmaceuticals Co.,Ltd | Not yet recruiting --> Recruiting | Initiation date: Feb 2024 --> Aug 2023

P1, N=71, Active, not recruiting, Boehringer Ingelheim | Trial completion date: Mar 2024 --> Oct 2024

P1/2, N=110, Not yet recruiting, Suzhou Zelgen Biopharmaceuticals Co.,Ltd

The SOS1 inhibitor BI-3406 enhanced the efficacy of trametinib and prevented trametinib resistance by targeting spheroid-initiating cells in KRAS-mutated LUAD and COAD cell lines that lacked PIK3CA comutations. Our findings demonstrate that vertical inhibition of RTK/RAS signaling is an effective strategy to prevent therapeutic resistance in KRAS-mutated cancers, but therapeutic efficacy is dependent on both the specific KRAS mutant and underlying comutations. Thus, selection of optimal therapeutic combinations in KRAS-mutated cancers will require a detailed understanding of functional dependencies imposed by allele-specific KRAS mutations.

P1, N=71, Active, not recruiting, Boehringer Ingelheim | Trial completion date: Sep 2023 --> Mar 2024 | Trial primary completion date: Sep 2023 --> Mar 2024

Finally, we showed that GTP-bound RAS level underwent rebound even in BI3406-sensitive PDOs with no change of KRAS downstream effector genes, thus suggesting upregulation of guanine nucleotide exchange factor as potential cellular adaptation mechanisms to SOS1 inhibition. Taken together, our results show that high SOS1/SOS2 protein expression ratio predicts sensitivity to SOS1 inhibition and support further clinical development of SOS1-targeting agents in CRC.

6c showed a favorable pharmacokinetic profile in vivo, with a bioavailability of 65.8% and exhibited potent tumor suppression in pancreas tumor xenograft models. These intriguing results suggested that 6c has the potential to be developed as a drug candidate for KRAS-driven tumors.

Here, we designed and synthesized a series of quinazoline-based compounds, and conducted subsequent evaluations of their biological activities. Among them, the comparable compounds I-2 (IC=20nM, against SOS1) I-5 (IC=18nM, against SOS1) and I-10 (IC=8.5nM, against SOS1) have kinase activity equivalent to BAY-293 (IC=6.6nM, against SOS1), and I-10 also has cell activity equivalent to BAY-293, providing a theoretical reference for subsequent related researches on SOS1 inhibitors.

Single agent SOS1 inhibition had no significant effect in the DhhCre;Nf1 mouse model of plexiform neurofibroma, but pharmacokinetics (PK)-driven combination of selumetinib with BI-3406 significantly improved tumor parameters. Significance Statement Interfering with the RAS-MAPK cascade upstream of MEK, together with MEK inhibition, augment effects of MEK inhibition on neurofibroma volume and tumor macrophages in a preclinical model system. This study emphasizes the critical role of the RAS-MAPK pathway in controlling tumor cell proliferation and the tumor microenvironment in benign neurofibromas.

P1, N=71, Active, not recruiting, Boehringer Ingelheim | Trial completion date: Feb 2023 --> Sep 2023 | Trial primary completion date: Feb 2023 --> Sep 2023

P1, N=8, Terminated, Boehringer Ingelheim | Completed --> Terminated; Sponsor decision

P1, N=8, Completed, Boehringer Ingelheim | Terminated --> Completed

P1b/2, N=1143, Recruiting, Amgen | Trial completion date: Oct 2026 --> Jun 2027 | Trial primary completion date: Aug 2024 --> Dec 2024

P1, N=7, Completed, Mirati Therapeutics Inc. | Active, not recruiting --> Completed | N=100 --> 7 | Trial completion date: Feb 2024 --> Nov 2022 | Trial primary completion date: Nov 2023 --> Nov 2022

The synthesis used the 6- and 7-OH groups of a quinazoline core as anchor points to connect lenalidomide. SOS1 degrader P7 demonstrated superior activity in inhibiting CRC PDO growth with an IC 5 times lower than that of SOS1 inhibitor BI3406. In summary, we developed new SOS1 degraders and demonstrated SOS1 degradation as a feasible therapeutic strategy for KRAS-mutant CRC.

To conclude, SOS1 may induce the EMT by the activation of the PI3K/AKT/mTOR pathway, thereby enhancing invasion, migration and metastasis of HCC cells. These findings may expose SOS1 as a new HCC therapeutic target.

P1/2, N=225, Recruiting, Mirati Therapeutics Inc. | Not yet recruiting --> Recruiting

Toxicological investigations revealed that 13c had a lower risk of sudden cardiac death than BI-3406. Overall, 13c has been under evaluation in preclinical trials.

P1/2, N=225, Not yet recruiting, Mirati Therapeutics Inc.

P1, N=71, Active, not recruiting, Boehringer Ingelheim | Trial completion date: Sep 2022 --> Feb 2023 | Trial primary completion date: Sep 2022 --> Feb 2023

We investigated the anti-tumor efficacy of two KRAS inhibitors BI-3406 (KRAS::SOS1 inhibitor) and sotorasib (KRAS G12C inhibitor) alone or in combination with MEK1/2 inhibitor trametinib and/or PI3K inhibitor buparlisib in seven PDAC cell lines. As well as directly involved in RAF/MEK/ERK pathway and PI3K/AKT pathway affect cell survival. Our current study confirmed inhibition of KRAS and its downstream pathways as a potential novel therapy for PDAC and provides fundamental data for in vivo evaluations.