Trial in Progress: Phase 1 Studies of BI 1701963, a SOS1::KRAS Inhibitor, in Combination with MEK inhibitors, Irreversible KRASG12C Inhibitors or Irinotecan Marco H. Hofmann 1* , Hengyu Lu 3 , Ulrich Duenzinger 2 , Daniel Gerlach 1 , Francesca Trapani 1 , Annette A. Machado 3 , Joseph R. Daniele 3 , Justin K. Huang 3 , Christopher A. Bristow 3 , Irene C. Waizenegger 1 , Michael Gmachl 1 , Dorothea Rudolph 1 , Christopher P. Vellano 3 , Marcelo Marotti 3 , Vitomir Vucenovic 2 , Timothy P. Heffernan 3 , Joseph R. Marszalek 3 , Mark P. Petronczki 1 and Norbert Kraut 1 0 10 20 30 40 100 200 300 400 500 1000 1500 2000 Days on treatment Tumor Volume (mm 3 ) Vehicle MRTX-849 100 mpk QDx5/wk MRTX + BI-3406 50mpk BIDx5/wk BI-3406 50 mpk BIDx5/wk Vehicle BI 1701963 MRTX-849 (100mg/kg) MRTX-849 + BI 1701963 • Trials exploring the combination of BI 1701963 with irreversible KRAS G12C inhibitors (MRTX849 and BI 1823911) will include cohorts of patients with previously treated KRAS G12C mutant NSCLC and CRC and are anticipated to begin in 2021. • NCT04627142 is a phase I dose escalation trial of BI 1701963 in combination with irinotecan patients aged ≥18 years with previously treated unresectable locally advanced or metastatic colorectal cancer (CRC) harbouring KRAS mutations. 95 patients will be enrolled in the trial which runs in China only. • Primary endpoints include dose-limiting toxicities and objective response rate. Secondary endpoints include pharmacokinetic and pharmacodynamic properties of monotherapy and combination regimens, treatment-related adverse events and preliminary efficacy. • Key inclusion criteria include activating KRAS mutation, age ≥18 years, ≥1 evaluable lesion (RECIST v1.1), ECOG PS ≤1 and adequate organ function. Key exclusion criteria include previous therapy with RAS-, MAPK- or SOS1-targeting treatments, history of retinal vein occlusion or retinopathy and decreased cardiac function. • As of March 10, 2021, 28 patients have been treated in the BI 1701963 monotherapy arm, 16 patients have been treated in the BI 1701963 + trametinib combination arm in dose escalation (Part A). 1 Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria, 2 Boehringer Ingelheim International GmbH, Ingelheim, Germany, 3 TRACTION Platform, Therapeutics Discovery Division, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA *Corresponding author: [email protected] Presented at the Virtual AACR Annual Meeting 2021 This study was funded by Boehringer Ingelheim. The authors were fully responsible for all content and editorial decisions, were involved at all stages of poster development and have approved the final version. • Our preclinical results support the positioning of SOS1::pan- KRAS inhibitors as a backbone combination partner for targeting KRAS-dependent tumors. • SOS1::pan-KRASi + MEKi combinations leads to tumor stasis or regressions in KRAS mutant models. • SOS1::pan-KRAS inhibitors sensitize KRAS G12C mutant tumors to covalent KRAS G12C inhibitors that bind to KRAS(OFF). • SOS1::pan-KRAS inhibitors sensitizes KRAS mutant cancer cells to the effects of irinotecan. • Phase I clinical trial with BI 1701963 in monotherapy and combination with MEK inhibitors (NCT04111458), KRAS G12C inhibitors or irinotecan (NCT04627142) are either ongoing or will be started in 2021. Key Findings and Conclusions Introduction (1) Phase I Clinical Trials: SOS1i + MEKi (3) Phase I Clinical Trials: SOS1i + Irinotecan • BI 1701963 is the first SOS1::pan-KRAS signaling modifier to enter phase I clinical trials both as a monotherapy as well as in combination. • Here, we present pre-clinical data showing enhanced pathway modulation and synergistic anti-tumor effects following vertical pathway inhibition of BI 1701963 in combination with: (1) Mitogen-activated protein kinase inhibitors (trametinib and BI 3011441) (2) KRAS G12C inhibitors (MRTX849 and BI 1823911) Results: SOS1::KRASi BI 1701963 (1) Pre-Clinical Results: SOS1i + MEKi #CT210 • Pre-clinical combination data supported the start of multiple phase I trials investigating the safety, tolerability, recommended dose and preliminary efficacy of BI 1701963 alone and in combination with other anti-cancer agents. • NCT04111458 is a first-in-human dose escalation and expansion trial of BI 1701963 alone and in combination with trametinib in patients aged ≥18 years with previously treated solid tumours harbouring KRAS mutations. Approximately 140 patients will be included in the trial. Parts B and C will only include patients with advanced non-small cell lung cancer (NSCLC). BI-3406 and BI1701963 are SOS1::pan-KRAS inhibitors exhibiting activity against a broad spectrum of KRAS alleles, including the major G12D/V/C and G13D oncoproteins, while sparing the interaction of KRAS with SOS2. Tool Compound B Figure 1A Normalized RLU (%DMSO) Percentage proliferation Inhibition SOS1i BI-3406 (log, M) SOS1i BI-3406 (log, M) Figure 2: SOS1i + MEKi combination exhibits differential response in pancreatic cancer PDX models. Figure 5: SOS1i + Irinotecan Combination A, Biochemical protein-protein interaction assay (Alpha Screen) between recombinant SOS1 or SOS2 and recombinant KRAS G12C or KRAS G12D conducted with increasing concentrations of the SOS1i BI-3406 B, In vitro sensitivity panel of NCI-H23 isogenic cell lines treated with BI-3406 in a 3D proliferation assay. Figure 1: SOS1i blocks the interaction of SOS1 and KRAS and thereby inhibits the proliferation of NCI-H23 isogenic cell lines carrying a KRAS G12D, G12V, G12C or G13D allele. N N O O NH F 3 C NH 2 O BI-3406 0 10 20 30 40 0 500 1000 1500 Tumor Volume (mm 3 ) Vehicle BI-406 + Trametinib Days on Treatment 0 5 10 15 20 25 0 200 400 600 800 Tumor Volume (mm 3 ) Vehicle BI-406 + Trametinib Days on Treatment PATX147 (Q61R) 0 10 20 30 40 0 200 400 600 800 1000 Tumor Volume (mm 3 ) Vehicle BI-406 + Trametinib Days on Treatment PATX216 (Q61K) 0 5 10 15 20 25 0 500 1000 1500 2000 Tumor Volume (mm 3 ) Vehicle BI-406 + Trametinib Days on Treatment PATX53 (G12D) 0 10 20 30 0 500 1000 1500 2000 2500 Tumor Volume (mm 3 ) Vehicle BI-406 + Trametinib Days on Treatment PATX124 (G12D) 0 10 20 30 40 0 500 1000 1500 2000 Tumor Volume (mm 3 ) Vehicle BI-1963 + Trametinib Days on Treatment PATX153* (G12V) 0 10 20 30 0 200 400 600 800 1000 Tumor Volume (mm 3 ) Vehicle BI-406 + Trametinib Days on Treatment PATX219B (G12D) 0 10 20 30 0 500 1000 1500 Tumor Volume (mm 3 ) Vehicle BI-406 + Trametinib Days on Treatment PATX141 (G12D) 0 10 20 30 0 500 1000 1500 Tumor Volume (mm 3 ) Vehicle BI-406 + Trametinib Days on Treatment PATX60 (G12D) 0 10 20 30 0 200 400 600 800 Tumor Volume (mm 3 ) Vehicle BI-406 + Trametinib Days on Treatment PATX110 (G12D) PATX118 (Q61H) 0 10 20 30 0 500 1000 1500 2000 Tumor Volume (mm 3 ) Days on Treatment Vehicle (n=5) BI-406 + Trametinib (n=5) Vehicle (N=10) BI-406 + Trametinib (n=10) 0 10 20 30 0 500 1000 Tumor Volume (mm 3 ) Days on Treatment Vehicle (n=8) BI-406 + Trametinib (n=8) Vehicle (n=5) BI-406 + Trametinib (n=4) PATX148 (G12D) PATX55 (Q61H) Intermediate Vehicle SOS1i + MEKi Stable Progressive Gene Signature Score Figure 3: SOS1i + MEKi combination exhibits anti-tumor response in KRAS mut colorectal cancer PDX models. A, Rationale of combining SOS1i with MEKi. B, In vivo efficacy of BI-3406 / BI 1701963 (50 mpk, BID) + trametinib (0.1 mpk, BID) in PDAC PDX models. Responses are categorized as progressive, intermediate, and stable. C, Models are sorted by first the Principal Component (PC1) of a gene signature developed by using the sum replicates, nested model, and cross-class pairwise methods based on baseline gene expression differences between the stable and progressive models. C B F3008 (CRC) 0.1 1 10 0 10 20 30 40 50 60 Rel. Tumor Volume Day Vehicle Control BI-1963, 50 mg/kg, bid lip. Irinotecan 5 mg/kg, q7d Combination Natrosol Irinotecan BI-1963 Irinotecan + BI-1963 0.00 0.25 0.50 0.75 1.00 1.25 1.50 % positive area ✱ p= 0.01 Cleaved Caspase 3 (cC3) Irinotecan Irinotecan + BI-1963 0 50 100 150 200 250 H-Score ✱✱ p=0.079 yH2AX (DNA Damage) 1 10 0 10 20 30 40 Rel. Tumor Volume LoVo CDX KRAS G13D 0.1 1 10 0 10 20 30 40 Rel. Tumor Volume Day SW620 CDX KRAS G12V MIA PaCa-2 CDX KRAS G12C A, Rationale of combining SOS1i with irinotecan B, in vivo efficacy in CDX models C, Modulation of yH2AX and cleaved caspase measured by IHC in LoVo tumor following 8 days of treatment. 0 5 10 15 20 25 0 500 1000 1500 2000 2500 3000 Tumor Volume (mm 3 ) Days on Treatment Tumor 0 20 40 60 Avg copies/positive cell -6 -4 -2 0 2 MPAS A, In vivo efficacy of BI-3406 / BI 1701963 (50 mpk, BID) + trametinib (0.1 mpk, BID) in KRAS mut CRC PDX models. B, RNAScope was evaluated on tumor samples collected from B8182 endpoint samples (4 hours post-1 st dose). A Vehicle SOS1i + MEKi DUSP6 EGR1 DUSP4 SPRY4 JUNB POL2RA B A A B C B8182 (CRC) A, Rationale combining SOS1i with KRAS G12Ci. In vivo efficacy and biomarker analysis of B, AMG 510 (30 mpk, QDx5/wk) alone or combined with BI 1701963 (50 mpk, BIDx5/wk) in B8182 model and C, MRTX849 (100 mpk, QD), BI-3406 (50 mpk, BID), and the combination in F3008 model. A B B C • Primary endpoints include dose-limiting toxicities and objective response rate. Secondary endpoints include pharmacokinetic parameters of monotherapy and combination regimens, treatment- related adverse events and preliminary efficacy. • Key inclusion criteria include previous treatment with standard fluoropyrimidine-based chemotherapy, activating KRAS mutation, age ≥18 years, ≥1 evaluable lesion (RECIST v1.1), ECOG PS ≤1 and adequate organ function. Key exclusion criteria include previous therapy with RAS-, MAPK- or SOS1-targeting treatments or irinotecan (Part B and C only), history of retinal vein occlusion or retinopathy and decreased cardiac function. • As of March 10, 2021, 4 patients have been treated in the trial. (2) Phase I Clinical Trials: SOS1i + KRASG12Ci (2) Pre-Clinical Results: SOS1i + KRASG12Ci (3) Pre-Clinical Results: SOS1i + Irinotecan Tumor DUSP6+ 0 10 20 30 40 Avg. copies/cell Vehicle MRTX-849 100mpk QDx5/wk MRTX-849+BI-3406 50mpk BIDx5/wk Tumor pHH3+ 0.0 0.5 1.0 1.5 % positive cells (3) Furthermore, the SOS1::pan-KRAS inhibitor treatment sensitizes tumor cells to increased DNA damage in combination with irinotecan. SOS1i Additional data will be presented in poster #1271, Savarese et al. Part C: Dose expansion Part B: Dose confirmation Part A: Dose escalation Monotherapy BI 1701963 Dose will be escalated until MTD / RP2D is reached or 2000 mg QD n≥3 per dosage BI 1701963 TRD 1 n=12 BI 1701963 TRD 2 n=12 Combination therapy BI 1701963 + trametinib Dose will be escalated until the MTD / RP2D or highest tested monotherapy dose (BI 1701963) or a max. of 2 mg QD (trametinib) is reached n≥3 per dosage BI 1701963 + trametinib TRD 1 n= 10 BI 1701963 + trametinib TRD 2 n= 10 If ≥1 OR observed, add n=15 patients If ≥1 OR observed, add n=15 patients was initiated after first three dose levels BI 1701963 confirmed as safe Figure 6: NCT04111458 Study Design TRD: therapeutically relevant dose; MTD: maximum tolerated dose; RP2D: recommended phase 2 dose Part C: Combination Therapy Expansion Part B: Combination Therapy Dose Escalation Part A: Monotherapy Safety Run-In BI 1701963 At least two dose levels that have been confirmed safe in the first-in- human trial monotherapy arm will be investigated n≥6 per dosage Figure 7: NCT04627142 Study Design BI 1701963 + irinotecan BI 1701963 dose will be escalated until the MTD / RP2D of the combination is reached n≥3-6 per dosage BI 1701963 + irinotecan TRD 2 n= 25 BI 1701963 + irinotecan TRD 1 n= 25 R TRD: therapeutically relevant dose; MTD: maximum tolerated dose; RP2D: recommended phase 2 dose Table 1 DUSP6 pHH3 DUSP6 mRNA MPAS Score Figure 4: SOS1i + KRAS G12Ci Combination in KRAS G12Cmut CRC PDX models 0 10 20 30 0 200 400 600 Tumor Volume (mm 3 ) Vehicle BI-406 50mpk + Tram. 0.1mpk Days on study 0 5 10 15 20 25 0 200 400 600 800 1000 Tumor Volume (mm 3 ) Vehicle BI-406 50mpk + Tram. 0.1mpk Days on study 0 5 10 15 20 0 500 1000 1500 2000 Tumor Volume (mm 3 ) Vehicle Days on study BI-1963 (50 mpk) + Tram (0.1 mpk) 0 5 10 15 20 25 0 500 1000 1500 2000 Tumor Volume (mm 3 ) Vehicle BI-406 50mpk + Tram. 0.1mpk Days on study 3D Proliferation Assay B8182 KRAS G12C C0999 KRAS G12D C1047 KRAS G12C C1035 KRAS G12V 0 50 100 150 Relative Average Copy/cell PDX: B8182 DUSP6 EGR1 DUSP6 JUNB SPRY4 Average POL2RA Vehicle BI 1701963+Trametinib Vehicle AMG-510 (30 mg/kg) AMG-510 + BI 1701963 Clinical Candidate Biochemical Protein-Protein Interaction Assay