A first-in-human phase I study of the PD-1 inhibitor, retifanlimab (INCMGA00012), in patients with advanced solid tumors (POD1UM-101)

BACKGROUND

Retifanlimab is a humanized, hinge-stabilized immunoglobulin G4κ monoclonal antibody against human programmed cell death protein 1 (PD-1). This first-in-human, phase I study assessed the safety and efficacy of retifanlimab in patients with advanced solid tumors and identified optimal dosing.

PATIENTS AND METHODS

POD1UM-101 was conducted in two parts: (i) dose escalation-evaluated retifanlimab [1 mg/kg every 2 weeks (q2w), 3 or 10 mg/kg q2w or every 4 weeks (q4w)] in patients with relapsed/refractory, unresectable, locally advanced or metastatic solid tumors; (ii) cohort expansion-biomarker-unselected tumor-specific cohorts [endometrial, cervical, sarcoma, non-small-cell lung cancer (NSCLC)] received retifanlimab 3 mg/kg q2w, and tumor-agnostic cohorts received flat dosing [375 mg every 3 weeks (q3w), or 500 and 750 mg q4w]. Primary objectives were safety and tolerability; secondary objective was efficacy in selected tumor types.

RESULTS

Thirty-seven patients were enrolled in dose escalation, 134 in PD-1 therapy-naïve tumor-specific cohort expansion (endometrial, n = 29; cervical, NSCLC, soft tissue sarcoma, each n = 35), and 45 in flat dosing (375 mg q3w, 500 and 750 mg q4w, each n = 15). No dose-limiting toxicities occurred during dose escalation; maximum tolerated dose was not reached and 3-mg/kg q2w expansion dose was selected based on safety and pharmacokinetic data. Immune-related adverse events were experienced by 40 patients (30%) in tumor-specific cohorts (most frequently hypothyroidism, hyperthyroidism, colitis, nephritis) and 6 (13%) in flat dosing (most frequently hypothyroidism, hyperthyroidism). Objective response rate (95% confidence interval) was 14% (4.8 to 30.3), 14% (3.9 to 31.7), 20% (8.4 to 36.9), and 3% (0.1 to 14.9) in advanced NSCLC, endometrial, cervical, and sarcoma tumor-specific cohorts that progressed after multiple prior systemic therapies.

CONCLUSIONS

Retifanlimab demonstrated clinical pharmacology, safety, and antitumor activity consistent with the programmed death (ligand)-1 inhibitor class. POD1UM-101 results support further exploration of retifanlimab as monotherapy and backbone immunotherapy in combination treatments, with recommended doses of 500 mg q4w and 375 mg q3w.

Durable responses to ATR inhibition with ceralasertib in tumors with genomic defects and high inflammation

BACKGROUNDPhase 1 study of ATRinhibition alone or with radiation therapy (PATRIOT) was a first-in-human phase I study of the oral ATR (ataxia telangiectasia and Rad3-related) inhibitor ceralasertib (AZD6738) in advanced solid tumors.METHODSThe primary objective was safety. Secondary objectives included assessment of antitumor responses and pharmacokinetic (PK) and pharmacodynamic (PD) studies. Sixty-seven patients received 20-240 mg ceralasertib BD continuously or intermittently (14 of a 28-day cycle).RESULTSIntermittent dosing was better tolerated than continuous, which was associated with dose-limiting hematological toxicity. The recommended phase 2 dose of ceralasertib was 160 mg twice daily for 2 weeks in a 4-weekly cycle. Modulation of target and increased DNA damage were identified in tumor and surrogate PD. There were 5 (8%) confirmed partial responses (PRs) (40-240 mg BD), 34 (52%) stable disease (SD), including 1 unconfirmed PR, and 27 (41%) progressive disease. Durable responses were seen in tumors with loss of AT-rich interactive domain-containing protein 1A (ARID1A) and DNA damage-response defects. Treatment-modulated tumor and systemic immune markers and responding tumors were more immune inflamed than nonresponding.CONCLUSIONCeralasertib monotherapy was tolerated at 160 mg BD intermittently and associated with antitumor activity.TRIAL REGISTRATIONClinicaltrials.gov: NCT02223923, EudraCT: 2013-003994-84.FUNDINGCancer Research UK, AstraZeneca, UK Department of Health (National Institute for Health Research), Rosetrees Trust, Experimental Cancer Medicine Centre.

Unbiased differential proteomic profiling between cancer-associated fibroblasts and cancer cell lines

Cancer-associated fibroblasts (CAFs) are a key component of tumors. We aimed to profile the proteome of cancer cell lines representing three common cancer types (lung, colorectal and pancreatic) and a representative CAF cell line from each tumor type to gain insight into CAF function and novel CAF biomarkers. We used isobaric labeling, liquid chromatography and mass spectrometry to evaluate the proteome of 9 cancer and 3 CAF cell lines. Of the 9460 proteins evaluated, functional enrichment analysis revealed an upregulation of N-glycan biosynthesis and extracellular matrix proteins in CAFs. 85 proteins had 16-fold higher expression in CAFs compared to cancer cells, including previously known CAF markers like fibroblast activation protein (FAP). Novel overexpressed CAF biomarkers included heat shock protein β-6 (HSPB6/HSP20) and cyclooxygenase 1 (PTGS1/COX1). SiRNA knockdown of the genes encoding these proteins did not reduce contractility in lung CAFs, suggesting they were not crucial to this function. Immunohistochemical analysis of 30 tumor samples (10 lung, 10 colorectal and 10 pancreatic) showed restricted HSPB6 and PTGS1 expression in the stroma. Therefore, we describe an unbiased differential proteome analysis of CAFs compared to cancer cells, which revealed higher expression of HSPB6 and PTGS1 in CAFs. Data are available via ProteomeXchange (PXD040360). SIGNIFICANCE: Cancer-associated fibroblasts (CAFs) are highly abundant stromal cells present in tumors. CAFs are known to influence tumor progression and drug resistance. Characterizing the proteome of CAFs could give potential insights into new stromal drug targets and biomarkers. Mass spectrometry-based analysis comparing proteomic profiles of CAFs and cancers characterized 9460 proteins of which 85 proteins had 16-fold higher expression in CAFs compared to cancer cells. Further interrogation of this rich resource could provide insight into the function of CAFs and could reveal putative stromal targets. We describe for the first time that heat shock protein β-6 (HSPB6/HSP20) and cyclooxygenase 1 (PTGS1/COX1) are overexpressed in CAFs compared to cancer cells.

Safety and anti-tumour activity of the IgE antibody MOv18 in patients with advanced solid tumours expressing folate receptor-alpha: a phase I trial

All antibodies approved for cancer therapy are monoclonal IgGs but the biology of IgE, supported by comparative preclinical data, offers the potential for enhanced effector cell potency. Here we report a Phase I dose escalation trial (NCT02546921) with the primary objective of exploring the safety and tolerability of MOv18 IgE, a chimeric first-in-class IgE antibody, in patients with tumours expressing the relevant antigen, folate receptor-alpha. The trial incorporated skin prick and basophil activation tests (BAT) to select patients at lowest risk of allergic toxicity. Secondary objectives were exploration of anti-tumour activity, recommended Phase II dose, and pharmacokinetics. Dose escalation ranged from 70 μg-12 mg. The most common toxicity of MOv18 IgE is transient urticaria. A single patient experienced anaphylaxis, likely explained by detection of circulating basophils at baseline that could be activated by MOv18 IgE. The BAT assay was used to avoid enrolling further patients with reactive basophils. The safety profile is tolerable and maximum tolerated dose has not been reached, with evidence of anti-tumour activity observed in a patient with ovarian cancer. These results demonstrate the potential of IgE therapy for cancer.

Clinical trial designs for evaluating and exploiting cancer evolution

The evolution of drug-resistant cell subpopulations causes cancer treatment failure. Current preclinical evidence shows that it is possible to model herding of clonal evolution and collateral sensitivity where an initial treatment could favourably influence the response to a subsequent one. Novel therapy strategies exploiting this understanding are being considered, and clinical trial designs for steering cancer evolution are needed. Furthermore, preclinical evidence suggests that different subsets of drug-sensitive and resistant clones could compete between themselves for nutrients/blood supply, and clones that populate a tumour do so at the expense of other clones. Treatment paradigms based on this clinical application of exploiting cell-cell competition include intermittent dosing regimens or cycling different treatments before progression. This will require clinical trial designs different from the conventional practice of evaluating responses to individual therapy regimens. Next-generation sequencing to assess clonal dynamics longitudinally will improve current radiological assessment of clinical response/resistance and be incorporated into trials exploiting evolution. Furthermore, if understood, clonal evolution can be used to therapeutic advantage, improving patient outcomes based on a new generation of clinical trials.

A Phase 1/2 trial of SRA737 (a Chk1 inhibitor) administered orally in patients with advanced cancer

BACKGROUND

This was a first-in-human Phase 1/2 open-label dose-escalation study of the novel checkpoint kinase 1 (Chk1) inhibitor SRA737.

METHODS

Patients with advanced solid tumours enrolled in dose-escalation cohorts and received SRA737 monotherapy orally on a continuous daily (QD) dosing schedule in 28-day cycles. Expansion cohorts included up to 20 patients with prospectively selected, pre-specified response predictive biomarkers.

RESULTS

In total, 107 patients were treated at dose levels from 20-1300 mg. The maximum tolerated dose (MTD) of SRA737 was 1000 mg QD, the recommended Phase 2 dose (RP2D) was 800 mg QD. Common toxicities of diarrhoea, nausea and vomiting were generally mild to moderate. Dose-limiting toxicity at daily doses of 1000 and 1300 mg QD SRA737 included gastrointestinal events, neutropenia and thrombocytopenia. Pharmacokinetic analysis at the 800 mg QD dose showed a mean Cmin of 312 ng/mL (546 nM), exceeding levels required to cause growth delay in xenograft models. No partial or complete responses were seen.

CONCLUSIONS

SRA737 was well tolerated at doses that achieved preclinically relevant drug concentrations but single agent activity did not warrant further development as monotherapy. Given its mechanism of action resulting in abrogating DNA damage repair, further clinical development of SRA737 should be as combination therapy.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov NCT02797964.

Efficacy and Safety of Weekly Paclitaxel Plus Vistusertib vs Paclitaxel Alone in Patients With Platinum-Resistant Ovarian High-Grade Serous Carcinoma: The OCTOPUS Multicenter, Phase 2, Randomized Clinical Trial

Importance

Patients with platinum-resistant or refractory ovarian high-grade serous carcinoma (PR-HGSC) have a poor prognosis and few therapeutic options. Preclinical studies support targeting PI3K/AKT/mTOR signaling in this setting, and a phase 1 study of the dual mTORC1/mTORC2 inhibitor vistusertib with weekly paclitaxel showed activity.

Objective

To evaluate whether the addition of vistusertib to weekly paclitaxel improves clinical outcomes in patients with PR-HGSC.

Design, Setting, and Participants

This phase 2, double-blind, placebo-controlled multicenter randomized clinical trial recruited patients from UK cancer centers between January 2016 and March 2018. Patients with PR-HGSC of ovarian, fallopian tube, or primary peritoneal origin and with measurable or evaluable disease (Response Evaluation Criteria in Solid Tumors version 1.1 and/or Gynecological Cancer Intergroup cancer antigen 125 criteria) were eligible. There were no restrictions on number of lines of prior therapy. Data analysis was performed from May 2019 to January 2022.

Interventions

Patients were randomized (1:1) to weekly paclitaxel (80 mg/m2 days 1, 8, and 15 of a 28-day cycle) plus oral vistusertib (50 mg twice daily) or placebo.

Main Outcomes and Measures

The primary end point was progression-free survival in the intention-to-treat population. Secondary end points included response rate, overall survival, and quality of life.

Results

A total of 140 patients (median [range] age, 63 [36-86] years; 17.9% with platinum-refractory disease; 53.6% with ≥3 prior therapies) were randomized. In the paclitaxel plus vistusertib vs paclitaxel plus placebo groups, there was no difference in progression-free survival (median, 4.5 vs 4.1 months; hazard ratio [HR], 0.84; 80% CI, 0.67-1.07; 1-sided P = .18), overall survival (median, 9.7 vs 11.1 months; HR, 1.21; 80% CI, 0.91-1.60) or response rate (odds ratio, 0.86; 80% CI, 0.55-1.36). Grade 3 to 4 adverse events were 41.2% (weekly paclitaxel plus vistusertib) vs 36.7% (weekly paclitaxel plus placebo), and there was no difference in quality of life.

Conclusions and Relevance

In this randomized clinical trial of weekly paclitaxel and dual mTORC1/2 inhibition in patients with PR-HGSC, vistusertib did not improve clinical activity of weekly paclitaxel.

Trial Registration

isrctn.org Identifier: ISRCTN16426935.

A Phase I Dose-escalation Study of AZD3965, an Oral Monocarboxylate Transporter 1 Inhibitor, in Patients with Advanced Cancer

PURPOSE

Inhibition of monocarboxylate transporter (MCT) 1-mediated lactate transport may have cytostatic and/or cytotoxic effects on tumor cells. We report results from the dose-escalation part of a first-in-human trial of AZD3965, a first-in-class MCT1 inhibitor, in advanced cancer.

PATIENTS AND METHODS

This multicentre, phase I, dose-escalation and dose-expansion trial enrolled patients with advanced solid tumors or lymphoma and no standard therapy options. Exclusion criteria included history of retinal and/or cardiac disease, due to MCT1 expression in the eye and heart. Patients received daily oral AZD3965 according to a 3+3 then rolling six design. Primary objectives were to assess safety and determine the MTD and/or recommended phase II dose (RP2D). Secondary objectives for dose escalation included measurement of pharmacokinetic and pharmacodynamic activity. Exploratory biomarkers included tumor expression of MCT1 and MCT4, functional imaging of biological impact, and metabolomics.

RESULTS

During dose escalation, 40 patients received AZD3965 at 5-30 mg once daily or 10 or 15 mg twice daily. Treatment-emergent adverse events were primarily grade 1 and/or 2, most commonly electroretinogram changes (retinopathy), fatigue, anorexia, and constipation. Seven patients receiving ≥20 mg daily experienced dose-limiting toxicities (DLT): grade 3 cardiac troponin rise (n = 1), asymptomatic ocular DLTs (n = 5), and grade 3 acidosis (n = 1). Plasma pharmacokinetics demonstrated attainment of target concentrations; pharmacodynamic measurements indicated on-target activity.

CONCLUSIONS

AZD3965 is tolerated at doses that produce target engagement. DLTs were on-target and primarily dose-dependent, asymptomatic, reversible ocular changes. An RP2D of 10 mg twice daily was established for use in dose expansion in cancers that generally express high MCT1/low MCT4).

Abstract 3461: Preclinical and clinical evaluation of the RAF/MEK clamp avutometinib (VS-6766) in combination with the mTOR inhibitor everolimus for the treatment of KRAS mutated non-small cell lung cancer

Background: KRAS mutations (mt) are found in ~30% of non-small cell lung cancers (NSCLC). Despite the approval and development of KRAS G12C and KRAS G12D inhibitors respectively, mechanisms of resistance to MAPK pathway inhibitors are emerging and combination strategies are needed for patients with KRAS mt NSCLC . Avutometinib (VS-6766) is a unique RAF/MEK clamp that inhibits MEK kinase activity and blocks RAF-mediated phosphorylation of MEK. We studied the preclinical and clinical activity of the combination of avutometinib with the mTOR inhibitor everolimus in KRAS mt NSCLC.

Methods: A panel of KRAS mt NSCLC cell lines were treated for 1 hour with clinically relevant concentrations of avutometinib and everolimus and changes in phosphoproteins were measured using an antibody array. We then tested for synergy of avutometinib and everolimus in 3D proliferation assays and in the H441 NSCLC xenograft model. A clinical trial is ongoing (NCT02407509) testing the combination of 3.2 mg avutometinib with 5 mg of everolimus administered twice weekly 3 weeks on/1 week off in 28-day cycles (previously defined as the recommended phase 2 dose) in a cohort of patients with KRAS mt NSCLC.

Results: Avutometinib inhibited the MAPK pathway (p-MEK, p-ERK, p-90RSK) with an increase in p-PRAS40, suggesting activation of the PI3K pathway as an adaptive resistance mechanism. Everolimus inhibited the PI3K pathway (p-p70S6K and p-RPS6). Among a panel of KRAS mt NSCLC cell lines, avutometinib + everolimus showed synergistic anti-proliferative activity across KRAS G12C, G12V and G12D variants (mean synergy score of ~18). In the H441 KRAS G12V NSCLC xenograft model, there was a significant reduction in tumor volume and increase in survival with the combination of avutometinib and everolimus (87% TGI; 66 days vs 36.5 days in control group) compared to control. In the clinical trial expansion, 16 patients with KRAS mt NSCLC have been treated so far with avutometinib and everolimus (5 G12V, 3 Q61H, 2 G12C, 2 G12A, 2 G12D, 1 G13A, 1 G13D; median prior lines = 2). The current objective response rate (ORR) among the 14 patients who have at least one post assessment scan is 3/14 (21%; 1 G12V, 1 G12A, 1 G13A) with 11/14 showing a reduction in tumor size as best response. The current progression free survival (PFS) is 5.3 months (95% CI 2.8-7.4 months) with 4 patients still on study. Updated data on the planned cohort size of 20 patients will be presented.

Conclusion: The combination of avutometinib and everolimus overcomes the activation of the PI3K/AKT/mTOR pathway which is an adaptive resistance mechanism to MAPK pathway inhibition. We have shown that avutometinib and everolimus induce synergistic anti-tumor effects preclinically, and preliminary data suggest clinically meaningful ORR and PFS in patients with KRAS mt NSCLC including non-G12C variants.

Citation Format: Simon Rodney, Adam R. Stewart, Victoria Sanchez Perez, Cienne Morton, Lisa A. Pickard, Taleen Shakouri, Toby Prout, Mona Parmar, Alison J. Turner, Silvia Coma, Jonathan Pachter, Laura Finneran, Emma Hall, James Spicer, Anna Minchom, Udai Banerji. Preclinical and clinical evaluation of the RAF/MEK clamp avutometinib (VS-6766) in combination with the mTOR inhibitor everolimus for the treatment of KRAS mutated non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3461.

A Phase I/II Trial of Oral SRA737 (a Chk1 Inhibitor) Given in Combination with Low-Dose Gemcitabine in Patients with Advanced Cancer

PURPOSE

This was a Phase I/II trial of the novel checkpoint kinase 1 (Chk1) inhibitor SRA737 given in combination with gemcitabine. Its objectives were to establish the safety profile, recommended Phase 2 dose (RP2D), pharmacokinetics profile, and clinical activity of SRA737.

PATIENTS AND METHODS

Patients with advanced solid tumors were enrolled into dose-escalation cohorts and treated in 28-day cycles with oral SRA737 on days 2, 3, 9, 10, 16, and 17, and intravenous gemcitabine on days 1, 8, and 15. Treatment was continued until progression. Each expansion cohort included up to 20 patients with specific genetically defined tumors.

RESULTS

The RP2D was determined to be 500 mg SRA737 combined with low-dose (250 mg/m2) gemcitabine. Of 143 enrolled patients, 77 were treated at doses of at least 500 mg SRA737 combined with 250 mg/m2 gemcitabine. Common toxicities of nausea, vomiting, fatigue, and diarrhea were primarily mild to moderate, and rarely led to treatment discontinuation. Anemia, neutropenia, and thrombocytopenia were grade ≥3 in 11.7%, 16.7%, and 10% of patients treated at the RP2D, respectively. The objective response rate (ORR) was 10.8% overall and notably the ORR in anogenital cancer was 25%. Partial tumor responses were observed in anogenital cancer, cervical cancer, high-grade serous ovarian cancer, rectal cancer, and small cell lung cancer.

CONCLUSIONS

SRA737 in combination with low-dose gemcitabine was well tolerated with lower myelotoxicity than has been seen at standard doses of gemcitabine or with other combinations of Chk1 inhibitors with gemcitabine. Tumor responses were observed in anogenital and other solid tumors.

A Phase I Trial of CT900, a Novel α-Folate Receptor-Mediated Thymidylate Synthase Inhibitor, in Patients with Solid Tumors with Expansion Cohorts in Patients with High-Grade Serous Ovarian Cancer

PURPOSE

CT900 is a novel small molecule thymidylate synthase inhibitor that binds to α-folate receptor (α-FR) and thus is selectively taken up by α-FR-overexpressing tumors.

PATIENTS AND METHODS

A 3+3 dose escalation design was used. During dose escalation, CT900 doses of 1-6 mg/m2 weekly and 2-12 mg/m2 every 2 weeks (q2Wk) intravenously were evaluated. Patients with high-grade serous ovarian cancer were enrolled in the expansion cohorts.

RESULTS

109 patients were enrolled: 42 patients in the dose escalation and 67 patients in the expansion cohorts. At the dose/schedule of 12 mg/m2/q2Wk (with and without dexamethasone, n = 40), the most common treatment-related adverse events were fatigue, nausea, diarrhea, cough, anemia, and pneumonitis, which were predominantly grade 1 and grade 2. Levels of CT900 more than 600 nmol/L needed for growth inhibition in preclinical models were achieved for >65 hours at a dose of 12 mg/m2. In the expansion cohorts, the overall response rate (ORR), was 14/64 (21.9%). Thirty-eight response-evaluable patients in the expansion cohorts receiving 12 mg/m2/q2Wk had tumor evaluable for quantification of α-FR. Patients with high or medium expression had an objective response rate of 9/25 (36%) compared with 1/13 (7.7%) in patients with negative/very low or low expression of α-FR.

CONCLUSIONS

The dose of 12 mg/m2/q2Wk was declared the recommended phase II dose/schedule. At this dose/schedule, CT900 exhibited an acceptable side effect profile with clinical benefit in patients with high/medium α-FR expression and warrants further investigation.

CONSENT - A Randomised Controlled Trial of Enhanced Informed Consent Compared to Standard Informed Consent to Improve Patient Understanding of Early Phase Oncology Clinical Trials – GBM Cohort (Nonrandomised) Analysis

AIMS

Early phase cancer clinical trials have become more complicated and patients often misunderstand their nature and purpose. CONSENT (NCT04407676) is a randomised controlled trial testing whether enhanced informed consent for patient education can improve comprehension – since patients with glioblastoma multiforme (GBM) have a higher rate of baseline cognitive impairment, we studied this group separately.

METHOD

GBM patients (from the ICE-CAP Phase 1 study - NCT03673787), underwent the schedule for the standard CONSENT arm - full length trial PIS, Quality of Informed Consent Questionnaire Parts A and B (QuIC-A and QuIC-B), experimental intervention (2 page study aid and 10 educational videos), and a repeat QuIC-A and QuIC-B. The primary endpoint for this subgroup was the difference in QuIC-A scores before and after the intervention using a paired t-test.

RESULTS

6 patients with GBM were recruited - 3 did not complete any study questionnaires. The three pre intervention QuIC-A scores were 70, 81, 88, with a mean of 75 (unit reference 76). The three pre intervention QuIC-B scores were 69, 62, 75 with a mean of 69 (unit reference is 91). Only one patient completed the post intervention questionnaire - their QuIC-A score moved from 88 to 100.

CONCLUSION

This study demonstrates the significant difficulties in studying comprehension in patients with GBM considering early phase trials. There is a need for creative multi-modality solutions to provide information to GBM patients considering clinical trials, and novel tools to assess the effectiveness of these solutions.

Abstract 3476: Mechanistic evaluation of VS-6766 (dual RAF/MEK inhibitor) and defactinib (FAK inhibitor) in low-grade serous ovarian cancer models with correlations to clinical response

Background: Low-grade serous ovarian cancer (LGSOC) constitutes up to 10% of all ovarian cancer and has clinical and molecular characteristics (resistance to chemotherapy, presence of RAS/RAF mutations, lack of TP53 mutations) distinct from high-grade serous ovarian cancer. Here, we characterized the effects of the dual RAF/MEK inhibitor VS-6766 and the FAK inhibitor defactinib on signal transduction and viability in LGSOC cell lines and patient-derived organoids. To correlate molecular characteristics with clinical response, we characterized genomic alterations in archival tumor samples from patients with LGSOC treated with the combination of VS-6766 and defactinib on a clinical trial (FRAME).

Material and Methods: We exposed 5 LGSOC cell lines to clinical Cmax concentrations adjusted for protein binding of VS-6766 and defactinib. We quantified phospho- and total proteins (n=66) with an antibody-bead based assay normalized to GAPDH. We also studied growth inhibitory effects of the combination on KRAS mutant (mt) LGSOC patient-derived organoids. We performed next generation sequencing on archival samples from LGSOC patients treated with VS-6766 in combination with defactinib.

Results: Signal transduction changes at 1 hr included reduction of p-FAK in 5/5 cell lines in response to defactinib. Cells exposed to VS-6766 showed a reduction in p-ERK and p-p90-RSK in 4/5 cell lines. Additionally, VS-6766 decreased p-cJUN and increased p-IκB in 4/5 cell lines, changes correlated with apoptosis. At 24 hrs, p-ERK and p-p90-RSK inhibition were maintained in 3/5 cell lines. Both drugs increased cleaved PARP in 4/5 cell lines and VS-6766 increased p-SMAD3 and BIM levels, indicating an increase in cell death/apoptosis. The combination of VS-6766 + defactinib showed synergistic growth inhibition in a KRAS mt LGSOC organoid model (combination index 0.51). The clinical combination of VS-6766 and defactinib (September 2021 cut-off) has shown an objective response rate (ORR) of 11/24 (46%) across all patients with LGSOC, and an ORR of 64% (7/11) for patients with KRAS mt LGSOC (n=11). In addition to mutations in KRAS, emerging data may suggest a correlation of U2AF1 and MED12 mutations with response.

Conclusions: VS-6766, the dual RAF/MEK inhibitor, induces significant inhibition of ERK pathway signaling in addition to perturbations in TNF/NFκB signaling. Both defactinib and VS-6766 induce apoptosis in LGSOC models. The results provide mechanistic insights into the encouraging response rates observed in patients with LGSOC treated with VS-6766 and defactinib (NCT03875820). These data support the ongoing randomized phase II ENGOTov60/GOG3052/RAMP201 study (NCT04625270).

Citation Format: Adam R. Stewart, Lisa Pickard, Ekta Paranjape, Victoria Sanchez Perez, Sanjib Chowdhury, Stephanie Lustgarten, Silvia Coma, Jonathan A. Pachter, Mark S. Carey, Gabriel DiMattia, Hannah C. Badham, Toby Prout, Mona Parmar, Muneeb Mahmud, Christina Yap, Matthew G. Krebs, Susana Banerjee, Udai Banerji. Mechanistic evaluation of VS-6766 (dual RAF/MEK inhibitor) and defactinib (FAK inhibitor) in low-grade serous ovarian cancer models with correlations to clinical response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3476.

Abstract 3187: Understanding the role of cancer-associated fibroblasts (CAFs) on pathogenesis of KRAS mutated cancers by defining differences in the basal state proteome and secretome

Background: KRAS is commonly mutated in solid tumors. Cancer-associated fibroblasts (CAFs) are a key tumor stroma component, which can affect cancer progression and drug response. We hypothesized that defining the differential secreted proteins between CAFs and KRAS mutant-cancer cells could reveal potential mechanisms by which CAFs influence cancer progression and drug resistance.

Methods: We studied 12 cell lines: 3 KRAS mutant-colorectal cancer cell lines (H747, LIM2099 and SW620), 3 KRAS mutant-lung cancer cell lines (H1792, H2030 and H23), 3 KRAS mutant-pancreatic cancer cell lines (CAPAN1, DANG, MIAPACA2) and 3 CAF cell line models (colorectal and lung CAF and pancreatic stellate cells). We quantified proteins in cell lines and serum-free media after 24 hour incubation in cells using mass spectrometry in a multiplexed manner (12plex) in triplicates to characterize the proteome and the profile of secreted proteins (secretome), respectively. Prediction software (signalP, secretomeP, TMHMM) and databases (surfaceome and cell surface protein atlas) were used to annotate secreted or transmembrane proteins.

Results: Our proteome analysis quantified 9307 proteins. T-test between the cell types (CAF vs cancer) identified 1770 differentially expressed proteins, where 712 proteins were CAF-enriched. This included known CAF markers (e.g α smooth muscle actin) but also proteins not known to be CAF markers such as heat shock protein beta-5/6 (HSPB5/6). The secretome analysis identified 2330 secreted or transmembrane proteins where 202 were differentially expressed between cancer cells and CAFs. 190 proteins were CAF-enriched with the highest ranking being syndecan-2 (SDC2), collagen α-28(I) chain (COL28A1), decorin (DCN) and wnt family member 5B (WNT5B). Interestingly, basal proteome analysis of KRAS mutant-cancer cells showed expression of receptors corresponding to the CAF-enriched ligands, such as receptor tyrosine kinase-like orphan receptor 1/2 (ROR1/2) which respond to WNT5B. This suggests that CAF-enriched ligands may activate certain downstream pathways, including non-canonical WNT signaling, in KRAS mutant-cancer cells.

Conclusion: We undertook deep quantitative proteomics where we identified potential novel CAF markers HSPB5/6. We have also found proteins in the CAF secretome, such as WNT5B, which may drive drug resistance in KRAS mutant-cancer cells.

Citation Format: Rachel Lau, Lu Yu, Theodoros Roumeliotis, Lisa Pickard, Adam Stewart, Jyoti Choudhary, Udai Banerji. Understanding the role of cancer-associated fibroblasts (CAFs) on pathogenesis of KRAS mutated cancers by defining differences in the basal state proteome and secretome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3187.

Phase 1, dose-escalation study of guadecitabine (SGI-110) in combination with pembrolizumab in patients with solid tumors

Background

Data suggest that immunomodulation induced by DNA hypomethylating agents can sensitize tumors to immune checkpoint inhibitors. We conducted a phase 1 dose-escalation trial (NCT02998567) of guadecitabine and pembrolizumab in patients with advanced solid tumors. We hypothesized that guadecitabine will overcome pembrolizumab resistance.

Methods

Patients received guadecitabine (45 mg/m² or 30 mg/m², administered subcutaneously on days 1–4), with pembrolizumab (200 mg administered intravenously starting from cycle 2 onwards) every 3 weeks. Primary endpoints were safety, tolerability and maximum tolerated dose; secondary and exploratory endpoints included objective response rate (ORR), changes in methylome, transcriptome, immune contextures in pre-treatment and on-treatment tumor biopsies.

Results

Between January 2017 and January 2020, 34 patients were enrolled. The recommended phase II dose was guadecitabine 30 mg/m², days 1–4, and pembrolizumab 200 mg on day 1 every 3 weeks. Two dose-limiting toxicities (neutropenia, febrile neutropenia) were reported at guadecitabine 45 mg/m² with none reported at guadecitabine 30 mg/m². The most common treatment-related adverse events (TRAEs) were neutropenia (58.8%), fatigue (17.6%), febrile neutropenia (11.8%) and nausea (11.8%). Common, grade 3+ TRAEs were neutropaenia (38.2%) and febrile neutropaenia (11.8%). There were no treatment-related deaths. Overall, 30 patients were evaluable for antitumor activity; ORR was 7% with 37% achieving disease control (progression-free survival) for ≥24 weeks. Of 12 evaluable patients with non-small cell lung cancer, 10 had been previously treated with immune checkpoint inhibitors with 5 (42%) having disease control ≥24 weeks (clinical benefit). Reduction in LINE-1 DNA methylation following treatment in blood (peripheral blood mononuclear cells) and tissue samples was demonstrated and methylation at transcriptional start site and 5’ untranslated region gene regions showed enriched negative correlation with gene expression. Increases in intra-tumoural effector T-cells were seen in some responding patients. Patients having clinical benefit had high baseline inflammatory signature on RNAseq analyses.

Conclusions

Guadecitabine in combination with pembrolizumab is tolerable with biological and anticancer activity. Reversal of previous resistance to immune checkpoint inhibitors is demonstrated.

Individualized Prediction of Drug Response and Rational Combination Therapy in NSCLC Using Artificial Intelligence-Enabled Studies of Acute Phosphoproteomic Changes

We hypothesize that the study of acute protein perturbation in signal transduction by targeted anticancer drugs can predict drug sensitivity of these agents used as single agents and rational combination therapy. We assayed dynamic changes in 52 phosphoproteins caused by an acute exposure (1 hour) to clinically relevant concentrations of seven targeted anticancer drugs in 35 non-small cell lung cancer (NSCLC) cell lines and 16 samples of NSCLC cells isolated from pleural effusions. We studied drug sensitivities across 35 cell lines and synergy of combinations of all drugs in six cell lines (252 combinations). We developed orthogonal machine-learning approaches to predict drug response and rational combination therapy. Our methods predicted the most and least sensitive quartiles of drug sensitivity with an AUC of 0.79 and 0.78, respectively, whereas predictions based on mutations in three genes commonly known to predict response to the drug studied, for example, EGFR, PIK3CA, and KRAS, did not predict sensitivity (AUC of 0.5 across all quartiles). The machine-learning predictions of combinations that were compared with experimentally generated data showed a bias to the highest quartile of Bliss synergy scores (P = 0.0243). We confirmed feasibility of running such assays on 16 patient samples of freshly isolated NSCLC cells from pleural effusions. We have provided proof of concept for novel methods of using acute ex vivo exposure of cancer cells to targeted anticancer drugs to predict response as single agents or combinations. These approaches could complement current approaches using gene mutations/amplifications/rearrangements as biomarkers and demonstrate the utility of proteomics data to inform treatment selection in the clinic.

Phase I trial of the RAF/MEK clamp VS-6766 in combination with everolimus using an intermittent schedule with expansion in NSCLC across multiple KRAS variants

9018

Background: VS-6766 is a small molecule RAF/MEK clamp that results in the reduction of p-MEK and p-ERK. Preclinical data show synergy of VS-6766 with the mTOR inhibitor everolimus across a panel of KRAS mutated (mt) NSCLC cell lines. This clinical trial evaluated the safety and efficacy of a novel intermittent regimen of VS-6766 and everolimus with an expansion in KRAS mt NSCLC (NCT02407509). Methods: The trial used a 3+3 dose escalation design with an intermittent once a week schedule A, and if tolerated, twice a week schedule B (Mon-Thu or Tue-Fri) for both drugs on a 3 weeks on/1 week off, 28 day cycle. Patients with RAS or RAF mt cancers were eligible for the dose escalation cohort, and 20 patients with KRAS mt NSCLC will be treated in the dose expansion cohort. Toxicity was evaluated by NCI CTC V4 and efficacy was evaluated using RECIST 1.1. Results: A total of 28 patients have been treated; median age 60 yrs (range 36-78), and median lines of previous treatment 3 (range 0-7). Sixteen patients have been treated in the dose escalation (3 in schedule A and 13 in the schedule B). The doses of 4 mg of VS-6766 and 5 mg everolimus (once weekly) were tolerated with no dose limiting toxicities (DLTs) and the dose intensity escalated to schedule B (twice weekly). At 4 mg VS-6766 twice weekly, DLTs were observed in two out of six patients and included grade 4 CPK elevation and grade 3 rash. Thus, the dose in schedule B (twice weekly) was de-escalated to 3.2 mg VS-6766 and the dose of everolimus was kept at 5 mg. No DLTs were reported in 6 patients and thus this was declared as the recommended phase 2 dose (RP2D). At the RP2D, the grade 3-4 drug related AE were rash (18%) and pruritus (7%). In the dose escalation cohorts, 3 partial responses (PRs) were reported (2 KRAS G12D low grade serous ovarian cancer and 1 NRAS Q61K mt thyroid cancer). In the KRAS mt NSCLC expansion cohort, 10 patients are evaluable for efficacy and 2 confirmed responses were reported ( KRAS mutations G12V and G13A) with an objective response rate (ORR) 20% to date. The disease control rate (PR + SD) at the first scheduled evaluation was 90%. The median progression free survival (PFS) in the KRAS mt NSCLC cohort is 6.35 months (95% CI 3.52 – not reached). Updated ORR and PFS data will be presented. Conclusions: A tolerable intermittent dosing schedule targeting both the MAPK and PI3K pathways has been established. The combination of VS-6766 with everolimus has shown activity in patients with a variety of KRAS mutation variants including responses in KRAS mt NSCLC.

A multi-modular phase I/II study of UCB6114, a first-in-class, fully human IgG4P anti-Gremlin-1 monoclonal antibody, as monotherapy and in combination with mFOLFOX6 or trifluridine/tipiracil, for patients with advanced gastrointestinal (GI) tumors

TPS221

Background: Despite recent advances, effective treatment for GI cancers remains a significant unmet medical need. Gremlin-1 is secreted by the peri-tumoral stroma and down-regulates bone morphogenetic proteins (BMP) -2, -4, and -7 (members of the transforming growth factor-β superfamily), thereby allowing malignant cell expansion, renewal, and a more treatment-resistant mesenchymal phenotype. Gremlin-1 mRNA is highly expressed in multiple solid tumors including >60% of colorectal, pancreatic and esophageal cancers. UCB6114 is a first-in-class, fully human IgG4P monoclonal antibody optimized for neutralizing the activity of human Gremlin-1 thereby restoring BMP signaling. Preclinical studies have demonstrated that UCB6114 binds to Gremlin-1, inhibits its pharmacological activity, and has antitumor activity in several in vivo mouse models (including several GI cancers). Methods: ONC001 (clinicaltrials.gov: NCT04393298) is an ongoing multi-part, multicenter, nonrandomized, open-label, Phase I/II study evaluating the safety, pharmacokinetics (PK) and antitumor activity of UCB6114 administered intravenously as monotherapy or in combination with selected standard of care (SOC) regimens. Eligible patients (pts) are: aged ≥18 years; resistant or refractory to standard therapy; ECOG performance status 0/1; and have adequate renal, hepatic and bone marrow function. In the Phase I monotherapy dose escalation and adaption part (part A and A1; modified rolling 6 design), up to 66 pts with advanced solid tumors associated with high levels of Gremlin-1 mRNA expression will be recruited. In parts B and C (modified toxicity probability interval design), up to 54 pts with locally advanced or metastatic colorectal, gastric or gastroesophageal junction adenocarcinomas will receive UCB6114 in escalating doses in combination with either mFOLFOX6 (5-fluorouracil, leucovorin and oxaliplatin) or trifluridine/tipiracil, given at SOC dosing and schedules. The overarching objective of the phase I parts of the study (Parts A‒C) is to identify the recommended phase II dose of UCB6114 either as monotherapy or in combination. The primary objective is to characterize the safety profile of UCB6114; secondary and exploratory objectives include PK, antitumor activity (RECIST v1.1), and pharmacodynamics (including circulating Gremlin-1). Enrollment in ONC001 began in July 2020; as of Sept 2021, four dose escalation levels in the monotherapy dose-escalation module (Part A) have been completed without DLT. Recruitment to parts B and C is due to commence in Q4 2021. Clinical trial information: NCT04393298.

Abstract P036: Trial in progress: Combination of the dual RAF/MEK inhibitor VS-6766 with the mTOR inhibitor everolimus with expansion in patients with KRAS mutant NSCLC

The RAS/RAF/MEK/ERK (MAPK) pathway is a frequently deregulated oncogenic pathway in cancer driven by RAS and RAF mutations as well as being a key signaling pathway downstream of deregulated receptor tyrosine kinases. Although RAF and MEK have been validated as anticancer targets and several BRAF and MEK inhibitors are FDA approved, acquired resistance develops in most patients. Preclinically, inhibition of RAF or MEK has been found to activate AKT/mTOR signaling as a potential resistance mechanism, and combination of MEK inhibition with an inhibitor of the AKT/mTOR pathway yields improved anti-tumor activity. However, combined inhibition of MEK with an AKT or mTOR inhibitor has typically shown poor clinical tolerability. VS-6766 is a unique dual RAF/MEK inhibitor which blocks MEK activity without the compensatory MEK activation that limits the efficacy of other MEK inhibitors. VS-6766 has shown clinical responses as a single agent in gynecological cancers and KRAS mutant non-small cell lung cancer (NSCLC) (Guo Lancet Oncology 2020), and has shown clinical responses in combination with the focal adhesion kinase (FAK) inhibitor defactinib in patients with low-grade serous ovarian cancer and KRAS mutated NSCLC. To explore the combination of VS-6766 with blockade of the AKT/mTOR pathway, we tested the combination of VS-6766 with the mTOR inhibitor everolimus for potential synergy across a variety of RAS pathway mutations and tumor types in preclinical experiments. In 3D proliferation assays in vitro, VS-6766 was synergistic with everolimus in reducing viability of cell lines representing multiple MAPK pathway alterations, including KRAS (G12C, G12D, G12V and G13D), BRAF V600E, NRAS and NF1 mutations. Synergy of VS-6766 with everolimus was observed in 8/9 NSCLC, 16/20 colorectal cancer, 7/10 melanoma and 5/7 pancreatic cancer cell lines tested. These preclinical data support testing the combination of VS-6766 with everolimus in patients with KRAS mutant NSCLC as well as in numerous other cancer indications with various MAPK pathway alterations. A phase I study is ongoing to assess the combination of VS-6766 with everolimus with an intermittent dosing schedule. The clinical trial uses a rule-based design of 3+3 dose escalation cohorts, initially with once weekly dosing of VS-6766 in combination with everolimus. If this was found to be tolerable, the combination of twice weekly dosing of both compounds was to be explored. Following establishment of the recommended phase 2 dose (RP2D) for the combination, an expansion cohort (n = 10) in patients with KRAS mutant NSCLC was planned. The trial is currently recruiting into an expansion cohort of patients with KRAS mutated NSCLC ;NCT02407509, (Trial in Progress).

Citation Format: Thubeena Manickavasagar, Chara Stavraka, Kaiser Anam, Silvia Coma, Sanjib Chowdhury, Jonathan A. Pachter, Tom Parker, Mona Parmar, Laura Finneran, Emma Hall, James Spicer, Anna Minchom, Udai Banerji. Trial in progress: Combination of the dual RAF/MEK inhibitor VS-6766 with the mTOR inhibitor everolimus with expansion in patients with KRAS mutant NSCLC [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P036.

A Wolf in Sheep's Clothing: Systemic Immune Activation Post Immunotherapy

Introduction

Immune checkpoint inhibitors (ICIs) are increasingly a standard of care for many cancers; these agents can result in immune-related adverse events (irAEs) including fever, which is common but can rarely be associated with systemic immune activation (SIA or acquired HLH).

Methods

All consecutive patients receiving ICIs in the Drug Development Unit of the Royal Marsden Hospital between May 2014 and November 2019 were retrospectively reviewed. Patients with fever ≥ 38°C or chills/rigors (without fever) ≤ 6 weeks of commencing ICIs were identified for clinical data collection.

Results

Three patients met diagnostic criteria for SIA/HLH with median time to onset of symptoms of 10 days. We describe the clinical evolution, treatment used, and outcomes for these patients. High-dose steroids are used first-line with other treatments, such as tocilizumab, immunoglobulin and therapeutic plasmapheresis can be considered for steroid-refractory SIA/HLH.

Conclusion

SIA/HLH post ICI is a rare but a potentially fatal irAE that presents with fever and a constellation of nonspecific symptoms. Early recognition and timely treatment are key to improving outcomes.

Preliminary evidence of antitumour activity of Ipatasertib (Ipat) and Atezolizumab (ATZ) in glioblastoma patients (pts) with PTEN loss from the Phase 1 Ice-CAP trial (NCT03673787)

Aims

Despite improved understanding of effector T-cell trafficking into the central nervous system, initial trials with anti-PD1/PD-L1 immune checkpoint inhibitors (ICIs) have failed to meet their primary endpoints. PTEN loss of function is frequent in GBM and has been correlated with not only poor overall prognosis, but also impaired antitumour responses, including reduced T cell infiltration into tumour and reduced efficacy of ICIs.

Ipatasertib is a novel, potent, selective, small-molecule inhibitor of Akt. We have shown that Ipatasertib efficiently depletes FOXP3+ regulatory T cells from the tumour microenvironment (TME) resulting in increased infiltration of effector T cells in solid tumours (Lopez 2020, AACR).

We hypothesize that the use of AKT inhibition in PTEN glioblastomas may deplete the TME of suppressive immune cells, and render malignant brain tumours more responsive to ICIs. We present updated data for the combination of Ipat+ATZ in patients with glioblastoma.

Method

Patients with relapsed WHO grade IV GBM with stable neurological symptoms ≥5 days prior to enrolment, requiring <3mg Dexamethasone were recruited into two cohorts of this early phase, open-label, single-centre trial studying the combination of Ipatasertib (Ipat) and Atezolizumab (ATZ): a dose finding cohort (A2; n=9) and an expansion cohort (B3; n=7, recruitment ongoing).

The Ice-CAP A2 cohort assessed safety, pharmacodynamic, and preliminary clinical activity of Ipat (200mg or 400mg OD) + ATZ (1200mg Q3W) in pts with potentially resectable relapsed WHO Grade IV GBM. Pts had a 14-21-day run-in phase of Ipat then surgical tumour resection. Combination Ipat+ATZ commenced post surgery. Patients who declined surgery or who were deemed high risk for surgery proceeded directly to combination.

Patients in the expansion cohort B3 commenced directly on Ipat+ATZ at the RP2D of 400mg Ipat with ATZ.

Results

16 evaluable recurrent GBM pts were enrolled across two cohorts. Median age 56 yrs (25-71 yrs). Median ECOG PS 1. Median lines of prior therapy 1 (range 1-4). 10 pts had PTEN loss by IHC (H<30) and/or PTEN mutations on next generation sequencing.

No DLTs, treatment-related (TR) serious adverse events (AEs), or immune-related AEs were observed. Most common TR AEs were G1 diarrhoea (44%), mucositis (17%), rash (28%).

Clinical benefit rate (CR, PR and SD> 6 cycles) at clinical cutoff date (23/02/21) in patients with PTEN aberration was 30% (3/10). A 58-year-old man with PTEN loss had MRI at Cycle 5 showing worsening enhancement suggestive of disease progression. Resection of the lesion showed intense lymphocyte infiltration and pathological CR. He is currently on Cycle 22 with no evidence of disease. Two other patients with PTEN loss with radiological stable disease per RANO criteria remain well on study for >6 cycles.

Conclusion

Combination Ipat+ATZ appears safe and tolerable in GBM pts, with 400mg Ipatasertib OD + 1200mg ATZ Q3W declared as RP2D. Early efficacy signals were detected with PTEN loss being a promising predictive biomarker for response to combination. An expansion cohort enriched with pts with PTEN loss is ongoing.

A phospho-proteomic study of cetuximab resistance in KRAS/NRAS/BRAFV600 wild-type colorectal cancer

PURPOSE

We hypothesised that plasticity in signal transduction may be a mechanism of drug resistance and tested this hypothesis in the setting of cetuximab resistance in patients with KRAS/NRAS/BRAFV600 wild-type colorectal cancer (CRC).

METHODS

A multiplex antibody-based platform was used to study simultaneous changes in signal transduction of 55 phospho-proteins in 12 KRAS/NRAS/BRAFV600 wild-type CRC cell lines (6 cetuximab sensitive versus 6 cetuximab resistant) following 1 and 4 h in vitro cetuximab exposure. We validated our results in CRC patient samples (n = 4) using ex vivo exposure to cetuximab in KRAS/NRAS/BRAFV600 cells that were immunomagnetically separated from the serous effusions of patients with known cetuximab resistance.

RESULTS

Differences in levels of phospho-proteins in cetuximab sensitive and resistant cell lines included reductions in phospho-RPS6 and phospho-PRAS40 in cetuximab sensitive, but not cetuximab resistant cell lines at 1 and 4 h, respectively. In addition, phospho-AKT levels were found to be elevated in 3/4 patient samples following ex vivo incubation with cetuximab for 1 h. We further explored these findings by studying the effects of combinations of cetuximab and two PI3K pathway inhibitors in 3 cetuximab resistant cell lines. The addition of PI3K pathway inhibitors to cetuximab led to a significantly higher reduction in colony formation capacity compared to cetuximab alone.

CONCLUSION

Our findings suggest activation of the PI3K pathway as a mechanism of cetuximab resistance in KRAS/NRAS/BRAFV600 wild-type CRC.

Study protocol for a randomised controlled trial of enhanced informed consent compared to standard informed consent to improve patient understanding of early phase oncology clinical trials (CONSENT)

INTRODUCTION

Early phase cancer clinical trials have become increasingly complicated in terms of patient selection and trial procedures-this is reflected in the increasing length of participant information sheets (PIS). Informed consent for early phase clinical trials has been contentious due to the potential ethical issues associated with performing experimental research on a terminally ill population which has exhausted standard treatment options. Empirical studies have demonstrated significant gaps in patient understanding regarding the nature and intent of these trials. This study aims to test whether enhanced informed consent for patient education can improve patient scores on a validated questionnaire testing clinical trial comprehension.

METHODS AND ANALYSIS

This is a randomised controlled trial that will allocate patients who are eligible to participate in one of four investigator-initiated clinical trials at the Royal Marsden Drug Development Unit to either a standard arm or an experimental arm, stratified by age and educational level. The standard arm will involve the full length trial PIS, followed by electronic or paper administration of the Quality of Informed Consent Questionnaire Parts A and B (QuIC-A and QuIC-B). The experimental arm will involve the full length trial PIS, exposure to a two-page study aid and 10 online educational videos, followed by administration of the QuIC-A and QuIC-B. The primary endpoint will be the difference (using a one-sided two-sample t-test) in the QuIC-A score, which measures objective understanding, between the standard and experimental arm. Accrual target is at least 17 patients per arm to detect an 8 point difference (80% power, alpha 0.05).

ETHICS AND DISSEMINATION

Ethics approval was granted by the National Health Service Health Research Authority on 15 June 2020-IRAS Project ID 277065, Protocol Number CCR5165, REC Reference 20/EE/0155. Results will be disseminated via publication in a relevant journal.

TRIAL REGISTRATION NUMBER

NCT04407676; Pre-results.

Abstract CT019: A phase I trial of the combination of the dual RAF-MEK inhibitor VS-6766 and the FAK inhibitor defactinib: Evaluation of efficacy in KRAS mutated NSCLC

Background

KRAS is a known oncogenic driver in non-small cell lung cancer (NSCLC), with KRAS G12C and G12V mutations occurring in ~13% and ~7% of the of NSCLC ( adenocarcinoma subtype). The dual RAF-MEK inhibitor VS-6766 has shown single agent activity against G12V KRAS mutated NSCLC (Guo C et al Lancet Oncology 2020, 21:1478-88). Based on pre-clinical data, we hypothesised that augmented focal adhesion kinase (FAK) signalling is a mechanism of resistance to MEK inhibition and devised the current clinical trial. We have previously reported the safety of an intermittent schedule of the combination of VS-6766 and the FAK inhibitor defactinib and its efficacy in low grade serous ovarian cancer (Shinde et al., AACR 2020). We now report the activity of the combination in KRAS mutated NSCLC.

Methods

Patients were treated with an intermittent dose of drugs VS-6766 at 3.2 - 4 mg twice a week and defactinib 200 mg twice daily in the dose escalation and expansion cohorts of the study. Both drugs were administered three weeks on/one week off in 28-day cycles. We aim to recruit 20 patients with KRAS mutated NSCLC in an expansion cohort.

Results

To date, 19 patients with KRAS mutated NSCLC have been treated in the dose escalation and expansion cohorts. All patients had been previously treatment with a PD-1 or PDL-1 targeting immune checkpoint inhibitor. The median age was 64 years (22 - 73), M/F ratio was 7/12, and the median prior lines of treatment was 3. Currently, 17 of 19 patients have had at least one re-staging assessment, 2/17 (12%) patients had a partial response and 10/17 (59%) had stable disease as their best response. Of note, 11/17 (65%) patients had a degree of reduction in size of their tumours and 5/17 (29%) have been treated for 6 months or more with 3 patients still on treatment. Interestingly, 2/2 (100%) of the KRAS G12V NSCLC patients showed a partial response.

Conclusions

Developing new treatments for non-G12C KRAS mutated NSCLC is an area of unmet need. The combination of VS-6766 and defactinib treatment in cohorts of patients with NSCLC pre-treated with chemotherapy and immunotherapy has shown anti-tumour activity in subsets of patients with KRAS mutated NSCLC, in particular those with tumours harbouring KRAS G12V mutations. A registration-directed study evaluating VS-6766 ± defactinib for treatment of recurrent NSCLC with KRAS G12V mutation (NCT04620330) has been initiated

Citation Format: Matthew G. Krebs, Rajiv Shinde, Rozana Abdul Rahman, Rafael Grochot, Martin Little, Jenny King, Joseph Kitchin, Mona Parmar, Alison Turner, Muneeb Mahmud, Christina Yap, Nina Tunariu, Juanita Lopez, Johann S. De Bono, Udai Banerji, Anna Minchom. A phase I trial of the combination of the dual RAF-MEK inhibitor VS-6766 and the FAK inhibitor defactinib: Evaluation of efficacy in KRAS mutated NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT019.

Abstract CT120: Results of the glioblastoma multiforme (GBM) cohort of phase 1 trial Ice-CAP (NCT03673787): Preliminary evidence of antitumour activity of Ipatasertib (Ipa) and Atezolizumab (A) in patients (pts) with PTEN loss

Background: Hyperactivation of the PI3K/AKT pathway correlates with impaired antitumour response, including reduced T cell infiltration into tumour and reduced efficacy of immune checkpoint inhibitors (ICIs). PTEN loss of function, often observed in GBM, may contribute to refractoriness of ICIs in this disease. Methods: The Ice-CAP A2 cohort assessed safety, pharmacodynamic, and preliminary clinical activity of Ipa (200mg or 400mg OD) + A (1200mg Q3W) in pts with potentially resectable relapsed WHO Grade IV GBM. Key inclusion criteria were stable neurological symptoms ≥5 days prior to enrolment, steroid requirement <3mg Dexamethasone. Pts had a 14-21-day run-in phase of Ipa then surgical tumour resection. Combination Ipa+A commenced post surgery. Dose-limiting toxicity (DLT) period included run-in phase to Cycle 1 completion (≤11 wks). Results: 10 evaluable pts were enrolled (3 had Ipa at 200mg, 7 at 400mg); median age 58 (range 25-70y), ECOG score 1; median duration of treatment 8 wks. 2 remain on treatment. No DLTs, treatment-related (TR) serious adverse events (AEs), or immune-related AEs were observed. Most common TR AEs were G1 diarrhoea (60%), mucositis (30%), rash (20%). 7 pts had PTEN loss and/or PTEN mutations. Clinical benefit rate in pts with PTEN aberration was 2/7 (29%): 1 pCR and 1 SD >12wks, both on 400mg Ipa. A 58-year-old man with PTEN loss had MRI at Cycle 5 showing worsening enhancement suggestive of disease progression. Resection of the lesion showed intense lymphocyte infiltration and pathological CR. He is currently on Cycle 18 with no evidence of disease.

Conclusion: Combination Ipa+A appears safe and tolerable in GBM pts, with 400mg Ipa OD + 1200mg A Q3W declared as RP2D. PTEN loss may be a promising predictive biomarker for response to combination. An expansion cohort enriched with pts with PTEN loss is ongoing. Cytokine and FACS data will be presented at AACR

Table 1.Clinical Benefit Rate of glioblastoma patients stratified according to PTEN aberrationsPTEN statusnBest responseClinical Benefit RatePTEN loss on IHC (H<30)51 pCRa2/7 (29%)1 SD >12 wks, ongoingb3 PDPTEN aberration on NGS but PTEN protein expression pending11 PDcPTEN loss of heterozygozity on PCR11 PDWild type PTEN on NGS or IHC (H≥30)33 PDLegend: IHC = immunohistochemistry; NGS = next generation sequencing; PCR = polymerase chain reaction;pCR = pathologic complete response; SD = stable disease; PD = progressive diseaseaExceptional responder with PTEN H=5 on IHC and splice site 75_79+2delGACCTGT on NGSb PTENY68*; c PTENQ298*

Citation Format: Crescens Tiu, Andrea Biondo, Liam C. Welsh, Timothy L. Jones, Anna Zachariou, Toby Prout, Alison J. Turner, Robert Daly, Igor Vivanco, Christina Yap, Ben Jenkins, Mateus Crespo, Ruth Riisnaes, Suzanne Carreira, Bora Gurel, Nina Tunariu, Anna Minchom, Udai Banerji, Johann S. de Bono, Juanita S. Lopez. Results of the glioblastoma multiforme (GBM) cohort of phase 1 trial Ice-CAP (NCT03673787): Preliminary evidence of antitumour activity of Ipatasertib (Ipa) and Atezolizumab (A) in patients (pts) with PTEN loss [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT120.

Phase I trial of acoustic cluster therapy (ACT) with chemotherapy in patients with liver metastases of gastrointestinal origin (ACTIVATE study)

TPS3145

Background: Response to existing chemotherapeutics (chemo) can be limited by exposure, itself limited by systemic toxicity. Interstitial fluid pressure can impede transport of drugs with, in some cases, <5% of systemic chemo penetrating the target tumour. ACT is an innovative platform technology using sonopermeation to induce ultrasound (US) mediated targeting of therapeutic agent of choice by co-administration of an emulsion of microbubble-microdroplet clusters (PS101) for intravenous injection. Dual-frequency US is applied to tumor tissue to concentrate the drug through expansion and oscillation of the clusters, increasing tumoral penetration. Early pre-clinical models of ACT indicate significant increase in uptake of co-administered product at the US targeted site and have demonstrated enhanced efficacy outcomes with co-administered ACT across a range of cancer models. All studies showed significant benefit in disease response and tumour regression/inhibition versus drug alone. The combination of US, microbubbles and chemo has been shown to be feasible in a clinical setting using commercially available equipment with no additional toxicities. This first in human study will primarily investigate the safety and tolerability of PS101 in combination with chemo together with any differential response in ACT-treated versus control lesions to identify the phase 2 recommended dose. Methods: This is an open label non-randomised study with central blinded assessment of tumor response. The study comprises two parts: Part 1, a dose escalation in a 3+3 design followed by dose expansion in Part 2. Patients with advanced solid tumors with liver metastases for whom FOLFOX/FOLFIRI is considered an appropriate treatment option are eligible for Part 1 (n=6-12); two separate cohorts of patients with liver metastases, one with metastatic colorectal cancer eligible for 1L or 2L standard of care (SOC) FOLFOX/FOLFIRI (n=25) and one with metastatic pancreatic ductal adenocarcinoma (n= 6) eligible for SOC gemcitabine-nab-paclitaxel will be treated in Part 2. The starting dose of PS101 is 20 µL/kg with a maximum feasible dose of 40 µL/kg. In Part 1, after sentinel administration of PS101 for PK profiling and toxicity assessment, patients receive PS101 (given as i.v. bolus x 3) in combination with FOLFOX or FOLFIRI and US (to one target lesion) in four q2w cycles. The DLT evaluation period comprises the PK-assessment period plus two cycles of ACT plus chemo. Patients receive a further two cycles of ACT and chemo prior to evaluation of tumor lesions by CT/MRI at the Week 8 timepoint. Assessment is made of the target lesion and the pre-defined control lesions outside of the US field. Part 1 has enrolled 5 patients without DLT, with part 2 expected to start in mid-2021. Clinical trial information: NCT04021277.

HER3 expression and MEK activation in non-small-cell lung carcinoma

Aim:

We explore HER3 expression in lung adenocarcinoma (adeno-NSCLC) and identify potential mechanisms of HER3 expression.

Materials & methods:

Tumor samples from 45 patients with adeno-NSCLC were analyzed. HER3 and HER2 expression were identified using immunohistochemistry and bioinformatic interrogation of The Cancer Genome Atlas (TCGA).

Results:

HER3 was highly expressed in 42.2% of cases. ERBB3 copy number did not account for HER3 overexpression. Bioinformatic analysis of TCGA demonstrated that MEK activity score (a surrogate of functional signaling) did not correlate with HER3 ligands. ERBB3 RNA expression levels were significantly correlated with MEK activity after adjusting for EGFR expression.

Conclusion:

HER3 expression is common and is a potential therapeutic target by virtue of frequent overexpression and functional downstream signaling.

HER3 expression is common in adeno-NSCLC and is a potential therapeutic target by virtue of frequent overexpression and functional downstream signaling.

Correction to: Radiological evaluation of malignant pleural mesothelioma - defining distant metastatic disease

An amendment to this paper has been published and can be accessed via the original article.

Abstract PS11-05: Updated data from SERENA-1: A Phase 1 dose escalation and expansion study of the next generation oral SERD AZD9833 as a monotherapy and in combination with palbociclib, in women with ER-positive, HER2-negative advanced breast cancer

Background: AZD9833 is an oral selective estrogen receptor (ER) antagonist and degrader (SERD) in Phase 2 clinical development for the treatment of ER+ HER2− breast cancer. Here we report data from Parts C and D of the ongoing Phase 1 study (SERENA-1) examining AZD9833 in combination with palbociclib, together with updated data from Parts A and B examining AZD9833 monotherapy. Methods: SERENA-1 (NCT03616587) is an ongoing open-label Phase 1 study of AZD9833 in pre- and post-menopausal women with ER+, HER2− advanced breast cancer who have previously received ≥1 endocrine therapy and ≤2 prior chemotherapies. Prior treatment with fulvestrant and/or CDK4/6 inhibitors was permitted. The primary objective is to determine the safety and tolerability of once daily (QD) AZD9833, with dose-limiting toxicities (DLTs) in the first 28 days defining the maximum tolerated dose. Secondary objectives include anti-tumor response (including circulating tumor [ct] DNA response) and pharmacokinetics. Parts A (escalation) and B (expansion) assess AZD9833 as a monotherapy, and Parts C (escalation) and D (expansion) assess AZD9833 in combination with palbociclib. Results: At a data cut-off of March 24 2020, 17 patients had received either 150 mg or 300 mg AZD9833 in combination with palbociclib, given according to its product labeling. Eighty patients had received AZD9833 monotherapy at doses of 25, 75, 150, 300, and 450 mg QD. In patients treated with AZD9833 and palbociclib, treatment-related adverse events (AEs; experienced by ≥10% of patients) included visual disturbances*, bradycardia*, asthenia, anemia, QTcF prolongation, nausea, neutropenia, decreased white blood cell count, and vomiting (*combined terms). All instances of AZD9833-related bradycardia were Grade 1. One DLT was observed in the 150 mg cohort: CTCAE Grade 2 visual disturbances, which began on Cycle 1 Day 8 and resolved by Cycle 1 Day 9 following dose interruption. The patient restarted treatment on Cycle 1 Day 15 at 75 mg and continued this dose until data cut-off. No causally related AEs led to discontinuation of AZD9833. The tolerability of AZD9833 with palbociclib was consistent with the observed tolerability profile of AZD9833 monotherapy, and the known tolerability profile of palbociclib. Pharmacokinetic analysis showed similar AZD9833 exposure for monotherapy and palbociclib combination therapy. Similarly, palbociclib exposure was comparable with simulations using a published population pharmacokinetic model. In Part A, ESR1 hotspot mutations were detected in ctDNA at baseline in 26/56 (46%) patients; 13/26 (50%) of these patients achieved a partial response or stable disease at 24 weeks, including 5/10 (50%) with a Y537S ESR1 mutation. Further, in patients with ESR1 mutations and samples available for longitudinal ctDNA analysis, 17/20 (85%) exhibited a reduction or loss of mutant ESR1 on treatment with AZD9833. Efficacy data to be presented include objective response rate and clinical benefit rate at 24 weeks. Of note, unconfirmed partial responses have been observed in Part C after the data cut-off for this abstract. Conclusions: AZD9833 continues to show an encouraging efficacy and dose-dependent safety profile as a monotherapy or in combination with palbociclib. A Phase 2 study comparing the efficacy and safety of three doses of AZD9833 versus fulvestrant (NCT04214288), and a Phase 2 pre-surgical ‘window of opportunity’ study (EUDRA-CT; 2019-003706-2) are ongoing.

Citation Format: Richard Baird, Mafalda Oliveira, Eva Maria Ciruelos Gil, Manish R Patel, Begoña Bermejo de las Heras, Manuel Ruiz-Borrego, Javier García-Corbacho, Anne Armstrong, Udai Banerji, Chris Twelves, Valentina Boni, Jason Incorvati, Peter Kabos, Adam L Cohen, Bruno de Paula, Marta Capelán Rodríguez, Judy S Wang, Christina Hernando, Alejandro Falcón Gonzalez, Ivan Victoria Ruiz, Julia Lai-Kwon, Anosheh Afghani, Christos Vaklavas, Tim Brier, Steven Fox, Bistra Kirova, Teresa Klinowska, Chris Leach, Justin PO Lindemann, Richard Mather, Rhiannon Maudsley, Christopher J Morrow, Nitharsan Sathiyayogan, Andy Sykes, Li Zhang, Erika Hamilton. Updated data from SERENA-1: A Phase 1 dose escalation and expansion study of the next generation oral SERD AZD9833 as a monotherapy and in combination with palbociclib, in women with ER-positive, HER2-negative advanced breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS11-05.

The paradox-breaking panRAF plus SRC family kinase inhibitor, CCT3833, is effective in mutant KRAS-driven cancers

BACKGROUND

KRAS is mutated in ∼90% of pancreatic ductal adenocarcinomas, ∼35% of colorectal cancers and ∼20% of non-small-cell lung cancers. There has been recent progress in targeting G12CKRAS specifically, but therapeutic options for other mutant forms of KRAS are limited, largely because the complexity of downstream signaling and feedback mechanisms mean that targeting individual pathway components is ineffective.

DESIGN

The protein kinases RAF and SRC are validated therapeutic targets in KRAS-mutant pancreatic ductal adenocarcinomas, colorectal cancers and non-small-cell lung cancers and we show that both must be inhibited to block growth of these cancers. We describe CCT3833, a new drug that inhibits both RAF and SRC, which may be effective in KRAS-mutant cancers.

RESULTS

We show that CCT3833 inhibits RAF and SRC in KRAS-mutant tumors in vitro and in vivo, and that it inhibits tumor growth at well-tolerated doses in mice. CCT3833 has been evaluated in a phase I clinical trial (NCT02437227) and we report here that it significantly prolongs progression-free survival of a patient with a G12VKRAS spindle cell sarcoma who did not respond to a multikinase inhibitor and therefore had limited treatment options.

CONCLUSIONS

New drug CCT3833 elicits significant preclinical therapeutic efficacy in KRAS-mutant colorectal, lung and pancreatic tumor xenografts, demonstrating a treatment option for several areas of unmet clinical need. Based on these preclinical data and the phase I clinical unconfirmed response in a patient with KRAS-mutant spindle cell sarcoma, CCT3833 requires further evaluation in patients with other KRAS-mutant cancers.

Research Related Tumour Biopsies in Early-Phase Trials with Simultaneous Molecular Characterisation - a Single Unit Experience

Early-phase cancer clinical trials are becoming increasingly accessible for patients with advanced cancer who have exhausted standard treatment options and later phase trial options. Many of these trials mandate research tissue biopsies. Research biopsies have been perceived as ethically fraught due to the perception of potential coercion of vulnerable human subjects. We performed an audit of two years of practice to assess the safety of ultrasound (US)-guided research biopsies, and to look at the yield of a simultaneous tumour next-generation sequencing (NGS) and immunohistochemistry (IHC) molecular characterisation programme. We show that in our institution, US-guided research biopsies were safe, produced adequate tumour content and in a selected subset who underwent in-house NGS sequencing, showed a high rate of actionable mutations with 30% having a Tier 1 variant. Nevertheless, these research biopsies may only provide direct benefit for a minority of patients and we conclude with a reflection on the importance of obtaining truly informed consent.

Radiological evaluation of malignant pleural mesothelioma - defining distant metastatic disease

BACKGROUND

Malignant pleural mesothelioma (MPM) is traditionally characterized by local destructive spread of the pleura and surrounding tissues. Patient outcomes in MPM with distant metastatic dissemination are lacking.

METHODS

In this retrospective study, we reviewed a cohort of 164 MPM patients referred to a Phase I trials unit, aiming to describe identified metastatic sites, and correlate with clinical outcomes.

RESULTS

67% of patients were diagnosed with distant metastatic disease with a high incidence of bone (19%), visceral (14%), contralateral lung (35%) and peritoneal metastases (22%). Peritoneal metastases were more likely in epithelioid versus biphasic/ sarcomatoid MPM (p = 0.015). Overall survival was 23.8 months with no statistical difference in survival between those with distant metastases and those without.

CONCLUSIONS

This report highlights the frequency of distant metastases and encourages further radiological investigations in the presence of symptoms. In particular, given the relatively high incidence of bone metastases, bone imaging should be considered in advanced MPM clinical workflow and trial protocols. The presence of distant metastases does not appear to have prognostic implications under existing treatment paradigms. This cohort of MPM patients gives an indication of patterns of metastatic spread that are likely to become prevalent as prognosis improves with emerging treatment paradigms.

Intermittent schedules of the oral RAF-MEK inhibitor CH5126766/VS-6766 in patients with RAS/RAF-mutant solid tumours and multiple myeloma: a single-centre, open-label, phase 1 dose-escalation and basket dose-expansion study

BACKGROUND

CH5126766 (also known as VS-6766, and previously named RO5126766), a novel MEK-pan-RAF inhibitor, has shown antitumour activity across various solid tumours; however, its initial development was limited by toxicity. We aimed to investigate the safety and toxicity profile of intermittent dosing schedules of CH5126766, and the antitumour activity of this drug in patients with solid tumours and multiple myeloma harbouring RAS-RAF-MEK pathway mutations.

METHODS

We did a single-centre, open-label, phase 1 dose-escalation and basket dose-expansion study at the Royal Marsden National Health Service Foundation Trust (London, UK). Patients were eligible for the study if they were aged 18 years or older, had cancers that were refractory to conventional treatment or for which no conventional therapy existed, and if they had a WHO performance status score of 0 or 1. For the dose-escalation phase, eligible patients had histologically or cytologically confirmed advanced or metastatic solid tumours. For the basket dose-expansion phase, eligible patients had advanced or metastatic solid tumours or multiple myeloma harbouring RAS-RAF-MEK pathway mutations. During the dose-escalation phase, we evaluated three intermittent oral schedules (28-day cycles) in patients with solid tumours: (1) 4·0 mg or 3·2 mg CH5126766 three times per week; (2) 4·0 mg CH5126766 twice per week; and (3) toxicity-guided dose interruption schedule, in which treatment at the recommended phase 2 dose (4·0 mg CH5126766 twice per week) was de-escalated to 3 weeks on followed by 1 week off if patients had prespecified toxic effects (grade 2 or worse diarrhoea, rash, or creatinine phosphokinase elevation). In the basket dose-expansion phase, we evaluated antitumour activity at the recommended phase 2 dose, determined from the dose-escalation phase, in biomarker-selected patients. The primary endpoints were the recommended phase 2 dose at which no more than one out of six patients had a treatment-related dose-limiting toxicity, and the safety and toxicity profile of each dosing schedule. The key secondary endpoint was investigator-assessed response rate in the dose-expansion phase. Patients who received at least one dose of the study drug were evaluable for safety and patients who received one cycle of the study drug and underwent baseline disease assessment were evaluable for response. This trial is registered with ClinicalTrials.gov, NCT02407509.

FINDINGS

Between June 5, 2013, and Jan 10, 2019, 58 eligible patients were enrolled to the study: 29 patients with solid tumours were included in the dose-escalation cohort and 29 patients with solid tumours or multiple myeloma were included in the basket dose-expansion cohort (12 non-small-cell lung cancer, five gynaecological malignancy, four colorectal cancer, one melanoma, and seven multiple myeloma). Median follow-up at the time of data cutoff was 2·3 months (IQR 1·6-3·5). Dose-limiting toxicities included grade 3 bilateral retinal pigment epithelial detachment in one patient who received 4·0 mg CH5126766 three times per week, and grade 3 rash (in two patients) and grade 3 creatinine phosphokinase elevation (in one patient) in those who received 3·2 mg CH5126766 three times per week. 4·0 mg CH5126766 twice per week (on Monday and Thursday or Tuesday and Friday) was established as the recommended phase 2 dose. The most common grade 3-4 treatment-related adverse events were rash (11 [19%] patients), creatinine phosphokinase elevation (six [11%]), hypoalbuminaemia (six [11%]), and fatigue (four [7%]). Five (9%) patients had serious treatment-related adverse events. There were no treatment-related deaths. Eight (14%) of 57 patients died during the trial due to disease progression. Seven (27% [95% CI 11·6-47·8]) of 26 response-evaluable patients in the basket expansion achieved objective responses.

INTERPRETATION

To our knowledge, this is the first study to show that highly intermittent schedules of a RAF-MEK inhibitor has antitumour activity across various cancers with RAF-RAS-MEK pathway mutations, and that this inhibitor is tolerable. CH5126766 used as a monotherapy and in combination regimens warrants further evaluation.

FUNDING

Chugai Pharmaceutical.

Phase I Trial of the PARP Inhibitor Olaparib and AKT Inhibitor Capivasertib in Patients with BRCA1/2- and Non-BRCA1/2-Mutant Cancers

Preclinical studies have demonstrated synergy between PARP and PI3K/AKT pathway inhibitors in BRCA1 and BRCA2 (BRCA1/2)-deficient and BRCA1/2-proficient tumors. We conducted an investigator-initiated phase I trial utilizing a prospective intrapatient dose- escalation design to assess two schedules of capivasertib (AKT inhibitor) with olaparib (PARP inhibitor) in 64 patients with advanced solid tumors. Dose expansions enrolled germline BRCA1/2-mutant tumors, or BRCA1/2 wild-type cancers harboring somatic DNA damage response (DDR) or PI3K-AKT pathway alterations. The combination was well tolerated. Recommended phase II doses for the two schedules were: olaparib 300 mg twice a day with either capivasertib 400 mg twice a day 4 days on, 3 days off, or capivasertib 640 mg twice a day 2 days on, 5 days off. Pharmacokinetics were dose proportional. Pharmacodynamic studies confirmed phosphorylated (p) GSK3β suppression, increased pERK, and decreased BRCA1 expression. Twenty-five (44.6%) of 56 evaluable patients achieved clinical benefit (RECIST complete response/partial response or stable disease ≥ 4 months), including patients with tumors harboring germline BRCA1/2 mutations and BRCA1/2 wild-type cancers with or without DDR and PI3K-AKT pathway alterations. SIGNIFICANCE: In the first trial to combine PARP and AKT inhibitors, a prospective intrapatient dose- escalation design demonstrated safety, tolerability, and pharmacokinetic-pharmacodynamic activity and assessed predictive biomarkers of response/resistance. Antitumor activity was observed in patients harboring tumors with germline BRCA1/2 mutations and BRCA1/2 wild-type cancers with or without somatic DDR and/or PI3K-AKT pathway alterations.This article is highlighted in the In This Issue feature, p. 1426.

Phase I Trial of First-in-Class ATR Inhibitor M6620 (VX-970) as Monotherapy or in Combination With Carboplatin in Patients With Advanced Solid Tumors

PURPOSE

Preclinical studies demonstrated that ATR inhibition can exploit synthetic lethality (eg, in cancer cells with impaired compensatory DNA damage responses through ATM loss) as monotherapy and combined with DNA-damaging drugs such as carboplatin.

PATIENTS AND METHODS

This phase I trial assessed the ATR inhibitor M6620 (VX-970) as monotherapy (once or twice weekly) and combined with carboplatin (carboplatin on day 1 and M6620 on days 2 and 9 in 21-day cycles). Primary objectives were safety, tolerability, and maximum tolerated dose; secondary objectives included pharmacokinetics and antitumor activity; exploratory objectives included pharmacodynamics in timed paired tumor biopsies.

RESULTS

Forty patients were enrolled; 17 received M6620 monotherapy, which was safe and well tolerated. The recommended phase II dose (RP2D) for once- or twice-weekly administration was 240 mg/m2. A patient with metastatic colorectal cancer harboring molecular aberrations, including ATM loss and an ARID1A mutation, achieved RECISTv1.1 complete response and maintained this response, with a progression-free survival of 29 months at last assessment. Twenty-three patients received M6620 with carboplatin, with mechanism-based hematologic toxicities at higher doses, requiring dose delays and reductions. The RP2D for combination therapy was M6620 90 mg/m2 with carboplatin AUC5. A patient with advanced germline BRCA1 ovarian cancer achieved RECISTv1.1 partial response and Gynecologic Cancer Intergroup CA125 response despite being platinum refractory and PARP inhibitor resistant. An additional 15 patients had RECISTv1.1 stable disease as best response. Pharmacokinetics were dose proportional and exceeded preclinical efficacious levels. Pharmacodynamic studies demonstrated substantial inhibition of phosphorylation of CHK1, the downstream ATR substrate.

CONCLUSION

To our knowledge, this report is the first of an ATR inhibitor as monotherapy and combined with carboplatin. M6620 was well tolerated, with target engagement and preliminary antitumor responses observed.

First-in-Human Study of AT13148, a Dual ROCK-AKT Inhibitor in Patients with Solid Tumors

PURPOSE

AT13148 is an oral AGC kinase inhibitor, which potently inhibits ROCK and AKT kinases. In preclinical models, AT13148 has been shown to have antimetastatic and antiproliferative activity.

PATIENTS AND METHODS

The trial followed a rolling six design during dose escalation. An intrapatient dose escalation arm to evaluate tolerability and a biopsy cohort to study pharmacodynamic effects were later added. AT13148 was administered orally three days a week (Mon-Wed-Fri) in 28-day cycles. Pharmacokinetic profiles were assessed using mass spectrometry and pharmacodynamic studies included quantifying p-GSK3β levels in platelet-rich plasma (PRP) and p-cofilin and p-MLC2 levels in tumor biopsies.

RESULTS

Fifty-one patients were treated on study. The safety of 5-300 mg of AT13148 was studied. Further, the doses of 120-180-240 mg were studied in an intrapatient dose escalation cohort. The dose-limiting toxicities included hypotension (300 mg), pneumonitis, and elevated liver enzymes (240 mg), and skin rash (180 mg). The most common side effects were fatigue, nausea, headaches, and hypotension. On the basis of tolerability, 180 mg was considered the maximally tolerated dose. At 180 mg, mean C max and AUC were 400 nmol/L and 13,000 nmol/L/hour, respectively. At 180 mg, ≥50% reduction of p-cofilin was observed in 3 of 8 posttreatment biopsies.

CONCLUSIONS

AT13148 was the first dual potent ROCK-AKT inhibitor to be investigated for the treatment of solid tumors. The narrow therapeutic index and the pharmacokinetic profile led to recommend not developing this compound further. There are significant lessons learned in designing and testing agents that simultaneously inhibit multiple kinases including AGC kinases in cancer.

Radiological Patterns of Drug-induced Interstitial Lung Disease (DILD) in Early-phase Oncology Clinical Trials

PURPOSE

Drug-induced interstitial lung disease (DILD) is a rare, but potentially fatal toxicity. Clinical and radiological features of DILD in the early experimental setting are poorly described.

PATIENTS AND METHODS

A total of 2,499 consecutive patients with advanced cancer on phase I clinical trials were included. DILD was identified by a dedicated radiologist and investigators, categorized per internationally recognized radiological patterns, and graded per Common Terminology Criteria for Adverse Events (CTCAE) and the Royal Marsden Hospital (RMH) DILD score. Clinical and radiological features of DILD were analyzed.

RESULTS

Sixty patients overall (2.4%) developed DILD. Median time to onset of DILD was 63 days (range, 14-336 days). A total of 45% of patients who developed DILD were clinically asymptomatic. Incidence was highest in patients receiving drug conjugates (7.4%), followed by inhibitors of the PI3K/AKT/mTOR pathway (3.9%). The most common pattern seen was hypersensitivity pneumonitis (33.3%), followed by nonspecific interstitial pneumonia (30%), and cryptogenic organizing pneumonia (26.7%). A higher DILD score [OR, 1.47, 95% confidence interval (CI), 1.19-1.81; P < 0.001] and the pattern of DILD (OR, 5.83 for acute interstitial pneumonia; 95% CI, 0.38-90.26; P = 0.002) were significantly associated with a higher CTCAE grading. The only predictive factor for an improvement in DILD was an interruption of treatment (OR, 0.05; 95% CI, 0.01-0.35; P = 0.01).

CONCLUSIONS

DILD in early-phase clinical trials is a toxicity of variable onset, with diverse clinical and radiological findings. Radiological findings precede clinical symptoms. The extent of the affected lung parenchyma, scored by the RMH DILD score, correlates with clinical presentation. Most events are low grade, and improve with treatment interruption, which should be considered early.

Abstract CT129: HyPeR: A phase 1, dose escalation and expansion trial of guadecitabine (SGI-110), a second-generation hypomethylating agent in combination with pembrolizumab (MK3475) in patients with refractory solid tumors

Background: Methylation is reported to support cancer immune tolerance. We conducted a phase 1 dose-escalation trial [NCT02998567] of combination guadecitabine (G; DNA hypomethylating agent) and pembrolizumab (P) in patients (pts) with advanced cancers. We hypothesized that G can normalize the expression of epigenetically suppressed immune genes, increase interferon producing tumor-infiltrating lymphocytes (TILs), and enhance the anticancer activity of P. Methods: In dose escalation (Es), pts received G (45 mg/m2 or 30 mg/m2, administered SC on days 1-4) with P (200 mg, administered IV starting from cycle 2 onwards) as outpatient Q3W; in expansion (Ex), the RP2D of G (30 mg/m2) with P (200 mg) Q3W was administered. Pre-treatment and on-treatment tumor biopsies were evaluated for PD-L1 expression, tumor infiltrating lymphocytes, gene expression by RNAseq and methylome studies. Longitudinal analyses of peripheral blood CD3, CD4 and CD8 lymphocytes by flow cytometry were performed. Results: Overall, 34 pts (Es, n = 14; Ex, n = 20) were evaluable for safety. The most common treatment-related adverse events (TRAEs) were neutropenia (n = 21), fatigue (n = 6) and thrombocytopenia (n = 3), diarrhea (n = 2). G3+ TRAEs were neutropenia (n = 14), febrile neutropenia (n = 4), raised ALP (n = 1), raised AST (n=1), colitis (n = 1), diarrhoea (n = 1) and lung infection (n = 1). Two DLTs (neutropenia, febrile neutropenia) were reported at G 45mg/m2 with none reported at G 30mg/m2. There were no treatment-related deaths. In total, 28 pts (Es, n = 12; Ex, n = 16) were evaluable for antitumor activity studies (≥2 scans); ORR (CR+PR) and DCR (CR+PR+SD) were 3% and 57%; 10/15 pts with non-small cell lung cancer (13 pts resistant/refractory to PD-1/PD-L1 targeting agents) were evaluable, with a DCR of 80% and 5 pts having DCR &gt; 6 months with 8 pts remaining on study treatment. Overall, 25 paired biopsies were obtained. Using LINE1 sequences to study global methylation, both tumor biopsies and peripheral blood showed reduced methylation post-G treatment. Preliminary data on tumor-infiltrating lymphocytes assessed by multicolor immunofluorescence in 9 paired biopsies showed a numerical increase in median values of T-helper (CD4+FOXP3-) (10.20 to 19.70, p = 0.5469), T-regulatory (CD4+FOXP3+) (5.1 to 6.7, p=0.8438), and T-cytotoxic (CD8+) cell densities (2.7 to 7.4, p=0.6523) . Comparing with matched pre-treatment, on treatment tumor had numerical increases in interferon alpha and gamma response pathway activation in serial biopsy RNAseq analyses but did not reach significance. Conclusions: G plus P resulted in no unexpected toxicities with evidence suggestive of biological and anti-cancer activity.

Citation Format: Dionysis Papadatos-Pastos, Abhijit Pal, Melek Akay, Malaka Ameratunga, Sanjena Mithra, Joo-Ern Ang, Sofia Levva, Reece Caldwell, Ruth Riisnaes, Mateus Crespo, Wei Yuan, George Seed, Bora Gurel, Ines Figueiredo, Rita Pereira, Susana Miranda, Anna Ferreira, Suzanne Carreira, Claudia Bertan, Chloe Baker, Ricardo Morilla, Robert Brown, Nahal Masrour, Toby Prout, Anna Zachariou, Alison Turner, Mona Parmar, Mark Van de Velde, Ben Jenkins, Christina Yap, Nina Tunariu, Udai Banerji, Juanita Lopez, Anna Minchom, Johann De Bono. HyPeR: A phase 1, dose escalation and expansion trial of guadecitabine (SGI-110), a second-generation hypomethylating agent in combination with pembrolizumab (MK3475) in patients with refractory solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT129.

Abstract CT141: Phase 1 trial of MOv18, a first-in-class IgE antibody therapy for cancer

Background: All antibodies approved for the treatment of cancer are monoclonal IgGs, and no IgE therapy has yet been tested in humans. The biology of IgE, compared with IgG, offers potential for enhanced immune surveillance and superior effector cell potency against tumor cells. IgE antibodies in preclinical cancer models are not associated with allergic toxicity even in immunocompetent animals, and in vivo efficacy compares favorably with equivalent IgGs.

Methods: We conducted a first-in-human first-in-class trial of MOv18, a chimeric monoclonal IgE, in patients with solid tumors expressing folate receptor-alpha, the antigen recognized by this antibody. Antigen expression was deemed positive in the presence of &gt;5% membrane staining of any intensity using the mouse clone BN3.2. Intravenous treatment was administered weekly for 6 weeks, then two-weekly. The trial incorporated pre-treatment skin prick testing with MOv18 IgE, and an ex vivo basophil activation test (BAT) using patient whole blood, with the aim of predicting systemic allergic toxicity and excluding patients at potential risk. Safety, efficacy, markers of immune response, and pharmacokinetics have been evaluated in 24 patients to date, at total doses ranging from 0.07 to 3.0mg.

Results: Treatment was well tolerated in almost all patients. The most common toxicity was readily manageable urticaria, without systemic symptoms, signs or tryptase elevation. One patient treated at the 0.5mg dose experienced anaphylaxis, with tryptase elevation, despite a negative pre-dose skin prick test. This was the only patient in the trial with baseline circulating basophils that could be activated by ex vivo exposure to MOv18 IgE. This BAT assay was subsequently used to ensure no further patient with reactive basophils was exposed. Maximum tolerated dose has not yet been reached. Dose-dependent increases in Cmax were observed, and plasma concentrations of 70-100ng/mL achieved at the 1.5mg dose are comparable to typical levels of endogenous IgE. No consistent anti-drug antibody response has been detected. Preliminary evidence of anti-tumor activity was seen in a patient with ovarian cancer at a total MOv18 IgE dose of 0.7mg. Shrinkage of peritoneal metastases was accompanied by a tumor marker reduction meeting Gynecologic Cancer InterGroup criteria for response.

Conclusions: These results support for the first time the safety of IgE as a treatment for cancer, and provide preliminary evidence for anti-tumor efficacy of this new therapeutic class. The mechanism of cutaneous toxicity is being investigated. Clinical testing of class-switched IgE versions of approved IgG-based therapeutic antibodies is warranted.

Citation Format: James Spicer, Bristi Basu, Ana Montes, Udai Banerji, Rebecca Kristeleit, Gareth J. Veal, Christopher Corrigan, Stephen Till, George Nintos, Timothy Brier, Ionut G. Funingana, Joo Ern Ang, Kam Zaki, Annie Griffin, Claire Barton, Paul Jones, Sarah Mellor, Susan Brook, Katie Stoddart, Christopher Selkirk, Simon Carroll, Heike Lentfer, Natalie Woodman, Amy Pope, Giulia Pellizzari, Mano Nakamura, Kristina M. Ilieva, Atousa Khiabany, Chara Stavraka, Hannah Gould, Jitesh Chauhan, Heather Bax, Sarah Pinder, Debra Josephs, Sophia Karagiannis. Phase 1 trial of MOv18, a first-in-class IgE antibody therapy for cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT141.

Abstract CT140: Proof-of-concept evidence of immune modulation by blockade of the phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway in the phase I dose escalation study of Ipatasertib (Ipa) in combination with atezolizumab (A) in patients (pts) with advanced solid tumors (Ice-CAP)

Background: Hyperactivation of the PI3K/AKT pathway correlates with impaired anti-tumor responses, including reduced T cell infiltration into tumor, and reduced efficacy of immune checkpoint inhibitors. Blockade of this pathway synergizes with PD-L1/PD-1 axis blockade preclinically.

Methods: This Phase I clinical trial (NCT03673787) assessed the safety, pharmacodynamic, and preliminary clinical activity of Ipa (200mg or 400mg OD) given in combination with A 1200mg q3 wk in refractory pts. Serial paired blood and tumor samples were analysed to interrogate the effect of Ipa on the tumor micro-environment and host immune system prior to the addition of the immune check point inhibitor, A.

Results: 18 adult pts were treated in dose escalation. Median age 49 yrs. All pts had ECOG PS 0-1 and median 7 prior therapies. Most common TRAEs (&gt;15%) were mild Gr1-2 diarrhea (56%), rash (50%), fatigue (33%), nausea (33%), raised ALT/AST (33%), headache (28%) and arthralgia (22%). 1 pt had G2 systemic immune activation; 2 pts had G3 rash, both rapidly reversible. 1 DLT of G3 raised ALT seen at 200mg (1 DLT/9 evaluable pts) but none at 400mg (0 DLT/6). Of 14 RECIST evaluable patients, there were 2 confirmed PRs, and 5 SD (clinical benefit rate 50%). Reductions of CD4+FOXP3+ Tregs in tumor microenvironment were seen after 2wks of single agent Ipa, regardless of PIK3/AKT somatic mutation status (Table 1). Responding pts had a &gt;400% median increase in intra-tumoral CD8+ Teff cell infiltration, effectively switching from a desert phenotype to an inflamed phenotype. Paired changes in FACS, transcriptome and cytokine will also be presented.Conclusions: The RP2D of Ipa 400mg OD combination with A was well tolerated with early efficacy signals. Further biomarker work is ongoing and will be evaluated in expansion cohorts.

Table 1:Changes in immune cell populations as assessed by multicolour Immunofluorescence in paired biopsies of breast/gynae patients, % change in cell number/mm2 from baseline (median [min,max$])&Post 2 weeks single agent Ipatasertib(n=9)Post 1 cycle of combination Ipatasertib and Atezolizumab(n=7)CD4+FOXP3+Tregs cellsCD 8+ Teff cellsCD4+FOXP3+Tregs cellsCD 8+ Teff cellsIntra-tumourstromaIntra-tumourstromaIntra-tumourstromaIntra-tumourstromaAll patients-23.9*[-89.7, BL0]-30.0*[-91.6, BL0]-37.7*[-84.4, -24.5]-28.4[-92.4, 259.8]335.9[-44.0,BL0]45.4[-51.0, BL0]59.6[-60.6,493.3]64.7[-51.7,293.3]Stratified by somatic PI3K/AKT/PTEN mutational statusPathogenic mutations (mt)11.1[-82.2, BL0]#-10.7[-91.6, BL0]Φnsnsnsns-30.5[-60.6,-0.5]11.3[-51.7,50.0]Wildtype (wt)-63.1[-89.7,19.0]#-47.5[-77.0,11.1]Φnsnsnsns426.5[59.6,493.3]126.7[79.4,293.3]Stratified by responseResponders (PR + SD&gt;4 cycles). 1 ER+ HER2+ breast cancer (wt), 1 ER+ HER2- breast cancer (wt)459.9[426.5,493.3]@103.1[79.4,126.7]Non-responders (PD at 4 cycles) 1 cervical cancer, 4 ER+ breast cancer-0.5[-60.6, 59.6]@30.6[-51.7,293.3]*significant change (p≤0.05; Wilcoxon sign-rank test) from baseline, $maximum values denoted by BL0indicate that the baseline value was zero, and so percentage change from baseline is not defined. For the analysis, the baseline value has been replaced by a nominal value of 0.1 so that a large percentage increase is associated with these cases. Note that these large percentage increases do not affect the non-parametric statistical tests used.#no significant difference in distribution of reduction in intra-tumoural CD4+ FOXP3+Tregsbetween pts with pathogenic mutations in PI3K/AKT and those without (p=0.30; Wilcoxon rank-sum test)Φno significant difference in distribution of reduction in stromal CD4+FOXP3+Tregsbetween pts with pathogenic mutations in PI3K/AKT and those without (p=0.44; Wilcoxon rank-sum test) @ difference between responders and non-responders p=0.083; Wilcoxon rank-sum test)mt pathogenic mutations in PI3K/AKT and PTEN as per COSMIC database present in tumour or PTEN loss by IHC. wt no pathogenic mutations in PI3K/AKT and PTEN as per COSMIC database detected in tumour and intact PTEN expression by IHC. &exploratory analyses with no adjustment for multiple testing

Citation Format: Juanita S. Lopez, Andrea Biondo, Crescens Tiu, Mariana Scaranti, Malaka Ameratunga, Anna Zachariou, Alison Turner, Nina Tunariu, Toby Prout, Mona Parmar, Hannah Badham, Karen Swales, Wei Yuan, Ricardo Morilla, Mateus Crespo, Rob Daly, Ines Figueiredo, Bora Gurel, Rita Pereira, Ruth Riisnaes, Igor Vivanco, Anna Minchom, Ben Jenkins, Christina Yap, Udai Banerji, Johann De Bono. Proof-of-concept evidence of immune modulation by blockade of the phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway in the phase I dose escalation study of Ipatasertib (Ipa) in combination with atezolizumab (A) in patients (pts) with advanced solid tumors (Ice-CAP) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT140.

Capivasertib, an AKT Kinase Inhibitor, as Monotherapy or in Combination with Fulvestrant in Patients with AKT1 E17K-Mutant, ER-Positive Metastatic Breast Cancer

PURPOSE

The activating mutation AKT1 E17K occurs in approximately 7% of estrogen receptor-positive (ER+) metastatic breast cancer (MBC). We report, from a multipart, first-in-human, phase I study (NCT01226316), tolerability and activity of capivasertib, an oral AKT inhibitor, as monotherapy or combined with fulvestrant in expansion cohorts of patients with AKT1 E17K-mutant ER+ MBC.

PATIENTS AND METHODS

Patients with an AKT1 E17K mutation, detected by local (next-generation sequencing) or central (plasma-based BEAMing) testing, received capivasertib 480 mg twice daily, 4 days on, 3 days off, weekly or 400 mg twice daily combined with fulvestrant at the labeled dose. Study endpoints included safety, objective response rate (ORR; RECIST v1.1), progression-free survival (PFS), and clinical benefit rate at 24 weeks (CBR24). Biomarker analyses were conducted in the combination cohort.

RESULTS

From October 2013 to August 2018, 63 heavily pretreated patients received capivasertib (20 monotherapy, 43 combination). ORR was 20% with monotherapy, and within the combination cohort was 36% in fulvestrant-pretreated and 20% in fulvestrant-naïve patients, although the latter group may have had more aggressive disease at baseline. AKT1 E17K mutations were detectable in plasma by BEAMing (95%, 41/43), droplet digital PCR (80%, 33/41), and next-generation sequencing (76%, 31/41). A ≥50% decrease in AKT1 E17K at cycle 2 day 1 was associated with improved PFS. Combination therapy appeared more tolerable than monotherapy [most frequent grade ≥3 adverse events: rash (9% vs. 20%), hyperglycemia (5% vs. 30%), diarrhea (5% vs. 10%)].

CONCLUSIONS

Capivasertib demonstrated clinically meaningful activity in heavily pretreated patients with AKT1 E17K-mutant ER+ MBC, including those with prior disease progression on fulvestrant. Tolerability and activity appeared improved by the combination.