TRAFIC: statistical design and analysis plan for a pragmatic early phase 1/2 Bayesian adaptive dose escalation trial in rheumatoid arthritis

Background

Adaptive model-based dose-finding designs have demonstrated advantages over traditional rule-based designs but have increased statistical complexity but uptake has been slow especially outside of cancer trials. TRAFIC is a multi-centre, early phase trial in rheumatoid arthritis incorporating a model-based design.

Methods

A Bayesian adaptive dose-finding phase I trial rolling into a single-arm, single-stage phase II trial. Model parameters for phase I were chosen via Monte Carlo simulation evaluating objective performance measures under clinically relevant scenarios and incorporated stopping rules for early termination. Potential designs were further calibrated utilising dose transition pathways.

Discussion

TRAFIC is an MRC-funded trial of a re-purposed treatment demonstrating that it is possible to design, fund and implement a model-based phase I trial in a non-cancer population within conventional research funding tracks and regulatory constraints. The phase I design allows borrowing of information from previous trials, all accumulated data to be utilised in decision-making, verification of operating characteristics through simulation, improved understanding for management and oversight teams through dose transition pathways. The rolling phase II design brings efficiencies in trial conduct including site and monitoring activities and cost.

TRAFIC is the first funded model-based dose-finding trial in inflammatory disease demonstrating that small phase I/II trials can have an underlying statistical basis for decision-making and interpretation.

Trial registration

Trials Registration: ISRCTN, ISRCTN36667085. Registered on September 26, 2014.

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.

Would the Recommended Dose Have Been Different Using Novel Dose-Finding Designs? Comparing Dose-Finding Designs in Published Trials

Simulation studies have shown that novel designs such as the continual reassessment method and the Bayesian optimal interval (BOIN) design outperform the 3 + 3 design by recommending the maximum tolerated dose (MTD) more often, using less patients, and allotting more patients to the MTD. However, it is not clear whether these novel designs would have yielded different results in the context of real-world dose-finding trials. This is a commonly mentioned reason for the continuous use of 3 + 3 designs for oncology trials, with investigators considering simulation studies not sufficiently convincing to warrant the additional design complexity of novel designs.

METHODS

We randomly sampled 60 published dose-finding trials to obtain 22 that used the 3 + 3 design, identified an MTD, published toxicity data, and had more than two dose levels. We compared the published MTD with the estimated MTD using the continual reassessment method and BOIN using target toxicity rates of 25% and 30% and toxicity data from the trial. Moreover, we compared patient allocation and sample size assuming that these novel designs had been implemented.

RESULTS

Model-based designs chose dose levels higher than the published MTD in about 40% of the trials, with estimated and observed toxicity rates closer to the target toxicity rates of 25% and 30%. They also assigned less patients to suboptimal doses and permitted faster dose escalation.

CONCLUSION

This study using published dose-finding trials shows that novel designs would recommend different MTDs and confirms the advantages of these designs compared with the 3 + 3 design, which were demonstrated by simulation studies.

A comprehensive influenza reporter virus panel for high-throughput deep profiling of neutralizing antibodies

Broadly neutralizing antibodies (bnAbs) have been developed as potential countermeasures for seasonal and pandemic influenza. Deep characterization of these bnAbs and polyclonal sera provides pivotal understanding for influenza immunity and informs effective vaccine design. However, conventional virus neutralization assays require high-containment laboratories and are difficult to standardize and roboticize. Here, we build a panel of engineered influenza viruses carrying a reporter gene to replace an essential viral gene, and develop an assay using the panel for in-depth profiling of neutralizing antibodies. Replication of these viruses is restricted to cells expressing the missing viral gene, allowing it to be manipulated in a biosafety level 2 environment. We generate the neutralization profile of 24 bnAbs using a 55-virus panel encompassing the near-complete diversity of human H1N1 and H3N2, as well as pandemic subtype viruses. Our system offers in-depth profiling of influenza immunity, including the antibodies against the hemagglutinin stem, a major target of universal influenza vaccines.

Targeting synovial fibroblast proliferation in rheumatoid arthritis (TRAFIC): an open-label, dose-finding, phase 1b trial

Background

Current rheumatoid arthritis therapies target immune inflammation and are subject to ceiling effects. Seliciclib is an orally available cyclin-dependent kinase inhibitor that suppresses proliferation of synovial fibroblasts—cells not yet targeted in rheumatoid arthritis. Part 1 of this phase 1b/2a trial aimed to establish the maximum tolerated dose of seliciclib in patients with active rheumatoid arthritis despite ongoing treatment with TNF inhibitors, and to evaluate safety and pharmacokinetics.

Methods

Phase 1b of the TRAFIC study was a non-randomised, open-label, dose-finding trial done in rheumatology departments in five UK National Health Service hospitals. Eligible patients (aged ≥18 years) fulfilled the 1987 American College of Rheumatology (ACR) or the 2010 ACR–European League Against Rheumatism classification criteria for rheumatoid arthritis and had moderate to severe disease activity (a Disease Activity Score for 28 joints [DAS28] of ≥3·2) despite stable treatment with anti-TNF therapy for at least 3 months before enrolment. Participants were recruited sequentially to a maximum of seven cohorts of three participants each, designated to receive seliciclib 200 mg, 400 mg, 600 mg, 800 mg, or 1000 mg administered in 200 mg oral capsules. Sequential cohorts received doses determined by a restricted, one-stage Bayesian continual reassessment model, which determined the maximum tolerated dose (the primary outcome) based on a target dose-limiting toxicity rate of 35%. Seliciclib maximum concentration (C_max) and area under the plasma concentration time curve 0–6 h (AUC_0–6) were measured. This study is registered with ISRCTN, ISRCTN36667085.

Findings

Between Oct 8, 2015, and Aug 15, 2017, 37 patients were screened and 15 were enrolled to five cohorts and received seliciclib, after which the trial steering committee and the data monitoring committee determined that the maximum tolerated dose could be defined. In addition to a TNF inhibitor, ten (67%) enrolled patients were taking conventional synthetic disease modifying antirheumatic drugs. The maximum tolerated dose of seliciclib was 400 mg, with an estimated dose-limiting toxicity probability of 0·35 (90% posterior probability interval 0·18–0·52). Two serious adverse events occurred (one acute kidney injury in a patient receiving the 600 mg dose and one drug-induced liver injury in a patient receiving the 400 mg dose), both considered to be related to seliciclib and consistent with its known safety profile. 65 non-serious adverse events occurred during the trial, 50 of which were considered to be treatment related. Most treatment-related adverse events were mild; 20 of the treatment-related non-serious adverse events contributed to dose-limiting toxicities. There were no deaths. Average C_max and AUC_0–6 were two-times higher in participants developing dose-limiting toxicities.

Interpretation

The maximum tolerated dose of seliciclib has been defined for rheumatoid arthritis refractory to TNF blockade. No unexpected safety concerns were identified to preclude ongoing clinical evaluation in a formal efficacy trial.

Funding

UK Medical Research Council, Cyclacel, Research into Inflammatory Arthritis Centre (Versus Arthritis), and the National Institute of Health Research Newcastle and Birmingham Biomedical Research Centres and Clinical Research Facilities.

Putative biomarkers of response to anti-PD-1 therapy in metastatic castration-resistant prostate cancer (mCRPC)

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Background: Metastatic castration resistant prostate cancer (mCRPC) is a heterogeneous disease in which molecular stratification is needed to improve clinical outcomes. Targeting programmed cell death protein 1 (PD-1) elicits durable antitumor responses in multiple cancer types. Putative biomarkers predictive of response to anti-PD-1 therapies include programmed death-ligand-1 (PD-L1), tumour mutational burden (TMB), T cell-inflamed 18-gene expression profile (GEP), and DNA repair defects. Objective: To study potential biomarkers of response in mCRPC to anti-PD-1 therapy (PD-L1, GEP, mismatch repair (MMR) protein), other biomarkers of interest including BRCA2, PALB2, CDK12, PTEN, TP53, SOX2, and to determine association with clinical outcomes. Methods: The study population included 100 men with mCRPC treated at the Royal Marsden Hospital with available fresh mCRPC biopsy tissue. All men had received at least one line of therapy with a next generation hormonal agent and one line of taxane-based chemotherapy. Clinical characteristics and outcomes were extracted from medical records. mCRPC biopsies were assayed by whole exome sequencing (WES), targeted next generation sequencing (NGS), RNA sequencing (RNAseq), GEP score (Nanostring), PD-L1 immunohistochemistry (IHC; DAKO 22C3 assay), SOX2 IHC, ATM IHC. Correlations among these biomarkers and clinical outcomes were assessed. Results: The median age of patients was 68.0 years; 46/84 (54.8%) had de novo metastatic disease at diagnosis and 24/100 (24.0%) patients had visceral disease. Median follow-up from mCRPC biopsy was 56.2 months. The prevalence of loss of protein expression by IHC and/or pathogenic mutation by NGS of MMR was 7/100 (7%). Loss of PTEN and ATM by IHC was 29/100 (29%) and 13/100 (13%) respectively. SOX2 expression (defined as expression in >5% of cells) was 27/100 (27%). The prevalence of TP53 mutation was 25/100 (25%); deleterious alterations of BRCA2 was 9/100 (9%), CDK12 3/100 (3%) and PALB2 1/100 (1%). PDL1 and GEP results were available for 70 and 93 samples respectively. PD-L1 was expressed (combined positive score ≥1) in 24 (33%) mCRPC biopsies; 23 (26%) had high GEP scores (> -0.318). PD-L1 and GEP expression were positively correlated (Phi 0.63). No other biomarkers showed strong correlations. Of 5 samples with MMR loss for which PD-L1 was available, 1 (20%) had PD-L1 ≥1; one of the CDK12 samples had PD-L1 ≥1 (33%). 0/6 BRCA2 mutated biopsies expressed PD-L1 (0%). Based on univariate analysis, PD-L1 expression [HR: 1.75 (1.00;3.06), p=0.045], high GEP score [HR: 2.00 (1.18;3.39), p=0.0083] and SOX2 expression [HR: 1.81 (1.12;2.94), p=0.015] were associated with worse overall survival (OS). No other biomarkers associated with OS. Conclusions: PD-L1 IHC expression was detected in 33% of mCRPC patients and associated with high GEP score. Higher PD-L1, GEP, and SOX2 expression were associated with poor prognosis.

Newcastle Disease Virus-Like Particles Displaying Prefusion-Stabilized SARS-CoV-2 Spikes Elicit Potent Neutralizing Responses

The COVID-19 pandemic highlights an urgent need for vaccines that confer protection from SARS-CoV-2 infection. One approach to an effective COVID-19 vaccine may be through the display of SARS-CoV-2 spikes on the surface of virus-like particles, in a manner structurally mimicking spikes on a native virus. Here we report the development of Newcastle disease virus-like particles (NDVLPs) displaying the prefusion-stabilized SARS-CoV-2 spike ectodomain (S2P). Immunoassays with SARS-CoV-2-neutralizing antibodies revealed the antigenicity of S2P-NDVLP to be generally similar to that of soluble S2P, and negative-stain electron microscopy showed S2P on the NDVLP surface to be displayed with a morphology corresponding to its prefusion conformation. Mice immunized with S2P-NDVLP showed substantial neutralization titers (geometric mean ID50 = 386) two weeks after prime immunization, significantly higher than those elicited by a molar equivalent amount of soluble S2P (geometric mean ID50 = 17). Neutralizing titers at Week 5, two weeks after a boost immunization with S2P-NDVLP doses ranging from 2.0 to 250 μg, extended from 2125 to 4552, and these generally showed a higher ratio of neutralization versus ELISA than observed with soluble S2P. Overall, S2P-NDVLP appears to be a promising COVID-19 vaccine candidate capable of eliciting substantial neutralizing activity.

A platform incorporating trimeric antigens into self-assembling nanoparticles reveals SARS-CoV-2-spike nanoparticles to elicit substantially higher neutralizing responses than spike alone

Antigens displayed on self-assembling nanoparticles can stimulate strong immune responses and have been playing an increasingly prominent role in structure-based vaccines. However, the development of such immunogens is often complicated by inefficiencies in their production. To alleviate this issue, we developed a plug-and-play platform using the spontaneous isopeptide-bond formation of the SpyTag:SpyCatcher system to display trimeric antigens on self-assembling nanoparticles, including the 60-subunit Aquifex aeolicus lumazine synthase (LuS) and the 24-subunit Helicobacter pylori ferritin. LuS and ferritin coupled to SpyTag expressed well in a mammalian expression system when an N-linked glycan was added to the nanoparticle surface. The respiratory syncytial virus fusion (F) glycoprotein trimer-stabilized in the prefusion conformation and fused with SpyCatcher-could be efficiently conjugated to LuS-SpyTag or ferritin-SpyTag, enabling multivalent display of F trimers with prefusion antigenicity. Similarly, F-glycoprotein trimers from human parainfluenza virus-type 3 and spike-glycoprotein trimers from SARS-CoV-2 could be displayed on LuS nanoparticles with decent yield and antigenicity. Notably, murine vaccination with 0.08 µg of SARS-CoV-2 spike-LuS nanoparticle elicited similar neutralizing responses as 2.0 µg of spike, which was ~ 25-fold higher on a weight-per-weight basis. The versatile platform described here thus allows for multivalent plug-and-play presentation on self-assembling nanoparticles of trimeric viral antigens, with SARS-CoV-2 spike-LuS nanoparticles inducing particularly potent neutralizing responses.

Evaluation of the mRNA-1273 Vaccine against SARS-CoV-2 in Nonhuman Primates

BACKGROUND

Vaccines to prevent coronavirus disease 2019 (Covid-19) are urgently needed. The effect of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines on viral replication in both upper and lower airways is important to evaluate in nonhuman primates.

METHODS

Nonhuman primates received 10 or 100 μg of mRNA-1273, a vaccine encoding the prefusion-stabilized spike protein of SARS-CoV-2, or no vaccine. Antibody and T-cell responses were assessed before upper- and lower-airway challenge with SARS-CoV-2. Active viral replication and viral genomes in bronchoalveolar-lavage (BAL) fluid and nasal swab specimens were assessed by polymerase chain reaction, and histopathological analysis and viral quantification were performed on lung-tissue specimens.

RESULTS

The mRNA-1273 vaccine candidate induced antibody levels exceeding those in human convalescent-phase serum, with live-virus reciprocal 50% inhibitory dilution (ID50) geometric mean titers of 501 in the 10-μg dose group and 3481 in the 100-μg dose group. Vaccination induced type 1 helper T-cell (Th1)-biased CD4 T-cell responses and low or undetectable Th2 or CD8 T-cell responses. Viral replication was not detectable in BAL fluid by day 2 after challenge in seven of eight animals in both vaccinated groups. No viral replication was detectable in the nose of any of the eight animals in the 100-μg dose group by day 2 after challenge, and limited inflammation or detectable viral genome or antigen was noted in lungs of animals in either vaccine group.

CONCLUSIONS

Vaccination of nonhuman primates with mRNA-1273 induced robust SARS-CoV-2 neutralizing activity, rapid protection in the upper and lower airways, and no pathologic changes in the lung. (Funded by the National Institutes of Health and others.).

From patent to patient: analysing access to innovative cancer drugs

Analysis of cancer drugs licensed through the European Medicines Agency (EMA) in 2000-2016 shows that the number of authorisations increased over that timeframe. The median number of licensed drugs each year rose from six for 2000-2008 to 13.5 for 2009-2016. Over 2000-2016, there were 64 drug authorisations for haematological, 15 for breast, and 12 for skin cancer, but none for oesophageal, brain, bladder, or uterine cancer. Only 6% of authorisations included a paediatric indication. The average time for a drug to progress from patent priority date to availability on the National Health Service (NHS) increased from 12.8 years for drugs first licensed in 2000-2008 to 14.0 years for those licensed in 2009-2016. There was evidence that the most innovative drugs were not being prioritised for EMA licensing and NICE approval.

A Platform Incorporating Trimeric Antigens into Self-Assembling Nanoparticles Reveals SARS-CoV-2-Spike Nanoparticles to Elicit Substantially Higher Neutralizing Responses than Spike Alone

Antigens displayed on self-assembling nanoparticles can stimulate strong immune responses and have been playing an increasingly prominent role in structure-based vaccines. However, the development of such immunogens is often complicated by inefficiencies in their production. To alleviate this issue, we developed a plug-and-play platform using the spontaneous isopeptide-bond formation of the SpyTag:SpyCatcher system to display trimeric antigens on self-assembling nanoparticles, including the 60-subunit Aquifex aeolicus lumazine synthase (LuS) and the 24-subunit Helicobacter pylori ferritin. LuS and ferritin coupled to SpyTag expressed well in a mammalian expression system when an N-linked glycan was added to the nanoparticle surface. The respiratory syncytial virus fusion (F) glycoprotein trimer - stabilized in the prefusion conformation and fused with SpyCatcher - could be efficiently conjugated to LuS-SpyTag or ferritin-SpyTag, enabling multivalent display of F trimers with prefusion antigenicity. Similarly, F-glycoprotein trimers from human parainfluenza virus-type 3 and spike-glycoprotein trimers from SARS-CoV-2 could be displayed on LuS nanoparticles with decent yield and antigenicity. Notably, murine vaccination with the SARS-CoV-2 spike-LuS nanoparticles elicited ~25-fold higher neutralizing responses, weight-per-weight relative to spike alone. The versatile platform described here thus allows for multivalent plug-and-play presentation on self-assembling nanoparticles of trimeric viral antigens, with SARS-CoV-2 spike-LuS nanoparticles inducing particularly potent neutralizing responses.

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 > 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 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 (>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 >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>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.