ATR inhibitor, camonsertib, dose optimization in patients with biomarker-selected advanced solid tumors (TRESR study)

BACKGROUND

Camonsertib is a selective oral inhibitor of ataxia telangiectasia and Rad3-related (ATR) kinase with demonstrated efficacy in tumors with DNA damage response gene deficiencies. On-target anemia is the main drug-related toxicity typically manifesting after the period of dose-limiting toxicity evaluation. Thus dose/schedule optimization requires extended follow-up to assess prolonged treatment effects.

METHODS

Long-term safety/tolerability and antitumor efficacy of three camonsertib monotherapy dose levels/schedules were assessed in the TRESR study dose-optimization phase: 160 mg once daily (QD) 3 days on/4 off (160 3/4; the preliminary recommended phase II dose [RP2D]) and two step-down groups of 120 mg QD 3/4 (120 3/4) and 160 mg QD 3/4, 2 weeks on/1 off (160 3/4, 2/1w). Safety endpoints included incidence of treatment-related adverse events (TRAEs), dose modifications, and transfusions. Efficacy endpoints included overall response rate, clinical benefit rate, progression-free survival, and circulating-tumor-DNA (ctDNA)-based molecular response rate.

RESULTS

The analysis included 119 patients: 160 3/4 (n = 67), 120 3/4 (n = 25), and 160 3/4, 2/1w (n = 27) treated up to 117.1 weeks as of the data cutoff. The risk of developing grade 3 anemia was significantly lower in the 160 3/4, 2/1w group compared with the preliminary RP2D group (HR = 0.23, 2-sided P = .02), translating to reduced transfusion and dose reduction requirements. The intermittent weekly schedule did not compromise antitumor activity.

CONCLUSION

The 160 3/4, 2/1w dose was established as an optimized regimen for future camonsertib monotherapy studies offering significantly reduced anemia incidence without any compromise to efficacy.

Treatment Patterns and Clinical Outcomes Among Patients With Metastatic Prostate Cancer Harboring Homologous Recombination Repair Mutations

BACKGROUND

There is currently limited literature assessing the real-world treatment patterns and clinical outcomes of patients with metastatic castration-resistant prostate cancer (mCRPC) and homologous recombination repair (HRR) mutations.

METHODS

Medical charts were abstracted for mCRPC patients with ≥ 1 of 12 HRR somatic gene alterations treated at US oncology centers participating in the American Association for Cancer Research Project Genomics Evidence Neoplasia Information Exchange. Treatment patterns and clinical outcomes were assessed from the initiation of first-line or later (1L+) mCRPC therapy received on or after July 1, 2014.

RESULTS

Among 138 patients included in the study, the most common somatic HRR mutations were CDK12 (47.8%), BRCA2 (22.5%), and ATM (21.0%). Novel hormonal therapy and taxane chemotherapy were most commonly used in 1L; taxane use increased in later lines. Median overall survival (95% confidence interval [CI]) was 36.3 (30.7-47.8) months from initiation of 1L therapy and decreased for subsequent lines. Similarly, there was a trend of decreasing progression-free survival and prostate-specific antigen response from 1L to 4L+ therapy.

CONCLUSIONS

Treatment patterns identified in this study were similar to those among patients with mCRPC regardless of tumor HRR mutation status in the literature.

Development of a Practical Nomogram for Personalized Anemia Management in Patients Treated with Ataxia Telangiectasia and Rad3-related Inhibitor Camonsertib

PURPOSE

Camonsertib is a highly selective and potent inhibitor of ataxia telangiectasia and Rad3-related (ATR) kinase. Dose-dependent anemia is a class-related on-target adverse event often requiring dose modifications. Individual patient risk factors for the development of significant anemia complicate the selection of a "one-size-fits-all" ATR inhibitor (ATRi) dose and schedule, possibly leading to suboptimal therapeutic doses in patients at low risk of anemia. We evaluated whether early predictors of anemia could be identified to ultimately inform a personalized dose-modification approach.

PATIENTS AND METHODS

On the basis of preclinical observations and a mechanistic understanding of ATRi-related anemia, we identified several potential factors to explore in a multivariable linear regression modeling tool for predicting hemoglobin level ahead of day 22 (cycle 2) of treatment.

RESULTS

In patients treated with camonsertib monotherapy (NCT04497116), we observed that hemoglobin decline is consistently preceded by reticulocytopenia, and dose- and exposure-dependent decreases in monocytes. We developed a nomogram incorporating baseline and day 8 hemoglobin and reticulocyte values that predicted the day 22 hemoglobin values of patients with clinically valuable concordance (within 7.5% of observations) 80% of the time in a cross-validation performance test of data from 60 patients.

CONCLUSIONS

The prediction of future hemoglobin decrease, after a week of treatment, may enable a personalized, early dose modification to prevent development of clinically significant anemia and resulting unscheduled dose holds or transfusions.

Combination of Itacitinib or Parsaclisib with Pembrolizumab in Patients with Advanced Solid Tumors: A Phase I Study

PURPOSE

This phase Ib open-label, multicenter, platform study (NCT02646748) explored safety, tolerability, and preliminary activity of itacitinib (Janus kinase 1 inhibitor) or parsaclisib (phosphatidylinositol 3-kinase δ inhibitor) in combination with pembrolizumab [programmed death-1 (PD-1) inhibitor].

EXPERIMENTAL DESIGN

Patients with advanced or metastatic solid tumors with disease progression following all available therapies were enrolled and received itacitinib (Part 1 initially 300 mg once daily) or parsaclisib (Part 1 initially 10 mg once daily; Part 2 all patients 0.3 mg once daily) plus pembrolizumab (200 mg every 3 weeks).

RESULTS

A total of 159 patients were enrolled in the study and treated with itacitinib (Part 1, n = 49) or parsaclisib (Part 1, n = 83; Part 2, n = 27) plus pembrolizumab. The maximum tolerated/pharmacologically active doses were itacitinib 300 mg once daily and parsaclisib 30 mg once daily. Most common itacitinib treatment-related adverse events (TRAE) were fatigue, nausea, and anemia. Most common parsaclisib TRAEs were fatigue, nausea, diarrhea, and pyrexia in Part 1, and fatigue, maculopapular rash, diarrhea, nausea, and pruritus in Part 2. In patients receiving itacitinib plus pembrolizumab, four (8.2%) achieved a partial response (PR) in Part 1. Among patients receiving parsaclisib plus pembrolizumab, 5 (6.0%) achieved a complete response and 9 (10.8%) a PR in Part 1; 5 of 27 (18.5%) patients in Part 2 achieved a PR.

CONCLUSIONS

Although combination of itacitinib or parsaclisib with pembrolizumab showed modest clinical activity in this study, the overall response rates observed did not support continued development in patients with solid tumors.

SIGNIFICANCE

PD-1 blockade combined with targeted therapies have demonstrated encouraging preclinical activity. In this phase I study, patients with advanced solid tumors treated with pembrolizumab (PD-1 inhibitor) and either itacitinib (JAK1 inhibitor) or parsaclisib (PI3Kδ inhibitor) experienced limited clinical activity beyond that expected with checkpoint inhibition alone and showed little effect on T-cell infiltration in the tumor. These results do not support continued development of these combinations.

Exploratory analysis of mesenteric-portal axis CT radiomic features for survival prediction of patients with pancreatic ductal adenocarcinoma

OBJECTIVE

To develop and evaluate task-based radiomic features extracted from the mesenteric-portal axis for prediction of survival and response to neoadjuvant therapy in patients with pancreatic ductal adenocarcinoma (PDAC).

METHODS

Consecutive patients with PDAC who underwent surgery after neoadjuvant therapy from two academic hospitals between December 2012 and June 2018 were retrospectively included. Two radiologists performed a volumetric segmentation of PDAC and mesenteric-portal axis (MPA) using a segmentation software on CT scans before (CTtp0) and after (CTtp1) neoadjuvant therapy. Segmentation masks were resampled into uniform 0.625-mm voxels to develop task-based morphologic features (n = 57). These features aimed to assess MPA shape, MPA narrowing, changes in shape and diameter between CTtp0 and CTtp1, and length of MPA segment affected by the tumor. A Kaplan-Meier curve was generated to estimate the survival function. To identify reliable radiomic features associated with survival, a Cox proportional hazards model was used. Features with an ICC  ≥ 0.80 were used as candidate variables, with clinical features included a priori.

RESULTS

In total, 107 patients (60 men) were included. The median survival time was 895 days (95% CI: 717, 1061). Three task-based shape radiomic features (Eccentricity mean tp0, Area minimum value tp1, and Ratio 2 minor tp1) were selected. The model showed an integrated AUC of 0.72 for prediction of survival. The hazard ratio for the Area minimum value tp1 feature was 1.78 (p = 0.02) and 0.48 for the Ratio 2 minor tp1 feature (p = 0.002).

CONCLUSION

Preliminary results suggest that task-based shape radiomic features can predict survival in PDAC patients.

KEY POINTS

• In a retrospective study of 107 patients who underwent neoadjuvant therapy followed by surgery for PDAC, task-based shape radiomic features were extracted and analyzed from the mesenteric-portal axis. • A Cox proportional hazards model that included three selected radiomic features plus clinical information showed an integrated AUC of 0.72 for prediction of survival, and a better fit compared to the model with only clinical information.

Camonsertib in DNA damage response-deficient advanced solid tumors: phase 1 trial results

Predictive biomarkers of response are essential to effectively guide targeted cancer treatment. Ataxia telangiectasia and Rad3-related kinase inhibitors (ATRi) have been shown to be synthetic lethal with loss of function (LOF) of ataxia telangiectasia-mutated (ATM) kinase, and preclinical studies have identified ATRi-sensitizing alterations in other DNA damage response (DDR) genes. Here we report the results from module 1 of an ongoing phase 1 trial of the ATRi camonsertib (RP-3500) in 120 patients with advanced solid tumors harboring LOF alterations in DDR genes, predicted by chemogenomic CRISPR screens to sensitize tumors to ATRi. Primary objectives were to determine safety and propose a recommended phase 2 dose (RP2D). Secondary objectives were to assess preliminary anti-tumor activity, to characterize camonsertib pharmacokinetics and relationship with pharmacodynamic biomarkers and to evaluate methods for detecting ATRi-sensitizing biomarkers. Camonsertib was well tolerated; anemia was the most common drug-related toxicity (32% grade 3). Preliminary RP2D was 160 mg weekly on days 1-3. Overall clinical response, clinical benefit and molecular response rates across tumor and molecular subtypes in patients who received biologically effective doses of camonsertib (>100 mg d-1) were 13% (13/99), 43% (43/99) and 43% (27/63), respectively. Clinical benefit was highest in ovarian cancer, in tumors with biallelic LOF alterations and in patients with molecular responses. ClinicalTrials.gov registration: NCT04497116 .

Phase 1/2 study of epacadostat in combination with durvalumab in patients with metastatic solid tumors

BACKGROUND

Targeting programmed cell death protein 1 (PD-1) and indoleamine 2,3-dioxygenase (IDO1) pathways is an appealing option for cancer treatment.

METHODS

The open-label, phase 1/2 ECHO-203 study evaluated the safety, tolerability, and efficacy of the IDO1 inhibitor epacadostat in combination with durvalumab, a human anti-PD-L1 monoclonal antibody in adult patients with advanced solid tumors.

RESULTS

The most common treatment-related adverse events were fatigue (30.7%), nausea (21.0%), decreased appetite (13.1%), pruritus (12.5%), maculopapular rash (10.8%), and diarrhea (10.2%). Objective response rate (ORR) in the overall phase 2 population was 12.0%. Higher ORR was observed in immune checkpoint inhibitor (CPI)-naïve patients (16.1%) compared with patients who had received previous CPI (4.1%). Epacadostat pharmacodynamics were evaluated by comparing baseline kynurenine levels with those on therapy at various time points. Only the 300-mg epacadostat dose showed evidence of kynurenine modulation, albeit unsustained.

CONCLUSIONS

Epacadostat plus durvalumab was generally well tolerated in patients with advanced solid tumors. ORR was low, and evaluation of kynurenine concentration from baseline to cycle 2, day 1, and cycle 5, day 1, suggested >300 mg epacadostat twice daily is needed to ensure sufficient drug effect.

CLINICAL TRIAL INFORMATION

A study of epacadostat (INCB024360) in combination with durvalumab (MEDI4736) in subjects with selected advanced solid tumors (ECHO-203) (NCT02318277).

Genomic analysis of early-stage lung cancer reveals a role for TP53 mutations in distant metastasis

Patients with non-small cell lung cancer (NSCLC) who have distant metastases have a poor prognosis. To determine which genomic factors of the primary tumor are associated with metastasis, we analyzed data from 759 patients originally diagnosed with stage I-III NSCLC as part of the AACR Project GENIE Biopharma Collaborative consortium. We found that TP53 mutations were significantly associated with the development of new distant metastases. TP53 mutations were also more prevalent in patients with a history of smoking, suggesting that these patients may be at increased risk for distant metastasis. Our results suggest that additional investigation of the optimal management of patients with early-stage NSCLC harboring TP53 mutations at diagnosis is warranted in light of their higher likelihood of developing new distant metastases.

Safety and efficacy of etigilimab in combination with nivolumab in select recurrent/advanced solid tumors

2651

Background: Etigilimab (etig), a humanized IgG1 monoclonal antibody, blocks TIGIT interaction with PVR (poliovirus receptor) and inhibits downstream signalling with target cell killing. Etig +/- nivolumab (nivo) showed acceptable safety and preliminary activity in a FIH Phase 1a/b study in solid tumors. ACTIVATE, an open-label Phase 1b/2 basket study is evaluating further efficacy, safety, tolerability and PK/PD of etig+nivo. This is a preliminary efficacy and safety analysis from ACTIVATE. Methods: Subjects with advanced/metastatic solid tumors without curative/standard of care therapies are given IV etig+nivo Q2W until disease progression or intolerable toxicity. Six open cohorts are enrolling in parallel: endometrial cancer (post-front-line platinum), endometrial cancer (2-3 prior lines), PD-L1+ checkpoint-inhibitor-naïve (CPI-n) cervical cancer, rare cancers (germ cell tumor (GCT), sarcoma, uveal melanoma), ovarian cancer (post-front-line platinum) and TMB-h/MSS, (TMB >10mut/mb) tumors. Tumor assessments are done every 8 weeks following baseline scan. Primary endpoint is investigator-assessed ORR by RECIST 1.1. Secondary endpoints include duration of response and safety. Results: Of 27 efficacy-evaluable subjects enrolled in the 6 open cohorts with minimum 1 staging scan or radiological/clinical progression at data cut-off of 02/10/22, 12 had clinical benefit with 1 complete response (CR), 2 partial responses (PRs) and 9 stable diseases (SDs) and 15 had radiological/clinical progressive disease (PD), with an overall response rate (ORR) of 11% and disease control rate (DCR) of 44%. Conclusions: Etig+nivo is safe and well tolerated with no new safety signals. Early efficacy was noted in cervical cancer (1CR, 1PR and 1SD) and uveal melanoma (3 SDs >20 weeks). Encouraging activity was also noted in ovarian cancer and post-CPI treated TMB-H/MSS NSCLC. These early data support continued evaluation of the combination of etig+nivo. Clinical activity was notable as below. Clinical trial information: NCT04761198. [Table: see text]

Circulating tumor DNA (ctDNA) determinants of improved outcomes in patients (pts) with advanced solid tumors receiving the ataxia telangiectasia and Rad3-related inhibitor (ATRi), RP-3500, in the phase 1/2a TRESR trial (NCT04497116)

3082

Background: RP-3500 is a selective and potent oral ATRi in development for advanced solid tumors harboring loss-of-function (LOF) alterations in genes associated with ATRi sensitivity. We determined whether ctDNA can facilitate enrollment/monitoring of pts treated with RP-3500. Methods: Serial plasma samples collected at baseline (BL, 99 pts) and early timepoints on therapy (89 pts, 3-9 weeks [wks]) were profiled for ctDNA (Tempus xF or Guardant360). Targeted next generation sequencing (NGS) (SNiPDx panel) was performed on matched peripheral blood mononuclear cells and tumor samples collected at BL. Molecular ctDNA response (MR) was defined as ≥50% reduction in mean variant allele frequency (VAF) from BL to any timepoint ≤9 wks on-therapy. Clonal hematopoiesis (CH) or germline alterations were excluded from the analysis. Efficacy was assessed in pts treated with > 100 mg RP-3500/day with ≥1 post-BL response assessment. Endpoints included progression-free survival (PFS) and clinical benefit rate (CBR; CR/PR by RECIST1.1 or PSA/CA-125, or > 16 wks on treatment). Results: BL ctDNA was detected in 82% (81/99) of pts. Eligibility alterations were evaluable by the ctDNA panel in 61% (60/99) of pts, excluding structural/copy number variants and genes/exons not on the panel. Percent agreement between BL ctDNA and local eligibility NGS test was 93% (56/60). CH variants were identified in 26 pts (1-14 per pt); median VAF was 0.4% (0.1-12.4%). Two pts with pathogenic ataxia-telangiectasia mutated ( ATM) alterations were determined to be from CH. MRs were observed in 44% (24/55) of pts with median time to MR of 3.3 wks and were across tumors harboring ATM (10/20), BRCA2 (7/10), BRCA1 (4/15), CDK12 (1/3), PALB2 (1/3) and RAD51C (1/1) pathogenic alterations. Four pts with BRCA1 mutant tumors had MRs, 2 of whom (breast cancer) had received prior PARPi and had confirmed BRCA1 reversion mutations and clinical benefit (CB). One pt with g ATM pancreatic cancer with CB had > 90% reduction in KRAS mutant VAF at 3 wks. MR was associated with longer mPFS (29 vs 12 wks, p = 0.0002) and significantly higher CBR (17/22 (77%) vs. 8/28 (29%); p = 0.001) than those without MR. Pts with MRs not achieving CB (N = 5) included 4 with RP-3500 dose interruptions/reductions and 1 who discontinued early (10 wks) due to clinical progression but with decreased target lesions and stable disease. Conclusions: ctDNA testing is a reliable method to detect DNA damage repair LOF alterations but is limited to alterations and genes/exons covered by the ctDNA test. CH alterations are frequent, especially for ATM, thus matched normal analysis is preferred. Changes in ctDNA as early as 3 wks were associated with improved outcomes and may be useful for evaluating drug activity in heterogenous tumors outside of traditional efficacy endpoints. Clinical trial information: NCT04497116.

A phase 1b/2, dose-escalation, randomized, multicenter study of maintenance (maint) ivaltinostat (ival) plus capecitabine (cap) or capecitabine monotherapy in patients (pts) with metastatic pancreatic adenocarcinoma (PDAC) whose disease has not progressed on first-line FOLFIRINOX chemotherapy (CT)

TPS4181

Background: The mainstay of treatment (TX) for pts with advanced or mPDAC consists of CT, with FOLFIRINOX and gemcitabine (gem)/nab-paclitaxel currently representing the front-line standards of care. TX is generally continued until either dis progression (progr) or cumulative toxicity, with pts often reaching a plateau in response after 4-6 mos. For those who have achieved dis control (stable dis or better) on front-line CT, a maint TX strategy that can effectively delay dis progr while preserving quality of life with minimal cumulative toxicity is highly desirable. However, aside from PARP inhibition in the subset of PDAC pts with gBRCA mutated dis, there is no current standard of care in this maint setting. Ival is a pan-HDAC (histone deacetylation) inhibitor that increases histone acetylation (HA), suppresses PDAC cell proliferation, and promotes apoptosis in PDAC cell lines in a dose-dependent manner. It has demonstrated synergy with 5-FU in cholangiocarcinoma cell lines and shows promising antitumor activity when combined with cap in syngeneic PDAC mouse models. On these bases, we are conducting a ph1b/randomized ph2 trial of ival plus cap vs cap alone in the maint setting for pts with mPDAC who have not progressed on front-line FOLFIRINOX. Methods: Key eligibility criteria include pts with mPDAC; no evidence of dis progr following at least 16 wks of front-line FOLFIRINOX at full or modified doses; ECOG PS 0-1; and no known gBRCA1/2 mutation. The study includes an initial dose-esc ph1b evaluating 3 dose levels of ival, (60, 125, and 250mg/m2 iv weekly on days 1 and 8) in combination (comb) with cap (1000mg/m2 po BID on days 1-14) of a 21-day cycle, using a standard 3 + 3 dose-esc design. Of note, ival 250 mg/m2 represents the RP2D identified in prior clinical studies of this agent both as monotherapy in solid tumors and in comb with gem/erlotinib in advanced PDAC pts. In the ph2 portion, pts will be randomized 1:1 to receive either ival plus cap or cap alone, in 21-day cycles, until dis progr, with tumor assessments occurring at 6-wk intervals. Blood will be collected at pre-specified serial timepoints for pharmacodynamic assessments, including HA of PBMCs. Primary endpoint for ph2 is investigator-adjudicated PFS. The primary analysis will compare PFS distributions in the ival/cap and cap alone arms using a one-sided log rank test with an alpha = 0.10. The assumed true 6-mo PFS rates are 35% (cap), based on historic data, and 60% (ival/cap), which corresponds to an HR of 0.487. Assuming an accrual duration of 18 mos and a dropout/lost to follow-up rate of 10%, the estimated total number of pts in the randomized ph2 portion is 52 (26 per arm). Enrollment is expected to being in spring 2022 across 25 U.S. sites.

Trial in progress: Phase I study of SY-5609, a potent, selective CDK7 inhibitor, with initial expansion in adults with metastatic pancreatic cancer

TPS4180

Background: SY-5609 is an oral, selective, potent CDK7 inhibitor that targets two fundamental processes in cancer: transcription and cell cycle control. Early results from the Phase 1 dose escalation portion in patients (pts) with advanced solid tumors reported improved tolerability of the intermittent 7 days on followed by 7 days off (7/7) schedule with ongoing dose escalation beyond the continuous daily dosing maximum tolerated dose. Single-agent clinical activity was demonstrated with durable stable disease, target lesion regressions, and reduction in tumor markers observed in multiple tumor types, notably in pancreatic cancer with a disease control rate (DCR) of 38.5% (Sharma 2021). Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate of 11% (ACS Cancer Facts and figures, 2022) with limited treatment options and therefore, is a disease in need of novel effective therapies. Oncogenic KRAS mutations are prevalent in PDAC. Mutant KRAS is a potent stimulator of mitogenic MAPK signaling and downstream transcriptional programs for cell proliferation. Preclinical studies have shown that CDK7 inhibition via SY-5609 inhibits tumor growth in KRAS mutant PDAC xenograft models, in many cases leading to regressions. SY-5609 also potentiates gemcitabine (gem) activity in PDAC cells in vitro and in xenografts in vivo (Henry 2021). Therefore, combining SY-5609 with gem +/- nab-paclitaxel (nab-pac) offers a potential new treatment strategy for metastatic PDAC (mPDAC). The expansion portion of this Phase 1 study will evaluate SY-5609 in combination with gem +/- nab-pac in mPDAC pts. Gem +/- nab-pac will be administered on a biweekly schedule as it has shown better tolerability and similar clinical activity compared to the standard of care (SOC) administration schedule (Rehman 2020). Methods: This is an ongoing Phase 1, multi-center study in select solid tumors, amended to open expansion cohorts for mPDAC and expected to enroll approximately 80 mPDAC pts who have progressed on SOC treatments. Objectives of the expansion cohorts include evaluation of safety and efficacy of SY-5609 in combination with gem +/- nab-pac. Key objectives of the two parallel safety lead-in cohorts 1) SY-5609 + gem and 2) SY-5609 + gem + nab-pac are safety and determination of the recommended combination dose of the doublet and triplet for subsequent cohort expansions using a 3+3 escalation design. Key objectives of expansion cohorts are to describe efficacy, defined by progression-free survival, overall response rate, and DCR. Additional objectives include evaluation of pharmacokinetics and pharmacodynamics of SY-5609 in combination with gem +/- nab-pac. SY-5609 will be administered orally once daily on a 7/7 regimen and gem +/- nab-pac will be administered intravenously, in a 4-week cycle. The expansion portion is now open to enrollment. Clinical trial information: NCT04247126.

A two-part, phase II, multi-center study of the ERK inhibitor ulixertinib (BVD-523) for patients with advanced malignancies harboring MEK or atypical BRAF alterations (BVD-523-ABC)

TPS3172

Background: Ulixertinib (BVD-523) is a small molecule inhibitor of extracellular signal-regulated kinases 1/2 (ERK1/2) in development as a novel anti-cancer drug. Early clinical data demonstrated anti-tumor activity, especially for patients with tumors harboring atypical BRAF or MEK1/2 alterations (Sullivan et al., Cancer Discov. 2018;8(2):184-195). Atypical BRAF (non-V600) alterations can be categorized according to characteristics of molecular signaling (Class II or III), are seen in approximately 3% of all human cancers, and there are currently no approved therapies for this indication. Similar to atypical BRAF alterations, the incidence of MEK1/2 alterations are rare in human tumors (< 1 %). Preclinical data have demonstrated activity of ulixertinib in MEK mutant models. Ulixertinib has FDA fast-track designation for patients with solid tumors, other than CRC, with specific BRAF mutations (G469A, L485W, or L597Q). Designed with intent to register, the BVD-523-ABC clinical trial will continue evaluation of ulixertinib in patients with tumors harboring any atypical BRAF or MEK1/2 alteration (NCT04488003). Methods: This multi-center, phase II study, will be conducted in two parts and assess the clinical benefit, safety, pharmacokinetics, and pharmacodynamics of ulixertinib in patients with advanced malignancies. Ulixertinib will be administered at the RP2D of 600 mg BID for 28-day treatment cycles. Eligible patients will have locally advanced or metastatic cancer which progressed following standard systemic therapies, or for which the patient is not a candidate or refused systemic therapy. Planned correlative analyses include reverse phase protein array and transcriptomics of tumor tissue. Part A is open-label and tumor agnostic, except for group 4 and 6 (CRC patients only). Patients will enroll into one of six groups based on BRAF (groups 1-4) or MEK1/2 (groups 5-6) tumor alteration (38 patients per group). Overall response rate (ORR) is the primary endpoint for Part A, with secondary endpoints including duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Part B is tumor histology specific. Patients will be randomized to receive either ulixertinib or physician's choice of treatment in a 2:1 ratio. Up to three specified tumor histologies will be defined, guided by available Part A data (n = 80-100 per histology). The primary endpoint of Part B is PFS, and secondary endpoints include OS, ORR, and DOR. This study has enrolled 43 patients of the planned 228 in Part A at the time of abstract submission. Clinical trial information: NCT04488003.

Assessment of Capecitabine and Bevacizumab With or Without Atezolizumab for the Treatment of Refractory Metastatic Colorectal Cancer: A Randomized Clinical Trial

IMPORTANCE

Cotargeting vascular endothelial growth factor and programmed cell death 1 or programmed cell death ligand 1 may produce anticancer activity in refractory metastatic colorectal cancer (mCRC). The clinical benefit of atezolizumab combined with chemotherapy and bevacizumab remains unclear for the treatment of mCRC.

OBJECTIVES

To assess whether the addition of atezolizumab to capecitabine and bevacizumab therapy improves progression-free survival (PFS) among patients with refractory mCRC and to perform exploratory analyses among patients with microsatellite-stable (MSS) disease and liver metastasis.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind phase 2 randomized clinical trial enrolled 133 patients between September 25, 2017, and June 28, 2018 (median duration of follow-up for PFS, 20.9 months), with data cutoff on May 4, 2020. The study was conducted at multiple centers through the Academic and Community Cancer Research United network. Adult patients with mCRC who experienced disease progression while receiving fluoropyrimidine, oxaliplatin, irinotecan, bevacizumab, and anti-epidermal growth factor receptor antibody therapy (if the patient had a RAS wild-type tumor) were included.

INTERVENTIONS

Patients were randomized (2:1) to receive capecitabine (850 or 1000 mg/m2) twice daily on days 1 to 14 and bevacizumab (7.5 mg/kg) on day 1 plus either atezolizumab (1200 mg; investigational group) or placebo (placebo group) on day 1 of each 21-day cycle.

MAIN OUTCOMES AND MEASURES

The primary end point was PFS; 110 events were required to detect a hazard ratio (HR) of 0.65 with 80% power (1-sided α = .10). Secondary end points were objective response rate, overall survival (OS), and toxic effects.

RESULTS

Of 133 randomized patients, 128 individuals (median age, 58.0 years [IQR, 51.0-65.0 years]; 77 men [60.2%]) were assessed for efficacy (82 in the investigational group and 46 in the placebo group). Overall, 15 patients (11.7%) self-identified as African American or Black, 8 (6.3%) as Asian, 1 (0.8%) as Pacific Islander, 101 (78.9%) as White, 1 (0.8%) as multiple races (Asian, Native Hawaiian/Pacific Islander, and White), and 2 (1.6%) as unknown race or unsure of race. Microsatellite-stable disease was present in 110 patients (69 in the investigational group and 41 in the placebo group). Median PFS was 4.4 months (95% CI, 4.1-6.4 months) in the investigational group and 3.6 months (95% CI, 2.2-6.2 months) in the placebo group (1-sided log-rank P = .07, a statistically significant result; HR, 0.75; 95% CI, 0.52-1.09). Among patients with MSS and proficient mismatch repair, the HR for PFS was 0.66 (95% CI, 0.44-0.99). The most common grade 3 or higher treatment-related adverse events in the investigational vs placebo groups were hypertension (6 patients [7.0%] vs 2 patients [4.3%]), diarrhea (6 patients [7.0%] vs 2 patients [4.3%]), and hand-foot syndrome (6 patients [7.0%] vs 2 patients [4.3%]). One treatment-related death occurred in the investigational group. In the investigational group, the response rate was higher among patients without liver metastasis (3 of 13 individuals [23.1%]) vs with liver metastasis (4 of 69 individuals [5.8%]). The benefit of atezolizumab for PFS and OS was greater among patients without vs with liver metastasis (primary analysis of PFS: HR, 0.63 [95% CI, 0.27-1.47] vs 0.77 [95% CI, 0.51-1.17]; OS: HR, 0.33 [95% CI, 0.11-1.02] vs 1.14 [95% CI, 0.72-1.81]).

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, the addition of atezolizumab to capecitabine and bevacizumab therapy provided limited (ie, not clinically meaningful) clinical benefit. Patients with MSS and proficient mismatch repair tumors and those without liver metastasis benefited more from dual inhibition of the vascular endothelial growth factor and programmed cell death 1 or programmed cell death ligand 1 pathways.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02873195.

CT Radiomic Features of Superior Mesenteric Artery Involvement in Pancreatic Ductal Adenocarcinoma: A Pilot Study

Background Current imaging methods for prediction of complete margin resection (R0) in patients with pancreatic ductal adenocarcinoma (PDAC) are not reliable. Purpose To investigate whether tumor-related and perivascular CT radiomic features improve preoperative assessment of arterial involvement in patients with surgically proven PDAC. Materials and Methods This retrospective study included consecutive patients with PDAC who underwent surgery after preoperative CT between 2012 and 2019. A three-dimensional segmentation of PDAC and perivascular tissue surrounding the superior mesenteric artery (SMA) was performed on preoperative CT images with radiomic features extracted to characterize morphology, intensity, texture, and task-based spatial information. The reference standard was the pathologic SMA margin status of the surgical sample: SMA involved (tumor cells ≤1 mm from margin) versus SMA not involved (tumor cells >1 mm from margin). The preoperative assessment of SMA involvement by a fellowship-trained radiologist in multidisciplinary consensus was the comparison. High reproducibility (intraclass correlation coefficient, 0.7) and the Kolmogorov-Smirnov test were used to select features included in the logistic regression model. Results A total of 194 patients (median age, 66 years; interquartile range, 60-71 years; age range, 36-85 years; 99 men) were evaluated. Aside from surgery, 148 patients underwent neoadjuvant therapy. A total of 141 patients' samples did not involve SMA, whereas 53 involved SMA. A total of 1695 CT radiomic features were extracted. The model with five features (maximum hugging angle, maximum diameter, logarithm robust mean absolute deviation, minimum distance, square gray level co-occurrence matrix correlation) showed a better performance compared with the radiologist assessment (model vs radiologist area under the curve, 0.71 [95% CI: 0.62, 0.79] vs 0.54 [95% CI: 0.50, 0.59]; P < .001). The model showed a sensitivity of 62% (33 of 53 patients) (95% CI: 51, 77) and a specificity of 77% (108 of 141 patients) (95% CI: 60, 84). Conclusion A model based on tumor-related and perivascular CT radiomic features improved the detection of superior mesenteric artery involvement in patients with pancreatic ductal adenocarcinoma. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Do and Kambadakone in this issue.

Abstract CC04-01: First-in-human biomarker-driven phase I TRESR trial of ataxia telangiectasia and Rad3-related inhibitor (ATRi) RP-3500 in patients (pts) with advanced solid tumors harboring synthetic lethal (SL) genomic alterations

Background: RP-3500 is a novel potent and selective ATRi. A genome-wide CRISPR/Cas9-based screening platform (SNIPRx) was utilized to identify and validate synthetic lethal (SL) genomic alterations that predict sensitivity to RP-3500. This is the first presentation of data from the ongoing Phase I TRESR (Treatment Enabled by SNIPRx) study. METHODS: Pts with advanced solid tumors harboring RP-3500 sensitizing alterations were recruited. Pts received oral RP-3500 in 21-day cycles on different doses and schedules using a BOIN design. Pharmacokinetic (PK) and pharmacodynamic (PD) studies were conducted in serial tumor and/or blood samples. Biomarker tests included somatic and germline NGS, including zygosity studies, ATM and γH2AX IHC, and circulating tumor DNA (ctDNA). RESULTS: 62 pts (mean age 62 y, 42% males, 43% ≥5 prior lines of therapy) received RP-3500 (range: 1–8+ cycles). 44 pts remained on RP-3500 at the June 4, 2021, data cut-off. Tumors with ATM (n=26), BRCA1/2 (n=16), CDK12 (n=5) and other (n=20) molecular alterations were included. Germline (22 germline and 15 somatic, 25 pending) and zygosity status (10 bi-allelic and 5 mono-allelic, 46 pending) will be presented. Treatment-related adverse events (TRAEs) were mostly Grade (G)1 and transient. TRAEs occurring in &gt;10% of pts were limited to anemia (all grades 37%, G3 26%, G4–5 0%) and fatigue (all grades 13%, G3 2%). Other ≥G3 TRAEs occurred in &lt;5% of pts and included thrombocytopenia (4.8%) and neutropenia (1.6%). No pts discontinued RP-3500 due to TRAEs, 17/62 discontinued due to progressive disease or clinical progression and 1/62 due to withdrawal of consent. RP-3500 plasma exposures showed a dose-dependent increase with T1/2 of 6 hrs. Once-daily dosing was sufficient to meet RP-3500 exposure requirements set from pre-clinical studies. Tumor γH2AX induction (median increase =140%; p-value =0.02) was seen across doses and genotypes confirming target modulation. Declines in variant allele frequencies (&gt;50%) in ctDNA were observed in 8/14 evaluable pts and correlated with antitumor activity (Pearson correlation coefficient =0.65; p-value =0.015). Of 31 pts evaluable for response, 14 (45%) had tumor regression on at least 1 radiologic evaluation. Objective responses were seen in 6 pts: 4 RECISTv1.1 partial responses in tumors with CDK12 and BRCA1 alterations (2 confirmed; 2 unconfirmed), and 2 PCWG3 in tumors with ATM loss. Six pts had stable disease ≥4 cycles. CONCLUSIONS: The TRESR study represents the largest biomarker-driven FIH trial for a single agent ATRi and validates prospective pt selection based on the presence of SL genomic alterations. RP-3500 shows a robust PK/PD profile, preliminary anti-tumor activity, and predictable and manageable on-target anemia (&lt;30% G3, no G4/5) with low potential for off-target toxicity. Enrollment continues, including combinations with PARPi and other therapies. Clinical trial information: NCT04497116.

Citation Format: Timothy Yap, Elizabeth Lee, David Spigel, Elisa Fontana, Martin Højgaard, Stephanie Lheureux, Niharika B. Mettu, Louise Carter, Ruth Plummer, Danielle Ulanet, Peter Manley, Ying Jiang, Ezra Rosen. First-in-human biomarker-driven phase I TRESR trial of ataxia telangiectasia and Rad3-related inhibitor (ATRi) RP-3500 in patients (pts) with advanced solid tumors harboring synthetic lethal (SL) genomic alterations [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 CC04-01.

A Phase 1a/b Open‑Label, Dose‑Escalation Study of Etigilimab Alone or in Combination with Nivolumab in Patients with Locally Advanced or Metastatic Solid Tumors

PURPOSE

TIGIT is a co-inhibitory receptor of T cell and natural killer cell activity. Targeting TIGIT with or without PD-1/PD-L1 checkpoint inhibition may enhance anti-tumor immunity.

PATIENTS AND METHODS

This Phase 1a/b trial was a first-in-human, open label, multicenter, dose escalation and expansion study in patients with locally advanced or metastatic solid tumors. Using 3+3 design, patients underwent 14-day treatment cycles with anti-TIGIT antibody etigilimab alone (phase 1a; 0.3, 1.0, 3.0, 10.0, 20.0 mg/kg intravenously) or in combination with anti-PD-1 antibody nivolumab (phase 1b; 3.0, 10.0, 20.0 mg/kg etigilimab and 240 mg nivolumab). Primary objective was safety and tolerability.

RESULTS

Thirty-three patients were enrolled (Phase 1a, n=23; Phase 1b, n=10). There were no DLTs. MTD for single and combination therapy was not determined; maximum administered dose was 20 mg/kg. The most commonly reported adverse events (AEs) were rash (43.5%), nausea (34.8%) and fatigue (30.4%) in Phase 1a and decreased appetite (50.0%), nausea (50.0%) and rash (40%) in Phase 1b. Six patients experienced Grade {greater than or equal to}3 treatment-related AEs. In phase 1a, 7 patients (30.0%) had stable disease. In Phase 1b, 1 patient had a partial response; 1 patient had prolonged stable disease of nearly 8 months. Median progression-free survival was 56.0 days (Phase 1a) and 57.5 days (Phase 1b). Biomarker correlative analyses demonstrated evidence of clear dose-dependent target engagement by etigilimab.

CONCLUSION

Etigilimab had an acceptable safety profile with preliminary evidence of clinical benefit alone and in combination with nivolumab and warrants further investigation in clinical trials.

Randomized phase II study of the Bruton tyrosine kinase inhibitor acalabrutinib, alone or with pembrolizumab in patients with advanced pancreatic cancer

Background

The immunosuppressive desmoplastic stroma of pancreatic cancer represents a major hurdle to developing an effective immune response. Preclinical studies in pancreatic cancer have demonstrated promising anti-tumor activity with Bruton tyrosine kinase (BTK) inhibition combined with programmed cell death receptor-1 (PD-1) blockade.

Methods

This was a phase II, multicenter, open-label, randomized (1:1) clinical trial evaluating the BTK inhibitor acalabrutinib, alone (monotherapy) or in combination with the anti-PD-1 antibody pembrolizumab (combination therapy). Eligible patients were adults with histologically confirmed metastatic or locally advanced unresectable pancreatic ductal adenocarcinoma with an Eastern Cooperative Oncology Group Performance Status (ECOG PS) ≤1 who had received at least one prior systemic therapy. Oral acalabrutinib 100 mg twice daily was administered with or without intravenous pembrolizumab 200 mg on day 1 of each 3-week cycle. Peripheral blood was analyzed for changes in immune markers, and tumors from exceptional responders were molecularly analyzed.

Results

A total of 77 patients were enrolled (37 monotherapy; 40 combination therapy) with a median age of 64 years; 77% had an ECOG PS of 1. The median number of prior therapies was 3 (range 1–6). Grade 3–4 treatment-related adverse events were seen in 14.3% of patients in the monotherapy arm and 15.8% of those in the combination therapy arm. The overall response rate and disease control rate were 0% and 14.3% with monotherapy and 7.9% and 21.1% with combination therapy, respectively. Median progression-free survival was 1.4 months in both arms. Peripheral blood flow analysis demonstrated consistent reductions in granulocytic (CD15+) myeloid-derived suppressor cells (MDSCs) over time. Two exceptional responders were found to be microsatellite stable with low tumor mutation burden, low neoantigen load and no defects in the homologous DNA repair pathway.

Conclusions

The combination of acalabrutinib and pembrolizumab was well tolerated, but limited clinical activity was seen with either acalabrutinib monotherapy or combination therapy. Peripheral reductions in MDSCs were seen. Efforts to understand and target the pancreatic tumor microenvironment should continue.

Trial registration number

NCT02362048.

Results of a phase 1 dose-escalation study of AMV564, a novel T-cell engager, alone and in combination with pembrolizumab in patients with relapsed/refractory solid tumors

2555

Background: Myeloid-derived suppressor cells (MDSC) contribute to an immunosuppressive tumor environment and are a barrier to immune therapy. CD33 signaling in immature myeloid cells promotes expansion of MDSC and production of immunosuppressive factors. AMV564 is a potent T cell engager that selectively depletes MDSC while promoting T cell activation and proliferation, via preferential binding to areas of high CD33 density. Methods: In this 3+3 dose escalation study, patients with relapsed/refractory solid tumors for whom no recognized standard therapy exists received AMV564 once daily via subcutaneous (SC) injection on Days 1-5 and 8-12 of a 21-day cycle, either alone or in combination with pembrolizumab (200 mg IV q3w). Study endpoints included incidence and severity of adverse events (AEs), pharmacokinetics (PK), and preliminary anti-tumor activity (using RECISTv1.1 criteria). Results: As of January 29, 2021, 20 patients were dosed in 3 monotherapy dose cohorts (15, 50, and 75 mcg/day), and 10 patients were dosed in 3 combination therapy cohorts (5, 15, and 50 mcg/day). Enrolled patients were: median age 64 years, 47% female, had received median 3.5 prior lines of therapy; 7 patients (35%) had received prior checkpoint inhibitor therapy (6 monotherapy patients, 1 combination therapy patient). No dose-limiting toxicity was observed and a maximum-tolerated dose was not reached in either the monotherapy or combination therapy cohorts. The most common treatment-related AEs (occurring in > 10% of patients, in order of decreasing frequency) in the monotherapy cohort were pyrexia, injection site reactions, fatigue, anemia, hypotension, pruritis, chills, and nausea. There were 2 cases of grade 2 cytokine release syndrome (CRS) at 75 mcg/day, both of which resolved after anti-IL6 therapy and study treatment was resumed. The most common treatment-related AEs in the combination cohorts (> 10% frequency) were injection site reaction, pyrexia, fatigue, pruritis, and anemia. No cases of CRS were noted in the combination cohorts. In preliminary PK analysis, estimated median plasma half-life for AMV564 after SC injection was > 48 hours, with dose-related increases in peak plasma concentration. Clinical responses were seen with monotherapy and combination therapy, including a complete response (CR) in a monotherapy-treated patient with ovarian cancer refractory to all standard therapies and anti-PD-1 therapy. Conclusions: AMV564 was well tolerated across multiple dose levels as monotherapy and in combination with pembrolizumab. Subcutaneous injection resulted in clinically relevant plasma exposures. Single-agent and combination therapy anti-tumor activity was observed. Further exploration of AMV564 clinical efficacy in expansion cohorts is ongoing. Clinical trial information: NCT04128423.

A case report of microsatellite instability (MSI)-high, HER2 amplified pancreatic adenocarcinoma with central nervous system metastasis

Pancreatic adenocarcinoma commonly presents as metastatic disease and harbors a dire prognosis due to its aggressive behavior, propensity for resistance to therapies, and lack of targetable driver mutations. Additionally, despite advances in other cancers, immunotherapy has been ineffective in this disease thus far and treatment remains centered around cytotoxic chemotherapy. Here, we present a case of a patient with pancreatic adenocarcinoma harboring both high microsatellite instability (MSI-H) and HER2 amplification. After an initial response to standard-of-care chemotherapy with FOLFIRINOX followed by progression, she was treated with dual immune checkpoint blockade, which resulted in a period of disease control. This was complicated by the development of autoimmune hypophysitis and an incidental finding of brain metastasis on magnetic resonance imaging (MRI). Her extracranial disease progressed while receiving stereotactic radiosurgery, with findings of lymphangitic spread in her lungs, and her treatment was changed to gemcitabine/nab-paclitaxel with trastuzumab. This resulted in a degree of extracranial disease control, though she experienced progressive brain metastases despite radiation and therapeutic switch to lapatinib and trastuzumab. Ultimately, the patient developed leptomeningeal disease which was not controlled by intrathecal trastuzumab. Given the rarity of central nervous system metastasis, HER2 amplification, and MSI in pancreatic cancer, this patient's presentation represents a confluence of multiple unique features. This case highlights the clinical value of up-front next-generation sequencing in metastatic pancreatic cancer and the ability of pancreatic cancer with actionable molecular variants to develop atypical sites of disease and adaptive resistance.

KEYlargo: A phase II study of first-line pembrolizumab (P), capecitabine (C), and oxaliplatin (O) in HER2-negative gastroesophageal (GE) adenocarcinoma

228

Background: Gastric and esophageal adenocarcinomas are a leading cause of cancer death worldwide. Many of these patients (pts) present with locally advanced unresectable or metastatic disease and are treated with combination cytotoxic chemotherapy. Single agent P is FDA approved for patients with recurrent locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma (GEJ) whose tumors have a combined positive score (CPS) ≥ 1 after disease progression on or after two lines of therapy including fluoropyrimidine and platinum and her2/neu-targeted therapy (if indicated). More effective therapy is needed earlier in the disease trajectory. We conducted a single-arm phase II trial to establish the safety and efficacy of first-line C and O + P. Methods: Pts with previously untreated metastatic GE adenocarcinoma regardless of PDL-1 status received intravenous (IV) P 200mg with IV O 130mg/m2 every three weeks and oral C 850mg/m2 twice daily for 14 days on/7 days off. After the 6 patient safety cohort, pts first completed a biomarker cycle that included fresh tumor biopsy before P and one week after P before chemotherapy started. Archived FFPE tumor samples were also obtained from all pts with available tissue. The primary endpoint was progression free survival (PFS); secondary endpoints included response rate (RR) and overall survival (OS). Results: 36 pts were enrolled and 34 pts were evaluable for efficacy (1 pt withdrew for personal reasons before end of cycle 1 and 1 pt had immune-related toxicity during cycle 1 and was taken off study before any efficacy assessment). 9 pts (26%) had an esophageal primary, 18 pts (53%) had a GEJ primary and 7 pts (21%) had a gastric primary. Median PFS was 7.6 months [95% CI: 5.8 to 12.2], RR was 72.7% [95% CI: 57% to 88%], and median OS was 15.8 months [95% CI: 11.6 to NE]. 27 patients (81.8%) had decrease in disease burden (ranging from -19% to -100%). After > 18 months of follow-up, 5 patients remained in durable complete response (CR). Immune-mediated treatment related adverse events (TRAEs) included thyroid disorders (n=5; 14%), colitis (n=4; 11%), adrenal insufficiency (n=2; 5%), and type 1 diabetes (n=1). Sixteen patients (44%) experienced grade 3 or 4 TRAEs. There were no grade 5 TRAEs. Conclusions: The combination of C and O + P had acceptable safety and significant clinical activity. These promising results indicate that C and O + P merits further study as a first line option for patients with unresectable locally advanced or metastatic GE adenocarcinoma. Updated survival and correlative data will be presented. Clinical trial information: NCT03342937.

Safety and efficacy of pemigatinib plus pembrolizumab combination therapy in patients (pts) with advanced malignancies: Results from FIGHT-101, an open-label phase I/II study

3606

Background: Pemigatinib (INCB054828) is a selective fibroblast growth factor receptor (FGFR) 1–3 inhibitor with demonstrated efficacy as monotherapy in phase 1/2 (FIGHT-101) and phase 2 (FIGHT-201, -202, -203) trials in pts with advanced cancer. Here, we present preliminary safety, efficacy, and pharmacokinetic (PK) data for pemigatinib (PEMI) combined with pembrolizumab (PEMBRO), a programmed cell death protein-1 (PD-1) inhibitor, in pts with refractory advanced malignancies enrolled in the ongoing FIGHT-101 trial (NCT02393248). Methods: FIGHT-101 includes monotherapy (part 1 and 2) and combination therapy (part 3) cohorts. This analysis is based on pts enrolled in the PEMI + PEMBRO combination dose finding (3a) and dose expansion (3b) cohorts. Eligible adults had advanced malignancies who had progressed after prior therapy and for whom PEMBRO treatment was relevant; pts in part 3b had FGF/FGFR alterations. Pts received oral PEMI at 9 mg or 13.5 mg QD on an intermittent dosing (ID) schedule (21-day cycle, 14-day on/7-day off), or 13.5 mg QD on a continuous dosing (CD) schedule, plus PEMBRO 200 mg IV on day 1 of each 21-day cycle. Results: At data cutoff (August 30, 2019), 23 pts had received PEMI + PEMBRO; 22 (96%) had discontinued therapy (disease progression, 70%). Most frequent tumors were NSCLC (n = 3), bladder (n = 3), pancreatic, testicular, and sarcoma (each n = 2). Of 19 enrolled pts with baseline FGF/FGFR data; 5 had FGFR mutations or rearrangements. No dose-limiting toxicities occurred with PEMI + PEMBRO. The recommended PEMI dose combined with PEMBRO was 13.5 mg QD. Most frequent all-cause, all-grade (Gr) adverse events for ID (n = 17) were hyperphosphatemia (n = 14 [82%]; Gr ≥3, n = 0), anemia (n = 9 [53%]; Gr ≥3, n = 3 [18%]), and decreased appetite (n = 9 [53%]; Gr ≥3, n = 0); for CD (n = 6), hyperphosphatemia (n = 5 [83%]; Gr ≥3, n = 0), and dry mouth (n = 4 [67%]; Gr ≥3, n = 0). One pt discontinued, 2 reduced dose, and 13 interrupted dose due to AEs (none for hyperphosphatemia; dose interruption mainly for gastrointestinal AEs [n = 5]). One fatal AE occurred (suicide, not treatment-related). PK parameters for PEMI in the PEMI + PEMBRO combination were comparable with those for PEMI monotherapy. Five pts had partial response (3 had FGFR rearrangements or mutations); 5 pts had stable disease. Conclusions: PEMI + PEMBRO combination therapy was tolerable with no new safety signals, and demonstrated preliminary antitumor activity in pts with advanced malignancies including those with FGF/FGFR alterations. Clinical trial information: NCT02393248 .

A phase I study of gemcitabine + dasatinib (gd) or gemcitabine + dasatinib + cetuximab (GDC) in refractory solid tumors

PURPOSE

This study was conducted to define the maximum tolerated dose (MTD), recommended phase two dose (RPTD), and toxicities of gemcitabine + dasatinib (GD) and gemcitabine + dasatinib + cetuximab (GDC) in advanced solid tumor patients.

METHODS

This study was a standard phase I 3 + 3 dose escalation study evaluating two combination regimens, GD and GDC. Patients with advanced solid tumors were enrolled in cohorts of 3-6 to either GD or GDC. Gemcitabine was dosed at 1000 mg/m² weekly for 3 of 4 weeks, dasatinib was dosed in mg PO BID, and cetuximab was dosed at 250 mg/m² weekly after a loading dose of cetuximab of 400 mg/m². There were two dose levels for dasatinib: (1) gemcitabine + dasatinib 50 mg ± cetuximab, and (2) gemcitabine + dasatinib 70 mg ± cetuximab. Cycle length was 28 days. Standard cycle 1 dose-limiting toxicity (DLT) definitions were used. Eligible patients had advanced solid tumors, adequate organ and marrow function, and no co-morbidities that would increase the risk of toxicity. Serum, plasma, and skin biopsy biomarkers were obtained pre- and on-treatment.

RESULTS

Twenty-five patients were enrolled, including 21 with pancreatic adenocarcinoma. Three patients received prior gemcitabine. Twenty-one patients were evaluable for toxicity and 16 for response. Four DLTs were observed: Grade (Gr) 3 neutropenia (GDC1, n = 1), Gr 3 ALT (GD2, n = 2), and Gr 5 pneumonitis (GDC2, n = 1). Possible treatment-emergent adverse events (TEAEs) in later cycles included: Gr 3-4 neutropenia (n = 7), Gr 4 colitis (n = 1), Gr 3 bilirubin (n = 2), Gr 3 anemia (n = 2), Gr 3 thrombocytopenia (n = 2), Gr 3 edema/fluid retention (n = 1), and Gr 3 vomiting (n = 3). Six of 16 patients (3 of whom were gemcitabine-refractory) had stable disease (SD) as best response, median duration = 5 months (range 1-7). One gemcitabine-refractory patient had a partial response (PR). Median PFS was 2.9 months (95% CI 2.1, 5.8). Median OS was 5.8 months (95% CI 4.1, 11.8). Dermal wound biopsies demonstrated that dasatinib resulted in a decrease of total and phospho-Src levels, and cetuximab resulted in a decrease of EGFR and ERBB2 levels.

CONCLUSIONS

The MTD/RPTD of GD is gemcitabine 1000 mg/m² weekly for 3 of 4 weeks and dasatinib 50 mg PO BID. The clinical activity of GD seen in this study was modest, and does not support its further investigation in pancreatic cancer.

BACCI: A phase II randomized, double-blind, placebo-controlled study of capecitabine bevacizumab plus atezolizumab versus capecitabine bevacizumab plus placebo in patients with refractory metastatic colorectal cancer

TPS873

Background: Initial treatment of metastatic colorectal cancer (mCRC) involves a 5-fluorouracil based chemotherapy regimen, often in combination with anti-VEGF therapy. Upon disease progression, multiple studies have suggested a benefit for continued anti-VEGF therapy. There is increasing evidence that VEGF plays a role in cancer immune evasion. Targeting of inflammatory and immune checkpoints are attractive approaches to enhance the benefits of anti-VEGF therapy. The safety and activity of the anti-PD-L1 antibody atezolizumab with bevacizumab and with 5-FU, oxaliplatin, and bevacizumab have been recently reported; the combinations were well-tolerated and suggested clinical activity. Therefore, bevacizumab may increase the immunogenicity of colorectal cancers, and the combination of atezolizumab plus bevacizumab may be associated with clinically meaningful response rates and disease control. Furthermore, there may be candidate biomarkers that may identify those patients most likely to benefit from this combination. Methods: In this randomized, double-blind, multicenter, placebo-controlled phase II study, 135 patients with mCRC will be randomized 2:1 to receive capecitabine/bevacizumab/atezolizumab or capecitabine/bevacizumab/placebo. Patients with prior PD-L1/PD-1 therapy are ineligible. Primary and secondary efficacy will be conducted using ITT analysis. Safety analyses will include all randomized patients who receive at least one dose of study treatment. The primary objective is PFS. The secondary objectives are ORR, OS, safety, and tolerability. The primary comparison will be superiority of the active treatment for the PFS endpoint, atezolizumab versus placebo testing at 1-sided α = 0.1 (log rank test). A PFS hazard ratio of 0.618 (active treatment versus placebo) is detectable with 86% power (1 sided α = 0.1). No interim analyses for futility or efficacy will be conducted. A subset analysis will be performed in the microsatellite-high patients looking at potential differences in PFS and OS. Trial is active and currently recruiting patients. Clinical trial information: NCT02873195.

Clinical Insights Into the Biology and Treatment of Pancreatic Cancer

Pancreatic cancer is a devastating disease with a universally poor prognosis. In 2015, it is estimated that there will be 48,960 new cases of pancreatic cancer and that 40,560 people will die of the disease. The 5-year survival rate is 7.2% for all patients with pancreatic cancer; however, survival depends greatly on the stage at diagnosis. Unfortunately, 53% of patients already have metastatic disease at diagnosis, which corresponds to a 5-year survival rate of 2.4%. Even for the 9% of patients with localized disease confined to the pancreas, the 5-year survival is still modest at only 27.1%. These grim statistics highlight the need for ways to identify cohorts of individuals at highest risk, methods to screen those at highest risk to identify preinvasive pathologic precursors, and development of effective systemic therapies. Recent clinical and translational progress has emphasized the relationship with diabetes, the role of the stroma, and the interplay of each of these with inflammation in the pathobiology of pancreatic cancer. In this article, we will discuss these relationships and how they might translate into novel management strategies for the treatment of this disease.

Use of molecular biomarkers to inform adjuvant therapy for colon cancer

The decision about who may derive benefit from adjuvant chemotherapy in colon cancer is often a difficult one for clinicians. While multiple trials have demonstrated that adjuvant chemotherapy reduces the risk of recurrence and improves overall survival in patients with stage III disease, the data supporting the use of adjuvant chemotherapy in patients with stage II disease are not as compelling. Because adjuvant therapy can have significant toxicity, tools to help clinicians determine who may derive a benefit from therapy are of the utmost importance. Recent advances in high throughput technologies have led to the identification of molecular biomarkers-including microsatellite instability (MSI), loss of heterozygosity (LOH), p53, Kirsten rat sarcoma viral oncogene homolog (KRAS), v-raf murine sarcoma viral oncogene homolog B1 (BRAF), thymidylate synthase (TS), and excision repair cross-complementation group 1 (ERCC1)--as well as various multigene assays that are being studied for their ability to offer both prognostic and predictive information to clinicians. Here we review the current knowledge about molecular biomarkers that may aid the clinician in offering personalized cancer therapy based on the genetic landscape of an individual patient's tumor.

The Nuclear Receptor-Coactivator Interaction Surface as a Target for Peptide Antagonists of the Peroxisome Proliferator-Activated Receptors

The peroxisome proliferator-activated receptors (PPARα, PPARδ, and PPARγ) constitute a family of nuclear receptors that regulates metabolic processes involved in lipid and glucose homeostasis. Although generally considered to function as ligand-regulated receptors, all three PPARs exhibit a high level of constitutive activity that may result from their stimulation by intracellularly produced endogenous ligands. Consequently, complete inhibition of PPAR signaling requires the development of inverse agonists. However, the currently available small molecule antagonists for the PPARs function only as partial agonists, or their efficacy is not sufficient to inhibit the constitutive activity of these receptors. Due to the lack of efficacious antagonists that interact with the ligand-binding domain of the PPARs, we decided to target an interaction that is central to nuclear receptor-mediated gene transcription: the nuclear receptor-coactivator interaction. We utilized phage display technology to identify short LXXLL-containing peptides that bind to the PPARs. Analysis of these peptides revealed a consensus binding motif consisting of HPLLXXLL. Cross-screening of these peptides for binding to other nuclear receptors enabled the identification of a high-affinity PPAR-selective peptide that has the ability to repress PPARγ1-dependent transcription of transfected reporter genes. Most importantly, when introduced into HepG2 cells, the peptide inhibited the expression of endogenous PPARγ1 target genes, adipose differentiation-related protein and mitochondrial 3-hydroxy-3-methylglutaryl coenzyme A synthase 2. This work lends support for the rational development of peptidomimetics that block receptor-mediated transcription by targeting the nuclear receptor-coactivator interaction surface.