ETCTN 10476: A randomized phase 2 study of combination atezolizumab and varlilumab (CDX-1127) with or without addition of cobimetinib in previously treated unresectable biliary tract cancer

TPS639

Background: The combination of the MEK inhibitor, Cobimetinib, with the PD-L1 antagonist, Atezolizumab, significantly improved progression-free survival (PFS) compared to Atezolizumab monotherapy in patients with advanced biliary tract cancer (BTC) following first-line chemotherapy (NCT03201458). Interrogation of biospecimens from this trial and parallel pre-clinical work showed that the addition of MEK inhibition enhanced tumor immunogenicity but simultaneously had detrimental effects on host T-cell activation and priming. The addition of immune co-stimulants rescues T-cell function in the setting of systemic MEK inhibition in vivo. Unlike other immune co-stimulatory markers, CD27 is one of the most positively differentially expressed receptors in the TME post-treatment with combined MEK inhibition and PD-L1 blockade. We hypothesize that addition of CD27 immune agonism to the combination of PD-L1 and MEK inhibition can improve immunotherapy outcomes in patients with BTC. Methods: We are conducting an open-label, randomized ph 2 trial evaluating a PD-L1 inhibitor (atezolizumab) in combination with a CD27 immune agonist (CDX-1127 [Varlilumab]) with or without addition of a MEK inhibitor (Cobimetinib) in patients with unresectable, previously treated, BTC. Key inclusion criteria include: adults with pathologically-confirmed BTC, s/p 1-2 lines of systemic therapy (including any FDA-approved targeted therapies) in the metastatic setting, measurable disease, ECOG performance status ≤1, adequate baseline organ and marrow function. Patients who have received gem-cis-durvalumab, and/or prior FGFR2/IDH1 targeted therapy are eligible for enrollment. The study is planned for 64 evaluable subjects (32 subjects per treatment arm) randomized in a 1:1 ratio, stratified by site of BTC location, to either Atezolizumab + CDX-1127 or Atezolizumab + CDX-1127 + Cobimetinib. During the 28-day treatment cycles, all patients receive Atezolizumab (840mg flat dose) and CDX-1127 (3mg/kg) infusions on D1 and D15. For those randomized to the triplet regimen arm, the additional Cobimetinib will be dosed orally at 60mg daily on days 1-21. Overall response rate and PFS are co-primary endpoints. A clinically meaningful improvement in ORR warranting further study is 20%. The primary correlative outcome is treatment-related changes in CD8+ infiltrating T cells. After an initial safety lead-in, a planned interim efficacy analysis will take place following enrollment of the first 18 patients in each treatment arm. Currently, 14 participants (n=6 [triplet arm], n=8 [doublet arm]), have been enrolled & treated on protocol. This study is sponsored by the NCI Cancer Therapy Evaluation Program and is open nationally at designated NCI Experimental Therapeutics Clinical Trials Network sites. Clinical trial information: NCT04941287 .

A phase II study of atezolizumab (ATEZO) and bevacizumab (BEV) in combination with Y90 TARE in patients (pts) with hepatocellular carcinoma (HCC): Y90+/- BEAT

TPS629

Background: The anti–PD-L1 antibody ATEZO prevents PD-L1 from interacting with PD-1 and B7.1, thus reinvigorating antitumor T cell activity. Anti-VEGF BEV can increase dendritic cell maturation, enhance T cell infiltration, and reduce myeloid-derived suppressor cells and regulatory T-cells in tumors. This combination has been FDA approved for first-line treatment of advanced HCC based on the IMbrave150 study. On the other hand, locoregional radiotherapy (e.g., Y90 TARE) enhances the diversity of the intratumoral T cell receptor repertoire. It is the standard of care for pts with intermediate-stage HCC (iHCC). Based on preclinical and clinical data, we hypothesize that the combination of Y90 TARE, BEV, and ATEZO induces synergistic tumor-killing. Methods: This is an open-label, multicenter, randomized phase II study of Y90 TARE and BEV plus ATEZO compared with Y90 TARE alone in pts with unresectable IHCC (NCT04541173). The primary study objective is to assess and compare the progression-free survival (PFS) (per mRECIST 1.1) of pts in each arm. The main secondary objective is to determine the safety and tolerability (CTCAE v5) of TARE combined with ATEZO and BEV in pts with HCC. Exploratory objectives are to assess the role of the immunoscore and PD-L1 expression levels in the prediction of improved clinical outcome in pts receiving Y-90 TARE and BEV plus ATEZO; the composition of tumor-infiltrating immune cell subtypes in predicting response to a chosen therapy; how Y90 therapy affects the proportion of antigen-presenting cells in the tumor; and symptoms experienced by pts receiving TARE and BEV plus ATEZO treatment, using patient-reported outcomes. Eligible pts have either HCC that is not amenable to surgical resection, confirmed by pathology review, or at least BCLC stage B HCC outside of downstaging criteria. Other standard eligibility criteria apply. Pts must have a pretreatment liver biopsy taken and then be randomized 1:1 to TARE (Arm A) or TARE followed by ATEZO and BEV (Arm B). Pts will have TARE mapping during week (wk) 1 and TARE treatment during wk 2. In Arm B, pts will start BEV plus ATEZO 4 wks (±1 wk) after TARE treatment. Pts will have abdominal MRI or CT scans every 12 weeks, CT scans of the chest every 24 wks. Disease progression will be captured by both RECIST 1.1 and mRECIST. We plan to assess the safety of TARE with BEV and ATEZO in the first 10 pts randomized to Arm B for two cycles. If there are no Grade ≥ 3 unexpected toxicities possibly, probably or definitely related to combined TARE plus BEV plus ATEZO, the study will continue to accrue 128 pts in total. Pts will continue study treatment (Arm B) for a total of 24 months from initiation of TARE or until intolerable toxicity or disease progression occur, whichever is earlier. Clinical trial information: NCT04541173 .

A phase I study of a mutant KRAS-targeted long peptide vaccine combined with ipilimumab/nivolumab in resected pancreatic cancer and MMR-proficient metastatic colorectal cancer

TPS814

Background: Novel strategies are needed to improve immune responses in “cold” tumors such as pancreatic ductal adenocarcinoma (PDAC) and mismatch repair-proficient colorectal cancer (MMRp CRC). As a frequent oncogenic driver, mutant KRAS (mKRAS) neoantigens are attractive targets to augment anti-tumor immunity in both diseases. Recently, adoptive transfer of mKRAS G12D-specific T cells has shown durable tumor regressions in patients with metastatic CRC and PDAC (Tran et. al., 2020; Leidner et. al., 2022). Furthermore, our preclinical work has demonstrated that combining a mKRAS neoantigen vaccine with immune-modulating agents prevents progression of premalignant lesions to PDAC in mice (Keenan et. al., 2014). Based on this rationale, our study pairs a pooled synthetic long peptide (SLP) mKRAS vaccine with dual checkpoint blockade to assess safety and immunogenicity in patients with resected PDAC and chemorefractory MMRp CRC. Methods: This is a first-in-human, single-arm, open-label phase I trial evaluating a pooled SLP mKRAS vaccine combined with ipilimumab/nivolumab (ipi/nivo) in patients with resected PDAC (Cohort A, n = 12) and MMRp metastatic CRC (Cohort B, n = 12) The vaccine consists of poly-ICLC adjuvant admixed with SLPs corresponding to six common mKRAS subtypes: G12D, G12R, G12V, G12A, G12C, and G13D. In priming phase, the mKRAS vaccine is given on days 1, 8, 15, and 22 along with ipi/nivo. In boost phase, the mKRAS vaccine is given on weeks 13, 21, 29, 37, and 45 along with nivo alone. Cohort A patients who remain disease-free can continue to receive boost vaccines in a 12-month extended treatment phase. Eligible patients must have molecular tumor testing that demonstrates one of the six KRAS mutations listed above. Cohort A patients must be disease-free following completion of adjuvant chemotherapy within 6 months prior to study entry. Cohort B patients must have confirmed MMRp status, exposure to ≥ 2 prior lines of standard chemotherapy, and measurable disease amenable to biopsies at baseline and week 7. The co-primary endpoints of this study are safety and T cell response. Adverse events will be graded per NCI CTCAE v5.0. T cell response will be determined by the maximal percent change in IFNγ-producing mKRAS-specific T cell density within 16 weeks post-vaccination compared to baseline. Secondary endpoints include disease control and objective response rates at 16 weeks per RECIST v1.1/iRECIST (Cohort B only) as well as disease-free/progression-free and overall survival. Correlative studies will examine treatment-associated changes in T cell receptor (TCR) repertoire diversity by next-generation TCR sequencing of peripheral blood and tumor specimens. Patient accrual began in May 2020 and is completed for Cohort A. Enrollment is currently ongoing for Cohort B. Study drug support provided by Bristol Myers Squibb. Clinical trial information: NCT04117087 .

Neoadjuvant and adjuvant antitumor vaccination alone or combination with PD1 blockade and CD137 agonism in patients with resectable pancreatic adenocarcinoma

558

Background: Utilizing a vaccine that induces and activates host effector T cells and co-administering it with immune modulating agents that enhance anti-tumor T cell activity is a potential strategy for overcoming pancreatic adenocarcinoma’s (PDA) resistance to immunotherapy. Our prior clinical trial demonstrated a GM-CSF-secreting, allogeneic tumor cell vaccine (GVAX) increases infiltrating CD8+ T cells in PDA. Follow up preclinical work demonstrated therapeutic synergy between GVAX and PD-1inhibition (PD1) with efficacy further enhanced by CD137 agonism (CD137). Methods: This was a 3-arm trial of neoadjuvant & adjuvant GVAX-based therapy in resectable (r) PDA patients (pts). Adults with clinically resectable, untreated PDA were enrolled in 1 of 3 study treatments: Arm A (GVAX alone), Arm B (GVAX + PD1 [Nivolumab]), or arm C (GVAX + PD1 + CD137 [Urelumab]). Treatment was given as follows: Day 1 - Cyclophosphamide 200mg/m2 IV (All Arms), Nivolumab 480mg IV (Arms B, C), Urelumab 8mg IV (Arm C); Day 2 – GVAX ID (All Arms). Pts were treated at 3 timepoints: 1) once 2 weeks prior to surgery; 2) once post-surgical recovery prior to standard of care adjuvant chemotherapy (SOC); 3) every month (up to 4 mo) following completion of SOC (if disease-free). SOC regimes included (m)FOLFIRINOX, Gem +/- Cap/NAB-Paclitaxel. The study was powered for a primary biologic endpoint: treatment-related change in intratumoral CD8+CD137+ T cells. Clinical endpoints included disease-free survival (DFS: time from surgery to recurrence), overall survival (OS: time from surgery to death), and safety. Results: 38 pts (N = 15 [Arm A], N = 13 [Arm B], N = 10 [Arm C]) were eligible for efficacy analysis (had R0/R1 resection) and 45 pts (N = 17 [A], N = 17 [B], N = 11 [C]) were eligible for safety analysis (had ≥1 dose of study treatment). Demographics, surgical pathology features, and SOC durations were similar in all Arms. At median follow up of 23 mo [A], 26 mo [B], and 22 mo [C], median DFS (95% CI) was 14.82 mo (6.0, NA), 16.23 mo (7.49, NA) and not reached (16.33, NA) for Arms A, B, C, respectively. There was no DFS benefit to adding PD1 compared to GVAX alone (HR 0.98 [95% CI 0.42, 2.27], p = 0.96). Combination CD137 + PD1 + GVAX was associated with marginally significant improved DFS compared to GVAX alone (HR 0.38 [95%CI 0.12, 1.19], p = 0.097) and GVAX + PD1 (HR 0.38 [95%CI 0.12, 1.21], p = 0.103). Median OS (95% CI) was 25.0 mo (18.8, NA), 26.4 mo (20.3, NA), and not yet reached for Arms A, B, C, respectively. There were no serious adverse events. In Arm C, 1 pt had grade 3 rash that delayed treatment and there was 1 instance of grade 2 AST/ALT elevation. The biologic endpoint will be reported at the meeting. Conclusions: Despite a small sample size, combining GVAX with dual immune-targeting of PD-1 blockade and CD137 agonism was safe and may enhance DFS in rPDA pts treated in the perioperative and post-adjuvant settings. Clinical trial information: NCT02451982.

First-line stereotactic radiosurgery combined with systemic targeted and immune checkpoint inhibitor therapy in melanoma patients with newly diagnosed brain metastases

e13577

Background: Of solid tumors, melanoma has the highest propensity for central nervous system spread with historic median survivals of 5-8 months following brain metastasis diagnosis. We evaluated the impact of systemic BRAF targeted and immune checkpoint inhibitor (ICI) therapies on survival outcomes in patients receiving stereotactic radiosurgery (SRS) for melanoma brain metastases (MBM) and assessed patient treatment burden associated with prolonged survival. Methods: We retrospectively reviewed the demographics, disease characteristics, therapeutic regimens, overall survival, and first-year cumulative incidence of comorbid disease for patients with de novo MBM treated between 2013 and 2017 at a major melanoma referral center. Results: Among 123 newly diagnosed MBM patients:65% were male, 24%were 50 years old or less, 50% were BRAF mutated, 63% had multiple intracranial lesions at diagnosis . Locally, 73% received SRS as first-line treatment.Systemically, 73% received ICI, 46% received BRAF targeted therapy, and 12% received neither. With median follow up of 11 months (mo), totalcohort median OS was 13.2 mo, 20.5 mo for BRAF mutated patients, 10.8 mo for BRAF wild-type patients. Median OS for first-line SRS was 31.0 mo (47% 3-year OS) when combined with both ICI and BRAF targeted therapy, 17.5 mo (31% 3-year OS) when combined with ICI monotherapy, and 6.1 mo (22% 3-yr OS) with neither systemic therapy. SRS and BRAF targeted therapy were associated with improved OS. BRAF status, ICI therapy, intratumoral hemorrhage were not significant prognosticators for OS.At one-year follow-up, comorbid conditions with the greatest cumulative incidence were fatigue, nausea, intracranial hemorrhage, deep vein thrombosis, major depressive disorder, and pneumonia. Patients averaged one inpatient visit every 4.5 mo (1 week average length of stay), and 2 advanced imaging studies (MR/CT/PET-CT) per month following MBM diagnosis. Conclusions: In one of the largest reported MBM series, survival has improved markedly for patients receiving first-line brain radiosurgery combined with BRAF targeted therapies and immunotherapies. Simultaneously, longer life expectancy comes with increasing incidences of comorbid conditions reflecting an evolving complexity of and need for coordination of care for patients with MBM.

Clinical outcomes and the role of adjuvant therapy sequencing in Type II uterine cancer following definitive surgical treatment

PURPOSE OF INVESTIGATION

Because of rarity, consensus on adjuvant therapies for Type II endometrial cancers (BC) remains undefined. Reporting their institutional outcomes, the present authors assessed the impact of adjuvant therapies on recurrence and overall survival in women with 2009 FIGO Stage I-III Type II BC.

MATERIAL AND METHODS

The authors identified 108 women, treated with definitive surgery between 2000-2013, with pathologically-confirmed Type II EC (non-endometrioid [NEM, n=801 and high grade endometrioid [G3EEC, n=28]) Cox proportional hazard models were used to assess the effect of prognostic variables on disease-free (DFS) and overall survival (OS). Kaplan-Meier method was used to assess survival.

RESULTS

Of the 108 women, 83 (77%) were African American (AA). Fifty-nine (55%), 12 (11%), and 37 (34%) were Stage I, II, and III, respectively. Ninety-seven patients received adjuvant therapy: 52 (radiation only), four (chemotherapy only), and 40 (combined). During follow-up (median 41 months), 44 patients (41%) recurred. Five-year DFS was 53% overall (48% [NEM], 80% [G3EEC]). Five-year OS was 75% overall (68% [NEM], 95% [G3EEC]). On multivariate analysis, lower stage and adjuvant radiation improved DFS. Higher stage, NEM, and increasing age were poor prognostic indicators of OS.

CONCLUSION

Representing a large single institutional cohort for Type II BC, the present study's observed sur- vival rates are consistent with previous studies, despite the relatively high frequency of carcinosarcoma and Stage III/nodal disease. The protective effect on recurrence was not lost when radiation was delayed for chemotherapy. The present results support a multimodal adjuvant approach for treating all stages of invasive NEM EC.