Phase I study of ABBV-428, a mesothelin-CD40 bispecific, in patients with advanced solid tumors

BACKGROUND

CD40 agonist immunotherapy can potentially license antigen-presenting cells to promote antitumor T-cell activation and re-educate macrophages to destroy tumor stroma. Systemic administration of CD40 agonists has historically been associated with considerable toxicity, providing the rationale for development of tumor-targeted immunomodulators to improve clinical safety and efficacy. This phase I study assessed the safety, tolerability, preliminary antitumor activity, and preliminary biomarkers of ABBV-428, a first-in-class, mesothelin-targeted, bispecific antibody designed for tumor microenvironment-dependent CD40 activation with limited systemic toxicity.

METHODS

ABBV-428 was administered intravenously every 2 weeks to patients with advanced solid tumors. An accelerated titration (starting at a 0.01 mg/kg dose) and a 3+3 dose escalation scheme were used, followed by recommended phase II dose cohort expansions in ovarian cancer and mesothelioma, tumor types associated with high mesothelin expression.

RESULTS

Fifty-nine patients were treated at doses between 0.01 and 3.6 mg/kg. The maximum tolerated dose was not reached, and 3.6 mg/kg was selected as the recommended phase II dose. Seven patients (12%) reported infusion-related reactions. Treatment-related grade ≥3 treatment-emergent adverse events were pericardial effusion, colitis, infusion-related reaction, and pleural effusion (n=1 each, 2%), with no cytokine release syndrome reported. The pharmacokinetic profile demonstrated roughly dose-proportional increases in exposure from 0.4 to 3.6 mg/kg. Best response was stable disease in 9/25 patients (36%) treated at the recommended phase II dose. CD40 receptor occupancy >90% was observed on peripheral B-cells starting from 0.8 mg/kg; however, no consistent changes from baseline in intratumoral CD8+ T-cells, programmed death ligand-1 (PD-L1+) cells, or immune-related gene expression were detected post-ABBV-428 treatment (cycle 2, day 1). Mesothelin membrane staining showed greater correlation with progression-free survival in ovarian cancer and mesothelioma than in the broader dose escalation population.

CONCLUSIONS

ABBV-428 monotherapy exhibited dose-proportional pharmacokinetics and an acceptable safety profile, particularly for toxicities characteristic of CD40 agonism, illustrating that utilization of a tumor-targeted, bispecific antibody can improve the safety of CD40 agonism as a therapeutic approach. ABBV-428 monotherapy had minimal clinical activity in dose escalation and in a small expansion cohort of patients with advanced mesothelioma or ovarian cancer.

TRIAL REGISTRATION NUMBER

NCT02955251.

The biology and clinical development of MEK inhibitors for cancer

The mitogen-activated protein kinase kinases (MAPKK) MEK1 and MEK2 are integral members of the MAPK/ERK signaling pathway and are of interest in the development of anti-cancer therapeutics. The MAPK/ERK pathway is dysregulated in more than 30 % of cancers, predominately by mutations in RAS and BRAF proteins, and MEK serves as a potential downstream target for both of these. The biology of MEK inhibition is complex, as the molecule is differentially regulated by upstream RAS or RAF. This has impacted on the past development of MEK inhibitors as treatments for cancer and may be exploited in more rational, molecularly selected drug development plans in the future. The role of MEK in cancer and the mechanism of action of MEK inhibitors is reviewed. Furthermore, MEK inhibitors that are available in standard practice, as well as those most advanced in clinical development, are discussed. Finally, next steps in the development of MEK inhibitors are considered.

New developments in the treatment of metastatic melanoma - role of dabrafenib-trametinib combination therapy

Development of selective inhibitors of BRAF has improved the survival of patients with BRAF-mutant melanoma. The progression-free survival after treatment with a BRAF inhibitor is modest, however, and BRAF inhibitors induce cutaneous toxicity, likely due to paradoxical activation of the mitogen-activated protein kinase pathway. Combining selective BRAF and MEK inhibition, such as the BRAF inhibitor dabrafenib and the MEK inhibitor trametinib, has been shown to improve the response rate and progression-free survival in patients with advanced melanoma while significantly alleviating the paradoxical activation of mitogen-activated protein kinase. This combination treatment results in a reduction in skin toxicity relative to that seen with a BRAF inhibitor alone; however, addition of the MEK inhibitor adds other toxicities, such as pyrexia and gastrointestinal or ocular toxicity. While combined BRAF–MEK inhibition appears primed to become a standard molecular approach for BRAF-mutant melanoma, the utility of the combination has to be considered in the rapidly changing landscape of immunotherapeutics, such as immune checkpoint blockade using anti-cytotoxic T lymphocyte antigen-4 and anti-programmed death-1/programmed death-L1 antibodies. Here we review the development of the dabrafenib plus trametinib combination, the characteristics of each drug and the combination, and the role of this combination in the management of patients with BRAF-mutant melanoma.

BMS-986205, an indoleamine 2, 3-dioxygenase 1 inhibitor (IDO1i), in combination with nivolumab (nivo): Updated safety across all tumor cohorts and efficacy in advanced bladder cancer (advBC)

358

Background: Nivo (anti–PD-1) has shown durable responses and manageable safety (ORR, 19.6%; grade 3‒4 treatment-related AEs [TRAEs], 18%) in advBC (Sharma et al. Lancet Oncol 2017), but prolonging survival in more pts requires additional approaches to overcome tumor evasion mechanisms. IDO1 allows tumor escape through kynurenine (KYN) production, which stimulates regulatory T cells and suppresses effector T-cell proliferation. Anti─PD-1 can upregulate IDO1, supporting the rationale for combining nivo with an IDO1i. BMS-986205 is a selective, potent, once-daily (QD) oral IDO1i that works early in the IDO1 pathway to reduce KYN production. BMS-986205 + nivo showed favorable safety and efficacy in heavily pretreated pts with select solid tumors (Luke et al. SITC 2017; NCT02658890). Updated safety across all tumor cohorts and efficacy in the immuno-oncology (I-O)–naive advBC cohort are reported. Methods: Dose-escalation methods in this phase 1/2a, open-label study were previously described; during expansion, pts received BMS-986205 100 or 200 mg QD + nivo 240 mg IV Q2W or 480 mg IV Q4W. Objectives included safety and ORR by RECIST v1.1 (includes unconfirmed responses). Results: As of Mar 2018, 516 pts received BMS-986205 + nivo; 45% had ≥2 prior regimens. TRAEs occurred in 57% of pts (grade 3‒4, 12%), the most common being fatigue (15%) and nausea (12%); 19 pts (4%) discontinued due to TRAEs, and 3 pts ( < 1%) died due to a TRAE (myocarditis, Stevens-Johnson syndrome, and hepatic failure). In all treated pts and within the advBC cohort (n = 30), the frequency and severity of TRAEs and rate of discontinuation due to TRAEs was lower with the 100- vs 200-mg BMS-986205 dose. Among the 27 pts with I-O–naive advBC, with a median duration of follow-up of 24 wk, ORR was 37% (3 CRs, 7 PRs), and the DCR was 56%; ORR in pts with tumor PD-L1 ≥1% (Dako PD-L1 IHC 28-8 pharmDx assay; n = 14) vs < 1% (n = 10) was 50% vs 30%. Conclusions: BMS-986205 + nivo was well tolerated in heavily pretreated pts, and tolerability was improved with the 100-mg BMS-986205 dose. Preliminary evidence of efficacy was observed in advBC, supporting further evaluation of BMS-986205 + nivo. Clinical trial information: NCT02658890.

First-in-human trial of the PI3Kβ-selective inhibitor SAR260301 in patients with advanced solid tumors

BACKGROUND

Phosphoinositide 3-kinase (PI3K) β is the dominant isoform for PI3K activity in many phosphatase and tensin homolog (PTEN)-deficient tumor models. This was a first-in-human study to determine the maximum tolerated dose, safety, pharmacokinetics (PK), pharmacodynamics, and preliminary activity of SAR260301, a potent PI3Kβ-selective inhibitor (clinicaltrials.gov identifier NCT01673737).

METHODS

Successive cohorts of patients with advanced solid tumors received increasing doses of oral SAR260301 according to a Bayesian escalation with an overdose-control process based on the occurrence of dose-limiting toxicity in the first 28-day cycle. Adverse events, tumor response, PK, and the effect of food on PK were evaluated. Target engagement was assessed in platelets. Physiologically-based PK modeling was used for exposure predictions.

RESULTS

Twenty-one patients received treatment at doses ranging from 100 mg once daily to 440 mg/m² twice daily. Dose-limiting toxicities included 1 episode of grade 3 pneumonitis (400 mg twice daily) and 1 grade 3 γ-glutamyltransferase increase (600 mg twice daily). The maximum tolerated dose was not reached. The most frequently occurring treatment-related adverse events were nausea, vomiting, and diarrhea (14% each). Pharmacologically active concentrations were reached, but SAR260301 was rapidly cleared, and exposures associated with antitumor activity in preclinical models were not maintained at the highest dose tested. Food further decreased SAR260301 exposure.

CONCLUSIONS

SAR260301 had an acceptable safety profile, but exposure sufficient to inhibit the PI3K pathway was unachievable because of rapid clearance, and clinical development was terminated. These results demonstrate the importance of PK and pharmacodynamic assessments in early drug development. Cancer 2018;124:315-24. © 2017 American Cancer Society.

Inhibition of the Wnt/β-catenin pathway enhances antitumor immunity in ovarian cancer

Background:

The Wnt/β-catenin pathway is linked to tumorigenesis in a variety of tumors and promotes T cell exclusion and resistance to checkpoint inhibitors. We sought to determine whether a small molecule inhibitor of this pathway, WNT974, would impair tumor growth, affect gene expression patterns, and improve the immune response in human and murine ovarian cancer models.

Methods:

Human ovarian cancer cells were treated with WNT974 in vitro. RNAseq libraries were constructed and differences in gene expression patterns between responders and nonresponders were compared to The Cancer Genome Atlas (TCGA). Mice with subcutaneous or intraperitoneal ID8 ovarian cancer tumors were treated with WNT974, paclitaxel, combination, or control. Tumor growth and survival were measured. Flow cytometry and β-TCR repertoire analysis were used to determine the immune response.

Results:

Gene expression profiling revealed distinct signatures in responders and nonresponders, which strongly correlated with T cell infiltration patterns in the TCGA analysis of ovarian cancer. WNT974 inhibited tumor growth, prevented ascites formation, and prolonged survival in mouse models. WNT974 increased the ratio of CD8⁺ T cells to T regulatory cells (Tregs) in tumors and enhanced the effector functions of infiltrating CD4⁺ and CD8⁺ T cells. Treatment also decreased the expression of inhibitory receptors on CD8⁺ T cells. Combining WNT974 with paclitaxel further reduced tumor growth, prolonged survival, and expanded the T cell repertoire.

Conclusions:

These findings suggest that inhibiting the Wnt/β-catenin pathway may have a potent immunomodulatory effect in the treatment of ovarian cancer, particularly when combined with paclitaxel.

Lymphoma development in Bax transgenic mice is inhibited by Bcl-2 and associated with chromosomal instability

Bax is a Bcl-2 family member that promotes apoptosis but has paradoxical effects on lymphoma development in p53-deficient mice. To better understand the mechanism of Bax-induced lymphoma development, the effect of Bax levels, p53 status and Bcl-2 coexpression on lymphoma development were determined. In addition, DNA content and cytogenetics were performed on young (premalignant) Lck-Bax mice as measures of genetic instability. Bax promoted lymphoma development in p53-deficient mice in a dose-dependent manner. Bax expression also led to lymphoma development in both p53 +/- and +/+ animals. Ploidy analysis in mice prior to the onset of overt thymic lymphomas demonstrated that Lck-Bax transgenic mice were more likely to be aneuploid and demonstrate increased chromosome instability. With tumor progression, aneuploidy increased and Bax expression was maintained. Importantly, coexpression of Bcl-2 delayed lymphoma development in Lck-Bax transgenic mice. These data support a model in which increased sensitivity to apoptosis leads directly to chromosome instability in developing T cells and may explain a number of paradoxical observations regarding Bcl-2 family members and the regulation of cancer.

Neuromuscular block with doxacurium (BW A938U) in patients with normal or absent renal function

The characteristics of neuromuscular block induced by doxacurium were compared in patients with and without renal function. Seventeen patients with end stage chronic renal failure and 18 patients with normal renal function were anaesthetized with 0.5% halothane and nitrous oxide in oxygen and received doxacurium in an initial dose of 25 micrograms kg-1 (estimated from available data as an ED95 dose), with incremental doses of 5 micrograms kg-1. At the end of surgery, residual neuromuscular block was antagonized with either edrophonium 1.0 mg kg-1 or neostigmine 0.08 mg kg-1. There was no significant difference between the mean maximum blocks achieved with doxacurium: 17.4% (renal failure group) and 11.6% (control group) of control twitch heights, or between the mean times to achieve maximum block (10.9 min and 10.8 min, respectively). The mean duration of action of doxacurium, indicated by the time for twitch height to recover to 25% of control, was longer in the renal failure group (120.8 min vs 66.7 min in the control group) (ns). Similarly, the mean duration of action of increments was longer in the renal failure group (27.4 min vs 20.5 min in the control group). The rate of spontaneous recovery from doxacurium as indicated by the time for twitch height to recover from 0 to 5%, 5 to 10% and 10 to 25%, was not significantly different in the two groups. Antagonism of doxacurium was achieved more reliably with neostigmine than with edrophonium in both groups. The administration of doxacurium was associated with minimal cardiovascular effects.

Phase I Study of Stereotactic Body Radiotherapy plus Nivolumab and Urelumab or Cabiralizumab in Advanced Solid Tumors

PURPOSE

CD137 agonism and CSF1R blockade augment stereotactic body radiotherapy (SBRT) and anti-programmed death-1 in preclinical models. We evaluated the safety and efficacy of SBRT with nivolumab+urelumab (CD137 agonist) or nivolumab+cabiralizumab (CSF1R inhibitor).

PATIENTS AND METHODS

This phase I clinical trial enrolled patients with advanced solid tumors that had progressed on standard therapies. SBRT was delivered to 1-4 metastases with nivolumab+urelumab or nivolumab+cabiralizumab given concurrently and following SBRT. Dose-limiting toxicity (DLT) was the primary endpoint with anatomic location-specific SBRT doses deemed safe if ≤33% DLT frequency was observed. Secondary endpoints included RECISTv1.1 response, progression-free survival (PFS), overall survival (OS), and molecular correlative studies.

RESULTS

Sixty patients were enrolled, and median follow-up for living patients is 13.8 months. Of these, 23 (38%) received SBRT+nivolumab+urelumab and 37 (62%) received SBRT+nivolumab+cabiralizumab. Seven patients (12%) experienced a DLT (n = 3 grade 3, n = 4 grade 4) in the following anatomic cohorts: abdominal/pelvic (3/17, 18%), liver (1/13, 8%), central lung (2/14, 14%), and peripheral lung (1/12, 8%). Of 41 patients radiographically evaluable for best overall response including 55 radiated and 23 unirradiated RECIST target lesions, 2 had complete responses (5%), 7 had partial responses (17%), 12 had stable disease (29%), and 20 had progression (49%). Median estimated PFS and OS are 3.0 months [95% confidence interval (CI), 2.9-4.8] and 17.0 months (95% CI, 6.8-undetermined), respectively. No patients with elevated pre-SBRT serum IL8 experienced a response.

CONCLUSIONS

SBRT to ≤4 sites with nivolumab+urelumab or nivolumab+cabiralizumab for treating advanced solid tumors is feasible with acceptable toxicity and modest antitumor activity.See related commentary by Rodriguez-Ruiz et al., p. 5443.

Alliance A091103 a phase II study of the angiopoietin 1 and 2 peptibody trebananib for the treatment of angiosarcoma

INTRODUCTION

Angiosarcomas are rare malignant endothelial cell tumors which have up-regulation of the angiopoietin system [e.g., Tie2 and Angiopoietin 2 (Ang2)]. Trebananib is a novel agent targeting Angiopoietin 1 and Angiopoietin 2.

METHODS

Trebananib 30 mg/kg was administered weekly until progressive disease or unacceptable toxicity. The primary endpoint was response rate by RECIST v1.1. Correlatives included: (1) baseline tumor expression of Ang2/Tie2 by immunohistochemistry, (2) serum levels of Ang1 and Ang2, (3) pre- and post-treatment phospho-receptor tyrosine kinase and (4) MYC/FLT-4 amplification status.

RESULTS

Sixteen patients were enrolled [median age 68 years (24-91), 38 % male, median number of prior therapies 2.5 (1-7)]. No responses were observed in 12 evaluable patients. Estimated median and 12-week progression-free survival rate were 7 weeks (95 % 6-8) and 25 % (95 % CI 11-58 %), respectively. Median overall survival was 28 weeks (95 % CI 17-48). There were two (12.5 %) patients who experienced grade 3 adverse event and one (6.3 %) patient who experienced grade 4 adverse event that was considered at least possibly related to treatment.

CONCLUSIONS

Trebananib was well tolerated. Lack of response in the first stage of a Simon 2 stage design led to closure of this study. Prolonged PFS was observed in four pts, lasting 3.4-5.5 months.

Clinical and molecular features of innate and acquired resistance to anti-PD-1/PD-L1 therapy in lung cancer

Hypothesis

The majority of non-small cell lung cancer (NSCLC) patients treated with anti-PD-1/PD-L1 therapy develop either innate or acquired resistance. Across tumor types, the “T cell-inflamed” tumor microenvironment correlates with clinical response to immunotherapy. We hypothesize that clinical characteristics may be predictive of resistance and that “T cell-inflamed” NSCLC tumors can be identified by gene expression profiling.

Results

Of 93 patients, 36 (38.7%) had innate resistance and 57 (61.3%) had initial benefit to immunotherapy. Innate resistance was associated with non-smokers (p = 0.013), more involved disease sites (p = 0.011), more prior therapy (p = 0.001), and a lower albumin level (p = 0.014). Among patients with initial benefit, factors associated with subsequent progression-free survival included higher Karnofsky Performance Status (KPS) (p = 0.004) and lower depth of response to anti-PD-1 therapy (p = 0.003). A “T cell-inflamed” microenvironment was identified in 42% of TCGA adenocarcinoma samples versus 21.0% of squamous cell.

Discussion

Specific clinical characteristics appear to be predictive of either innate or acquired resistance to anti-PD-1/PD-L1 therapy. A “T cell-inflamed” tumor was more common in adenocarcinoma than squamous histology.

Methods

A retrospective review of NSCLC patients treated with anti-PD-1/PD-L1 monotherapy. Patients with innate resistance to anti-PD-1/PD-L1 therapy (defined as progression at first CT evaluation) were compared to patients with initial clinical benefit. Among those with initial clinical benefit, we identified prognostic factors for time to progression (acquired resistance) or death. To further corroborate our findings on limited numbers, immune gene expression profiling of all NSCLC samples from the TCGA database was also pursued.

A Phase Ib/II Study of Gemcitabine and Docetaxel in Combination With Pazopanib for the Neoadjuvant Treatment of Soft Tissue Sarcomas

LESSONS LEARNED

Our results highlight some of the challenges in the management of soft tissue sarcomas, which requires close cooperation between surgeons and medical oncologists and a careful selection of patients. The incidence of hepatotoxicity was a concerning finding and had been previously reported in patients treated with pazopanib.Although pharmacokinetic analysis was not part of this study, concomitant treatment with pazopanib has been recently reported to increase docetaxel exposure, which may explain the increased toxicity of combination regimens. It remains possible that lower doses of combined gemcitabine, docetaxel, and pazopanib may be tolerable. However, caution should be exercised in future trials investigating similar combinations.

BACKGROUND

For extremity soft tissue sarcomas (STS), surgical resection remains the standard of care, and the addition of chemotherapy is controversial. This was a phase Ib/II trial of neoadjuvant therapy for patients with STS.

METHODS

Patients with high grade, extremity STS of >8 cm and amenable to definitive resection were treated with up to four 21-day cycles of 900 mg/m(2) gemcitabine on days 1 and 8, 75 mg/m(2) docetaxel on day 8, and 400 mg of pazopanib daily (GDP), followed by surgery and, if indicated, radiation therapy. Primary and secondary endpoints (phase Ib portion) were the safety and rate of pathologic response.

RESULTS

The trial was discontinued because of slow accrual after inclusion of five patients (leiomyosarcoma: two; undifferentiated pleomorphic sarcoma: three). Two patients completed four treatment cycles: one underwent surgery and one had insufficient response and received additional therapies. Three patients discontinued treatment because of toxicity. Grade 3 adverse events included hypertension, fatigue, aspartate aminotransferase (AST) or alanine aminotransferase (ALT) elevation, hoarseness, and myelotoxicity. There were no complete or partial responses. One patient had ≥ 90% pathologic response. Among four patients who underwent resection, three remain free of disease, and one patient eventually relapsed.

CONCLUSION

GDP combination used in the neoadjuvant setting resulted in significant toxicity; despite pathologic responses, no objective responses occurred.

Therapeutic Advancements Across Clinical Stages in Melanoma, With a Focus on Targeted Immunotherapy

Melanoma is the most fatal skin cancer. In the early stages, it can be safely treated with surgery alone. However, since 2011, there has been an important revolution in the treatment of melanoma with new effective treatments. Targeted therapy and immunotherapy with checkpoint inhibitors have changed the history of this disease. To date, more than half of advanced melanoma patients are alive at 5 years; despite this breakthrough, approximately half of the patients still do not respond to treatment. For these reasons, new therapeutic strategies are required to expand the number of patients who can benefit from immunotherapy or combination with targeted therapy. Current research aims at preventing primary and acquired resistance, which are both responsible for treatment failure in about 50% of patients. This could increase the effectiveness of available drugs and allow for the evaluation of new combinations and new targets. The main pathways and molecules under study are the IDO inhibitor, TLR9 agonist, STING, LAG-3, TIM-3, HDAC inhibitors, pegylated IL-2 (NKTR-214), GITR, and adenosine pathway inhibitors, among others (there are currently about 3000 trials that are evaluating immunotherapeutic combinations in different tumors). Other promising strategies are cancer vaccines and oncolytic viruses. Another approach is to isolate and remove immune cells (DCs, T cells, and NK cells) from the patient's blood or tumor infiltrates, add specific gene fragments, expand them in culture with growth factors, and re-inoculate into the same patient. TILs, TCR gene transfer, and CAR-T therapy follow this approach. In this article, we give an overview over the current status of melanoma therapies, the clinical rationale for choosing treatments, and the new immunotherapy approaches.

Immunogenomic determinants of tumor microenvironment correlate with superior survival in high-risk neuroblastoma

BACKGROUND

Tumor-infiltrating CD8+ T cells and neoantigens are predictors of a favorable prognosis and response to immunotherapy with checkpoint inhibitors in many types of adult cancer, but little is known about their role in pediatric malignancies. Here, we analyzed the prognostic strength of T cell-inflamed gene expression and neoantigen load in high-risk neuroblastoma. We also compared transcriptional programs in T cell-inflamed and non-T cell-inflamed high-risk neuroblastomas to investigate possible mechanisms of immune exclusion.

METHODS

A defined T cell-inflamed gene expression signature was used to categorize high-risk neuroblastomas in the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) program (n=123), and the Gabriella Miller Kids First (GMKF) program (n=48) into T cell-inflamed, non-T cell-inflamed, and intermediate groups. Associations between the T cell-inflamed and non-T cell-inflamed group, MYCN amplification, and survival were analyzed by Cox proportional hazards models. Additional survival analysis was conducted after integrating neoantigen load predicted from somatic mutations. Pathways activated in non-T cell-inflamed relative to T cell-inflamed tumors were analyzed using causal network analysis.

RESULTS

Patients with T cell-inflamed high-risk tumors showed improved overall survival compared with those with non-T cell-inflamed tumors (p<0.05), independent of MYCN amplification status, in both TARGET and GMKF cohorts. Higher neoantigen load was also associated with better event-free and overall survival (p<0.005) and was independent of the T cell-inflamed signature. Activation of MYCN, ASCL1, SOX11, and KMT2A transcriptional programs was inversely correlated with the T cell-inflamed signature in both cohorts.

CONCLUSIONS

Our results indicate that tumors from children with high-risk neuroblastoma harboring a strong T cell-inflamed signature have a more favorable clinical outcome, and neoantigen load is a prognosis predictor, independent of T cell inflammation. Strategies to target SOX11 and other signaling pathways associated with non-T cell-inflamed tumors should be pursued as potential immune-potentiating interventions.

Immune-Related Adverse Events in PD-1 Treated Melanoma and Impact Upon Anti-Tumor Efficacy: A Real World Analysis

Background

Anti-PD-1 immune checkpoint inhibitor (ICI) therapy has revolutionized the treatment of melanoma by producing durable long-term responses in a subset of patients. ICI-treated patients develop unique toxicities - immune related adverse events (irAEs) – that arise from unrestrained immune activation. The link between irAE development and clinical outcome in melanoma and other cancers is inconsistent; and little data exists on the occurrence of multiple irAEs. We sought to characterize development of single and multiple irAEs, and association of irAE(s) development with clinical variables and impact upon outcomes in advanced melanoma patients treated with anti-PD-1 ICIs.

Methods

We conducted a retrospective study of 190 patients with metastatic melanoma treated with single-agent anti-PD-1 ICI therapy between June 2014 and August 2020 at a large integrated network cancer center identified through retrospective review of pharmacy records. irAEs were graded based on the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

Results

190 patients were evaluated of whom 114 patients (60.0%) experienced ≥1 irAE, including 30 (15.8%) with grade 3/4 irAEs. The occurrence of any irAE was strongly associated with the development of investigator-assessed response to anti-PD-1 therapy (p < 0.0001); whether evaluated by current (p=0.0082) or best (p=0.0001) response. In patients with ≥2 irAEs, distinct patterns were observed. Median progression-free survival (PFS) and overall survival (OS) were greater in those with any irAE compared to those without (PFS, 28 months vs. 5 months, p < 0.0001; OS, not reached vs. 9 months, p < 0.0001). Development of ≥2 irAEs had a trend towards improved PFS and OS compared to those who developed a single irAE, although this did not reach statistical significance (p=0.2555, PFS; p=0.0583, OS). Obesity but not age or gender was distinctly associated with irAE development.

Conclusions

In this study, we demonstrated that irAE occurrence was significantly associated with response to anti-PD-1 therapy and improved PFS/OS. Those who developed multiple irAEs had a trend towards improved PFS and OS compared to those who developed only a single irAE. Increased BMI but neither age nor gender were associated with irAE development. Distinct patterns of irAEs observed suggest shared etiopathogenetic mechanisms.

Single dose denileukin diftitox does not enhance vaccine-induced T cell responses or effectively deplete Tregs in advanced melanoma: immune monitoring and clinical results of a randomized phase II trial

Background

Depletion of CD25⁺ Tregs improves anti-tumor immunity in preclinical models. Denileukin diftitox is a recombinant fusion protein of human IL-2 and diptheria toxin fragment that also can kill CD25⁺ T cells. Prior clinical trials of denileukin diftitox suggested reduction of FoxP3⁺ Tregs and some clinical responses.

Method

To investigate the immunologic effects of denileukin difitox on vaccine-specific immune responses in melanoma, a randomized clinical trial of single dose denileukin diftitox prior to vaccination versus vaccination alone in subjects with HLA-A2⁺ metastatic melanoma was performed. Treatment included randomization to a 4-peptide vaccine (Melan-A, gp100, MAGE3 and NA17 with GM-CSF emulsified in Montanide) alone or after single dose of denileukin diftitox (18 mcg/kg). Vaccine was given every 2 weeks for 3 doses and, absent clinical progression, continued every 2 weeks. Blood and tumor biopsies were obtained pretreatment and after 3 vaccinations for immunologic assessments.

Results

In 17 treated subjects there were no drug-related G3-4 adverse events. One partial response and 8 stable disease were observed in 9 subjects (4 DD: 5 vaccine only) with no impact of denileukin diftitox on time to progression. Total peripheral Tregs were not significantly altered, and in 1 patient biopsy intra-tumoral FoxP3 transcripts were not reduced following denileukin diftitox. ELISA for IL2R-α demonstrated no impact on outcomes by soluble CD25 level. Immune monitoring suggested the development of modest vaccine-specific CD8⁺ T cell responses in the control group, however immunization efficacy was actually reduced in the denileukin diftitox group.

Conclusion

Our results indicate that denileukin diftitox did not effectively deplete Tregs, augment T cell responses, or improve clinical activity in melanoma. Clinicaltrials.gov ID: NCT00515528; Registered August 9, 2007.

A phase I, first-in-human, open-label, dose-escalation study of MGD013, a bispecific DART molecule binding PD-1 and LAG-3, in patients with unresectable or metastatic neoplasms

3004

Background: MGD013 is an investigational, first-in-class, Fc-bearing bispecific tetravalent DART molecule designed to bind PD-1 and LAG-3 and sustain/restore the function of exhausted T cells. MGD013 demonstrates ligand blocking properties consistent with anti-PD-1 and anti-LAG-3 benchmark molecules, and improves T cell responses beyond that observed with benchmark or component antibodies alone or in combination. Methods: This study characterizes the safety, tolerability, dose-limiting toxicities, maximum tolerated dose (MTD), PK/PD, and antitumor activity of MGD013 in patients (pts) with advanced solid and hematologic malignancies. Sequential single-pt cohorts were treated with escalating flat doses of MGD013 (1-1200 mg IV every 2 weeks), followed by a 3+3 design. Tumor-specific expansion cohorts are being treated at the recommended Phase 2 dose of 600 mg. Results: At data-cutoff, 50 pts (46% checkpoint-experienced) were treated in Dose Escalation, and 157 pts (32% checkpoint-experienced) in Cohort Expansion. No MTD was defined. Treatment-related adverse events (TRAEs) occurred in 146/207 (70.5%) pts, most commonly fatigue (19%) and nausea (11%). The rate of Grade ≥ 3 TRAEs was 23.2%. Immune-related AEs were consistent with events observed with anti-PD-1 antibodies. Mean half-life was 11 days; peripheral blood flow cytometry analyses confirmed full and sustained on-target binding during treatment at doses ≥ 120 mg. Among 41 response-evaluable [RE] dose escalation pts, 3 confirmed partial responses [cPRs] (triple negative breast cancer [TNBC], mesothelioma, gastric cancer) per RECIST 1.1 were observed, while 21 pts had stable disease [SD]. Among select expansion cohorts, PRs have been observed in epithelial ovarian cancer (n=2; both cPRs, and 7 with SD among 15 RE pts) and TNBC (n=2; 1 cPR, 1 unconfirmed PR [uPR], and 5 with SD among 14 RE pts). In a cohort of pts with HER2+ tumors treated with MGD013 in combination with margetuximab (investigational anti-HER-2 antibody), 3 PRs have been observed (breast [n=2], colorectal [n=1]; 1 cPR, 2 uPRs) and 2 pts with SD among 6 RE pts. Objective responses have been observed in several pts after prior anti-PD-1 therapy. Investigations into potential correlative biomarkers including LAG-3 and PD-1 are ongoing. Conclusions: MGD013, a novel molecule designed to coordinately block PD-1 and LAG-3, has demonstrated an acceptable safety profile and encouraging early evidence of anti-tumor activity. Clinical trial information: NCT03219268 .

Single Institution Experience of Ipilimumab 3 mg/kg with Sargramostim (GM-CSF) in Metastatic Melanoma

Ipilimumab, 10 mg/kg with sargramostim (GM-CSF; GM), improved overall survival (OS) and safety of patients with advanced melanoma over ipilimumab in a randomized phase II trial. The FDA-approved dose of ipilimumab of 3 mg/kg has not been assessed with GM (IPI-GM). Consecutive patients treated with IPI-GM at a single institution were reviewed. Treatment included ipilimumab every 3 weeks × 4 and GM, 250-μg s.c. injection days 1 to 14 of each ipilimumab cycle. Efficacy, clinical characteristics, toxicities, and blinded radiology review of tumor burden were evaluated. Thirty-two patients were identified with 25 (78%) having immune-related response criteria (irRC) measurable disease and 41% with central nervous system metastases. A total of 88.6% of GM doses were administered. Response rate by irRC and disease control rate at 12 weeks were 20% and 44%, respectively (median follow-up 37 weeks). Immune-related adverse events (irAE) were observed in 10 (31.3%) patients, with 3 (9.4%) grade 3 events. Patients with grade 3 irAEs had prior autoimmunity, advanced age, and poor performance status. The median OS from first dose of ipilimumab was 41 weeks. Ipi-GM treatment is feasible and in this poor-risk advanced melanoma population, efficacy appeared similar but safety appeared improved relative to historical ipilimumab alone.

Significant antitumor activity for low-dose ipilimumab (IPI) with pembrolizumab (PEMBRO) immediately following progression on PD1 Ab in melanoma (MEL) in a phase II trial

10004

Background: Combination PD1 + CTLA4 antibodies (Abs) shows greater response rate (RR) versus PD1 Ab alone in MEL, but RR after initial PD1 Ab progression awaits robust investigation. CTLA4 Ab alone after PD1 Ab progression has a historical RR of 13%. We report final results of the first prospective clinical trial evaluating IPI 1mg/kg + PEMBRO immediately following progression on PD1 Ab (NCT02743819). Methods: Patients (pts) with advanced MEL, no prior CTLA4 Ab for metastatic disease, and who had progressed on PD1 Ab as immediately prior therapy (or non-CTLA4 Ab combination) were eligible. Pts received PEMBRO 200 mg + IPI 1 mg/kg Q3W for 4 doses, then PEMBRO alone for up to two years. The primary endpoint was RR by irRECIST. After 35 pts, the study met its primary endpoint with 10/22 evaluable pts achieving a response. The trial was expanded to enroll a total of 70 pts in open-label accrual to further describe the RR for this regimen in an exploratory fashion. The data analysis cutoff was January 30, 2020. Results: 67/70 accrued patients were evaluable for treatment response. Prior treatments included 60 on PD1 Ab alone and 10 on PD1 Ab-based combinations. Of these, 10 pts had progressed in the adjuvant setting. Median length of treatment on prior PD1 Ab was 4.8 months. Response assessments included 4 CR, 17 PR and 16 SD for a RR of 31% (21/67) in evaluable pts, and 30% (21/70) in all enrolled pts. 4 pts with a PR and 6 with SD had unconfirmed responses making the irRECIST response rate 25% (17/67) and 24% (17/70) among evaluable and enrolled pts, respectively. Median progression free survival (PFS) was 4.7 mo (95% CI: 2.8-8.3) and PFS at six months was 45% (95% CI: 33%-57%). 15/70 (21%) pts experienced ≥ grade 3-4 drug-related AEs, the most common being diarrhea, rash and transaminase elevation. PD-L1 positive vs negative status from historical tumor specimens did not associate with RR. Conclusions: This is the largest prospective study of IPI 1mg/kg + PEMBRO, demonstrating significant antitumor activity and tolerability in MEL post-PD1 Ab. Clinical trial information: NCT02743819.

Immune Checkpoint Inhibitors for Genitourinary Cancers: Treatment Indications, Investigational Approaches and Biomarkers

Cancers of the genitourinary (GU) tract are common malignancies in both men and women and are a major source of morbidity and mortality. Immune checkpoint inhibitors (ICI) targeting CTLA-4, PD-1 or PD-L1 have provided clinical benefit, particularly in renal cell and urothelial carcinoma, and have been incorporated into standard of care treatment in both localized and metastatic settings. However, a large fraction of patients do not derive benefit. Identification of patient and tumor-derived factors which associate with response have led to insights into mechanisms of response and resistance to ICI. Herein, we review current approvals and clinical development of ICI in GU malignancies and discuss exploratory biomarkers which aid in personalized treatment selection.

Immunobiology, preliminary safety, and efficacy of CPI-006, an anti-CD73 antibody with immune modulating activity, in a phase 1 trial in advanced cancers

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Background: CPI-006 inhibits CD73, a nucelotidase that converts AMP to adenosine and functions as a lymphocyte adhesion molecule. CPI-006 is a humanized IgG1 FcγR binding-deficient antibody that binds to CD73+ T and B lymphocytes leading to activation of B cells and expression of CD69. This study investigates the immunobiology, safety, and efficacy of CPI-006 monotherapy and in combination with CPI-444, an adenosine A2A receptor (A2AR) antagonist (NCT03454451). Methods: Patients with relapsed solid tumors were treated in a 3 + 3 escalation study with 1, 3, 6 or 12 mg/kg CPI-006 (Q3w IV infusion) monotherapy or in combination with CPI-444 (100 mg, PO, BID). Flow cytometry was performed on blood samples for lymphocyte subset analysis and receptor occupancy. Results: 17 patients were enrolled; 11 monotherapy and 6 combination. CPI-006 was associated with Grade 1 infusion reactions occuring within 30 minutes of the first infusion and were eliminated by premedication with non-steroidals. No DLTs with monotherapy or combination therapy were seen. Receptor occupancy on peripheral lymphocytes was maintained for the full dosing interval at 12 mg/kg. Pharmacodynamic effects suggesting immune modulation were observed within 1 hr of infusion at all dose levels and included a decrease in peripheral blood CD73pos B cells (mean reduction 86%, p < 0.05), increased CD73neg CD4 T cells (mean increase 37%, p < 0.01), and decreased CD8 T cells (mean reduction 20%, p < 0.01) compared to baseline. Overall, CD4:CD8 ratios were increased. Tumor regression was observed in a prostate cancer patient after 5 cycles of monotherapy at 6 mg/kg; peripheral B cells partially returned by the second cycle and reached a new homeostatic level through subsequent cycles. No change in serum immunoglobulins were observed. Conclusions: CPI-006 induces a rapid lymphocyte redistribution, including a transient reduction of circulating CD73pos B cells suggesting redistribution to lymphoid tissues, and an increased CD4:CD8 ratio, consistent with increased TH effector/memory cells in the blood. The treatment has been well-tolerated, and there is early evidence of anti-tumor activity of CPI-006 monotherapy. Clinical trial information: NCT03454451.