First-in-human study of AMG 193, an MTA-cooperative PRMT5 inhibitor, in patients with MTAP-deleted solid tumors: results from phase I dose exploration.

BACKGROUND: Homozygous deletion of methylthioadenosine phosphorylase (MTAP) occurs in ∼10%-15% of solid tumors. AMG 193, a CNS-penetrant methylthioadenosine-cooperative protein arginine methyltransferase 5 (PRMT5) inhibitor, selectively induces synthetic lethality in MTAP-deleted tumor cells. Here, we report results of the completed monotherapy dose exploration evaluating AMG 193 in patients with MTAP-deleted solid tumors. PATIENTS AND METHODS: In this first-in-human, multicenter, open-label, phase I study, patients with advanced CDKN2A-deleted and/or MTAP-deleted solid tumors received AMG 193 orally [once (o.d.) or twice (b.i.d.) daily] continuously in 28-day cycles. Primary objectives were safety and tolerability assessed by dose-limiting toxicities and determination of the maximum tolerated dose; secondary objectives included pharmacokinetics and preliminary antitumor activity measured by RECIST v1.1. RESULTS: As of 23 May 2024, 80 patients in dose exploration received AMG 193 at doses 40-1600 mg o.d. or 600 mg b.i.d. The most common treatment-related adverse events were nausea (48.8%), fatigue (31.3%), and vomiting (30.0%). Dose-limiting toxicities were reported in eight patients at doses ≥240 mg, including nausea, vomiting, fatigue, hypersensitivity reaction, and hypokalemia. The maximum tolerated dose was determined to be 1200 mg o.d. Mean exposure of AMG 193 increased in a dose-proportional manner from 40 mg to 1200 mg. Among the efficacy-assessable patients treated at the active and tolerable doses of 800 mg o.d., 1200 mg o.d., or 600 mg b.i.d. (n = 42), objective response rate was 21.4% (95% confidence interval 10.3% to 36.8%). Responses were observed across eight different tumor types, including squamous/non-squamous non-small-cell lung cancer, pancreatic adenocarcinoma, and biliary tract cancer. At doses ≥480 mg, complete intratumoral PRMT5 inhibition was confirmed in paired MTAP-deleted tumor biopsies, and molecular responses (circulating tumor DNA clearance) were observed. CONCLUSIONS: AMG 193 demonstrated a favorable safety profile without clinically significant myelosuppression. Encouraging antitumor activity across a variety of MTAP-deleted solid tumors was observed based on objective response rate and circulating tumor DNA clearance.

A phase II/III randomized study to compare the efficacy and safety of rigosertib plus gemcitabine versus gemcitabine alone in patients with previously untreated metastatic pancreatic cancer.

BACKGROUND: Rigosertib (ON 01910.Na), a first-in-class Ras mimetic and small-molecule inhibitor of multiple signaling pathways including polo-like kinase 1 (PLK1) and phosphoinositide 3-kinase (PI3K), has shown efficacy in preclinical pancreatic cancer models. In this study, rigosertib was assessed in combination with gemcitabine in patients with treatment-naïve metastatic pancreatic adenocarcinoma. MATERIALS AND METHODS: Patients with metastatic pancreatic adenocarcinoma were randomized in a 2:1 fashion to gemcitabine 1000 mg/m(2) weekly for 3 weeks of a 4-week cycle plus rigosertib 1800 mg/m(2) via 2-h continuous IV infusions given twice weekly for 3 weeks of a 4-week cycle (RIG + GEM) versus gemcitabine 1000 mg/m(2) weekly for 3 weeks in a 4-week cycle (GEM). RESULTS: A total of 160 patients were enrolled globally and randomly assigned to RIG + GEM (106 patients) or GEM (54). The most common grade 3 or higher adverse events were neutropenia (8% in the RIG + GEM group versus 6% in the GEM group), hyponatremia (17% versus 4%), and anemia (8% versus 4%). The median overall survival was 6.1 months for RIG + GEM versus 6.4 months for GEM [hazard ratio (HR), 1.24; 95% confidence interval (CI) 0.85-1.81]. The median progression-free survival was 3.4 months for both groups (HR = 0.96; 95% CI 0.68-1.36). The partial response rate was 19% versus 13% for RIG + GEM versus GEM, respectively. Of 64 tumor samples sent for molecular analysis, 47 were adequate for multiplex genetic testing and 41 were positive for mutations. The majority of cases had KRAS gene mutations (40 cases). Other mutations detected included TP53 (13 cases) and PIK3CA (1 case). No correlation between mutational status and efficacy was detected. CONCLUSIONS: The combination of RIG + GEM failed to demonstrate an improvement in survival or response compared with GEM in patients with metastatic pancreatic adenocarcinoma. Rigosertib showed a similar safety profile to that seen in previous trials using the IV formulation.

Diabetes mellitus affects response to neoadjuvant chemoradiotherapy in the management of rectal cancer.

INTRODUCTION: Although diabetic patients with rectal cancer have poorer outcomes than their nondiabetic counterparts, few studies have looked at diabetics' response to therapy as an explanation for this disparity. This study compares the neoadjuvant chemoradiotherapy (CRT) response in diabetic and nondiabetic patients with locally advanced rectal cancers. METHODS: This is a single-institution, retrospective review of rectal cancer patients who received CRT followed by resection from 1995 to 2006. Pretreatment tumor-node-metastasis (TNM) staging was determined using endorectal ultrasound, computed tomography (CT) scan, and magnetic resonance imaging (MRI); post-treatment staging was determined by pathological review. RESULTS: 110 patients were included; seventeen had diabetes and 93 were nondiabetics. Pretreatment staging was similar in both groups. Sixteen of the diabetics (94%) completed CRT compared to 92% (86/93) of the nondiabetics. Tumor downstaging rates were similar in the two groups (53% in diabetics, 52% in nondiabetics). Nondiabetic patients had a higher rate of nodal downstaging although not statistically significant (67% versus 27%, P = 0.80). While none of the diabetics patients achieved a pathologic complete response (pCR), 23% (21/93) of the nondiabetics did (P = 0.039). Local progression rates were higher in the diabetic group (24% versus 5%, P = 0.046). CONCLUSION: Our study shows that neoadjuvant chemoradiotherapy in rectal cancer is less effective in diabetic patients than in nondiabetics. While minimal differences are found in the rate of downstaging, the rate of achieving a complete pathologic response was significantly higher in nondiabetic patients, and in fact was not seen in any of our diabetic patients. This may explain the poorer outcomes seen in diabetic patients with rectal cancer.

Detection of shared MHC-restricted human melanoma antigens after vaccinia virus-mediated transduction of genes coding for HLA.

To detect shared human melanoma Ag that are recognized by HLA-A2 restricted, melanoma-specific CTL derived from tumor infiltrating lymphocytes, we have developed a convenient method to insert and express foreign HLA genes capable of presenting Ag on target cell lines. Seventeen melanoma cell lines and 11 nonmelanoma cell lines were infected with recombinant vaccinia virus containing the HLA-A2.1 gene. Infection by the vaccinia virus resulted in expression of functional HLA-A2 molecules on the cell surface of virtually 100% of infected cells within a 3.5-h period. The results showed that 11 of 17 (65%) naturally HLA-A2- melanoma cell lines were specifically lysed by the HLA-A2-restricted, melanoma-specific TIL after infection with the vaccinia-HLA-A2.1 virus. None of the nine human nonmelanoma cell lines tested (three colon cancer, four breast cancer, or two immortalized non-tumor cell lines) or two murine melanoma cell lines were lysed by the HLA-A2-restricted TIL after vaccinia-HLA-A2.1 infection. Coinfection of the vaccinia virus containing the beta 2-microglobulin gene with the vaccinia-HLA-A2.1 virus increased the surface expression of HLA-A2 and subsequent lysis by melanoma-specific tumor infiltrating lymphocytes. With this new method we could extend previous findings demonstrating that shared melanoma Ag recognized by HLA-A2-restricted tumor infiltrating lymphocytes exist among melanoma cells from different patients regardless of HLA type. These Ag represent excellent candidates for the development of vaccines to induce T cell responses for the immunotherapy of patients with melanoma.

T-cell recognition of human melanoma antigens.

The adoptive transfer of tumor-infiltrating lymphocytes (TILs) with interleukin-2 (IL-2) has antitumor activity in some patients with metastatic melanoma. We have analyzed molecular mechanisms of TIL recognition of human melanoma. Some cultured TILs specifically lysed autologous and some allogeneic melanomas sharing a variety of class I major histocompatibility complex (MHC) molecules. HLA-A2-restricted melanoma-specific TILs lysed many HLA-A2+ melanoma cell lines from different patients but failed to lyse HLA-A2- melanoma and HLA-A2+ nonmelanoma cell lines. However, these TILs were capable of lysing many naturally HLA-A2- melanomas after introduction of the HLA-A2.1 gene by vaccinia virus. These results indicate that shared melanoma antigens (Ag) are expressed in melanomas regardless of their human leukocyte antigen types. In order to identify these shared melanoma Ags, we have tested some known proteins expressed in melanoma. Expression of tyrosinase or HMB45 Ag correlated with lysis of TILs. We are also attempting to isolate antigenic peptides by high performance liquid chromatography separation and genes encoding melanoma Ag by cDNA expression cloning. The T-cell component of the antimelanoma response was also analyzed by determining the genetic structure of the T-cell receptor (TCR) used by melanoma TILs. However, we did not observe common TCR variable region usage by different melanoma TILs. We could establish melanoma cell clones and lines resistant to TIL lysis due to the absence of or defects in the expression of Ag, MHC, or beta 2-microglobulin molecules. These data indicate multiple mechanisms for melanoma escape from T-cell immunosurveillance.(ABSTRACT TRUNCATED AT 250 WORDS)