Anti-CTLA-4 probody BMS-986249 alone or in combination with nivolumab in patients with advanced cancers: Initial phase I results

3058

Background: Blockade of the CTLA-4 pathway with ipilimumab (IPI) ± nivolumab (NIVO; anti–PD-1) is an effective treatment for a variety of cancers. To optimize the risk-benefit profile of CTLA-4–directed therapy, a Probody therapeutic technology platform (Pb-Tx, CytomX Therapeutics) was used to generate BMS-986249, a peptide-masked version of IPI that is unmasked by tumor-associated proteases. Pb-Tx may localize CTLA-4 activity to the tumor, minimize systemic toxicity, and allow for higher doses of anti–CTLA-4 ± anti-PD-1. In preclinical studies, BMS-986249, given at similar doses, showed comparable intratumoral and reduced peripheral pharmacodynamic activity relative to IPI (Engelhardt, AACR 2020). Here, we present the initial results of the first-in-human phase 1/2 study of BMS-986249 ± NIVO in pts with advanced (adv) cancers (NCT03369223). Methods: During dose escalation, pts received BMS-986249 at or above the approved doses of the parent molecule using a Q4W or Q8W dosing schedule as monotherapy (240–2400 mg Q4W or 1600 mg Q8W; ≈ 3–30 mg/kg vs approved 3 mg/kg Q3W IPI) or in combination (240–1200 mg Q4W or 800 mg Q8W) + NIVO 480 mg Q4W. Safety and pharmacokinetics (PK) were evaluated. Efficacy is being assessed in the dose-expansion phase. Results: As of December 7, 2019, 82 anti–CTLA-4 naive pts with various adv cancers received BMS-986249 ± NIVO (mono, n = 39; combo, n = 43). Median age 60 (25–78) y; 95% pts had prior systemic therapy. TRAEs occurred in 59% of pts (Gr 3/4, 23%) with mono and 74% of pts (Gr 3/4, 30%) with combo. Diarrhea was the most common any-Gr TRAE (mono, 23%; combo, 21%) and Gr 3/4 TRAE (mono, 15%; combo, 7%). Rates of Gr 3/4 TRAEs increased with higher doses of BMS-986249 but were substantially reduced with Q8W schedule (eg, 800 mg Q4W, 18%; 1600 mg Q4W, 60%; 1600 mg Q8W, 9%). Most TRAEs resolved, no Gr 5 TRAEs occurred. The peptide-masked intact probody accounted for most (73%) of the systemic BMS-986249-related species; elimination of the probody indicated involvement of both catabolism and cleavage processes. Conclusions: BMS-986249 ± NIVO displayed a clinically manageable safety profile, allowing assessment of comparably higher BMS-986249 dose intensity (240-1200 mg; ≈ 3-15 mg/kg) + NIVO (480 mg Q4W, full dose) than that tested with IPI + NIVO. The types of TRAEs were consistent with CTLA-4 blockade, and the overall data align with the proposed Pb-Tx mechanism of action. The preclinical and clinical data support the ongoing randomized BMS-986249 + NIVO expansion in pts with adv melanoma, in addition to other adv tumors. Clinical trial information: NCT03369223 .

Intratumoral (i.t.) IMO-2125 (IMO), a TLR9 agonist, in combination with ipilimumab (ipi) in PD-(L)1 refractory melanoma (RM)

136

Background: Checkpoint inhibitors (CPI) have transformed melanoma treatment but many patients remain refractory. CPI plus i.t. IMO may improve response by activating innate immune function. Based on this we initiated a trial of IMO in combination with ipi or pembrolizumab (pem) in RM. Methods: Adults with RM that progressed during or after ≥ 12 weeks of PD-1 therapy are eligible. IMO, 4 – 32 mg, is given i.t. for 6 doses, along with either ipi or pem. Endpoints are safety, response, biomarkers, and PK. Injected and distant tumors are biopsied pre-treatment and again at 24 hrs (injected tumor), weeks 8 and 13 for immune analyses. Results: As of October 7, 2016, 10 pts have been treated; median age 55 (range: 39-76), 8 with visceral and 1 with brain metastases. Two pts have mucosal histology. 60% have BRAF mutations. Prior duration of anti-PD-(L)1 therapy ranges from 8 to 63 weeks and median time from last PD-1 therapy to onset of study treatment is 6 (4,57) weeks. IMO has been administered at 4, 8, and 16 mg. No DLTs have been observed and there have been no treatment-related discontinuations or deaths. Ipi was discontinued after the second dose in one subject with previous ipi-related hepatitis for recurrent transaminase elevations (grade 4). Grade 3 hypophysitis is the only other immune-related AE (2 pts). Most frequent TEAE (N > 2) are nausea, vomiting, anemia, diarrhea, increases in ALT/AST/GGT/triglycerides, chills, fatigue, pyrexia, and leukopenia; the majority are low-grade. 6 patients are evaluable for response - CR (1), PR (2), SD (2), PD (1) by RECIST1.1. Tumor biopsies show consistent maturation of the myeloid DC1 subset in IMO injected tumors at 24 hrs. Week 8 results are consistent with a higher rate of proliferative (Ki67) effector CD4+ and CD8+ T-cells in responders. Circulating IFNγ shows 2-3 fold increase in responders. Conclusions: The combination of IMO and ipi is tolerable and has activity in PD-1 refractory melanoma. Dose escalation is ongoing and a Phase 2 expansion with both combinations is planned. Updated safety, antitumor activity, PK, and biomarker data will be presented at the meeting. Clinical trial information: NCT02644967.

Retrospective study of non-mucinous appendiceal adenocarcinomas: Role of systemic chemotherapy and cytoreductive surgery

263

Background: The majority of studies evaluating appendiceal epithelial neoplasms have focused on those with mucinous histology. Few studies have reported on non-mucinous appendiceal adenocarcinomas. We performed the largest single-center study to investigate this histologic subtype, in order to describe the natural history and impact of both cytoreductive surgery (CRS) and systemic chemotherapy. Methods: We retrospectively reviewed 172 pts with non-mucinous appendiceal adenocarcinoma evaluated at the UT-MD Anderson Cancer Center between 1990 and 2015. Patient demographics, tumor characteristics, therapy received, and outcomes were recorded. Response assessment was semi-quantitative (response vs. no response) according to the treating physician. Overall survival (OS) and time to progression (TTP) were calculated using Kaplan Meier product-limit method and survival rates compared using the log rank test. Results: Median age at diagnosis was 52.9 yrs (M:F 1:1). Most pts presented with advanced stage: stage I (1.7%), stage II (32.5%), stage III (14.5%), and stage IV (51.2%). No patient had well-differentiated histology. 56% had moderate and 44% poor histology. Median OS by stage was 90.9m [95% CI: 70.8 to 172.9] for stage II, 52.1m [95% CI: 28.9 to NA] for stage III and 28.3m [95% CI: 22.9 to 31.9] for stage IV, (p < 0.0001). In pts with metastatic disease (n = 128) CRS was attempted in 20 (15.6%) and was complete (CCS 0/1) in 12. The median OS for pts achieving complete CRS was 48.6m. Systemic chemotherapy was administered to 92% (118/128) of metastatic pts. The median TTP was 9.4m [95% CI: 8.0 to 11.5] and semi-quantitative response rate was 54%. The majority of pts received either oxaliplatin-based, 57%, or irinotecan-based, 23%, first-line chemotherapy regimens. No statistical difference in TTP (p = 0.9) or OS (p = 0.07) between different chemotherapies was seen. Conclusions: In contrast to mucinous appendiceal neoplasms, non-mucinous appendiceal adenocarcinomas rarely present with low-grade (well-differentiated) histology. Treatment approaches appear more akin to colorectal cancer with most metastatic pts undergoing systemic chemotherapy and a minority undergoing CRS.