Low dose meloxicam is safe and tolerable when combined with toceranib phosphate in cancer-bearing cats

Objectives Non-steroidal anti-inflammatory drugs (NSAIDs) are infrequently utilized in cats due to concern for renal compromise; however, recent studies demonstrate tolerability of low dose meloxicam. Toceranib phosphate is used to treat several feline cancers and is well tolerated. This study aimed to determine the tolerability and adverse event profile of combined toceranib and low dose meloxicam in cancer-bearing cats. Secondary goals involved assessing anticancer tumor efficacy and impact upon quality of life and analgesia. Methods Cats with any cancer not involving the kidneys were eligible. The study adopted a conventional 3 + 3 dose escalation design. Toceranib was administered every other day at a standard dose with meloxicam administered in an escalating fashion in subsequent cohorts, at a starting dose of 0.01 mg/kg on opposite days to toceranib, up to a maximum of 0.02 mg/kg daily, based upon previous safety studies. Laboratory work, blood pressure, tumor measurements, pain score and client-completed quality-of-life surveys were recorded every 2–4 weeks during the 12-week study period. Results Twenty-one cats were enrolled. When combined with toceranib, a meloxicam dose of 0.02 mg/kg q24h was safe and well tolerated, with no cats being withdrawn due to adverse events from the drug combination. The majority of cats demonstrated clinical benefit with stable to mildly improved tumor measurements, quality of life and pain scores. Conclusions and relevance Low dose meloxicam combined with toceranib is safe and well tolerated in cancer-bearing cats. Continued patient recruitment and data collection are needed to determine the maximum tolerated dose of meloxicam. The results of our study will guide further phase II/III trials.

257 Combination of adenosine antagonists A2AR (TT-10) and A2BR (TT-4) with checkpoint inhibitors demonstrate anti-tumor activity in CT-26 murine colon tumor allograft model

BackgroundTT-10 and TT-4 are potent and selective antagonists of adenosine A2A receptor (A2AR) and A2B receptor (A2BR) respectively. Both agents are being developed for the treatment of advanced cancers initially as monotherapy, using high levels of adenosine receptor expression in tumor tissue as biomarker.MethodsBalb/c mice were implanted with CT-26 cells and randomly assigned to 8 groups per study; (1) vehicle control, (2) adenosine antagonist - 1 mg/kg A2AR (TT-10) 1 mg/kg or 3 mg/kg A2BR (TT-4), (3) 10 mg/kg Anti-mPD-1, (4) 5 mg/kg Anti-mCTLA-4, (5) 100 mg/kg Irinotecan, (6) adenosine antagonist + Anti-mPD-1, (7) adenosine antagonist + Anti-mCTLA-4, (8) adenosine antagonist+ Irinotecan. Adenosine antagonists and control were given daily by oral gavage, Anti-mPD-1, Anti-mCTLA-4 and Irinotecan were administered Intraperitoneal. Treatment was started on day 1 post implant and mice were followed until individual tumor volume reached 2,000 or 3000 mm3 (as defined by protocol) or moribund. Tumor measurements and weights were taken every 2 to 3 days. In addition, a subset of mice were investigated for changes in peripheral whole blood and intra-tumor analysis on days 3 and 10 via flow cytometry. The populations of interest included CD223+, CD3+, CD4+, CD8+, CD25+FoxP3+, CD25-CD69+ and CD44+CD62L.ResultsAll implanted mice developed measurable tumors. Mean suppression of tumor growth was observed to be greater in single agent adenosine antagonists TT-10 and TT-4 when compared to the vehicle control and was observed to show overall greater suppression of tumor growth when combined with anti-mPD-1 or anti-m-CTLA-4. Tumor infiltrating lymphocyte analysis by flow cytometry, showed higher amounts of CD25+FoxP3+ present in control mice at day 3, than was observed in mice that were treated with A2AR alone, A2AR + anti-mPD-1 and A2AR + anti-m-CTLA-4.ConclusionsTT-10 and TT-4 alone was superior to vehicle control in slowing tumor growth. However, the combination of TT-10 + Anti-mPD-1 and TT-4 + Anti-mCTLA-4 showed the greatest tumor response and growth suppression. Furthermore, a striking reduction of CD25+FoxP3+ within the tumor was observed at day 3 in mice treated with A2AR alone, A2AR + anti-mPD-1 and A2AR + anti-m-CTLA-4 when compared to the vehicle control.

Extent of radiological response does not reflect survival in primary central nervous system lymphoma

Background In primary central nervous system lymphoma (PCNSL), small enhancing lesions can persist after treatment. It is unknown whether a difference in response category (complete response [CR], complete response unconfirmed [CRu], or partial response [PR]) reflects survival. We aimed to determine the value of a central radiology review on response assessment and whether the extent of response influenced progression-free and/or overall survival. Methods All patients in the HOVON 105/ALLG NHL 24 study with at least a baseline MRI and one MRI made for response evaluation available for central review were included. Tumor measurements were done by 2 independent central reviewers, disagreements were adjudicated by a third reviewer. Crude agreement and interobserver agreement (Cohen's kappa) were calculated. Differences in progression-free and overall survival between different categories of response at the end-of-protocol-treatment were assessed by the log-rank test in a landmark survival-analysis. Results Agreement between the central reviewers was 61.7% and between local and central response assessment was 63.0%. Cohen's kappa's, which corrects for expected agreement, were 0.44 and 0.46 (moderate), respectively. Progression agreement or not was 93.3% (kappa 0.87) between local and central response assessment. There were no significant differences in progression-free and overall survival between patients with CR, CRu, or PR at the end-of-protocol-treatment, according to both local and central response assessment. Conclusions Reliability of response assessment (CR/CRu/PR) is moderate even by central radiology review and these response categories do not reliably predict survival. Therefore, primary outcome in PCNSL studies should be survival rather than CR or CR/CRu-rate.

208 E7777 (denileukin diftitox) enhances anti-tumor activity and significantly extends survival benefit of anti-PD-1 in syngeneic solid tumor models

BackgroundRegulatory T cell (Tregs) inhibit activity of anti-tumor T cells, and have been shown to limit checkpoint inhibitor effectiveness. Depletion of Tregs seems desirable during immunotherapy, but chronic Treg depletion with antibody therapies can lead to serious autoimmune adverse events. Compared to antibodies, the fusion protein E7777 (IL-2/diphtheria toxin) has a relatively short half-life in circulation, which allows for transient and selective Treg depletion. The potential therapeutic benefit of combining E7777 with anti-PD-1 was tested in syngeneic solid tumor models.MethodsCT26 colon and H22 liver cancer tumors were implanted subcutaneously in immunocompetent BALB/c mice. E7777 (2.5 mcg/mouse, i.v.) was given on a Q7Dx3 schedule. Anti-murine PD-1 was given (100 mcg/mouse, i.v.) Q4Dx5. Groups of 16 mice received each agent as monotherapy or in combinations. Sequencing of combination administration was also varied: Group 4 started treatment on the same day; Group 5 received E7777 2 days prior to start of anti-PD-1; Group 6 received anti-PD-1 first. Tumor growth was compared across all groups. In survival studies, mice were treated for 3 weeks and observed with twice weekly tumor measurements. In other experiments, tumors, tumor-draining lymph nodes, and spleens were examined by IHC and by flow cytometry of immune cells from dissociated tissues at defined points, for immune biomarkers.ResultsFigure 1 shows additive benefit from the E7777 + anti-PD-1 combinations over either monotherapy. Most importantly, figure 2 and table 1 show significantly enhanced overall survival from a 3 week course of combinations compared to either agent alone (p<0.005) or to vehicle controls (p<0.000001). There was no clear distinction among different sequencing regimens. Benefit correlated with enhanced CD8:Treg ratios in tumors.Abstract 208 Figure 1Tumor growth in s.c. syngeneic solid tumors. N=16/groupAbstract 208 Figure 2Overall survival in s.c. syngeneic models. N=16/groupAbstract 208 Table 1Calculated median survivalConclusionsDepletion of Tregs by E7777 significantly increased anti-tumor activity and durably extended overall survival compared to treatment with anti-PD-1 alone in syngeneic solid tumor models. Clinical studies of a combination of the two agents are planned.Ethics ApprovalAll studies were conducted at Crown Bio, and were approved by the Crown Bio IACUC.

NIMG-28. VALIDATION OF MODIFIED RESPONSE ASSESSMENT IN NEURO ONCOLOGY (mRANO) DETERMINED PFS AS A STRONG PREDICTOR OF OVERALL SURVIVAL IN RECURRENT GLIOBLASTOMA TREATED WITH A TARGETED IMMUNOTOXIN

INTRODUCTION The current study compared the modified response assessment in neuro-oncology (mRANO)(1), iRANO (2), and standard RANO criteria (3) as well as quantified the association between progression-free (PFS) and overall survival (OS) in an immunotherapy trial in recurrent glioblastoma (rGBM). METHODS A total of 47 patients with rGBM were enrolled in a phase II convection-enhanced delivery of an IL4R-targeted immunotoxin (MDNA55-05, NCT02858895). Bidirectional tumor measurements were created by local sites and an independent radiologic faculty (IRF), then standard RANO, iRANO, and mRANO criteria were applied. Differences of PFS and the association between PFS and OS were evaluated. RESULTS 41 of 47 patients were evaluable for response. Both local site and IRF-determined PFS was significantly shorter using standard RANO compared to iRANO (log-rank, P&lt; 0.0001; HR=0.3) and mRANO (P&lt; 0.0001; HR=0.3). No difference in PFS was observed between iRANO and mRANO (Local, P=0.67; IRF, P=0.59). In patients who died and had confirmed progression on standard RANO, no correlation was observed between PFS and OS (Local, P=0.47; IRF, P=0.34). Using the iRANO, a weak association driven by a few outliers was observed between confirmed PFS and OS via local site measurements (P=0.017), but not central IRF measurements (P=0.18). Importantly, 24 of 41 patients (59%) were censored using iRANO and not included because they did not have confirmation of progression 3 months after initial progression. A strong correlation was observed between mRANO PFS and OS for both local (R2=0.66, P&lt; 0.0001) and IRF-determined reads (R2=0.57, P=0.0007). CONCLUSION No correlation between PFS and OS was observed for standard RANO or iRANO, but a strong correlation was identified between both locally-determined and centrally-determined PFS and OS using the mRANO criteria. Also, the iRANO criteria was difficult to implement due to need to confirm progression 3 months after initial progression, censoring more than half the patients.

An FDA analysis of the association of tumor growth rate and overall and progression-free survival in metastatic non-small cell lung cancer (NSCLC) patients.

9541 Background: Previous studies have suggested that tumor growth rate (g), estimated using prostate-specific antigen values, is associated with overall survival (OS) in prostate cancer (Wilkerson, 2016). We performed a retrospective pooled analysis in non-small cell lung cancer (NSCLC) to investigate the extent to which g values estimated using radiological tumor measurements in clinical trials are associated with survival. Methods: We identified 24 randomized clinical trials submitted to FDA between 2013 and 2019 investigating either immune checkpoint inhibitor (ICI) or targeted therapy (TT) in pts with metastatic NSCLC. Of 9934 patients (pts) enrolled, 5532 pts (2401, 1189, and 1942 pts treated with ICI, TT, and chemotherapy respectively) had sufficient data to derive a valid g. The g was evaluated by both type and line of therapy. Pts were then grouped according to quartiles of g, with Q1 being the lowest. We calculated OS and progression-free survival (PFS) for each group via the Kaplan-Meier method, and used the Cox model for group comparison. Results: Median g was 9.7E-4, 1.4E-3, and 2.2E-3/day, and median OS was 34.2, 21.3, and 15.3 months (mo), in pts treated with TT, ICI, and chemotherapy, respectively, regardless of lines of therapy. When treated with the same type of therapy, pts receiving 2nd line therapy had a higher median g than those receiving 1st line. The median survival and log-rank hazard ratios for pts treated with 1st line ICI monotherapy are shown in the Table. Conclusions: TT is associated with the lowest median g, followed by ICI, and then chemotherapy, perhaps due to patient selection, better inherent biology/natural history, or favorable results of TT on selected tumors. Regardless, we found that g is inversely associated with survival, across treatment types. This relationship is also observed in pts treated with the same type and line of therapy (for example, 1st line ICI), where Q1 has the longest survival, followed by Q2, Q3, and then Q4. In summary, our exploratory analysis suggests that g derived from radiological tumor measurements in NSCLC may relate to survival. Prospective studies are needed to evaluate if g might be an earlier endpoint compared to classical response criteria. [Table: see text]

Examination of necrosis in tumors treated with AVM0703 compared to chemotherapy.

e20029 Background: AVM0703 should be the first choice for no-option cancer patients. AVM0703 is a fast-acting formulation that lympho-ablates while sparing HSCs, MSCs, platelets, and RBCs. Its transient and manageable side effects reduce the need for additional maintenance treatments while improving quality of life. AVM0703 induces a novel NKT that induces tumor-killing activity without causing GvHD or CRS. AVM0703 is a versatile formulation that can be safely redosed or given in combination with known chemotherapeutics. It is predicted to be safe for previously neglected patient populations. Methods: Mice were monitored over the course of 13 weeks or endpoint criteria. Body weights and tumor measurements were taken 3x per week. Both group and individual growth was tracked. Tumors were dissected from the right flank on takedown and fixed for 24 hours in 4% paraformaldehyde, then stored in 70% ethanol. For analysis, tumors were sent to HistoTox Labs, embedded in paraffin blocks, then sliced and stained for H&E. In a separate study, mice with subcutaneous A20 were treated with increasing concentrations of AVM0703 and allowed to go to endpoint. Tumors were dissected and stained for H&E, CD3, NKp46, and AC3. Finally, tumor bearing mice were treated with high doses of AVM0703 48 hours before takedown. Tumors were dissected and sent to HistoTox for embedding, slicing and staining for H&E, NKp46, CD3, CD49b, AC3, CD31, B220, Ly6G, Sca-1, and PSR. Results: Mice treated with repeat doses of AVM0703 did not display significant loss of body weight or worsening of condition, which was observed in mice treated with chemotherapy. All combination mice displayed significantly higher tumor necrosis and resorption compared to all other treatment groups. Significant necrosis was observed in tumors in as little as 48 hours post dosing. At endpoint, apoptosis was slightly increased at all doses compared to placebo. CD3 and CD49b were decreased in doses above 18 mg/kg, indicating activation of NKT cells in comparison to placebo and low dose AVM0703. There was also an increase in NKp46 staining along the border of large necrotic regions within the tumor. While necrosis was prevalent within the tumor, there was only a slight increase in apoptosis staining. Conclusions: AVM0703 can be repeatedly dosed without significant signs of toxicity. A single dose after 48 hours displays large regions of necrosis within the tumor, indicating that AVM0703 is a fast-acting formulation. AVM0703 is able to replace a dose of Cy/Flu in mice with similar efficacy and increased tumor killing in comparison to Cy/Flu alone with less toxicity.

Co-targeting of CXCR4 and hedgehog pathways disrupts tumor-stromal crosstalk and improves chemotherapeutic efficacy in pancreatic cancer

Pancreatic cancer (PC) remains a therapeutic challenge because of its intrinsic and extrinsic chemoresistance mechanisms. Here, we report that C-X-C motif chemokine receptor 4 (CXCR4) and hedgehog pathways cooperate in PC chemoresistance via bidirectional tumor-stromal crosstalk. We show that when PC cells are co-cultured with pancreatic stellate cells (PSCs) they are significantly more resistant to gemcitabine toxicity than those grown in monoculture. We also demonstrate that this co-culture–induced chemoresistance is abrogated by inhibition of the CXCR4 and hedgehog pathways. Similarly, the co-culture–induced altered expression of genes in PC cells associated with gemcitabine metabolism, antioxidant defense, and cancer stemness is also reversed upon CXCR4 and hedgehog inhibition. We have confirmed the functional impact of these genetic alterations by measuring gemcitabine metabolites, reactive oxygen species production, and sphere formation in vehicle- or gemcitabine-treated monocultures and co-cultured PC cells. Treatment of orthotopic pancreatic tumor–bearing mice with gemcitabine alone or in combination with a CXCR4 antagonist (AMD3100) or hedgehog inhibitor (GDC-0449) displays reduced tumor growth. Notably, we show that the triple combination treatment is the most effective, resulting in nearly complete suppression of tumor growth. Immunohistochemical analysis of Ki67 and cleaved caspase-3 confirm these findings from in vivo imaging and tumor measurements. Our findings provide preclinical and mechanistic evidence that a combination of gemcitabine treatment with targeted inhibition of both the CXCR4 and hedgehog pathways improves outcomes in a PC mouse model.