Using multimodal single-cell sequencing and ex vivo functional assays, we demonstrate that DRP-104 reverses T cell exhaustion, decreases Tregs, and enhances the function of CD4 and CD8 T cells, culminating in an improved response to anti-PD1 therapy. Our preclinical findings provide compelling evidence that DRP-104, currently in clinical trials, offers a promising therapeutic approach for treating patients with KEAP1 mutant lung cancer.

The glutamine antagonist DRP-104 blocks purine synthesis and combines with checkpoint inhibitors to promote antitumor immunity in KEAP1/NRF2-mutant lung cancers.

Thyroid cancer exhibited enhanced glutamine metabolism, as evidenced by the glutamine dependence of thyroid cancer cells and high expression of multiple glutamine metabolism-related genes. Targeting glutamine metabolism with DON prodrug could be a promising therapeutic option for advanced thyroid cancer.

P1/2, N=27, Recruiting, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins | Phase classification: P1b/2 --> P1/2

P1/2, N=27, Recruiting, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins | Not yet recruiting --> Recruiting

P1/2, N=27, Not yet recruiting, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins

Preclinical work from our laboratory and others has revealed that the DNAJB1-PRKACA fusion results in a metabolic rewiring of the tumor characterized by glutamine dependence. This study has been registered under NCT06027086 and is expected to begin enrollment in December 2023. Clinical trial information: NCT06027086.

This effect is specific to TERT-expressing GBM cells because the combination of DON and BSO does not affect viability of normal astrocytes or astrocytomas that use the ALT pathway for telomere maintenance. Importantly, in vivo stable isotope tracing confirmed that combined treatment with JHU-083 (a brain-penetrant prodrug of DON) and BSO abrogates synthesis of GSH, aspartate, and pyrimidine nucleotides from [U-13C]-glutamine and induces apoptotic death in mice bearing intracranial GBM6 tumors.Collectively, our studies highlight the therapeutic potential of targeting metabolic vulnerabilities induced by TERT expression in GBMs in vivo.

Based on prior studies showing enhanced efficacy when GA inhibition was combined with the antimetabolite 6-mercaptopurine (6-MP), we hypothesized that such a combination would be efficacious in MPNST. When combined with JHU395, Pro-905 enhanced the colony formation inhibitory potency of JHU395 in human MPNST cells and augmented the antitumor efficacy of JHU395 in mice. In summary, the dual inhibition of the de novo and purine salvage pathways in preclinical models may safely be used to enhance therapeutic efficacy against MPNST.

P2a, N=61, Terminated, Dracen Pharmaceuticals, Inc. | N=246 --> 61 | Trial completion date: Dec 2023 --> Mar 2023 | Active, not recruiting --> Terminated; Company decision to closing study and discontinue further patient enrollment.

Moreover, JHU-083, a specific pharmacologic inhibitor of glutaminase, killed ZFTA-RELAFUS tumor cells in vitro and in vivo. To summarize, our results suggest that the ZFTA-RELA fusion expressing tumor cells exhibit strong glutamine dependence, and targeting it has significant therapeutic relevance.

Overall, we find that DRP-104 impairs the growth of KEAP1 mutant tumors through both targeting of tumor intrinsic metabolic vulnerabilities and through tumor extrinsic immunostimulatory mechanisms such as promoting the expansion of functional anti-tumor T cell populations. This data provides additional rationale for the ongoing phase I/II clinical trial (NCT04471415) using DRP-104 in NSCLC with mutations in KEAP1 as well as for combining DRP-104 with checkpoint blockade.

P2a, N=246, Active, not recruiting, Dracen Pharmaceuticals, Inc. | Recruiting --> Active, not recruiting

Infusions with [amide-N]glutamine revealed persistent amidotransferase activity during glutaminase inhibition, and blocking these activities with the amidotransferase inhibitor JHU-083 also reduced tumor growth in both immunocompromised and immunocompetent mice. We conclude that ccRCC tumorgrafts catabolize glutamine via multiple pathways, perhaps explaining why it has been challenging to achieve therapeutic responses in patients by inhibiting glutaminase.

In addition, we found that the glutamine metabolism inhibitor JHU083 promoted the proliferation of CD8T cells and improved the efficacy of PD-1 blockers. We proposed a new tool to quantify the glutamine partitioning between tumor cells and CD8T cells, through which the unique immune microenvironment could be identified at the transcriptome level. Furthermore, the simultaneous destruction of the glutamine metabolism in tumor cells and CD8T cells facilitated the enrichment of tumor-infiltrating CD8T cells and enhanced the efficacy of immunotherapy.

In addition, NDRG2 more significantly inhibited the protein level of PC in isocitrate dehydrogenase 1 (R132H)-mutant glioma cells than in wild-type glioma cells. These findings indicate that the molecular mechanism of NDRG2 inhibits PC-mediated anaplerosis and collaborates with glutamine antagonist to inhibit the malignant proliferation of glioma cells, thus providing a theoretical and experimental basis for targeting anaplerosis in glioma therapy.

Interestingly, Th1 cells are found to robustly upregulate oxidative metabolism and adopt a highly activated and memory-like phenotype upon glutamine inhibition. These results suggest that JHU083 is highly effective against EGFR-driven lung tumorigenesis and promotes an adaptive T cell-mediated tumor-specific immune response that enhances the efficacy of EVax.

However, the administration L-ASP catalyzed glutamine depletion with irradiated co-cultures and catalyzed tumor volume reduction in a mouse model. The clinical history of L-ASP for leukemia patients supports the viability for its repurposing as a radio-sensitizer for PCa patients.

Our data suggest that broad glutamine antagonism using sirpiglenastat (DRP-104) has therapeutic potential in HNSCC by dismantling cancer metabolism and sensitizing cells to additional perturbations leading to specific cell death. A clinical trial of sirpiglenastat (DRP-104) is currently ongoing (NCT04471415).

Our studies will provide a rationale for sub-stratification of KEAP1-mutant patients with hyperactivation of the NRF2 pathway, which is a genetic subset of NSCLC with great clinical need, as treatment candidates for sirpiglenastat. A first-in-human clinical trial of sirpiglenastat (DRP-104) is currently ongoing and will further explore this hypothesis in a LUAD cohort (NCT04471415).

Treatment of mice bearing orthotopic xenografts of human MYC-amplified medulloblastoma with JHU395 increased median survival from 26 to 45 days compared with vehicle control mice (p < 0.001 by log-rank test). These data provide preclinical justification for the ongoing development and testing of brain-targeted DON prodrugs for use in medulloblastoma.

Long term administration of JHU-083 did not decrease bodyweight in mice. Together with previous results, these data suggest that JHU083 could be used to reshape the tumor microenvironment toward one that enhances antitumor T cell responses and could further enhance the efficacy of the EGFR anticancer vaccine.

However, less than 20% of HNSCC patients respond to FDA-approved anti-PD1 immune checkpoint blockade (ICB) (pembrolizumab and nivolumab), often not leading to durable responses. Our data suggest that broad glutamine antagonism using DRP-104 has therapeutic potential in HNSCC by both dismantling cancer metabolism and enhancing the anti-tumor immune response of immune checkpoint blockade. Clinical trials of DRP-104 are currently ongoing.

Twice weekly 15mg/kg dosing of JHU395 significantly extended the survival of the mice with D425 MED orthotopic xenografts (p<0.001 by log-rank test comparing treated vs vehicle control). Glutamine antagonists exploit MYC-amplified medulloblastoma's reliance on glutamine metabolism and may have therapeutic applications in human patients.

Importantly, this metabolic signature is predictive of either response or resistance to targeted therapies that inhibit glucose and glutamine metabolism that may be exploited in a clinical setting.We previously reported that combined targeting of glucose and glutamine metabolism with mTOR kinase inhibitor TAK228 or TKI in combination with the selective glutaminase (GLS) inhibitor CB-839 was required to significantly suppress glucose and glutamine metabolism in both LUSC and EGFR mutant LUADs resulting in metabolic crisis and tumor cell death3,5. Overall, DRP-104 showed great potential to treat hypermetabolic therapy-resistant LUSC and EGFR mutant LUAD as a single-agent therapy and in combination with immune CPI. Further clinical development of DRP-104 in this patient population is warranted and clinical trials are currently ongoing.

This unique and non-overlapping mechanism of action supports clinical development of DRP-104 alone and in combination with immune checkpoint inhibitors. The first in human clinical study of DRP-104 is ongoing.

Tumor metabolomics studies were performed to investigate metabolic differences between single agent JHU395, Pro-905, and combination treated mice. Protide purine antimetabolites in combination with glutamine antagonists are tolerated and efficacious in Ras-driven sarcoma models in preclinical studies.

Finally, JHU-083 extended survival in an intracranial IDH1 mut glioma model and reduced intracranial pS6 protein expression. Targeting glutamine metabolism with JHU-083 showed efficacy in preclinical models of IDHmut glioma and measurably decreased mTOR signaling.

P2a, N=246, Recruiting, Dracen Pharmaceuticals, Inc. | N=160 --> 246 | Trial completion date: Jul 2023 --> Dec 2023

P2a, N=160, Recruiting, Dracen Pharmaceuticals, Inc. | Not yet recruiting --> Recruiting

P2a, N=160, Not yet recruiting, Dracen Pharmaceuticals, Inc.

Combination therapy of DRP-104 with anti-PD-1/PD-L1 achieved significantly enhanced anti-tumor efficacy including long-term durable cures even in checkpoint inhibitor resistant models. This unique and non-overlapping mechanism of action supports clinical development of DRP-104 alone and in combination with PD-1/PD-L-1 checkpoint inhibitors.