TPX-0131, a Potent CNS-penetrant, Next-generation Inhibitor of Wild-type ALK and ALK-resistant Mutations

Since 2011, with the approval of crizotinib and subsequent approval of four additional targeted therapies, anaplastic lymphoma kinase (ALK) inhibitors have become important treatments for a subset of patients with lung cancer. Each generation of ALK inhibitor showed improvements in terms of central nervous system (CNS) penetration and potency against wild-type (WT) ALK, yet a key continued limitation is their susceptibility to resistance from ALK active-site mutations. The solvent front mutation (G1202R) and gatekeeper mutation (L1196M) are major resistance mechanisms to the first two generations of inhibitors while patients treated with the third-generation ALK inhibitor lorlatinib often experience progressive disease with multiple mutations on the same allele (mutations in cis, compound mutations). TPX-0131 is a compact macrocyclic molecule designed to fit within the ATP-binding boundary to inhibit ALK fusion proteins. In cellular assays, TPX-0131 was more potent than all five approved ALK inhibitors against WT ALK and many types of ALK resistance mutations, e.g., G1202R, L1196M, and compound mutations. In biochemical assays, TPX-0131 potently inhibited (IC50 <10 nmol/L) WT ALK and 26 ALK mutants (single and compound mutations). TPX-0131, but not lorlatinib, caused complete tumor regression in ALK (G1202R) and ALK compound mutation-dependent xenograft models. Following repeat oral administration of TPX-0131 to rats, brain levels of TPX-0131 were approximately 66% of those observed in plasma. Taken together, preclinical studies show that TPX-0131 is a CNS-penetrant, next-generation ALK inhibitor that has potency against WT ALK and a spectrum of acquired resistance mutations, especially the G1202R solvent front mutation and compound mutations, for which there are currently no effective therapies.

Abstract 1469: TPX-0131, a potent inhibitor of wild type ALK and a broad spectrum of both single and compound ALK resistance mutations

Three generations of ALK inhibitors are approved for the treatment of ALK+ NSCLC but their efficacy is often limited by ALK resistance mutations. The solvent front mutation G1202R and gatekeeper mutation L1196M are major resistance mechanisms to the first two generations of inhibitors. Patients treated with second generation inhibitors are reported to progress with multiple mutations on separate alleles (mutations in trans). In contrast, 35 - 48% of patients treated with lorlatinib progress with multiple mutations on the same allele (compound mutations, mutations in cis). TPX-0131 is an ALK inhibitor with a compact macrocyclic structure designed to bind completely within the ATP binding boundary and overcome a spectrum of single and compound ALK resistant mutations. TPX-0131 was profiled against previous generations of ALK inhibitors both in vitro and in vivo. In biochemical assays, TPX-0131 potently inhibits (IC50 &lt;10 nM) wild type (WT) ALK and 26 ALK mutations (single and compound). Cell proliferation assays of WT, single mutations, and compound mutations were used to evaluate TPX-0131 relative to previous generations of ALK inhibitions (crizotinib, alectinib, brigatinib, ceritinib, lorlatinib). TPX-0131 is more potent against WT EML4-ALK (IC50 = 0.4 nM) than previous generations of ALK inhibitors (2-fold, lorlatinib; 10 - 30-fold, second generation inhibitors; &gt;100-fold, crizotinib). TPX-0131 potently inhibits EML4-ALK harboring a G1202R solvent front mutation (IC50 = 0.2 nM) which is &gt;100-fold more potent than previous generations of ALK inhibitors. TPX-0131 potently inhibits ALK harboring a gatekeeper mutation (IC50 = 0.5 nM) and is &gt;10-fold more potent than previous generations of ALK inhibitors. TPX-0131 potently inhibits ALK with a L1198F hinge area mutation (IC50 = 0.2 nM) which is 87 - 3000-fold more potent than previous generations of ALK inhibitors. TPX-0131 is the most potent inhibitor against nine EML4-ALK double and triple compound mutations (6 with IC50 &lt; 1 nM, 3 with IC50 1.6 - 14.9 nM). Evaluation of ALK phosphorylation as a pharmacodynamic marker in tumors showed potent ALK inhibition by TPX-0131 that correlated with TPX-0131 exposure. In Ba/F3 cell-derived xenograft tumor models with EML4-ALK mutations, TPX-0131 (2, 5, 10 mg/kg BID) demonstrated robust anti-tumor activity in the G1202R model (64%, 120%, 200% TGI), G1202R/L1198F model (complete regression, all doses), and G1202R/L1196M model (44%, 83% and 200% TGI). In contrast, lorlatinib (5 mg/kg BID) caused 31% TGI in the G1202R/L1198F model and did not have statistically significant TGI in the G1202R/L1196M model. Taken together, TPX-0131 is a next generation ALK inhibitor that has preclinical potency against WT ALK as well as a broad spectrum of acquired resistance mutations, especially compound mutations, which currently lack any effective ALK inhibitor therapy.

Citation Format: Brion W. Murray, Dayong Zhai, Wei Deng, Evan Rogers, Xin Zhang, Jane Ung, Vivian Nguyen, Han Zhang, Maria Barrera, Ana Parra, Jessica Cowell, Dong Lee, Herve Aloysius. TPX-0131, a potent inhibitor of wild type ALK and a broad spectrum of both single and compound ALK resistance mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1469.

Design, synthesis, and evaluation of l-cystine diamides as l-cystine crystallization inhibitors for cystinuria

To overcome the chemical and metabolic stability issues of l-cystine dimethyl ester (CDME) and l-cystine methyl ester (CME), a series of l-cystine diamides with or without Nα-methylation was designed, synthesized, and evaluated for their inhibitory activity of l-cystine crystallization. l-Cystine diamides 2a-i without Nα-methylation were found to be potent inhibitors of l-cystine crystallization while Nα-methylation of l-cystine diamides resulted in derivatives 3b-i devoid of any inhibitory activity of l-cystine crystallization. Computational modeling indicates that Nα-methylation leads to significant decrease in binding of the l-cystine diamides to l-cystine crystal surface. Among the l-cystine diamides 2a-i, l-cystine bismorpholide (CDMOR, LH707, 2g) and l-cystine bis(N'-methylpiperazide) (CDNMP, LH708, 2h) are the most potent inhibitors of l-cystine crystallization.

l-Cystine Diamides as l-Cystine Crystallization Inhibitors for Cystinuria

l-Cystine bismorpholide (1a) and l-cystine bis(N'-methylpiperazide) (1b) were seven and twenty-four times more effective than l-cystine dimethyl ester (CDME) in increasing the metastable supersaturation range of l-cystine, respectively, effectively inhibiting l-cystine crystallization. This behavior can be attributed to inhibition of crystal growth at microscopic length scale, as revealed by atomic force microscopy. Both 1a and 1b are more stable than CDME, and 1b was effective in vivo in a knockout mouse model of cystinuria.

Targeted prodrug approaches for hormone refractory prostate cancer

Due to the propensity of relapse and resistance with prolonged androgen deprivation therapy (ADT), there is a growing interest in developing non-hormonal therapeutic approaches as alternative treatment modalities for hormone refractory prostate cancer (HRPC). Although the standard treatment for HRPC consists of a combination of ADT with taxanes and anthracyclines, the clinical use of chemotherapeutics is limited by systemic toxicity stemming from nondiscriminatory drug exposure to normal tissues. In order to improve the tumor selectivity of chemotherapeutics, various targeted prodrug approaches have been explored. Antibody-directed enzyme prodrug therapy (ADEPT) and gene-directed enzyme prodrug therapy (GDEPT) strategies leverage tumor-specific antigens and transcription factors for the specific delivery of cytotoxic anticancer agents using various prodrug-activating enzymes. In prostate cancer, overexpression of tumor-specific proteases such as prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) is being exploited for selective activation of anticancer prodrugs designed to be activated through proteolysis by these prostate cancer-specific enzymes. PSMA- and PSA-activated prodrugs typically comprise an engineered high-specificity protease peptide substrate coupled to a potent cytotoxic agent via a linker for rapid release of cytotoxic species in the vicinity of prostate cancer cells following proteolytic cleavage. Over the past two decades, various such prodrugs have been developed and they were effective at inhibiting prostate tumor growth in rodent models; several of these prodrug approaches have been advanced to clinical trials and may be developed into effective therapies for HRPC.

A novel high-yield synthesis of aminoacyl p-nitroanilines and aminoacyl 7-amino-4-methylcoumarins: Important synthons for the synthesis of chromogenic/fluorogenic protease substrates

Aminoacyl p-nitroaniline (aminoacyl-pNA) and aminoacyl 7-amino-4-methylcoumarin (aminoacyl-AMC) are important synthons for the synthesis of chromogenic/fluorogenic protease substrates. A new efficient method was developed to synthesize aminoacyl-pNA and aminoacyl-AMC derivatives in excellent yields starting from either amino acids or their corresponding commercially available N-hydroxysuccinimide esters. The method involved the in situ formation of selenocarboxylate intermediate of protected amino acids and the subsequent non-nucleophilic amidation with an azide. Common protecting groups used in amino acid/peptide chemistry were all well-tolerated. The method was also successfully applied to the synthesis of a dipeptide conjugate, indicating that the methodology is applicable to the synthesis of chromogenic substrates containing short peptides. The method has general applicability to the synthesis of chromogenic and fluorogenic peptide substrates and represents a convenient and high-yield synthesis of N^α-protected-aminoacyl-pNAs/AMCs, providing easy access to these important synthons for the construction of chromogenic/fluorogenic protease substrates through fragment condensation or stepwise elongation.