Lys05

Lys05, or Lys01 trihydrochloride, is a potent, water soluble lysosomal autophagy inhibitor. Lys05 is a previously undescribed dimeric chloroquine which more potently accumulates in the lysosome and blocks autophagy compared with HCQ. Lys05 produced more potent antitumor activity as a single agent both in vitro and in vivo in multiple human cancer cell lines and xenograft models compared with HCQ. Lys05 is therefore a new lysosomal autophagy inhibitor that has potential to be developed further into a drug for cancer and other medical applications.

Lys05 (Lys01 trihydrochloride) is a dimeric chloroquine (CQ) that deacidifies the lysosome and causes impairment of lysosomal enzymes, exhibiting more than 10-fold higher autophagy inhibitory potency than hydroxychloroquine (HCQ) and CQ (LC3II/LC3I ratio = 15.4 post 4 hr 10 μM treatment in LN229 glioblastoma cells vs. <6.4 with 100 μM CQ or HCQ). Lys05 also shows higher anticancer activity both in vitro (IC50 3.6-6.0 μM vs. 15.6-23.8 μM with HCQ in 1205Lu, c8161, LN229, HT-29 cultures) and in mice in vivo (EC50 in reducing tumor growth rate ～10 mg/kg/day i.p.; HT29 xenografts) with toxicity observed only at high doses (≥80 mg/kg) as a result of significant lysozyme reduction.

In two melanoma xenograft models and a colon cancer xenograft model, intermittent high dose Lys05 or chronic daily dosing of Lys05 at lower doses produces significant early blockade of autophagy in vivo, and has single-agent antitumor activity at doses as low as 10 mg/kg i.p. daily. In contrast, single-agent high dose HCQ treatment administered intermittently does not produce clear evidence of autophagy inhibition at early time points, and is associated with tumor growth compared with control in one model. To better understand these findings, the lysosomal drug accumulation and functional deacidification of lysosomes in Lys05 and HCQ treated cells was compared. Compared with HCQ, Lys05 more potently accumulates within and deacidifies the lysosome of both cells and tumors, resulting in more sustained inhibition of autophagy and tumor growth. While even 100 μM HCQ cannot completely deacidify the endovesicular compartment in cancer cells, complete deacidification is observed with 50 μM Lys05 as evidenced by acridine orange aggregation. _x000D_ _x000D_ Reference: Autophagy. 2012 Sep 1; 8(9): 1383–1384. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3442884/

Lys05 (Lys01 trihydrochloride) is a lysosomal autophagy inhibitor with IC50 values of 3.6, 3.8, 6 and 7.9 μM for 1205Lu, c8161, LN229 and HT-29 cell line in the MTT assay.