Synergistic Effect of Simultaneous versus Sequential Combined Treatment of Histone Deacetylase Inhibitor Valproic Acid with Etoposide on Melanoma Cells

Targeting the epigenome in malignant melanoma: Facts, challenges and therapeutic promises

Malignant melanoma is the most lethal type of skin cancer with high rates of mortality. Although current treatment options provide a short-clinical benefit, acquired-drug resistance highlights the low 5-year survival rate among patients with advanced stage of the disease. In parallel, the involvement of an aberrant epigenetic landscape, (e.g., alterations in DNA methylation patterns, histone modifications marks and expression of non-coding RNAs), in addition to the genetic background, has been also associated with the onset and progression of melanoma. In this review article, we report on current therapeutic options in melanoma treatment with a focus on distinct epigenetic alterations and how their reversal, by specific drug compounds, can restore a normal phenotype. In particular, we concentrate on how single and/or combinatorial therapeutic approaches have utilized epigenetic drug compounds in being effective against malignant melanoma. Finally, the role of deregulated epigenetic mechanisms in promoting drug resistance to targeted therapies and immune checkpoint inhibitors is presented leading to the development of newly synthesized and/or improved drug compounds capable of targeting the epigenome of malignant melanoma.

Phase II study of sodium valproate in combination with oral etoposide in platinum-resistant ovarian cancer

Patients with platinum-resistant ovarian cancer (PROC) have limited therapeutic options and poor survival. There is a need for the development of newer therapies. Sodium valproic acid (VPA) is a short-chain fatty acid histone deacetylase (HDAC) inhibitor with antitumor activity in preclinical models of PROC. Synergism with conventional cytotoxic agents like etoposide has been demonstrated. In this prospective, single-arm, open-label, phase 2 study, we included patients ≥ 18 years with histologically or cytologically confirmed PROC and Eastern Cooperative Oncology Group performance status (ECOG-PS) 0–3. Patients received oral VPA 60 mg/kg/day in three divided doses for 3 days (D1–D3), followed by oral etoposide 50 mg once daily for two consecutive weeks (D4–D17). Serum samples were collected to assess peak VPA drug levels. The primary endpoint was the overall response rate (ORR). The secondary endpoints were progression-free survival (PFS), overall survival (OS), and toxicity. We sought to show an improvement in response rate from 25% (historically with oral etoposide) to 40% with the addition of VPA. 27 patients were enrolled in the study, and 18 [median age: 52 (45–59) years; serous histology:17 (94%); ECOG-PS 2 or 3: 14 (78%)] were evaluable for the response after 4 months. Nine patients were lost from follow-up before achieving the primary endpoint (mainly due to Covid-related lockdown issues). The median number of prior lines of treatment was 2 (1–3). ORR was 0% according to GCIG criteria. The disease was stable in two patients [clinical benefit rate (CBR) of 11%]. The median OS and PFS were 7 months and 2 months, respectively. Grade ≥ 3 adverse events were reported in 6 (33%) patients. The addition of valproic acid to oral etoposide in patients with PROC and poor general condition was not helpful and failed to improve responses compared to those historically achieved with single-agent etoposide. However, further phase 2 randomized controlled trials with larger sample size can be done to confirm the findings.