Neuromuscular Complications of Targeted Anticancer Agents: Can Tyrosine Kinase Inhibitors Induce Myasthenia Gravis? Getting Answers From a Case Report up to a Systematic Review

More than 40 tyrosine kinase inhibitors (TKIs) have received hematological or oncological indications over the past 20 years, following the approval of imatinib, and many others are currently being tested in clinical and preclinical level. Beyond their common toxicities, no certain agent from this large class of molecularly targeted therapies was strongly associated with “off-target” impairment of neuromuscular transmission, and although myasthenia gravis (MG) is a well-characterized autoimmune disorder, only few sporadic events proven by serologically detected causative autoantibodies and/or by positive electrophysiological tests are reported in the literature. Herein, we present the first case of anti-MUSK (+) MG in a woman with metastatic BRAF-mutant melanoma after long-term treatment with dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor). Triggered by this report, a systematic literature review was conducted, summarizing all other cancer cases that developed MG, after exposure to any type of targeted agent and regardless of the underlying malignancy. All available data on the clinical diagnosis, the potential of administered TKIs to induce a seropositive myasthenic syndrome, the immune and non-immune-mediated pathogenesis of postsynaptic damage, and the challenging management of this neuromuscular toxicity were collected and discussed. In the presented case, MG was confirmed by both autoantibodies and nerve-conduction tests, while its reactivation after TKIs rechallenge supports a more than coincidental association. The following review identified 12 cancer cases with TKI-related MG in six case reports and one case series. In most of them, the myasthenia diagnosis was challenging, since the clinical symptomatology of fatigable weakness was not corroborating with consistent laboratory and electrophysiological findings. In fact, anti-AchR titers were positive in five and anti-MuSK only in the abovementioned individual. The symptomatology corresponded to TKI discontinuation and standard treatment with pyridostigmine and prednisolone; intravenous immunoglobulin was added only in three, and two required mechanical ventilation. In an era where TKIs will be prescribed more frequently for various malignancies, even in combinations with immune-checkpoint inhibitors, this report synthesizes their risk for neuromuscular complications and increases the clinicians’ awareness in order to extend the on-treatment and overall survival of TKI-treated cancer patients.

Combining BRAF/MEK Inhibitors with Immunotherapy in the Treatment of Metastatic Melanoma

The management and prognosis of BRAF-mutant metastatic melanoma have changed drastically following the introduction of immune checkpoint inhibitors and molecularly targeted agents. These treatment options present different mechanisms of action and toxicities but also totally distinct kinetics of their response, including a "relatively" short-lasting benefit in subsets of patients treated with BRAF/MEK inhibitors and a lower response rate in patients treated with immune checkpoint inhibitors. BRAF/MEK inhibitors, when administered prior to or concurrently with immune checkpoint inhibitors, at least transiently alter some immunosuppressive parameters of the tumor microenvironment and theoretically improve sensitivity to immunotherapy. Preclinical data from mouse models with oncogene-addicted melanoma confirmed this beneficial immune/targeted synergy and supported the clinical testing of combinations of BRAF/MEK inhibitors and immune checkpoint inhibitors to improve the activity of upfront anti-melanoma therapies. The first positive phase III results were published in 2020, and triggered the discussion about the benefits, the limitations, as well as the possible implications of combining or sequencing targeted therapies with immune checkpoint inhibitors in everyday practice. Beginning from the interplay of immune/targeted agents within the melanoma microenvironment, this review outlines available information from the retrospective experience up to the late-stage randomized evidence on combinatorial treatments. Many clinical trials are currently underway exploring open questions about optimal timing, new immune biomarkers, and eligible patient subsets for these immune/targeted regimens. Awaiting these results, decision making in the first-line setting for BRAF-mutant melanoma is still guided by the patients' characteristics and the biological aspects of melanoma.

Identifying the optimum first-line therapy in BRAF-mutant metastatic melanoma

Introduction: The emergence of molecularly targeted agents and immune checkpoint inhibitors has positively revolutionized the management and prognosis of BRAF-mutant metastatic melanoma. However, the availability of both therapeutic options, with their pros and cons, rationally triggered clinical considerations for the optimum frontline and subsequent treatment decisions.Areas covered: Here, we debate all approved therapies in patients with BRAF-mutant metastatic melanoma evaluating their efficacy and safety based on their pivotal trials. With prospective randomized data pending, retrospective comparisons of BRAF/MEK versus immune checkpoint inhibitors are reviewed to recognize any advantage between these two alternatives and to optimize their implementation. Preclinical and early clinical results of combining concurrently or sequentially targeted therapy and immunotherapy are also discussed.Expert opinion: BRAF/MEK inhibitors produce rapid and deep responses and should be included in first-line approaches, particularly in cases with aggressive and bulky disease, while single or double checkpoint inhibition lead to more durable responses and could be involved either in frontline treatment of BRAF-mutant melanoma with less unfavorable characteristics or in maintenance after initial targeted induction or in future immune/targeted regimens for high-risk groups. Data from ongoing trials directly comparing or combining these strategies are expected to update their role in a more individualized basis.

Significance of survivin mRNA blood levels in patients with melanoma

PURPOSE

Survivin represents a key anti-apoptotic molecule that is highly expressed in the vast majority of tumors. The aim of the study was to examine the significance of survivin mRNA blood levels in melanoma patients.

METHODS

In this prospective translational research study, survivin mRNA blood levels were measured in melanoma patients treated with adjuvant interferon or systemic treatment for advanced disease.

RESULTS

Sixty-four patients with melanoma and 40 healthy controls were included. The majority of them had tumor stages III and IV. The upper 95% confidence interval (95%CI) of survivin levels in controls was set as normal cut-off. Fifty-two (81.3%) patients had survivin levels above normal cut-off. Melanoma patients had higher survivin levels than controls (p<0.0001). Survivin levels were non-significantly higher in stage III compared to stage IV patients. Patients with survivin levels above vs. below median had median progression-free survival (PFS) 19.5 months vs. 7.4 months (p=0.045), but median overall survival (OS) not reached vs. 18.4 months (p=0.091). Cox proportional hazard models showed that only tumor stage was associated with PFS and OS. There was no statistically significant change in survivin levels between baseline and during treatment (p=0.845) or during follow-up (p=0.101).

CONCLUSION

Although melanoma patients had significantly higher survivin levels than controls, the study showed that survivin mRNA blood levels did not represent an independent prognostic factor for patients with melanoma. The role of circulating survivin should be further examined in larger studies.