No abstract

Objective/Background: Cutaneous immunoglobulin (Ig) amyloid light-chain (AL) amyloidosis associated with overt multiple myeloma (MM) is rare and optimal treatment is not well defined. The recently developed highly efficacious MM therapy has brought on a new set of challenges to this field for consideration. The goal of this paper is to describe the characteristics of cutaneous manifestations of systemic AL amyloidosis associated with MM according to age, sex, race, Ig type, plasma cell percentage, and cytogenetic and fluorescent in situ hybridization studies along with their outcomes. Methods: An electronic search of the PubMed database was performed to obtain key literature in AL amyloidosis and MM, using the following search terms: multiple myeloma, immunoglobulin light chain amyloidosis, and cutaneous amyloidosis. The search results were narrowed by selecting studies in English. Results were confined to the following articles types: case reports, case series, and systematic reviews. Results: We identified 32 cases from the PubMed database search and examined their potential relevance. We found the following: (a) higher prevalence in women (two-thirds) and white population; (b) IgG and IgA were equally distributed with lambda (λ) light chain occurring in 53–66% of cases; (c) majority of cases (56%) presented as hemorrhagic bullous lesions, followed by purpura/ecchymosis in 25% of cases; and (d) majority (64%) died within 6 months since diagnosis. Conclusions: We reviewed the constellation of the cutaneous manifestations of AL amyloidosis with concurrent MM. We found a female predominance, and more than half presented as hemorrhagic bullous lesions. There is a preponderance of λ light chains over kappa (κ) light chains, both as a free light chain (15% vs. 4%) and as an intact Ig (38% vs. 24%; absolute number of 14 vs. 7 patients, respectively). In the subgroup of patients with bullous skin lesions, λ light chain was present in eight cases and κ light chain in seven cases. All κ light chain subtypes presented with bullous lesions and no other cutaneous types of lesions. They carried very poor prognosis with majority of cases surviving only 6 months, much worse than overall patients with AL amyloidosis without myeloma or myeloma without amyloidosis.

The cell surface receptor alpha 4 beta 1 integrin, activated constitutively in lymphoma, can be targeted with the bisaryl urea peptidomimetic antagonist 1 (LLP2A). However, concerns on its preliminary pharmacokinetic (PK) profile provided an impetus to change the pharmacophore from a bisaryl urea to a 2-arylaminobenzimidazole moiety, resulting in improved solubility while maintaining picomolar potency [5 (KLCA4); IC50 = 305 pM]. With exceptional solubility, this finding has the potential for improving PK to help diagnose and treat lymphomas.

Current cancer chemotherapeutic agents clinically deployed today are designed to be indiscriminately cytotoxic, however achieving selective targeting of cancer malignancies would allow for improved diagnostic and chemotherapeutic tools. Integrin α4β1, a heterodimeric cell surface receptor, is believed to have a relaxed conformation in normal cells and an active conformation in cancerous cells, specifically T- and B-cell lymphomas. This highly attractive yet poorly understood receptor has been selectively targeted with the bisaryl urea peptidomimetic antagonist 1. However, concerns regarding its preliminary pharmacokinetic (PK) profile provided an impetus to change the pharmacophore from a bisaryl urea to a 2-arylaminobenzothiazole moiety, resulting in an analog with improved physicochemical properties, solubility and kidney:tumor ratio while maintaining potency (6; IC50 = 53 pM). The results presented herein utilized heterocyclic and solid-phase chemistry, cell adhesion assay, and in vivo optical imaging using the cyanine dye Cy5.5 conjugate.