Proteasomal inhibition revolutionized myeloma therapies in this decade of novel agents. The only US Food and Drug Administration approved proteasome inhibitor so far, bortezomib effectively targets the constitutive proteasome subunit β5 of the 26S proteasome. Bortezomib induces high and quality response rates that are durable. However, myeloma cells acquire resistance to bortezomib through various mechanisms. Further, grade 3/4 peripheral neuropathy is seen in up to a quarter of patients treated with bortezomib. While the recent change in the mode of administration via the subcutaneous route is associated with a lower incidence of grade 3/4 peripheral neuropathy, it remains a major concern. The second generation proteasome inhibitors are promising, with increased preclinical efficacy and a better administration schedule. The current review spotlights the second generation proteasome inhibitors with special focus on the safety and efficacy of carfilzomib, an epoxyketone with lesser peripheral neuropathy, which exhibits irreversible proteasome inhibition. In this article, we review the pharmacology and preclinical and clinical efficacy and safety of carfilzomib alone and in combination with other chemotherapeutic agents in the various lymphoid neoplasms and multiple myeloma as well as ongoing clinical trials.

BACKGROUND One proposed mechanism of extracorporeal photopheresis (ECP) in reducing chronic graft-versus-host disease (cGVHD) is alteration in numbers of circulating dendritic cells (DCs). This hypothesis was tested by correlating numbers of DC precursors and T cells in the blood before and during ECP therapy with response of cGVHD. STUDY DESIGN AND METHODS Twenty-five patients with cGVHD were treated with ECP. Data were collected with emphasis on blood cellular markers, clinical response to ECP, and overall survival. RESULTS Fourteen patients (56%) responded and had better 2-year survival than nonresponders (88% vs. 18%, p = 0.003). Responders had higher baseline circulating myeloid DC (mDC) and plasmacytoid DC precursors and CD4+ and CD8+ T cells compared with nonresponders. Receiver operating characteristic curve analyses showed that the best baseline cutoff values to predict response to ECP were mDC counts of 3.7 cells/µL (79% sensitivity, 82% specificity) and CD4+ T-cell counts of 104 cells/µL (71% sensitivity, 82% specificity). CD4+ T cells declined in responders over time, but not in nonresponders, and no significant changes were seen in CD8 T-cell or DC numbers over a 12-month period in responder or nonresponder groups. CONCLUSIONS Higher baseline numbers of circulating DCs and T cells may predict clinical response to ECP in patients with cGVHD.

Proteasome (PIs) and hystone deacetylase inhibitors (HDACis) have previously shown synergistic activity in the treatment of relapesed/refractory multiple myeloma (RRMM) patients. In this phase 1 study, we combined carfilzomib, a second generation PI, with panobinostat, a HDACi, to determine the maximum tolerated dose (MTD) of the combination (CarPan) and assess safety and efficacy among RRMM patients. Thirty-two patients (median of 4 prior lines of therapy) were enrolled. The MTD was carfilzomib 36 mg/m2 (on days 1, 2, 8, 9, 15, and 16) and panobinostat 20 mg (TIW, 3 weeks on/1 week off, every 28 days), administered until progression. At the MTD, the most common grade 3/4, treatment-related adverse events were thrombocytopenia (41%), fatigue (17%), and nausea/vomiting (12%). The objective response rate (ORR) and clinical benefit rate were 63% and 68%, respectively. Median progression-free survival (PFS) and overall survival (OS) for the entire population were 8 and 23 months, respectively. No differences in terms of ORR (55% vs. 57%), median PFS (months 8 vs. 7 months) and OS (24 vs. 22 months) were observed between bortezomib-sensitive and -refractory patients. CarPan proved to be a safe and effective steroid-sparing regimen in a heavily pre-treated population of MM patients. (Trial registered at ClinicalTrial.gov: NCT01549431)

Introduction The differential diagnosis of neutropenia includes medications, infections, autoimmune diseases, and deficiencies of Vitamin B12 and folate. The association of Vitamin B6 deficiency with severe neutropenia is a rare finding. Case presentation A 51-year-old Caucasian woman presented with fever and profound neutropenia (48 neutrophils/uL). Her clinical history included non-Hodgkin lymphoma, in remission following treatment with allogeneic bone marrow transplantation, quiescent chronic graft-versus-host disease, and squamous cell carcinoma of the skin metastatic to cervical lymph nodes. Medications included atenolol, topical clobetasol, Ditropan (oxybutynin), prophylactic voriconazole, prophylactic valganciclovir, Soriatane (acitretin), and Carac (fluorouracil) cream. The bone marrow was hypocellular without metastatic cancer or myelodysplasia. Neutropenia did not respond to stopping medications that have been associated with neutropenia (valganciclovir, voriconazole and Soriatane) or treatment with antibiotics or granulocyte colony stimulating factor. Blood tests revealed absence of antineutrophil antibodies, normal folate and B12 levels, moderate zinc deficiency and severe Vitamin B6 deficiency. Replacement therapy with oral Vitamin B6 restored blood vitamin levels to the normal range and corrected the neutropenia. Her cervical adenopathy regressed clinically and became negative on scintography following Vitamin B6 therapy and normalization of the blood neutrophil count. Conclusion Severe pyridoxine deficiency can lead to neutropenia. Screening for Vitamin B6 deficiency, along with folate and Vitamin B12 levels, is recommended in patients with refractory neutropenia, especially those with possible malabsorption syndromes, or a history of chronic-graft-versus host disease. Severe neutropenia may facilitate progression of squamous cell carcinoma.