News in brief: 3 haematology drugs among most expensive for PBS; Antihistamines enhance response to cancer immunotherapy; Funding plea for bone marrow donor registry

Thursday, 2 Dec 2021

3 haematology drugs among most expensive for PBS

Three drugs with haematology indications are on the Top 10 PBS drugs list by cost to government released by NPS MedicineWise this week.

Lenalidomide (Revlimid), which is listed on the PBS for treatment of multiple myeloma, was ranked ninth most expensive, at a cost of $221,365,364 for the year July 2020 – June 2021, based on 40,554 prescriptions.

The DOAC anticoagulant apixaban (Eliquis) was the sixth most expensive drug for the PBS with a cost of $248,455,067 for 3,020,507 prescriptions.

Pembrolizumab (Keytruda) which is PBS listed for the treatment of elapsed/refractory classical Hodgkin Lymphoma and some other lymphomas had a cost of $431,701 ,955 for 49,694 prescriptions. However pembrolizumide is also PBS listed for several solid cancers.

The most costly PBS listed drugs to government were aflibercept for age related macular degeneration (AMD) with a cost of $443,729,600 per year and cancer drug nivolumab (Opdivo), which cost $402, 1 1 3 ,073 last year.

Antihistamines may enhance response to cancer immunotherapy

Cancer patients on immunotherapy could see added efficacy and survival benefits with concurrent H1-antihistamines, a new study suggests.

The study of 2,864 cancer patients on immuno- or chemotherapy with or without antihistamines found that anti-PD-1/PD-L1-treated lung cancer and melanoma patients on antihistamines had significantly improved survival over those off antihistamines (P = 0.015 and 0.0065 respectively).

Breast cancer and colon cancer patients on immunotherapy also saw a survival benefit, though not statistically significant due to the relatively small number of antihistamine-users.

“Notably, H1-antihistamines had minimal effect on the survival of chemotherapy-treated patients, suggesting that H1-antihistamines may not target tumor cells directly,” the authors wrote in Cancer Cell.

Instead, the drugs likely affect macrophages, which can become dysfunctional when exposed to high levels of histamine and histamine receptor H1 (HRH1) in the tumour microenvironment.

“Mechanistically, HRH1-activated macrophages polarise toward an M2-like immunosuppressive phenotype with increased expression of the immune checkpoint VISTA, rendering T cells dysfunctional,” the authors wrote.

“Antihistamine treatment reverted macrophage immunosuppression, revitalised T cell cytotoxic function, and restored immunotherapy response”.

They noted that histamine-HRH1-related allergy “facilitated tumour growth and induced immunotherapy resistance in mice and humans” and that “cancer patients with low plasma histamine levels had a more than tripled objective response rate to anti-PD-1 treatment compared with patients with high plasma antihistamine”.

“Altogether, pre-existing allergy or high histamine levels in cancer patients can dampen immunotherapy responses and warrant prospectively exploring antihistamines as adjuvant agents for combinatorial immunotherapy,” they concluded.

Funding plea for bone marrow donor registry

The Australian Bone Marrow Donor Registry must fund new recruitment campaigns because more than 80% of recipients of unrelated-donor transplants now receive their transplants from international donors, advocates say.

Reliance on overseas donor registries creates inequities for local allogeneic bone marrow transplant patients because HLA variations mean that Australians from ethnic and Indigenous backgrounds are less likely to find a donor, according to an article by haematologists Dr Eddie Cliff and Professor Jeff Szer.

International donors are also more difficult to access during the COVID-19 era, which has led to a higher proportion of patients relying on the ABMDR and a lower proportion of young male donors, they write in Internal Medicine Journal.

They call for reinstatement of the successful Strength to Give recruitment campaign that was halted in May 2021 due to a lack of ongoing funding.

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