Cost-effectiveness of a 12-month fixed duration of Venetoclax in combination with Obinutuzumab versus chemoimmunotherapy and other novel combinations in first-line chronic lymphocytic leukemia in Canada

Objectives

To estimate the cost-effectiveness of venetoclax + obinutuzumab (GAZYVA®, G), (VEN+G) in the treatment of first-line (1L) chronic lymphocytic leukemia (CLL) from a Canadian health care system cost perspective.

Methods

A three-state partitioned-survival model was used to extrapolate progression-free survival (PFS) and overall survival (OS) over a 10-year time horizon. Cost-effectiveness was estimated comparing 12-month fixed duration of VEN+G versus (vs) G + Chlorambucil (GClb) based on the CLL14 clinical trial (NCT02242942). Other comparators included Bendamustine + rituximab (BR), Chlorambucil + rituximab (Clb+R), Ibrutinib (Ibr), Acalabrutinib (Acala) and Acalabrutinib + GAZYVA (Acala+G). VEN+G was also compared to the combination of fludarabine, cyclophosphamide and rituximab (FCR) in the overall 1L CLL population which included unfit and fit patients. Relative efficacy of VEN+G vs other comparators was estimated using a network meta-analysis. Health state utilities and adverse event disutilities were derived from a systematic literature review and other published sources. Costs included CLL treatment, routine care and monitoring, adverse events, disease progression costs, subsequent treatment costs, and end of life care. Uncertainty was assessed using an underlying probabilistic model (probabilistic analysis of uncertainty generated from 5,000 iterations), through deterministic sensitivity analyses (i.e., one-way sensitivity analyses (OWSA)), and through a series of alternative scenario analyses.

Results

For the overall unfit 1L CLL patient population, the probabilistic total discounted costs incurred over a 10-year time horizon were as follows: $217,727 for VEN+G vs $312,287 for GClb, $399,219 for BR, $380,713 for Clb+R, $736,017 for Ibr, $868,797 for Acala and $916,139 for Acala+G. The probabilistic total discounted quality adjusted life years (QALYs) were 4.964 for VEN+G vs 4.750, 4.550, 4.422, 4.709, 5.269, and 5.359, respectively for the comparators.

For the overall 1L CLL patient population, the probabilistic total discounted costs were $219,651 for VEN+G vs $312,570 for GClb, $342,195 for FCR, $397,262 for BR, $380,551 for Clb+R, $757,129 for Ibr, $868,388 for Acala, and $916,798 for Acala+G. The probabilistic total discounted QALYs were 5.888 for VEN+G vs 5.519, 5.067, 5.198, 5.073, 5.597, 6.259 and 6.380, respectively for the comparators.

VEN+G was found to be less costly and more efficacious (i.e., dominant) compared to GClb, BR, Clb+R, Ibr and FCR. As a result, incremental cost utility ratios (ICERs) were not calculated for these comparators. Acala and Acala+G resulted in ICERs ranging from $1.4-$2.1 million per QALY gained relative to VEN+G, which is not cost-effective. Based on the probabilistic model and 5,000 simulations, VEN+G was found to be at least 97% cost-effective across all decision maker willingness-to-pay thresholds.

The results from the deterministic model were found to be similar to the probabilistic model. Using the deterministic model, and in comparison to the most commonly prescribed treatment for 1L CLL in Canada (i.e., Ibr), the OWSA comparing VEN+G to Ibr found that the most influential variables in the model were the PFS and OS hazard ratios for Ibr and the utility values for PFS and post-progression survival.

Conclusions 

VEN+G is an effective novel fixed duration treatment option which leads to deep and durable responses for the treatment of patients with unfit 1L CLL and provides excellent value-for-money compared with existing chemoimmunotherapy and treat to progression novel combinations.